A new tumor suppressor lncRNA RP11-190D6.2 inhibits the proliferation, migration, and invasion of epithelial ovarian cancer cells

At present, a large number of long noncoding RNAs (lncRNAs) from the human genome have been discovered. Meanwhile, emerging evidence has indicated that lncRNAs could play a critical role in the regulation of cellular processes such as cancer progression and metastasis. However, the functions of some new lncRNAs in the complex transcriptional process are mostly unknown at present. Existing studies suggest that loss of WW domain-containing oxidoreductase (WWOX) expression is linked with poor prognosis in numerous cancers, including epithelial ovarian cancer (EOC). However, the functional role of its antisense transcript RP11-190D6.2 is not clear to date. In this study, WWOX antisense transcript RP11-190D6.2 was analyzed specifically in EOC cells using real-time polymerase chain reaction and gain-/loss-of-function studies. We found that RP11-190D6.2 expression was positively correlated with WWOX expression. The RP11-190D6.2 expression was markedly downregulated in tumor tissues compared with normal tissues, but the RP11-190D6.2 expression was significantly downregulated in four EOC cell lines compared with human ovarian surface epithelial cell line. RP11-190D6.2 overexpression resulted in the increase of WWOX expression, whereas its knockdown led to the decrease of WWOX expression. We also found that RP11-190D6.2 was restored by 5-aza-2'-deoxycytidine treatment in EOC. In addition, the RP11-190D6.2 overexpression and knockdown experiments revealed that RP11-190D6.2 overexpression inhibited proliferation, migration, and invasion abilities in HO8910-PM cells, whereas RP11-190D6.2 knockdown in HEY-A8 cells had the opposite effect. The analyses in EOC implicate that RP11-190D6.2 may play a pivotal role in the regulation of tumor metastasis, suggesting that RP11-190D6.2 may serve as a potential biomarker and therapeutic target for EOC.