Metformin In Combination With Gemcitabine Inhibites The Growth Of Non-small Cell Lung Cancer Cell Line H460in Vitro And Its Mechanisms Study

Objective: Gemcitabine, as the first-line chemotherapy drug, is widelyused in the treatment of non-small cell lung cancer (NSCLC).Unfortunately, low sensitivity of NSCLC patients to gemcitabine limits theclinical application of it. Recent studies suggest that there may be asynergistic antitumor effect between metformin and chemotherapy drugs.This study aims to investigate the effect of metformin combinedgemcitabine on the growth of NSCLC in vitro as well as its mechanisms.Methods: The concentration of combined metformin was determined byMTT assay. Then human NSCLC cell line H460was treated with differentconcentrations of gemcitabine alone or combined with metformin(5mM)and the cell proliferation of each group was measured by MTT assay andcompared with each other. Next, H460cell line was treated withgemcitabine at IC25(10nM), metformin(5mM), and metformin combinedgemcitabine. The apoptosis and cell cycle of NSCLC cells was detected bythe flow cytometry(FCM). Afterwards, H460cell line was treated with gemcitabine at IC50(30nM), metformin(5mM), and metformin combinedgemcitabine. Real-time PCR was used to detect the mRNA level of BIRC5,XIAP and Bim; the protein expressions of Bim, ERK1/2, p-ERK1/2, AKTand p-AKT were detected using Western blot. Results: Metformin canenhance the effect of gemcitabine at low concentration on the inhibition ofgrowth of H460cell in vitro. The combination of Gemcitabine andmetformin induced a higher percentage of cell apoptosis than that ofgemcitabine alone(48.38±1.55%vs.17.75±1.74%, P <0.01) and a weakerinvasive ability(15.8±7.66%vs.72.4±6.58%， P＜0.01), while had noinfluence on the cell cycle(P＞0.05). Metformin did not affect thetranscriptions of BIRC5(also called Survivin) and XIAP (P＞0.05) and theprotein expressions of AKT. However, it could promote thephosphorylation of AKT, decrease the phosphorylation of ERK1/2, andthen caused the rise of Bim expression. Conclusions: Metformin canpromote the inhibition of NSCLC growth induced by gemcibabine in vitro,that may be related with two critical mechanisms. One of which is thereduction of phosphorylation of ERK1/2and the following rise of Bimexpression; the other is enhancement of the effect on aggressive ability ofNSCLC cell in vitro.