title: Hyaluronan constitutively regulates activation of multiple receptor tyrosine kinases in epithelial and carcinoma cells.
abstract: Hyaluronan (HA) is enriched in the pericellular matrices of many malignant human tumors, and manipulations of HA interactions have strong effects on tumor progression in animal models. Increased HA production stimulates ERBB2 activation, leading to increased cell survival activities and several malignant cell properties. On the other hand, inhibition of constitutive HA-tumor cell interactions in malignant cells inhibits these properties. We have now investigated the role of HA in activation of several additional receptor tyrosine kinases (RTKs), i.e. IGF1R-beta, PDGFR-beta, EGFR and c-MET, in colon, prostate, and breast carcinoma cells. In each case we show that antagonists of endogenous HA interactions inhibit their tyrosine phosphorylation, i.e. activation. On the other hand, we show that these RTKs are activated in phenotypically normal or relatively benign tumor cells by experimentally increasing HA production. We also investigated the role of HA in constitutive versus ligand-induced activation of RTKs. In HCA7 colon and C4-2 prostate carcinoma cells, ERBB2 is constitutively activated in a ligand-independent manner, whereas IGF1R-beta and PDGFR-beta require ligand interaction for activation. We show that both constitutive activation of ERBB2 and ligand-mediated activation of IGF1R-beta and PDGFR-beta are reversed by co-treatment of the cells with a HA antagonist. We conclude that HA serves a general function in RTK activation.
authors.affiliation: Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, South Carolina 29425, USA. misra@musc.edu
authors.forename: Suniti
authors.initials: S
authors.lastname: Misra
authors.forename: Bryan P
authors.initials: BP
authors.lastname: Toole
authors.forename: Shibnath
authors.initials: S
authors.lastname: Ghatak
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D006801:Humans; D006820:Hyaluronic Acid / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D006820:Hyaluronic Acid; D020794:Receptor Protein-Tyrosine Kinases