Decreased Autocrine EGFR Signaling in Metastatic Breast Cancer Cells Inhibits Tumor Growth in Bone and Mammary Fat Pad

Abstract

Breast cancer metastasis to bone triggers a vicious cycle of tumor growth linked to osteolysis. Breast cancer cells and osteoblasts express the epidermal growth factor receptor (EGFR) and produce ErbB family ligands, suggesting participation of these growth factors in autocrine and paracrine signaling within the bone microenvironment. EGFR ligand expression was profiled in the bone metastatic MDA-MB-231 cells (MDA-231), and agonist-induced signaling was examined in both breast cancer and osteoblast-like cells. Both paracrine and autocrine EGFR signaling were inhibited with a neutralizing amphiregulin antibody, PAR34, whereas shRNA to the EGFR was used to specifically block autocrine signaling in MDA-231 cells. The impact of these was evaluated with proliferation, migration and gene expression assays. Breast cancer metastasis to bone was modeled in female athymic nude mice with intratibial inoculation of MDA-231 cells, and cancer cell-bone marrow co-cultures. EGFR knockdown, but not PAR34 treatment, decreased osteoclasts formed in vitro (p<0.01), reduced osteolytic lesion tumor volume (p<0.01), increased survivorship in vivo (p<0.001), and resulted in decreased MDA-231 growth in the fat pad (p<0.01). Fat pad shEGFR-MDA-231 tumors produced in nude mice had increased necrotic areas and decreased CD31-positive vasculature. shEGFR-MDA-231 cells also produced decreased levels of the proangiogenic molecules macrophage colony stimulating factor-1 (MCSF-1) and matrix metalloproteinase 9 (MMP9), both of which were decreased by EGFR inhibitors in a panel of EGFR-positive breast cancer cells. Thus, inhibiting autocrine EGFR signaling in breast cancer cells may provide a means for reducing paracrine factor production that facilitates microenvironment support in the bone and mammary gland.

EGFR and microvessel density in canine malignant mammary tumours

“…The link between EGFR and MVD was a subject of study in human breast cancer, with some researchers describing correlations with increased risk of metastasis and shorter overall survival, although with no consistent findings among different authors (Fox et al, 1994;Weidner and Gasparini, 1994;Nieto et al, 2007;Nickerson et al, 2012). The higher expression of EGFR in the current study was significantly associated with a high microvessel density.…”

“…The link between EGFR and MVD was studied in several human tumours (Perrotte et al, 1999;Baumann and Krause, 2004;Iivanainen et al, 2009;Diaz et al, 2010;Jin et al, 2011), including breast cancer (Fox et al, 1994;Weidner and Gasparini, 1994;Nieto et al, 2007;Nickerson et al, 2012). In CMT, MVD accessed by CD31 immunoexpression was studied by some authors (Graham and Myers, 1999;Restucci et al, 2000;Lavalle et al, 2009;Queiroga et al, 2011), and EGFR immunoexpression was also described (Gama et al, 2009;Guimarães et al, 2013;Kim et al, 2013).…”

“…High levels of angiogenic factors and histologic evidence of increased tumour neovascularization are considered to be associated with malignancy and prognosis in human breast cancer (Hanahan and Folkman, 1996;Locopo et al, 1998;Gasparini, 2000Gasparini, , 2001Leek, 2001) and different studies have indicated similar results in CMT (Restucci et al, 2000;Lavalle et al, 2009;Queiroga et al, 2011). EGFR signaling and angiogenesis have been independently evaluated as targets for therapy in human studies (Fox et al, 1994;Weidner and Gasparini, 1994;Nieto et al, 2007;Nickerson et al, 2012) and several factors support the potential interaction between them: tumour cells can be stimulated in a paracrine manner by growth factors; endothelial cells and tumour cells can stimulate each other's growth in the tumour microenvironment (Rowe et al, 2004); both EGF and TGF-a (ligands for EGFR) induce angiogenesis (Perrotte et al, 1999); EGFR expression and function in tumour-associated endothelial cells have also been described (Rak et al, 1995).…”

Plakophilin-2 Promotes Tumor Development by Enhancing Ligand-Dependent and -Independent Epidermal Growth Factor Receptor Dimerization and Activation

“…It was previously established that the reduction of EGFR expression or EGFR phosphorylation caused by either EGFR knockdown or EGFR inhibitors results in reduced cell proliferation and migration in MDA-MB-231 cells (23,24). Furthermore, a recent report showed that EGFR knockdown in MDA-MB-231 cells reduced tumor growth in the mammary fat pad (25).…”

Gallic acid-capped gold nanoparticles inhibit EGF-induced MMP-9 expression through suppression of p300 stabilization and NFκB/c-Jun activation in breast cancer MDA-MB-231 cells

“…In line with this finding, inhibition of EGFR activation is known to inhibit metastasis of TNBC SUM149 cells (Ueno and Zhang, 2011), while knock-down of EGFR inhibits MMP-9 expression in MDA-MB-231 cells (Nickerson et al, 2012). Mehner et al (2014) Treatment with EGF induced p300 stabilization and activation of Akt/p65 and ERK/c-Jun, leading to MMP-9 up-regulation.…”