title: Glucose-regulated protein 78 silencing down-regulates vascular endothelial growth factor/vascular endothelial growth factor receptor 2 pathway to suppress human colon cancer tumor growth.
abstract: BACKGROUND
  Up to 20% of colorectal cancer (CRC) is diagnosed with distant metastasis. The combination of chemotherapy with anti-vascular endothelial growth factor (VEGF) antibody can improve patient survival. Glucose-regulated protein 78 (GRP78) has an important role in cancer progression, but little is known about its role in VEGF production in CRC. The aim of this study was to explore the mechanism of GRP78 in two human colon cancer cell lines.
  
  
  METHODS
  We first checked the expression of GRP78 in human normal and colon cancer tissues and two colon cancer cell lines. Glucose-regulated protein 78 was knocked down using GRP78 small interfering RNA (siRNA) in HT29 and DLD-1 cells. We examined knockdown cells by the cell growth kinetics in vitro and tumor growth rate in vivo, respectively. We also investigated the effect of GRP78 siRNA on the expression of hypoxia inducible factor (HIF-1α), VEGF, and VEGF receptor 2 (VEGFR2).
  
  
  RESULTS
  Compared with their adjacent normal tissue, we detected high expression levels of GRP78 of surgically removed colon cancer tissues. Using GRP78 siRNA, we reduced the expression of GRP78 in HT29 and DLD-1 cells. The GRP78 knockdown cells had a lower proliferation rate with fewer colony-forming units in vitro and produced smaller tumors in vivo. In dissecting the mechanism underlying the reduced cell growth, we found that the down-regulation of GRP78 decreased the production of HIF-1α, VEGF, and VEGFR2 and suppressed angiogenesis.
  
  
  CONCLUSIONS
  Silencing GRP78 not only inhibits tumor, but also decreases the expression of VEGF and VEGFR2. Collectively, therapy targeting for GRP78 may inhibit the formation of colon cancer tumors via the HIF-1α/VEGF/VEGFR2 pathway.
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China; Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China; Division of General Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan, Republic of China.
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Kuo
authors.forename: Chin-Sheng
authors.initials: CS
authors.lastname: Hung
authors.forename: Wei-Yu
authors.initials: WY
authors.lastname: Chen
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Chang
authors.forename: Po-Li
authors.initials: PL
authors.lastname: Wei
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000818:Animals; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015536:Down-Regulation / Q000502:physiology; D000091342:Endoplasmic Reticulum Chaperone BiP; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D019073:HT29 Cells; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C497442:HIF1A protein, human; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Angiogenesis; Colon cancer; Glucose-regulated protein 78; Vascular endothelial growth factor