INDUCED MITOTIC DEATH OF HELA-CELLS BY ABNORMAL EXPRESSION OF C-H-RAS

When HeLa cells were selected for stable expression of a neo gene, lin ked either to mutated or wt c-H-ras genes, morphological examination o f selected clones from several experiments revealed formation of giant multinucleated cells. These morphological alterations culminate in ce ll death, as a consequence of mitotic catastrophe (or mitotic death). Although clones expressing the mutated gene produced significantly lar ger numbers of these giant cells, those transfected with the normal al lele were also found to produce significantly more giant multinucleate d cells than non-transfected HeLa cells. Northern blot analysis of mRN A revealed overexpression of the normal H-ras gene in these clones. Ch romatin structure analysis of these clones showed gross alterations, i ncluding the presence of micronuclei and heteroploid nuclei. Interesti ngly, odd numbers of nuclei were found in colonies of these giant cell s. In addition, alterations in cell cycle parameters were observed, in cluding the appearance of a subpopulation of cells with an abnormal co ntent of DNA, probably representing dying cells. Our data support the notion that abnormal expression of H-ras contributes to mitotic catast rophe and death of a subpopulation of HeLa cells.