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Exp Cell Res. 2014 Apr 15;323(1):155-64. doi: 10.1016/j.yexcr.2014.02.020. Epub 2014 Feb 25.

Interleukin-8 promotes canine hemangiosarcoma growth by regulating the tumor microenvironment.

Author information

1
Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA. Electronic address: jhkim@umn.edu.
2
Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
3
Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
4
Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
5
Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA; Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA.
6
Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA. Electronic address: modiano@umn.edu.

Abstract

Interleukin-8 (IL-8) gene expression is highly up-regulated in canine hemangiosarcoma (HSA); however, its role in the pathogenesis of this disease is unknown. We investigated the expression of IL-8 in canine HSA tissues and cell lines, as well and the effects of IL-8 on canine HSA in vitro, and in vivo using a mouse xenograft model for the latter. Constitutive expression of IL-8 mRNA, IL-8 protein, and IL-8 receptor were variable among different tumor samples and cell lines, but they showed stable steady states in each cell line. Upon the addition of IL-8, HSA cells showed transient intracellular calcium fluxes, suggesting that their IL-8 receptors are functional and that IL-8 binding activates relevant signaling pathways. Yet, neither addition of exogenous IL-8 nor blockade of endogenous IL-8 by neutralizing anti-IL-8 antibody (α-IL-8 Ab) affected HSA cell proliferation or survival in vitro. To assess potential effects of IL-8 in other tumor constituents, we stratified HSA cell lines and whole tumor samples into "IL-8 high" and "IL-8 low" groups. Genome-wide gene expression profiling showed that samples in the "IL-8 high" tumor group were enriched for genes associated with a "reactive microenvironment," including activation of coagulation, inflammation, and fibrosis networks. Based on these findings, we hypothesized that the effects of IL-8 on these tumors were mostly indirect, regulating interactions with the microenvironment. This hypothesis was supported by in vivo xenograft experiments where survival and engraftment of tumor cells was inhibited by administration of neutralizing α-IL-8 Ab. Together, our results suggest that IL-8 contributes to establishing a permissive microenvironment during the early stages of tumorigenesis in HSA.

KEYWORDS:

Canine; Gene expression profiling; Hemangiosarcoma; Interleukin-8; Tumor microenvironment

PMID:
24582862
PMCID:
PMC4256199
DOI:
10.1016/j.yexcr.2014.02.020
[Indexed for MEDLINE]
Free PMC Article
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