title: Effects of repeated in vivo inhalant nitrite exposure on gene expression in mouse liver and lungs.
abstract: Exposure to inhalant organic nitrites (drugs of abuse commonly known as "poppers") has been reported to enhance tumor growth in mice, but the mechanism is not fully defined. This study examined the effect of repeated in vivo nitrite exposures on gene expression in the mouse liver and lungs using a gene array panel of 94 cancer- and angiogenesis-related genes. Using 2-fold change as a threshold criterion, repeated nitrite exposure was found to alter the expression of 65 and 23 genes in the liver and lungs, respectively. Six genes were significantly upregulated (p<or=0.05), viz., those encoding VEGF, VEGFD (vascular endothelial growth factor A and D, respectively) in the lungs and FGF1, FGF4 (fibroblast growth factor 1 and 4, respectively), Hsp70 (heat shock 70kDa protein 4), and PF4 (platelet factor 4) in the liver. mRNA encoding HO-1 (heme oxygenase-1) and Smad7 were marginally (p=0.057) stimulated in the liver. Follow-up studies in the liver revealed significant nitrite-induced expression of VEGF protein and mRNA. Immuno-staining of liver slices revealed that the increased hepatic VEGF expression resided mainly in hepatocytes. Stimulation of hepatic VEGF expression by ISBN was not different in endothelial nitric oxide synthase (eNOS) knockout vs. wild-type mice. In conclusion, multiple exposures to inhalant nitrite appeared to cause alteration in the expression of a number of genes relating to cancer and angiogenesis, including VEGF. eNOS presence did not appear to be essential for nitrite-induced VEGF expression. These studies demonstrate that in vivo exposure to inhalant nitrites results in changes in the angiogenesis cascade.
authors.affiliation: Department of Pharmaceutical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA.
authors.forename: Doanh C
authors.initials: DC
authors.lastname: Tran
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Brazeau
authors.forename: Peter A
authors.initials: PA
authors.lastname: Nickerson
authors.forename: Ho-Leung
authors.initials: HL
authors.lastname: Fung
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D015870:Gene Expression / Q000187:drug effects*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D009573:Nitrites / Q000008:administration & dosage / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D020030:Nitric Oxide Donors; D009573:Nitrites; D042461:Vascular Endothelial Growth Factor A; D019001:Nitric Oxide Synthase