Aberrant methylation-mediated silencing of lncRNA CTC-276P9.1 is associated with malignant progression of esophageal squamous cell carcinoma.

Downregulation and aberrant hypermethylation of long non-coding RNA CTC-276P9.1 have been detected in limited tumors. However, the distribution of methylated CpG sites and biological role of CTC-276P9.1 in esophageal squamous cell carcinoma (ESCC) progression and prognosis have not been fully clarified. The present study was to investigate the expression status and the distribution of methylated CpG sites within the three CpG islands of CTC-276P9.1, further to clarify its functional role and prognostic value in ESCC development and prognosis. Significant downregulation of CTC-276P9.1 was detected in esophageal cancer cells and ESCC tissues, and the expression of CTC-276P9.1 in ESCC tissues was associated with TNM stage, pathological differentiation, lymph node metastasis, and distant metastasis or recurrence. The expression level of CTC-276P9.1 in esophageal cancer cells was significantly reversed by treatment with 5-Aza-dC and TSA. The aberrant hypermethylation of the regions around the transcription start site was more tumor specific and associated with the expression levels of CTC-276P9.1. Moreover, histone modification may also participate in the regulation of CTC-276P9.1. Furthermore, over-expression of CTC-276P9.1 inhibited esophageal cancer cells proliferation and invasion in vitro, decreased the expression of proliferative markers and inhibited esophageal cancer cells invasion probably by regulating EMT. In addition, the dysregulation and hypermethylation of the regions around the transcription start site of CTC-276P9.1 were associated with poorer ESCC patients' survival. These findings suggest that CTC-276P9.1 may act as a tumor suppressor and may be employed as a new prognostic factor and therapeutic target for ESCC.