RESUMO
Prostate cancer (PC) is one of the leading causes of cancerrelated death in the male population worldwide. Mortality of PC is dependent on tumor recurrence and its progression to metastatic disease. We examined the effects of pentacyclic triterpene pomolic acid (PA) on docetaxelresistant PC3 cells. Cell viability was evaluated using the MTT assay. Apoptosis was evaluated by cell cycle analysis using flow cytometry. The activity of multiple drug resistance (MDR) proteins was determined by the accumulation of specific substrates [mitoxantrone, rhodamine 123 and 5carboxyfluorescein diacetate (CFDA)]. The evaluation of epithelial to mesenchymal transition (EMT) proteins was conducted by immunocytochemical assays. It was demonstrated that PC3R cells presents multidrug resistance and EMT phenotype and express active Pgp/ABCB1 and MRP1/ABCC1. It was shown that PA strongly reduced the viability and induced apoptosis of both PC3 and PC3R cell lines. Moreover, PA bypassed Pgp/ABCB1, downmodulated MRP1/ABCC1 activities, and partially reverted EMT induced by DTX. Our goal was to evaluate the potential of PA for the development of novel strategies to treat castrationresistant PC.