Combined therapeutic effect and molecular mechanisms of metformin and cisplatin in human lung cancer xenografts in nude mice.

OBJECTIVE: This work was aimed at studying the inhibitory activity of metformin combined with the commonly used chemotherapy drug cisplatin in human lung cancer xenografts in nude mice. We also examined the combined effects of these drugs on the molecular expression of survivin, matrix metalloproteinase-2 (MMP-2), vascular endothelial growth factor-C (VEGF-C), and vascular endothelial growth factor receptor-3 (VEGFR-3) to determine the mechanism of action and to explore the potential applications of the new effective drug therapy in lung cancer.
MATERIALS AND METHODS: The nude mice model of lung cancer xenografts was established, and mice were randomly divided into the metformin group, the cisplatin group, the metformin + cisplatin group, and the control group. The animals were killed 42 days after drug administration, and the tumor tissues were then sampled to detect the messenger ribonucleic acid (mRNA) and protein expression levels of survivin, MMP-2, VEGF-C, and VEGFR-3 by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR).
RESULTS: The protein and mRNA expression levels of survivin, MMP-2, VEGF-C, and VEGFR-3 in the cisplatin group and the combined treatment group were lower than that in the control group (P < 0.05). In the metformin group, the expression of MMP-2 protein and mRNA was lower than that in the control group (P < 0.05). The protein and mRNA expression levels of survivin, MMP-2, VEGF-C, and VEGFR-3 in the combined treatment group were lower than that in the cisplatin group and the metformin group (P < 0.05).
CONCLUSIONS: Metformin inhibited the expression of MMP-2, cisplatin and the combined treatment inhibited the expression of survivin, MMP-2, VEGF-C, and VEGFR-3, and the combined treatment of metformin with cisplatin resulted in enhanced anti-tumor efficacy.