title: The lysyl oxidase pro-peptide attenuates fibronectin-mediated activation of focal adhesion kinase and p130Cas in breast cancer cells.
abstract: The lysyl oxidase (LOX) gene encodes an enzyme (LOX) critical for extracellular matrix maturation. The LOX gene has also been shown to inhibit the transforming activity of Ras oncogene signaling. In particular, the pro-peptide domain (LOX-PP) released from the secreted precursor protein (Pro-LOX) was found to inhibit the transformed phenotype of breast, lung, and pancreatic cancer cells. However, the mechanisms of action of LOX-PP remained to be determined. Here, the ability of LOX-PP to attenuate the integrin signaling pathway, which leads to phosphorylation of focal adhesion kinase (FAK), and the activation of its downstream target p130Cas, was determined. In NF639 breast cancer cells driven by Her-2/neu, which signals via Ras, ectopic Pro-LOX and LOX-PP expression inhibited fibronectin-stimulated protein tyrosine phosphorylation. Importantly, phosphorylation of FAK on Tyr-397 and Tyr-576, and p130Cas were substantially reduced. The amount of endogenous p130Cas in the Triton X-100-insoluble protein fraction, and fibronectin-activated haptotaxis were decreased. Interestingly, expression of mature LOX enzyme enhanced fibronectin-stimulated integrin signaling. Of note, treatment with recombinant LOX-PP selectively reduced fibronectin-mediated haptotaxis of NF639, MDA-MB-231, and Hs578T breast cancer cells. Thus, evidence is provided that one mechanism of action of LOX-PP tumor suppression is to block fibronectin-stimulated signaling and cell migration.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Yingshe
authors.initials: Y
authors.lastname: Zhao
authors.forename: Chengyin
authors.initials: C
authors.lastname: Min
authors.forename: Siddharth R
authors.initials: SR
authors.lastname: Vora
authors.forename: Philip C
authors.initials: PC
authors.lastname: Trackman
authors.forename: Gail E
authors.initials: GE
authors.lastname: Sonenshein
authors.forename: Kathrin H
authors.initials: KH
authors.lastname: Kirsch
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D050719:Crk-Associated Substrate Protein / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000235:genetics; D004792:Enzyme Precursors / Q000096:biosynthesis* / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D016023:Integrins / Q000235:genetics / Q000378:metabolism; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D008249:Protein-Lysine 6-Oxidase / Q000096:biosynthesis* / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
chemical_list: D050719:Crk-Associated Substrate Protein; D004792:Enzyme Precursors; D005353:Fibronectins; D051417:Focal Adhesion Kinase 1; D016023:Integrins; D015689:Oncogene Protein p21(ras); D008249:Protein-Lysine 6-Oxidase; D018719:Erb-b2 Receptor Tyrosine Kinases; C493841:BCAR1 protein, human; C508053:ERBB2 protein, human; C496050:PTK2 protein, human