Loss of OPCML expression and the correlation with CpG island methylation and LOH in ovarian serous carcinoma.

To detect the expression of OPCML in ovarian serous carcinoma and investigate the correlation with CpG island methylation and LOH of OPCML. 20 normal tissues, 75 ovarian serous tumors, three cell lines, SKOV-3, CAOV3 and 3AO, were detected in OPCML expression by RT-PCR, CpG island methylation by methylation-sensitive restriction enzyme-PCR, and LOH analysis at four microsatellite marks (D11S4085, D11S1320, D11S874 and D11S969). Loss of OPCML expression in ovarian serous carcinomas was significantly higher than in ovarian adenomas and normal tissues. OPCML expression was detectable in 3AO, but not in SKOV-3 and CAOV3. CpG island methylation was found in 53.4% of the carcinomas, while in none of the adenomas or normal tissues. Meanwhile, CpG island methylation was detectable in SKOV-3 and CAOV3, but not in 3AO. The correlation between CpG island methylation and loss of OPCML expression was found in carcinomas. The LOH rate at D11S4085 in carcinomas was significantly higher than that for adenomas and normal tissues. LOH at D11S4085 was also correlated with loss of OPCML expression. These results indicate that loss of OPCML expression occurs frequently in ovarian serous carcinoma. CpG island methylation and LOH are probably two mechanisms of OPCML inactivation.