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Title: Toll-like receptor 4 promotes angiogenesis in pancreatic cancer via PI3K/AKT signaling

Abstract

Deregulation of Toll-like receptor 4 (TLR4) is closely associated with the progression of various types of cancers, but its role in pancreatic carcinogenesis is unclear. This study aimed to investigate the role of TLR4 in the angiogenesis of pancreatic cancer and the underlying molecular mechanisms. The culture supernatant (conditioned medium) of PANC-1 cells after appropriate treatment was used for the treatment of HUVECs. The proliferation, migration and tube formation of HUVECs were assessed by MTT, Transwell and Matrigel, respectively. In pancreatic cancer tissues, TLR4, VEGF and CD31 were upregulated as determined by immunohistochemistry and the expression of TLR4 and VEGF was positively correlated with microvessel density as detected by CD31 staining. Activation of TLR4 signaling by LPS in PANC-1 cells resulted in increased VEGF and phosphorylation of AKT, which were abolished by TLR4 silencing with siRNA and PI3K/AKT signaling inhibitor LY294002. The conditioned medium from PANC-1 cells treated with LY294002 or transfected with TRL4 siRNA reduced the proliferation, migration and tube formation of HUVECs. In contrast, the conditioned medium from PANC-1 cells treated with LPS stimulated the proliferation, migration and tube formation of HUVECs, which was however significantly inhibited by pretreatment of PANC-1 cells with LY294002 or transfection with TRL4more » siRNA. Our findings suggest TLR4 may promote angiogenesis in pancreatic cancer by activating the PI3K/AKT signaling pathway to induce VEGF expression.« less

Authors:
;  [1];  [2];  [2]; ; ;  [3]
  1. Department of Gastroenterology, Lianyungang Ganyu People’s Hospital, Ganyu, Jiangsu (China)
  2. Department of Gastroenterology, Huadong Hospital, Fudan University, Shanghai (China)
  3. Department of Gastroenterology, Changhai Hospital, The Second Military Medical University, Shanghai (China)
Publication Date:
OSTI Identifier:
22649764
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 347; Journal Issue: 2; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ANGIOGENESIS; CARCINOGENESIS; CATTLE; DENSITY; DMSO; ENZYME IMMUNOASSAY; ENZYMES; GROWTH FACTORS; LIPOPOLYSACCHARIDES; NEOPLASMS; PANCREAS; PHOSPHORYLATION; PLANT GROWTH; PLANT TISSUES; RECEPTORS; SIGNALS; VEINS

Citation Formats

Sun, Yunliang, Wu, Congshan, Ma, Jianxia, E-mail: yz_mjx@163.com, Yang, Yu, Man, Xiaohua, Wu, Hongyu, and Li, Shude. Toll-like receptor 4 promotes angiogenesis in pancreatic cancer via PI3K/AKT signaling. United States: N. p., 2016. Web. doi:10.1016/J.YEXCR.2016.07.009.
Sun, Yunliang, Wu, Congshan, Ma, Jianxia, E-mail: yz_mjx@163.com, Yang, Yu, Man, Xiaohua, Wu, Hongyu, & Li, Shude. Toll-like receptor 4 promotes angiogenesis in pancreatic cancer via PI3K/AKT signaling. United States. doi:10.1016/J.YEXCR.2016.07.009.
Sun, Yunliang, Wu, Congshan, Ma, Jianxia, E-mail: yz_mjx@163.com, Yang, Yu, Man, Xiaohua, Wu, Hongyu, and Li, Shude. 2016. "Toll-like receptor 4 promotes angiogenesis in pancreatic cancer via PI3K/AKT signaling". United States. doi:10.1016/J.YEXCR.2016.07.009.
@article{osti_22649764,
title = {Toll-like receptor 4 promotes angiogenesis in pancreatic cancer via PI3K/AKT signaling},
author = {Sun, Yunliang and Wu, Congshan and Ma, Jianxia, E-mail: yz_mjx@163.com and Yang, Yu and Man, Xiaohua and Wu, Hongyu and Li, Shude},
abstractNote = {Deregulation of Toll-like receptor 4 (TLR4) is closely associated with the progression of various types of cancers, but its role in pancreatic carcinogenesis is unclear. This study aimed to investigate the role of TLR4 in the angiogenesis of pancreatic cancer and the underlying molecular mechanisms. The culture supernatant (conditioned medium) of PANC-1 cells after appropriate treatment was used for the treatment of HUVECs. The proliferation, migration and tube formation of HUVECs were assessed by MTT, Transwell and Matrigel, respectively. In pancreatic cancer tissues, TLR4, VEGF and CD31 were upregulated as determined by immunohistochemistry and the expression of TLR4 and VEGF was positively correlated with microvessel density as detected by CD31 staining. Activation of TLR4 signaling by LPS in PANC-1 cells resulted in increased VEGF and phosphorylation of AKT, which were abolished by TLR4 silencing with siRNA and PI3K/AKT signaling inhibitor LY294002. The conditioned medium from PANC-1 cells treated with LY294002 or transfected with TRL4 siRNA reduced the proliferation, migration and tube formation of HUVECs. In contrast, the conditioned medium from PANC-1 cells treated with LPS stimulated the proliferation, migration and tube formation of HUVECs, which was however significantly inhibited by pretreatment of PANC-1 cells with LY294002 or transfection with TRL4 siRNA. Our findings suggest TLR4 may promote angiogenesis in pancreatic cancer by activating the PI3K/AKT signaling pathway to induce VEGF expression.},
doi = {10.1016/J.YEXCR.2016.07.009},
journal = {Experimental Cell Research},
number = 2,
volume = 347,
place = {United States},
year = 2016,
month =
}
  • Highlights: Black-Right-Pointing-Pointer Hypoxic stress-induced TLR4 expression is mediated by PI3K/Akt in macrophages. Black-Right-Pointing-Pointer PI3K/Akt regulated HIF-1 activation leading to TLR4 expression. Black-Right-Pointing-Pointer p38 mitogen-activated protein kinase was not involved in TLR4 expression by hypoxic stress. Black-Right-Pointing-Pointer Sulforaphane suppressed hypoxia-mediated TLR4 expression by inhibiting PI3K/Akt. -- Abstract: Toll-like receptors (TLRs) play critical roles in triggering immune and inflammatory responses by detecting invading microbial pathogens and endogenous danger signals. Increased expression of TLR4 is implicated in aggravated inflammatory symptoms in ischemic tissue injury and chronic diseases. Results from our previous study showed that TLR4 expression was upregulated by hypoxic stress mediated bymore » hypoxia-inducible factor-1 (HIF-1) at a transcriptional level in macrophages. In this study, we further investigated the upstream signaling pathway that contributed to the increase of TLR4 expression by hypoxic stress. Either treatment with pharmacological inhibitors of PI3K and Akt or knockdown of Akt expression by siRNA blocked the increase of TLR4 mRNA and protein levels in macrophages exposed to hypoxia and CoCl{sub 2}. Phosphorylation of Akt by hypoxic stress preceded nuclear accumulation of HIF-1{alpha}. A PI3K inhibitor (LY294002) attenuated CoCl{sub 2}-induced nuclear accumulation and transcriptional activation of HIF-1{alpha}. In addition, HIF-1{alpha}-mediated upregulation of TLR4 expression was blocked by LY294002. Furthermore, sulforaphane suppressed hypoxia- and CoCl{sub 2}-induced upregulation of TLR4 mRNA and protein by inhibiting PI3K/Akt activation and the subsequent nuclear accumulation and transcriptional activation of HIF-1{alpha}. However, p38 was not involved in HIF-1{alpha} activation and TLR4 expression induced by hypoxic stress in macrophages. Collectively, our results demonstrate that PI3K/Akt contributes to hypoxic stress-induced TLR4 expression at least partly through the regulation of HIF-1 activation. These reveal a novel mechanism for regulation of TLR4 expression upon hypoxic stress and provide a therapeutic target for chronic diseases related to hypoxic stress.« less
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