Analysis of aberrant methylation of the VHL gene by transgenes, monochromosome transfer, and cell fusion

Citation
I. Kuzmin et al., Analysis of aberrant methylation of the VHL gene by transgenes, monochromosome transfer, and cell fusion, ONCOGENE, 18(41), 1999, pp. 5672-5679
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Onconogenesis & Cancer Research
Journal title
ONCOGENE
ISSN journal
0950-9232 → ACNP
Volume
18
Issue
41
Year of publication
1999
Pages
5672 - 5679
Database
ISI
SICI code
0950-9232(19991007)18:41<5672:AOAMOT>2.0.ZU;2-I
Abstract
Several tumor suppressor genes were shown to be inactivated by a process in volving aberrant de novo methylation of their GC-rich promoters which is us ually associated with transcriptional repression, The mechanisms underlying this process are poorly understood. In particular this abnormal methylatio n may be caused and/or maintained by either deficiency of some tl ails-acti ng factor(s) or by various malfunctions acting in cis, Here we studied the nature of aberrant methylation of the ron Hippel-Lindau (VHL) disease tumor suppressor gene in a human clear cell renal carcinoma cell line, UOK 121, that contains a silent hypermethylated endogenous VHL allele, First, we tra nsfected unmethylated VHL transgenes, driven by the VHL promoter, into UOK 121 cells. Next, to exclude possible position effects that may influence me thylation of the introduced VHL genes, we transferred a single chromosome 3 , carrying an apparently normal hypomethylated VHL allele into the UOK 121 cells. Finally, ne created somatic cell hybrids between UOK 121 and UMRC 6 cells containing a mutant VHL-expressing hypomethylated allele, In these th ree experiments both the methylation of the VHL promoter and the transcript ional status of the introduced and endogenous VHL alleles remained unchange d. Our results demonstrate that the putative tr ans-acting factors present in the UOK 121 and UMRC 6 cells are unable to induce changes in methylation pattern of the VHL alleles in all cell lines and hybrids studied. Taken to gether, the results indicate that ris-specific local features are pivotal i n maintaining and perpetuating aberrant methylation of the VHL CpG island. Contribution of some putative tr ans-acting factors cannot be excluded duri ng a period when the aberrant VHL methylation pattern was first generated.