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Wang Y, Chen S, Yan Z, Pei M. A prospect of cell immortalization combined with matrix microenvironmental optimization strategy for tissue engineering and regeneration. Cell Biosci 2019; 9:7. [PMID: 30627420 PMCID: PMC6321683 DOI: 10.1186/s13578-018-0264-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/21/2018] [Indexed: 12/20/2022] Open
Abstract
Cellular senescence is a major hurdle for primary cell-based tissue engineering and regenerative medicine. Telomere erosion, oxidative stress, the expression of oncogenes and the loss of tumor suppressor genes all may account for the cellular senescence process with the involvement of various signaling pathways. To establish immortalized cell lines for research and clinical use, strategies have been applied including internal genomic or external matrix microenvironment modification. Considering the potential risks of malignant transformation and tumorigenesis of genetic manipulation, environmental modification methods, especially the decellularized cell-deposited extracellular matrix (dECM)-based preconditioning strategy, appear to be promising for tissue engineering-aimed cell immortalization. Due to few review articles focusing on this topic, this review provides a summary of cell senescence and immortalization and discusses advantages and limitations of tissue engineering and regeneration with the use of immortalized cells as well as a potential rejuvenation strategy through combination with the dECM approach.
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Affiliation(s)
- Yiming Wang
- 1Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, PO Box 9196, 64 Medical Center Drive, Morgantown, WV 26506-9196 USA.,2Department of Orthopaedics, Zhongshan Hospital of Fudan University, 180 Fenglin Road, Shanghai, 200032 China
| | - Song Chen
- 3Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083 Sichuan China
| | - Zuoqin Yan
- 2Department of Orthopaedics, Zhongshan Hospital of Fudan University, 180 Fenglin Road, Shanghai, 200032 China
| | - Ming Pei
- 1Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University, PO Box 9196, 64 Medical Center Drive, Morgantown, WV 26506-9196 USA.,4WVU Cancer Institute, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506 USA
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2
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Tzenov YR, Andrews PG, Voisey K, Popadiuk P, Xiong J, Popadiuk C, Kao KR. Human papilloma virus (HPV) E7-mediated attenuation of retinoblastoma (Rb) induces hPygopus2 expression via Elf-1 in cervical cancer. Mol Cancer Res 2013; 11:19-30. [PMID: 23284001 DOI: 10.1158/1541-7786.mcr-12-0510] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The human papillomavirus (HPV) is the etiologic agent of cervical cancer. In this study, we provide evidence for the human Pygopus (hPygo)2 gene as a cellular biomarker for HPV-related disease. In a tumor microarray of cervical cancer progression, hPygo2 levels were greater in high-grade lesions and squamous cell carcinomas than in normal epithelia. Similarly, hPygo2 mRNA and protein levels were greater in HPV-positive cervical cancer cells relative to uninfected primary cells. RNA interference (RNAi)-mediated depletion of HPV-E7 increased whereas E74-like factor (Elf)-1 RNAi decreased association of Retinoblastoma (Rb) tumor suppressor with the hPygo2 promoter in cervical cancer cell lines. Transfection of dominant-active Rb inhibited Elf-1-dependent activation of hPygo2, whereas Elf-1 itself increased hPygo2 expression. Chromatin immunoprecipitation assays showed that Rb repressed hPygo2 by inhibiting Elf-1 at the Ets-binding site in the hPygo2 promoter. These results suggested that abrogation of Rb by E7 resulted in derepression of Elf-1, which in turn stimulated expression of hPygo2. Thus, initiation of hPygo2 expression by Elf-1 was required for proliferation of cervical cancer cells and its expression therefore may act as a surrogate marker for dysplasia.
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Affiliation(s)
- Youlian R Tzenov
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, NL, Canada, A1B 3V6
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3
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Prokopczyk B, Sinha I, Trushin N, Freeman WM, El-Bayoumy K. Gene expression profiles in HPV-immortalized human cervical cells treated with the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Chem Biol Interact 2008; 177:173-80. [PMID: 19038236 DOI: 10.1016/j.cbi.2008.10.051] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 10/21/2008] [Accepted: 10/22/2008] [Indexed: 10/21/2022]
Abstract
Human papillomavirus (HPV) infection is an established etiological factor for cervical cancer. Epidemiological studies suggest that smoking in combination with HPV infection plays a significant role in the etiology of this disease. We have previously shown that the tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is present in human cervical mucus. Here, we hypothesized that treatment of HPV-16-immortalized human ectocervical cells (Ecto1/E6E7) with NNK would alter the expression of genes involved in cellular transformation. Ecto1/E6E7 cells were treated with water (vehicle control) alone or with 1 microM, 10 microM, and 100 microM of NNK in water for 12 weeks. The colony-forming efficiency increased following NNK treatment; the maximum effect was observed after 12 weeks with 100 microM NNK. Microarray analysis revealed that, independent of the dose of NNK, expression of 30 genes was significantly altered; 22 of these genes showed a dose-response pattern. Genes identified are categorized as immune response (LTB4R), RNA surveillance pathway (SMG1), metabolism (ALDH7A1), genes frequently expressed in later stages of neoplastic development (MT1F), DNA binding (HIST3H3 and CHD1L), and protein biosynthesis (UBA52). Selected genes were confirmed by qRT-PCR. Western blot analysis indicates that phosphorylation of histone 3 at serine 10, a marker of cellular transformation, was up-regulated in cells treated with NNK. This is the first study showing that NNK can alter gene expression that may, in part, account for transformation of HPV-immortalized human cervical cells. The results support previous epidemiological observations that, in addition to HPV, tobacco smoking also plays an important role in the development of cervical cancer.
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Affiliation(s)
- Bogdan Prokopczyk
- Department of Pharmacology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
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4
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Gaballah K, Costea DE, Hills A, Gollin SM, Harrison P, Partridge M. Tissue engineering of oral dysplasia. J Pathol 2008; 215:280-9. [DOI: 10.1002/path.2360] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Mo B, Pater A. Apoptosis, 5-fluorouracil sensitivity and expression of apoptotic proteins in a human ectocervical cell carcinogenesis model using different media. Eur J Pharmacol 2003; 467:15-22. [PMID: 12706450 DOI: 10.1016/s0014-2999(03)01561-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Apoptosis has received widespread attention for its essential roles in biology, medicine and cancer. We previously found that normal, human papillomavirus (HPV) 16-immortalized and their transformed endocervical cells were increasingly resistant to apoptosis induced by a cancer therapeutic drug. Here, analogously, another common anticancer drug, 5-fluorouracil, in an ectocervical cell carcinogenesis model induced apoptosis in primary human ectocervical cells (HEC), whereas HPV18-immortalized HEC (HEC-18) and transformed HEC-18 (HEC-18T) were more resistant. Growth in serum/low density lipoprotein (LDL)-containing medium reversed resistance to 5-fluorouracil-induced apoptosis, particularly in HEC-18T. Cell viability results confirmed these findings. Using Western blots to compare protein levels with those of HEC not treated with 5-fluorouracil, the fold changes in HEC-18 and HEC-18T in LDL-free medium were 1.6-6.1-fold lower for pro-apoptotic p53, Bak and Bax. Four anti-apoptotic proteins were altered -2.1 to+14.6-fold for Bcl-2 and BAG-1 isoform p33 and p29. For BAG-1 p50 and p46, HEC-18 were weakly expressed and HEC-18T were moderately higher. Grown in LDL-containing medium, the differences in pro-apoptotic protein levels were mostly reversed. Expression was 1.4-32-fold higher in HEC-18 and HEC-18T of p53, Bax, BAG-1 p29, BAG-1 p33 and total BAG-1. These results showed that HEC carcinogenesis results in resistance to 5-fluorouracil-induced apoptosis, associated with reduced expression during carcinogenesis of pro-apoptotic proteins and increased expression of specific anti-apoptotic proteins.
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Affiliation(s)
- Bilan Mo
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St. John's, Newfoundland, Canada A1B 3V6
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Ding Z, Green AG, Yang X, Chernenko G, Tang SC, Pater A. Retinoic acid inhibits telomerase activity and downregulates expression but does not affect splicing of hTERT: correlation with cell growth rate inhibition in an in vitro cervical carcinogenesis/multidrug-resistance model. Exp Cell Res 2002; 272:185-91. [PMID: 11777343 DOI: 10.1006/excr.2001.5412] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Telomerase, a ribonucleoprotein complex of hTERT, hTR, and TP1, has been reported to be associated with carcinogenesis and multidrug resistance (MDR). This study used our in vitro human cervical multistep carcinogenesis/MDR model system in which normal human ectocervical and endocervical (HEN) cells were immortalized by HPV18 or 16, respectively, and subsequently transformed. The first evidence was found that immortalization and telomerase activation were correlated with increased expression specifically of two of the hTERT alternatively spliced mRNAs, one encoding wild-type protein containing the full-length functional reverse transcriptase (RT) region and one encoding a defective RT protein. Expression of neither hTERT mRNA containing full-length functional or defective RT motif was affected by transformation/MDR. All-trans-retinoic acid (ATRA) treatment of HPV-immortalized HEN-16-2 cells and transformed/MDR HEN-16-2/CDDP cells inhibited telomerase activity and downregulated expression of hTERT mRNAs containing full-length functional and a defective RT motif, but there were no changes in hTR and TP1 expression. Moreover, ATRA inhibited cell growth rate of HEN-16-2 and HEN-16-2/CDDP cells equally. These results provided the first evidence that ATRA equally in both immortalized and transformed/MDR cell lines inhibits telomerase activity and downregulates expression, but not splicing, of hTERT, and this is correlated with cell growth rate inhibition; the potential is implicated for applying ATRA to hTERT-targeted treatment of cervical cell carcinogenesis/MDR.
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Affiliation(s)
- Zhihu Ding
- Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Canada
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7
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Retinoic Acid and Interferon-α Effects on Cell Growth and Differentiation in Cervical Carcinoma Cell Lines. Obstet Gynecol 2001. [DOI: 10.1097/00006250-200108000-00026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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8
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Tjiong MY, Out TA, Ter Schegget J, Burger MP, Van Der Vange N. Epidemiologic and mucosal immunologic aspects of HPV infection and HPV-related cervical neoplasia in the lower female genital tract: a review. Int J Gynecol Cancer 2001; 11:9-17. [PMID: 11285028 DOI: 10.1046/j.1525-1438.2001.011001009.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human papillomavirus (HPV) infections are known to play an important role in the pathogenesis of cervical neoplasia. Considering the morbidity and mortality of cervical cancer, infection with HPV can be regarded as a worldwide problem, especially in developing countries. Currently, many studies focus on the development of both prophylactic and therapeutic HPV vaccines. Crucial for these vaccination protocols to be successful is that they will result in a long-lasting ability to generate an immune response that will eliminate the virus. HPV transmission and subsequent infection is a local event in the lower female genital tract and therefore the efficacy of vaccines against this locally transmitted infection can be best assessed by parameters of local immunity. In this review we describe both the epidemiology of HPV-related cervical neoplasia and the general aspects of mucosal immunity in the female genital tract while focusing on the local humoral immunity in HPV-related cervical neoplasia.
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Affiliation(s)
- M Y Tjiong
- Department of Obstetrics and Gynecology, Academic Medical Center, Amsterdam, The Netherlands
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9
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Ding Z, Yang X, Chernenko G, Tang SC, Pater A. Human papillomavirus type 16-immortalized endocervical cells selected for resistance to cisplatin are malignantly transformed and have a multidrug resistance phenotype. Int J Cancer 2000; 87:818-23. [PMID: 10956392 DOI: 10.1002/1097-0215(20000915)87:6<818::aid-ijc10>3.0.co;2-m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cis-diamminedichloroplatinum (II) (cisplatin, CDDP) is a highly effective chemotherapeutic agent against cervical cancer, but drug resistance is a major obstacle in its clinical application. The mechanism of drug resistance in human cervical cancer is not well understood. Here, we established an in vitro endocervical, cisplatin-resistant cell system that mimics the development of cisplatin resistance in the human cervix. Human papillomavirus (HPV) type 16-immortalized human endocervical cells (HEN-16-2) were treated with cisplatin, and the cisplatin-selected cells (HEN-16-2/CDDP) were resistant to cisplatin, paclitaxel, actinomycin D, doxorubicin, etoposide, and 5-fluorouracil, thus demonstrating a multidrug resistance (MDR) phenotype. Furthermore, compared with a similar passage of drug-sensitive HEN-16-2 cells, HEN-16-2/CDDP cells exhibited the general growth characteristics of cancer cell lines: faster growth in medium containing serum and high calcium levels, higher saturation density, anchorage-independent growth, and formation of tumors in nude mice. These results provided the first in vitro evidence that cisplatin selection can transform HPV-immortalized endocervical cells and cause a phenotype of MDR.
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Affiliation(s)
- Z Ding
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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10
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Derchain SF, Roteli-Martins CM, Syrjänen KJ, de Abreu HJ, Martinez EZ, Alves VA. Association of oncogenic human papillomavirus DNA with high grade cervical intraepithelial neoplasia: the role of cigarette smoking. Sex Transm Infect 1999; 75:406-8. [PMID: 10754946 PMCID: PMC1758258 DOI: 10.1136/sti.75.6.406] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- S F Derchain
- Department of Gynecology, UNICAMP, Campinas, Brazil
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11
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Chen C, Nirunsuksiri W. Decreased expression of glutathione S-transferase M1 in HPV16-transfected human cervical keratinocytes in culture. Carcinogenesis 1999; 20:699-703. [PMID: 10223202 DOI: 10.1093/carcin/20.4.699] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glutathione S-transferase (GST) M1 is a member of the GST mu family of cytosolic enzymes that have been hypothesized to catalyze the conjugation of glutathione to a large number of hydrophobic substances, including carcinogens such as polynuclear aromatic hydrocarbons present in tobacco smoke, leading to their excretion. Epidemiologic and experimental evidence suggests that the risk of cervical cancer is related to both human papillomavirus (HPV) infection and cigarette smoking. We compared the enzymatic activities and mRNA levels of GSTs in GSTM1-positive human cervical keratinocytes (HCKs) that had been transfected with HPV16 with those in the parental cells. The GSTM1 activity toward the substrate trans-stilbene oxide was 5- to 7-fold lower than in the parental cells. The relative mRNA level in HCK transfected with HPV16 E6/E7, as quantified by reverse transcriptase-polymerase chain reaction (RT-PCR) with normalization against endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression, was 6% that of the parental cells. It was 16 and 82%, respectively, in cells that were transfected with HPV16 E6 alone or HPV16 E7 alone. When quantified by competitive RT-PCR using an exogenous nuclease-resistant synthetic cyclophilin RNA transcript as control, the mRNA level in HCK transfected with HPV16 E6 was approximately 10-fold lower that that in the parental cells. It was approximately 5- to 7-fold lower in the HPV16 E7 or HPV16 E6/E7 cells. Our results suggest that viral infections, through the modulation of cellular xenobiotic-metabolizing enzymes, may play a role in the ability of cells to handle environmental carcinogens.
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Affiliation(s)
- C Chen
- Program in Cancer Biology, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA.
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12
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Yang X, Nakao Y, Pater MM, Tang SC, Pater A. Expression of cellular genes in HPV16-immortalized and cigarette smoke condensate-transformed human endocervical cells. J Cell Biochem 1997. [DOI: 10.1002/(sici)1097-4644(19970901)66:3<309::aid-jcb4>3.0.co;2-t] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Zheng PS, Iwasaka T, Yokoyama M, Nakao Y, Pater A, Sugimori H. Telomerase activation in in vitro and in vivo cervical carcinogenesis. Gynecol Oncol 1997; 66:222-6. [PMID: 9264566 DOI: 10.1006/gyno.1997.4757] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Telomerase activity is found in the majority of human cancers, but not in most normal tissues. It is generally accepted that there is a multistep process in human carcinogenesis. Studying the role of telomerase activation in this process may provide new information to further our understanding of the pathological process of clinical lesions. In the present study, telomerase activity was found in HPV-immortalized and cigarette smoke condensate (CSC)-transformed malignant cell lines established in a cervical carcinogenesis model and in cell lines derived from cervical intraepithelial neoplasias (CINs) and carcinomas. With exfoliated cell samples, telomerase activity was detected in 3 of 41 (7%) normal cervices, 10 of 25 (40%) CINs, and all 20 (100%) carcinomas. Telomerase activation was significantly higher in CINs than in normal cervices (chi2 = 7.42, P < 0.01) and was much higher in invasive carcinomas than in CINs (chi2 = 18.00, P < 0.005). Our observations suggest that telomerase activation is a relatively early-stage event in cervical carcinogenesis, and this activation is associated with the initiation and progression of cervical lesions. Detection of telomerase activity may serve as a tool for diagnosis and prognosis of cervical neoplasias.
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Affiliation(s)
- P S Zheng
- Department of Obstetrics and Gynecology, Saga Medical School, Japan
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14
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Khare S, Pater MM, Tang SC, Pater A. Effect of glucocorticoid hormones on viral gene expression, growth, and dysplastic differentiation in HPV16-immortalized ectocervical cells. Exp Cell Res 1997; 232:353-60. [PMID: 9168812 DOI: 10.1006/excr.1997.3529] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Steroid hormones are proposed to act as cofactors with human papillomaviruses (HPVs) in the etiology of cervical cancer. We and others reported that progesterone and glucocorticoid hormones induce the expression of HPV16 via three glucocorticoid response elements (GREs) in the viral regulatory region. Consensus GREs (GREcs) are useful in other systems for examining the effect of hormones after enhancing the response with mutated GREc constructs. Therefore, this study used human ectocervical cells (HEC) and HPV type 16 containing three GREcs to establish immortalized cells (HEC-16GREc). Northern blot assays showed that the level of viral E6-E7 oncogene RNA was increased by hormones substantially more in HEC-16GREc than in wild-type HPV16-immortalized human ectocervical cells (HEC-16). The saturation density and the hormone response of the growth rate were significantly higher for HEC-16GREc and the doubling was faster in the presence of hormone than for HEC-16. Although both were nontumorigenic, only HEC-16GREc showed anchorage-independent growth, which was dependent on hormone. Also, HEC-16GREc were more abnormal in their epithelium differentiation pattern in organotypic (raft) cultures. Furthermore, hormone-treated HEC-16GREc rafts showed more dysplastic features than hormone-treated HEC-16 rafts. These results suggest new features of the role of hormones: that enhanced expression of viral oncogenes in response to hormones apparently confers a greater risk for cervical cells containing HPV16. Further, HEC-16GREc could be ideal for studying hormone-dependent and -independent malignant transformation.
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MESH Headings
- Animals
- Cell Culture Techniques/methods
- Cell Differentiation/drug effects
- Cell Division/drug effects
- Cell Line, Transformed
- Cell Transformation, Viral
- Cervix Uteri/cytology
- Consensus Sequence
- DNA, Viral/genetics
- Dexamethasone/pharmacology
- Epithelial Cells
- Female
- Gene Expression Regulation, Viral/drug effects
- Genome, Viral
- Humans
- Mice
- Mice, Nude
- Mutagenesis, Site-Directed
- Oncogene Proteins, Viral/biosynthesis
- Oncogene Proteins, Viral/genetics
- Oncogenes
- Papillomaviridae/genetics
- Papillomaviridae/physiology
- Papillomavirus E7 Proteins
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- Regulatory Sequences, Nucleic Acid
- Repressor Proteins
- Uterine Cervical Dysplasia/pathology
- Uterine Cervical Dysplasia/virology
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Affiliation(s)
- S Khare
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
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15
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Nakao Y, Yang X, Yokoyama M, Ferenczy A, Tang SC, Pater MM, Pater A. Induction of p16 during immortalization by HPV 16 and 18 and not during malignant transformation. Br J Cancer 1997; 75:1410-6. [PMID: 9166931 PMCID: PMC2223509 DOI: 10.1038/bjc.1997.243] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The p16 (MTS1) tumour-suppressor gene is a cyclin-dependent kinase (cdk) inhibitor that decelerates the cell cycle by inactivating the cdks that phosphorylate the retinoblastoma tumour-suppressor gene (Rb) protein (pRb). In cervical cancers, pRb is inactivated by the HPV E7 oncoprotein or by mutations. The hypothesis of earlier reports was that the disruption of the p16/cdk-cyclin/Rb cascade is essential for malignant cervical transformation/carcinogenesis. We previously established in vitro model systems of cervical cancer representing four steps of oncogenic progression initiated by the two most common oncogenic HPVs in ectocervical and endocervical epithelial cells. This report used these systems to investigate the role of p16 in cervical cancers. A dramatic enhancement of the p16 RNA level was observed after immortalization by HPV 16 or 18. Furthermore, the p16 protein was newly observed following immortalization. However, no further changes were found for RNA or protein levels after serum selection or malignant transformation. For three cervical carcinoma cell lines, similar high levels of p16 expression were seen. Point mutations or homozygous deletions of p16 were not observed in the in vitro systems or in clinical specimens. These results suggest that the inactivation of the p16/cdk-cyclin/Rb cascade does not occur during malignant transformation but occurs during the immortalization by HPV in HPV-harbouring premalignant lesions, the in situ equivalent of immortalized cells. Also suggested is that p16 has no role in the specific malignant transformation step from immortal premalignant lesions during the carcinogenesis of HPV-initiated cervical cancers.
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MESH Headings
- Adenocarcinoma/genetics
- Adenocarcinoma/metabolism
- Adenocarcinoma/virology
- Animals
- Carcinoma, Squamous Cell/genetics
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/virology
- Carrier Proteins/biosynthesis
- Carrier Proteins/genetics
- Cell Transformation, Neoplastic
- Cell Transformation, Viral
- Cyclin-Dependent Kinase Inhibitor p16
- DNA, Neoplasm/genetics
- DNA, Neoplasm/metabolism
- Female
- Gene Deletion
- Homozygote
- Humans
- Mice
- Mice, Nude
- Papillomaviridae
- Point Mutation
- Polymerase Chain Reaction
- Polymorphism, Single-Stranded Conformational
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Tumor Cells, Cultured
- Uterine Cervical Neoplasms/genetics
- Uterine Cervical Neoplasms/metabolism
- Uterine Cervical Neoplasms/virology
- Uterine Cervical Dysplasia/genetics
- Uterine Cervical Dysplasia/metabolism
- Uterine Cervical Dysplasia/virology
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Affiliation(s)
- Y Nakao
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada
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