SMYD3 confers cisplatin chemoresistance of NSCLC cells in an ANKHD1-dependent manner

BACKGROUND: Cisplatin (DDP) remains the backbone of chemotherapy for non-small cell lung cancer (NSCLC), yet its clinical efficacy is limited by DDP resistance. We aim to investigate the role of the SET and MYND domain-containing protein 3 (SMYD3) in DDP resistance of NSCLC. METHODS: Expression pattern of SMYD3 was determined in NSCLC tissues using qRT-PCR, which also validated its correlation with NSCLC clinicopathological stages. Impacts of SMYD3 on DDP resistance were evaluated by knocking down SMYD3 in DDP-resistant cells and overexpressing it in DDP-sensitive cells, and assessed for several phenotypes: IC(50) by MTT, long-term proliferation by colony formation, apoptosis and cell-cycle distribution by flow cytometry. The interaction between Ankyrin Repeat and KH Domain Containing 1 (ANKHD1) and SMYD3 was examined by co-immunoprecipitation and immunofluorescence. The transcriptional regulation of SMYD3 on cyclin-dependent kinase 2 (CDK2) promoter regions was confirmed using chromatin-immunoprecipitation. The in vivo experiments using DDP-resistant cells with altered SMYD3 and ANKHD1 expression were further performed to verify the SMYD3/ANKHD1 axis. RESULTS: Highly expressed SMYD3 was observed in NSCLC tissues or cells, acted as a sensitive indicator for NSCLC, correlated with higher TNM stages or resistant to DDP treatment, and shorter overall survival. The promotion of SMYD3 on DDP resistance requires co-regulator, ANKHD1. CDK2 was identified as a downstream effector. In vivo, SMYD3 knockdown inhibited the growth of DDP-resistant NSCLC cells, which was abolished by ANKHD1 overexpression. CONCLUSIONS: SMYD3 confers NSCLC cells chemoresistance to DDP in an ANKHD1-dependent manner, providing novel therapeutic targets to overcome DDP resistance in NSCLC .