In addition, as previously observed, LNCaP inhibitor Vismodegib cells were those depicting the lowest methylation levels. Fur thermore, and except for PC3 in which a slightly signifi cant decrease in methylation levels was detected after treatment with DAC alone or combined with TSA, no significant effects were found in methylation levels compared Inhibitors,Modulators,Libraries to mock cells in PCa cell lines, in line with bi sulfite sequencing analysis results. Nevertheless, MDR1 expression levels increased in all cancer cell lines after treatment with epigenetic modulating H4Ac at the MDR1 gene promoter was found, after ex posure to TSA alone or in combination with DAC, com pared to untreated cells. The active marks fold variation differed among the treatments and respective cell lines, in accordance with the above mentioned re expression data, excluding PC3.

Whereas in LNCaP cells TSA exposure induced an impressive increase in the accu st, 0. 001 p 0. 015. Interestingly, re expression levels were Inhibitors,Modulators,Libraries significantly higher when DAC and TSA were Inhibitors,Modulators,Libraries used in combination, in all cell lines except for LNCaP, in which TSA alone in duced the most impressive enhancement in MDR1 tran script levels. Effect of epigenetic modulating drugs on activating histone marks at the MDR1 promoter in PCa cell lines Because histone post translational modifications are also associated with gene transcription activation/repression status, ChIP analysis was carried out for the native MDR1 promoter in LNCaP, DU145 and PC3 cell lines, after treat ment with TSA alone or combined with DAC.

Moreover, since the effect in MDR1 re expression of DAC alone was modest, the histone marks were not assessed for this treat ment regimen. Interestingly, for all cell lines, enrichment in histone ac tivating marks or in Inhibitors,Modulators,Libraries combination with DAC. Discussion The P glycoprotein, encoded by the MDR1/ABCB1 gene, is a transmembrane protein involved in ATP dependent transport of specific substrates across lipid membranes, playing an important role in steroid Inhibitors,Modulators,Libraries metabolism and in the export of metabolites, carcinogens and cytotoxic drugs such as anthracyclines, taxanes, vinca alkaloids and epipo dophyllotoxins. Although several mutations in this transporter have been associated with human disease, the actual consequences in its function are still controversial. In PCa, MDR1 is frequently methylated at its promoter region compared to non tumorous prostate tissues and has thus been proposed as a PCa biomarker. Al though a few studies have correlated MDR1 promoter methylation with decreased transcription the following site in PCa, the biologic impact of this epigenetic alteration and its role in prostate carcinogenesis has not been fully elucidated.