title: The transcription factor NFAT1 induces apoptosis through cooperation with Ras/Raf/MEK/ERK pathway and upregulation of TNF-α expression.
abstract: Nuclear factor of activated T cells (NFAT) was described as an activation and differentiation factor in T cells. NFAT1 protein is expressed in several cell types and has been implicated in the control of the cell cycle, death and migration. Overexpression or activation of NFAT1 has been demonstrated to induce cell death in different cell types, such as T lymphocytes, Burkitt's lymphoma, and fibroblasts. Although these findings indicate a role for NFAT1 transcription factor in control of cell death, the precise mechanisms involved in this process regulated by NFAT1 are still poorly understood. The Ras/Raf/MEK/ERK pathway is activated by many growth factors and cytokines that are important in driving proliferation and preventing apoptosis and is widely implicated in cell transformation and cancer development. We show that NFAT1 protein can cooperate with Ras/Raf/MEK/ERK, but not with the JNK, p38 or NFκB pathways in cell death induction. NFAT1 can induce a cell death pathway consistent with apoptosis, which can be shifted to programmed necrosis by caspase inhibitors. Finally, through screening genes involved in cell death regulation, although we determined that TNF-α, TRAIL and PAK7 genes were up-regulated, only TNF-α expression was responsible for cell death in this context. These data suggest that NFAT1 protein activation can shift oncogenic Ras/Raf/MEK/ERK signaling to acting as a tumor suppressor pathway. These data support a potential role for regulating NFAT1 expression in gene therapy in tumors that display an activated Ras pathway, which could lead to more specific, target-directed TNF-α expression and, thus, tumor suppression.
authors.affiliation: Brazilian National Cancer Institute, Rio de Janeiro, Brazil.
authors.forename: Bruno K
authors.initials: BK
authors.lastname: Robbs
authors.forename: Pedro I
authors.initials: PI
authors.lastname: Lucena
authors.forename: João P B
authors.initials: JP
authors.lastname: Viola
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000235:genetics; D002460:Cell Line; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000502:physiology*; D051379:Mice; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism*; D041681:NIH 3T3 Cells; D009336:Necrosis / Q000235:genetics / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation; D054462:p21-Activated Kinases / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D050778:NFATC Transcription Factors; C494007:Nfatc2 protein, mouse; D053221:TNF-Related Apoptosis-Inducing Ligand; C505654:Tnfsf10 protein, mouse; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C486708:Pak7 protein, mouse; D019908:Proto-Oncogene Proteins c-raf; D054462:p21-Activated Kinases; D020169:Caspases; D018631:ras Proteins