title: The RAS oncogene induces genomic instability in thyroid PCCL3 cells via the MAPK pathway.
abstract: Activating mutations of RAS are thought to be early events in the evolution of thyroid follicular neoplasms. We used a doxycycline-inducible expression system to explore the acute effects of H-RAS12 on genomic stability in thyroid PCCL3 cells. At 2-3 days (first or second cell cycle) there was a significant increase in the frequency of micronucleation. Treatment of cells with YVAD-CHO inhibited RAS-induced apoptosis, but had no effect on micronucleation. The effects of H-RAS(V12) were mediated by activation of MAPK, as treatment with PD98059 at concentrations verified to selectively inhibit MEK1 reduced the frequency of prevalence of cells with micronuclei. In addition, doxycycline-inducible expression of a constitutively active MEK1, but not of a mutant RAC1, mimicked the effects of H-RAS(V12). The effects of H-RAS(V12) on genome destabilization were apparent even though the sequence of p53 in PCCL3 cells was confirmed to be wild-type. Acute activation of H-RAS(V12) evoked a proportional increase in both CREST negative and CREST positive micronuclei, indicating that both clastogenic and aneugenic effects were involved. H-RAS(V12) and activated MEK1 also induced centrosome amplification, and chromosome misalignment. Evidence that acute expression of constitutively activated RAS destabilizes the genome of PCCL3 cells is consistent with a mode of tumor initiation in which this oncogene promotes phenotypic progression by predisposing to large scale genomic abnormalities.
authors.affiliation: Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Ohio 45267, USA.
authors.forename: H I
authors.initials: HI
authors.lastname: Saavedra
authors.forename: J A
authors.initials: JA
authors.lastname: Knauf
authors.forename: J M
authors.initials: JM
authors.lastname: Shirokawa
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: B
authors.initials: B
authors.lastname: Ouyang
authors.forename: R
authors.initials: R
authors.lastname: Elisei
authors.forename: P J
authors.initials: PJ
authors.lastname: Stambrook
authors.forename: J A
authors.initials: JA
authors.lastname: Fagin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000235:genetics; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D051381:Rats; D029701:Saccharomyces cerevisiae Proteins; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020830:rac1 GTP-Binding Protein / Q000235:genetics; D018631:ras Proteins / Q000235:genetics*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004791:Enzyme Inhibitors; D005419:Flavonoids; D029701:Saccharomyces cerevisiae Proteins; C068688:centromere protein E; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; C087358:PTC1 protein, S cerevisiae; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D000071636:Protein Phosphatase 2C; D020830:rac1 GTP-Binding Protein; D018631:ras Proteins; D004318:Doxycycline; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one