KDM6A, a histone demethylase, is frequently mutated in bladder cancer (BCa). However, the role and detailed molecular mechanism of KDM6A involved in bladder cancer progression remains unknown. Tissue specimens were used to determine the expression levels and prognostic values of KDM6A and ARHGDIB. The MTT, colony formation, wound healing and Transwell migration and invasion assays were employed to detect the BCa cell proliferation, migration and invasion, respectively. Chemotaxis of macrophages was used to evaluate the ability of KDM6A to recruit macrophages. A subcutaneous tumour model and tail vein tumour injection in nude mice were used to assess the role of KDM6A in vivo. RNA sequencing, qPCR, Western blot, ChIP and phalloidin staining assay were performed to investigate the molecular functions of KDM6A. Dual-luciferase reporter assay was used to determine the effects of KDM6A and FOXA1 on the promoters of the ARHGDIB and KDM6A. We showed that the KDM6A inhibited the motility and invasiveness of the BCa cells. Mechanistically, KDM6A promotes the transcription of ARHGDIB by demethylating histone H3 lysine di/trimethylation (H3K27me2/3) and consequently leads to inhibition of Rac1. EZH2, which catalyses the methylation of H3K27, functions to silence ARHGDIB expression, and an EZH2 inhibitor can neutralize the metastatic effect caused by KDM6A deficiency. Furthermore, we demonstrated that FOXA1 directly binds to the KDM6A promoter and thus transactivates KDM6A, leading to diminished metastatic potential. Our findings establish the critical role of the FOXA1-KDM6A-ARHGDIB axis in restraining the malignancy of BCa and identify KDM6A and EZH2 as potential therapeutic targets in the management of BCa.

中文翻译：

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KDM6A-ARHGDIB 轴通过抑制 Rac1 阻断膀胱癌转移

KDM6A 是一种组蛋白去甲基化酶，在膀胱癌 (BCa) 中经常发生突变。然而，KDM6A 在膀胱癌进展中的作用和详细的分子机制仍然未知。组织标本用于确定 KDM6A 和 ARHGDIB 的表达水平和预后价值。MTT、集落形成、伤口愈合和Transwell迁移和侵袭试验分别用于检测BCa细胞增殖、迁移和侵袭。巨噬细胞的趋化性用于评估 KDM6A 募集巨噬细胞的能力。使用裸鼠皮下肿瘤模型和尾静脉肿瘤注射来评估 KDM6A 在体内的作用。进行 RNA 测序、qPCR、蛋白质印迹、ChIP 和鬼笔环肽染色测定以研究 KDM6A 的分子功能。双荧光素酶报告基因测定用于确定 KDM6A 和 FOXA1 对 ARHGDIB 和 KDM6A 启动子的影响。我们发现 KDM6A 抑制了 BCa 细胞的运动性和侵袭性。从机制上讲，KDM6A 通过去甲基化组蛋白 H3 赖氨酸二/三甲基化 (H3K27me2/3) 促进 AHGDIB 的转录，从而抑制 Rac1。EZH2 催化 H3K27 的甲基化，起到沉默 ARHGDIB 表达的作用，而 EZH2 抑制剂可以中和 KDM6A 缺乏引起的转移效应。此外，我们证明 FOXA1 直接与 KDM6A 启动子结合，从而反式激活 KDM6A，导致转移潜能降低。