Differential roles for membrane-bound and soluble syndecan-1 (CD138) in breast cancer progression

Abstract

The heparan sulfate proteoglycan syndecan-1 (Sdc1) modulates cell proliferation, adhesion, migration and angiogenesis. Proteinase-mediated shedding converts Sdc1 from a membrane-bound coreceptor into a soluble effector capable of binding the same ligands. In breast carcinomas, Sdc1 overexpression correlates with poor prognosis and an aggressive phenotype. To distinguish between the roles of membrane-bound and shed forms of Sdc1 in breast cancer progression, human MCF-7 breast cancer cells were stably transfected with plasmids overexpressing wild-type (WT), constitutively shed and uncleavable forms of Sdc1. Overexpression of WT Sdc1 increased cell proliferation, whereas overexpression of constitutively shed Sdc1 decreased proliferation. Fibroblast growth factor-2-mediated mitogen-activated protein kinase signaling was reduced following small-interfering RNA (siRNA)-mediated knockdown of Sdc1 expression. Constitutively, membrane-bound Sdc1 inhibited invasiveness, whereas soluble Sdc1 promoted invasion of MCF-7 cells into matrigel matrices. The latter effect was reversed by the matrix metalloproteinase inhibitors N-isobutyl-N-(4-methoxyphenylsufonyl) glycyl hydroxamic acid and tissue inhibitor of metalloproteinase (TIMP)-1. Affymetrix microarray analysis identified TIMP-1, Furin and urokinase-type plasminogen activator receptor as genes differentially regulated in soluble Sdc1-overexpressing cells. Endogenous TIMP-1 expression was reduced in cells overexpressing soluble Sdc1 and increased in those overexpressing the constitutively membrane-bound Sdc1. Moreover, E-cadherin protein expression was downregulated in cells overexpressing soluble Sdc1. Our results suggest that the soluble and membrane-bound forms of Sdc1 play different roles at different stages of breast cancer progression. Proteolytic conversion of Sdc1 from a membrane-bound into a soluble molecule marks a switch from a proliferative to an invasive phenotype, with implications for breast cancer diagnostics and potential glycosaminoglycan-based therapies.

miR-145-dependent targeting of Junctional Adhesion Molecule A and modulation of fascin expression are associated with reduced breast cancer cell motility and invasiveness

“…22 downregulated and 8 upregulated annotated genes satisfied the filtering criteria of Po0.05 and fold change X1.5. Based on their gene ontology groupings, several genes were likely involved in the observed phenotypic changes (Table 1 and Supplementary Figure S2): JAM-A, a cell-cell adhesion molecule linked to breast cancer metastasis (Naik et al, 2008;McSherry et al, 2009), the actin bundling protein fascin, a modulator of cell motility (Vignjevic et al, 2007;Darnel et al, 2009;Kim et al, 2009b;Qualtrough et al, 2009), podocalyxinlike (PODXL), mediating cell migration (Sizemore et al, 2007;Larrucea et al, 2008), and the protease inhibitor serpin E (PAI-1) (Nikolova et al, 2009) were downregulated upon pre-miR-145 transfection, whereas actin gamma 2, transgelin and myosin-9 mRNA were upregulated. miRbase and miRGen searches identified Figure 3a).…”

The adult stem cell marker Musashi‐1 modulates endometrial carcinoma cell cycle progression and apoptosis via Notch‐1 and p21WAF1/CIP1

“…2a). qPCR analysis of factors involved in endometrial carcinoma pathogenesis (Syndecan-1, E-cadherin, PTEN) and in maintaining stem cell function (Oct-4, Sox-2, nanog, Notch-1, telomerase/TERT, see references 7,10 for discussion) revealed a significant upregulation of Notch-1 and TERT mRNA expression in Musashi-1 depleted Ishikawa cells (Fig. 2b).…”

“…10 Thirty micrograms of protein per lane were separated on 10% gels and electrotransferred to Hybond nitrocellulose membranes (GE Healthcare, Munich, Germany). Notch-1 was detected using a rabbit polyclonal antibody (H131, Santa Cruz Biotechnology) diluted 1:500 and peroxidase-labeled Goat-antiRabbit IgG (Calbiochem, Darmstadt, Germany) diluted 1:2,000.…”

Innate immune signaling induces expression and shedding of the heparan sulfate proteoglycan syndecan‐4 in cardiac fibroblasts and myocytes, affecting inflammation in the pressure‐overloaded heart

“…99 Since syndecans function as coreceptors for adhesion and growth factor receptors, their loss from the cell surface may downregulate signal transduction, affecting proliferation and migration. 100 Shedding of syndecan ectodomains occurs constitutively in some cultured cells, but is accelerated during wound healing and in response to pathological stimuli. [101][102][103][104] Indeed, syndecan ectodomains accumulate in wound fluids, consistent with a role in regulating pathophysiological events during inflammation.…”