Yang-Yin-Jie-Du decoction overcomes gefitinib resistance in non-small cell lung cancer via down-regulation of the PI3K/Akt signalling pathway.

CONTEXT: Yang-Yin-Jie-Du Decoction (YYJDD) was used to improve gefitinib efficacy in our clinical practice, but its mechanism remains unclear. OBJECTIVE: This study explored if YYJDD could reverse gefitinib resistance. MATERIALS AND METHODS: H1975 cells were exposed to control, 10 µM gefitinib, 3.2 mg/mL YYJDD or combination treatment. Cell viability was detected by MTT during 0-96 h. Apoptosis and the PI3K/Akt proteins were tested by flow cytometry and western-blot at 24 h. LY294002 was applied to further determine the role of the PI3K/Akt. 23 BALB/c nude xenograft mice received normal saline (n = 5), 80 mg/kg gefitinib (n = 6), 2.35 g/kg lyophilised powder of YYJDD (n = 6) or combination treatment (n = 6) by gavage for 4 weeks and submitted to TUNEL, immunohistochemistry, and western-blot. RESULTS: In vitro, gefitinib (IC50: 20.68 ± 2.06 µM) and YYJDD (IC50: 6.6 ± 0.21 mg/mL) acted in a moderate synergistic way. Combination treatment inhibited cell viability from 100% to 25.66%. Compared to gefitinb (33.23 ± 3.99%), cell apoptosis was increased with combination treatment (54.11 ± 7.32%), accompanied by down-regulation of the PI3K/Akt. LY294002 further inhibited cell viability, increased apoptosis, and down-regulated p-Akt/Akt. In vivo, the tumour sizes in the combination group (1165.13 ± 157.79 mm3) were smaller than gefitinib alone (1630.66 ± 208.30 mm3). The positive rate of TUNEL staining was increased by combination treatment (22.33 ± 2.75%) versus gefitinib (7.37 ± 0.87%), while the PI3K/Akt was down-regulated. DISCUSSION AND CONCLUSION: YYJDD has potential to overcome gefitinib resistance. Future investigations should be focussed on its specific targets.