过氧化物酶 1 通过 TLR4 依赖性激活 HIF-1α 刺激血管内皮细胞表达 VEGF。

Peroxiredoxin 1 stimulates endothelial cell expression of VEGF via TLR4 dependent activation of HIF-1α.

机构信息

Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, New York, United States of America.

出版信息

PLoS One. 2012;7(11):e50394. doi: 10.1371/journal.pone.0050394. Epub 2012 Nov 21.

Abstract

Chronic inflammation leads to the formation of a pro-tumorigenic microenvironment that can promote tumor development, growth and differentiation through augmentation of tumor angiogenesis. Prostate cancer (CaP) risk and prognosis are adversely correlated with a number of inflammatory and angiogenic mediators, including Toll-like receptors (TLRs), NF-κB and vascular endothelial growth factor (VEGF). Peroxiredoxin 1 (Prx1) was recently identified as an endogenous ligand for TLR4 that is secreted from CaP cells and promotes inflammation. Inhibition of Prx1 by CaP cells resulted in reduced expression of VEGF, diminished tumor vasculature and retarded tumor growth. The mechanism by which Prx1 regulates VEGF expression in normoxic conditions was investigated in the current study. Our results show that incubation of mouse vascular endothelial cells with recombinant Prx1 caused increases in VEGF expression that was dependent upon TLR4 and required hypoxia inducible factor-1 (HIF-1) interaction with the VEGF promoter. The induction of VEGF was also dependent upon NF-κB; however, NF-κB interaction with the VEGF promoter was not required for Prx1 induction of VEGF suggesting that NF-κB was acting indirectly to induce VEGF expression. The results presented here show that Prx1 stimulation increased NF-κB interaction with the HIF-1α promoter, leading to enhanced promoter activity and increases in HIF-1α mRNA levels, as well as augmented HIF-1 activity that resulted in VEGF expression. Prx1 induced HIF-1 also promoted NF-κB activity, suggesting the presence of a positive feedback loop that has the potential to perpetuate Prx1 induction of angiogenesis. Strikingly, inhibition of Prx1 expression in CaP was accompanied with reduced expression of HIF-1α. The combined findings of the current study and our previous study suggest that Prx1 interaction with TLR4 promotes CaP growth potentially through chronic activation of tumor angiogenesis.

摘要

慢性炎症导致肿瘤发生前的微环境形成,该微环境可通过促进肿瘤血管生成来促进肿瘤的发展、生长和分化。前列腺癌(CaP)的风险和预后与许多炎症和血管生成介质密切相关,包括 Toll 样受体(TLRs)、NF-κB 和血管内皮生长因子(VEGF)。过氧化物还原酶 1(Prx1)最近被鉴定为 TLR4 的内源性配体,它由 CaP 细胞分泌,并促进炎症。CaP 细胞中 Prx1 的抑制导致 VEGF 的表达减少、肿瘤血管减少和肿瘤生长减缓。在本研究中,研究了 Prx1 在常氧条件下调节 VEGF 表达的机制。我们的结果表明,用重组 Prx1 孵育小鼠血管内皮细胞会导致 VEGF 表达增加,这种增加依赖于 TLR4,并需要缺氧诱导因子-1(HIF-1)与 VEGF 启动子相互作用。VEGF 的诱导也依赖于 NF-κB;然而,Prx1 诱导 VEGF 表达并不需要 NF-κB 与 VEGF 启动子相互作用,这表明 NF-κB 是间接作用于诱导 VEGF 表达。这里呈现的结果表明,Prx1 刺激增加了 NF-κB 与 HIF-1α 启动子的相互作用,导致启动子活性增强和 HIF-1α mRNA 水平增加,并增强了 HIF-1 活性,从而导致 VEGF 表达。Prx1 诱导的 HIF-1 也促进了 NF-κB 活性,这表明存在一个正反馈回路,有可能使 Prx1 诱导的血管生成持续存在。引人注目的是,CaP 中 Prx1 表达的抑制伴随着 HIF-1α 的表达减少。本研究和我们之前的研究结果表明,Prx1 与 TLR4 的相互作用促进了 CaP 的生长,可能是通过慢性激活肿瘤血管生成。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/2c9c/3503895/fdd94d5f4877/pone.0050394.g001.jpg

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