Extinction of reaction product was measured at 405 nm on Victor3 1420 Multilabel Counter reader. Amounts of generated aPC were calculated using aPC standards and normal ized to cell protein content. Data analysis Data were analyzed by one way analysis of variance coupled with Dunnetts post hoc test to compare each experimental group with a nominated most control group using SPSS 14. 0 software. Differences were considered significant at P 0. 05. Background Epithelial ovarian cancer is the fifth leading cause of cancer death in women and the most lethal gynecolo gic malignancy. In spite of aggressive surgical cytore duction and combination platinum paclitaxel chemotherapy, over 75% of women with stage III IV dis ease will relapse and succumb to their disease.

Resis tance to platinum based therapy is a primary obstacle in the management of advanced OC and novel therapies are required to enhance platinum chemotherapy and to improve prognosis. Hereditary mutations in the Breast Cancer 1 tumor suppressor gene are associated with a significant risk of developing breast and OC. Although somatic mutations in BRCA1 are uncommon in sporadic OC, BRCA1 dysfunction is frequently observed. Silencing of BRCA1, through promoter methylation, decreased expression through gene deletion, or dysregulation of related genes in the Fanconi anemia BRCA1 pathway, is believed to be important in the pathogenesis of a significant proportion of sporadic tumors. Preclinical work has shown that the level of BRCA1 protein expression correlates with chemosensitivity, and recent clinical data supports that BRCA1 deficient OC patients have a better prognosis.

Low BRCA1 protein and mRNA expression has also been associated with improved survival in breast cancer and non small cell lung cancer. The improved outcome in BRCA1 deficient tumors is believed to be due, in part, to an increased sensitivity to DNA damaging che motherapeutics, such as cisplatin. Cells that lack BRCA1 have a deficiency in the repair of double strand breaks by the conservative mechanism of homologous recombination. As a result, these cancer cells are reduced to using error prone pathways thereby lead ing to genomic instability and enhanced cisplatin cyto toxicity. Thus, BRCA1 has been regarded as a rational therapeutic target to help overcome platinum resistance in advanced and recurrent OC.

However, in an era of evolving molecular inhibitors, new therapeutic strategies merit consideration. The interaction between histone acetyl transferases and histone deacetylase enzymes modulates chromatin structure and transcription factor accessibil ity, resulting Brefeldin_A in changes in gene expression. Inhibi tors of HDAC have pleiotropic effects on cell cycle arrest, apoptosis, differentiation and inhibition of growth and angiogenesis, and have emerged as promis ing new therapeutic agents in multiple cancers, includ ing those resistant to standard chemotherapy.