title: Membrane type 1 matrix metalloproteinase-mediated stromal syndecan-1 shedding stimulates breast carcinoma cell proliferation.
abstract: Mounting evidence implicates stromal fibroblasts in breast carcinoma progression. We have recently shown in three-dimensional coculture experiments that human mammary fibroblasts stimulate the proliferation of T47D breast carcinoma cells and that this activity requires the shedding of the heparan sulfate proteoglycan syndecan-1 (Sdc1) from the fibroblast surface. The goal of this project was to determine the mechanism of Sdc1 ectodomain shedding. The broad spectrum matrix metalloproteinase (MMP) inhibitor GM6001 specifically blocked Sdc1-mediated carcinoma cell growth stimulation, pointing toward MMPs as critical enzymes involved in Sdc1 shedding. MMP-2 and membrane type 1 MMP (MT1-MMP) were the predominant MMPs expressed by the mammary fibroblasts. Fibroblast-dependent carcinoma cell growth stimulation in three-dimensional coculture was abolished by MT1-MMP expression silencing with small interfering RNA and restored either by adding recombinant MT1-MMP catalytic domain or by expressing a secreted form of Sdc1 in the fibroblasts. These findings are consistent with a model where fibroblast-derived MT1-MMP cleaves Sdc1 at the fibroblast surface, leading to paracrine growth stimulation of carcinoma cells by Sdc1 ectodomain. The relevance of MT1-MMP in paracrine interactions was further supported by coculture experiments with T47D cells and primary fibroblasts isolated from human breast carcinomas or matched normal breast tissue. Carcinoma-associated fibroblasts stimulated T47D cell proliferation significantly more than normal fibroblasts in three-dimensional coculture. Function-blocking anti-MT1-MMP antibody significantly inhibited the T47D cell growth stimulation in coculture with primary fibroblasts. In summary, these results ascribe a novel role to fibroblast-derived MT1-MMP in stromal-epithelial signaling in breast carcinomas.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, WI 53792-8550, USA.
authors.forename: Gui
authors.initials: G
authors.lastname: Su
authors.forename: Stacy A
authors.initials: SA
authors.lastname: Blaine
authors.forename: Dianhua
authors.initials: D
authors.lastname: Qiao
authors.forename: Andreas
authors.initials: A
authors.lastname: Friedl
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D005347:Fibroblasts / Q000502:physiology; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000502:physiology; D061965:Matrix Metalloproteinase Inhibitors; D034741:RNA, Small Interfering / Q000494:pharmacology; D053668:Syndecan-1 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D034741:RNA, Small Interfering; C508241:SDC1 protein, human; D053668:Syndecan-1; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14