Reversal Of Cisplatin Resistance By Inhibiting PI3K/Akt Signal Pathway In Human Lung Cancer Cells

Cisplatin is one of the frequently-used chemotherapy drugs in lung cancer clinical treatment, especially for small cell lung cancer(SCLC). However, the efficacy is usually limited for drug resistance after a period of treatment.In this study, we obtain three drug-resistant strains of lung cancer cells(H446/DDP, H460/DDP and A549/DDP cells) which induced by cisplatin. Then, we got a deeply insight into the relationship between PI3K/Akt and Cisplatin-resistant in lung cancer by MTT, CCK8, flow cytometry and Westernblot assay, demonstrated that cisplatin-resistant of lung cancer could be reversed by inhibition of PI3K/Akt signaling pathway in lung cancer cells.The research results we got are shown below:1)3 lung carcinoma cells had got the ability of cisplatin-resistant. The value of IC50 for H446/DDP, H460/DDP and A549/DDP cells are 27.0c1.3 ?mol/L,53.0±5.2 ?mol/L and 70.7±3.5 ?mol/L respectively, compare with their parental strains which the value of IC50 are 2.4?mol/L,8.8±1.5 ?mol/L and 11.4±2.8 ?mol/L, the resistance index are 11.3,6.land 6.2 respectively.2) compare with their their parental strains, thedrug-resistant strains shown theslower grown mode, which suggest that the drug-resistant cell strains may avoid cisplatin damage by taking initiative to cell cycle adjustment.3) we found that Akt expression and activity was increased in drug-resistant strains when compared to their parental cells, which reminder a vital link between PI3K/Akt signal pathway and Cisplatin resistant.4) After treated with moderate wortmannin(5.0 ?mol/L for H446/DDP cell and H460/DDP cell,2.5 ?mol/L for A549/DDP cell), the Akt phosphorylation levels can be hauled to the levels which correspond with parent cell lines.5) MTT assay showed that the IC50 values of Cisplatin for H446/DDP, H460/DDP and A549/DDP cells were 2.4±1.3 ?mol/L,6.7±0.3 ?mol/L and 9.6±1.2 ?mol/L after treated with wortmannin, while the IC50 values were 27.0±1.3 ?mol/L,53.0±5.2 ?mol/L and 70.7±3.5 ?mol/L in cisplatin only group.6) Flow cytometry experiments showed that wortmannin could sensitize cisplatin-resistant cells to cisplatin. Combination treatment of wortmannin with cisplatin is able to increase the Apoptosis rate of H446/DDP, H460/DDP and A549/DDP cells from 40.0%,16.8% and 21.7% to 60.5%,46.9% and 58.7%.7) wortmannin could enhance the activity of Caspase-3,Caspase-8 and Caspase-9 in cisplatin therapy. The result suggested that combinated therapy are easier to launch the Caspase-mediated apoptotic cascade reation than cisplatin only group.8) The present study also demonstrated that hyperactivation of PI3K/Akt/Bad pathway is closely associated with cisplatin resistance by regulating the Bc1-2/Bax-mitochondria-mediated apoptosis pathway in human lung cancer. Inhibition of PI3K-Akt activity could reverse the cisplatin-resistent by restarting this apoptosis pathway...