The long noncoding RNA KTN1-AS1 promotes bladder cancer tumorigenesis via KTN1 cis-activation and the consequent initiation of Rho GTPase-mediated signaling

Abstract Background: Accumulating evidence support the hypothesis that long noncoding RNAs (lncRNAs) are involved in several physiological and pathological conditions, including cancer. Here, we investigated the potential role of lncRNAs in bladder cancer. Methods: We first looked at available datasets retrieved from the TCGA database and discovered that the lncRNA KTN 1 antisense RNA 1 (KTN1-AS1) was significantly up-regulated in several cancer types including bladder cancer, but was decreased in some other tumors. Therefore, we focused our attention on KTN1-AS1. Using both in vitro and in vivo systems that allowed the modulation of KTN1-AS1 and expression of other relevant proteins, we investigated in-depth the role of KTN1-AS1 in bladder cancer (and the mechanism behind). We further investigated the potential KTN1-AS1-interacting proteins using RNA immunoprecipitation, and explored the KTN1-AS1-related epigenetic landscape (with a particular emphasis on acetylation) using chromatin immunoprecipitation (ChIP) assays. Results: KTN1-AS1 silencing inhibited the proliferation, invasion, and migration of bladder cancer cells, while KTN1-AS1 overexpression had the obvious opposite effects. Mechanistically, KTN1-AS1 promoted the recruitment of EP300, a histone acetyltransferase that enriched acetylation of histone H3 at lysine 27 (H3K27Ac) in the KTN1 promoter region. This epigenetic modulation contributed to the up-regulation of KTN1, which affected bladder cancer growth and progression via the regulation of Rho GTPase (RAC1, RHOA, and CDC42)-mediated signaling. Conclusion: Overall, our data support the idea that the lncRNA KTN1-AS1 promotes bladder cancer tumorigenesis via modulation of the KTN1/Rho GTPase axis and is a promising new therapeutic target for the treatment of bladder cancer.