Long non‐coding RNA 91H contributes to the occurrence and progression of esophageal squamous cell carcinoma by inhibiting IGF2 expression

Long non‐coding RNAs (lncRNAs) have been recently recognized as a major class of regulators in mammalian systems. 91H, a novel long noncoding antisense transcripts located on the position of the H19/IGF2 locus has been suggested to play a potential tumor‐suppressor role in tumor development. However, little study has proved the mechanism in esophageal squamous cell carcinoma (ESCC). We carried out this study to explore the role of lncRNA 91H in the regulation of H19 imprinting control regions (ICR) and IGF2 expression and the association between 91H and ESCC progression. The cell line TE‐1, Eca‐109, and 232 ESCC patients' matched sets of paraffin‐embedded adjacent normal and tumor samples were obtained in this study. The results showed that 91H expression was significantly lower in patients with higher depth of invasion, neoplastic grading and TNM which usually leads to the overexpression of IGF2 in tumor progression. The expression of 91H usually decreased in TE‐1 and Eca‐109 when treated with demethylation agent. Further analysis revealed that, in 91H knockdown cell lines, IGF2 expression was also significantly higher than negative controls. Therefore, the results demonstrated that the lncRNA 91H was associated with H19 ICR methylation and inhibited IGF2 expression of ESCC patients which may optimize the mechanism of IGF2 regulation in tumor development. Patients with higher depth of invasion, neoplastic grading and TNM usually demonstrated lower 91H expression potentially represent a novel clinically relevant event to identify individuals at increased risk for the occurrence, progression and prognosis of ESCC. © 2014 Wiley Periodicals, Inc.