p73 gene expression in ovarian cancer tissues and cell lines

The p73 gene, a homology of p53, is a new candidate of imprinting and tumor suppressor gene, To investigate the role of p73 in ovarian cancer, we stud ied the allelic expression in 56 cases of ovarian cancer using StyI polymor phism analysis. We also examined p73 expression by semi-quantitative revers e transcription-PCR as well as by Western blot analysis and DNA methylation study of the CpG island in exon 1 in ovarian cancer tissues and cell lines , Loss of heterozygosity was found in 8.3% (2 of 24) of the cases, Bialleli c expression was demonstrated in 91.7% (22 of 24) of the tumor samples, in 70.8% (17 of 2$) of the normal samples, and in 1 ovarian cancer cell line. Imbalanced expression and monoallelic expression were found in three and tw o pairs of matched samples, respectively, Overexpression of p73 was found i n advanced ovarian cancer rather than in early-stage disease or in borderli ne ovarian tumor. No significant difference was found in the p53 expression . Three cell lines with absent p73 protein expression and one tumor sample with monoallelic expression were methylated in the CpG island, Demethylatio n in SKOV3 cell line using 5-azacytidine can reactivate the expression of t his gene in both the mRNA and the protein level, Our results indicated that p73 was not imprinted in most of the ovarian cancer and normal tissues, bu t it could be involved in the advanced ovarian cancer through overexpressio n, DNA methylation mag. contribute to the lack of p73 expression.