title: Blocking heme oxygenase-1 by zinc protoporphyrin reduces tumor hypoxia-mediated VEGF release and inhibits tumor angiogenesis as a potential therapeutic agent against colorectal cancer.
abstract: BACKGROUND
  Hypoxia in tumor niche is one of important factors to start regeneration of blood vessels, leading to increase survival, proliferation, and invasion in cancer cells. Under hypoxia microenvironment, furthermore, steadily increased hypoxia-inducible factor -1α (HIF-1α) is observed, and can increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis. Zinc protoporphyrin (ZnPP), a heme oxygenase-1 (HO-1) inhibitor, is potential to inhibit tumor proliferation and progression. However, the mechanism of ZnPP in inhibition of tumor is not completely clear. We hypothesize that ZnPP may modulate HIF-1α through inhibiting HO-1, and then inhibit angiogenesis and tumor progression. This study aimed to dissect the mechanism of ZnPP in tumor suppression.
  
  
  RESULTS
  We observed the amount of VEGF was increased in the sera of the colorectal cancer (CRC) patients (n = 34, p < 0.05). Furthermore, increased VEGF expression was also measured in colorectal cancer cells, HCT-15, culturing under mimicking hypoxic condition. It suggested that hypoxia induced VEGF production from cancer cells. VEGF production was significantly reduced from HCT-15 cells after exposure to HIF-1α inhibitor KC7F2, suggesting that HIF-1α regulated VEGF production. Moreover, we observed that the HO-1 inhibitor ZnPP inhibited the expressions of HIF-1α and VEGF coupled with cell proliferations of HCT-15 cells, suggesting that ZnPP blocked HIF-1α expression, and then inhibited the consequent VEGF production. In the xenograft model, we also observed that the animals exposed to ZnPP displayed much smaller tumor nodules and less degree of angiogenesis with decreased expression of the angiogenesis marker, αvβ3 integrin, compared to that in normal control.
  
  
  CONCLUSIONS
  This study demonstrated that VEGF level in serum was elevated in the patients with CRC. The HO-1 inhibitor, ZnPP, possessed the properties of anti-tumor agent by decreasing HIF-1α levels, blocking VEGF production, impairing tumor angiogenesis, and inhibiting tumor growth.
authors.affiliation: Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan.|Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chun-Chia
authors.initials: CC
authors.lastname: Cheng
authors.affiliation: Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan.
authors.forename: Siao-Syun
authors.initials: SS
authors.lastname: Guan
authors.affiliation: Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan.
authors.forename: Hao-Jhih
authors.initials: HJ
authors.lastname: Yang
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan.|Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chun-Chao
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan, Taiwan.
authors.forename: Tsai-Yueh
authors.initials: TY
authors.lastname: Luo
authors.affiliation: Graduate Institute of Medical Sciences, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. js.chang@tmu.edu.tw.
authors.forename: Jungshan
authors.initials: J
authors.lastname: Chang
authors.affiliation: Division of Gastroenterology, Cheng Hsin General Hospital, Taipei, Taiwan. aisheng49@gmail.com.|Nursing Department, Kang-Ning University, Taipei, Taiwan. aisheng49@gmail.com.
authors.forename: Ai-Sheng
authors.initials: AS
authors.lastname: Ho
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000201:enzymology; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D000860:Hypoxia; D008665:Metalloporphyrins / Q000494:pharmacology*; D051379:Mice; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D008665:Metalloporphyrins; D009363:Neoplasm Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C017802:zinc hematoporphyrin; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1
references.citation: Biochem Pharmacol. 2013 Jun 1;85(11):1611-8
references.pmid: 23523860
references.citation: Mediators Inflamm. 2013;2013:354087
references.pmid: 23431240
references.citation: Curr Cancer Drug Targets. 2014;14(4):337-47
references.pmid: 24655000
references.citation: BMC Cancer. 2014;14:436
references.pmid: 24927633
references.citation: World J Gastroenterol. 2014 Jul 14;20(26):8572-82
references.pmid: 25024611
references.citation: Curr Drug Targets. 2010 Dec;11(12):1551-70
references.pmid: 20704546
references.citation: Med Phys. 2011 Dec;38(12):6347-50
references.pmid: 22149817
references.citation: PLoS One. 2014;9(8):e105994
references.pmid: 25162226
references.citation: Transl Res. 2014 Dec;164(6):468-76
references.pmid: 25063314
references.citation: Oncotarget. 2014 Nov 30;5(22):11452-63
references.pmid: 25360516
references.citation: World J Gastroenterol. 2015 Mar 14;21(10):2937-48
references.pmid: 25780291
references.citation: J Biomed Sci. 2015;22:22
references.pmid: 25885228
references.citation: Biochem Biophys Res Commun. 1999 Dec 29;266(3):718-22
references.pmid: 10603309
references.citation: Biochem Biophys Res Commun. 2000 Feb 16;268(2):652-6
references.pmid: 10679259
references.citation: Clin Cancer Res. 2000 May;6(5):1900-8
references.pmid: 10815914
references.citation: Cancer Res. 2000 Aug 1;60(15):4010-5
references.pmid: 10945599
references.citation: J Pharmacol Exp Ther. 2000 Sep;294(3):1009-16
references.pmid: 10945853
references.citation: Therapie. 2001 Sep-Oct;56(5):495-9
references.pmid: 11806285
references.citation: Am Surg. 2003 Jan;69(1):3-10
references.pmid: 12575772
references.citation: Br J Cancer. 2003 Mar 24;88(6):902-9
references.pmid: 12644828
references.citation: Cancer Res. 2003 Jul 1;63(13):3567-74
references.pmid: 12839943
references.citation: J Clin Invest. 1986 Feb;77(2):335-9
references.pmid: 3511095
references.citation: J Biol Chem. 1997 Feb 28;272(9):5375-81
references.pmid: 9038135
references.citation: Proc Natl Acad Sci U S A. 1997 Jul 22;94(15):8104-9
references.pmid: 9223322
references.citation: Jpn J Clin Oncol. 2005 Apr;35(4):207-13
references.pmid: 15845570
references.citation: Cancer Lett. 2005 Jul 28;225(2):297-304
references.pmid: 15978334
references.citation: J Neurooncol. 2006 Jul;78(3):233-47
references.pmid: 16612574
references.citation: Int J Oncol. 2007 Jan;30(1):45-54
references.pmid: 17143511
references.citation: Radiology. 2007 Mar;242(3):751-8
references.pmid: 17325064
references.citation: Oncology (Williston Park). 2007 Aug;21(9 Suppl 3):21-4
references.pmid: 17927027
references.citation: J Appl Physiol (1985). 2008 Mar;104(3):795-802
references.pmid: 18202169
references.citation: Pharmacol Rev. 2008 Mar;60(1):79-127
references.pmid: 18323402
references.citation: Int J Cancer. 2008 Sep 15;123(6):1269-77
references.pmid: 18566988
references.citation: Mol Cancer. 2009;8:37
references.pmid: 19508729
references.citation: Cancer Res. 2009 Oct 15;69(20):8017-24
references.pmid: 19808972
references.citation: J Biol Chem. 2009 Dec 25;284(52):36302-11
references.pmid: 19850937
references.citation: Int J Cancer. 2012 Feb 1;130(3):716-27
references.pmid: 21413014
references.citation: PLoS One. 2010;5(12):e15048
references.pmid: 21179202
references.citation: Chin Med J (Engl). 2012 Apr;125(7):1310-5
references.pmid: 22613607
references.citation: Invest Ophthalmol Vis Sci. 2012 Oct;53(10):6541-56
references.pmid: 22661484
references.citation: Cell Oncol (Dordr). 2012 Dec;35(6):461-71
references.pmid: 23055342
references.citation: Cell Rep. 2014 Jan 16;6(1):155-67
references.pmid: 24388748