NF-κB p65 Overexpression Promotes Bladder Cancer Cell Migration via FBW7-Mediated Degradation of RhoGDIα Protein.

Abstract

BACKGROUND:

Since invasive bladder cancer (BC) is one of the most lethal urological malignant tumors worldwide, understanding the molecular mechanisms that trigger the migration, invasion, and metastasis of BC has great significance in reducing the mortality of this disease. Although RelA/p65, a member of the NF-kappa B transcription factor family, has been reported to be upregulated in human BCs, its regulation of BC motility and mechanisms have not been explored yet.

METHODS:

NF-κBp65 expression was evaluated in N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced high invasive BCs by immunohistochemistry staining and in human BC cell lines demonstrated by Western Blot. The effects of NF-κBp65 knockdown on BC cell migration and invasion, as well as its regulated RhoGDIα and FBW7, were also evaluated in T24T cells by using loss- and gain-function approaches. Moreover, the interaction of FBW7 with RhoGDIα was determined with immunoprecipitation assay, while critical role of ubiquitination of RhoGDIα by FBW7 was also demonstrated in the studies.

RESULTS:

p65 protein was remarkably upregulated in the BBN-induced high invasive BCs and in human BC cell lines. We also observed that p65 overexpression promoted BC cell migration by inhibiting RhoGDIα expression. The regulatory effect of p65 on RhoGDIα expression is mediated by its upregulation of FBW7, which specifically interacted with RhoGDIα and promoted RhoGDIα ubiquitination and degradation. Mechanistic studies revealed that p65 stabilizing the E3 ligase FBW7 protein was mediated by its attenuating pten mRNA transcription.

CONCLUSIONS:

We demonstrate that p65 overexpression inhibits pten mRNA transcription, which stabilizes the protein expression of ubiquitin E3 ligase FBW7, in turn increasing the ubiquitination and degradation of RhoGDIα protein and finally promoting human BC migration. The novel identification of p65/PTEN/FBW7/RhoGDIα axis provides a significant insight into understanding the nature of BC migration, further offering a new theoretical support for cancer therapy.

• Authors: Junlan Zhu, Yang Li, Caiyi Chen, Jiugao Ma, Wenrui Sun, Zhongxian Tian, Jingxia Li, Jiheng Xu, Claire S Liu, Dongyun Zhang, Chuanshu Huang, Haishan Huang
• Journal: Neoplasia (New York, N.Y.) (Neoplasia) Vol. 19 Issue 9 Pg. 672-683 (Sep 2017) ISSN: 1476-5586 [Electronic] United States
• PMID: 28772241 (Publication Type: Journal Article)
• Copyright: Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical References

• F-Box-WD Repeat-Containing Protein 7
• FBXW7 protein, human
• Transcription Factor RelA
• rho Guanine Nucleotide Dissociation Inhibitor alpha

Topics

• Animals
• Cell Line, Tumor
• Cell Movement (genetics)
• Disease Models, Animal
• F-Box-WD Repeat-Containing Protein 7 (metabolism)
• Gene Expression
• Genes, Reporter
• Heterografts
• Humans
• Mice
• Mice, Knockout
• Protein Binding
• Protein Stability
• Transcription Factor RelA (genetics, metabolism)
• Urinary Bladder Neoplasms (genetics, metabolism, pathology)
• rho Guanine Nucleotide Dissociation Inhibitor alpha (metabolism)