OBJECTIVETo investigate the expression of OPCML gene in ovarian epithelial carcinoma and determine the relationship between mRNA expression and methylation of their promoters.

METHODTwenty normal ovarian tissues and 89 ovarian epithelial tumor specimens (72 malignant, 17 benign), as well as 3 ovarian carcinoma cell lines (SKOV-3, CAOV3, and 3AO), were collected for detection of OPCML gene expression by reverse transcription-polymerase chain reaction and for detection of promoter methylation by restriction enzyme cut analysis from 7. 1999 to 7. 2003.

RESULTSAmong ovarian epithelial carcinoma 19.4% expressed OPCML mRNA, while 85% of normal ovarian tissue and 76.5% of benign ovarian tumor. The ratio of expression of OPCML mRNA in ovarian epithelial carcinoma was significantly lower than those of normal (chi2 = 30.108, P = 0.0000) and benign tumors (chi2 = 21.162, P = 0.000). No OPCML mRNA expression was found in SKOV-3 and CAOV3, but was found in 3AO. Methylations were detected in 44.4% of cancer cells promoter, while 0% in normal ovarian tissue and benign ovarian tumors. The ratio of methylation of ovarian epithelial carcinoma was significantly higher than those of normal (chi2 = 13.630, P = 0.0000) and benign tumors (chi2 = 11.797, P = 0.000). Methylation was found in SKOV-3 and CAOV3, but not in 3AO. The relationship between gene expression and promoter methylation was correlated (r = 11.589, P = 0.002), especially at Hap I1 site (r = 11.640, P = 0.004). Methylation was also found in SKOV-3 and CAOV3 cell lines, but not in 3AO cell line.

CONCLUSIONDeletion of OPCML gene exists in ovarian epithelial carcinoma cell. The gene promoter methylations, especially Hap II motif, may be one of pathways that contribute the inhibition of OPCML expression.