The methylation status of 23 genes that were previously reported associated with various epithelial malignancies was assessed in normal and abnormal ovarian tissues by methylation-specific PCR. The presence of p53 mutation (n = 82 cases) and Her-2/neu overexpression (n = 51 cases) were assessed by DNA sequencing and immunohistochemistry, respectively.
Methylation of four genes (MINT31, HIC1, RASSF1, and CABIN1) was significantly associated with ovarian cancer but not other ovarian pathology. Her-2/neu overexpression was associated with aberrant methylation of three genes (MINT31, RASSF1, and CDH13), although aberrant methylation was not associated with p53 mutations. Methylation of RASSF1 and HIC1 was more frequent in early compared to late stage ovarian cancer, while methylation of CABIN1 and RASSF1 was associated with response to chemotherapy.
DNA methylation of tumor suppressor genes is a frequent event in ovarian cancer, and in some cases is associated with Her-2/neu overexpression. Methylation of CABIN1 and RASSF1 may have the utility to predict response to therapy.