We recently reported that of seven genes frequently methylated in epithelial tumors, only RASSF1A gene was frequently methylated in mesotheliomas, and its methylation was correlated with loss of RASSF1A expression and the presence of SV40.
These data, together with our previous findings, support a causal relationship between SV40 infection, progressive RASSF1A methylation and its silencing, and the pathogenesis of mesothelioma.
Our major findings are: (a) with the exception of the RASSF1A promoter of the RASSF1 gene, frequencies of aberrant methylation were significantly lower in MMs than in adenocarcinomas; (b) the frequency of RASSF1A aberrant methylation and the value of the methylation index were significantly higher in SV40 sequence positive MM than in negative MM; and (c) the methylation index was higher in epithelial MM than in sarcomatous/mixed MM.