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Babion I, Jaspers A, van Splunter AP, van der Hoorn IA, Wilting SM, Steenbergen RD. miR-9-5p Exerts a Dual Role in Cervical Cancer and Targets Transcription Factor TWIST1. Cells 2019; 9:E65. [PMID: 31888045 PMCID: PMC7017350 DOI: 10.3390/cells9010065] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/19/2019] [Accepted: 12/24/2019] [Indexed: 12/19/2022] Open
Abstract
Squamous cell carcinoma (SCC) and adenocarcinoma (AC) represent the major cervical cancer histotypes. Both histotypes are caused by infection with high-risk HPV (hrHPV) and are associated with deregulated microRNA expression. Histotype-dependent expression has been observed for miR-9-5p, showing increased expression in SCC and low expression in AC. Here, we studied the regulation and functionality of miR-9-5p in cervical SCCs and ACs using cervical tissue samples and hrHPV-containing cell lines. Expression and methylation analysis of cervical tissues revealed that low levels of miR-9-5p in ACs are linked to methylation of its precursor genes, particularly miR-9-1. Stratification of tissue samples and hrHPV-containing cell lines suggested that miR-9-5p depends on both histotype and hrHPV type, with higher expression in SCCs and HPV16-positive cells. MiR-9-5p promoted cell viability and anchorage independence in cervical cancer cell lines SiHa (SCC, HPV16) and CaSki (metastasized SCC, HPV16), while it played a tumor suppressive role in HeLa (AC, HPV18). TWIST1, a transcription factor involved in epithelial-to-mesenchymal transition (EMT), was established as a novel miR-9-5p target. Our results show that miR-9-5p plays a dual role in cervical cancer in a histotype- and hrHPV type-dependent manner. MiR-9-5p mediated silencing of TWIST1 suggests two distinct mechanisms towards EMT in cervical cancer.
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Affiliation(s)
- Iris Babion
- Cancer Center Amsterdam, Pathology, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Annelieke Jaspers
- Cancer Center Amsterdam, Pathology, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Annina P. van Splunter
- Cancer Center Amsterdam, Pathology, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Iris A.E. van der Hoorn
- Cancer Center Amsterdam, Pathology, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Saskia M. Wilting
- Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Renske D.M. Steenbergen
- Cancer Center Amsterdam, Pathology, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
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Wilting SM, Miok V, Jaspers A, Boon D, Sørgård H, Lando M, Snoek BC, van Wieringen WN, Meijer CJLM, Lyng H, Snijders PJF, Steenbergen RDM. Aberrant methylation-mediated silencing of microRNAs contributes to HPV-induced anchorage independence. Oncotarget 2018; 7:43805-43819. [PMID: 27270309 PMCID: PMC5190061 DOI: 10.18632/oncotarget.9698] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/13/2016] [Indexed: 12/17/2022] Open
Abstract
Cervical cancer and a subset of anogenital and head-and-neck carcinomas are caused by high-risk types of the human papillomavirus (hrHPV). During hrHPV-induced malignant transformation keratinocytes become able to grow anchorage independently, a tumorigenic trait at least partly associated with inactivation of tumor suppressor genes. We used hrHPV-containing keratinocytes to investigate the role of DNA methylation-mediated silencing of microRNAs (miRNAs) in the acquisition of anchorage independence. Anchorage dependent (n=11) and independent passages (n=19) of 4 hrHPV-immortalized keratinocyte cell lines were treated with 2′-deoxy-5-azacytidine (DAC). Genome-wide miRNA expression profiles before and after treatment were compared to identify miRNAs silenced by methylation. Bisulfite sequencing and methylation-specific PCR showed increased methylation of hsa-mir-129-2/-137/-935/-3663/-3665 and -4281 in anchorage independent HPV-transformed keratinocytes and cervical cancer cell lines. Mature miRNAs derived from hsa-mir-129-2/-137/-3663 and -3665 showed functional relevance as they decreased anchorage independence in cervical cancer cell lines. Cervical (pre)cancerous lesions demonstrated increased methylation of hsa-mir-129-2/-935/-3663/-3665 and -4281, underlining the clinical relevance of our findings. In conclusion, methylation-mediated silencing of tumor suppressive miRNAs contributes to acquisition of an anchorage independent phenotype. This study further substantiates the importance of miRNAs during early stages of carcinogenesis and underlines their potential as both disease markers and therapeutic targets.
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Affiliation(s)
- Saskia M Wilting
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Viktorian Miok
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.,Department of Epidemiology & Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
| | - Annelieke Jaspers
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Debby Boon
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Hanne Sørgård
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Malin Lando
- Department of Radiation Biology, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Barbara C Snoek
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Wessel N van Wieringen
- Department of Epidemiology & Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
| | - Chris J L M Meijer
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Heidi Lyng
- Department of Radiation Biology, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Peter J F Snijders
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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Ribero S, Mangino M, Bataille V. Skin phenotypes can offer some insight about the association between telomere length and cancer susceptibility. Med Hypotheses 2016; 97:7-10. [PMID: 27876133 DOI: 10.1016/j.mehy.2016.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/03/2016] [Accepted: 10/18/2016] [Indexed: 11/26/2022]
Abstract
The role of telomere biology in cancer has been studied for a wide variety of different cancers but the association with telomere length has been controversial. This is because some cancers have been found to be associated with longer telomeres in circulating white cells whilst other cancer types are more common in individuals with shorter telomeres. Hence, there has been some skepticism as to whether telomere length may be helpful in estimating cancer risk. For melanoma, however, results have been fairly consistent showing that longer telomeres are associated with an increased risk. This link was first discovered because of a link between longer telomeres and a high number of naevi. In contrast, for cutaneous squamous cell carcinomas, the relationship is reversed with higher risk in individuals with shorter telomeres. Differences in skin phenotypes with the presence of high number of naevi versus photoageing with solar elastosis and solar keratoses have already been valuable for dermatologists as the former phenotype is associated with melanoma whilst the latter is more common in patients with squamous cell carcinoma of the skin. The hypothesis is that the differences in cutaneous phenotypes already observed by dermatologists for skin cancers may, in fact, be useful as well for cancer prediction in general as it may reflect underlying telomere biology. This manuscript will address the evidence for links between telomere biology, skin phenotypes and cancer risk.
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Affiliation(s)
- S Ribero
- Department of Twin Research and Genetic Epidemiology, King's College London, UK; Department of Medical Sciences, University of Turin, Turin, Italy.
| | - M Mangino
- Department of Twin Research and Genetic Epidemiology, King's College London, UK
| | - V Bataille
- Department of Twin Research and Genetic Epidemiology, King's College London, UK; Department of Dermatology, West Herts NHS Trust, Herts, UK
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4
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Studies of Tumor Suppressor Genes via Chromosome Engineering. Cancers (Basel) 2015; 8:cancers8010004. [PMID: 26729168 PMCID: PMC4728451 DOI: 10.3390/cancers8010004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 12/01/2022] Open
Abstract
The development and progression of malignant tumors likely result from consecutive accumulation of genetic alterations, including dysfunctional tumor suppressor genes. However, the signaling mechanisms that underlie the development of tumors have not yet been completely elucidated. Discovery of novel tumor-related genes plays a crucial role in our understanding of the development and progression of malignant tumors. Chromosome engineering technology based on microcell-mediated chromosome transfer (MMCT) is an effective approach for identification of tumor suppressor genes. The studies have revealed at least five tumor suppression effects. The discovery of novel tumor suppressor genes provide greater understanding of the complex signaling pathways that underlie the development and progression of malignant tumors. These advances are being exploited to develop targeted drugs and new biological therapies for cancer.
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Schütze DM, Kooter JM, Wilting SM, Meijer CJLM, Quint W, Snijders PJF, Steenbergen RDM. Longitudinal assessment of DNA methylation changes during HPVE6E7-induced immortalization of primary keratinocytes. Epigenetics 2015; 10:73-81. [PMID: 25580631 DOI: 10.4161/15592294.2014.990787] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
High-risk human papillomavirus (hrHPV)-induced immortalization and malignant transformation are accompanied by DNA methylation of host genes. To determine when methylation is established during cell immortalization and whether it is hrHPV-type dependent, DNA methylation was studied in a large panel of HPVE6E7-immortalized keratinocyte cell lines. These cell lines displayed different growth behaviors, i.e., continuous growth versus crisis period prior to immortalization, reflecting differential immortalization capacities of the 7 HPV-types (16/18/31/33/45/66/70) studied. In this study, cells were monitored for hypermethylation of 14 host genes (APC, CADM1, CYGB, FAM19A4, hTERT, mir124-1, mir124-2, mir124-3, MAL, PHACTR3, PRDM14, RASSF1A, ROBO3, and SFRP2) at 4 different stages during immortalization. A significant increase in overall methylation levels was seen with progression through each stage of immortalization. At stage 1 (pre-immortalization), a significant increase in methylation of hTERT, mir124-2, and PRDM14 was already apparent, which continued over time. Methylation of ROBO3 was significantly increased at stage 2 (early immortal), followed by CYGB (stage 3) and FAM19A4, MAL, PHACTR3, and SFRP2 (stage 4). Methylation patterns were mostly growth behavior independent. Yet, hTERT methylation levels were significantly increased in cells that just escaped from crisis. Bisulfite sequencing of hTERT confirmed increased methylation in immortal cells compared to controls, with the transcription core and known repressor sites remaining largely unmethylated. In conclusion, HPV-induced immortalization is associated with a sequential and progressive increase in promoter methylation of a subset of genes, which is mostly independent of the viral immortalization capacity.
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Affiliation(s)
- Denise M Schütze
- a Department of Pathology; Unit of Molecular Pathology ; VU University Medical Center ; Amsterdam , The Netherlands
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Differential in vitro immortalization capacity of eleven (probable) [corrected] high-risk human papillomavirus types. J Virol 2013; 88:1714-24. [PMID: 24257607 DOI: 10.1128/jvi.02859-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Epidemiological studies identified 12 high-risk HPV (hrHPV) types and 8 probable/possible hrHPV types that display different cancer risks. Functional studies on transforming properties of hrHPV are mainly limited to HPV16 and -18, which induce immortalization of human foreskin keratinocytes (HFKs) by successive bypass of two proliferative life span barriers, senescence and crisis. Here, we systematically compared the in vitro immortalization capacities, as well as influences on p53, pRb, hTERT, growth behavior, and differentiation capacity, of nine hrHPV types (HPV16, -18, -31, -33, -35, -45, -51, -52, and -59), and two probable hrHPV types (HPV66 and -70). By retroviral transduction, the respective E6/E7 coding sequences were expressed in HFKs from two or three independent donors. Reduced p53 levels and low-level hTERT expression in early-passage cells, as seen in HPV16-, -31-, -33-, and -35-, and to a lesser extent HPV18-transduced HFKs, was associated with continuous growth and an increased immortalization capacity. Less frequent immortalization by HPV45 and -51 and immortalization by HPV66 and -70 was preceded by an intervening period of strongly reduced growth (crisis) without prior increase in hTERT expression. Immortalization by HPV59 was also preceded by a period crisis, despite the onset of low hTERT expression at early passage. HPV52 triggered an extended life span but failed to induce immortality. Variations in p53 and pRb levels were not correlated with differences in alternative E6/E7 mRNA splicing in all hrHPV-transduced HFKs. On collagen rafts, transductants showed disturbed differentiation reminiscent of precancerous lesions. In conclusion, in vitro oncogenic capacities differ between the established hrHPV types, and both some established and probable hrHPV types display weak or moderate immortalization potential.
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8
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Wilting SM, Verlaat W, Jaspers A, Makazaji NA, Agami R, Meijer CJLM, Snijders PJF, Steenbergen RDM. Methylation-mediated transcriptional repression of microRNAs during cervical carcinogenesis. Epigenetics 2013; 8:220-8. [PMID: 23324622 DOI: 10.4161/epi.23605] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Deregulated expression of microRNAs (miRNAs) is common and biologically relevant in cervical carcinogenesis and appears only partly related to chromosomal changes. We recently identified 32 miRNAs showing decreased expression in high-grade cervical intraepithelial neoplasia (CIN) and carcinomas not associated with a chromosomal loss, 6 of which were located within a CpG island. This study aimed to investigate to what extent these miRNAs are subject to DNA methylation-mediated transcriptional repression in cervical carcinogenesis. Methylation-specific PCR (MSP) analysis on a cell line panel representing different stages of human papillomavirus (HPV) induced transformation revealed an increase in methylation of hsa-miR-149, -203 and -375 with progression to malignancy, whereas expression of these miRNAs was restored upon treatment with a demethylating agent. All three miRNAs showed significantly increased levels of methylation in cervical carcinomas, whereas methylation levels of hsa-miR-203 and -375 were also significantly increased in high-grade CIN. A pilot analysis showed that increased hsa-miR-203 methylation was also detectable in HPV-positive cervical scrapes of women with high-grade CIN compared with controls. Similar to recent findings on hsa-miR-375, ectopic expression of hsa-miR-203 in cervical cancer cells decreased both the proliferation rate and anchorage independent growth. We found evidence for methylation-mediated transcriptional repression of hsa-miR-149, -203 and -375 in cervical cancer. Methylation of the latter two was already apparent in precancerous lesions and represent functionally relevant events in HPV-mediated transformation. Increased hsa-miR-203 methylation was detectable in scrapes of women with high-grade CIN, indicating that methylated miRNAs may provide putative markers to assess the presence of (pre)cancerous lesions.
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Affiliation(s)
- Saskia M Wilting
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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9
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Altered microRNA expression associated with chromosomal changes contributes to cervical carcinogenesis. Oncogene 2012; 32:106-16. [DOI: 10.1038/onc.2012.20] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Backsch C, Rudolph B, Steinbach D, Scheungraber C, Liesenfeld M, Häfner N, Hildner M, Habenicht A, Runnebaum IB, Dürst M. An integrative functional genomic and gene expression approach revealed SORBS2 as a putative tumour suppressor gene involved in cervical carcinogenesis. Carcinogenesis 2011; 32:1100-6. [PMID: 21602178 DOI: 10.1093/carcin/bgr093] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Human papillomavirus (HPV) types 16 and 18 are known to play a major role in cervical carcinogenesis. However, additional genetic alterations are required for the development and progression of cervical cancer. Our aim was to identify genes which are consistently down-regulated in cervical cancers (CxCa) and which are likely to contribute to malignant transformation. Microarray analyses of RNA from high-grade cervical precancers (CIN2/3) and CxCa were performed to screen for putative tumour suppressor genes (TSG) in predefined regions on chromosomes 4 and 10. Validation of the candidate genes was done by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in 16 normal cervical tissues, 14 CIN2/3 and 16 CxCa. The two most promising genes, SORBS2 and CALML5, were expressed ectopically in various cell lines in order to analyse their functional activity. Reconstitution of SORBS2 expression resulted in a significant reduction in cell proliferation, colony formation and anchorage-independent growth in CaSki, HPKII and HaCaT cells, whereby anchorage-independent growth could only be investigated for CaSki cells. SORBS2 had no effect on cell migration. In contrast, reconstitution of CALML5 expression did not influence the phenotype of all cell lines tested. None of the genes could induce senescence or apoptosis. Our results underline a possible role of SORBS2 as a TSG in cervical carcinogenesis.
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Affiliation(s)
- Claudia Backsch
- Klinik für Frauenheilkunde und Geburtshilfe, Abteilung Frauenheilkunde, Universitätsklinikum Jena, Bachstrasse 18, 07743 Jena, Germany
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11
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Identification of PITX1 as a TERT suppressor gene located on human chromosome 5. Mol Cell Biol 2011; 31:1624-36. [PMID: 21300782 DOI: 10.1128/mcb.00470-10] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Telomerase, a ribonucleoprotein enzyme that maintains telomere length, is crucial for cellular immortalization and cancer progression. Telomerase activity is attributed primarily to the expression of telomerase reverse transcriptase (TERT). Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line B16F10, we previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression (H. Kugoh, K. Shigenami, K. Funaki, J. Barrett, and M. Oshimura, Genes Chromosome Cancer 36:37-47, 2003). To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase-negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here, we report the identification of PITX1, whose expression leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We show that three and one binding site within the hTERT and mtert promoters, respectively, that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity.
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Qi DL, Ohhira T, Oshimura M, Kugoh H. Human chromosome 5 carries a transcriptional regulator of human telomerase reverse transcriptase (hTERT). Biochem Biophys Res Commun 2010; 398:695-701. [PMID: 20621064 DOI: 10.1016/j.bbrc.2010.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 07/02/2010] [Indexed: 12/11/2022]
Abstract
Telomerase activation is crucial for cells that tend to be immortalized. Increased telomerase activity is correlated with upregulation of telomerase reverse transcriptase (TERT) expression. In most human somatic cells, hTERT expression is suppressed by multiple factors. We have previously shown that human chromosome 5 carries a possible suppressor of mouse tert mtert expression in a mouse melanoma cell line, B16-F10 cells. However, the function of the transcriptional regulator of TERT on this chromosome remains unclear. To examine the functional role of a putative hTERT regulator(s) on this chromosome, we transferred human chromosome 5 in a human melanoma cell line, A2058 cells by microcell-mediated chromosome transfer (MMCT). Microcell hybrid clones with an introduced chromosome 5, but not chromosome 10, showed a remarkable decrease in the growth rate with an obvious cellular morphological alteration and eventually cellular senescence. Moreover, this phenomenon was accompanied by a reduction of hTERT expression and telomerase activity. Most importantly, we found that transcriptional suppression of hTERT by the introduction of chromosome 5 is largely mediated by regulating hTERT promoter activity. Furthermore, the hTERT promoter region between -1623 and -1047 was responsible for this function. These results provide evidence that transcriptional regulator(s) of the hTERT is carried on human chromosome 5 as an endogenous mechanism of hTERT suppression.
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Affiliation(s)
- Dong-Lai Qi
- Department of Biomedical Science, Graduate School of Medical Science, and Chromosome Engineering Research Center, Tottori University, 86 Nishicho, Yonago 683-8503, Japan
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de Wilde J, Kooter JM, Overmeer RM, Claassen-Kramer D, Meijer CJLM, Snijders PJF, Steenbergen RDM. hTERT promoter activity and CpG methylation in HPV-induced carcinogenesis. BMC Cancer 2010; 10:271. [PMID: 20534141 PMCID: PMC2904279 DOI: 10.1186/1471-2407-10-271] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 06/09/2010] [Indexed: 12/23/2022] Open
Abstract
Background Activation of telomerase resulting from deregulated hTERT expression is a key event during high-risk human papillomavirus (hrHPV)-induced cervical carcinogenesis. In the present study we examined hTERT promoter activity and its relation to DNA methylation as one of the potential mechanisms underlying deregulated hTERT transcription in hrHPV-transformed cells. Methods Using luciferase reporter assays we analyzed hTERT promoter activity in primary keratinocytes, HPV16- and HPV18-immortalized keratinocyte cell lines and cervical cancer cell lines. In the same cells as well as cervical specimens we determined hTERT methylation by bisulfite sequencing analysis of the region spanning -442 to +566 (relative to the ATG) and quantitative methylation specific PCR (qMSP) analysis of two regions flanking the hTERT core promoter. Results We found that in most telomerase positive cells increased hTERT core promoter activity coincided with increased hTERT mRNA expression. On the other hand basal hTERT promoter activity was also detected in telomerase negative cells with no or strongly reduced hTERT mRNA expression levels. In both telomerase positive and negative cells regulatory sequences flanking both ends of the core promoter markedly repressed exogenous promoter activity. By extensive bisulfite sequencing a strong increase in CpG methylation was detected in hTERT positive cells compared to cells with no or strongly reduced hTERT expression. Subsequent qMSP analysis of a larger set of cervical tissue specimens revealed methylation of both regions analyzed in 100% of cervical carcinomas and 38% of the high-grade precursor lesions, compared to 9% of low grade precursor lesions and 5% of normal controls. Conclusions Methylation of transcriptionally repressive sequences in the hTERT promoter and proximal exonic sequences is correlated to deregulated hTERT transcription in HPV-immortalized cells and cervical cancer cells. The detection of DNA methylation at these repressive regions may provide an attractive biomarker for early detection of cervical cancer.
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Affiliation(s)
- Jillian de Wilde
- Department of Pathology, Unit of Molecular Pathology, VU University Medical Center, PO box 7057, 1007 MB Amsterdam, the Netherlands
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14
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Kyo S, Takakura M, Fujiwara T, Inoue M. Understanding and exploiting hTERT promoter regulation for diagnosis and treatment of human cancers. Cancer Sci 2008; 99:1528-38. [PMID: 18754863 PMCID: PMC11158053 DOI: 10.1111/j.1349-7006.2008.00878.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Telomerase activation is a critical step for human carcinogenesis through the maintenance of telomeres, but the activation mechanism during carcinogenesis remains unclear. Transcriptional regulation of the human telomerase reverse transcriptase (hTERT) gene is the major mechanism for cancer-specific activation of telomerase, and a number of factors have been identified to directly or indirectly regulate the hTERT promoter, including cellular transcriptional activators (c-Myc, Sp1, HIF-1, AP2, ER, Ets, etc.) as well as the repressors, most of which comprise tumor suppressor gene products, such as p53, WT1, and Menin. Nevertheless, none of them can clearly account for the cancer specificity of hTERT expression. The chromatin structure via the DNA methylation or modulation of nucleosome histones has recently been suggested to be important for regulation of the hTERT promoter. DNA unmethylation or histone methylation around the transcription start site of the hTERT promoter triggers the recruitment of histone acetyltransferase (HAT) activity, allowing hTERT transcription. These facts prompted us to apply these regulatory mechanisms to cancer diagnostics and therapeutics. Telomerase-specific replicative adenovirus (Telomelysin, OBP-301), in which E1A and E1B genes are driven by the hTERT promoter, has been developed as an oncolytic virus that replicates specifically in cancer cells and causes cell death via viral toxicity. Direct administration of Telomelysin was proved to effectively eradicate solid tumors in vivo, without apparent adverse effects. Clinical trials using Telomelysin for cancer patients with progressive stages are currently ongoing. Furthermore, we incorporated green fluorescent protein gene (GFP) into Telomelysin (TelomeScan, OBP-401). Administration of TelomeScan into the primary tumor enabled the visualization of cancer cells under the cooled charged-coupled device (CCD) camera, not only in primary tumors but also the metastatic foci. This technology can be applied to intraoperative imaging of metastatic lymphnodes. Thus, we found novel tools for cancer diagnostics and therapeutics by utilizing the hTERT promoter.
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Affiliation(s)
- Satoru Kyo
- Department of Obstetrics and Gynecology, Kanazawa University, Graduate School of Medical Science, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8641, Japan.
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Penile cancer: epidemiology, pathogenesis and prevention. World J Urol 2008; 27:141-50. [DOI: 10.1007/s00345-008-0302-z] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Accepted: 06/09/2008] [Indexed: 11/25/2022] Open
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de Wilde J, Wilting SM, Meijer CJLM, van de Wiel MA, Ylstra B, Snijders PJF, Steenbergen RDM. Gene expression profiling to identify markers associated with deregulated hTERT in HPV-transformed keratinocytes and cervical cancer. Int J Cancer 2008; 122:877-88. [PMID: 17960611 DOI: 10.1002/ijc.23210] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Although high-risk human papillomavirus (HPV) infection plays a major role in the development of cervical cancer, additive oncogenic events are involved as well. One key event involves increased activity of telomerase resulting from a deregulated expression of its catalytic subunit hTERT. Our previous microcell-mediated chromosome transfer studies revealed that introduction of human chromosome 6 in the HPV16-immortalized keratinocyte cell line FK16A and in the HPV16-containing cervical cancer cell line SiHa induced growth arrest, resulting from a repression of hTERT mRNA expression and telomerase activity. Here, this model was used to analyze expression profiles associated with hTERT deregulation in HPV-transformed cells. Microarray expression analysis of 12 FK16A/chromosome 6 hybrids, 4 of which were negative for endogenous hTERT and 8 of which were positive for endogenous hTERT, resulted in the identification of 164 differentially expressed genes. Differential expression of a selection of 5 genes was verified by real-time RT-PCR. Of these 164 genes, 32 were also differentially expressed in other HPV transformed cells with deregulated hTERT. For 2 of these genes, encoding AQP3 and MGP, altered expression in hTERT positive cervical carcinomas was confirmed by real-time RT-PCR and immunohistochemistry, respectively. Moreover, increased MGP protein expression was significantly more frequent in high-grade cervical premalignant lesions with elevated hTERT mRNA expression compared to those without. In summary, we identified 32 candidate biomarkers for deregulated hTERT mRNA expression, which may enable the identification of cervical premalignant lesions that are at highest risk to progress to invasive cancer.
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Affiliation(s)
- Jillian de Wilde
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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Abstract
We aimed to link DNA methylation events occurring in cervical carcinomas to distinct stages of HPV-induced transformation. Methylation specific-multiplex ligation-dependent probe amplification (MS-MLPA) analysis of cervical carcinomas revealed promoter methylation of 12 out of 29 tumour suppressor genes analysed, with MGMT being most frequently methylated (92%). Subsequently, consecutive stages of HPV16/18-transfected keratinocytes (n=11), ranging from pre-immortal to anchorage-independent phenotypes, were analysed by MS-MLPA. Whereas no methylation was evident in pre-immortal cells, progression to anchorage independence was associated with an accumulation of frequent methylation events involving five genes, all of which were also methylated in cervical carcinomas. TP73 and ESR1 methylation became manifest in early immortal cells followed by RARbeta and DAPK1 methylation in late immortal passages. Complementary methylation of MGMT was related to anchorage independence. Analysis of nine cervical cancer cell lines, representing the tumorigenic phenotype, revealed in addition to these five genes frequent methylation of CADM1, CDH13 and CHFR. In conclusion, eight recurrent methylation events in cervical carcinomas could be assigned to different stages of HPV-induced transformation. Hence, our in vitro model system provides a valuable tool to further functionally address the epigenetic alterations that are common in cervical carcinomas.
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18
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Snijders PJF, Steenbergen RDM, Heideman DAM, Meijer CJLM. HPV-mediated cervical carcinogenesis: concepts and clinical implications. J Pathol 2006; 208:152-64. [PMID: 16362994 DOI: 10.1002/path.1866] [Citation(s) in RCA: 297] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Persistent infection with a high-risk human papillomavirus (hrHPV) is generally accepted as a necessary cause of cervical cancer. However, cervical cancer is a rare complication of an hrHPV infection since most such infections are transient, not even giving rise to cervical lesions. On average, it takes 12-15 years before a persistent hrHPV infection may ultimately, via consecutive premalignant stages (ie CIN lesions), lead to an overt cervical carcinoma. This argues that HPV-induced cervical carcinogenesis is multi-step in nature. In this review, the data from hrHPV-mediated in vitro transformation studies and those obtained from analysis of clinical specimens have been merged into a cervical cancer progression model. According to this model, a crucial decision maker in the early stages following infection involves individual susceptibility for certain HPV types depending on the genetic make-up of immune surveillance determinants. Once a CIN lesion has developed, altered transcriptional regulation of the viral E6/E7 oncogenes, resulting in genomic instability and distinguishing the process of cell transformation from a productive viral infection, probably provides the subsequent important step towards malignancy. The additional (epi)genetic alterations that subsequently accumulate in high-grade CIN lesions may result in overt malignancy via immortality and growth conditions that gradually become less sensitive to growth-modulating influences mediated by cytokines and cell-cell and cell-matrix adhesions. The potential implications of hrHPV testing and some other biomarkers deduced from this model for cervical screening and the clinical management of CIN disease are also discussed.
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Affiliation(s)
- Peter J F Snijders
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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19
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Breuer RHJ, Postmus PE, Smit EF. Molecular pathology of non-small-cell lung cancer. Respiration 2005; 72:313-30. [PMID: 15942304 DOI: 10.1159/000085376] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Accepted: 07/29/2004] [Indexed: 01/22/2023] Open
Abstract
The molecular basis of lung carcinogenesis must be understood more fully and exploited to enhance survival rates of patients suffering from lung cancer. In this review we will discuss the major molecular alterations that occur in lung cancer. Emphasis is placed on alterations that occur early during carcinogenesis since they might be relevant for future screening programs. Finally we will shortly review new approaches that are used to study the molecular pathology of lung cancer and how they can be applied in a clinical setting.
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Affiliation(s)
- R H J Breuer
- Department of Pulmonology, Free University Medical Center, Amsterdam, The Netherlands
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20
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Meaburn KJ, Parris CN, Bridger JM. The manipulation of chromosomes by mankind: the uses of microcell-mediated chromosome transfer. Chromosoma 2005; 114:263-74. [PMID: 16133353 DOI: 10.1007/s00412-005-0014-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 05/29/2005] [Accepted: 06/21/2005] [Indexed: 12/20/2022]
Abstract
Microcell-mediated chromosome transfer (MMCT) was a technique originally developed in the 1970s to transfer exogenous chromosome material into host cells. Although, the methodology has not changed considerably since this time it is being used to great success in progressing several different fields in modern day biology. MMCT is being employed by groups all over the world to hunt for tumour suppressor genes associated with specific cancers, DNA repair genes, senescence-inducing genes and telomerase suppression genes. Some of these genomic discoveries are being investigated as potential treatments for cancer. Other fields have taken advantage of MMCT, and these include assessing genomic stability, genomic imprinting, chromatin modification and structure and spatial genome organisation. MMCT has also been a very useful method in construction and manipulation of artificial chromosomes for potential gene therapies. Indeed, MMCT is used to transfer mainly fragmented mini-chromosome between cell types and into embryonic stem cells for the construction of transgenic animals. This review briefly discusses these various uses and some of the consequences and advancements made by different fields utilising MMCT technology.
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Affiliation(s)
- Karen J Meaburn
- Cell and Chromosome Biology Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge UB8 3PH, UK
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21
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Steenbergen RDM, de Wilde J, Wilting SM, Brink AATP, Snijders PJF, Meijer CJLM. HPV-mediated transformation of the anogenital tract. J Clin Virol 2005; 32 Suppl 1:S25-33. [PMID: 15753009 DOI: 10.1016/j.jcv.2004.11.019] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Accepted: 11/01/2004] [Indexed: 12/12/2022]
Abstract
Infection with high-risk human papillomavirus (HR-HPV) has been associated with intraepithelial neoplasia and carcinomas at various sites of the anogenital tract, including the cervix, vulva, vagina, penis and anus. Although HR-HPV is a necessary cause for cervical cancer, the majority of anal cancers and a subset of cancers at other genital sites, additional (epi)genetic events are required for malignant transformation. HPV-mediated transformation of human epithelial cells has been recognized as a multi-step process resulting from deregulated transcription of the viral oncogenes E6 and E7 in the proliferating cells. Interference of E6 and E7 with cell cycle regulators induces genetic instability, which drives the continuous selection of oncogenic alterations providing cells with a malignant phenotype. Early genetic events during cervical carcinogenesis associated with immortalization, include deletions at chromosomes 3p, 6 and 10p, whereas amongst others gain of chromosome 3q, loss of chromosome 11 and epigenetic alterations such as inactivation of the TSLC1 tumor suppressor gene represent later events associated with tumor invasion.
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Affiliation(s)
- Renske D M Steenbergen
- Department of Pathology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
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22
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Tanaka H, Horikawa I, Barrett JC, Oshimura M. Evidence for inactivation of distinct telomerase repressor genes in different types of human cancers. Int J Cancer 2005; 115:653-7. [PMID: 15688423 DOI: 10.1002/ijc.20879] [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] [Indexed: 11/09/2022]
Abstract
Telomerase activation, a critical event in human carcinogenesis, may result from defects in telomerase-repressing mechanisms. Data from microcell-mediated chromosome transfer (MMCT) suggests the presence of telomerase repressor genes that become inactivated during carcinogenic processes. The transfer of a normal human chromosome 3 represses telomerase activity of both human renal cell carcinoma (RCC) and breast carcinoma (BC) cells. For a genetic complementation analysis of telomerase repression, 2 RCC cell lines (KC12 and RCC23) and a BC cell line (21NT) were used to make somatic cell hybrids. All of the self-hybrids (KC12 x KC12 and 21NT x 21NT) and hybrids from 2 RCC cell lines (KC12 x RCC23) expressed the telomerase activity similarly to their parental cells, excluding the possibility of a ploidy-associated change in telomerase activity and suggesting the same genetic defect shared by the 2 RCC cell lines. In contrast, the fusion of BC and RCC cells (21NT x KC12 and 21NT x RCC23) produced a significant number of telomerase-negative hybrids, suggesting that the RCC and BC cells have different defects in the telomerase repression, which are functionally corrected through genetic complementation in the hybrids. This notion was supported by the mapping of the RCC telomerase repressor gene to a 5.7-Mb region on 3p21, which is different from the candidate region for the BC telomerase repressor gene on the same chromosomal band. These findings provide direct evidence for inactivation of distinct telomerase repressor genes in different types of human cancers and may have implications in the tissue-specific regulation of telomerase during human development and carcinogenesis.
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Affiliation(s)
- Hiromi Tanaka
- Department of Molecular and Cell Genetics, School of Life Sciences, Faculty of Medicine, Tottori University, Tottori, Japan.
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23
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Simbulan-Rosenthal CM, Trabosh V, Velarde A, Chou FP, Daher A, Tenzin F, Tokino T, Rosenthal DS. Id2 protein is selectively upregulated by UVB in primary, but not in immortalized human keratinocytes and inhibits differentiation. Oncogene 2005; 24:5443-58. [PMID: 16007217 DOI: 10.1038/sj.onc.1208709] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Solar ultraviolet B (UVB) acts as both an initiator and promoter in models of multistage skin carcinogenesis. We found that, whereas UVB induces apoptosis in human papillomavirus-16 E6/7-immortalized keratinocytes, it inhibits markers of differentiation in human foreskin keratinocytes (HFK). Potential mechanisms for this differential response were examined by DNA microarray, which revealed that UVB alters the expression of three of the four human inhibitor of differentiation/DNA binding (Id) proteins that comprise a class of helix-loop-helix family of transcription factors involved in proliferation, differentiation, apoptosis, and carcinogenesis. These results were verified by RT-PCR and immunoblot analysis of control and UVB-irradiated primary and immortalized keratinocytes. Whereas Id1 was downregulated in both cell types, Id2 expression was upregulated in primary HFK, but not immortalized cells. In contrast, Id3 expression was significantly increased only in immortalized cells. The differential expression pattern of Id2 in response to UVB was recapitulated in reporter constructs containing the 5' regulatory regions of this gene. Id2 promoter activity increased in response to UVB in HFK, but not in immortalized cells. To identify the regulatory elements in the Id2 promoter that mediate transcriptional activation by UVB in HFK, promoter deletion/mutation analysis was performed. Deletion analysis revealed that transactivation involves a 166 bp region immediately upstream to the Id2 transcriptional start site and is independent of c-Myc. The consensus E twenty-six (ETS) binding site at -120 appears to mediate UVB transcriptional activation of Id2 because point mutations at this site completely abrogated this response. Chromatin immunoprecipitation and electrophoretic mobility-shift assays verified that the Id2 promoter interacts with known Id2 promoter (ETS) binding factors Erg1/2 and Fli1, but not with c-Myc; and this interaction is enhanced after UVB exposure. Similar to the effects of UVB exposure, ectopic expression of Id2 protein in primary HFK resulted in inhibition of differentiation, as shown by decreased levels of the terminal differentiation marker keratin K1 and inhibition of involucrin crosslinking. Reduction of Id2 expression by small interfering RNAs attenuated the UVB-induced inhibition of differentiation in these cells. These results suggest that UVB-induced inhibition of differentiation of primary HFK is at least, in part, due to the upregulation of Id2, and that upregulation of Id2 by UVB might predispose keratinocytes to carcinogenesis by preventing their normal differentiation program.
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Affiliation(s)
- Cynthia M Simbulan-Rosenthal
- Department of Biochemistry and Molecular Biology, Georgetown University, School of Medicine, Washington, DC 20007, USA
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24
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Alazawi W, Pett M, Strauss S, Moseley R, Gray J, Stanley M, Coleman N. Genomic imbalances in 70 snap-frozen cervical squamous intraepithelial lesions: associations with lesion grade, state of the HPV16 E2 gene and clinical outcome. Br J Cancer 2005; 91:2063-70. [PMID: 15545968 PMCID: PMC2409784 DOI: 10.1038/sj.bjc.6602237] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Host genomic abnormalities may determine the natural history of cervical squamous intraepithelial lesions (SILs). We undertook comparative genomic hybridisation analysis of epithelium carefully microdissected from 70 cervical SILs, the largest series to date. In contrast to previous studies, we used frozen sections for optimal DNA quality and examined whether patterns of DNA copy number imbalance (CNI) are characteristic of SIL grade, human papillomavirus (HPV) status and postoperative recurrence. We identified more CNIs in cervical SIL than previously described, with more CNIs per case in high-grade squamous intraepithelial lesion (HG-SIL) than in low-grade squamous intraepithelial lesion (LG-SIL) (P=0.04). While some CNIs were seen at similar frequencies in HG-SIL and LG-SIL, others, including gain on 1q, 3q and 16q, were found frequently in HG-SIL but not in LG-SIL. There were significantly more CNIs per case in HG-SILs showing loss of the HPV16 E2 gene (a repressor of viral oncogene transcription) (P=0.026) and in HG-SILs that subsequently recurred (P=0.04). Our data are consistent with sequential acquisition of CNIs in cervical SIL progression. Higher frequency of CNI in association with E2 gene loss supports in vitro evidence that high-risk HPV integration is associated with genomic instability. Further investigation of the clinical value of specific host genomic abnormalities in cervical SIL is warranted.
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Affiliation(s)
- W Alazawi
- Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1DQ, UK
| | - M Pett
- Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1DQ, UK
| | - S Strauss
- Health Protection Agency, Colindale Avenue, London NW9 5HT, UK
| | - R Moseley
- Department of Histopathology, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - J Gray
- Health Protection Agency, Colindale Avenue, London NW9 5HT, UK
| | - M Stanley
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1DQ, UK
| | - N Coleman
- Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1DQ, UK
- Department of Histopathology, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
- Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK. E-mail:
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25
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Backsch C, Rudolph B, Kühne-Heid R, Kalscheuer V, Bartsch O, Jansen L, Beer K, Meyer B, Schneider A, Dürst M. A region on human chromosome 4 (q35.1→qter) induces senescence in cell hybrids and is involved in cervical carcinogenesis. Genes Chromosomes Cancer 2005; 43:260-72. [PMID: 15838843 DOI: 10.1002/gcc.20192] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Human papillomavirus (HPV) types 16 and 18 are known to play a major role in cervical carcinogenesis. Additional genetic alterations are required for the development and progression of cervical cancer. Previously, we showed that the introduction of an entire human chromosome 4 into HPV-immortalized cells by microcell-mediated chromosome transfer (MMCT) can induce senescence in cell hybrids. In the present study, we established eight new murine donor cell lines harboring different fragments of the human chromosome 4. These were tested for their ability to induce senescence by MMCT into HPV16-immortalized keratinocytes (HPK II) and cervical carcinoma cells (HeLa). By exclusion, we could identify a region for a putative senescence gene or genes at 4q35.1-->qter. Further evidence that this locus may be involved in cervical carcinogenesis was obtained by studying sections of high-grade cervical intraepithelial neoplasias (CIN2/3) and cervical cancers from 87 women using a combination of interphase fluorescence in situ hybridization (I-FISH) and microsatellite PCR. I-FISH indicated copy number loss at 4q34-->qter. Microsatellite analysis showed that loss of one or more alleles at chromosome 4 was more frequent in the cervical carcinomas than in the CINs. Loss of heterozygosity (LOH) affected four areas, D4S412 (4p16.3), D4S2394 (4q28.2), D4S3041 (4q32.3), and D4S408 (4q35.1), and was highest at D4S408. LOH at terminal 4q has been reported previously for cervical carcinomas and other human malignancies. This is the first report associating allelic loss at 4q34-->qter with high-grade intraepithelial neoplasia and cervical carcinoma, and the first experimental evidence that this locus or these loci can induce senescence in cervical carcinoma cells and HPV16-immortalized cells.
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Affiliation(s)
- Claudia Backsch
- Gynäkologische Molekularbiologie, Abteilung Frauenheilkunde, Frauenklinik der Friedrich-Schiller-Universität Jena, Germany
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26
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Steenbergen RDM, Kramer D, Braakhuis BJM, Stern PL, Verheijen RHM, Meijer CJLM, Snijders PJF. TSLC1 gene silencing in cervical cancer cell lines and cervical neoplasia. J Natl Cancer Inst 2004; 96:294-305. [PMID: 14970278 DOI: 10.1093/jnci/djh031] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Cervical carcinogenesis is initiated by infection with high-risk (i.e., carcinogenic) human papillomavirus (HPV) types. The subsequent progression from premalignant cervical intraepithelial neoplasia (CIN) to invasive cancer is driven by both genetic and epigenetic processes. We assessed the role of the gene encoding the adhesion molecule tumor suppressor in lung cancer 1 (TSLC1) in this progression. METHODS We analyzed TSLC1 gene expression by real-time quantitative reverse transcription-polymerase chain reaction, promoter methylation by sodium bisulfite genomic DNA sequencing, and allelic loss by microsatellite analysis in primary keratinocytes, in four non-tumorigenic HPV-immortalized human keratinocyte cell lines, and in 11 human cervical cancer cell lines that were positive for a high-risk HPV DNA type and in normal cervical epithelial cells. We transfected cervical cancer SiHa cells that did not express TSLC1 mRNA with an expression vector containing the TSLC1 complementary DNA (cDNA) or an empty vector and analyzed transfectants for anchorage-independent growth and tumorigenicity in nude mice. We also examined TSLC1 promoter methylation in premalignant cervical lesions and in cervical carcinomas and smears. All statistical tests were two-sided. RESULTS TSLC1 mRNA was strongly reduced, relative to levels in primary keratinocytes, or absent in 10 (91%) of 11 cervical carcinoma cell lines but in none (0%) of the four HPV-immortalized cell lines (difference = 91%, 95% confidence interval [CI] = 74% to 100%; P =.004). The TSLC1 promoter was hypermethylated, relative to normal foreskin and cervical epithelial cells, in nine (82%) of the 11 cervical carcinoma cell lines but in none (0%) of the four HPV-immortalized cell lines (difference = 82%, 95 CI = 59% to 100%; P =.01). Seven (88%, 95% CI = 47% to 100%) of the eight SiHa/TSLC1 transfectants displayed a marked reduction in anchorage-independent growth (i.e., 0-100 colonies per 5000 cells) compared with none of the four (0%, 95% CI = 0% to 60%) SiHa transfectants bearing the empty vector (i.e., SiHa/hygro transfectants; difference = 88%, 95% CI = 65% to 100%; P =.01) or untransfected SiHa cells. All seven mice (100%, 95% CI = 59% to 100%) injected with untransfected SiHa cells or SiHa/hygro transfectants displayed tumors of at least 50 mm(3) by 2-6 weeks after injection compared with none of eight mice (0%, 95% CI = 0% to 37%) injected with the SiHa/TSLC1 transfectants (difference = 100%, 95% CI = 68% to 100%; P<.001). We detected TSLC1 promoter hypermethylation in seven (35%, 95% CI = 15% to 59%) of 20 high-grade CIN lesions (i.e., CIN II and III) and in 30 (58%, 95% CI = 43% to 71%) of 52 cervical squamous cell carcinomas compared with none (0%, 95% CI = 0% to 34%) of nine normal cervical epithelial biopsy samples and none (0%, 95% CI = 0% to 22%) of 12 CIN I lesions (P<.001 for cervical squamous cell cancer versus normal epithelial biopsy samples plus CIN I lesions). CONCLUSIONS TSLC1 gene silencing via promoter hypermethylation is a frequent event in the progression from high-risk HPV-containing, high-grade CIN lesions to invasive cervical cancer.
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MESH Headings
- Animals
- Cell Adhesion Molecule-1
- Cell Adhesion Molecules
- Cell Line, Tumor
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/pathology
- Cervix Uteri/cytology
- Cervix Uteri/pathology
- Chromosomes, Human, Pair 11
- Cloning, Molecular
- DNA Methylation
- DNA, Complementary/analysis
- DNA, Viral/analysis
- Down-Regulation
- Female
- Gene Expression Regulation, Neoplastic
- Gene Silencing
- Genes, Tumor Suppressor
- Humans
- Immunoglobulins
- Keratinocytes/metabolism
- Loss of Heterozygosity
- Membrane Proteins
- Mice
- Mice, Nude
- Microsatellite Repeats
- Papillomaviridae/genetics
- Promoter Regions, Genetic
- Proteins/genetics
- Proteins/metabolism
- RNA, Messenger/analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sulfates/metabolism
- Transfection
- Tumor Suppressor Proteins
- Uterine Cervical Neoplasms/genetics
- Uterine Cervical Neoplasms/pathology
- Uterine Cervical Dysplasia/genetics
- Uterine Cervical Dysplasia/pathology
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Affiliation(s)
- Renske D M Steenbergen
- Department of Pathology, Unit of Molecular Pathology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
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27
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Doherty AMO, Fisher EMC. Microcell-mediated chromosome transfer (MMCT): small cells with huge potential. Mamm Genome 2004; 14:583-92. [PMID: 14629108 DOI: 10.1007/s00335-003-4002-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microcell-mediated chromosome transfer (MMCT) is a technique that has been in use since the 1970s for the fusion of microcells, containing single or a small number of chromosomes, with whole cells, and the subsequent selection of the hybrids. MMCT can be carried out with somatic cells, embryonic carcinoma (EC) or embryonic stem (ES) cell recipients, to study in vitro or in vivo effects of the transferred genetic material. These effects may be unpredictable--do the transferred genes function normally while in the regulatory milieu of the host cell? Will epigenetic effects become apparent, and how will these alter gene expression? What happens to the host cell phenotype? Here, we present a review of MMCT in which we argue that, although this is an old technique, its adaptability and efficiency make it an excellent method for the dissection of gene function and dysfunction in a very wide range of current systems.
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Affiliation(s)
- Aideen M O Doherty
- Department of Neurodegenerative Disease, Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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28
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Siwicki JK, Berglund M, Rygier J, Pienkowska-Grela B, Grygalewicz B, Degerman S, Golovleva I, Chrzanowska KH, Lagercrantz S, Blennow E, Roos G, Larsson C. Spontaneously immortalized human T lymphocytes develop gain of chromosomal region 2p13-24 as an early and common genetic event. Genes Chromosomes Cancer 2004; 41:133-44. [PMID: 15287026 DOI: 10.1002/gcc.20059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
To gain further insight into the molecular events responsible for the extended life span and immortalization of human lymphoid cells, we analyzed a series of spontaneously immortalized, IL2-dependent human T-cell lines using molecular cytogenetic techniques. Two of the cell lines were derived from normal spleen and three from patients with Nijmegen breakage syndrome (NBS), a recessive disorder characterized by a high incidence of lymphoid malignancies. Here we show that spontaneous immortalization of the five T-cell lines was associated with the acquisition of copy number gains involving chromosomal region 2p13-24 as common early alterations. In addition, we found an amplification of 8q21-24 after prolonged propagations in all three NBS-derived cell lines as well as early development of near-tetraploidy in two of these lines. Gains involving the short arm of chromosome 2 recently were found in several lymphoid malignancies. Therefore, the cell lines described here can be used for identification and characterization of genes involved in the pathogenesis of lymphoid neoplasms and would also provide a useful tool for better understanding the mechanisms responsible for cell immortalization.
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Affiliation(s)
- Jan Konrad Siwicki
- Department of Immunology, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
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29
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Snijders PJF, Breuer RHJ, Sutedja TG, Egging M, Voorhorst FJ, Steenbergen RDM, van der Linden HC, Risse EK, Berkhof J, de Vries EGE, van der Zee AGJ, Postmus PE, Meijer CJLM, Smit EF. Elevated hTERT mRNA levels: A potential determinant of bronchial squamous cell carcinoma (in situ). Int J Cancer 2004; 109:412-7. [PMID: 14961580 DOI: 10.1002/ijc.11732] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Expression levels of hTERT mRNA were investigated by RT-PCR in tissue specimens of patients with (Group A) and without (Group B) clinically overt bronchial carcinoma, respectively. Bronchial carcinoma (n = 9) and distant normal (n = 9) specimens were analyzed in Group A. The chance of carcinoma seemed to increase with increasing hTERT mRNA levels (OR = 6.04, 95% CI = 1.02-37). Group B was comprised of 21 patients who underwent autofluorescence bronchoscopy. After analysis of 66 bronchial biopsies the chance of prevalent carcinoma in situ or carcinoma increased with increasing hTERT mRNA levels (OR = 6.19, 95% CI = 1.55-25). Variables like age, gender, smoking history, history of cancer within the airways or the degree of lymphocyte infiltrate in the specimens did not modify this relation. In 7 Group B patients in whom bronchial cancer was diagnosed during follow-up, biopsies taken before cancer diagnosis from both the area of the newly developed tumor and distantly from this area had been analyzed for hTERT expression. The median hTERT mRNA level in the biopsies from the area of future cancer was significantly higher than in biopsies taken from distant sites (p < 0.03). These data indicate that elevated hTERT mRNA is associated with an increased relative risk of prevalent and incident bronchial squamous cell carcinoma (in situ).
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Affiliation(s)
- Peter J F Snijders
- Department of Pathology, Vrije Universiteit Medical Center, Amsterdam, the Netherlands.
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30
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Ferreux E, Lont AP, Horenblas S, Gallee MPW, Raaphorst FM, von Knebel Doeberitz M, Meijer CJLM, Snijders PJF. Evidence for at least three alternative mechanisms targeting the p16INK4A/cyclin D/Rb pathway in penile carcinoma, one of which is mediated by high-risk human papillomavirus. J Pathol 2003; 201:109-18. [PMID: 12950023 DOI: 10.1002/path.1394] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A comprehensive analysis of 53 penile carcinomas was performed to determine which mechanisms might be involved in the disruption of the p16(INK4A)/cyclin D/Rb pathway. To that end, human papillomavirus (HPV) presence, p16(INK4A) expression and promoter methylation, and expression of the BMI-1 polycomb gene product were studied. Sixteen (30%) of the carcinomas were found to harbour high-risk HPV DNA, 15 of which contained HPV 16. HPV 16 E6/E7 oncogene transcripts were detected in 13 (87%) of the carcinomas that contained HPV 16. Strong immunostaining for p16(INK4A) was significantly more frequent in carcinomas that contained high-risk HPV DNA (p < 0.001) and amongst those with HPV 16 DNA, it was more frequent in lesions in which E6/E7 transcripts were detectable (p = 0.029). This supports an active role for HPV E7 in interfering with the p16(INK4A)/cyclin D/Rb pathway. Methylation of the p16(INK4A) promoter or overexpression of the BMI-1 polycomb gene product may provide alternative modes of interference with this pathway. These phenomena were mutually exclusive and found in the absence of HPV in 15% and 10% of the penile carcinomas, respectively. These data indicate that there are at least three plausible mechanisms by which the p16(INK4A)/cyclin D/Rb pathway can become disrupted during penile carcinogenesis.
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Affiliation(s)
- Emmanuelle Ferreux
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
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31
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van Duin M, Steenbergen RDM, de Wilde J, Helmerhorst TJM, Verheijen RHM, Risse EKJ, Meijer CJLM, Snijders PJF. Telomerase activity in high-grade cervical lesions is associated with allelic imbalance at 6Q14-22. Int J Cancer 2003; 105:577-82. [PMID: 12740903 DOI: 10.1002/ijc.11145] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Our study attempts to establish the relationship between telomerase activity and allelic imbalance (AI) on chromosomes 3p and 6 in high-risk HPV-containing cervical lesions. These chromosomes were implicated previously in telomerase regulation in HPV containing immortalized cells and cervical cancer cells. Allelotyping and telomerase analysis were carried out on 28 high-grade cervical lesions (CIN III: n = 20; cervical carcinomas: n = 8), using 23 microsatellite markers on 3p, 6p and 6q. Clear telomerase activity was found in 17 of 28 lesions (61%). Allelic imbalance frequency at 6q14-22 was significantly higher in lesions with detectable telomerase activity, compared to lesions without telomerase activity (p = 0.02). No association was found between telomerase activity and AI at any of the remaining regions studied on 3p and chromosome 6. In addition, in telomerase positive passages of the HPV 16 immortalized cell line FK16A, shown recently to be responsive to chromosome 6 mediated telomerase repression, AI was found in the overlapping region of 6q14-27. These data suggest that 6q14-22 may contain 1 or more genes involved in telomerase deregulation and immortalization during cervical carcinogenesis.
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MESH Headings
- Adult
- Allelic Imbalance
- Carcinoma, Squamous Cell/enzymology
- Carcinoma, Squamous Cell/genetics
- Cell Line, Transformed
- Cell Transformation, Viral/genetics
- Chromosomes, Human, Pair 3/genetics
- Chromosomes, Human, Pair 6/genetics
- DNA, Neoplasm/genetics
- DNA-Binding Proteins
- Female
- Genome, Viral
- Humans
- Keratinocytes/cytology
- Male
- Microsatellite Repeats
- Middle Aged
- Neoplasm Proteins/analysis
- Papillomaviridae/physiology
- Papillomavirus Infections/genetics
- Penis
- RNA, Messenger/analysis
- RNA, Neoplasm/analysis
- Telomerase/analysis
- Telomerase/genetics
- Transfection
- Tumor Virus Infections/genetics
- Uterine Cervical Neoplasms/enzymology
- Uterine Cervical Neoplasms/genetics
- Uterine Cervical Dysplasia/enzymology
- Uterine Cervical Dysplasia/genetics
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Affiliation(s)
- Mark van Duin
- Department of Pathology, Vrije Universiteit Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands
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32
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Horikawa I, Barrett JC. Transcriptional regulation of the telomerase hTERT gene as a target for cellular and viral oncogenic mechanisms. Carcinogenesis 2003; 24:1167-76. [PMID: 12807729 DOI: 10.1093/carcin/bgg085] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Malignant transformation from mortal, normal cells to immortal, cancer cells is generally associated with activation of telomerase and subsequent telomere maintenance. A major mechanism to regulate telomerase activity in human cells is transcriptional control of the telomerase catalytic subunit gene, human telomerase reverse transcriptase (hTERT). Several transcription factors, including oncogene products (e.g. c-Myc) and tumor suppressor gene products (e.g. WT1 and p53), are able to control hTERT transcription when over-expressed, although it remains to be determined whether a cancer-associated alteration of these factors is primarily responsible for the hTERT activation during carcinogenic processes. Microcell-mediated chromosome transfer experiments have provided evidence for endogenous factors that function to repress the telomerase activity in normal cells and are inactivated in cancer cells. At least one of those endogenous telomerase repressors, which is encoded by a putative tumor suppressor gene on chromosome 3p, acts through transcriptional repression of the hTERT gene. The hTERT gene is also a target site for viruses frequently associated with human cancers, such as human papillomavirus (HPV) and hepatitis B virus (HBV). HPV E6 protein contributes to keratinocyte immortalization and carcinogenesis through trans-activation of the hTERT gene transcription. In at least some hepatocellular carcinomas, the hTERT gene is a non-random integration site of HBV genome, which activates in cis the hTERT transcription. Thus, a variety of cellular and viral oncogenic mechanisms converge on transcriptional control of the hTERT gene. Regulation of chromatin structure through the modification of nucleosomal histones may mediate the action of these cellular and viral mechanisms. Further elucidation of the hTERT transcriptional regulation, including identification and characterization of the endogenous repressor proteins, should lead to better understanding of the complex regulation of human telomerase in normal and cancer cells and may open up new strategies for anticancer therapy.
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Affiliation(s)
- Izumi Horikawa
- Laboratory of Biosystems and Cancer, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 37, Room 5046, MSC-4264, Bethesda, MD 20892, USA.
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33
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Fitzsimmons SA, Ireland H, Barr NI, Cuthbert AP, Going JJ, Newbold RF, Parkinson EK. Human squamous cell carcinomas lose a mortality gene from chromosome 6q14.3 to q15. Oncogene 2003; 22:1737-46. [PMID: 12642877 DOI: 10.1038/sj.onc.1206295] [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] [Indexed: 11/09/2022]
Abstract
Normal human keratinocytes possess a finite replicative lifespan. Most advanced squamous cell carcinomas (SCCs), however, are immortal, a phenotype that is associated with p53 and INK4A dysfunction, high levels of telomerase and loss of heterozygosity (LOH) at several genetic loci, suggestive of the dysfunction of other mortality genes. We show here that human chromosome 6 specifically reduces the proliferation or viability of a human SCC line, BICR31, possessing LOH across the chromosome. This was determined by an 88% reduction in colony yield (P<0.001), following the reintroduction of an intact normal chromosome 6 by monochromosome transfer. Deletion analysis of immortal segregants using polymorphic markers revealed the loss of a 2.9 Mbp interval, centred on marker D6S1045 at 6q14.3-q15, in 6/19 segregants. Crucially, allelic losses of this region were not identified in control hybrids constructed between chromosome 6 and the BICR6 SCC cell line that is heterozygous for chromosome 6 and which showed no reduction in colony formation relative to the control chromosome transfers. This indicates that the minimally deleted region at D6S1045 is not the result of fragile sites, a recombination hot spot, or a feature of the monochromosome transfer technique. LOH of D6S1045 was found in 2/9 immortal SCC lines and was part of a minimally deleted region of line BICR19. Furthermore, allelic imbalance, consistent with LOH, was detected in 3/17 advanced SCCs of the tongue. These results suggest the existence of a suppressor of SCC immortality and tumour development at chromosome 6q14.3-q15, which is important to a subset of human SCCs.
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Affiliation(s)
- S A Fitzsimmons
- Beatson Institute for Cancer Research, Cancer Research UK Beatson Laboratories, Glasgow, UK
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Yawata T, Kamino H, Kugoh H, Katoh M, Nomura N, Oishi M, Horikawa I, Barrett JC, Oshimura M. Identification of a </= 600-kb region on human chromosome 1q42.3 inducing cellular senescence. Oncogene 2003; 22:281-90. [PMID: 12527897 DOI: 10.1038/sj.onc.1206143] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The introduction of a human chromosome 1 via microcell-mediated chromosome transfer (MMCT) induces the cellular senescence in mouse melanoma B16-F10 cells. The senescent cells maintained still the telomerase activity, which is frequently associated with immortal growth of human cells, suggesting that a telomerase-independent mechanism is involved in the senescence observed in this mouse cell line. To map the senescence-inducing gene to a specific chromosomal region, we took two experimental approaches: identification of a minimal region with the senescence-inducing activity via MMCT of a series of subchromosomal transferrable fragments (STFs), each consisting of a different profile of human chromosome 1-derived regions, and identification of a region commonly deleted from the transferred chromosome 1 in the revertant clones that escaped cellular senescence. These approaches identified a 2.7-3.0 Mb of senescence-inducing region shared among the active STFs and a 2.4-3.0 Mb of commonly deleted region in the revertant clones. These two regions overlapped each other to map the responsible gene at the 450 to 600-kb interval between UniSTS93710 and D1S3542 on chromosome 1q42.3. This study provides essential information and materials for cloning and characterization of a novel senescence-inducing gene that functions in a telomerase-independent pathway, which is likely to be conserved between mice and humans.
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Affiliation(s)
- Toshio Yawata
- Department of Molecular and Cell Genetics, Faculty of Medicine, School of Life Sciences, Tottori University, Japan
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35
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Kugoh H, Shigenami K, Funaki K, Barrett JC, Oshimura M. Human chromosome 5 carries a putative telomerase repressor gene. Genes Chromosomes Cancer 2003; 36:37-47. [PMID: 12461748 DOI: 10.1002/gcc.10135] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Telomerase, the ribonucleoprotein enzyme that maintains the telomere, is active in human germ and stem cells and in a majority of tumor tissues and immortalized cell lines. In contrast, telomerase activity is not detected in most somatic cells, suggesting that normal human cells contain a regulatory factor(s) to repress this activity. To identify which human chromosomes carry a gene or genes that function as telomerase repressors, we investigated telomerase activity in hybrids of the B16-F10 cell line, which contain individual human chromosomes transferred previously by microcell fusion and therefore represent a hybrid panel for the entire genome except for the Y chromosome. Microcell hybrids with an introduced normal human chromosome 5 showed inhibition of telomerase activity, but clones at a late passage exhibited reactivation of telomerase activity. Reactivation of telomerase activity was accompanied by deletion and/or rearrangement of the transferred human chromosome 5. The introduction of other human chromosomes did not significantly affect the telomerase activity of B16-F10 cells. The effect of suppression of telomerase activity in microcell hybrids containing chromosome 5 was accompanied by a reduction in the level of mTERT mRNA, which encodes a component of the telomerase complex. The putative telomerase repressor gene was mapped to human chromosome bands 5p11-p13 by a combination of functional analysis using transfer of subchromosomal transferable fragments of chromosome 5 into B16-F10 cells and deletion mapping of revertant clones with reactivated telomerase activity. Thus, these results suggest that loss of a gene(s) on this chromosome was responsible for telomerase reactivation, indicating that human chromosome 5 contains a gene or genes that can regulate the expression of mTERT in B16-F10 cells.
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Affiliation(s)
- Hiroyuki Kugoh
- Department of Molecular and Cell Genetics, School of Life Sciences, Faculty of Medicine, Tottori University, Japan
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36
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Bryce SD, Morrison V, Craig NJ, Forsyth NR, Fitzsimmons SA, Ireland H, Cuthbert AP, Newbold RF, Parkinson EK. A mortality gene(s) for the human adenocarcinoma line HeLa maps to a 130-kb region of human chromosome 4q22-q23. Neoplasia 2002; 4:544-50. [PMID: 12407449 PMCID: PMC1503669 DOI: 10.1038/sj.neo.7900268] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2002] [Accepted: 06/26/2002] [Indexed: 11/09/2022]
Abstract
Human chromosome 4 was previously shown to elicit features of senescence when introduced into cell lines that map to complementation group B for senescence, including HeLa cells. Subsequently, a DNA segment encoding the pseudogene Mortality Factor 4 (MORF4) was shown to reproduce some of the effects of the intact chromosome 4 and was suggested to be a candidate mortality gene. We have identified multiple MORF4 alleles in several cell lines and tissues by sequencing and have failed to detect any cancer-specific mutations in three of the complementation group B lines (HeLa, T98G, and J82). Furthermore, MORF4 was heterozygous in these lines. These results question whether MORF4 is the chromosome 4 mortality gene. To map other candidate mortality gene(s) on this chromosome, we employed microcell-mediated monochromosome transfer to introduce either a complete copy, or defined fragments of the chromosome into HeLa cells. The introduced chromosome 4 fragments mapped the mortality gene to a region between the centromere and the marker D4S2975 (4q27), thus excluding MORF4, which maps to 4q33-q34.1. Analysis of microsatellite markers on the introduced chromosome in 59 immortal segregants identified a frequently deleted region, spanning the markers BIR0110 and D4S1557. This defines a new candidate interval of 130 kb at 4q22-q23.
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Affiliation(s)
- Steven D Bryce
- Beatson Institute for Cancer Research, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, Scotland, UK
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37
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Wang N. Methodologies in cancer cytogenetics and molecular cytogenetics. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 115:118-24. [PMID: 12407691 DOI: 10.1002/ajmg.10687] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Various types of cytogenetic and molecular cytogenetic approaches, including conventional banding, fluorescence in situ hybridization (FISH), fiber-FISH, comparative genomic hybridization (CGH), matrix array CGH, chromosome microdissection, and microcell-mediated chromosome transfer are summarized. The rationale, advantage, and limitations of each approach are discussed with respect to research and clinical applications in human neoplasia.
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Affiliation(s)
- Nancy Wang
- School of Rochester, University of Rochester, NY, USA.
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38
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Abstract
For many years it has been widely accepted that stem cells play a crucial role in adult tissue maintenance. The concept that the renewing tissues of the body contain a small subcompartment of self-maintaining stem cells, upon which the entire tissue is dependent, is also now accepted as applicable to all renewing tissues. Gene therapy and tissue engineering are driving considerable interest in the clinical application of such hierarchically organized cellular compartments. Recent initial observations have provided a tantalizing insight into the large pluripotency of these cells. Indeed, scientists are now beginning to talk about the possible totipotency of some adult tissue stem cells. Such work is currently phenomenologic, but analysis of data derived from genomics and proteomics, identifying the crucial control signals involved, will soon provide a further impetus to stem cell biology with far reaching applications. The epidermis with its relatively simple structure, ease of accessibility, and the ability to grow its cells in vitro is one obvious target tissue for testing stem cell manipulation theories. It is crucial, however, that the normal keratinocyte stem cell is thoroughly characterized prior to attempting to manipulate its pluripotency. This commentary assesses the data generated to date and critically discusses the conclusions that have been drawn. Our current level of understanding, or lack of understanding, of the keratinocyte stem cell is reviewed.
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Affiliation(s)
- Christopher S Potten
- Epithelial Biology Department, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, U.K.
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39
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Abstract
The telomere is a special functional complex at the end of linear eukaryotic chromosomes, consisting of tandem repeat DNA sequences and associated proteins. It is essential for maintaining the integrity and stability of linear eukaryotic genomes. Telomere length regulation and maintenance contribute to normal human cellular aging and human diseases. The synthesis of telomeres is mainly achieved by the cellular reverse transcriptase telomerase, an RNA-dependent DNA polymerase that adds telomeric DNA to telomeres. Expression of telomerase is usually required for cell immortalization and long-term tumor growth. In humans, telomerase activity is tightly regulated during development and oncogenesis. The modulation of telomerase activity may therefore have important implications in antiaging and anticancer therapy. This review describes the currently known components of the telomerase complex and attempts to provide an update on the molecular mechanisms of human telomerase regulation.
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Affiliation(s)
- Yu-Sheng Cong
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9039, USA.
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40
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Lee CJ, Suh EJ, Kang HT, Im JS, Um SJ, Park JS, Hwang ES. Induction of senescence-like state and suppression of telomerase activity through inhibition of HPV E6/E7 gene expression in cells immortalized by HPV16 DNA. Exp Cell Res 2002; 277:173-82. [PMID: 12083799 DOI: 10.1006/excr.2002.5554] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The E6 and E7 oncoproteins of human papillomavirus (HPV) play a major role in the development of cervical carcinoma. In this study, a recombinant adenovirus that expresses the bovine papillomavirus (BPV) E2, which has been shown to inhibit HPV early gene expression, was delivered to two HPV-immortalized cell lines as well as CaSki, a cervical carcinoma cell line. We tested whether the carcinoma and the immortal cells were equally affected by the expression of BPV E2. In all cell lines, BPV E2-mediated inhibition of HPV E6/E7 expression caused a dramatic suppression of cell growth, being preceded by the activation of the p53-Rb growth-inhibitory pathway, and a decrease in hTERT mRNA expression and telomerase activity. This suggests that the HPV E6 and E7 proteins are required not only for induction of the proliferative phenotype and telomerase activity, but also for their maintenance. In both the carcinoma and the immortal lines, the number of cells with enlarged cytoplasm and senescence-associated beta-galactosidase activity, which are markers for cellular senescence, was significantly increased. These results suggest that a senescence program exists in cells immortalized by HPV DNA as well as in cervical carcinoma cells.
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Affiliation(s)
- Chan Jae Lee
- Department of Life Science, University of Seoul, 90 Jeonnongdong, Dongdaemungu, Korea
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41
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Simbulan-Rosenthal CM, Velena A, Veldman T, Schlegel R, Rosenthal DS. HPV-16 E6/7 immortalization sensitizes human keratinocytes to ultraviolet B by altering the pathway from caspase-8 to caspase-9-dependent apoptosis. J Biol Chem 2002; 277:24709-16. [PMID: 11976323 DOI: 10.1074/jbc.m200281200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UVB from solar radiation is both an initiating and promoting agent for skin cancer. We have found that primary human keratinocytes undergo an apoptotic response to UVB. To determine whether these responses are altered during the course of immortalization, we examined markers of apoptosis in primary human foreskin keratinocytes (HFK) transduced with either a retroviral vector expressing the E6 and E7 genes of HPV-16 or with empty vector alone (LXSN-HFK). Whereas LXSN-HFK as well as early passage keratinocytes expressing HPV-16 E6 and E7 (p7 E6/7-HFK) were both moderately responsive to UVB irradiation, late passage-immortalized keratinocytes (p27 E6/7-HFK) were exquisitely sensitive to UVB-induced apoptosis. After exposure to UVB, enhanced annexin V-positivity and internucleosomal DNA fragmentation were observed in p27 E6/7-HFK compared with either LXSN- or p7 E6/7-HFK. Caspase-3 fluorometric activity assays as well as immunoblot analysis with antibodies to caspase-3 and poly(ADP-ribose) polymerase revealed elevated caspase-3 activity and processing at lower UVB doses in p27 E6/7-HFK compared with LXSN- or p7 E6/7-HFK. In addition, the caspase inhibitor DEVD-CHO reduced the apoptotic response and increased survival of all three HFK types. Immunoblot analysis revealed that caspase-8 was activated in all three cell types, but caspase-9 was only activated in p27 E6/7-HFK. Cell cycle analysis further showed that only p27 E6/7-HFK exhibit G(2)/M accumulation that is enhanced by UVB treatment. This accumulation was associated with a rapid down-regulation of Bcl-2 in these cells. The immortalization process subsequent to the expression of HPV E6 and E7 may therefore determine UVB sensitivity by switching the mode of apoptosis from a caspase-8 to a Bcl-2-caspase-9-mediated pathway of apoptosis.
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Affiliation(s)
- Cynthia M Simbulan-Rosenthal
- Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC 20007, USA
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42
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Steenbergen RDM, OudeEngberink VE, Kramer D, Schrijnemakers HFJ, Verheijen RHM, Meijer CJLM, Snijders PJF. Down-regulation of GATA-3 expression during human papillomavirus-mediated immortalization and cervical carcinogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:1945-51. [PMID: 12057898 PMCID: PMC1850837 DOI: 10.1016/s0002-9440(10)61143-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
To identify cellular genes that may be involved in human papillomavirus (HPV)-mediated immortalization mRNA differential display analysis was performed on preimmortal and subsequent immortal stages of four human keratinocyte cell lines transformed by HPV type 16 or 18 DNA. This yielded a cDNA fragment encoding the transcription factor GATA-3 that was strongly reduced in intensity in all immortal stages of the four cell lines. A marked reduction in both GATA-3 mRNA and protein expression in HPV-immortalized cell lines was confirmed by reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry and was also shown to be apparent in cervical carcinoma cell lines. Immunohistochemical analysis of cervical tissue specimens showed a clear nuclear staining for GATA-3 in normal cervical squamous epithelium (n = 14) and all cervical intraepithelial neoplasia (CIN) I (n = 6) and CIN II lesions (n = 2). In contrast, 11% (1 of 9) of CIN III lesions and 67% (8 of 12) of cervical squamous cell carcinomas revealed a complete absence of GATA-3 immunostaining. Hence, complete down-regulation of GATA-3 expression represents a rather late event during cervical carcinogenesis. Whether GATA-3 down-regulation is etiologically involved in HPV-mediated immortalization and cervical carcinogenesis remains to be examined.
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Affiliation(s)
- Renske D M Steenbergen
- Department of Pathology, Unit of Molecular Pathology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
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43
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Abstract
Cellular senescence or replicative senescence is a state of irreversible growth arrest that somatic cells enter as a result of replicative exhaustion. This can be mimicked by culture manipulations such as Ras oncogene overexpression or treatment with various agents such as sodium butyrate and 5-azacytidine. It is believed that cellular senescence is one of the protective mechanisms against tumor formation. Genetic analyses of cellular senescence have revealed that it is dominant over immortality because whole cell fusion of normal with immortal cells yields hybrids with limited division potential. Only four complementation groups for indefinite division have been identified from extensive studies fusing different immortal human cell lines with each other. The senescence-related genes for three of the complementation groups B-D have been identified on human chromosomes 4, 1, and 7, respectively, by microcell-mediated chromosome transfer, though the existence of senescence-related genes on other chromosomes has been suggested. MORF4 was cloned as the senescence-related gene on human chromosome 4 and is a member of a new gene family, which has multiple transcription factor-like motifs. This gene family may affect cell division by modulating gene expression. Study of this novel gene family should lead to new insights regarding the mechanisms and function of cellular senescence in aging and immortalization.
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Affiliation(s)
- Kaoru Tominaga
- Sam and Ann Barshop Center for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, STCBM, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
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44
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Bosch FX, Lorincz A, Muñoz N, Meijer CJLM, Shah KV. The causal relation between human papillomavirus and cervical cancer. J Clin Pathol 2002; 55:244-65. [PMID: 11919208 PMCID: PMC1769629 DOI: 10.1136/jcp.55.4.244] [Citation(s) in RCA: 2214] [Impact Index Per Article: 100.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2002] [Indexed: 02/06/2023]
Abstract
The causal role of human papillomavirus infections in cervical cancer has been documented beyond reasonable doubt. The association is present in virtually all cervical cancer cases worldwide. It is the right time for medical societies and public health regulators to consider this evidence and to define its preventive and clinical implications. A comprehensive review of key studies and results is presented.
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Affiliation(s)
- F X Bosch
- Institut Català d'Oncologia, Servei d'Epidemiologia i Registre del Càncer, Gran Via Km 2.7 s/n 08907 L'Hospitalet de Llobregat, 08907 Barcelona, Spain.
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45
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Ducrest AL, Szutorisz H, Lingner J, Nabholz M. Regulation of the human telomerase reverse transcriptase gene. Oncogene 2002; 21:541-52. [PMID: 11850779 DOI: 10.1038/sj.onc.1205081] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Most somatic human cells lack telomerase activity because they do not express the telomerase reverse transcriptase (hTERT) gene. Conversely, most cancer cells express hTERT and are telomerase positive. For most tumors it is not clear whether hTERT expression is due to their origin from telomerase positive stem cells or to reactivation of the gene during tumorigenesis. Telomerase negative cells lack detectable cytoplasmic and nuclear hTERT transcripts; in telomerase positive cells 0.2 to 6 mRNA molecules/cell can be detected. This suggests that expression is regulated by changes in the rate of hTERT gene transcription. In tumor cell lines hTERT expression behaves like a recessive trait, indicating that lack of expression in normal cells is due to one or several repressors. Studies with monochromosomal hybrids indicate that several chromosomes may code for such repressors. A number of transcription factors, tumor suppressors, cell cycle inhibitors, cell fate determining molecules, hormone receptors and viral proteins have been implicated in the control of hTERT expression; but these studies have not yet provided a clear explanation for the tumor specific expression of the hTERT gene, and the cis-acting elements which are the targets of repression in normal cells still have to be identified.
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Affiliation(s)
- Anne-Lyse Ducrest
- Swiss Institute for Experimental Cancer Research (ISREC), CH-1066 Epalinges, Switzerland
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46
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Keith WN, Jeffry Evans TR, Glasspool RM. Telomerase and cancer: time to move from a promising target to a clinical reality. J Pathol 2001; 195:404-14. [PMID: 11745671 DOI: 10.1002/path.1001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The past 25 years have seen unparalleled advances in our understanding of the molecular basis of cancer. As a result, novel molecular targets have been identified that provide great potential for the development of new cancer diagnostics and therapies. Four key features of cancer cells distinguish them from their normal counterparts: loss of cell-cycle regulation, loss of control over invasion and metastasis, failure of apoptotic mechanisms, and bypass of senescence. This review examines our understanding of the bypass of senescence and the process of immortalization during carcinogenesis. In addition, the realistic opportunities for telomerase in cancer diagnostics and the challenges faced in clinical trial design for telomerase therapeutics are discussed.
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Affiliation(s)
- W N Keith
- CRC Department of Medical Oncology, University of Glasgow, CRC Beatson Laboratories, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK.
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