Long non-coding RNA HOXA-AS2 promotes tumorigenesis and predicts poor prognosis in ovarian cancer

// Changsheng Yan 1, 2, * , Mi Gong 1, * , Yi Jiang 1, * , Huijian Li 1, 3, 4, 5 , Yicong Wan 1 , Lin Zhang 6 , Shulin Zhou 1 and Wenjun Cheng 1 1 Department of Gynecology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China 2 Institute for Microbiota Ecology, Medical College of Xiamen University, Xiamen 361000, China 3 State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing 211166, China 4 Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing 211166, China 5 Wuxi Maternal and Child Health Hospital, Nanjing Medical University, Wuxi 214002, China 6 Department of Obstetrics and Gynecology, Zhongda Hospital Affiliated to Southeast University, Medical School, Southeast University, Nanjing 210029, China * These authors have contributed equally to this work Correspondence to: Wenjun Cheng, email: wenjunchengdoc@163.com Keywords: epithelial ovarian cancer (EOC); IncRNA-HOXA-AS2; apoptosis; caspase activation; Bcl-2 protein family Received: June 14, 2017     Accepted: January 02, 2018     Published: January 02, 2018 ABSTRACT Recent reports confirms that there are some long non-coding RNAs involved in the different biological regulatories in cancer, including proliferation and apoptosis. However, the correlation between the HOXA-AS2 expression and proliferation in epithelial ovarian cancer was not completely investigated. In vivo expression of HOXA-AS2 in 73 epithelial ovarian cancer tissues and 57 normal tissues was determined by qRT-PCR. Results showed that not only HOXA-AS2 was overexpressed in epithelial ovarian cancer tissues, but also had a relationship with the tumor size and FIGO stage of patients. Further, the overall survival in epithelial ovarian cancer patients presenting high expression of HOXA-AS2 was lower to those presenting low expression. Next, the functional effect of HOXA-AS2 was explored via GSEA analysis in ovarian cancer datasets. The results confirmed that HOXA-AS2 was enriched in cell apoptosis and JAK-STAT pathway. Then, EOC cell lines were transfected with HOXA-AS2 siRNA. Cell proliferation was significantly inhibited after knockdown of HOXA-AS2 via promoting apoptosis both in HO-8910 and SKOV3 cells. Reversely, overexpression of HOXA-AS2 in normal ovarian cell line could promote proliferation and inhibit apoptosis. Animal study consistently indicated that lower expression of HOXA-AS2 inhibited proliferation of HO-8910 cells. Finally, Western blot results showed that expressions of procaspase-9, -8, -3, and PARP were decreased after knockdown of HOXA-AS2, while cleaved Caspase-9, -8 and -3 were increased. Meanwhile, expressions of Bcl-2 and Bid were decreased and Bax was increased. In addition, overexpression of HOXA-AS2 increased the level of Bcl-2, Bid, JAK2 and Stat3 while Bax was decreased in HO8910 and SKOV3. Besides, the IHC assay also showed the same expression changes of Bcl-2 and Bax. To sum up, this study suggested that lncRNA HOXA-AS2 acted as an oncogene in EOC that partly inhibited the intrinsic mitochondria pathway and extrinsic death receptor pathway, which was associated with Bcl-2 protein family; HOXA-AS2 would be regarded as a new biological prognosis and potential therapeutic target of epithelial ovarian cancer.