Objective: To evaluate the expression of p16INK4A gene in ovarian cancer and analyze the relation between this alteration and the promoter methylation of p16INK4A DNA.
Methods: The expression of p16INK4A mRNA was detected with RT-PCR in ovarian cancer cell lines and tissues, and the protein was detected by western blot. Methylation specific PCR (MSP) was used to check whether it was methylated in the promoter of p16INK4A, and normal ovarian tissues were used as control. The demethylating agent, 5-aza-2'-deoxycytidine, was used to treat methylated ovarian cancer cells and then, ovarian cancer cell growth was measured in vivo and in vitro.
Results: Three ovarian cancer cell lines (Anglne, SW626, OVCAR3) and six ovarian cancer specimens were found methylated in p16INK4A DNA; the methylation rate was 3/7 and 33% (6/18) in ovarian cancer cell lines and specimens respectively. All the methylated cell lines and ovarian cancer tissues expressed decreasing p16INK4A mRNA and protein. Compared with the control, both the expression of p16INK4A mRNA and protein were decreased significantly or absolutely deleted in ovarian cancer cells (P < 0.05). The decrease was partly due to the methylation of p16INK4A. 5-aza-2'-deoxycytidine could reactivate the expression of p16INK4A in methylated cells and decrease the cell growth in vivo and in vitro.
Conclusion: The disfigurement of p16INK4A gene plays an important role in the development of ovarian cancer, and this alteration is partially caused by methylation of p16INK4A DNA.