Downregulation of lncRNA CASC2 by microRNA-21 increases the proliferation and migration of renal cell carcinoma cells

Several long non-coding RNAs (lncRNAs) have been identified that may have a crucial role in tumor progression and metastasis. The lncRNA cancer susceptibility candidate 2 (CASC2) has previously been reported to act as a tumor suppressor gene in glioma and colorectal cancer. However, the expression and function of CASC2 in renal cell carcinoma (RCC) remains to be elucidated. The present study confirmed that CASC2 was downregulated in human RCC tissues and human RCC cell lines (786-O and A498). Restoration of CASC2 expression via transfection with a pcDNA3.1(+) -CASC2 vector was able to inhibit cell proliferation and migration in 786-O and A498 cells, as compared with in the cells transfected with a pcDNA3.1(+) empty vector. MicroRNA-21 (miR-21) has been reported to be upregulated in human RCC tissues and cell lines, and is associated with the malignant progression of RCC. In the present study, bioinformatics analysis and dual-luciferase reporter assays confirmed that CASC2 was a direct target gene of miR-21. miR-21 was able to decrease the expression of CASC2 in 786-O and A498 cells. Furthermore, overexpression of miR-21 partly abrogated CASC2-mediated inhibition of 786-O and A498 cell proliferation and migration. The present study provides evidence indicating that CASC2 targeted by miR-21 acts as a tumor suppressor in RCC. Therefore, CASC2 may be considered a novel target for the diagnosis and treatment of RCC.