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Hashemian Z, Afsharian P, Farzaneh P, Eftekhari-Yazdi P, Vakhshiteh F, Daneshvar Amoli A, Nasimian A. Establishment and characterization of a PCOS and a normal human granulosa cell line. Cytotechnology 2020; 72:10.1007/s10616-020-00426-3. [PMID: 32989584 PMCID: PMC7695766 DOI: 10.1007/s10616-020-00426-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 09/16/2020] [Accepted: 09/20/2020] [Indexed: 11/29/2022] Open
Abstract
Oocyte maturation is an important phase in fertility and any disorder in this process could lead to infertility. The most common disorder during folliculogenesis is polycystic ovary syndrome (PCOS). Due to the secretive activity of granulosa cells (GCs), they play a vital role in folliculogenesis. Although scientists use various cellular and molecular methods to have a better understanding of the mechanism of these cells, some limitations still exist in GC culture such as low primary cell yield and proliferation capability. Therefore, immortalization of primary cells is an approach to overcome these limitations. In the current study, GCs were obtained from two females, one with PCOS and one with normal folliculogenesis. In the first stage, we established two human GC (hGC) lines by immortalizing them through retrovirus-mediated transfer of the human telomerase reverse transcriptase (hTERT) and c-Myc genes. Subsequently, the normal and PCOS cell lines were characterized and were investigated for their growth features. The cell lines were also examined in terms of immortal markers of hTERT, follicle stimulating hormone receptor (FSHR), aromatase, anti-Müllerian hormone (AMH), growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15), estrogen, and progesterone. Our results indicated that the normal and PCOS cell lines both showed similar characteristics to GCs during the follicular stage in normal and PCOS women. The normal and PCOS cell lines demonstrate molecular mechanisms similar to that of GCs such as folliculogenesis, oogenesis, and steroidogenesis, which enable researchers to perform further investigations in future.
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Affiliation(s)
- Zohreh Hashemian
- Human and Animal Cell Bank, Iranian Biological Resource Center (IBRC), ACECR, Tehran, Iran
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Parvaneh Afsharian
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Parvaneh Farzaneh
- Human and Animal Cell Bank, Iranian Biological Resource Center (IBRC), ACECR, Tehran, Iran
| | - Poopak Eftekhari-Yazdi
- Department of Embryology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Faezeh Vakhshiteh
- Human and Animal Cell Bank, Iranian Biological Resource Center (IBRC), ACECR, Tehran, Iran
| | | | - Ahmad Nasimian
- Human and Animal Cell Bank, Iranian Biological Resource Center (IBRC), ACECR, Tehran, Iran.
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2
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The Fanconi anemia pathway controls oncogenic response in hematopoietic stem and progenitor cells by regulating PRMT5-mediated p53 arginine methylation. Oncotarget 2018; 7:60005-60020. [PMID: 27507053 PMCID: PMC5312365 DOI: 10.18632/oncotarget.11088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 07/26/2016] [Indexed: 01/26/2023] Open
Abstract
The Fanconi anemia (FA) pathway is involved in DNA damage and other cellular stress responses. We have investigated the role of the FA pathway in oncogenic stress response by employing an in vivo stress-response model expressing the Gadd45β-luciferase transgene. Using two inducible models of oncogenic activation (LSL-K-rasG12D and MycER), we show that hematopoietic stem and progenitor cells (HSPCs) from mice deficient for the FA core complex components Fanca or Fancc exhibit aberrant short-lived response to oncogenic insults. Mechanistic studies reveal that FA deficiency in HSPCs impairs oncogenic stress-induced G1 cell-cycle checkpoint, resulting from a compromised K-rasG12D-induced arginine methylation of p53 mediated by the protein arginine methyltransferase 5 (PRMT5). Furthermore, forced expression of PRMT5 in HSPCs from LSL-K-rasG12D/CreER-Fanca−/− mice prolongs oncogenic response and delays leukemia development in recipient mice. Our study defines an arginine methylation-dependent FA-p53 interplay that controls oncogenic stress response.
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Hosseinzadeh Anvar L, Hosseini-Asl S, Mohammadzadeh-Vardin M, Sagha M. The Telomerase Activity of Selenium-Induced Human Umbilical Cord Mesenchymal Stem Cells Is Associated with Different Levels of c-Myc and p53 Expression. DNA Cell Biol 2016; 36:34-41. [PMID: 27813686 DOI: 10.1089/dna.2016.3411] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Selenium-as a trace element-is nutritionally essential for humans. It prevents cancerous growth by inhibiting the telomerase activity but the mechanism involved in regulation of telomerase activity in normal telomerase-positive cells remains to be elucidated. Here, we find out whether the effect of sodium selenite and selenomethionine on telomerase activity in human umbilical cord-derived mesenchymal stem cells (hUCMSCs) is associated with different levels of c-Myc and p53 expression. The use of different staining methods including ethidium bromide/acridine orange and DAPI in addition to telomeric repeat amplification protocol assay and real-time PCR indicated that different forms of selenium have opposite impacts on c-Myc and p53 expressions in both hUCMSCs and AGS, a gastric adenocarcinoma cell line, as a positive control. Our findings suggest that the signaling pathways involved in the regulation of telomerase activity in malignant and normal telomerase-positive cell types are somewhat different, at least on the c-Myc and P53 expression levels.
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Affiliation(s)
- Leila Hosseinzadeh Anvar
- 1 Research Laboratory for Embryology and Stem Cells, Department of Anatomical Sciences and Pathology, Faculty of Medicine, Ardabil University of Medical Sciences , Ardabil, Iran .,2 Laboratory of Medical Genetics, Imam Khomeini Hospital, Ardabil University of Medical Sciences , Ardabil, Iran
| | - Saeid Hosseini-Asl
- 2 Laboratory of Medical Genetics, Imam Khomeini Hospital, Ardabil University of Medical Sciences , Ardabil, Iran
| | - Mohammad Mohammadzadeh-Vardin
- 1 Research Laboratory for Embryology and Stem Cells, Department of Anatomical Sciences and Pathology, Faculty of Medicine, Ardabil University of Medical Sciences , Ardabil, Iran
| | - Mohsen Sagha
- 1 Research Laboratory for Embryology and Stem Cells, Department of Anatomical Sciences and Pathology, Faculty of Medicine, Ardabil University of Medical Sciences , Ardabil, Iran
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Choi YH. Linoleic Acid-Induced Growth Inhibition of Human Gastric Epithelial Adenocarcinoma AGS Cells is Associated with Down-Regulation of Prostaglandin E2 Synthesis and Telomerase Activity. J Cancer Prev 2014; 19:31-8. [PMID: 25337570 PMCID: PMC4189473 DOI: 10.15430/jcp.2014.19.1.31] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 03/14/2014] [Accepted: 03/16/2014] [Indexed: 11/03/2022] Open
Affiliation(s)
- Yung Hyun Choi
- Correspondence to: Yung Hyun Choi, Department of Biochemistry, Dongeui University College of Oriental Medicine, San 45, Yangjung-dong, Busanjin-gu, Busan 614-052, Korea Tel: +82-51-850-7413, Fax: +82-51-853-4036, E-mail:
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5
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Wang C, Lisanti MP, Liao DJ. Reviewing once more the c-myc and Ras collaboration: converging at the cyclin D1-CDK4 complex and challenging basic concepts of cancer biology. Cell Cycle 2011; 10:57-67. [PMID: 21200143 DOI: 10.4161/cc.10.1.14449] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The c-myc is a proto-oncogene that manifests aberrant expression at high frequencies in most types of human cancer. C-myc gene amplifications are often observed in various cancers as well. Ample studies have also proved that c-myc has a potent oncogenicity, which can be further enhanced by collaborations with other oncogenes such as Bcl-2 and activated Ras. Studies on the collaborations of c-myc with Ras or other genes in oncogenicity have established several basic concepts and have disclosed their underlying mechanisms of tumor biology, including "immortalization" and "transformation". In many cases, these collaborations may converge at the cyclin D1-CDK4 complex. In the meantime, however, many results from studies on the c-myc, Ras and cyclin D1-CDK4 also challenge these basic concepts of tumor biology and suggest to us that the immortalized status of cells should be emphasized. Stricter criteria and definitions for a malignantly transformed status and a benign status of cells in culture also need to be established to facilitate our study of the mechanisms for tumor formation and to better link up in vitro data with animal results and eventually with human cancer pathology.
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Affiliation(s)
- Chenguang Wang
- Department of Stem Cell and Regenerative Medicine, and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
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Epigenetic plasticity of hTERT gene promoter determines retinoid capacity to repress telomerase in maturation-resistant acute promyelocytic leukemia cells. Leukemia 2010; 24:613-22. [PMID: 20072159 DOI: 10.1038/leu.2009.283] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The expression of hTERT gene, encoding the catalytic subunit of telomerase, is a feature of most cancer cells. Changes in the chromatin environment of its promoter and binding of transcriptional factors have been reported in differentiating cells when its transcription is repressed. However, it is not clear whether these changes are directly involved in this repression or only linked to differentiation. In a maturation-resistant acute promyelocytic leukemia (APL) cell line (NB4-LR1), we have previously identified a new pathway of retinoid-induced hTERT repression independent of differentiation. Using a variant of this cell line (NB4-LR1(SFD)), which resists to this repression, we show that although distinct patterns of histone modifications and transcription factor binding at the proximal domain of hTERT gene promoter could concur to modulate its expression, this region is not sufficient to the on/off switch of hTERT by retinoids. DNA methylation analysis of the hTERT promoter led to the identification of two distinct functional domains, a proximal one, fully unmethylated in both cell lines, and a distal one, significantly methylated in NB4-LR1(SFD) cells, whose methylation was further re-enforced by retinoid treatment. Interestingly, we showed that the binding to this distal domain of a known hTERT repressor, WT1, was defective only in NB4-LR1(SFD) cells. We propose that epigenetic modifications targeting this distal region could modulate the binding of hTERT repressors and account either for hTERT reactivation and resistance to retinoid-induced hTERT downregulation.
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Chang HS, Lin CH, Yang CH, Yen MS, Lai CR, Chen YR, Liang YJ, Yu WCY. Increased expression of Dyrk1a in HPV16 immortalized keratinocytes enable evasion of apoptosis. Int J Cancer 2007; 120:2377-85. [PMID: 17294446 DOI: 10.1002/ijc.22573] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Immortalization is a critical event in virus-related oncogenesis. No enough information, however, is currently available to elucidate the changes that occur in cellular molecules during immortalization. To identify potential cellular markers or regulators involving in immortalization, a paired-cell model of primary foreskin keratinocytes (FK) and HPV16 immortalized foreskin keratinocytes were established. Using mRNA differential display, RT-PCR and Northern blot methods, we have identified and confirmed that Dyrk1a (dual-specificity tyrosine-phosphorylated and regulated kinase 1A) is present and increased in HPV16 immortalized cells, but is absent in primary keratinocytes. Moreover, transfection of E7 siRNA oligo into immortalized cells leads to a diminishing E7 expression and the eventual disappearance of Dyrk1a. Similar results of Dyrk1a expressional differences could also be seen when tissue specimens were compared using LCM/real-time PCR and immunohistochemistry analysis; malignant cervical lesions contain significantly more DYRK1A than normal tissue. It was also demonstrated that raised DYRK1A could rearrange the cellular localization of FKHR (forkhead in rhabdomyosarcoma), an apoptosis activator, and suppress BAD. Importantly, this phenomenon can be reversed when endogenous Dyrk1a was knocked down in immortalized cells by RNA interference. These results suggest that the raised Dyrk1a in HPV16 immortalized keratinocytes and cervical lesions may serve as a candidate antiapoptotic factor in the FKHR regulated pathway and initiate immortalization and tumorigenesis gradually.
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Affiliation(s)
- Hung-Shu Chang
- Institute of Cancer Research, National Health Research Institutes, Miaoli County, Taiwan, Republic of China
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Park C, Kim GY, Kim WI, Hong SH, Park DI, Kim ND, Bae SJ, Jung JH, Choi YH. Induction of Apoptosis by (Z)-Stellettic Acid C, an Acetylenic Acid from the Sponge Stelletta sp., Is Associated with Inhibition of Telomerase Activity in Human Leukemic U937 Cells. Chemotherapy 2007; 53:160-8. [PMID: 17356266 DOI: 10.1159/000100809] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 06/13/2006] [Indexed: 01/04/2023]
Abstract
BACKGROUND (Z)-stellettic acid C, an acetylenic acid from the marine sponge Stelletta sp., has been shown to have cytotoxic activity in some cancer cells; however, its mechanisms on malignant cell growth are not known. In this study, the potential of (Z)-stellettic acid C to induce apoptosis in human leukemic U937 cells and its effects on telomerase activity were investigated. METHODS Cytotoxicity was evaluated by MTT assays. Apoptosis was detected using DAPI staining and annexin V fluorescein. The mRNAs of Bcl-2, inhibitor of apoptosis proteins (IAPs) family and Fas/FasL system were determined by RT-PCR. Caspases and telomerase activities were measured using colorimetric assay and telomeric repeat amplification protocol enzyme-linked immunosorbent assay (TRAP-ELISA), respectively. RESULTS Exposure of U937 cells to (Z)-stellettic acid C resulted in growth inhibition and induction of apoptosis in a dose-dependent manner, which was associated with the modulation of Bcl-2 family expression, activation of caspases and downregulation of IAPs family members. (Z)-Stellettic acid C treatment markedly inhibited the activity of telomerase in a dose-dependent fashion. Additionally, the expression of human telomerase reverse transcriptase, a main determinant of the telomerase enzymatic activity, was progressively downregulated by (Z)-stellettic acid C treatment. CONCLUSIONS These results suggest that (Z)-stellettic acid C could have a possible cancer therapeutic potential.
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Affiliation(s)
- Cheol Park
- Department of Oriental Medicine, Dongeui University College of Oriental Medicine, Busan, Korea
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Morelli F, Peluso G, Petillo O, Giannattasio A, Filosa S, Motta CM, Tammaro S, Zatterale A, Calzone R, Budillon A, Cartenì M, de Maria S, Costanza MR, Nigro A, Petrazzuolo M, Buommino E, Rizzo M, Capasso G, Baiano S, Moscatiello F, Ravagnan G, Fuggetta MP, Tajana G, Stiuso P, Metafora BM, Metafora V, Metafora S. The immunomodulatory protein SV-IV protects serum-deprived cells against apoptosis but not against G0/G1 arrest: Possible implications for the survival of implanting embryo. J Cell Physiol 2007; 212:610-25. [PMID: 17458892 DOI: 10.1002/jcp.21058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Serum deprivation induced in human lymphoblastoid Raji cells oxidative stress-associated apoptotic death and G0/G1 cell cycle arrest. Addition into culture medium of the immunomodulatory protein Seminal vesicle protein 4 (SV-IV) protected these cells against apoptosis but not against cycle arrest. The antiapoptotic activity was related to: (1) decrease of endocellular reactive Oxygen species (ROS) (2) increase of mRNAs encoding anti-oxidant enzymes (catalase, G6PD) and antiapoptotic proteins (survivin, cox-1, Hsp70, c-Fos); (3) decrease of mRNAs encoding proapoptotic proteins (c-myc, Bax, caspase-3, Apaf-1). The biochemical changes underlaying these effects were probably induced by a protein tyrosine kinase (PTK) activity triggered by the binding of SV-IV to its putative plasma membrane receptors. The ineffectiveness of SV-IV to abrogate the cycle arrest was accounted for by its downregulating effects on D1,3/E G1-cyclins and CdK2/4 gene expression, ppRb/pRb ratio, and intracellular ROS concentration. In conclusion, these experiments: (1) prove that SV-IV acts as a cell survival factor; (2) suggest the involvement of a PTK in SV-IV signaling; (3) point to cell cycle-linked enzyme inhibition as responsible for cycle arrest; (4) provide a model to dissect the cycle arrest and apoptosis induced by serum withdrawal; (5) imply a possible role of SV-IV in the survival of hemiallogenic implanting embryos.
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MESH Headings
- Animals
- Antioxidants/metabolism
- Antioxidants/pharmacology
- Apoptosis/drug effects
- Apoptosis Regulatory Proteins/genetics
- Apoptosis Regulatory Proteins/metabolism
- Catalase/genetics
- Catalase/metabolism
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Culture Media, Serum-Free/metabolism
- Cyclin-Dependent Kinases/metabolism
- Cyclins/metabolism
- Cytotoxicity, Immunologic
- DNA Fragmentation
- Embryo Culture Techniques
- Embryo Implantation/drug effects
- Embryonic Development
- G1 Phase/drug effects
- Genomic Instability
- Glucosephosphate Dehydrogenase/genetics
- Glucosephosphate Dehydrogenase/metabolism
- Humans
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Leukocytes, Mononuclear/drug effects
- Leukocytes, Mononuclear/enzymology
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Mice
- Mice, Inbred BALB C
- Oxidative Stress
- Phosphorylation
- Protein-Tyrosine Kinases/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Reactive Oxygen Species/metabolism
- Resting Phase, Cell Cycle/drug effects
- Retinoblastoma Protein/metabolism
- Seminal Vesicle Secretory Proteins/metabolism
- Seminal Vesicle Secretory Proteins/pharmacology
- Serum/metabolism
- Signal Transduction
- Time Factors
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Affiliation(s)
- Francesco Morelli
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, CNR, Via P Castellino 111, Naples, Italy
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Freyer MW, Buscaglia R, Kaplan K, Cashman D, Hurley LH, Lewis EA. Biophysical studies of the c-MYC NHE III1 promoter: model quadruplex interactions with a cationic porphyrin. Biophys J 2006; 92:2007-15. [PMID: 17172304 PMCID: PMC1861781 DOI: 10.1529/biophysj.106.097246] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of the structural equilibrium of G-quadruplex-forming sequences located in the promoter regions of oncogenes by the binding of small molecules has shown potential as a new avenue for cancer chemotherapy. In this study, microcalorimetry (isothermal titration calorimetry and differential scanning calorimetry), electronic spectroscopy (ultraviolet-visible and circular dichroism), and molecular modeling were used to probe the complex interactions between a cationic porphryin mesotetra (N-methyl-4-pyridyl) porphine (TMPyP4) and the c-MYC PU 27-mer quadruplex. The stoichiometry at saturation is 4:1 mol of TMPyP4/c-MYC PU 27-mer G-quadruplex as determined by isothermal titration calorimetry, circular dichroism, and ultraviolet-visible spectroscopy. The four independent TMPyP4 binding sites fall into one of two modes. The two binding modes are different with respect to affinity, enthalpy change, and entropy change for formation of the 1:1 and 2:1, or 3:1 and 4:1 complexes. Binding of TMPyP4, at or near physiologic ionic strength ([K(+)] = 0.13 M), is described by a "two-independent-sites model." The two highest-affinity sites exhibit a K(1) of 1.6 x 10(7) M(-1) and the two lowest-affinity sites exhibit a K(2) of 4.2 x 10(5) M(-1). Dissection of the free-energy change into the enthalpy- and entropy-change contributions for the two modes is consistent with both "intercalative" and "exterior" binding mechanisms. An additional complexity is that there may be as many as six possible conformational quadruplex isomers based on the sequence. Differential scanning calorimetry experiments demonstrated two distinct melting events (T(m)1 = 74.7 degrees C and T(m)2 = 91.2 degrees C) resulting from a mixture of at least two conformers for the c-MYC PU 27-mer in solution.
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Affiliation(s)
- Matthew W Freyer
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona, USA
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Flores I, Evan G, Blasco MA. Genetic analysis of myc and telomerase interactions in vivo. Mol Cell Biol 2006; 26:6130-8. [PMID: 16880523 PMCID: PMC1592815 DOI: 10.1128/mcb.00543-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Myc is a transcription factor with pleiotropic effects on tumorigenesis which are likely to be mediated by its target genes. A known Myc transcriptional target is the catalytic subunit of telomerase, Tert. However, the contribution of Tert activation to Myc-induced tumorigenesis in vivo remains unknown. In this study, we addressed the role of telomerase in Myc-induced skin papillomatosis by using compound mice with a switchable Myc gene, Inv-MycERTAM mice, in combination with either telomerase deficiency (Terc-/-) or telomerase overexpression (K5-mTert) in the skin. We first demonstrated that Myc activates telomerase in the skin. With Inv-MycERTAM x Terc-/- mice, we further showed that this telomerase activation is partially required to elicit a full hyperplastic Myc-induced response. The presence of critically short telomeres in late-generation Inv-MycERTAM x Terc-/- mice further reduced the skin lesion induced by Myc. On the other hand, telomerase overexpression in the skin of K5-mTert mice augments Myc-induced hyperplasia in the absence of changes in telomere length, suggesting a direct role of telomerase in the Myc protumorigenic response. Taken together, these results highlight telomerase as a mediator of Myc-induced papillomatosis and suggest telomerase as a putative therapeutic target for Myc-dependent lesions.
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Affiliation(s)
- Ignacio Flores
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
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Nishimura A, Nakahara T, Ueno T, Sasaki K, Yoshida S, Kyo S, Howley PM, Sakai H. Requirement of E7 oncoprotein for viability of HeLa cells. Microbes Infect 2006; 8:984-93. [PMID: 16500131 DOI: 10.1016/j.micinf.2005.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 10/19/2005] [Accepted: 10/20/2005] [Indexed: 11/17/2022]
Abstract
Most human papillomavirus (HPV)-positive cervical cancers contain integrated copies of the viral genome in their chromosomes and express the viral oncoproteins E6 and E7. A virus-encoded transcription factor, E2, is known to repress E6/E7 expression in HPV-positive cancer cells, leading to growth inhibition, which indicates that E6/E7 is required for the survival of the cells. We found that the E2-mediated growth inhibition of HeLa cells, an HPV18-positive cancer cell line, was coupled with a reduction in telomerase activity, an effect which was rescued by the complementation of E7 expression, but not E6 expression, indicating that the cell viability and the telomerase activity in HeLa cells are maintained by an E7-associated function. Analysis of E7 mutants suggested that the binding to the pRB family of pocket proteins was involved in the ability of E7 to rescue the growth potential and telomerase activity inhibited by E2 expression. We also showed that the telomerase activity upregulated by E7 expression was determined by the hTERT promoter activity, and that c-Myc upregulation caused by pRB inactivation could account for the promoter activity. The activation of p53 and consequent accumulation of p21Cip1, which were triggered by the downregulation of E6, appeared not to be essential for the E2-mediated growth arrest.
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Affiliation(s)
- Akiko Nishimura
- Laboratory of Gene Analysis, Department of Viral Oncology, Institute for Virus Research, Kyoto University, Sakyo-Ku, Kyoto 606-8507, Japan
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13
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Telomerase activity in colorectal carcinoma and its correlation with expression of c-myc. Chin J Cancer Res 2005. [DOI: 10.1007/s11670-005-0019-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Xiao X, Sidorov IA, Gee J, Lempicki RA, Dimitrov DS. Retinoic acid-induced downmodulation of telomerase activity in human cancer cells. Exp Mol Pathol 2005; 79:108-17. [PMID: 16054129 DOI: 10.1016/j.yexmp.2005.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 06/01/2005] [Indexed: 10/25/2022]
Abstract
Most human cancers express telomerase but its activity is highly variable and regulated by complex mechanisms. Recently, several studies have suggested that retinoic acid (RA) downregulates telomerase activity and that this effect could be a major determinant of its therapeutic activity. To elucidate possible mechanisms of RA-mediated downmodulation of telomerase activity, we measured the kinetics of concentration changes of several transcription regulators by using standard biochemical techniques at low (10 muM) and high (100 muM) RA concentrations. We further evaluated the global impact of the RA treatment on gene expression profiles using microarray. It was found that the kinetics of c-Myc correlates most closely with the telomerase activity suggesting in agreement with previous studies that this protein is a major intermediate of the RA-induced downregulation of telomerase activity. Other telomerase regulators as Sp1 and Mad1 did not exhibit significant correlation. The dominant role of c-Myc in RA-induced telomerase downmodulation is confirmed by microarray data. Additionally, a number of proteins were found as possible correlates of telomerase activity by microarray analysis. These data suggest a complex interplay between c-Myc and other proteins that may be important determinants of the RA effects on telomerase activity in human cancer cells. The complex mechanism through which telomerase activity is controlled during differentiation and cancer transformation is also reflected.
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Affiliation(s)
- Xiaodong Xiao
- Protein Interactions Group, Laboratory of Experimental and Computational Biology, NCI-Frederick, NIH, Bldg. 469, Rm. 139, P.O. Box B, Miller Drive, Frederick, MD 21702-1201, USA.
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15
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Shats I, Milyavsky M, Tang X, Stambolsky P, Erez N, Brosh R, Kogan I, Braunstein I, Tzukerman M, Ginsberg D, Rotter V. p53-dependent down-regulation of telomerase is mediated by p21waf1. J Biol Chem 2004; 279:50976-85. [PMID: 15371422 DOI: 10.1074/jbc.m402502200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inactivation of p53 and activation of telomerase occur in the majority of human cancers, raising the possibility of a link between these two pathways. Overexpression of wild-type p53 down-regulates the enzymatic activity of telomerase in various cancer cell lines through transcriptional repression of its catalytic subunit, human telomerase reverse transcriptase (hTERT). In this study, we re-evaluated the role of p53 in telomerase regulation using isogenic cell lines expressing physiological levels of p53. We demonstrate that endogenous wild-type p53 was able to down-regulate telomerase activity, hTERT mRNA levels, and promoter activity; however, the ability to repress hTERT expression was found to be cell type-specific. The integrity of the DNA-binding core domain, the N-terminal transactivation domain, and the C-terminal oligomerization domains of p53 was essential for hTERT promoter repression, whereas the proline-rich domain and the extreme C terminus were not required. Southwestern and chromatin immunoprecipitation experiments demonstrated lack of p53 binding to the hTERT promoter, raising the possibility of an indirect repressive mechanism. The down-regulation of hTERT promoter activity was abolished by a dominant-negative E2F1 mutant. Mutational analysis identified a specific E2F site responsible for p53-mediated repression. Knockdown of the key p53 transcriptional target, p21, was sufficient to eliminate the p53-dependent repression of hTERT. Inactivation of the Rb family using either viral oncoproteins or RNA interference attenuated the repression. Inhibition of histone deacetylases also interfered with the repression of hTERT by p53. Therefore, our results suggest that repression of hTERT by endogenous p53 is mediated by p21 and E2F.
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Affiliation(s)
- Igor Shats
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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16
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Datta A, Nag A, Pan W, Hay N, Gartel AL, Colamonici O, Mori Y, Raychaudhuri P. Myc-ARF (alternate reading frame) interaction inhibits the functions of Myc. J Biol Chem 2004; 279:36698-707. [PMID: 15199070 DOI: 10.1074/jbc.m312305200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The tumor suppressor protein ARF (alternate reading frame) inhibits MDM2 to stabilize and activate the functions of p53. Here we provide evidence for an additional activity of ARF that attenuates cell cycle progression independently of p53 activation. We show that ARF interacts with c-Myc independently of MDM2 or p53. Consequently, ARF relocalizes c-Myc from the nucleoplasm to the nucleolus. Binding and relocalization by ARF correlate with an inhibition of the c-Myc-activated transcription in both p53-positive and -negative cells. Using inducible cell lines, we show that the wild type ARF, but not a mutant, inhibits expression of the c-Myc-induced genes before inhibiting S phase. Moreover, ARF inhibits Myc-induced progression into S phase in cells lacking p53 or expressing a defective p53, indicating that ARF inhibits the S phase stimulatory function of c-Myc independently of p53. Our results strongly suggest that cMyc is a bona fide target of ARF and that ARF attenuates c-Myc independently of the ARF-p53 axis.
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MESH Headings
- Alternative Splicing
- Animals
- Blotting, Northern
- Blotting, Western
- Bromodeoxyuridine/pharmacology
- Cell Line, Tumor
- Cells, Cultured
- Chloramphenicol O-Acetyltransferase/metabolism
- Coloring Agents/pharmacology
- Cyclin-Dependent Kinase Inhibitor p16
- Epitopes
- Fibroblasts/metabolism
- G1 Phase
- Genes, Reporter
- HeLa Cells
- Humans
- Mice
- Microscopy, Confocal
- Microscopy, Fluorescence
- Models, Biological
- Mutation
- Nuclear Proteins/metabolism
- Plasmids/metabolism
- Precipitin Tests
- Protein Binding
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-mdm2
- Proto-Oncogene Proteins c-myc/antagonists & inhibitors
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Small Interfering/metabolism
- Reading Frames
- S Phase
- Tetracycline/pharmacology
- Transcription, Genetic
- Transfection
- Transgenes
- Tumor Suppressor Protein p14ARF/metabolism
- Tumor Suppressor Protein p14ARF/physiology
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- Abhishek Datta
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 S. Ashland Avenue, Chicago, IL 60607, USA
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17
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Teng SC, Chen YY, Su YN, Chou PC, Chiang YC, Tseng SF, Wu KJ. Direct Activation of HSP90A Transcription by c-Myc Contributes to c-Myc-induced Transformation. J Biol Chem 2004; 279:14649-55. [PMID: 14724288 DOI: 10.1074/jbc.m308842200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The c-myc proto-oncogene encodes a ubiquitous transcription factor involved in the control of cell growth and differentiation and implicated in inducing tumorigenesis. Understanding the function of c-Myc and its role in cancer depends upon the identification of c-Myc target genes. Heat shock protein 90 (HSP90) is involved in the folding of proteins such as signal transduction molecules (Src, Raf1, cdk4) and steroid receptors and in enhancing the activity of telomerase and nitric-oxide synthase. Here we show that c-Myc directly activates HSP90A transcription. c-Myc-mediated induction of HSP90A transcription occurs in different tissues, is independent of cell proliferation, and is mediated by a c-Myc binding site in the proximal promoter region of HSP90A gene. Overexpression of HSP90A in Rat1a cells induces transformation. Short interference RNA of HSP90A/Hsp86alpha reduces transformation activity in HeLa and RatMyc cells. These results indicate that by induction of HSP90A c-Myc may control the activity of multiple signal pathways involved in cellular transformation.
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MESH Headings
- Agar/metabolism
- Animals
- Binding Sites
- Blotting, Northern
- Blotting, Western
- Cell Division
- Cell Line
- Cell Line, Tumor
- Cell Transformation, Neoplastic
- Chromatin/metabolism
- Cloning, Molecular
- Genes, Reporter
- HSP90 Heat-Shock Proteins/metabolism
- HeLa Cells
- Humans
- Luciferases/metabolism
- Mice
- Mice, Nude
- NIH 3T3 Cells
- Plasmids/metabolism
- Precipitin Tests
- Promoter Regions, Genetic
- Proto-Oncogene Mas
- Proto-Oncogene Proteins c-myc/metabolism
- RNA, Small Interfering/metabolism
- Rats
- Signal Transduction
- Transcription, Genetic
- Transfection
- U937 Cells
- Up-Regulation
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Affiliation(s)
- Shu-Chun Teng
- Institute of Biochemistry, National Yang-Ming University, Taipei 112, Taiwan
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18
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Liu SX, Sun WS, Cao YL, Ma CH, Han LH, Zhang LN, Wang ZG, Zhu FL. Antisense oligonucleotide targeting at the initiator of hTERT arrests growth of hepatoma cells. World J Gastroenterol 2004; 10:366-70. [PMID: 14760759 PMCID: PMC4724927 DOI: 10.3748/wjg.v10.i3.366] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To evaluate the inhibitory effect of antisense phosphorothioate oligonucleotide (asON) complementary to the initiator of human telomerase catalytic subunit (hTERT) on the growth of hepatoma cells.
METHODS: The as-hTERT was synthesized by using a DNA synthesizer. HepG2.2.15 cells were treated with as-hTERT at the concentration of 10 μmol/L. After 72 h, these cells were obtained for detecting growth inhibition, telomerase activity using the methods of MTT, TRAP-PCR-ELISA, respectively. BALB/c(nu/nu) mice were injected HepG2.2.15 cells and a human-nude mice model was obtained. There were three groups for anti-tumor activity study. Once tumors were established, these animals in the first group were administered as-hTERT and saline. Apoptosis of tumor cells was detected by FCM. In the 2nd group, the animals were injected HepG2.2.15 cells together with as-hTERT. In the third group, the animals were given as-hTERT 24 hours postinjection of HepG2.2.15 cells. The anti-HBV effects were assayed with ELISA in vitro and in vivo.
RESULTS: Growth inhibition was observed in cells treated with as-hTERT in vitro. A significant different in the value of A570 - A630 was found between cells treated with as-hTERT and control (P < 0.01) by MTT method. The telomerase activity of tumor cells treated with as-hTERT was reduced, the value of A450 nm was 0.42 compared to control (1.49) with TRAP-PCR-ELISA. The peak of apoptosis in tumor cells given as-hTERT was 21.12%, but not seen in saline-treated control. A prolonged period of carcinogenesis was observed in the second and third group animals. There was inhibitory effect on the expression of HBsAg and HBeAg in vivo and in vitro.
CONCLUSION: As-hTERT has an anti-tumor activity, which may be useful for gene therapy of tumors.
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Affiliation(s)
- Su-Xia Liu
- Institute of Immunology, Medical School of Shandong University, Wenhua West Road 44, Jinan 250012, Shandong Province, China
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19
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Goueli BS, Janknecht R. Upregulation of the Catalytic Telomerase Subunit by the Transcription Factor ER81 and Oncogenic HER2/Neu, Ras, or Raf. Mol Cell Biol 2004; 24:25-35. [PMID: 14673140 PMCID: PMC303367 DOI: 10.1128/mcb.24.1.25-35.2004] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Accepted: 09/28/2003] [Indexed: 01/10/2023] Open
Abstract
One hallmark of tumor formation is the transcriptional upregulation of human telomerase reverse transcriptase, hTERT, and the resultant induction of telomerase activity. However, little is presently understood about how hTERT is differentially activated in tumor cells versus normal somatic cells. Specifically, it is unclear if oncoproteins can directly elicit hTERT expression. To this end, we now show that three oncoproteins, HER2/Neu, Ras, and Raf, stimulate hTERT promoter activity via the ETS transcription factor ER81 and ERK mitogen-activated protein (MAP) kinases. Mutating ER81 binding sites in the hTERT promoter or suppression of ERK MAP kinase-dependent phosphorylation of ER81 rendered the hTERT promoter unresponsive to HER2/Neu. Further, expression of dominant-negative ER81 or inhibition of HER2/Neu significantly attenuated telomerase activity in HER2/Neu-overexpressing SKBR3 breast cancer cells. Moreover, HER2/Neu, Ras, and Raf collaborated with ER81 to enhance endogenous hTERT gene transcription and telomerase activity in hTERT-negative, nonimmortalized BJ foreskin fibroblasts. Accordingly, hTERT expression was increased in HER2/Neu-positive breast tumors and breast tumor cell lines relative to their HER2/Neu-negative counterparts. Collectively, our data elucidated a mechanism whereby three prominent oncoproteins, HER2/Neu, Ras, and Raf, may facilitate tumor formation by inducing hTERT expression in nonimmortalized cells via the transcription factor ER81.
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Affiliation(s)
- Basem S Goueli
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
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20
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Xiao X, Athanasiou M, Sidorov IA, Horikawa I, Cremona G, Blair D, Barret JC, Dimitrov DS. Role of Ets/Id proteins for telomerase regulation in human cancer cells. Exp Mol Pathol 2003; 75:238-47. [PMID: 14611815 DOI: 10.1016/s0014-4800(03)00092-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most human cancers express telomerase but its activity is highly variable and regulated by complex mechanisms. Recently, we have proposed that Ets proteins may be important for regulation of telomerase activity in leukemic cells. Here we provide further evidence for the role of Ets family members and related Id proteins in telomerase regulation and characterize the underlying molecular mechanisms. By using PCR-based and gel shift assays we demonstrated specific binding to a core hTERT promoter of Ets2, Fli1, Id2, c-Myc, Mad1, and Sp1 in lysates from subclones of U937 cells. Further analysis of binding of purified proteins and various mutants of the hTERT promoter suggested the existence of a trimolecular Ets-Id2-DNA complex, and Ets inhibitory activity mediated by c-Myc and the Ets binding site on the core hTERT promoter at -293 bp from the transcription initiation site as well as a positive Ets regulatory effect mediate through another Ets binding site at -36 bp. This analysis provided evidence for the existence of negative and positive Ets regulatory site and suggested a complex interplay between Ets/Id family members and c-Myc that may be an important determinant of the diversity of telomerase activity in leukemia and other cancers.
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Affiliation(s)
- Xiaodong Xiao
- Laboratory of Experimental and Computational Biology, NCI-Frederick, NIH, Miller Drive, Frederick, MD 21702-1201, USA.
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21
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Goueli BS, Janknecht R. Regulation of telomerase reverse transcriptase gene activity by upstream stimulatory factor. Oncogene 2003; 22:8042-7. [PMID: 12970752 DOI: 10.1038/sj.onc.1206847] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Upregulation of human telomerase reverse transcriptase (hTERT) transcription accounts for the immortalization of greater than 85% of all human tumor cells. However, the mechanism whereby hTERT expression is activated remains unresolved. Specifically, recent data challenging the role of Myc/Max in E-box-dependent activation of hTERT expression suggests that other E-box-binding proteins regulate hTERT transcription. Indeed, we now demonstrate that two such proteins, upstream stimulatory factor (USF) 1 and 2, readily associate with two E-boxes in the hTERT promoter in vitro and in vivo primarily as heterodimers, whereas Myc/Max does not. The avid binding of USF1/2 heterodimers to these E-boxes occurs in both hTERT-positive and -negative cells. In contrast, USF1/2 activates the hTERT promoter exclusively in hTERT-positive cells in a manner that is enhanced by the coactivator p300 and attenuated upon inhibiting p38-MAP kinase, a known modulator of USF activity. Collectively, our data indicate that USF binding to the hTERT promoter may be transcriptionally neutral, or even repressive, in nonimmortalized hTERT-negative somatic cells, but stimulatory in hTERT-positive cells where USF1/2 contributes to the acquisition and maintenance of immortality.
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Affiliation(s)
- Basem S Goueli
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
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22
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Horikawa I, Cable PL, Mazur SJ, Appella E, Afshari CA, Barrett JC. Downstream E-box-mediated regulation of the human telomerase reverse transcriptase (hTERT) gene transcription: evidence for an endogenous mechanism of transcriptional repression. Mol Biol Cell 2002; 13:2585-97. [PMID: 12181331 PMCID: PMC117927 DOI: 10.1091/mbc.e01-11-0107] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2001] [Revised: 04/01/2002] [Accepted: 05/01/2002] [Indexed: 01/02/2023] Open
Abstract
Regulation of the hTERT gene encoding the telomerase catalytic subunit plays an important role in human cell senescence, immortalization, and carcinogenesis. By examining the activity of various deleted or mutated hTERT promoter fragments, we show that an E-box element downstream of the transcription initiation site is critical to differential hTERT transcription between the telomerase/hTERT-positive renal cell carcinoma cell line (RCC23) and its telomerase/hTERT-negative counterpart containing a transferred, normal chromosome 3 (RCC23+3). This E-box element mediated repression of hTERT transcription in RCC23+3 but not in RCC23. A copy number-dependent enhancement of the repression suggested active repression, rather than loss of activation, in RCC23+3. Endogenous expression levels of c-Myc or Mad1, which could activate or repress hTERT transcription when overexpressed, did not account for the differential hTERT transcription. Gel mobility shift assays identified the upstream stimulatory factors (USFs) as a major E-box-binding protein complex in both RCC23 and RCC23+3 and, importantly, detected an RCC23+3-specific, E-box-binding factor that was distinct from the USF and Myc/Mad families. The E-box-mediated repression was also active in normal human fibroblasts and epithelial cells and inactive in some, but not all, telomerase/hTERT-positive cancer cells. These findings provide evidence for an endogenous, repressive mechanism that actively functions in telomerase/hTERT-negative normal cells and becomes defective during carcinogenic processes, e.g., by an inactivation of the telomerase repressor gene on chromosome 3.
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Affiliation(s)
- Izumi Horikawa
- Laboratory of Biosystems and Cancer, Cancer and Aging Section, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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23
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Giridharan P, Somasundaram ST, Perumal K, Vishwakarma RA, Karthikeyan NP, Velmurugan R, Balakrishnan A. Novel substituted methylenedioxy lignan suppresses proliferation of cancer cells by inhibiting telomerase and activation of c-myc and caspases leading to apoptosis. Br J Cancer 2002; 87:98-105. [PMID: 12085264 PMCID: PMC2364294 DOI: 10.1038/sj.bjc.6600422] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2001] [Revised: 04/04/2002] [Accepted: 05/25/2002] [Indexed: 12/14/2022] Open
Abstract
Conventional solvent fractionation and bioactivity based target assays were used to identify a new anti-cancer molecule from Phyllanthus urinaria, a herbal medicinal plant used in South India. At each step of the purification process the different fractions that were isolated were tested for specific anti-proliferative activity by assays measuring the inhibition of [(3)H]thymidine incorporation, and trypan blue drug exclusion. The ethyl acetate fraction that contained the bioactivity was further purified and resolved by HPLC on a preparative column. The purity of each of the fractions and their bioactivity were checked. Fraction 3 demonstrated a single spot on TLC and showed maximum anti-proliferative activity. This fraction was further purified and the structure was defined as 7'-hydroxy-3',4',5,9,9'-pentamethoxy-3,4-methylene dioxy lignan using NMR and mass spectrometry analysis. The pure compound and the crude ethyl acetate fraction which showed anti-proliferative activities were examined for ability to target specific markers of apoptosis like bcl2, c-myc and caspases and for effects on telomerase. Four specific cancer cell lines HEp2, EL-1 monocytes, HeLa and MCP7 were used in this study. The results indicate that 7'-hydroxy-3',4',5,9,9'-pentamethoxy-3,4-methylene dioxy lignan was capable of inhibiting telomerase activity and also could inhibit bcl2 and activate caspase 3 and caspase 8 whose significance in the induction of apoptosis is well known. We believe that this compound could serve as a valuable chemotherapeutic drug after further evaluations.
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Affiliation(s)
- P Giridharan
- Centre for Biotechnology, Anna University, Chennai 600 025, India
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24
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Medina D, Kittrell FS, Shepard A, Stephens LC, Jiang C, Lu J, Allred DC, McCarthy M, Ullrich RL. Biological and genetic properties of the p53 null preneoplastic mammary epithelium. FASEB J 2002; 16:881-3. [PMID: 11967232 DOI: 10.1096/fj.01-0885fje] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The absence of the tumor suppressor gene p53 confers an increased tumorigenic risk for mammary epithelial cells. In this report, we describe the biological and genetic properties of the p53 null preneoplastic mouse mammary epithelium in a p53 wild-type environment. Mammary epithelium from p53 null mice was transplanted serially into the cleared mammary fat pads of p53 wild-type BALB/c female to develop stable outgrowth lines. The outgrowth lines were transplanted for 10 generations. The outgrowths were ductal in morphology and progressed through ductal hyperplasia and ductal carcinoma in situ before invasive cancer. The preneoplastic outgrowth lines were immortal and exhibited activated telomerase activity. They are estrogen and progesterone receptor-positive, and aneuploid, and had various levels of tumorigenic potential. The biological and genetic properties of these lines are distinct from those found in most hyperplastic alveolar outgrowth lines, the form of mammary preneoplasia occurring in most traditional models of murine mammary tumorigenesis. These results indicate that the preneoplastic cell populations found in this genetically engineered model are similar in biological properties to a subset of precurser lesions found in human breast cancer and provide a unique model to identify secondary events critical for tumorigenicity and invasiveness.
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MESH Headings
- Aneuploidy
- Animals
- Carcinoma in Situ/genetics
- Carcinoma in Situ/metabolism
- Carcinoma in Situ/pathology
- Carcinoma, Intraductal, Noninfiltrating/genetics
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Carcinoma, Intraductal, Noninfiltrating/pathology
- Epithelium/metabolism
- Epithelium/pathology
- Genotype
- Hyperplasia
- In Vitro Techniques
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/pathology
- Mammary Neoplasms, Animal/genetics
- Mammary Neoplasms, Animal/metabolism
- Mammary Neoplasms, Animal/pathology
- Mice
- Mice, Knockout
- Precancerous Conditions/genetics
- Precancerous Conditions/metabolism
- Precancerous Conditions/pathology
- Receptors, Estrogen/metabolism
- Tumor Suppressor Protein p53/genetics
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Affiliation(s)
- Daniel Medina
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
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25
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Mergny JL, Riou JF, Mailliet P, Teulade-Fichou MP, Gilson E. Natural and pharmacological regulation of telomerase. Nucleic Acids Res 2002; 30:839-65. [PMID: 11842096 PMCID: PMC100331 DOI: 10.1093/nar/30.4.839] [Citation(s) in RCA: 273] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2001] [Revised: 11/29/2001] [Accepted: 11/29/2001] [Indexed: 01/14/2023] Open
Abstract
The extremities of eukaryotic chromosomes are called telomeres. They have a structure unlike the bulk of the chromosome, which allows the cell DNA repair machinery to distinguish them from 'broken' DNA ends. But these specialised structures present a problem when it comes to replicating the DNA. Indeed, telomeric DNA progressively erodes with each round of cell division in cells that do not express telomerase, a specialised reverse transcriptase necessary to fully duplicate the telomeric DNA. Telomerase is expressed in tumour cells but not in most somatic cells and thus telomeres and telomerase may be proposed as attractive targets for the discovery of new anticancer agents.
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Affiliation(s)
- Jean-Louis Mergny
- Laboratoire de Biophysique, Muséum National d'Histoire Naturelle, INSERM U 201, CNRS UMR 8646, 43 rue Cuvier, F-75005 Paris, France.
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