Long non-coding RNA CASC2 induces apoptosis and autophagy in human colon cancer cells via modulation of TRIM16 expression.

Long non-coding RNAs (LncRNAs) have been shown to be involved in diverse cellular and physiological processes. Recent studies have proved their potential as the prospective therapeutic targets for cancer treatment. Herein, we examined the role of LncRNA CASC2 in human colon cancer. The gene expression analysis showed that LncRNA CASC2 is significantly suppressed in colon cancer tissues and cell lines. The immunohistochemistry also showed considerable increase of the Ki67 in colon cancer tissues suggestive of their aggressiveness. Overexpression of CASC2 inhibited the growth of HT-29 cells. The inhibition of HT-29 growth was due to the induction of apoptosis which was accompanied by upsurge of Bax, depletion of Bcl-2 and activation of caspase-3 cleavage. Electron microscopic analysis showed CASC2 overexpression also induced autophagy in the HT-29 cells which was associated with increase in LC3B II and Beclin 1 expression. Bioinformatic approaches and dual luciferase assay showed that CASC2 controls the TRIM16 via microRNA-214 axis. TRIM16 was found to be overexpressed in all the colon cancer tissues and cell lines. Overexpression of CASC2 caused significant inhibition of TRIM16. Additionally, silencing of TRIM16 resulted in the inhibition of HT-29 cell growth similar to that of CASC2 overexpression. Taken together, CASC2 may prove to be an important therapeutic target for colon cancer treatment.