1
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Lim JH, Kim DH, Noh KH, Jung CR, Kang HM. The proliferative and multipotent epidermal progenitor cells for human skin reconstruction in vitro and in vivo. Cell Prolif 2022; 55:e13284. [PMID: 35723171 PMCID: PMC9436902 DOI: 10.1111/cpr.13284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/16/2022] [Accepted: 05/23/2022] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES The skin exhibits tremendous regenerative potential, as different types of progenitor and stem cells regulate skin homeostasis and damage. However, in vitro primary keratinocytes present with several drawbacks, such as high donor variability, short lifespan, and limited donor tissue availability. Therefore, more stable primary keratinocytes are needed to generate multiple uniform in vitro and in vivo skin models. RESULTS We identified epidermal progenitor cells from primary keratinocytes using Integrin beta 1 (ITGB1) an epidermal stem cell marker markedly decreased after senescence in vitro. Epidermal progenitor cells exhibited unlimited proliferation and the potential for multipotent differentiation capacity. Moreover, they could completely differentiate to form an organotypic skin model including conversed mesenchymal cells in the dermis and could mimic the morphologic and biochemical processes of human epidermis. We also discovered that proliferation and the multipotent differentiation capacity of these cells relied on ITGB1 expression. Eventually, we examined the in vitro and in vivo wound healing capacity of these epidermal progenitor cells. CONCLUSIONS Overall, the findings suggest that these stable and reproducible cells can differentiate into multiple lineages, including human skin models. They are a potentially powerful tool for studying skin regeneration, skin diseases, and are an alternative for in vivo experiments.
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Affiliation(s)
- Jung Hwa Lim
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Dae Hun Kim
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Kyung Hee Noh
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Cho-Rok Jung
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Hyun Mi Kang
- Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
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2
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Keratin expression in gingival tissue and primary cultured gingival keratinocytes: Are there differences? Arch Oral Biol 2020; 117:104780. [PMID: 32535293 DOI: 10.1016/j.archoralbio.2020.104780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 05/19/2020] [Accepted: 05/24/2020] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate whether the process of primary gingival keratinocytes culture obtained from normal human gingiva modifies the expression of keratins (K) 10, K14, and K19. DESIGN Human gingival fragments were collected from healthy individuals in the same oral site. One part of the samples underwent an immunohistochemistry assay for K10, K14, and K19. The labeling in the epithelium was quantified using a semiautomated method. Another part was used for primary gingival keratinocytes isolation and growth in two-dimensional culture. These cells were also stained for K10, K14, and K19 using immunofluorescence and immunocytochemistry. Positive cells were counted, and the nuclei and cytoplasmatic labeling areas were quantified. RESULTS In the gingival tissue, a higher expression was found for K14 versus K10 (p < 0.001); K19 was negative in all samples. In gingival keratinocytes culture, K14 (89.6 %) had the highest expression with significant differences in relation to K10 (76.9 %, p < 0.01) and K19 (9.9 %, p < 0.01). The cells positive for K14 exhibited larger nuclei in comparison with K10 (p < 0.05) and K19 (p < 0.05), suggesting a more undifferentiated phenotype. K19 cells showed the largest cytoplasmatic labeling in relation to K10- (p < 0.05) and K14-positive (p < 0.05) cells. CONCLUSION The process of growth in culture of gingival keratinocytes maintained the expression pattern of K10 and K14 observed in gingival tissues. However, this method induces the expression of K19, suggesting a potential transformation of the keratin network presented in the gingival keratinocytes during the formation of a monolayer in vitro. This reflects the dynamics of cell differentiation.
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3
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Chen W, Alshaikh A, Kim S, Kim J, Chun C, Mehrazarin S, Lee J, Lux R, Kim RH, Shin KH, Park NH, Walentin K, Schmidt-Ott KM, Kang MK. Porphyromonas gingivalis Impairs Oral Epithelial Barrier through Targeting GRHL2. J Dent Res 2019; 98:1150-1158. [PMID: 31340691 DOI: 10.1177/0022034519865184] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Oral mucosa provides the first line of defense against a diverse array of environmental and microbial irritants by forming the barrier of epithelial cells interconnected by multiprotein tight junctions (TJ), adherens junctions, desmosomes, and gap junction complexes. Grainyhead-like 2 (GRHL2), an epithelial-specific transcription factor, may play a role in the formation of the mucosal epithelial barrier, as it regulates the expression of the junction proteins. The current study investigated the role of GRHL2 in the Porphyromonas gingivalis (Pg)-induced impairment of epithelial barrier functions. Exposure of human oral keratinocytes (HOK-16B and OKF6 cells) to Pg or Pg-derived lipopolysaccharides (Pg LPSs) led to rapid loss of endogenous GRHL2 and the junction proteins (e.g., zonula occludens, E-cadherin, claudins, and occludin). GRHL2 directly regulated the expression levels of the junction proteins and the epithelial permeability for small molecules (e.g., dextrans and Pg bacteria). To explore the functional role of GRHL2 in oral mucosal barrier, we used a Grhl2 conditional knockout (KO) mouse model, which allows for epithelial tissue-specific Grhl2 KO in an inducible manner. Grhl2 KO impaired the expression of the junction proteins at the junctional epithelium and increased the alveolar bone loss in the ligature-induced periodontitis model. Fluorescence in situ hybridization revealed increased epithelial penetration of oral bacteria in Grhl2 KO mice compared with the wild-type mice. Also, blood loadings of oral bacteria (e.g., Bacteroides, Bacillus, Firmicutes, β-proteobacteria, and Spirochetes) were significantly elevated in Grhl2 KO mice compared to the wild-type littermates. These data indicate that Pg bacteria may enhance paracellular penetration through oral mucosa in part by targeting the expression of GRHL2 in the oral epithelial cells, which then impairs the epithelial barrier by inhibition of junction protein expression, resulting in increased alveolar tissue destruction and systemic bacteremia.
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Affiliation(s)
- W Chen
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,2 Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, CA, USA
| | - A Alshaikh
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - S Kim
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - J Kim
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - C Chun
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,2 Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, CA, USA
| | - S Mehrazarin
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - J Lee
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - R Lux
- 3 Section of Periodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, CA, USA
| | - R H Kim
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - K H Shin
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - N H Park
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,3 Section of Periodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, CA, USA.,4 Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - K Walentin
- 5 Max Delbruck Center for Molecular Medicine and Department of Nephrology, Charité Medical University, Berlin, Germany
| | - K M Schmidt-Ott
- 5 Max Delbruck Center for Molecular Medicine and Department of Nephrology, Charité Medical University, Berlin, Germany
| | - M K Kang
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,2 Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, CA, USA
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4
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de Boer DV, Brink A, Buijze M, Stigter-van Walsum M, Hunter KD, Ylstra B, Bloemena E, Leemans CR, Brakenhoff RH. Establishment and Genetic Landscape of Precancer Cell Model Systems from the Head and Neck Mucosal Lining. Mol Cancer Res 2018; 17:120-130. [PMID: 30224542 DOI: 10.1158/1541-7786.mcr-18-0445] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/06/2018] [Accepted: 08/21/2018] [Indexed: 11/16/2022]
Abstract
Head and neck squamous cell carcinomas (HNSCC) develop in fields of genetically altered cells. These fields are often dysplastic and a subset can be recognized as (erythro)leukoplakia, but most are macroscopically invisible. There is a lack of adequate treatment options to eradicate these fields, whereas they underlie the development of primary tumors as well as part of the local relapses. Unfortunately, there are almost no representative cellular models available to identify suitable treatment options. To this end, clinical biopsy specimens (n = 98) were cultured from normal appearing mucosa of the surgical margins of patients with primary HNSCCs (n = 32) to generate precancer cell culture models. This collection was extended with six previously established precancer cell cultures. Genetic analysis was performed on cultures with an extended life span (≥20 population doublings), the previously established cultures, and some randomly selected cultures. In total, cancer-associated changes were detected in 18 out of 34 (53%) cultures analyzed, which appeared to be independent of life span. A variety of genetic changes were identified, including somatic mutations as well as chromosomal copy-number aberrations (CNA). Loss of CDKN2A/p16Ink4A and mutations in TP53/p53 were most prominent. Remarkably, in some of these precancer cell cultures only chromosomal CNAs were detected, and none of the frequently occurring driver mutations. IMPLICATIONS: The precancer cell cultures, characterized herein, form a representative collection of field models that can be exploited to identify and validate new therapeutic strategies to prevent primary HNSCCs and local relapses.
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Affiliation(s)
- D Vicky de Boer
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Arjen Brink
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Marijke Buijze
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Marijke Stigter-van Walsum
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Keith D Hunter
- Academic Unit of Oral and Maxillofacial Medicine, Surgery and Pathology, University of Sheffield, South Yorkshire, England
| | - Bauke Ylstra
- Amsterdam UMC, Vrije Universiteit Amsterdam, Pathology, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Elisabeth Bloemena
- Amsterdam UMC, Vrije Universiteit Amsterdam, Pathology, Cancer Center Amsterdam, Amsterdam, the Netherlands.,Department of Maxillofacial Surgery/Oral Pathology, Academic Center for Dentistry Amsterdam (ACTA), Amsterdam, the Netherlands
| | - C René Leemans
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands
| | - Ruud H Brakenhoff
- Amsterdam UMC, Vrije Universiteit Amsterdam, Otolaryngology-Head and Neck Surgery, Cancer Center Amsterdam, Amsterdam, the Netherlands.
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5
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Wagner T, Gschwandtner M, Strajeriu A, Elbe-Bürger A, Grillari J, Grillari-Voglauer R, Greiner G, Golabi B, Tschachler E, Mildner M. Establishment of keratinocyte cell lines from human hair follicles. Sci Rep 2018; 8:13434. [PMID: 30194332 PMCID: PMC6128885 DOI: 10.1038/s41598-018-31829-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 08/28/2018] [Indexed: 12/13/2022] Open
Abstract
The advent of organotypic skin models advanced the understanding of complex mechanisms of keratinocyte differentiation. However, these models are limited by both availability of primary keratinocytes and donor variability. Keratinocytes derived from cultured hair follicles and interfollicular epidermis were immortalized by ectopic expression of SV40 and hTERT. The generated keratinocyte cell lines differentiated into stratified epidermis with well-defined stratum granulosum and stratum corneum in organotypic human skin models. They behaved comparable to primary keratinocytes regarding the expression of differentiation-associated proteins, cell junction components and proteins associated with cornification and formed a barrier against biotin diffusion. Mechanistically, we found that SV40 large T-antigen expression, accompanied by a strong p53 accumulation, was only detectable in the basal layer of the in vitro reconstructed epidermis. Inhibition of DNA-methylation resulted in expression of SV40 large T-antigen also in the suprabasal epidermal layers and led to incomplete differentiation of keratinocyte cell lines. Our study demonstrates the generation of keratinocyte cell lines which are able to fully differentiate in an organotypic skin model. Since hair follicles, as source for keratinocytes, can be obtained by minimally invasive procedures, our approach enables the generation of cell lines also from individuals not available for skin biopsies.
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Affiliation(s)
- Tanja Wagner
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Maria Gschwandtner
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | | | | | - Johannes Grillari
- Evercyte, Vienna, Austria
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
- Christian Doppler Laboratory for Biotechnology of Skin Aging, Vienna, Austria
| | - Regina Grillari-Voglauer
- Evercyte, Vienna, Austria
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Georg Greiner
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Bahar Golabi
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Erwin Tschachler
- Department of Dermatology, Medical University of Vienna, Vienna, Austria.
| | - Michael Mildner
- Department of Dermatology, Medical University of Vienna, Vienna, Austria.
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6
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Chen W, Shin KH, Kim S, Shon WJ, Kim RH, Park NH, Kang MK. hTERT peptide fragment GV1001 demonstrates radioprotective and antifibrotic effects through suppression of TGF‑β signaling. Int J Mol Med 2018; 41:3211-3220. [PMID: 29568955 PMCID: PMC5881842 DOI: 10.3892/ijmm.2018.3566] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/23/2018] [Indexed: 12/12/2022] Open
Abstract
GV1001 is a 16‑amino acid peptide derived from the human telomerase reverse transcriptase (hTERT) protein (616‑626; EARPALLTSRLRFIPK), which lies within the reverse transcriptase domain. Originally developed as an anticancer vaccine, GV1001 demonstrates diverse cellular effects, including anti‑inflammatory, tumor suppressive and antiviral effects. In the present study, the radioprotective and antifibrotic effects of GV1001 were demonstrated through suppressing transforming growth factor‑β (TGF‑β) signaling. Proliferating human keratinocytes underwent premature senescence upon exposure to ionizing radiation (IR), however, treatment of cells with GV1001 allowed the cells to proliferate and showed a reduction in senescent phenotype. GV1001 treatment notably increased the levels of Grainyhead‑like 2 and phosphorylated (p‑)Akt (Ser473), and reduced the activation of p53 and the level of p21/WAF1 in irradiated keratinocytes. It also markedly suppressed the level of TGF‑β signaling molecules, including p‑small mothers against decapentaplegic (Smad)2/3 and Smad4, and TGF‑β target genes, including zinc finger E‑box binding homeobox 1, fibronectin, N‑cadharin and Snail, in irradiated keratinocytes. Furthermore, GV1001 suppressed TGF‑β signaling in primary human fibroblasts and inhibited myofibroblast differentiation. Chromatin immunoprecipitation revealed that GV1001 suppressed the binding of Smad2 on the promoter regions of collagen type III α1 chain (Col3a1) and Col1a1. In a dermal fibrosis model in vivo, GV1001 treatment notably reduced the thickness of fibrotic lesions and the synthesis of Col3a1. These data indicated that GV1001 ameliorated the IR‑induced senescence phenotype and tissue fibrosis by inhibiting TGF‑β signaling and may have therapeutic effects on radiation‑induced tissue damage.
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Affiliation(s)
- Wei Chen
- The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | - Ki-Hyuk Shin
- The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | | | - Won-Jun Shon
- School of Dentistry, Seoul National University, Seoul 03080, Republic of Korea
| | - Reuben H Kim
- The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | - No-Hee Park
- The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | - Mo K Kang
- The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA
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7
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Chen W, Shimane T, Kawano S, Alshaikh A, Kim SY, Chung SH, Kim RH, Shin KH, Walentin K, Park NH, Schmidt-Ott KM, Kang MK. Human Papillomavirus 16 E6 Induces FoxM1B in Oral Keratinocytes through GRHL2. J Dent Res 2018; 97:795-802. [PMID: 29443638 DOI: 10.1177/0022034518756071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
High-risk human papillomavirus (HPV) is a major risk factor for oral and pharyngeal cancers (OPCs), yet the detailed mechanisms by which HPV promotes OPCs are not understood. Forkhead box M1B (FoxM1B) is an oncogene essential for cell cycle progression and tumorigenesis, and it is aberrantly overexpressed in many tumors. We previously showed that FoxM1B was the putative target of an epithelial-specific transcription factor, Grainyhead-like 2 (GRHL2). In the current study, we demonstrate that HPV type 16 (HPV-16) E6 induces FoxM1B in human oral keratinocytes (HOKs) and tonsillar epithelial cells (TECs) in part through GRHL2. FoxM1B was barely detectable in cultured normal human oral keratinocytes (NHOKs) and progressively increased in immortalized HOKs harboring HPV-16 genome (HOK-16B) and tumorigenic HOK-16B/BaP-T cells. Retroviral expression of HPV-16 E6 and/or E7 in NHOKs, TECs, and hypopharyngeal carcinoma cells (FaDu) revealed induction of FoxM1B and GRHL2 by the E6 protein but not E7. Both GRHL2 and FoxM1B were strongly induced in the epidermis of HPV-16 E6 transgenic mice and HPV+ oral squamous cell carcinomas. Ectopic expression of FoxM1B led to acquisition of transformed phenotype in HOK-16B cells. Loss of FoxM1B by lentiviral short hairpin RNA vector or chemical inhibitor led to elimination of tumorigenic characteristics of HOK-16B/BaP-T cells. Luciferase reporter assay revealed that GRHL2 directly bound and regulated the FoxM1B gene promoter activity. Using epithelial-specific Grhl2 conditional knockout mice, we exposed wild-type (WT) and Grhl2 KO mice to 4-nitroquinolin 1-oxide (4-NQO), which led to induction of FoxM1B in the tongue tissues and rampant oral tumor development in the WT mice. However, 4-NQO exposure failed to induce tongue tumors or induction of FoxM1B expression in Grhl2 KO mice. Collectively, these results indicate that HPV-16 induces FoxM1B in part through GRHL2 transcriptional activity and that elevated FoxM1B level is required for oropharyngeal cancer development.
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Affiliation(s)
- W Chen
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - T Shimane
- 2 Department of Dentistry and Oral Surgery, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - S Kawano
- 3 Asahi University School of Dentistry, Gifu, Japan
| | - A Alshaikh
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - S Y Kim
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA
| | - S H Chung
- 4 Deptartment of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - R H Kim
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,5 UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - K H Shin
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,5 UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - K Walentin
- 6 Max Delbruck Center for Molecular Medicine and Department of Nephrology, Charité Medical University, Berlin, Germany
| | - N H Park
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,5 UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
| | - K M Schmidt-Ott
- 6 Max Delbruck Center for Molecular Medicine and Department of Nephrology, Charité Medical University, Berlin, Germany
| | - M K Kang
- 1 The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA, USA.,5 UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
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8
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Liang Z, Kawano S, Chen W, Sadrkhani MS, Lee C, Kim E, Moshaverinia A, Kim RH, Kang MK. Minced Pulp as Source of Pulpal Mesenchymal Stem Cells with Odontogenic Differentiation Capacity. J Endod 2017; 44:80-86. [PMID: 29079051 DOI: 10.1016/j.joen.2017.08.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/24/2017] [Accepted: 08/03/2017] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Pulp tissue regeneration is becoming a reality after discovery of mesenchymal stem cells (MSCs) residing in the pulp tissues through various clinical innovations, although MSC transplantation into the pulp space has met with challenges of in vitro cell expansion and cultures. As a way to circumvent the regulatory and technical complexities of in vitro MSC culture, we investigated the use of minced pulp tissues as a source of pulpal MSCs for tissue regeneration. METHODS We characterized the phenotype of cells explanted from minced pulp (MP), namely MP-derived MSCs (MP-MSCs), compared with dental pulp stem cells (DPSCs) established from pulp tissues by enzyme digestion. Phenotypic characterization included replication kinetics, immunophenotyping, and multilineage differentiation. Using the tooth slice model, we assessed odonto/osteogenic differentiation of DPSCs, MP-MSCs, and minced pulp tissues in situ. RESULTS In vitro replication of MP-MSCs occurred more rapidly during the initial phase of subcultures compared with DPSCs; however, MP-MSCs arrived at senescence at population doubling 47, whereas DPSCs replicated until population doubling 64, indicating shorter replicative lifespan. MP-MSCs also demonstrated stronger odonto/osteogenic differentiation than DPSCs by alkaline phosphatase activity and the protein expression. Both MP-MSCs and DPSCs demonstrated odonto/osteogenic and adipogenic differentiation capacities. Both cell types also showed mineralized tissue formation in the tooth slice model. Seeding minced pulp tissue on poly-L-lactic acid scaffold allowed for migration of MP-MSCs from the tissues and odontogenic differentiation with dentin sialophosphoprotein expression in the tooth slice model. CONCLUSIONS These data indicated that MP may be an alternative source of pulpal MSCs that may allow de novo pulp-dentin regeneration without the need for in vitro culture and expansion.
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Affiliation(s)
- Zhangrui Liang
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California; Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, California
| | - Satoshi Kawano
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California; Asahi University School of Dentistry, Gifu, Japan
| | - Wei Chen
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California; Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, California
| | - Moein Seyed Sadrkhani
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California; Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, California
| | - Chaehwan Lee
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California
| | - Euiseong Kim
- Yonsei University, School of Dentistry, Seoul, Korea
| | - Alireza Moshaverinia
- Division of Advanced Prosthodontics, UCLA School of Dentistry, Los Angeles, California
| | - Reuben H Kim
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California
| | - Mo K Kang
- The Shapiro Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, California; Section of Endodontics, Division of Constitutive and Regenerative Sciences, UCLA School of Dentistry, Los Angeles, California.
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9
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Mavrogonatou E, Pratsinis H, Papadopoulou A, Karamanos NK, Kletsas D. Extracellular matrix alterations in senescent cells and their significance in tissue homeostasis. Matrix Biol 2017; 75-76:27-42. [PMID: 29066153 DOI: 10.1016/j.matbio.2017.10.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/13/2017] [Accepted: 10/14/2017] [Indexed: 12/16/2022]
Abstract
Normal cells after a defined number of successive divisions or after exposure to genotoxic stresses are becoming senescent, characterized by a permanent growth arrest. In addition, they secrete increased levels of pro-inflammatory and catabolic mediators, collectively termed "senescence-associated secretory phenotype". Furthermore, senescent cells exhibit an altered expression and organization of many extracellular matrix components, leading to specific remodeling of their microenvironment. In this review we present the current knowledge on extracellular matrix alterations associated with cellular senescence and critically discuss certain characteristic examples, highlighting the ambiguous role of senescent cells in the homeostasis of various tissues under both normal and pathologic conditions.
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Affiliation(s)
- Eleni Mavrogonatou
- Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Harris Pratsinis
- Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Adamantia Papadopoulou
- Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Nikos K Karamanos
- Biochemistry, Biochemical Analysis & Matrix Pathobiology Research Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Patras, Greece
| | - Dimitris Kletsas
- Laboratory of Cell Proliferation and Ageing, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Athens, Greece.
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10
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Rani S, Bhardwaj S, Srivastava N, Sharma VL, Parsad D, Kumar R. Senescence in the lesional fibroblasts of non-segmental vitiligo patients. Arch Dermatol Res 2017; 309:123-132. [PMID: 28078437 DOI: 10.1007/s00403-016-1713-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/15/2016] [Accepted: 12/23/2016] [Indexed: 01/04/2023]
Abstract
Dermal fibroblasts secrete various growth factors which are important for skin pigmentation. Imbalance in the synchronization of epidermal and dermal cells in the skin can play vital role in the pathogenesis of pigmentary disorder vitiligo. Therefore, our objective was to check the lesional fibroblasts for any abnormality and senescence in non-segmental vitiligo patients (NSV). Skin punch biopsies were taken from NSV patients and healthy controls. Explant culture of fibroblast from lesional dermis, non-lesional dermis, and control was analyzed. The senescence was confirmed by β-galactosidase staining in the cultured fibroblasts. Senescence was checked at mRNA level in lesional dermis, non-lesional dermis of NSV patients by senescence markers p16, p21, and hp1 by quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence study was used for protein analysis. Morphological results showed number of fibroblasts with bigger perinuclear region and vacuoles were more in the lesional fibroblasts. Number of β-galactosidase positive fibroblasts in the lesional skin of NSV patients was higher as compared to the non-lesional and control fibroblasts. Results showed higher relative gene expression of senescence markers p16, p21, and hp1 in the lesional dermis of NSV patients at mRNA level and protein level as compared with control. Senescence in the dermal fibroblasts can decrease the secretion of growth factors and cytokines secreted by fibroblasts which may lead to the melanocyte death and progression of vitiligo. However, further studies on larger number of patients are needed to confirm the role of fibroblasts in the vitiligo pathogenesis.
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Affiliation(s)
- Seema Rani
- Department of Zoology, Panjab University, Chandigarh, 160014, India
| | - Supriya Bhardwaj
- Department of Dermatology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India
| | - Niharika Srivastava
- Department of Dermatology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India
| | | | - Davinder Parsad
- Department of Dermatology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India
| | - Ravinder Kumar
- Department of Zoology, Panjab University, Chandigarh, 160014, India.
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11
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Kang MK, Park NH. Conversion of Normal To Malignant Phenotype: Telomere Shortening, Telomerase Activation, and Genomic Instability During Immortalization of Human Oral Keratinocytes. ACTA ACUST UNITED AC 2016; 12:38-54. [PMID: 11349961 DOI: 10.1177/10454411010120010301] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Normal somatic cells terminate their replicative life span through a pathway leading to cellular senescence, which is triggered by activation of p53 and/or pRb in response to critically shortened telomere DNA. Potentially neoplastic cells must first overcome the senescence checkpoint mechanisms and subsequently activate telomerase to propagate indefinitely. Although telomerase activation is closely associated with cellular immortality, telomerase alone is not sufficient to warrant tumorigenicity. Environmental factors, including chemical carcinogens and viral infection, often contribute to aberrant changes leading to tumorigenic conversion of normal cells. Of particular importance in oral cancer development are tobacco-related chemical carcinogens and human papillomavirus (HPV) infection. To describe the molecular mechanisms by which these environmental factors facilitate the genesis of oral cancer, we first established an in vitro multistep oral carcinogenesis model by sequential exposure of normal human oral keratinocytes (NHOK) to "high risk" HPV and chemical carcinogens. Upon introduction of the HPV genome, the cells bypassed the senescence checkpoint and entered into an extended, but not immortal, life span during which telomere DNA continued to shorten. In a few immortal clones surviving beyond the crisis, we found a marked elevation of telomerase activity and stabilization of telomere length. Furthermore, the E6 and E7 oncoproteins of "high risk" HPV disrupted the cell cycle control and DNA repair in immortalized HOK, and enhanced mutation frequency resulting from genomic instability. However, HPV infection alone failed to give rise to a tumorigenic cell population, which required further exposure to chemical carcinogens in addition to HPV infection. Analysis of the data presented suggests that oral carcinogenesis is a series of discrete genetic alterations that result from a continued genotoxic challenge by environmental risk factors. Our in vitro model may be useful for investigators with interest in furthering our understanding of oral carcinogenesis.
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Affiliation(s)
- M K Kang
- School of Dentistry and Dental Research Institute, University of California, Los Angeles 90095, USA
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12
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Abstract
Progenitor/stem cell populations of epithelium are known to reside in the small-sized cell population. Our objective was to physically isolate and characterize an oral keratinocyte-enriched population of small-sized progenitor/stem cells. Primary human oral mucosal keratinocytes cultured in a chemically defined serum-free culture system, devoid of animal-derived feeder cells, were sorted by relative cell size and characterized by immunolabeling for β1 integrin, nuclear transcription factor, peroxisome proliferator-activated receptor-gamma, and cell-cycle analysis. Sorted cells were distinguished as progenitor/stem cells by functional assays and their ability to regenerate an oral mucosal graft. Small-sized cells demonstrated the lowest expression of peroxisome proliferator-activated receptor-gamma, the highest colony-forming efficiency, a longer long-term proliferative potential, an enriched quiescent cell population, and the ability to regenerate an oral mucosal graft, implying that the small-sized cultured oral keratinocytes contained an enriched population of progenitor/stem cells.
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Affiliation(s)
- K Izumi
- Department of Oral and Maxillofacial Surgery, University of Michigan Health System, B1-208 TC, Box 0018, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0018, USA
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Chen W, Yi JK, Shimane T, Mehrazarin S, Lin YL, Shin KH, Kim RH, Park NH, Kang MK. Grainyhead-like 2 regulates epithelial plasticity and stemness in oral cancer cells. Carcinogenesis 2016; 37:500-10. [PMID: 26933170 PMCID: PMC6118232 DOI: 10.1093/carcin/bgw027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 01/06/2016] [Accepted: 02/20/2016] [Indexed: 12/22/2022] Open
Abstract
Grainyhead-like 2 (GRHL2) is one of the three mammalian homologues of Drosophila Grainyhead involved in epithelial morphogenesis. We recently showed that GRHL2 also controls normal epithelial cell proliferation and differentiation. In this study, we investigated the role of GRHL2 in oral carcinogenesis and the underlying mechanism. GRHL2 expression was elevated in cells and tissues of oral squamous cell carcinomas (OSCCs) compared with normal counterparts. Knockdown of GRHL2 resulted in the loss of in vivo tumorigenicity, cancer stemness and epithelial phenotype of oral cancer cells. GRHL2 loss also inhibited oral cancer cell proliferation and colony formation. GRHL2 regulated the expression of miR-200 family and Octamer-binding transcription factor 4 (Oct-4) genes through direct promoter DNA binding. Overexpression of miR-200 genes in the oral cancer cells depleted of GRHL2 partially restored the epithelial phenotype, proliferative rate and cancer stemness, indicating that miR-200 genes in part mediate the functional effects of GRHL2. Taken together, this study demonstrates a novel connection between GRHL2 and miR-200, and supports protumorigenic effect of GRHL2 on OSCCs.
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Affiliation(s)
- Wei Chen
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Jin Kyu Yi
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA, School of Dentistry, Kyung Hee University, Seoul 130-872, Korea
| | - Tetsu Shimane
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Shebli Mehrazarin
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Yi-Ling Lin
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Ki-Hyuk Shin
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA, Jonsson Comprehensive Cancer Center and
| | - Reuben H Kim
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA, Jonsson Comprehensive Cancer Center and
| | - No-Hee Park
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA, Jonsson Comprehensive Cancer Center and David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Mo K Kang
- School of Dentistry, University of California at Los Angeles, Los Angeles, CA 90095, USA, Jonsson Comprehensive Cancer Center and
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Mehrazarin S, Chen W, Oh JE, Liu ZX, Kang KL, Yi JK, Kim RH, Shin KH, Park NH, Kang MK. The p63 Gene Is Regulated by Grainyhead-like 2 (GRHL2) through Reciprocal Feedback and Determines the Epithelial Phenotype in Human Keratinocytes. J Biol Chem 2015; 290:19999-20008. [PMID: 26085095 DOI: 10.1074/jbc.m115.659144] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Indexed: 11/06/2022] Open
Abstract
In this study, we investigated the effects of p63 modulation in epithelial plasticity in human keratinocytes. The p63 isoforms ΔNp63α, ΔNp63β, and ΔNp63γ were ectopically expressed in normal human epidermal keratinocytes (NHEKs). The epithelial or mesenchymal state was determined by morphological changes and altered expression of various markers, e.g. fibronectin, E-Cadherin, and keratin 14. Overexpression of ΔNp63α and ΔNp63β but not ΔNp63γ isoforms led to morphological changes consistent with epithelial-mesenchymal transition (EMT). However, only ΔNp63α overexpression was able to maintain the morphological changes and molecular phenotype consistent with EMT. Interestingly, knockdown of all p63 isoforms by transfection of p63 siRNA also led to the EMT phenotype, further confirming the role of p63 in regulating the epithelial phenotype in NHEKs. EMT in NHKs accompanied loss of Grainyhead-Like 2 (GHRL2) and miR-200 family gene expression, both of which play crucial roles in determining the epithelial phenotype. Modulation of GRHL2 in NHKs also led to congruent changes in p63 expression. ChIP revealed direct GRHL2 binding to the p63 promoter. GRHL2 knockdown in NHK led to impaired binding of GRHL2 and changes in the histone marks consistent with p63 gene silencing. These data indicate the presence of a reciprocal feedback regulation between p63 and GRHL2 in NHEKs to regulate epithelial plasticity.
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Affiliation(s)
| | | | | | | | - Kyung L Kang
- From the School of Dentistry, the Kyung Hee University, School of Dentistry, Seoul, 130-701, Korea
| | - Jin K Yi
- From the School of Dentistry, the Kyung Hee University, School of Dentistry, Seoul, 130-701, Korea
| | - Reuben H Kim
- From the School of Dentistry, Jonsson Comprehensive Cancer Center, and
| | - Ki-Hyuk Shin
- From the School of Dentistry, Jonsson Comprehensive Cancer Center, and
| | - No-Hee Park
- From the School of Dentistry, the Kyung Hee University, School of Dentistry, Seoul, 130-701, Korea Jonsson Comprehensive Cancer Center, and David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095 and
| | - Mo K Kang
- From the School of Dentistry, Jonsson Comprehensive Cancer Center, and
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15
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Osteo-/Odontogenic Differentiation of Induced Mesenchymal Stem Cells Generated through Epithelial–Mesenchyme Transition of Cultured Human Keratinocytes. J Endod 2014; 40:1796-801. [DOI: 10.1016/j.joen.2014.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 07/06/2014] [Accepted: 07/11/2014] [Indexed: 01/11/2023]
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16
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The cancer stem cell hypothesis applied to oral carcinoma. Oral Oncol 2013; 49:738-46. [PMID: 23642758 DOI: 10.1016/j.oraloncology.2013.04.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/09/2013] [Accepted: 04/09/2013] [Indexed: 12/14/2022]
Abstract
It has been proposed that the development of tumors is based exclusively on the activity of cancer stem cells (CSCs) leading to a new model of carcinogenesis, the CSC hypothesis, in opposition to the conventional model of clonal evolution. The new model may help to explain the high mortality of oral cancer, unchanged over the past decades, the low response to treatment and the tendency of oral squamous cell carcinoma (OSCC) patients to develop multiple tumors. However, a more profound understanding of the molecular pathways involved in maintaining the stem cell (SC) state and of their alterations is required to elucidate the mechanisms underlying the development of tumors and metastatic spread, but research into SC biopathology is hampered by the lack of specific markers for identifying SCs and CSCs in tissues and for establishing topographic relationships with their lineage. We review current knowledge on stem cells in relation to oral cancer, including their possible origins, focusing on the CSC hypothesis of oral tumorigenesis and attempts being made to identify oral stem cells.
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17
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Dong Q, Oh JE, Yi JK, Kim RH, Shin KH, Mitsuyasu R, Park NH, Kang MK. Efavirenz induces autophagy and aberrant differentiation in normal human keratinocytes. Int J Mol Med 2013; 31:1305-12. [PMID: 23563240 PMCID: PMC3692348 DOI: 10.3892/ijmm.2013.1327] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/08/2013] [Indexed: 11/30/2022] Open
Abstract
Although efavirenz (EFV) is efficacious as an anti-retroviral therapy when combined with other antiretroviral drugs, it may cause adverse clinical effects, including skin and mucosal eruptions, central nervous system complications, hepatotoxicity, renal failure and pulmonary complications. The present study investigated the phenotypic alterations caused by EFV in normal human keratinocytes (NHKs) and determined the cell death pathways leading to the lack of epithelial proliferation and regeneration. Replication kinetics, cellular morphology, and protein and mRNA levels of cell cycle regulatory genes and cell death markers were compared between the EFV-exposed cells and the untreated control. EFV treatment led to cell proliferation arrest and cell death of the NHKs by inducing autophagy mediated by proteasome-dependent degradation of p53. EFV also reduced the levels of mTOR and active ERK signaling in NHKs. Chemical inhibition of p53 degradation with a proteasome inhibitor led to reduced autophagic response of NHKs to EFV. In addition, EFV triggered terminal differentiation of NHKs by inducing the expression of involucrin, filaggrin, loricrin and genes involved in cornified envelope formation. Inhibition of autophagy in the EFV-treated NHKs with 3-methylalanine reduced the levels of involucrin and the extent of cell death. Our data indicate that EFV elicits cytotoxic effects on NHKs in part through induction of autophagy and aberrant differentiation of cells.
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Affiliation(s)
- Qinghua Dong
- School of Dentistry, University of California, Los Angeles, CA, USA
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18
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Debacq-Chainiaux F, Leduc C, Verbeke A, Toussaint O. UV, stress and aging. DERMATO-ENDOCRINOLOGY 2013; 4:236-40. [PMID: 23467762 PMCID: PMC3583883 DOI: 10.4161/derm.23652] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Skin is a model of choice in studies on aging. Indeed, skin aging can be modulated by internal and external factors, reflecting its complexity. Two types of skin aging have been identified: intrinsic, mainly genetically determined and extrinsic—also called "photo-aging"—resulting on the impact of environmental stress and more precisely of UV rays. Simplified in vitro models, based on cellular senescence, have been developed to study the relationship between UV and aging. These models vary on the cell type (fibroblasts or keratinocytes, normal or immortalized) and the type of UV used (UVA or UVB).
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19
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Chen W, Xiao Liu Z, Oh JE, Shin KH, Kim RH, Jiang M, Park NH, Kang MK. Grainyhead-like 2 (GRHL2) inhibits keratinocyte differentiation through epigenetic mechanism. Cell Death Dis 2012; 3:e450. [PMID: 23254293 PMCID: PMC3542624 DOI: 10.1038/cddis.2012.190] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We recently identified Grainyhead-like 2 (GRHL2), a mammalian homolog of Grainyhead in Drosophila, to be a novel transcription factor that regulates hTERT gene expression and enhances proliferation of normal human epidermal keratinocytes (NHEK). In the current study, we show that GRHL2 impairs keratinocyte differentiation through transcriptional inhibition of the genes clustered at the epidermal differentiation complex (EDC), located at chromosome 1q21. Gene expression profiling and subsequent in vitro assays revealed consistent downregulation of EDC genes, for example, IVL, KRT1, FLG, LCEs, and SPRRs, in NHEK expressing exogenous GRHL2. In vivo binding assay by chromatin immunoprecipitation revealed GRHL2 association at the promoter regions of its target genes, many of which belong to EDC. Exogenous GRHL2 expression also inhibited recruitment of histone demethylase Jmjd3 to the EDC gene promoters and enhanced the level of histone 3 Lys 27 trimethylation enrichment at these promoters. Survey of GRHL2 expression in human skin tissues demonstrated enhanced protein and mRNA levels in chronic skin lesions with impaired keratinocyte differentiation, for example, atopic dermatitis and psoriasis, compared with normal epidermis. These data indicate that GRHL2 impairs epidermal differentiation by inhibiting EDC gene expression through epigenetic mechanisms and support its role in the hyperproliferative skin diseases.
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Affiliation(s)
- W Chen
- UCLA School of Dentistry, Los Angeles, CA 90095, USA
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20
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1 0 7. Cancer Biomark 2012. [DOI: 10.1201/b14318-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Kriegebaum U, Mildenberger M, Mueller-Richter UD, Klammert U, Kuebler AC, Reuther T. Tissue engineering of human oral mucosa on different scaffolds: in vitro experiments as a basis for clinical applications. Oral Surg Oral Med Oral Pathol Oral Radiol 2012; 114:S190-8. [DOI: 10.1016/j.oooo.2011.10.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/26/2011] [Accepted: 10/04/2011] [Indexed: 11/16/2022]
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22
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Kim RH, Mehrazarin S, Kang MK. Therapeutic potential of mesenchymal stem cells for oral and systemic diseases. Dent Clin North Am 2012; 56:651-75. [PMID: 22835544 PMCID: PMC3426923 DOI: 10.1016/j.cden.2012.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mesenchymal stem cells (MSCs) are adult stem cells whose self-renewal, multipotency, and immunosuppressive functions have been investigated for therapeutic applications. MSCs have used for various systemic organ regenerative therapies, allowing rescue of tissue function in damaged or failing organs. This article reviews the regenerative and immunomodulatory functions of MSCs and their applications in dental, orofacial, and systemic tissue regeneration and treatment of inflammatory disorders. It also addresses challenges to MSC-mediated therapeutics arising from tissue and MSC aging and host immune response against allogenic MSC transplantation, and discusses alternative sources of MSCs aimed at overcoming these limitations.
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Affiliation(s)
- Reuben H. Kim
- Phone: (310) 825-7312, , UCLA School of Dentistry, Division of Restorative Dentistry, 10833 Le Conte Ave., Los Angeles, CA 90095
| | - Shebli Mehrazarin
- , Phone: (310) 267-2810, UCLA School of Dentistry, 10833 Le Conte Ave., Los Angeles, CA 90095
| | - Mo K. Kang
- Jack Weichman Endowed Chair, Phone: (310) 825-8048, , UCLA School of Dentistry, Division of Associated Clinical Specialty, Section of Endodontics, 10833 Le Conte Ave., Los Angeles, CA 90095
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23
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Oh JE, Kim RH, Shin KH, Park NH, Kang MK. DeltaNp63α protein triggers epithelial-mesenchymal transition and confers stem cell properties in normal human keratinocytes. J Biol Chem 2011; 286:38757-38767. [PMID: 21880709 DOI: 10.1074/jbc.m111.244939] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
p63 is a p53 family protein required for morphogenesis and postnatal regeneration of epithelial tissues. Here we demonstrate that ΔNp63α, a p63 isoform lacking the N-terminal transactivation domain, induces epithelial-mesenchymal transition (EMT) in primary human keratinocytes in a TGF-β-dependent manner. Rapidly proliferating normal human epidermal keratinocytes (NHEK) were infected with retroviral vector expressing ΔNp63α or empty vector and serially subcultured until replicative senescence. No phenotypic changes were observed until the culture reached senescence. Then the ΔNp63α-transduced cells underwent morphological changes resembling mesenchymal cells and acquired the EMT phenotype. Treatment with exogenous TGF-β accelerated EMT in presenescent ΔNp63α-transduced cells, whereas the inhibition of TGF-β signaling reversed the EMT phenotype. TGF-β treatment alone led to growth arrest in control NHEK with no evidence of EMT, indicating that ΔNp63α altered the cellular response to TGF-β treatment. ΔNp63α-transduced cells acquiring EMT gained the ability to be differentiated to osteo-/odontogenic and adipogenic pathways, resembling mesenchymal stem cells. Furthermore, these cells expressed enhanced levels of Nanog and Lin28, which are transcription factors associated with pluripotency. These data indicate that EMT required ΔNp63α transduction and intact TGF-β signaling in NHEK.
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Affiliation(s)
- Ju-Eun Oh
- School of Dentistry, UCLA, Los Angeles, California 90095
| | - Reuben H Kim
- School of Dentistry, UCLA, Los Angeles, California 90095; Dental Research Institute, UCLA, Los Angeles, California 90095; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095
| | - Ki-Hyuk Shin
- School of Dentistry, UCLA, Los Angeles, California 90095; Dental Research Institute, UCLA, Los Angeles, California 90095; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095
| | - No-Hee Park
- School of Dentistry, UCLA, Los Angeles, California 90095; Dental Research Institute, UCLA, Los Angeles, California 90095; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095; David Geffen School of Medicine, UCLA, Los Angeles, California 90095
| | - Mo K Kang
- School of Dentistry, UCLA, Los Angeles, California 90095; Dental Research Institute, UCLA, Los Angeles, California 90095; Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California 90095.
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Foxp3 expressed by tongue squamous cell carcinoma cells correlates with clinicopathologic features and overall survival in tongue squamous cell carcinoma patients. Oral Oncol 2011; 47:566-70. [DOI: 10.1016/j.oraloncology.2011.04.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 01/23/2023]
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25
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Shin KH, Pucar A, Kim RH, Bae SD, Chen W, Kang MK, Park NH. Identification of senescence-inducing microRNAs in normal human keratinocytes. Int J Oncol 2011; 39:1205-11. [PMID: 21725593 DOI: 10.3892/ijo.2011.1111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 05/20/2011] [Indexed: 01/01/2023] Open
Abstract
MicroRNAs (miRNAs) are epigenetic regulators of eukaryotic gene expression and play key roles in many cellular processes. However, the role of miRNAs for replicative senescence of normal human keratinocytes (NHKs) remains unknown. Thus, we examined the expression profiles of 847 miRNAs in exponentially replicating and senescent NHKs and identified 126 senescence-associated miRNAs (SA-miRs). Among SA-miRs, 117 miRNAs (93%) were upregulated and 9 miRNAs (7%) were downregulated in senescent NHKs compared to those of exponentially replicating cells. Among the above miRNAs, we selected two miRNAs, miR-137 and miR-668, for further investigation because they were consistently upregulated with replicative senescence of three independent NHK cultures. Ectopic overexpression of miR-137 or miR-668 induced senescence in rapidly proliferating NHKs; a notable increase in senescence-associated β-galactosidase activity, p16INK4A and p53 was observed, indicating that they are novel senescence-inducing miRNAs. In addition, these senescence-inducing miRNAs were gradually increased during organismal aging of normal human oral epithelia. We also detected downregulation of miR-137 and miR-668 in many tested human head and neck squamous cell carcinoma cell lines. Since senescence would be viewed as a potent tumor suppressive pathway, the newly identified senescence-inducing miRNAs deserve to be further investigated for their therapeutic application in cancer treatment.
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Affiliation(s)
- Ki-Hyuk Shin
- School of Dentistry, UCLA, Los Angeles, CA 90024, USA.
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Radioprotective effects of Bmi-1 involve epigenetic silencing of oxidase genes and enhanced DNA repair in normal human keratinocytes. J Invest Dermatol 2011; 131:1216-25. [PMID: 21307872 DOI: 10.1038/jid.2011.11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Normal human keratinocytes (NHKs) undergo premature senescence following exposure to ionizing radiation (IR). This study investigates the effect of Bmi-1, a polycomb group protein, on radiation-induced senescence response. When exposed to IR, NHK transduced with Bmi-1 (NHK/Bmi-1) showed reduced senescent phenotype and enhanced proliferation compared with control cells (NHK/B0). To investigate the underlying mechanism, we determined the production of reactive oxygen species (ROS), expression of ROS-generating enzymes, and DNA repair activities in cells. ROS level was increased upon irradiation but notably reduced by Bmi-1 transduction. Irradiation led to strong induction of oxidase genes, e.g., Lpo (lactoperoxidase), p22-phox, p47-phox, and Gp91, in NHK/B0 but their expression was almost completely silenced in NHK/Bmi-1. Induction of oxidase genes upon irradiation was linked with loss of trimethylated histone 3 at lysine 27 (H3K27Me3), but NHK/Bmi-1 expressed a higher level of H3K27Me3 compared with NHK/B0. Bmi-1 transduction suppressed IR-associated induction of jumanji domain containing 3 while enhancing the expression of EZH2, thereby preventing the loss of H3K27Me3 in the irradiated cells. Furthermore, NHK/Bmi-1 demonstrated increased repair of IR-induced DNA damage compared with NHK/B0. These results indicate that Bmi-1 elicits radioprotective effects on NHK by mitigating the genotoxicity of IR through epigenetic mechanisms.
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Chen W, Dong Q, Shin KH, Kim RH, Oh JE, Park NH, Kang MK. Grainyhead-like 2 enhances the human telomerase reverse transcriptase gene expression by inhibiting DNA methylation at the 5'-CpG island in normal human keratinocytes. J Biol Chem 2010; 285:40852-63. [PMID: 20938050 DOI: 10.1074/jbc.m110.103812] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently identified Grainyhead-like 2 (GRHL2) as a novel transcription factor that binds to and regulates the activity of the human telomerase reverse transcriptase (hTERT) gene promoter. In this study, we investigated the biological functions of GRHL2 and the molecular mechanism underlying hTERT gene regulation by GRHL2. Retroviral transduction of GRHL2 in normal human keratinocytes (NHK) led to a significant extension of replicative life span, whereas GRHL2 knockdown notably repressed telomerase activity and cell proliferation. Using promoter magnetic precipitation coupled with Western blotting, we confirmed the binding of GRHL2 to the hTERT promoter and mapped the minimal binding region at -53 to -13 of the promoter. Furthermore, mutation analysis revealed the three nucleotides from -21 to -19 to be critical for GRHL2 binding. Because hTERT expression is regulated in part by DNA methylation, we determined the effects of GRHL2 on the methylation status of the hTERT promoter. Senescent NHK exhibited hypermethylation of the CpG island, which occurred with the loss of hTERT expression. On the contrary, the promoter remained hypomethylated in GRHL2-transduced NHK, irrespective of cell proliferation status. Also, knockdown of endogenous GRHL2 led to hypermethylation of the promoter. These results indicate that GRHL2 regulates the hTERT expression through an epigenetic mechanism and controls the cellular life span.
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Affiliation(s)
- Wei Chen
- School of Dentistry, UCLA, Los Angeles, California 90095, USA
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Kim RH, Lieberman MB, Lee R, Shin KH, Mehrazarin S, Oh JE, Park NH, Kang MK. Bmi-1 extends the life span of normal human oral keratinocytes by inhibiting the TGF-beta signaling. Exp Cell Res 2010; 316:2600-8. [PMID: 20630502 PMCID: PMC2924923 DOI: 10.1016/j.yexcr.2010.04.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 04/09/2010] [Accepted: 04/10/2010] [Indexed: 01/07/2023]
Abstract
We previously demonstrated that Bmi-1 extended the in vitro life span of normal human oral keratinocytes (NHOK). We now report that the prolonged life span of NHOK by Bmi-1 is, in part, due to inhibition of the TGF-beta signaling pathway. Serial subculture of NHOK resulted in replicative senescence and terminal differentiation and activation of TGF-beta signaling pathway. This was accompanied with enhanced intracellular and secreted TGF-beta1 levels, phosphorylation of Smad2/3, and increased expression of p15(INK4B) and p57(KIP2). An ectopic expression of Bmi-1 in NHOK (HOK/Bmi-1) decreased the level of intracellular and secreted TGF-beta1 induced dephosphorylation of Smad2/3, and diminished the level of p15(INK4B) and p57(KIP2). Moreover, Bmi-1 expression led to the inhibition of TGF-beta-responsive promoter activity in a dose-specific manner. Knockdown of Bmi-1 in rapidly proliferating HOK/Bmi-1 and cancer cells increased the level of phosphorylated Smad2/3, p15(INK4B), and p57(KIP2). In addition, an exposure of senescent NHOK to TGF-beta receptor I kinase inhibitor or anti-TGF-beta antibody resulted in enhanced replicative potential of cells. Taken together, these data suggest that Bmi-1 suppresses senescence of cells by inhibiting the TGF-beta signaling pathway in NHOK.
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Affiliation(s)
- Reuben H. Kim
- UCLA School of Dentistry, Los Angeles, CA 90095
- UCLA Dental Research Institute, Los Angeles, CA 90095
- UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095
| | | | - Rachel Lee
- UCLA School of Dentistry, Los Angeles, CA 90095
| | - Ki-Hyuk Shin
- UCLA School of Dentistry, Los Angeles, CA 90095
- UCLA Dental Research Institute, Los Angeles, CA 90095
- UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095
| | | | - Ju-Eun Oh
- UCLA School of Dentistry, Los Angeles, CA 90095
| | - No-Hee Park
- UCLA School of Dentistry, Los Angeles, CA 90095
- UCLA Dental Research Institute, Los Angeles, CA 90095
- UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Mo K. Kang
- UCLA School of Dentistry, Los Angeles, CA 90095
- UCLA Dental Research Institute, Los Angeles, CA 90095
- UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095
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Liu J, Bian Z, Kuijpers-Jagtman AM, Von den Hoff JW. Skin and oral mucosa equivalents: construction and performance. Orthod Craniofac Res 2010; 13:11-20. [DOI: 10.1111/j.1601-6343.2009.01475.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Yun YG, Jeon BH, Lee JH, Lee SK, Lee HJ, Jung KH, Jun CD, Lee SK, Kim EC. Verticinone induces cell cycle arrest and apoptosis in immortalized and malignant human oral keratinocytes. Phytother Res 2008; 22:416-23. [PMID: 18058993 DOI: 10.1002/ptr.2345] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although verticinone, a major alkaloid isolated from the bulbus of Fritillaria ussuriensis, has been shown to induce differentiation in human leukemia cells, the exact mechanism of this action is not completely understood in cancer cells. Verticinone was used to conduct growth and apoptosis-related experiments for two stages of oral cancer on immortalized human oral keratinocytes (IHOKs) and primary oral cancer cells (HN4). The procedures included MTT assay, three-dimensional (3-D) raft cultures, Western blotting, cell cycle analysis, nuclear staining and cytochrome c expression related to the apoptosis signaling pathway. Verticinone inhibited the proliferation of immortalized and malignant oral keratinocytes in a dose- and time-dependent manner. In 3-D organotypic culture, verticinone-treated cells were less mature than the control cells, displaying low surface keratinization and decreased epithelial thickness. The major mechanism by which verticinone inhibits growth appears to be induced apoptosis and G(0)G(1) cell cycle arrest. This finding is supported by the results of the cell cycle analysis, FITC-Annexin V staining, DNA fragmentation assay and Hoechst 33258 staining. Furthermore, the cytosolic level of cytochrome c was increased, while the expression of Bcl-2 protein was gradually down-regulated and Bax was up-regulated, accompanied by caspase-3 activation. The data suggests that verticinone may induce apoptosis through a caspase pathway mediated by mitochondrial damage in immortalized keratinocytes and oral cancer cells.
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Affiliation(s)
- Young-Gab Yun
- Department of Prescription, College of Oriental Medicine, Wonkwang University, Iksan, South Korea
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31
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Kim RH, Kim R, Chen W, Hu S, Shin KH, Park NH, Kang MK. Association of hsp90 to the hTERT promoter is necessary for hTERT expression in human oral cancer cells. Carcinogenesis 2008; 29:2425-31. [PMID: 18820283 DOI: 10.1093/carcin/bgn225] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Enhanced expression of human telomerase reverse transcriptase (hTERT) occurs frequently during cellular immortalization. The current study was undertaken to determine the mechanism regulating the hTERT promoter activity during cellular immortalization of human oral keratinocytes. Normal human oral keratinocytes (NHOKs) were immortalized with Bmi-1 and the E6 oncoprotein of human papillomavirus type 16 to establish the telomerase-positive HOK-Bmi-1/E6 cell line. Using DNA-protein-binding assay, we found that heat shock protein 90 (hsp90) physically interacts with the hTERT promoter in vitro. The hsp90 interaction with the promoter was detected more strongly in the telomerase-positive HOK-Bmi-1/E6 cells compared with that in senescing NHOK. Chromatin immunoprecipitation confirmed the in vivo interaction between hsp90 and the hTERT promoter in SCC4 cells, a telomerase-positive oral cancer cell line, but not in the NHOK. To determine the physiological significance of this interaction, SCC4 cells were exposed to geldanamycin (GA), a competitive inhibitor of hsp90. GA exposure led to decrease in telomerase activity, hTERT promoter activity and hTERT messenger RNA expression in SCC4 cells, even in the absence of de novo protein synthesis. Also, it abolished the in vivo interaction of the hTERT promoter region with hsp90 but not with Sp1 or c-Myc. These results indicate that physical interaction between hsp90 and the hTERT promoter occurs in telomerase-positive cells but not in normal human cells and is necessary for the enhanced hTERT expression and telomerase activity in cancer cells.
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Affiliation(s)
- Reuben H Kim
- University of California, Los Angeles School of Dentistry, Center for the Health Sciences, Los Angeles, CA 90095, USA
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Hung PS, Kao SY, Liu CJ, Tu HF, Wu CH, Lin SC. Insulin-like growth factor binding protein-5 enhances the migration and differentiation of gingival epithelial cells. J Periodontal Res 2008; 43:673-80. [PMID: 18624948 DOI: 10.1111/j.1600-0765.2007.01070.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND OBJECTIVE The objective was to define the roles of insulin-like growth factor binding protein-5 (IGFBP-5) in gingival epithelial cells (GEC). Human IGFBP-5 is expressed in many cell types and has diverse biological functions. It stimulates the growth of bone cells and is associated with the impedance of gingival fibroblast apoptosis. In gingival epithelium, IGFBP-5 is expressed in the cells of the differentiated stratum spinosum layer. MATERIAL AND METHODS Recombinant IGFBP-5 protein treatment and knockdown of IGFBP-5 expression using a lentivirus-delivered short hairpin RNA was carried out in human GEC. Proliferation, apoptosis, anoikis, migration, differentiation and gene expression in GEC were analyzed and molecular images were obtained. RESULTS The IGFBP-5 had no effect on proliferation, but it slightly suppressed apoptosis and anoikis of GEC. It also induced GEC migration and upregulated the expression of involucrin, transglutaminase-1, keratin and focal adhesion kinase. The IGFBP-5 induced migration partly via an insulin-like growth factor-independent mechanism. The knockdown of IGFBP-5 downregulated the expression of involucrin, transglutaminase-1 and focal adhesion kinase. CONCLUSION Expression of IGFBP-5 in GEC is associated with anti-apoptosis, migration and differentiation of GEC. These phenotypic effects may be associated with focal adhesion kinase and are advantageous for re-epithelization of GEC and the maintenance of gingival health.
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Affiliation(s)
- P-S Hung
- Institute of Oral Biology, School of Dentistry, National Yang-Ming University, Taipei, Taiwan
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33
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Berge U, Kristensen P, Rattan SIS. Hormetic modulation of differentiation of normal human epidermal keratinocytes undergoing replicative senescence in vitro. Exp Gerontol 2008; 43:658-662. [PMID: 18262743 DOI: 10.1016/j.exger.2007.12.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 12/17/2007] [Accepted: 12/21/2007] [Indexed: 01/09/2023]
Abstract
Normal human epidermal keratinocytes (NHEK) show both the Hayflick phenomenon of replicative senescence and differentiation in vitro, depending upon the culture conditions. Using this experimental model system, we have studied age-related changes in the ability of serially passaged NHEK to enter into differentiation in the presence of calcium, as measured by the levels of differentiation markers involucrin, p38 and Hsp27. The results obtained in these studies show that calcium-induced differentiation of NHEK becomes progressively delayed during cellular aging in vitro, which can be modulated by treatments such as mild heat stress, kinetin and curcumin. Whereas all these treatments on their own were able to increase the levels of various differentiation markers to varying extents, their effects were synergistic and rapid in the presence of calcium. Furthermore, all three modulators tested in the present study bring about their effects by inducing stress response pathways in terms of an increase in the levels of stress proteins Hsp90, Hsp70 and heme-oxygenase-1 (HO-1), which is indicative of stress-induced hormesis bringing about the biologically beneficial effects.
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Affiliation(s)
- Ulrich Berge
- Laboratory of Cellular Ageing, Department of Molecular Biology, University of Aarhus, Gustav Wieds vej 10C, DK8000 Aarhus C, Denmark
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34
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Abstract
Normal human somatic cells undergo limited cell division cycles and enter irreversible replication arrest called senescence. Cellular senescence of many human cell types is regulated by the length and status of telomeric sequences, which is shortened after each round of DNA replication. Telomeres can be rejuvenated by telomerase, an enzyme which carries out de novo synthesis of telomeric DNA. Telomerase is a ribonucleoprotein complex composed minimally of telomere reverse transcriptase gene (hTERT) and RNA template (hTR), and its enzyme activity in cells is primarily limited by the level of hTERT expression. Therefore, telomerase activity in cells can be reconstituted by overexpression of hTERT, frequently resulting in extension of replicative life span or immortalization. It is well established that the effect of telomerase reconstitution on cellular life span is clearly cell type-dependent because telomere shortening is not the only limiting factor of cellular life span. However, telomerase activity appears to be a requirement for cellular immortalization, irrespective of the cell types. In this article, we discuss the detailed methods to extend the in vitro replicative life span of primary human cells by ectopic expression of hTERT.
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Affiliation(s)
- Mo K Kang
- School of Dentistry, David Geffen School of Medicine, and Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA
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35
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Kang MK, Kim RH, Kim SJ, Yip FK, Shin KH, Dimri GP, Christensen R, Han T, Park NH. Elevated Bmi-1 expression is associated with dysplastic cell transformation during oral carcinogenesis and is required for cancer cell replication and survival. Br J Cancer 2006; 96:126-33. [PMID: 17179983 PMCID: PMC2360223 DOI: 10.1038/sj.bjc.6603529] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Bmi-1 is a polycomb group protein that was identified as c-myc cooperating oncogene in murine lymphomagenesis. The current study was undertaken to determine the role of Bmi-1 in human oral carcinogenesis. Bmi-1 protein and RNA expression levels were markedly enhanced in the cells of oral squamous cell carcinomas (OSCC) compared with that of normal human oral keratinocytes (NHOK). Enhanced-Bmi-1 expression was also detected in situ in the archived oral mucosal tissues with cancerous and precancerous histopathology, including that of mild epithelial dysplasia. Thus, Bmi-1 expression occurs at a very early stage in oral carcinogenesis. To determine the biological role of Bmi-1 in cell proliferation, endogenous Bmi-1 was knocked down in actively proliferating SCC4 cells and NHOK by RNA interference. After Bmi-1 knockdown, cell replication was severely retarded. However, the expression of p16INK4A, a known cellular target of Bmi-1, was not changed in cells with or without Bmi-1 knockdown. Furthermore, Bmi-1 knockdown in HOK-16B-BaP-T cells, in which the p16INK4A/pRb pathway was abrogated, led to immediate arrest of replication and loss of viable cells. Thus, our data suggest that Bmi-1 may act through p16INK4A-independent pathways to regulate cellular proliferation during oral cancer progression.
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Affiliation(s)
- M K Kang
- UCLA School of Dentistry, Los Angeles, CA 90095, USA.
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36
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Costea DE, Tsinkalovsky O, Vintermyr OK, Johannessen AC, Mackenzie IC. Cancer stem cells – new and potentially important targets for the therapy of oral squamous cell carcinoma. Oral Dis 2006; 12:443-54. [PMID: 16910914 DOI: 10.1111/j.1601-0825.2006.01264.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
There is increasing evidence that the growth and spread of cancers is driven by a small subpopulation of cancer stem cells (CSCs) - the only cells that are capable of long-term self-renewal and generation of the phenotypically diverse tumour cell population. Current failure of cancer therapies may be due to their lesser effect on potentially quiescent CSCs which remain vital and retain their full capacity to repopulate the tumour. Treatment strategies for the elimination of cancer therefore need to consider the consequences of the presence of CSCs. However, the development of new CSC-targeted strategies is currently hindered by the lack of reliable markers for the identification of CSCs and the poor understanding of their behaviour and fate determinants. Recent studies of cell lines derived from oral squamous cell carcinoma (OSCC) indicate the presence of subpopulations of cells with phenotypic and behavioural characteristics corresponding to both normal epithelial stem cells and to cells capable of initiating tumours in vivo. The present review discusses the relevance to OSCC of current CSC concepts, the state of various methods for CSC identification, characterization and isolation (clonal functional assay, cell sorting based on surface markers or uptake of Hoechst dye), and possible new approaches to therapy.
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Affiliation(s)
- D E Costea
- Bergen Oral Cancer Group, Department of Oral Sciences, Oral Pathology and Forensic Odontology, University of Bergen, Bergen, Norway.
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37
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Sdek P, Zhang ZY, Cao J, Pan HY, Chen WT, Zheng JW. Alteration of cell-cycle regulatory proteins in human oral epithelial cells immortalized by HPV16 E6 and E7. Int J Oral Maxillofac Surg 2006; 35:653-7. [PMID: 16513324 DOI: 10.1016/j.ijom.2006.01.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 08/08/2005] [Accepted: 01/16/2006] [Indexed: 11/18/2022]
Abstract
E6 and E7 oncoproteins from high-risk human papillomavirus (HPV) can transform cells in tissue culture and induce tumors in vivo by abrogating the cell-cycle checkpoint. To investigate the impact of HPV16 E6 and E7 on the cell-cycle regulatory machinery in oral epithelial cells, normal human oral epithelial cells were transfected with HPV16 E6 and E7 open reading frames, and alterations in cell-cycle regulatory proteins in cells expressing HPV16 E6 and E7 were analyzed. E6 and E7 expression results in immortalization of oral epithelial cells. E7 inactivates retinoblastoma protein (Rb) by forming complexes with hypophosphorylated Rb in immortalized oral epithelial cells. P53 and P21 protein levels were increased in immortalized cells compared to normal primary oral epithelial cells. Cyclin D1-cell-cycle-dependent kinase 4 binary association is disrupted in immortalized oral epithelial cells. These results indicate that E7 plays an important role in abrogation of cell-cycle regulation in oral epithelial cells, with E6 having a smaller impact. This suggests that the pathogenesis of HPV in oral epithelial cells differs from that in cervical epithelial cells.
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Affiliation(s)
- P Sdek
- School of Stomatology, Shanghai Second Medical University, 639 Zhi-Zao-Ju Road, Shanghai 200011, PR China
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38
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Onda T, Uzawa K, Endo Y, Bukawa H, Yokoe H, Shibahara T, Tanzawa H. Ubiquitous mitochondrial creatine kinase downregulated in oral squamous cell carcinoma. Br J Cancer 2006; 94:698-709. [PMID: 16479256 PMCID: PMC2361206 DOI: 10.1038/sj.bjc.6602986] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In this study, we performed two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionisation time of fly mass spectrometry to identify the protein(s) associated with the development of oral squamous cell carcinomas (OSCCs) by comparing patterns of OSCC-derived cell lines with normal oral keratinocytes (NOKs), and found that downregulation of ubiquitous mitochondrial creatine kinase (CKMT1) could be a good candidate. Decreased levels of CKMT1 mRNA and protein were detected in all OSCC-derived cell lines examined (n=9) when compared to those in primary normal oral keratinocytes. Although no sequence variation in the coding region of the CKMT1 gene with the exception of a nonsense mutation in exon 8 was identified in these cell lines, we found a frequent hypermethylation in the CpG island region. CKMT1 expression was restored by experimental demethylation. In addition, when we transfected CKMT1 into the cell lines, they showed an apoptotic phenotype but no invasiveness. In clinical samples, high frequencies of CKMT1 downregulation were detected by immunohistochemistry (19 of 52 (37%)) and quantitative real-time RT-PCR (21 of 50 (42%)). Furthermore, the CKMT1 expression status was significantly correlated with tumour differentiation (P<0.0001). These results suggest that the CKMT1 gene is frequently inactivated during oral carcinogenesis and that an epigenetic mechanism may regulate loss of expression, which may lead to block apoptosis.
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MESH Headings
- Apoptosis
- Carcinoma, Squamous Cell/enzymology
- Carcinoma, Squamous Cell/genetics
- Cell Line, Tumor
- CpG Islands
- Creatine Kinase, Mitochondrial Form/biosynthesis
- Creatine Kinase, Mitochondrial Form/genetics
- DNA Methylation
- Down-Regulation
- Electrophoresis, Gel, Two-Dimensional
- Exons
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- Humans
- Immunohistochemistry
- Keratinocytes/enzymology
- Mouth Neoplasms/enzymology
- Mouth Neoplasms/genetics
- RNA, Messenger/analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Affiliation(s)
- T Onda
- Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, 1-2-2 Masago, Mihama-ku Chiba 261-8502, Japan
| | - K Uzawa
- Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku Chiba 260-8670, Japan
- Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku Chiba 260-8677, Japan
- Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku Chiba 260-8670, Japan; E-mail:
| | - Y Endo
- Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku Chiba 260-8670, Japan
| | - H Bukawa
- Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku Chiba 260-8677, Japan
| | - H Yokoe
- Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku Chiba 260-8677, Japan
| | - T Shibahara
- Department of Oral and Maxillo-Facial Surgery, Tokyo Dental College, 1-2-2 Masago, Mihama-ku Chiba 261-8502, Japan
| | - H Tanzawa
- Department of Clinical Molecular Biology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku Chiba 260-8670, Japan
- Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku Chiba 260-8677, Japan
- The 21st Century Center of Excellence (COE) program, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku Chiba 260-8670, Japan
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39
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Kang MK, Kim RH, Shin KH, Zhong W, Faull KF, Park NH. Senescence-associated decline in the intranuclear accumulation of hOGG1-alpha and impaired 8-oxo-dG repair activity in senescing normal human oral keratinocytes in vivo. Exp Cell Res 2005; 310:186-95. [PMID: 16122734 DOI: 10.1016/j.yexcr.2005.07.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 07/12/2005] [Accepted: 07/21/2005] [Indexed: 11/30/2022]
Abstract
We determined the mitochondrial membrane status, presence of reactive oxygen species (ROS), and oxidative DNA adduct formation in normal human oral keratinocytes (NHOK) during senescence. The senescent cells showed accumulation of intracellular ROS and 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG), a major oxidative DNA adduct. Exposure of cells to H2O2 induced 8-oxo-dG accumulation in cellular DNA, which was rapidly removed in replicating NHOK. However, the 8-oxo-dG removal activity was almost completely abolished in the senescing culture. Both replicating and senescing NHOK expressed readily detectable 8-oxo-dG DNA glycosylase (hOGG1), the enzyme responsible for glycosidic cleavage of 8-oxo-dG. After exposure to H2O2, however, the intranuclear level of the hOGG1-alpha isoform was decreased in senescing but not in replicating NHOK. These results indicated that senescing NHOK accumulated oxidative DNA lesions in part due to increased level of endogenous ROS and impaired intranuclear translocation of hOGG1 enzyme upon exposure to oxidative stress.
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Affiliation(s)
- Mo K Kang
- UCLA School of Dentistry, CHS 43-009, 10833 Le Conte Avenue, Los Angeles, CA 90095-1668, USA.
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Cai S, Fatherazi S, Presland RB, Belton CM, Izutsu KT. TRPC channel expression during calcium-induced differentiation of human gingival keratinocytes. J Dermatol Sci 2005; 40:21-8. [PMID: 16051466 DOI: 10.1016/j.jdermsci.2005.06.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2005] [Revised: 05/28/2005] [Accepted: 06/09/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Extracellular calcium is an important regulator of keratinocyte differentiation. An increase in intracellular calcium ion concentration is required for activation of calcium-induced keratinocyte differentiation. The signaling elements in this differentiation response include the calcium sensing receptor, phospholipase C, release of calcium ions from intracellular stores, and store-operated calcium channels. Nothing is currently known about the calcium-entry channels activated by the increase in external calcium. However, canonical transient receptor potential (TRPC) channels have been identified as store-operated calcium channels in several tissues. OBJECTIVE To examine the expression of TRPC channels in human gingival keratinocytes (HGKs) in primary culture under both low calcium (basal) and high calcium (differentiating) conditions, and in gingival tissue. METHODS TRPC channel expression was evaluated via RT-PCR, Western blots, and immunohistology. RESULTS TRPC1, TRPC5, TRPC6 and TRPC7 mRNAs were detected in undifferentiated keratinocytes. Their levels initially increased, then decreased during calcium-induced differentiation. TRPC1 and TRPC6 protein expression reflected these changes. CONCLUSION TRPC channels are present in both proliferating and differentiating keratinocytes in primary culture and in gingival tissue. The above expression patterns suggest that these channels may be involved in calcium-induced differentiation of keratinocytes.
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Affiliation(s)
- Shiwei Cai
- Department of Oral Biology, University of Washington, Box 357132, Seattle, WA 98195-6524, USA
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41
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Kang MK, Shin KH, Yip FK, Park NH. Normal human oral keratinocytes demonstrate abnormal DNA end joining activity during replicative senescence. Mech Ageing Dev 2005; 126:475-9. [PMID: 15722106 DOI: 10.1016/j.mad.2004.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 09/30/2004] [Accepted: 10/13/2004] [Indexed: 11/30/2022]
Abstract
Repair of DNA double-strand breaks (DSBs) is critical for the maintenance of cellular genetic integrity. DSBs are repaired by cellular end joining activity, which could proceed with varying degrees of accuracy. Abnormal end joining may lead to an accumulation of mutations and contribute to genetic instability and cellular aging. In the present study, we compared the efficiency and accuracy of end joining activities in exponentially replicating and senescing normal human oral keratinocytes (NHOK). We developed an in vitro end joining assay utilizing a plasmid linearized with a unique EcoR I or EcoR V restriction site. The efficiency of end joining was determined by PCR with primers that could amplify the fragment containing the end joining site. The accuracy of end joining was assessed by determining whether the original EcoR I site was restored after end joining. Both replicating and senescing cultures of NHOK yielded a similar level of end joining efficiency, which was noted by the similar intensity of PCR amplification. However, the frequency of end joining errors was significantly elevated in NHOK during replicative senescence. Senescing NHOK could thus accumulate abnormal end joining products, which might contribute to cellular aging and cancer.
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Affiliation(s)
- Mo K Kang
- School of Dentistry, University of California, Los Angeles, UCLA, CHS 53-038, 10833 Le Conte Avenue, Los Angeles, CA 90095-1668, USA
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42
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Kang MK, Kameta A, Shin KH, Baluda MA, Park NH. Senescence occurs with hTERT repression and limited telomere shortening in human oral keratinocytes cultured with feeder cells. J Cell Physiol 2004; 199:364-70. [PMID: 15095283 DOI: 10.1002/jcp.10410] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We investigated the phenotypic and molecular alterations in normal human oral keratinocytes (NHOK) during in vitro replication in two different culture conditions. The cells were cultured either in chemically defined Keratinocyte Growth Medium (KGM) without feeder layers or in serum-containing flavin-adenine dinucleotide (FAD) medium with feeder layers. Primary NHOK underwent 22 +/- 3 population doublings (PDs) in KGM and 42 +/- 4 PDs in FAD medium, reflecting 52% increase in replication capacity with feeder layers. In both culture conditions, exponentially replicating NHOK demonstrated telomerase activity and expression of human telomerase reverse transcriptase (hTERT) gene. Telomerase activity and hTERT expression were rapidly diminished in senescing NHOK, which exhibited small decrease of telomere length for the remaining limited cellular replications until the complete arrest of cell division. However, telomere length in senescent NHOK was 6.7 +/- 0.5 kilobase pairs (kbps), significantly longer than that (5.12 kbps) of senescent human fibroblasts. The onset of senescence was accompanied with marked induction of p16(INK4A), and this occurred in both culture systems using either KGM or FAD medium. These results indicate that replicative senescence of NHOK is associated with loss of telomerase activity followed by limited telomere shortening.
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Affiliation(s)
- Mo K Kang
- School of Dentistry, University of California, Los Angeles, California 90095, USA.
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Mohamed KM, Le A, Duong H, Wu Y, Zhang Q, Messadi DV. Correlation between VEGF and HIF-1alpha expression in human oral squamous cell carcinoma. Exp Mol Pathol 2004; 76:143-52. [PMID: 15010293 DOI: 10.1016/j.yexmp.2003.10.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2003] [Indexed: 11/21/2022]
Abstract
Understanding the development and progression of oral cancer is critical in the quest for successful therapeutic intervention. The hypoxic microenvironment present in human oral tumor in vivo may actively influence tumor growth and neovascularization. This study correlates expression of both VEGF and HIF-1alpha in normal keratinocytes and oral cancer cell lines and determine whether hypoxia played a role in VEGF and HIF-1alpha regulation. Three human oral cancer cell lines and three normal keratinocytes were exposed to both normoxia and hypoxia culture conditions. Northern and Western blot analysis were used to assess VEGF and HIF-1alpha expression in the different culture conditions. ELISA assays were performed to measure VEGF production in the different cell lines tested. Hypoxia upregulated VEGF and HIF-1alpha expression on both normal and oral cancer cell lines, with a statistically significant difference between normal and oral cancer cell lines. Pattern of hypoxia-induced VEGF mRNA level tightly followed the HIF-1alpha mRNA expression in the cell lines tested. These results suggest that hypoxia regulates both VEGF and HIF-1alpha expression in head and neck carcinoma cell lines, thus establishing a biochemical pathway between tumor hypoxia and neoangiogenesis in these aggressive neoplasms.
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44
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Golubev A, Khrustalev S, Butov A. An in silico investigation into the causes of telomere length heterogeneity and its implications for the Hayflick limit. J Theor Biol 2004; 225:153-70. [PMID: 14575650 DOI: 10.1016/s0022-5193(03)00229-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
UNLABELLED In telomerase-negative cell populations the mean telomere length (TL) decreases with increasing population doubling number (PD). A critically small TL is believed to stop cell proliferation at a cell-, age- and species-specific PD thus defining the Hayflick limit. However, positively skewed TL distributions are broad compared to differences between initial and final mean TL and strongly overlap at middle and late PD, which is inconsistent with a limiting role of TL. We used computer-assisted modelling to define what set of premises may account for the above. Our model incorporates the following concepts. DNA end replication problem: telomeres loose 1 shortening unit (SU) upon each cell division. Free radical-caused TL decrease: telomeres experience random events resulting in the loss of a random SU number within a remaining TL. Stochasticity of gene expression and cell differentiation: cells experience random events inducing mitoses or committing cells to proliferation arrest, the latter option requiring a specified number of mitoses to be passed. Cells whose TL reaches 1SU cannot divide. The proliferation kinetics of such virtual cells conforms to the transition probability model of cell cycle. When no committing events occur and at realistic SU estimates of the initial TL, maximal PD values far exceed the Hayflick limit observed in normal cells and are consistent with the crisis stage entered by transformed cells that have surpassed the Hayflick limit. At intermediate PD, symmetrical TL distributions are yielded. Upon introduction of committing events making the ratio of the rates of proliferating and committing events (P/C) range from 1.10 to 1.25, TL distributions at intermediate PD become positively skewed, and virtual cell clones show bimodal size distributions. At P/C as high as 1.25 the majority of virtual cells at maximal PD contain telomeres with TL>1SU. A 10% increase in P/C within the 1.10-1.25 range produces a two-fold increase in the maximal PD, which can reach values of up to 25 observed in rodent and some human cells. Increasing the number of committed mitoses from 0 to 10 can increases PD to about 50 observed in human fibroblasts. Introduction of the random TL breakage makes the shapes of TL distributions quite dissimilar from those observed in real cells. CONCLUSIONS Telomere length decrease is a correlate of cell proliferation that cannot alone account for the Hayflick limit, which primarily depends on parameters of cell population kinetics. Free radical damage influences the Hayflick limit not through TL but rather by affecting the ratio of the rates of events that commit cells to mitoses or to proliferation arrest.
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Affiliation(s)
- A Golubev
- Research Institute of Experimental Medicine, St. Petersburg, Russia.
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45
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Manni V, Lisi A, Rieti S, Serafino A, Ledda M, Giuliani L, Sacco D, D'Emilia E, Grimaldi S. Low electromagnetic field (50 Hz) induces differentiation on primary human oral keratinocytes (HOK). Bioelectromagnetics 2004; 25:118-26. [PMID: 14735562 DOI: 10.1002/bem.10158] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This work concerns the effect of low frequency electromagnetic fields (ELF) on biochemical properties of human oral keratinocytes (HOK). Cells exposed to a 2 mT, 50 Hz, magnetic field, showed by scanning electron microscopy (SEM) modification in shape and morphology; these modifications were also associated with different actin distribution, revealed by phalloidin fluorescence analysis. Moreover, exposed cells had a smaller clonogenic capacity, and decreased cellular growth. Indirect immunofluorescence with fluorescent antibodies against involucrin and beta-catenin, both differentiation and adhesion markers, revealed an increase in involucrin and beta-catenin expression. The advance in differentiation was confirmed by a decrease of expression of epidermal growth factor (EGF) receptor in exposed cells, supporting the idea that exposure to electromagnetic field carries keratinocytes to higher differentiation level. These observations support the hypothesis that 50 Hz electromagnetic fields may modify cell morphology and interfere in differentiation and cellular adhesion of normal keratinocytes.
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Affiliation(s)
- Vanessa Manni
- Istituto di Neurobiologia e Medicina Molecolare (INeMM), CNR, Rome, Italy
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46
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Shin KH, Kang MK, Dicterow E, Park NH. Hypermethylation of the hTERT promoter inhibits the expression of telomerase activity in normal oral fibroblasts and senescent normal oral keratinocytes. Br J Cancer 2003; 89:1473-8. [PMID: 14562019 PMCID: PMC2394329 DOI: 10.1038/sj.bjc.6601291] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Telomerase activity in human cells closely correlates with the expression of its catalytic subunit, telomerase reverse transcriptase (hTERT). Previously, we reported the lack of telomerase activity in normal human oral fibroblasts (NHOF) and the diminution of telomerase activity during senescence in normal human oral keratinocytes (NHOK). To investigate the underlying mechanisms of telomerase regulation in both cell types, we analysed the expression, promoter activity, and methylation status of the hTERT gene. The expression of hTERT mRNA diminished in senescent NHOK, but was not detected in NHOF at any stage of replication. An exogenous hTERT promoter was active in NHOF and in senescing NHOK, indicating that the lack of hTERT gene expression resulted from alteration of the endogenous hTERT promoter. Since methylation is involved in the silencing of numerous genes, we carried out DNA methylation assays. The assay revealed that the hTERT promoter was hypermethylated in NHOF and was gradually methylated during senescence in NHOK. Treatment of NHOF and senescent NHOK with the demethylating agent 5-aza-2′-deoxycytidine restored the expression of endogenous hTERT mRNA. Our results suggest that hypermethylation of the hTERT promoter plays a critical role in the negative regulation of telomerase activity in normal human oral cells.
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Affiliation(s)
- K-H Shin
- School of Dentistry, University of California, Los Angeles, CA, USA
| | - M K Kang
- School of Dentistry, University of California, Los Angeles, CA, USA
| | - E Dicterow
- School of Dentistry, University of California, Los Angeles, CA, USA
| | - N-H Park
- School of Dentistry, University of California, Los Angeles, CA, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA
- UCLA School of Dentistry, CHS 53-038, 10833 Le Conte Ave. Los Angeles, CA 90095-1668, USA. E-mail:
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Ookura T, Kawamoto K, Tsuzaki H, Mikami Y, Ito Y, Oh SL, Hino A. Fibroblast and epidermal growth factors modulate proliferation and neural cell adhesion molecule expression in epithelial cells derived from the adult mouse tongue. In Vitro Cell Dev Biol Anim 2002; 38:365-72. [PMID: 12513125 DOI: 10.1290/1071-2690(2002)038<0365:faegfm>2.0.co;2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Lingual epithelial cells, including those of the taste buds, are regularly replaced by proliferative stem cells. We found that integrin beta(1), a keratinocyte stem cell marker, was expressed at the basal layer and taste buds of adult mouse tongue epithelium. We purified and cultured integrin beta(1)-positive cells (termed KT-1 cells), whose growth was stimulated by epidermal growth factor (EGF) and basic fibroblast growth factor (FGF-2). FGF-2 stimulation induced translocation of the FGF type I receptor (FGFR1) into nuclei, suggesting that the growth-stimulating effect of FGF-2 was mediated through FGFR1. EGF and FGF-2 also regulated cell surface expression of the neural cell adhesion molecule (N-CAM) in KT-1 cells. Anti-N-CAM antibody immunoreactivity was restricted to the gustatory epithelium and the nerves in the tongue epithelium, giving rise to the possibility that KT-1 may contain gustatory epithelial cells. KT-1 cells may thus be useful for analyzing the factors that regulate the growth and differentiation of lingual and gustatory epithelial cells in vitro.
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Affiliation(s)
- Tetsuya Ookura
- National Food Research Institute, 2-1-12 Kan-nondai, Tsukuba, Ibaraki 305-8642, Japan.
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Kang MK, Swee J, Kim RH, Baluda MA, Park NH. The telomeric length and heterogeneity decrease with age in normal human oral keratinocytes. Mech Ageing Dev 2002; 123:585-92. [PMID: 11850022 DOI: 10.1016/s0047-6374(01)00407-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We have examined the telomere length in NHOK explanted from 28 donors between the ages of 21 and 84 years. Genomic DNA was isolated from exponentially replicating NHOK and digested with HinFI to yield terminal restriction fragments (TRF). The TRF length ranged from 4.1 to 7.0 kbp with a mean of 5.3 +/- 0.8 kbp, which was significantly shorter than that (8.9 +/- 1.0 kbp) of normal human oral fibroblasts (NHOF). The TRF length was inversely correlated to the increase of donor age in NHOK (m=-23 bp per year; r=-0.60; P<0.001). Also, the heterogeneity of TRF length in cultured NHOK decreased with increased donor age (r=-0.38, P<0.05). These data indicated that clonogenic NHOK cells had replicated in situ and showed a progressive shortening of TRF length. The short telomere length and decreased telomeric length heterogeneity in immortalized cells suggested that there is a critical minimum for cell survival.
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Affiliation(s)
- Mo K Kang
- Dental Research Institute, University of California, 73-017 CHS, 10833 Le Conte Avenue, Los Angeles, CA 90095-1668, USA
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49
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Whyte DA, Broton CE, Shillitoe EJ. The unexplained survival of cells in oral cancer: what is the role of p53? J Oral Pathol Med 2002; 31:125-33. [PMID: 11903817 DOI: 10.1034/j.1600-0714.2002._310301.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In normal oral epithelium the cells divide, mature, differentiate, and die. This sequence is not normally followed in oral cancer. Instead, the death of the cells is somehow prevented, although the pathways toward cell death in normal oral epithelium and the defects in oral cancer are not well defined. However, several components in the system have been identified, and information on their interactions is becoming available. This review summarizes the evidence for cell death being due to apoptosis and the central role of the p53 gene product in its regulation. Areas for future research are also identified.
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50
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Althaus HH, Mursch K, Klöppner S. Differential response of mature TrkA/p75(NTR) expressing human and pig oligodendrocytes: aging, does it matter? Microsc Res Tech 2001; 52:689-99. [PMID: 11276121 DOI: 10.1002/jemt.1053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A differential morphological response of mature oligodendrocytes (OL) isolated from human and pig brains to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and to the nerve growth factor (NGF) was observed. In both cases, OL regenerate their processes; however, the rate and the extension of the process formation of human OL were behind that of pig OL. Presumably, the advanced age of the human tissue in these experiments might have contributed to this decrease in process formation, an effect that was already observed for rat OL [Yong et al. (1991) J Neurosci Res 29:87-99]. The less effectivity of NGF via TrkA, which was immunocytochemically shown in human OL, and of TPA via the protein kinase C (PKC) pathway, may have its common focus on the mitogen-activated protein kinase (MAPK) cascade. In this context, it was noted that only a few studies on aging of mature OL are available. It is conceivable that age-related changes in the properties of OL could be an important factor for their cellular responsiveness during longer lasting demyelinating diseases such as multiple sclerosis. Hence, this review would like to provide a basis for future investigations on the aging of mature OL. The data presently available suggest a preliminary classification of mature OL into three categories.
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Affiliation(s)
- H H Althaus
- Max-Planck-Institute for Experimental Medicine, AG Neural Regeneration, H-Reinstr. 3, D-37075 Göttingen, Germany.
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