Simvastatin Induces Autophagy and Inhibits Proliferation in Prostate Cancer Cells

Abstract

Background/Aim: Statin has recently been studied for its effects on inducing cell death and inhibiting metastasis. Nevertheless, the precise mechanism of its anti-tumor effect is not yet fully understood. We conducted research on statin as a novel treatment for castration-resistant prostate cancer (CRPC). This study focused on autophagy in prostate cancer cells and assessed the effects of simvastatin. Materials and Methods: After administering simvastatin to PC-3 cells, we conducted a microarray analysis. Simvastatin was administered to prostate cancer cell lines (PC-3, LNCaP-LA; cultured under androgen-depleted conditions, DU145, 22RV1), and the tumor proliferation inhibition was evaluated using the MTS assay and cell count. Autophagy was measured by observing autophagosome staining under a fluorescence microscope and quantifying LC-3 protein using western blot. We also investigated the effects of rapamycin, an autophagy inducer, and chloroquine as an inhibitor. Results: Simvastatin demonstrated a significant concentration-dependent growth inhibition effect on prostate cell lines. Moreover, a significant increase in autophagy was observed in all cell lines following simvastatin administration. When we administered simvastatin with rapamycin at a concentration that did not show a tumor growth inhibitory effect, it significantly enhanced autophagy induction compared to simvastatin alone, and also significantly enhanced the growth inhibition effect on PC-3 cells. Conclusion: Simvastatin induced autophagy and inhibited the proliferation of prostate cancer cell lines. The combination of simvastatin and rapamycin significantly induced autophagy and enhanced the inhibitory effect of simvastatin on proliferation. This mechanism may serve as a novel therapeutic target.