LncRNA CASC2 expression is down- regulated in papillary thyroid cancer and promotes cell invasion by affecting EMT pathway.

BACKGROUND: Long non-coding RNAs (lncRNAs) were recently identified as crucial regulators of papillary thyroid cancer (PTC). However, the clinical role and regulatory functions of lncRNA cancer susceptibility candidate 2 (CASC2) in PTC remain unknown.

METHODS: LncRNA CASC2 expression was examined in plasma samples from 68 PTC patients and 39 patients with nodular goiter (NG). Cell proliferation, migration and invasion abilities were evaluated using CCK8 assay and transwell migration and invasion assay. QRT-PCR and western blot analysis were performed to detect the expression of epithelial-to-mesenchymal (EMT) markers ZEB1, E-cadherin and vimentin in PTC cells.

RESULTS: We demonstrated that lncRNA CASC2 expression was significantly downregulated in tumor tissues and plasma samples in patients with PTC compared with those in nodular goiters (P< 0.05). Decreased plasma lncRNA CASC2 expression associated with lymph node metastasis (LNM) of PTC patients and was identified as an independent risk for patients with LNM (P< 0.05). Furthermore, functional assays demonstrated that overexpression of lncRNA CASC2 inhibited cell proliferation, migration and invasion of PTC. Moreover, we demonstrated that overexpression of lncRNA CASC2 suppressed cell epithelial-mesenchymal transition (EMT) process of PTC by increasing the E-cadherin expression, but downregulating ZEB1 and N-cadherin expression.

CONCLUSIONS: Thus, these results indicated that lncRNA CASC2 was a predictor for LNM of PTC patients and may serve as a potential target of PTC treatment.