Metformin enhances inhibitive effects of carboplatin on HeLa cell proliferation and increases sensitivity to carboplatin by activating mitochondrial associated apoptosis signaling pathway.

OBJECTIVE: Cervical cancer has become the fourth most common cancer in developing countries. This study aimed to investigate anti-tumor effects of Metformin combining with carboplatin in cervical cell line, HeLa cell. MATERIALS AND METHODS: Human cervical cancer cell line, HeLa cell, was treated with Metformin (5 mmol/l or 10 mmol/l) or/and carboplatin (25 mg/l or 50 mg/l) at different final concentrations, and divided into 8 groups. 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell viability. Acridine orange/ethidium bromide (AO/EB) staining was used to examine nuclear fragments and cell apoptosis. Annexin V/propidium iodide (PI) staining was employed to detect apoptosis of HeLa cells. Mitochondrial membrane potential of the HeLa cells was evaluated by staining with 5,5,6,6-tetrachloro-1,1,3,3-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) reagent. RESULTS: MTT results showed that Metformin combining carboplatin significantly reduced HeLa cell viability compared to that of no-drug treatment group (p<0.05). Metformin combining carboplatin significantly increased the amounts of nuclear fragments compared to that of no-drug treatment group (p<0.05). The flow cytometry assay results indicated that Metformin combining carboplatin significantly enhanced the apoptotic rates compared to that of no-drug treatment group (p<0.05). The JC-1 staining findings illustrated that Metformin combining carboplatin significantly decreased the mitochondrial membrane potential compared to that of no-drug treatment group (p<0.05). CONCLUSIONS: Metformin enhanced the inhibitive effects of carboplatin on HeLa cell proliferation. Metformin increased the sensitivity of HeLa cell to the treatment of Carboplatin by activating mitochondrial-associated apoptosis signaling pathway.