title: Disruption of MKK4 signaling reveals its tumor-suppressor role in embryonic stem cells.
abstract: The dual Ser/Thr kinase MKK4 and its downstream targets JNK and p38 regulate critical cellular functions during embryogenesis and development. MKK4 has been identified as a putative tumor-suppressor gene in human solid tumors of breast, prostate and pancreas. To clarify the mechanisms underlying the transforming potential of molecular defects targeting MKK4, we have generated totipotent embryonic stem (ES) cells expressing the dominant-negative mutant DN-MKK4(Ala), S257A/T261A. Stably transfected DN-MKK4-ES cells exhibit a transformed fibroblast-like morphology, reduced proliferation rate, were no more submitted to cell contact inhibition, were growing in soft agar, and were much more tumorigenic than parental ES cells in athymic nude mice. These phenotypic changes: (i) are consistent with the protection of DN-MKK4-transfected ES cells from spontaneous, cell density-dependent, and stress-induced apoptosis (DAPI staining and poly (ADP-ribose) polymerase (PARP) cleavage) and (ii) correlated with alterations in JNK, p38, and Erk-1/-2 MAPK/SAPK signaling. Taken together, our data provide a new mechanism linking the MKK4 signaling pathways to cancer progression and identify MKK4 as a tumor-suppressor gene implicated in several transforming functions.
authors.affiliation: 1INSERM U.481, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, BP 416, 75870-Paris 18, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Cazillis
authors.forename: Annie-France
authors.initials: AF
authors.lastname: Bringuier
authors.forename: Danièle
authors.initials: D
authors.lastname: Delautier
authors.forename: Maud
authors.initials: M
authors.lastname: Buisine
authors.forename: Dominique
authors.initials: D
authors.lastname: Bernuau
authors.forename: Christian
authors.initials: C
authors.lastname: Gespach
authors.forename: André
authors.initials: A
authors.lastname: Groyer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology; D016147:Genes, Tumor Suppressor; D020935:MAP Kinase Signaling System / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation; D009368:Neoplasm Transplantation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology / Q000201:enzymology*; D013997:Time Factors; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D011506:Proteins; D016755:Proto-Oncogene Proteins c-jun; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases