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

Abstract

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. 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. 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). 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.