Long noncoding RNA CCAT2 correlates with smoking in esophageal squamous cell carcinoma.

Esophageal cancer is one of the leading causes of cancer-related mortality, and most esophageal squamous cell carcinoma (ESCC) cases are located in Asian area. Recent studies about long noncoding RNAs (lncRNA) have offered a new perspective for cancer research and provided new approaches to understand the complex regulation network in cancer. Our group has reported that the novel lncRNA colon cancer-associated transcript 2 (CCAT2) has important biological function and could be a potential biomarkers in lung cancer. Here, we performed in silico analysis and characterized the expression profile of CCAT2 in a cohort of esophageal squamous cell carcinoma (ESCC) patients and cell lines. In silico analysis showed that no CpG island is found in the chromosome region of CCAT2, indicating that the expression of CCAT2 is possibly not regulated by DNA methylation. Compared with paired adjacent normal esophageal tissues, CCAT2 was significantly overexpressed in ESCC tissues with an average fold of 7.18. In ESCC cell lines, CCAT2 was mostly upregulated in KYSE410 cell (24.7-fold upregulation) when normalized to normal esophageal epithelium cell line (HEEC) and most CCAT2 transcripts were located in nucleus (> 95 %). Statistical analysis showed that CCAT2 expression level was significantly associated with smoking status (P = 0.036). Receiver operative curve and the area under curve were calculated to assess the diagnostic potential of CCAT2. Measured by area under curve (AUC), CCAT2 showed higher diagnostic performance than conventional serum biomarkers, like AFP, CA153, and NSE. In this study, we firstly characterized the expression profile of CCAT2 in ESCC and evaluated its potential diagnostic value as a biomarker.