OTUB1 (ovarian tumor domain protease domain-containing ubiquitin aldehyde-binding proteins)-mediated deubiquitination of FOXM1 (Forkhead box M1) participates in carcinogenesis of various tumors. We aim to investigate the effect and mechanism of OTUB1/FOXM1 on RCC (renal cell carcinoma) progression. Expression levels of OTUB1 in RCC tissues and cell lines were examined by qRT-PCR (quantitative real-time polymerase chain reaction) and immunohistochemistry. Cell proliferation was measured with CCK8 (Cell Counting Kit-8) and colony formation assays. Wound healing and transwell assays were used to determine cell migration and invasion, respectively. The effect of OTUB1 on FOXM1 ubiquitination was examined by Immunoprecipitation. Western blot was used to uncover the underlying mechanism. In vivo subcutaneous xenotransplanted tumor model combined with immunohistochemistry and western blot were used to examine the tumorigenic function of OTUB1. OTUB1 was up-regulated in RCC tissues and cell lines, and was associated with poor prognosis of RCC patients. Knockdown of OTUB1 inhibited cell viability and proliferation, as well as migration and invasion of RCC cells. Mechanistically, knockdown of OTUB1 down-regulated FOXM1 expression by promoting its ubiquitination. Down-regulation of FOXM1 inhibited ECT2 (epithelial cell transforming 2)-mediated Rho signaling. Moreover, the inhibition of RCC progression caused by OTUB1 knockdown was reversed by FOXM1 over-expression. In vivo subcutaneous xenotransplanted tumor model also revealed that knockdown of OTUB1 could suppress in vivo RCC growth via down-regulation of FOXM1-mediated ECT2 expression. OTUB1-mediated deubiquitination of FOXM1 up-regulates ECT-2 to promote tumor progression in RCC, providing a new potential therapeutic target for RCC treatment.

中文翻译：

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OTUB1介导的FOXM1去泛素化上调ECT-2促进肾细胞癌的肿瘤进展

OTUB1（含卵巢肿瘤结构域蛋白酶结构域的泛素醛结合蛋白）介导的 FOXM1（叉头盒 M1）去泛素化参与各种肿瘤的癌变。我们旨在研究 OTUB1/FOXM1 对 RCC（肾细胞癌）进展的影响和机制。通过 qRT-PCR（定量实时聚合酶链反应）和免疫组织化学检查 RCC 组织和细胞系中 OTUB1 的表达水平。用 CCK8 (Cell Counting Kit-8) 和集落形成测定法测量细胞增殖。伤口愈合和 transwell 测定分别用于确定细胞迁移和侵袭。通过免疫沉淀检查 OTUB1 对 FOXM1 泛素化的影响。蛋白质印迹用于揭示潜在机制。采用体内皮下异种移植肿瘤模型结合免疫组化和western blot检测OTUB1的致瘤功能。OTUB1 在 RCC 组织和细胞系中上调，与 RCC 患者预后不良有关。敲除 OTUB1 可抑制细胞活力和增殖，以及 RCC 细胞的迁移和侵袭。从机制上讲，OTUB1 的敲低通过促进其泛素化来下调 FOXM1 的表达。FOXM1 的下调抑制了 ECT2（上皮细胞转化 2）介导的 Rho 信号传导。此外，由 OTUB1 敲低引起的 RCC 进展抑制被 FOXM1 过表达逆转。体内皮下异种移植肿瘤模型还显示，敲除 OTUB1 可通过下调 FOXM1 介导的 ECT2 表达来抑制体内 RCC 生长。OTUB1 介导的 FOXM1 去泛素化上调 ECT-2 促进 RCC 肿瘤进展，为 RCC 治疗提供新的潜在治疗靶点。