Osteopontin enhances cisplatin resistance of human A549 lung cancer cells via stimulating the PI3K signaling pathway and upregulating ERCC1 expression

Background: To investigate the regulatory role of osteopontin (OPN) in cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC). Methods: OPN over-expression and interference vectors were constructed. Human NSCLC A549 cells were divided into normal control, shRNA-NC, shRNA-OPN, OPN, negative control (NC), control+DDP, shRNA-NC+DDP, shRNA-OPN+DDP, OPN+DDP, and NC+DDP groups. Cell proliferation was measured by MTT assay. Cell apoptosis was detected by flow cytometry. PI3K (phosphoinositide 3-kinase), p-ERK1/2 (phospho-extracellular signal-regulated kinases) and ERCC1 (excision repair cross-complementation group 1) mRNA and protein expression was determined by real-time PCR and Western blot. Results: OPN overexpression and interference vectors were successfully constructed. When compared with control group, OPN group had significantly stimulated cell viability, reduced cell apoptosis, and increased expression of PI3K, p-ERK1/2 and ERCC1 (all P<0.05), whereas all other groups had lower cell viability, higher cell apoptosis, and inhibited protein expression. Moreover, OPN+DDP group had significantly higher proliferation, lower cell apoptosis, and enhanced PI3K, p-ERK1/2 and ERCC1 mRNA and protein expression compared with shRNA-OPN+DDP (all P<0.05). Conclusions: OPN can promote tumor cell growth and reduce cell apoptosis by activating PI3K pathway, which may induce the resistance of NSCLC to cisplatin. Moreover, the stimulation of ERCC1 expression may also increase the cisplatin resistance of NSCLCs.