title: Src and caveolin-1 reciprocally regulate metastasis via a common downstream signaling pathway in bladder cancer.
abstract: In bladder cancer, increased caveolin-1 (Cav-1) expression and decreased Src expression and kinase activity correlate with tumor aggressiveness. Here, we investigate the clinical and functional significance, if any, of this reciprocal expression in bladder cancer metastasis. We evaluated the ability of tumor Cav-1 and Src RNA and protein expression to predict outcome following cystectomy in 257 patients enrolled in two independent clinical studies. In both, high Cav-1 and low Src levels were associated with metastasis development. We overexpressed or depleted Cav-1 and Src protein levels in UMUC-3 and RT4 human bladder cancer cells and evaluated the effect of this on actin stress fibers, migration using Transwells, and lung metastasis following tail vein inoculation. Cav-1 depletion or expression of active Src in metastatic UMUC-3 cells decreases actin stress fibers, cell migration, and metastasis, while Cav-1 overexpression or Src depletion increased the migration of nonmetastatic RT4 cells. Biochemical studies indicated that Cav-1 mediates these effects via its phosphorylated form (pY14), whereas Src effects are mediated through phosphorylation of p190RhoGAP and these pathways converge to reduce activity of RhoA, RhoC, and Rho effector ROCK1. Treatment with a ROCK inhibitor reduced UMUC-3 lung metastasis in vivo, phenocopying the effect of Cav-1 depletion or expression of active Src. Src suppresses whereas Cav-1 promotes metastasis of bladder cancer through a pharmacologically tractable common downstream signaling pathway. Clinical evaluation of personalized therapy to suppress metastasis development based on Cav-1 and Src profiles seems warranted.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Shibu
authors.initials: S
authors.lastname: Thomas
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Overdevest
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Nitz
authors.forename: Paul D
authors.initials: PD
authors.lastname: Williams
authors.forename: Charles R
authors.initials: CR
authors.lastname: Owens
authors.forename: Marta
authors.initials: M
authors.lastname: Sanchez-Carbayo
authors.forename: Henry F
authors.initials: HF
authors.lastname: Frierson
authors.forename: Martin A
authors.initials: MA
authors.lastname: Schwartz
authors.forename: Dan
authors.initials: D
authors.lastname: Theodorescu
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D004195:Disease Models, Animal; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000556:secondary*; D051379:Mice; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology*; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D054460:rho-Associated Kinases / Q000096:biosynthesis; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D000199:Actins; D014408:Biomarkers, Tumor; D051242:Caveolin 1; D019061:src-Family Kinases; C515851:ROCK1 protein, human; C515854:Rock1 protein, mouse; D054460:rho-Associated Kinases; D020741:rho GTP-Binding Proteins