Login to Access Video or Poster Abstract: MP73-08
Sources of Funding: Grant-in-Aid for Scientific Research (KAKENHI) 25464281

Introduction

Molecular targeted drugs have shown clinical benefit and improvement of their QOL for patients with advanced renal cell carcinoma. However, conquest of primary or acquired drug resistance is urgent problem in clinical practice. The previous reports have shown that Metformin is promising treatment approach for several cancers by regulating AMPK-mTOR pathway. In this study, we assessed whether combination of Metformin synergized molecular targeted drugs and repressed the progression of renal cancer model.

Methods

We tested synergy effect of Metformin combined with molecular targeted drugs, Everolimus and Axitinib. We assessed cell proliferation and apoptosis by WST-1 assay or a crystal violet assay and flow cytometry. We examined the gene expression profile of parental and molecular targeted drug resistant cells by microarray analysis. And protein expression of the AMPK-mTOR pathway by Western blot. The effects of combination treatment on A498 tumor growth was assessed in orthotropic renal cell carcinoma model.

Results

Combination of Metformin + Axitinib showed synergistic effect and more potently suppressed A498 cell growth rates in a dose and time dependent manner compared to Metformin or Axitinib monotherapy. Apoptosis detected by flow cytometry with Annexin V was most enhanced with combination treatment. We compared gene expression profile between parental and Axitinib resistant cell line, several pathways enhanced to survive from cellar stress. Metformin induced AMPK expression and suppressed Akt and mTOR expression in Axitinib treatment. In vivo, combination of Metformin + Axitinib therapy significantly repressed tumor growth compared with their mono therapy. In addition, micro vessel density and VEGF immunostaining were significantly reduced in tumor tissue of combination treatment.

Conclusions

Metformin showed synergistic effect for renal cell carcinoma growth combined with Axitinib in vitro and in vivo. Combination treatment of Metformin + Axitinib is providing pre-clinical proof-of-principle as a promising approach against drug resistance for renal cell carcinoma.

Funding

Grant-in-Aid for Scientific Research (KAKENHI) 25464281