Hsa_circ_0007142 contributes to cisplatin resistance in esophageal squamous cell carcinoma via miR‐494‐3p/LASP1 axis

BACKGROUND: Chemoresistance is one of the major obstacles for tumor treatment. Circular RNAs (circRNAs) have been confirmed to play vital roles in chemoresistance of cancer, including esophageal squamous cell carcinoma (ESCC). We investigated the roles and mechanisms of circ_0007142 in cisplatin (DDP) resistance of ESCC. METHODS: Quantitative real‐time polymerase chain reaction (qRT‐PCR) was conducted to determine the levels of circ_0007142, DOCK1 mRNA, microRNA‐494‐3p (miR‐494‐3p) and LIM And SH3 Protein 1 (LASP1) mRNA. RNase R assay was conducted to analyze the characteristic of circ_0007142. Cell Counting Kit‐8 (CCK‐8) assay was performed to evaluate IC50 of DDP. Flow cytometry analysis, 5‐ethynyl‐2’‐deoxyuridine (EdU) assay and transwell assay were carried out to examine cell apoptosis, proliferation and invasion, respectively. Dual‐luciferase reporter assay was employed to verify the association between miR‐494‐3p and circ_0007142 or LASP1. Murine xenograft assay was conducted to investigate the role of circ_0007142 in DDP resistant in vivo. The protein level of LASP1 in tumors was measured by Immunohistochemistry (IHC) analysis. RESULTS: Circ_0007142 was upregulated in DDP‐resistant ESCC tissues and cells. Circ_0007142 knockdown improved DDP sensitivity, induced cell apoptosis and hampered cell proliferation and invasion in DDP‐resistant ESCC cells. Circ_0007142 functioned as the sponge for miR‐494‐3p and miR‐494‐3p inhibition reversed the impacts of circ_0007142 knockdown on DDP resistance, cell apoptosis, proliferation, and invasion. LASP1 was a target of miR‐494‐3p, and the effects on DDP resistance, cell apoptosis, growth, and invasion mediated by LASP1 downregulation were rescued by miR‐494‐3p inhibition. Moreover, circ_0007142 knockdown enhanced DDP sensitivity in vivo. CONCLUSION: Circ_0007142 improved DDP resistance of ESCC by upregulating LASP1 via sponging miR‐494‐3p.