title: CD44 regulates cell migration in human colon cancer cells via Lyn kinase and AKT phosphorylation.
abstract: Colon cancer is among the leading causes of cancer death in North America. CD44, an adhesion and antiapoptotic molecule is overexpressed in colon cancer. Cofilin is involved in the directional motility of cells. In the present study, we looked at how CD44 might modulate cell migration in human colon cancer via cofilin. We used a human colon cancer cell line, HT29, which expresses CD44, HT29 where CD44 expression was knocked down by siRNA, SW620, a human colon cancer cell line which does not express CD44, stably transfected exons of CD44 in SW620 cells and the colon from CD44 knockout and wild-type mouse. Western blot analysis of siRNA CD44 lysates showed increased level of AKT phosphorylation and decreased level of cofilin expression. Similar results were also observed with SW620 cells and CD44 knockout mouse colon lysates. Experiments using the AKT phosphorylation inhibitor LY294002 indicate that AKT phosphorylation downregulates cofilin. Immunoprecipitation studies showed CD44 complex formation with Lyn, providing an essential link between CD44 and AKT phosphorylation. LY294002 also stabilized Lyn from phosphorylated AKT, suggesting an interaction between Lyn and AKT phosphorylation. Immunocytochemistry showed that cofilin and Lyn expression were downregulated in siRNA CD44 cells and CD44 knockout mouse colon. siRNA CD44 cells had significantly less migration compared to HT29 vector. Given the well-defined roles of CD44, phosphorylated AKT in apoptosis and cancer, these results indicate that CD44-induced cell migration is dependent on its complex formation with Lyn and its consequent regulation of AKT phosphorylation and cofilin expression.
authors.affiliation: Department of Laboratory Medicine, St. Michael's Hospital, 30 Bond Street, Toronto, ON, Canada.
authors.forename: Venkateswaran
authors.initials: V
authors.lastname: Subramaniam
authors.forename: Isabella R
authors.initials: IR
authors.lastname: Vincent
authors.forename: Helena
authors.initials: H
authors.lastname: Gardner
authors.forename: Emily
authors.initials: E
authors.lastname: Chan
authors.forename: Helena
authors.initials: H
authors.lastname: Dhamko
authors.forename: Serge
authors.initials: S
authors.lastname: Jothy
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement; D003106:Colon / Q000166:cytology; D003110:Colonic Neoplasms / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D020868:Gene Silencing; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics*; D051379:Mice; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D018960:Hyaluronan Receptors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt