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

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.

Aberrant Retinoblastoma (RB)-E2F Transcriptional Regulation Defines Molecular Phenotypes of Osteosarcoma

“…OSCA-8, OSCA-32, and OSCA-40 cells were modified to stably express GFP and firefly luciferase (Luc) for in vivo experiments (18). Fluorescence in situ hybridization was used to determine the number of GFP/Luc copies in the cell lines.…”

Evaluation of Serum Interleukin-8 (CXCL8) Concentrations in Tumor Bearing Dogs

“…Several studies affirm that the highly selective pro-inflammatory and angiogenic chemokine Interleukin-8 (IL-8 or CXCL8) is involved in this process and therefore, is a potential tumor marker (Yuan et al, 2005;Kim et al, 2014;Raman et al, 2007;Strieter et al, 2004;Koch et al, 1992;Baggiolini et al, 1989;Addison et al, 2000). However, research into CXCL8 in veterinary medicine is scarce.…”

“…Although the major production of CXCL8 occurs locally as an adaptive response of cancer cells to withstand environmental or chemical stresses (Kim et al, 2014;Raman et al, 2007;Desbaillets et al, 1997;Shi et al, 2001), its concentration has been found to be also elevated in the blood of human and canine cancer patients (Yokoe et al, 1996;Ueda et al, 1994;Veltri et al, 1999;Gelaleti et al, 2012;De Andrés et al, 2013;Konno et al, 2003;Ugurel et al, 2001;Ren et al, 2003;Benoy et al, 2004;Lokshin et al, 2006). On the one hand, cells within the tumor tissue are known to secrete CXCL8 that may partly escape the tumor environment and reach the bloodstream through the vast amount of blood vessels that usually nourish a tumor.…”

“…Similarly, a more recent study by De Andrés et al (2013) supported this finding by assessing local and serum CXCL8 in benign and malignant mammary gland tumors (De Andrés et al, 2013). A study by Kim et al (2014) on local CXCL8 expression in canine hemangiosarcoma suggested that the effect of CXCL8 is mostly indirect and that its production is part of an adaptive mechanism used by tumor cells to modulate their microenvironment (Kim et al, 2014).…”

“…Blocking the angiogenic activity of CXCL8 has already been effective in murine models and the development of humanized monoclonal antibodies has enabled several investigations to determine positive effects when suppressing CXCL8 signaling in human tumors (Heidemann et al, 2003;Waugh and Wilson, 2008;Kim et al, 2014). Even though most studies assure the involvement of CXCL8 in tumorigenesis, the extent of its influence remains controversial (Yao et al, 2007).…”