The long non-coding RNA HOTAIR is upregulated in endometrial carcinoma and correlates with poor prognosis

Long non-coding RNAs (lncRNAs) are emerging as key molecules in human cancer. Homeobox (HOX) transcript antisense intergenic RNA (HOTAIR), a long non-coding RNA (lncRNA), is associated with a variety of human cancers, such as breast, liver and lung cancer. However, whether HOTAIR can function as a molecular marker in endometrial carcinoma (EC) remains unknown. In the present study, the expression of HOTAIR in 66 EC tissues from patients with EC and 30 normal tissues from healthy age-matched control subjects was determined using quantitative reverse transcription PCR. Furthermore, using in situ hybridization, we measured HOTAIR expression in 129 formalin-fixed paraffin-embedded (FFPE) tissue sections, which included 96 tissues that matched the frozen cases, 21 other EC tissues and 12 atypical hyperplasia tissues. Correlations between HOTAIR expression and the clinicopathological characteristics of patients were analyzed. Our results revealed that HOTAIR expression in the EC tissues was significantly upregulated compared with normal tissues (p<0.001). In addition, we observed a significant association between HOTAIR expression and the EC grade (p<0.05) and lymph node metastasis (p<0.05). Moreover, in the FFPE tissues, but not the frozen tissues, we found that a higher HOTAIR expression also correlated with the depth of myometrial invasion (p=0.019) and lymphovascular space invasion (p=0.015). More importantly, patients with a higher HOTAIR expression showed significantly poorer overall survival than those with lower HOTAIR expression (p<0.05). In conclusion, our results suggest that a high expression of HOTAIR is involved in the progression of cancer and may be a novel biomarker of poor prognosis in patients with EC.