Acyl-CoA synthetase 4 (ACSL4) is an isoenzyme of the fatty acid ligase-coenzyme-A family taking part in arachidonic acid metabolism and steroidogenesis. ACSL4 is involved in the development of tumor aggressiveness in breast and prostate tumors through the regulation of various signal transduction pathways. Here, a bioinformatics analysis shows that the ACSL4 gene expression and proteomic signatures obtained using a cell model was also observed in tumor samples from breast and cancer patients. A well-validated ACSL4 inhibitor, however, has not been reported hindering the full exploration of this promising target and its therapeutic application on cancer and steroidogenesis inhibition. In this study, ACSL4 inhibitor PRGL493 was identified using a homology model for ACSL4 and docking based virtual screening. PRGL493 was then chemically characterized through nuclear magnetic resonance and mass spectroscopy. The inhibitory activity was demonstrated through the inhibition of arachidonic acid transformation into arachidonoyl-CoA using the recombinant enzyme and cellular models. The compound blocked cell proliferation and tumor growth in both breast and prostate cellular and animal models and sensitized tumor cells to chemotherapeutic and hormonal treatment. Moreover, PGRL493 inhibited de novo steroid synthesis in testis and adrenal cells, in a mouse model and in prostate tumor cells. This work provides proof of concept for the potential application of PGRL493 in clinical practice. Also, these findings may prove key to therapies aiming at the control of tumor growth and drug resistance in tumors which express ACSL4 and depend on steroid synthesis.

酰基辅酶A合成酶4（ACSL4）是参与花生四烯酸代谢和类固醇生成的脂肪酸连接酶辅酶A家族的同工酶。ACSL4通过调节各种信号转导途径参与乳腺癌和前列腺肿瘤的侵袭性发展。在此，生物信息学分析表明，在乳腺癌和癌症患者的肿瘤样本中也观察到了使用细胞模型获得的ACSL4基因表达和蛋白质组学特征。然而，尚未报导一种经过验证的ACSL4抑制剂会妨碍对该有希望的靶标的全面探索及其对癌症和类固醇生成抑制的治疗应用。在这项研究中，使用ACSL4同源模型和基于对接的虚拟筛选鉴定了ACSL4抑制剂PRGL493。然后通过核磁共振和质谱对PRGL493进行化学表征。通过使用重组酶和细胞模型抑制花生四烯酸转化成花生四烯酰辅酶A，证明了其抑制活性。该化合物在乳腺癌和前列腺细胞及动物模型中均能阻止细胞增殖和肿瘤生长，并使肿瘤细胞对化学疗法和激素疗法敏感。此外，PGRL493在小鼠模型和前列腺肿瘤细胞中抑制了睾丸和肾上腺细胞中从头类固醇的合成。这项工作为PGRL493在临床实践中的潜在应用提供了概念验证。同样，这些发现可能证明是用于控制表达ACSL4并依赖类固醇合成的肿瘤中的肿瘤生长和耐药性的疗法的关键。