The role of lncRNA CASC2 on prognosis of malignant tumors: a meta-analysis and bioinformatics

Background: Cancer susceptibility candidate 2 (CASC2) is characterized as a tumor suppressor, which was first identified to be downregulated in endometrial carcinoma. Accumulating evidence was provided to testify the function of CASC2 in malignant tumors. However, a systematic and quantitative assessment is not available. The present study was designed to evaluate the role of CASC2 in multiple carcinomas through meta-analysis and bioinformatics. Materials and methods: A systematic assessment of the relationship of CASC2 with tumors was performed by using several computerized databases from inception to December 1, 2017. Pooled HR with 95% CI was calculated to summarize the effect. The data on prognosis of malignant tumors were also downloaded from The Cancer Genome Atlas (TCGA) project, OncoLnc, TANRIC and lncRNAtor database. Results: A total of 13 studies with 966 cancer patients were pooled in the analysis to evaluate the prognostic value of CASC2 in multiple tumors and the clinical features. The results of the meta-analysis revealed that low expression levels of CASC2 were associated with poor overall survival (OS) (pooled HR=0.39, 95% Cl: 0.28-0.53, P<0.0001). CASC2 obviously has a negative correlation with advanced tumor node metastasis (TNM) stage, lymph node metastasis (LNM) and T stage, respectively (P<0.05). There was, however, no significant difference in gender, distant metastasis and high differentiation (P> 0.05). In the Kaplan Meier curves with log-rank analysis, higher expression of CASC2 was positively correlated with longer survival time than patients with a lower level (P<0.05), including kidney renal clear cell carcinoma, brain lower grade glioma, pancreatic adenocarcinoma and sarcoma. Conclusion: Findings from this meta-analysis suggest that lower expression of CASC2 is associated with poorer prognosis of cancers, as well as advanced TNM, LNM and T stage. Data from the bioinformatics analysis revealed that higher expression of CASC2 was related to longer OS in patients with malignant tumors.