title: TC21 mediates transformation and cell survival via activation of phosphatidylinositol 3-kinase/Akt and NF-kappaB signaling pathway.
abstract: The signaling pathways of TC21-mediated transformation and cell survival are not well-established. In this study, we have investigated the role of PI3-K/Akt signaling pathway in oncogenic-TC21-mediated transformation and cell survival. We found that oncogenic-TC21 stimulated the PI3-K activity. This was associated with the activation of Akt, a key component of PI3-K signaling pathway. We also found that TC21 interacted and formed complex with PI3-K. Mutations in the GTP-binding region of TC21, which enhanced GTP-binding potential of this protein, also stimulated its association with PI3-K, suggesting that PI3-K may preferentially interact with the GTP-bound form. Suppression of PI3-K and Akt by specific inhibitors LY294002 and Wortmannin reversed TC21-induced transformation. Likewise, inhibition of PI3-K activity by the PI3-K phosphotase PTEN reduced TC21-mediated focus formation in NIH3T3 cells. Investigation of TC21's effect on cell survival revealed that mutant-TC21 expressing cells were more resistant to etoposide- and cisplatin-induced cell death, and this was associated with the activation of anti-apoptotic protein NF-kappaB, a downstream target of Akt. Treatment of PI3-K inhibitor LY294002 significantly suppressed TC21-mediated NF-kappaB activation. In conclusion, we have identified PI3-K as an effector of TC21 and demonstrated that the PI3-K/Akt signaling pathway plays important roles in TC21-mediated transformation and cell survival.
authors.affiliation: Department of Pharmacology, State University of New York, Upstate Medical University, 750 E. Adams Street, Syracuse, NY 13210, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Rong
authors.forename: Qin
authors.initials: Q
authors.lastname: He
authors.forename: Yusen
authors.initials: Y
authors.lastname: Liu
authors.forename: M Saeed
authors.initials: MS
authors.lastname: Sheikh
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic; D004789:Enzyme Activation; D017930:Genes, Reporter; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases; D020559:Monomeric GTP-Binding Proteins; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C494918:AKT1 protein, human; C087360:RRAS2 protein, human; C490200:Rras2 protein, mouse