β-catenin signaling pathway regulates cisplatin resistance in lung adenocarcinoma cells by upregulating Bcl-xl

The Wnt/β-catenin signaling pathway has been reported to regulate cisplatin resistance in several types of cancer cell. The present study aimed to investigate the role and underlying mechanism of Wnt/β-catenin signaling in cisplatin resistance of lung adenocarcinoma cells. Wild-type and cisplatin-resistant A549 human lung adenocarcinoma cells (A549/WT and A549/CDDP, respectively) were cultured in vitro and exposed to different cisplatin concentrations. Cells were incubated with 10 mM lithium chloride (LiCl) to activate β-catenin signaling. Cell proliferation was determined using the MTS assay. Cell apoptosis was evaluated using Annexin V/propidium iodide double staining, followed by flow cytometry. β-catenin was knocked down using small interfering RNA (siRNA). The intracellular distribution of β-catenin was determined by immunocytochemistry, and the mRNA and protein expressions of target genes were examined by reverse transcription-quantitative polymerase chain reaction and western zblotting, respectively. β-catenin and B-cell lymphoma-extra large (Bcl-xl) were significantly upregulated in A549/CDDP cells compared with A549/WT cells (P<0.05). LiCl reduced the sensitivity of A549/WT cells to cisplatin (P<0.01); and upregulated, increased phosphorylation (P<0.05) and enhanced nuclear translocation of β-catenin. LiCl also significantly elevated the mRNA and protein expression levels of Bcl-xl (P<0.05). Notably, silencing of β-catenin with siRNA decreased the mRNA and protein expression of Bcl-xl, and sensitized A549/WT cells to cisplatin (P<0.01). The findings of the current study suggest that upregulation of β-catenin signaling may contribute to cisplatin resistance in lung adenocarcinoma cells by upregulating Bcl-xl. Therefore, molecular targeting of Wnt/β-catenin signaling may sensitize lung cancer cells to cisplatin.