Purchase this article with an account.
A.P. Moulin, G. Clement, F.T. Bosman, L. Zografos, J. Benhattar; Patterns of promoter hypermethylation in uveal melanoma . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1069.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Inactivation of tumor suppressor genes by promoter hypermethylation appears to be a common epigenetic finding in the development of many tumors. In this study, we investigated in primary uveal melanoma the status of promoter methylation of genes commonly thought to be involved in tumor development such as p16, hTERT, TIMP3, RARb2, FHIT, and APC. Only p16 promoter methylation has been previously evaluated in primary uveal melanomas, as well as in cutaneous melanomas. Methods:Twenty formalin–paraffin–embedded primary uveal melanoma were studied. DNA was extracted from tissue sections and subsequently treated with sodium bisulfite that allows the conversion of cytosine residues into uracil unless a methyl group at the cytosine residue prevents deamination by bisulfite. DNA was subsequently amplified by PCR using primers without CpG sites to avoid selective amplification of either methylated or unmethylated DNA. Promoter methylation was investigated through quantitative methylation sensitive single–strand conformation analysis. Results: Analysis of the methylation status of p16, TIMP3, hTERT, RARb2, and FHIT promoters, yielded only one case with 100% methylation for each of these genes. In these cases, all the tumor cells showed methylation of both alleles of all of these gene promoters. In one case that was investigated for the FHIT promoter, 20 % methylation was found, implying that only a small percentage of tumor cells had this alteration. The analysis of the APC promoter demonstrated in one case 50 % methylation. This finding can be either interpreted in terms of heterogeneity of the tumor cell population or as methylation of only one of the two APC alleles. Only one tumor shared hypermethylation of two gene promoters, RARb2 and APC. Conclusions: For all the genes studied, promoter hypermethylation was found in 10% or less of primary uveal melanomas. Thus, promoter hypermethylation of genes frequently involved in tumor development does not seem to be a common mechanism involved in the development of uveal melanoma. The analysis of P16 gene promoter methylation yielded findings quite similar to those of previous studies in uveal melanoma and in cutaneous melanoma, suggesting that in the tumorigenesis of these tumors common epigenetic mechanisms are involved.
This PDF is available to Subscribers Only