Enhancer RNA IRS2e is essential for IRS2 expression and the oncogenic properties in oral squamous cell carcinoma.

The crucial roles of enhancer RNAs (eRNAs) in the regulation of gene expression in human diseases have drawn wider and wider attention in recent years. However, the specific expression profile and function of eRNAs are still rarely discussed in oral squamous cell carcinoma (OSCC), the most common subtype of head and neck squamous cell carcinoma (HNSC). In this study, we aimed to investigate the expression and function of an uncharacterized eRNA, insulin receptor substrate 2 enhancer RNA (IRS2e), in OSCC. We found that IRS2e was overexpressed in HNSC and its overexpression was positively correlated with a poor prognosis. The downregulation of IRS2e by short hairpin RNA significantly inhibited cell growth and induced cellular apoptosis and cell-cycle arrest in OSCC cells. Furthermore, the ablation of IRS2e inhibited tumor growth in vivo. Mechanically, IRS2e is essential for the expression of insulin receptor substrate 2 (IRS2), an oncogene nearby IRS2e in chromosome 13. Altogether, our study demonstrated that IRS2e is a novel oncogenic eRNA required for oncogene IRS2 expression in OSCC.