Abstract

Since radioresistance is a common challenge leading to decreased efficiency of radiotherapy for esophageal squamous cell carcinoma (ESCC), no effective treatment strategy has yet been upheld. The current study aimed to explore whether long non-coding RNAs (lncRNA) cancer susceptibility 15 (CASC15) binding to microRNA-140-5p (miR-140-5p) affects ESCC radiosensitivity. Firstly, up-regulated levels of lncRNA CASC15 were found in ESCC tissues and cells. Next, in order to evaluate the effect of lncRNA CASC15 on ESCC, we performed a series of in vitro experiments after transfecting the plasmids into KYSE270 and EC109 cells. Results revealed that lncRNA CASC15 silencing contributed to anti-proliferative, anti-invasive and pro-apoptotic properties in ESCC cells. As validated by dual-luciferase reporter assay, lncRNA CASC15 could competitively bind to miR-140-5p that targeted MMP7. Further examination revealed that MMP7 was highly-expressed while miR-140-5p was poorly expressed in ESCC tissues and cells. Meanwhile, the data obtained from radiosensitivity experimentation demonstrated that lncRNA CASC15 elevation inhibited radiosensitivity and apoptosis, yet increased proliferation by binding to miR-140-5p and up-regulating MMP7. Moreover, silencing lncRNA CASC15 in vivo enhanced the radiosensitivity of ESCC cells. Collectively, silencing lncRNA CASC15 enhances radiosensitivity of ESCC through miR-140-5p-dependent inhibition of MMP7, highlighting promising new targets for ESCC treatment.