Unveiling the antitumor synergy between pazopanib and metformin on lung cancer through suppressing p-Akt/ NF-κB/ STAT3/ PD-L1 signal pathway

Pazopanib, an inhibitor of the VEGF receptor tyrosine kinase, has demonstrated significant antitumor effects in lung cancer. However, its application as a standard treatment for this type of cancer is limited by its drug resistance and toxicity. Metformin has the potential to combat lung cancer by modifying the tumor's immune microenvironment. In this study, we investigated the potential antitumor effects and the associated underlying molecular mechanisms of the combination of pazopanib and metformin in lung cancer. In vitro studies were conducted using the A549 and H460 lung cancer cell lines, whereas urethane-induced lung cancer-bearing mice were used for in vivo assessments. The urethane-induced mice received oral administration of pazopanib (50 mg/kg) and/or metformin (250 mg/kg) for a duration of 21 days. The results indicated that the MTT assay demonstrated a combined cytotoxic effect of the pazopanib/metformin combination in H460 and A549 cells, as evidenced by CI and DRI analyses. The observed increase in annexin V levels and the corresponding increase in Caspase-3 activity strongly suggest that this combination induced apoptosis. Furthermore, the pazopanib/metformin combination significantly inhibited the p-Akt/NF-κB/IL-6/STAT3, HIF1α/VEGF, and TLR2/TGF-β/PD-L1 pathways while also increasing CD8 expression in vivo. Immunohistochemical analysis revealed that these antitumor mechanisms were manifested by the suppression of the proliferation marker Ki67. In conclusion, these findings revealed that metformin augments the antitumor efficacy of pazopanib in lung cancer by simultaneously targeting proliferative, angiogenic, and immunogenic signaling pathways, metformin enhances the antitumor effectiveness of pazopanib in lung cancer, making it a promising therapeutic option for lung cancer.