title: ROCK inhibitor reduces Myc-induced apoptosis and mediates immortalization of human keratinocytes.
abstract: The Myc/Max/Mad network plays a critical role in cell proliferation, differentiation and apoptosis and c-Myc is overexpressed in many cancers, including HPV-positive cervical cancer cell lines. Despite the tolerance of cervical cancer keratinocytes to high Myc expression, we found that the solitary transduction of the Myc gene into primary cervical and foreskin keratinocytes induced rapid cell death. These findings suggested that the anti-apoptotic activity of E7 in cervical cancer cells might be responsible for negating the apoptotic activity of over-expressed Myc. Indeed, our earlier in vitro studies demonstrated that Myc and E7 synergize in the immortalization of keratinocytes. Since we previously postulated that E7 and the ROCK inhibitor, Y-27632, were members of the same functional pathway in cell immortalization, we tested whether Y-27632 would inhibit apoptosis induced by the over-expression of Myc. Our findings indicate that Y-27632 rapidly inhibited Myc-induced membrane blebbing and cellular apoptosis and, more generally, functioned as an inhibitor of extrinsic and intrinsic pathways of cell death. Most important, Y-27632 cooperated with Myc to immortalize keratinocytes efficiently, indicating that apoptosis is a major barrier to Myc-induced immortalization of keratinocytes. The anti-apoptotic activity of Y-27632 correlated with a reduction in p53 serine 15 phosphorylation and the consequent reduction in the expression of downstream target genes p21 and DAPK1, two genes involved in the induction of cell death.
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Dakic
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: DiVito
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Shuang
authors.initials: S
authors.lastname: Fang
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Suprynowicz
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Anirudh
authors.initials: A
authors.lastname: Gaur
authors.affiliation: Department of Biostatistics, Bioinformatics, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Palechor-Ceron
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Vera
authors.initials: V
authors.lastname: Simic
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Choudhury
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Songtao
authors.initials: S
authors.lastname: Yu
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Simbulan-Rosenthal
authors.affiliation: Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Dean
authors.initials: D
authors.lastname: Rosenthal
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Schlegel
authors.affiliation: Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.|Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Liu
mesh_terms: D000577:Amides / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D002472:Cell Transformation, Viral / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D064550:Death-Associated Protein Kinases / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000821:virology; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000577:Amides; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D011725:Pyridines; D016159:Tumor Suppressor Protein p53; C108830:Y 27632; C579096:DAPK1 protein, human; D064550:Death-Associated Protein Kinases; D054460:rho-Associated Kinases
keywords: Myc; ROCK; apoptosis; cytoskeleton; telomerase