ROLE OF ACYL-COA SYNTHETASE 4 IN PROSTATE CANCER CELLS

PRADA, J.G.; PODESTÁ, E.J.; ORLANDO, U.; MALOBERTI, P.M.; SOLANO, A.R.; CASTILLO, A.F.

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Sociedad Argentina de Investigaciones Bioquímica y de Biología Molecular (SAIB)

Acyl-CoA synthetase-4 (ACSL4) is an enzyme taking part in arachidonic acid metabolism. The expression of ACSL4 has been shown to be associated with aggressiveness of several types of cancer such as colon and hepatocellular carcinoma. ACSL4 is part of the mechanism responsible of the aggressiveness in breast and prostate cancer cells, being increased in malignant cells, particularly in castration-resistant prostate cancer (CRPC). It plays a key role in the regulation of cell growth by controlling upstream effectors of mTOR pathway in breast cancer cells. In addition, ACSL4 participates in steroid synthesis through of arachidonic acid release and induction of Steroidogenic Acute Regulatory protein (StAR). The aim of this work was to analyze the effect of ACSL4 inhibition in prostate cancer cells on steroidogenesis and signaling pathway regulated by this enzyme. Also we charactherized the effect of PRGL493 in prostate cells, the specific ACSL4 inhibitor recently developed in our lab. PC3 prostate cancer cell line treatment with PRGL493 produced a significant cell proliferation inhibition and migration measured by BrdU incorporation assay and wound healing assay. Moreover, combination of sub-maximal doses of PGRL493 (5μM) and of docetaxel (1nM), a chemotherapeutic drug, generated a synergistic effect on inhibiting cell proliferation. It is known that androgen receptor (AR) expression and ACSL4 levels are inversely correlated in human prostate tumors, being associated a high ACSL4 expression with loss of steroid hormones sensitivity. After ACSL4 inhibition with PRGL493 we could detect an increase in AR mRNA levels in PC3 cell line through real time PCR. Aggressive prostate tumors are able to synthesize steroids, and even in low amounts are very important in tumor biology and in its malignant behavior. ACSL4 inhibition in PC3 produced a decrease in steroid levels detected by radioimmunoassay. Also, a decrease in StAR protein expression, the key steroidogenesis protein involved in the limiting step of steroids production, was detected.Then, we evaluated the role of ACSL4 on mTOR pathway regulation in prostate cancer cells. We analized the expression of different proteins such as pS6, pGSK3αβ, pRICTOR and pAKT by Western Blot, finding a decrease in their expression after treatment with PRGL493. These results all together contribute to show the effect of ACSL4 and its new developed inhibitor on steroidogenesis, mTOR pathway, migration and proliferation in prostate cancer cells, supporting the relevance of targeting ACSL4 in prostate cancer treatments, especially in CRPC, aggressive hormone independent tumor for which there is no fully effective treatment.