Inhibition of Tumor Growth, Steroidogenesis, Hormone and Drugs Resistance by an Acyl-CoA Synthetase 4 New Inhibitor

CASTILLO AF.; ORLANDO U.; PRADA J.; DATTILO MA; SOLANO ANGELA; SZAJNMAN S; LORENZANO MENNA P; GOMEZ DE; RODRIGUEZ JB; PODESTÁ EJ

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

Acyl-CoA synthetase 4 (ACSL4) is an isoenzyme of the fatty acid ligase-coenzyme A ligase family taking part in arachidonic acid metabolism.This enzyme is involved in cancer development, particularly in breast and prostate cancers, where a correlation between its high expression andtumor cell aggressiveness has been found. Functionally, it was shown that ACSL4 is part of the mechanism responsible for increased breast andprostate cancer cell proliferation, invasion and migration. ACSL4 is involved in the regulation of several signal transduction mechanismsincluding mTOR pathway and furthermore increase the expression of proteins involved in drugs resistance. Another relevant property of thisenzyme is its participation as an essential protein in the activation of cholesterol transport from the external to the internal mitochondrialmembrane, the regulatory and rate-limiting step in the syntheses of all steroids. The development of selective inhibitors for ACSL4, which mayinhibit tumor growth and steroidogenesis, may be an important tool in the prevention and treatment of breast and prostate cancers expressingACSL4. In this work, we have developed and characterized a new ACSL4 inhibitor, PRGL493. An ACSL4 homology model was generated byMODELLER and a docking based virtual screening was performed. The selected compound was modified to improve particularly solubilityproperties and fully characterized through nuclear magnetic resonance and mass spectroscopy. We demonstrated that PRGL493 was effective inreducing AA-CoA levels, product of ACSL4 activity, in a cell free assay system using recombinant protein and in intact cells using cells modelsfor steroidogenesis and tumor growth. Our compound inhibited cell proliferation and migration of highly aggressive human breast and prostatecancer cell lines (MDA-MB-231 and PC-3 respectively) and in vivo using the Chick Embryo Chorioallantoic Membrane model assay. Inaddition, PRGL493 inhibited steroid synthesis both in vitro in Leydig, adrenal and PC-3 prostate cancer cells and in vivo in a mouse model,inhibiting cholesterol transport o the inner mitochondrial membrane and thus preventing steroid accumulation. Moreover, the inhibitor producedsensitization to hormonal and chemotherapeutic treatment. The combination of PRGL493 with tamoxifen, cisplatin, doxorubicin or paclitaxel inMDA-MB-231 cells, or with docetaxel in PC-3 cells showed a synergistic effect on the inhibition of cell proliferation. The results show thatACSL4 is an essential target for breast and prostate cancer therapy. These findings open an important route to treat these tumors that may lead tothe development of rational cancer treatment and continue to lead to the introduction of the combination of chemotherapy to specific otheragents.