LINC00261 is an epigenetically-regulated tumor suppressor that is essential for activation of the DNA damage response

Lung cancer is the leading cause of cancer-related death in the United States. Long non-coding RNAs (lncRNAs) are a class of regulatory molecules whose role in lung carcinogenesis is poorly understood. In this study, we profiled lncRNA expression in lung adenocarcinoma (LUAD) cell lines, compared their expression to that of purified alveolar epithelial type II cells (the purported cell of origin for LUAD), cross-referenced these with lncRNAs altered in primary human tumors, and interrogated for lncRNA whose expression correlated with patient survival. We identified LINC00261, a lncRNA with unknown function in LUAD, adjacent to the pioneering transcription factor FOXA2. Loss of LINC00261 was observed in multiple tumor types, including liver, breast, and gastric cancer. Reintroduction of LINC00261 into human LUAD cell lines inhibited cell migration and slowed proliferation by inducing a G2/M cell cycle arrest while upregulating DNA damage pathway genes and inducing phosphorylation-mediated activation of components of the DNA damage pathway. FOXA2 was able to induce LINC00261 expression, and the entire locus underwent hypermethylation in LUAD, leading to loss of expression. We have thus identified an epigenetically deregulated lncRNA, whose loss of expression in LUAD promotes the malignant phenotype and blocks activation of the DNA damage machinery, predisposing lung cells to cancer development.

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