HOTAIR and cancer: However, emerging evidence has demonstrated that lncRNAs have important roles in various biological and pathological processes, such as the immune response,7 differentiation,8 metabolism,9 and cancer development and progression.10, 11, 12 As an emerging paradigm of cancer research, many cancer-specific lncRNAs have been identified, a set of which have been validated as biomarkers for metastasis or prognosis, such as metastasis associated long antisense transcript 1 (MALAT-1),13 HOX transcript antisense RNA (HOTAIR)14 and colon cancer-associated transcript 2 (CCAT2).