title: Targeting Fyn in Ras-transformed cells induces F-actin to promote adherens junction-mediated cell-cell adhesion.
abstract: Fyn, a member of the Src family kinases (SFK), is an oncogene in murine epidermis and is associated with cell-cell adhesion turnover and induction of cell migration. Additionally, Fyn upregulation has been reported in multiple tumor types, including cutaneous squamous cell carcinoma (cSCC). Introduction of active H-Ras(G12V) into the HaCaT human keratinocyte cell line resulted in upregulation of Fyn mRNA (200-fold) and protein, while expression of other SFKs remained unaltered. Transduction of active Ras or Fyn was sufficient to induce an epithelial-to-mesenchymal transition in HaCaT cells. Inhibition of Fyn activity, using siRNA or the clinical SFK inhibitor Dasatinib, increased cell-cell adhesion and rapidly (5-60 min) increased levels of cortical F-actin. Fyn inhibition with siRNA or Dasatinib also induced F-actin in MDA-MB-231 breast cancer cells, which have elevated Fyn. F-actin co-localized with adherens junction proteins, and Dasatinib-induced cell-cell adhesion could be blocked by Cytochalasin D, indicating that F-actin polymerization was a key initiator of cell-cell adhesion through the adherens junction. Conversely, inhibiting cell-cell adhesion with low Ca(2+) media did not block Dasatinib-induced F-actin polymerization. Inhibition of the Rho effector kinase ROCK blocked Dasatinib-induced F-actin and cell-cell adhesion, implicating relief of Rho GTPase inhibition as a mechanism of Dasatinib-induced cell-cell adhesion. Finally, topical Dasatinib treatment significantly reduced total tumor burden in the SKH1 mouse model of UV-induced skin carcinogenesis. Together these results identify the promotion of actin-based cell-cell adhesion as a newly described mechanism of action for Dasatinib and suggest that Fyn inhibition may be an effective therapeutic approach in treating cSCC.
authors: Molecular Biology Program, Loyola University Chicago, Maywood, Illinois.|Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, Illinois.
authors: Sarah E
authors: SE
authors: Fenton
authors: Department of Pathology, Loyola University Chicago, Maywood, Illinois.
authors: Kelli A
authors: KA
authors: Hutchens
authors: Molecular Biology Program, Loyola University Chicago, Maywood, Illinois.|Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, Illinois.|Department of Pathology, Loyola University Chicago, Maywood, Illinois.
authors: Mitchell F
authors: MF
authors: Denning
mesh_terms: D000199:Actins / Q000235:genetics*; D022005:Adherens Junctions / Q000187:drug effects / Q000235:genetics*; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics*; D045744:Cell Line, Tumor; D000069439:Dasatinib / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics; D005260:Female; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects; D051379:Mice; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D018631:ras Proteins / Q000235:genetics*; D054460:rho-Associated Kinases / Q000235:genetics
chemical_list: D000199:Actins; D012333:RNA, Messenger; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D054460:rho-Associated Kinases; D018631:ras Proteins; D000069439:Dasatinib
keywords: Dasatinib; Twist; UV radiation; cutaneous squamous cell carcinoma; keratinocytes; skin carcinogenesis