Decreased expression of CHIP leads to increased angiogenesis via VEGF-VEGFR2 pathway and poor prognosis in human renal cell carcinoma.

Chao Sun,Qing-Hua Liu,Jin Bai,Mei-Lin Shi,Zhen-Qiang Pan,Jun-Nian Zheng,Hai-Long Li,Hai-Rong Chen

doi:10.1038/srep09774

Abstract

CHIP (c-terminal Hsp70-interacting protein) is an E3 ligase which may play different roles in different cancers. The elucidation of the VHL-HIF-1α(hypoxia inducible factor-1α)-VEGF (vascular endothelial growth factor) pathway has led to the development of targeted therapy in renal cell carcinoma (RCC). However, little is known about the role of CHIP and the relationship between CHIP and VEGF-VEGFR2 (VEGF receptor 2) pathway in RCC. In this study, we found that the expression of CHIP was downregulated and significantly correlated with pT status (P = 0.022) and TNM stage (P = 0.022) in 304 RCC and 35 normal renal tissues using tissue microarray. Moreover, low expression of CHIP is a strong and independent negative prognostic value for RCC. In vitro, CHIP negatively regulated RCC cell migration, invasion and angiogenesis. In addition, ELISA tests showed that restoration of CHIP inhibited, while knockdown promoted, the secreted level of VEGF. Furthermore, western blot indicated that the VEGFR2 protein level was reduced after CHIP overexpression. Our findings demonstrate for the first time that CHIP may be involved in RCC angiogenesis through regulating VEGF secretion and expression of VEGFR2. CHIP may serve as promising prognostic biomarker of angiogenesis and may constitute a potential therapeutic target in RCC.

Highlights

renal cell carcinoma (RCC) accounts for approximately 3% of all malignancies, and the incidence of RCC is increasing by a rate of approximately 2.5% each year[1]
To investigate whether CHIP expression is changed in RCC, IHC staining was performed in our established tissue microarray (TMA) slides (Fig. 1A)
Positive CHIP staining was recorded in 94.1% (32/34) and 51.0% (155/304) of the biopsies in normal renal tissues (NRT) and RCC tissue, respectively (Fig. 1B).We found that CHIP staining was mainly localized in the cytoplasm and the expression of CHIP was significant lower in the carcinoma tissues than the NRT (P = 0.0001)

Summary

Introduction

RCC accounts for approximately 3% of all malignancies, and the incidence of RCC is increasing by a rate of approximately 2.5% each year[1]. In the absence of functional pVHL, HIF-1α accumulates, which causes downstream upregulation of a number of pro-angiogenic factors, including the VEGF3. VEGF exerts its biologic effect through interaction with receptors present on the cell surface. These transmembrane tyrosine kinase receptors include VEGFR1, VEGFR2 and VEGFR3. VEGF receptors have been identified on the surface of renal cancer cells, suggesting that VEGF may augment RCC tumor growth through an autocrine loop[6]. We tested the hypothesis that CHIP regulates cell migration, invasion and angiogenesis by inhibiting VEGF signaling pathway in RCC. We further investigated the role of CHIP in RCC cell migration, invasion and angiogenesis. We studied the relation between CHIP expression and the secreted level of VEGF and VEGFR2 protein expression

Methods

Results

Conclusion