title: Interaction of human breast fibroblasts with collagen I increases secretion of procathepsin B.
abstract: Interactions of stromal and tumor cells with the extracellular matrix may regulate expression of proteases including the lysosomal proteases cathepsins B and D. In the present study, we determined whether the expression of these two proteases in human breast fibroblasts was modulated by interactions with the extracellular matrix component, collagen I. Breast fibroblasts were isolated from non-malignant breast tissue as well as from tissue surrounding malignant human breast tumors. Growth of these fibroblasts on collagen I gels affected cell morphology, but not the intracellular localization of vesicles staining for cathepsin B or D. Cathepsins B and D levels (mRNA or intracellular protein) were not affected in fibroblasts growing on collagen I gels or plastic, nor was cathepsin D secreted from these cells. In contrast, protein expression and secretion of cathepsin B, primarily procathepsin B, was induced by growth on collagen I gels. The induced secretion appeared to be mediated by integrins binding to collagen I, as inhibitory antibodies against alpha(1), alpha(2), and beta(1) integrin subunits prevented procathepsin B secretion from fibroblasts grown on collagen. In addition, procathepsin B secretion was induced when cells were plated on beta(1) integrin antibodies. To our knowledge, this is the first examination of cathepsin B and D expression and localization in human breast fibroblasts and their regulation by a matrix protein. Secretion of the cysteine protease procathepsin B from breast fibroblasts may have physiological and pathological consequences, as proteases are required for normal development and for lactation of the mammary gland, yet can also initiate and accelerate the progression of breast cancer.
authors.affiliation: Barbara Ann Karmanos Cancer Institute, Wayne State University, School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Koblinski
authors.forename: Julie
authors.initials: J
authors.lastname: Dosescu
authors.forename: Mansoureh
authors.initials: M
authors.lastname: Sameni
authors.forename: Kamiar
authors.initials: K
authors.lastname: Moin
authors.forename: Katherine
authors.initials: K
authors.lastname: Clark
authors.forename: Bonnie F
authors.initials: BF
authors.lastname: Sloane
mesh_terms: D001940:Breast / Q000166:cytology*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D002401:Cathepsin B / Q000235:genetics* / Q000378:metabolism*; D002455:Cell Division; D002478:Cells, Cultured; D024042:Collagen Type I / Q000502:physiology*; D017077:Culture Media, Conditioned; D004792:Enzyme Precursors / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D016023:Integrins / Q000096:biosynthesis; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: D024042:Collagen Type I; D017077:Culture Media, Conditioned; D004792:Enzyme Precursors; D016023:Integrins; C057832:procathepsin B; D002401:Cathepsin B