Loss of HSulf-1 Expression Enhances Autocrine Signaling Mediated by Amphiregulin in Breast Cancer

Abstract

Heparan sulfate (HS) glycosaminoglycans are the oligosaccharide chains of heparan sulfate proteoglycans. The sulfation of HS glycosaminoglycan residues is required for its interaction with various heparin-binding growth factors to promote their biological activities to activate their high affinity receptor tyrosine kinases. We have identified HS glycosaminoglycan-6-O-endosulfatase HSulf-1 as a down-regulated gene in ovarian, breast, and several other cancer cell lines. Here we have shown that HSulf-1 inhibits autocrine activation of the EGFR-ERK (epidermal growth factor receptor-extracellular signal-regulated kinase) pathway induced by serum withdrawal in MDA-MB-468 breast cancer cells. Short hairpin RNA-mediated down-regulation of HSulf-1 in HSulf-1 clonal lines of MDA-MB-468 led to a significant increase in autocrine activation of ERK compared with vector only control. The autocrine signaling was also inhibited with neutralization antibodies against amphiregulin and HB-EGF, the heparin-binding growth factor family of the EGF superfamily. Furthermore, HSulf-1-mediated inhibition of autocrine signaling was associated with reduced cyclin D1 levels, leading to decreased S phase fraction and increased G 2 -M fraction, as well as increased cell death. Finally, evaluation of HSulf-1 expression levels in primary invasive breast tumors by RNA in situ hybridization indicated that HSulf-1 is down-regulated in the majority (60%) of tumors, with a predominant association with lobular histology. These data suggest a potential role of HSulf-1 down-regulation in mammary carcinogenesis.Breast cancer is the most common type of cancer among women in the United States. Despite the advances in early detection and therapeutic treatment options, an estimated 215,000 new cases and 41,000 deaths were reported in 2006 (1). One of the molecular signatures known to be associated with poor prognosis is the epidermal growth factor receptor (EGFR).2 The EGFR expression in breast cancer is often associated with resistance to endocrine hormone therapy (2, 3). Recent studies also indicate that hormone-induced estrogen receptor (ER) activation leads to activation of EGFR, suggesting that cross-talk between the two signaling pathways may be a crucial drug-resistant mechanism in ER-positive breast tumors (4). In addition, gene expression profiling studies identified the basal-like tumor as one of the breast tumor subtypes characterized with EGFR expression and poor prognosis (5, 6). EGFR signaling is induced by various EGF-like growth factor family ligands, such as EGF, amphiregulin, heparin-binding EGF-like growth factor (HB-EGF), betacellulin, epiregulin, and transforming growth factor-␣ (7). Amphiregulin is one of the most investigated EGFR ligands in relation to breast cancer. Amphiregulin is a heparin-binding growth factor that requires heparan sulfate (HS) glycosaminoglycans as a low affinity coreceptor (8) and is overexpressed in the majority of primary breast tumors (9). Expression of amphiregulin and EGFR are seen both in breast tumors a...

Cloning and Characterization of a Novel Chondroitin Sulfate/Dermatan Sulfate 4-O-Endosulfatase from a Marine Bacterium

“…Together with the sulfatase reported here, however, only three GAG endosulfatases have yet been identified from animals (40) and bacteria (24). The roles of HS 6-O-endosulfatase in animals have been widely and actively studied in biological processes from embryo development to tumorigenesis (41)(42)(43). However, this enzyme has rarely been used as a tool for structurefunction studies of HS in vitro, which might be due to its low activity and instability.…”

Quail Sulf1 Function Requires Asparagine-linked Glycosylation

“…A number of previous studies have characterized dynamic mRNA expression of Sulf1 and Sulf2 in embryonic and adult tissues (4,8,9). Sulfs also undergo post-translational modification, including cleavage by furin-like proteases and N-glycosylation (10).…”

Comparison of the effects of differentially sulphated bovine kidney- and porcine intestine-derived heparan sulphate on breast carcinoma cellular behaviour

“…Degradation of heparan sulphate by heparinase treatment abolished binding of the growth factor as well as the FGF-2-induced tumour growth (30). Down-regulation of SULF-1 in MDA-MB-468 breast cancer cells, with the resultant persistent presence of 6-O-sulphate groups on heparan sulphate molecules, increases autocrine activation of the epidermal growth factor receptor-extracellular signalregulated kinase (EGFR-ERK) pathway, mediated via amphiregulin and heparin-binding EGF-like growth factor (HB-EGF) (50). In addition, loss of SULF-1 has been shown to increase cell proliferation in tumour-associated angiogenesis through FGF-2, hepatocyte growth factor, and vascular endothelial growth factor (VEGF) signalling.…”