Mitotic and post mitotic consequences of genomic instability induced by oncogenic Ha-ras.
Induced expression of a mutant human Ha-ras oncogene in NIH3T3 cells leads to the rapid production of multicentric chromosomes, acentric chromosome fragments, double minute chromosomes, increased heteroploidy, and increased capacity to undergo gene amplification. In this study we have used fluorescent-in-situ hybridization (FISH) to demonstrate that induction of the Ha-ras oncogene also leads to disruption of the mitotic machinery, resulting in aberrant mitoses and abnormal daughter cells. Cells induced to express an oncogenic Ha-ras transgene accumulate chromosomes that lag outside of the rest of the chromosomal architecture, chromosomes that form bridges between daughter nuclei at anaphase, and that form micronuclei. Many of these mitotic aberrations contain structurally abnormal chromosomes. These ras-induced changes were suppressed by the introduction of a gene encoding the dominant negative effector of ras, raf 301. Expression of raf301 in cells induced to express Ha-ras reduced the level of growth in soft agar, chromosome aberrations, mitotic aberrations, and frequency of gene amplification. These data provide evidence for an association between Ha-ras induced transformation, chromosome aberrations and gene amplification. Furthermore they offer insight into how the cell responds to the formation of aberrant chromosomes, and how disrupting chromosomal architecture could lead to further imbalances in the distribution of genetic material between daughter cells.
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati School of Medicine, Ohio 45267, USA.
N
N
Denko
J
J
Stringer
M
M
Wani
P
P
Stambrook
D016475:3T3 Cells; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002453:Cell Cycle; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D002869:Chromosome Aberrations; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression; D011905:Genes, ras; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D051379:Mice; D008938:Mitosis; D011123:Polyploidy; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D014162:Transfection
D004791:Enzyme Inhibitors; D007544:Isopropyl Thiogalactoside; C001020:N(6),N(6)-dimethyladenine; D011505:Protein-Tyrosine Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D000225:Adenine