Long noncoding RNA CASC2 predicts the prognosis of glioma patients and functions as a suppressor for gliomas by suppressing Wnt/β-catenin signaling pathway

BACKGROUND Previous studies have demonstrated that long noncoding RNA cancer susceptibility candidate 2 (lncRNA CASC2) is frequently downregulated in several types of tumors and functions as a tumor-suppressive factor. However, the clinical significance and function of CASC2 in human glioma remain largely unknown. The purpose of this study was to identify the clinical values of CASC2, as well as investigate the potential molecular mechanisms in glioma. METHODS This retrospective study first analyzed the expression levels of CASC2 using quantitative real-time polymerase chain reaction. Then, CASC2 expression levels were associated with various clinicopathologic characteristics and the survival rate of patients with glioma. Finally, the function and underlying molecular mechanisms of CASC2 in human glioma were investigated in U251 cell line. RESULTS By quantitative real-time polymerase chain reaction analysis, our data showed that CASC2 expression was significantly downregulated in glioma tissues and cell lines (U87 and U251) compared to adjacent normal brain tissues or normal human astrocytes. Moreover, its expression negatively correlated with tumor grade in glioma patients. Furthermore, Kaplan-Meier curves with log-rank analysis revealed a close correlation between downregulated CASC2 and shorter survival time in glioma patients. In addition, Cox regression analysis indicated that CASC2 could be considered as an independent risk factor for poor prognosis. Finally, in vitro experiment demonstrated that CASC2 overexpression remarkably suppressed glioma cell proliferation, migration, and invasion through suppressing Wnt/β-catenin signaling pathway. CONCLUSION This study suggested that CASC2 may potentially serve as a valuable diagnostic and prognostic biomarker and a therapeutic target for glioma patients.