OTUB1-mediated deubiquitination of FOXM1 up-regulates ECT-2 to promote tumor progression in renal cell carcinoma

Kai Zhou,Weizhong Cai,Xu Yang,Zhenlin Chen,Bin Zhan,Haixing Mai,Song Zheng

doi:10.1186/s13578-020-00408-0

Kai Zhou, Weizhong Cai + Show 5 more

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https://doi.org/10.1186/s13578-020-00408-0

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Abstract

BackgroundOTUB1 (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.ResultsOTUB1 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.ConclusionsOTUB1-mediated deubiquitination of FOXM1 up-regulates ECT-2 to promote tumor progression in RCC, providing a new potential therapeutic target for RCC treatment.

Highlights

OTUB1mediated deubiquitination of FOXM1 (Forkhead box M1) participates in carcinogenesis of various tumors
OTUB1 was elevated in Renal cell carcinoma (RCC) tissues and cell lines To explore the correlation between OTUB1 and RCC, we analyzed the expression level of OTUB1 in RCC tissues and cell lines
Using qRT-PCR analysis, we found that OTUB1 was highly expressed in RCC tumor tissues compared to adjacent non-cancer specimens (Fig. 1a)

Summary

Introduction

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. In vivo subcutaneous xenotransplanted tumor model combined with immunohistochemistry and western blot were used to examine the tumorigenic function of OTUB1. Renal cell carcinoma (RCC) accounts for about 3% of all tumors with mortality rate as high as 40% [1, 2]. DUBs have been widely known as critical regulators in tumor development and progression [7], especially in RCC [8]. Ovarian tumor (OTU)-containing DUBs is one of the members of DUBs [9] and OTUB1 (ovarian tumor domain protease domain-containing ubiquitin aldehydebinding proteins) is a member of OTU domain protease superfamily of DUBs that removes ubiquitin from branched polyubiquitin chains in the target molecules [10]. The regulation ability and underlying mechanism of OTUB1 on RCC have not been reported yet

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