Long non-coding RNAs (CASC2 and TUG1) in hepatocellular carcinoma: Clinical significance

Background: The biology of hepatocellular carcinoma remains poorly understood. Long non-coding RNAs (lncRNAs) have been confirmed to be key regulators of most cell processes and cancer. The lncRNA cancer susceptibility candidate 2 (CASC2) was originally identified as a downregulated gene in endometrial cancer and acted as a tumor suppressor. The lncRNA taurine up-regulated gene 1 (TUG1) has been shown to play an oncogenic role in various cancers. However, the relative expression of CASC2 and TUG1 in hepatocellular carcinoma (HCC) on top of hepatitis C virus (HCV) and the relationship between both remains unclear. The present study aimed to evaluate both lncRNA CASC2 and TUG1 relative gene expression in whole blood of HCC/HCV patients in relation to HCV and healthy subjects and to relate them to each other and to different clinicopathological factors. Methods: The relative expression of CASC2 and TUG1 was estimated by a quantitative reverse transcriptase-polymerase chain reaction in 30 HCC/HCV patients and compared with 20 cases of HCV patients and 20 controls. Results: CASC2 was downregulated in HCC/HCV patients, whereas TUG1 was overexpressed in relation to HCV and the control group, indicating their antagonistic effect. This suggests their role in the pathogenesis of HCC on top of HCV. Their expression was correlated to Barcelona Clinic Liver Cancer stage and serum alpha-fetoprotein level. Conclusions: CASC2 and TUG1 could be new potential biomarkers with a valid non-invasive technique.