Abstract: AIM: To investigate the mechanism of acquired resistance remodeling to DDP (named cisplatin) by comparing the level of autophagy between the parental and DDP-resistant cells.  METHODS: Human lung adenocarcinoma A549 (parental cells) and A549/DDP cells (DDP-resistant cells) were treated with different concentrations of DDP, the drug resistance index (RI) was determined by CCK-8 assay and the autophagy associated proteins, like Beclin 1, LC3Ⅱ and p62 were measured by Western blot. A549 and A549/DDP cells were treated with 10 μmol/L DDP (about IC50 of A549 cells), the cell viability was determined by CCK-8 assay, the autophagy and apoptosis associated proteins (including Beclin 1, LC3Ⅱ, p62, Bcl-2, Bax and cleaved-caspase 3) were measured by Western blot, and the activity of transcription factor FOXO3a and its subcellular localization were detected by Western blot and laser confocal scanning microscopy. Finally, the autophagy inhibitor Baflomycin A1 (Baf A1) and the protein kinase inhibitor of PI3K/Akt signaling pathway were co-treated with DDP respectively to test the mechanism of drug resistance. RESULTS: Compared with the parental A549 cells, the acquired resistant A549/DDP cells showed DDP-resistance and higher level of basal autophagy. More survival count of A549/DDP cells than that of A549 cells in the same environment stress of 10 μmol/L DDP. 10 μmol/L DDP induced A549 cells apoptosis by down-regulated Bcl-2, and increased Bax and cleaved-caspase 3, which followed the inhibition of PI3K/Akt signaling pathway and up-regulated the expression level of transcription factor FOXO3a. While the same concentration of DDP activated A549/DDP cells autophagy by up-regulated Beclin 1 and LC3Ⅱ, down-regulated p62, which followed the inhibition of PI3K/Akt signaling pathway and inhibited the phosphorylation of FOXO3a. CONCLUSION: DDP induces apoptosis by up-regulating the transcription factor FOXO3a via inhibiting the PI3K/Akt/FOXO3a signaling pathway in A549 cells, while activating autophagy by inducing the phosphorylation of FOXO3a via inhibiting the PI3K/Akt/FOXO3a signaling pathway in A549/DDP cells.

Key words: lung adenocarcinoma, acquired DDP resistance, protective autophagy, PI3K/Akt/FOXO3a signaling pathway, apoptosis