DNA Methylation and microRNA patterns are in association with the expression of BRCA1 in ovarian cancer

Ovarian cancer is the sixth most prevalent cancer in women and is considered the most lethal gynecological malignancy. It can be inherited as a familial disease but also has a strong spontaneous occurrence. Although the disease is associated with genome instability brought on by genetics and environmental factors there is evidence that mutations in the gene encoding for the breast cancer type 1 susceptibility protein (BRCA1) or its down-regulation are involved in its development. Down-regulation of BRCA1 expression by hypermethylation of its promoter may account for some cases of ovarian cancer but this does not explain the cause of the majority of the disease. This review explores the role of BRCA1 promoter hypermethylation and micro-RNAs (miRNA) involved in the regulation of BRCA1 and their role in ovarian cancer development as well as some of the exciting discoveries which could lead to targeting miRNA with a view to restoring BRCA1 expression in diseased tissues.

The apoptotic effects of sirtuin1 inhibitor on the MCF-7 and MRC-5 cell lines

Sirtuin1 (SIRT1) is an enzyme that deacetylates histones and several nonhistone proteins including p53 during stress and plays an important role in the survival of tumor cells. Hereby, this study describes the potency of salermide as a SIRT1 inhibitor to induce apoptosis in the MCF-7 and MRC-5 cell lines. MCF7 and MRC-5 cell lines were cultured in RPMI-1640 and treated with or without salermide at concentration of 80.56 μmol/L, based on the half-maximal inhibitory concentration (IC50) index at different times (24, 48 and72 h). The IC50 value was established for the salermide in MCF-7. The percentage of apoptotic cells was measured by flow cytometry. Real-time quantitative RT-PCR was performed to estimate the mRNA expression of sirtuin1 in MCF-7 and MRC-5 with salermide at different times. ELISA and Bradford protein techniques were used to detect endogenous levels of total and acetylated p53 protein generated in MCF-7 and MRC-5 cells. Our findings indicated that salermide can induce apoptosis in MCF-7 significantly more effective than MRC-5 cells. We showed that the expression of SIRT1 was dramatically down-regulated by increasing the time of salermide treatment in MCF-7 but not MRC-5 and that the acetylated and total p53 protein levels were increased more in MCF-7 than MRC-5. Salermide, by decreasing the expression of sirtuin1 gene, can induce acetylation of P53 protein and consequently induce significant cell death in MCF-7 that was well tolerated in MRC-5.