title: Soluble CD44 secretion contributes to the acquisition of aggressive tumor phenotype in human colon cancer cells.
abstract: CD44, a widely distributed cell surface glycoprotein and a receptor for hyaluronan (HA), has been implicated in facilitating tumor growth and metastasis, antiapoptosis and directional motility of cancer cells. In order to investigate the role of soluble CD44 (CD44(sol)) in colon cancer cell growth, SW620, a human colon cancer cell line deficient in CD44 expression was stably transfected with human CD44 cDNA containing exons 1-5, 15 and 16 of the human CD44. Western blot analyses demonstrated the presence of 78 kDa soluble CD44 protein in the culture supernatant of stably transfected cell lines (CD44(sol) clones) and were not detected in the empty vector control line (clone m). The CD44(sol) transfected cells showed higher cell proliferation and clonal growth in vitro, confirmed by MTT and clonogenic assays respectively, when compared to the control cells. Cell adhesion to hyaluronan was significantly lower with CD44(sol) cells compared to the control cells. Western blot analyses were negative for cleaved PARP in lysates from CD44(sol) cells, suggesting resistance to apoptosis. These findings indicate that the secretion of soluble CD44 contributes to colon cancer growth in vitro, possibly as a decoy receptor.
authors.affiliation: Department of Laboratory Medicine and Li Ka Shing Knowledge Institute, St Michael's Hospital Toronto, Ontario, Canada.
authors.forename: Venkateswaran
authors.initials: V
authors.lastname: Subramaniam
authors.forename: Helena
authors.initials: H
authors.lastname: Gardner
authors.forename: Serge
authors.initials: S
authors.lastname: Jothy
mesh_terms: D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism; D051379:Mice; D010641:Phenotype
chemical_list: C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid