Abstract: Background and purpose: Long non-coding RNA (lncRNA) is closely associated with carcinogenesis and tumor development. However, the function of lncRNA RP11-79H23.3 has not been reported yet. Therefore, the study aimed to investigate the role of lncRNA-RP11-79H23.3 in bladder cancer cells and its mechanism. Methods: Microarray analysis was performed on 4 cases of bladder cancer and cancer adjacent tissues. The relative expression levels of RP11-79H23.3 in bladder cancer tissues, paracancerous tissues of patients, normal bladder cells sv-HUC-1 and bladder cancer cells EJ were detected by real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR). pIRES2-RP11-79H23.3 was transfected into bladder cancer EJ cells by LipofectamineTM2000. The proliferation of EJ cells was detected by cell counting kit-8 (CCK-8) and EDU. The invasion and migration ability of EJ cells were detected by transwell assays and wound healing assay respectively. Apoptosis was detected by flow cytometry, Hoechst 33342 and TUNEL assay. The localization of PTEN in bladder cancer cells was detected by immunofluorescence. The cytoskeleton formation was observed by phalloidin staining. Western blot was adopted to analyze the protein expression levels of PI3K/AKT signaling pathway in EJ cells after RP11-79H23.3 transfection. Results: The expression levels of lncRNA RP11-79H23.3 in bladder cancer tissues and bladder cancer EJ cells were significantly downregulated (P<0.001, P<0.01). pIRES2-RP11-79H23.3 was transfected into EJ cells with a high transfection efficiency. Increased expression of RP11-79H23.3 could induce apoptosis of bladder cancer EJ cells. In contrast, overexpression of pIRES2-EGFP promoted the proliferation, invasion and migration, while transfection with pIRES2-RP11-79H23.3 suppressed stress fiber formation. Evidence from Western blot showed that RP11- 79H23.3 could upregulate the expression of PTEN in EJ cells and downregulate the expression of p-PI3K, p-AKT and p-Gsk3β (P<0.05). Conclusion: The expression of lncRNA RP11-79H23.3 is significantly downregulated in bladder cancer tissues and bladder cancer EJ cells (P<0.001, P<0.01). Moreover, the proliferation, migration and invasion of bladder cancer cells are restrained after the transfection with RP11-79H23.3. LncRNA RP11-79H23.3 may be related to PI3K/AKT signaling pathway. It is indicated that lncRNA RP11-79H23.3 plays an important role in bladder cancer and may become a target for the treatment of bladder cancer.

Key words: Bladder cancer, Long non-coding RNA, RP11-79H23.3, EJ cell