Deubiquitylase OTUD6B stabilizes the mutated pVHL and suppresses cell migration in clear cell renal cell carcinoma

Wenyong Wu,Kai Guo,Chun-Ping Cui,Lingqiang Zhang,Xinxin Liu,Zhengsheng Wu,Ze Wang,Yinghua Wei,Xiaoli Zhang,Xin Zhang

doi:10.1038/s41419-021-04135-3

Abstract

Von Hippel-Lindau (VHL) is an important tumor suppressor, and its inactivation is a hallmark of inherited VHL disease and most sporadic clear cell renal cell carcinoma (ccRCC). VHL protein (pVHL) with missense point mutations are unstable and degraded by the proteasome because of the disruption of elongin binding. Deubiquitylase ovarian tumor domain-containing 6B (OTUD6B) had been documented to couple pVHL and elongin B to form stable VHL - elonginB - elonginC complex, which protects pVHL from degradation. However, whether OTUD6B governs the stability of pVHL wild type and the missense mutants in ccRCC remains largely elusive. Here, we reported that low OTUD6B level predicted poorer survival in ccRCC patients with VHL missense mutation, but not frameshift deletion and nonsense mutation. OTUD6B is able to interact with wild type pVHL and tumor-derived pVHL missense mutants, except for pVHL I151T, and decrease their ubiquitylation and proteasomal degradation in ccRCC cells. Functionally, we revealed that OTUD6B depletion enhanced cell migration and HIF-2α level in ccRCC cells in a pVHL dependent manner. In addition, OTUD6B depletion reduced the inhibitory effects of ectopic pVHL missense mutants on cell migration and HIF-2α level, except for pVHL I151T. Thus, we speculated that I151 residue might be one of key sites of pVHL binding to OTUD6B. These results suggested that OTUD6B is an important regulator for the stability of pVHL missense mutants, which provides a potential therapeutic strategy for ccRCC with VHL mutations.

Highlights

The von Hippel-Lindau (VHL) tumor suppressor is responsible for substrate recognition in the Cullin-RING ubiqutin ligase complex, which is composed of Cullin 2, elongin B, elongin C, and Rbx1, entitled as Cul2-elonginB/C (CBC) complex [1,2,3,4]
Low ovarian tumor domain-containing 6B (OTUD6B) level predicted poor survival in clear cell renal cell carcinoma (ccRCC) patients with VHL missense mutation Clear cell Renal cell carcinoma (RCC), the most common type of RCC, is closely associated with VHL gene mutations that lead to stabilization of Hypoxia inducible factor (HIF)-α in both sporadic and inherited forms [9, 10]
To identify the relationship between pVHL level with the prognosis of ccRCC patients, we analyzed the proteomic results of 471 samples of human ccRCC from The Cancer Genome Atlas (TCGA) dataset

Summary

Introduction

The von Hippel-Lindau (VHL) tumor suppressor is responsible for substrate recognition in the Cullin-RING ubiqutin ligase complex, which is composed of Cullin 2, elongin B, elongin C, and Rbx, entitled as Cul2-elonginB/C (CBC) complex [1,2,3,4]. VHL disease, resulted from germline mutations in VHL gene, is an autosomal dominant disease and predisposes to highly vascularized tumors, and the most frequent manifestations are hemangioblastomas of the central nervous system and retina, ccRCC, and pheochromocytomas [11]. Up to 80% of ccRCC have the inactivated VHL gene [13, 14] which leads to HIF-α accumulation and the activation of HIF target genes which promote tumor angiogenesis, invasion, metabolic reprogramming, and metastasis [15, 16]. Therapies targeting HIF indirectly, such as vascular endothelial growth factor (VEGF) inhibitors, are the first-line treatments for ccRCC, but most patients develop drug resistance [17, 18]. It is essential to explore the mechanisms underlying pVHL inactivation for the development of potential therapeutic strategy for ccRCC

Methods

Results

Conclusion