Fuzheng Kang-Ai decoction enhances the effect of Gefitinib-induced cell apoptosis in lung cancer through mitochondrial pathway.

Our previous clinical study has shown that Chinese herbal medicine (CHM) Fuzheng Kang-Ai (FZKA) decoction is effective in treating advanced lung cancer patients through prolonging the drug resistance to Gefitinib (GFTN). Our basic study found that FZKA decoction could enhance the inhibition effect of GFTN in lung cancer by inactivating PI3K/Akt pathway. Moreover, our recent work showed that FZKA induced lung cancer cell apoptosis via STAT3/Bcl-2/Caspase-3 pathway. Thus in this study, we aim to elucidate how FZKA enhances the effect of GFTN in lung cancer from the perspective of cell apoptosis. Cell proliferation and colony formation assay were performed to detect the cell growth inhibition. Flow cytometry and TUNEL assay were carried out to test the cell apoptosis. Mitochondrial membrane potential (MMP) assay was done to measure the alteration of MMP. Caspase-3/-9 activity assay was used to test the activity of caspase-3/-9. Western blot and qRT-PCR were done to detect the expression of STAT3 and Bcl-2 family as well as Caspase-3/-9 and Cyt-C at protein and mRNA levels, respectively. Transient transfection was performed to silence STAT3 using siSTAT3. Animal model was done to validate the molecular mechanisms in vivo and immunohistochemistry was done to detect the expression of Bax and Caspase-3. Firstly, our results showed that FZKA enhanced the inhibition effect of GFTN in lung cancer both in vitro and in vivo. Secondly, cell apoptosis was enhanced when treating lung cancer cells with both FZKA and GFTN, a process involving the mitochondria and the Bcl-2 family. And Bcl-2 family was involved in this process. Interestingly, STAT3 plays a critical role on mediating the above process. Last but not the least, the enhanced effect of cell apoptosis induction of GFTN by FZKA was validated in animal model. Our findings conclude that Fuzheng Kang-Ai decoction enhances the effect of GFTN-induced cell apoptosis in lung cancer through the mitochondrial pathway, providing a novel molecular mechanism by which FZKA sensitizes to GFTN by delaying drug resistance in treating lung cancer patients.