Metformin and Flutamide Combination Therapy's Efficacy and Safety in Prostate Cancer Cell Lines

Considering the hepatotoxicity and other side effects associated with flutamide as a first-line treatment for prostate cancer (PCa), this study aimed to evaluate metformin as a potential anticancer agent to reduce the required dose of flutamide and thereby minimize its adverse effects.

We assessed the influence of metformin, flutamide, and metformin-flutamide combination therapy on LNCaP, DU145, and PC3 cell lines, which represent human PCa. The tests include wound-healing assay, colony formation assay (CFA), analysis of apoptosis (programmed cell death) and cell cycle by flow cytometry, gene expression at the mRNA level by real-time PCR (BAX/BCL2, E-cadherin, Snail, HIF1α, VEGFC, and KLK3 genes), and assessment of the treatments' hepatotoxicity potential via measuring AST and ALT values.

To determine the IC50 (half-maximal inhibitory concentration) values, cell lines were treated with different concentrations of the drugs. The IC50 values for metformin (800 μM) in the three cell lines and for flutamide (12 μM for PC3 and 10 μM for LNCaP/DU145), as determined by MTT assay, were confirmed by flow cytometry, indicating significant cell cycle arrest at the G0/G1 phase. The combination of metformin and flutamide significantly increased the BAX/BCL2 mRNA ratio in all three cell lines (p < 0.0001) and downregulated the expression of KLK3 (p < 0.01), HIF1α (p < 0.01), VEGFC (p < 0.001), and EMT pathway genes in PC3 and LNCaP (p < 0.01). Liver injury assessment reported a reduction in flutamide's hepatotoxicity in combination with metformin.

Metformin in combination with flutamide reduced its dose and increased the sensitivity of PCa cells to treatment. Additionally, it mitigated the hepatotoxic effects of flutamide. Therefore, this combination may represent a new treatment strategy for PCa.