Small GTPase RHOE/RND3, a new critical regulator of NF-κB signalling in glioblastoma multiforme?

Abstract

OBJECTIVES:

Abnormal activation of NF-κB signalling is a major mechanism of apoptosis resistance in glioblastoma multiforme (GBM). Therefore, better understanding of the regulation of NF-κB signalling has a significant impact for GBM therapy. Here, we uncovered a critical role of the small GTPase RND3 in regulating the p65 subunit of NF-κB and NF-κB signalling in GBM.

MATERIALS AND METHODS:

Human GBM samples, GBM cells and a human orthotopic GBM-xenografted animal model were used. The mechanisms of RND3 in regulation of NF-κB signalling and GBM cell apoptosis were examined by luciferase assay, quantitative PCR, immunostaining, immunoblotting, immunofluorescence, coimmunoprecipitation, TUNEL staining, JC-1 analysis and flow cytometry.

RESULTS:

Overexpression of RND3 led to reduced p65 activity in GBM-cultured cells and a GBM animal model, indicating that the NF-κB pathway is negatively regulated by RND3 in GBM. Mechanistically, we found that RND3 bound p65 and promoted p65 ubiquitination, leading to decreased p65 protein levels. Furthermore, RND3 enhanced cleaved caspase 3 levels and promoted apoptosis in GBM cells, and RND3 expression was positively correlated with cleaved caspase 3 and IL-8 in human GBM samples. The effect of RND3 on promoting apoptosis disappeared when p65 ubiquitination was blocked by protease inhibitor carfilzomib or upon co-expression of ectopic p65.

CONCLUSIONS:

RND3 binds p65 protein and promotes its ubiquitination, resulting in reduced p65 protein expression and inhibition of NF-κB signalling to induce GBM cell apoptosis.

• Authors: Qian Sun, Huimin Dong, Yuntao Li, Fan'en Yuan, Yang Xu, Shanping Mao, Xiaoxing Xiong, Qianxue Chen, Baohui Liu
• Journal: Cell proliferation (Cell Prolif) Vol. 52 Issue 5 Pg. e12665 (Sep 2019) ISSN: 1365-2184 [Electronic] England
• PMID: 31332862 (Publication Type: Journal Article)
• Copyright: © 2019 The Authors. Cell Proliferation Published by John Wiley & Sons Ltd.

Chemical References

• Interleukin-8
• Oligopeptides
• RELA protein, human
• Transcription Factor RelA
• carfilzomib
• Caspase 3
• RND3 protein, human
• rho GTP-Binding Proteins

Topics

• Animals
• Apoptosis (drug effects)
• Brain Neoplasms (metabolism, pathology)
• Caspase 3 (metabolism)
• Cell Line, Tumor
• Gene Expression Regulation, Neoplastic (drug effects)
• Glioblastoma (metabolism, pathology)
• Humans
• Interleukin-8 (metabolism)
• Mice
• Mice, Nude
• Oligopeptides (pharmacology)
• Protein Binding
• Signal Transduction (drug effects)
• Transcription Factor RelA (genetics, metabolism)
• Transplantation, Heterologous
• Ubiquitination (drug effects)
• rho GTP-Binding Proteins (genetics, metabolism)