Protein expression profiling identifies cyclophilin A as a molecular target in Fhit-mediated tumor suppression.
Loss of fragile histidine triad (Fhit) expression is often associated with human malignancies, and Fhit functions as a tumor suppressor in controlling cell growth and apoptosis, although specific signal pathways are still undefined. We have used a proteomic approach to define proteins in the Fhit-mediated tumor suppression pathway. Because substitution of Tyr(114) (Y114) with phenylalanine (Y114F) diminishes Fhit functions, we did protein expression profiling to identify proteins differentially expressed in Fhit-negative H1299 lung cancer cells infected with wild-type (Ad-FHIT-wt) and Y114 mutant FHIT-expressing (Ad-FHIT-Y114F) adenoviruses. Among 12 distinct proteins that exhibited 4-fold differences in expression on comparison of the two infected cell lysates, cyclophilin A, the intracellular reporter of the immunosuppressive drug cyclosporine A, showed a remarkably decreased protein level in cells infected with Ad-FHIT-wt versus Ad-FHIT-Y114F. Conversely, loss of Fhit expression resulted in increased cyclophilin A expression in mouse tissues and cell lines. Restoration of Fhit expression led to down-regulated cyclophilin A protein expression and subsequently prevented cyclophilin A-induced up-regulation of cyclin D1, Cdk4, and resultant cell cycle progression (G(1)-S transition), which was independent of Ca(2+)/calmodulin-dependent kinase inhibitor, KN-93. Interestingly, Fhit down-modulation of phosphatase activity of calcineurin, which controls cyclin D1/Cdk4 activation, was reversed by cyclophilin A treatment in a concentration-dependent manner, a reversal that was inhibited by additional cyclosporine A treatment. Thus, cyclophilin A is a downstream target in Fhit-mediated cessation of cell cycle progression at late G(1) phase. Elucidation of the protein effectors of Fhit signaling may lead to identification of targets for lung cancer therapy.
Semba
Shuho
S
Comprehensive Cancer Center and Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Room 455C, Wiseman Hall, 410 West 12th Avenue, Columbus, 43210, USA.
Huebner
Kay
K
D017766:Acid Anhydride Hydrolases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D019703:Calcineurin / Q000378:metabolism; D002453:Cell Cycle; D021984:Cyclophilin A / Q000502:physiology*; D016193:G1 Phase / Q000235:genetics; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D017354:Point Mutation; D040081:Protein Array Analysis / Q000379:methods*; D016196:S Phase / Q000235:genetics; D014161:Transduction, Genetic; D019076:Transgenes; D014407:Tumor Cells, Cultured; D000099170:Bis(5'-adenosyl)triphosphatase
D017766:Acid Anhydride Hydrolases; D019703:Calcineurin; D021984:Cyclophilin A; D009363:Neoplasm Proteins; D000099170:Bis(5'-adenosyl)triphosphatase