| pubmed-article:16711390 | pubmed:abstractText | Introduction of bcl-2 gene in EIA + c-Ha-ras-transformed rat embryo fibroblasts, which are unable to be arrested after damaging influences and possess high proapoptotic sensitivity, results not only in suppression of cell death but also in re-establishment of cell cycle block following DNA damage and serum starvation. Flow cytometry showed that E1A + c-Ha-ras + bcl-2-transformants treated with DNA-intercalator adriamycin are capable of being arrested at G1/S boundary for a long time (for less than 5 days). According to the growth curve data, the number of Bcl-2-overexpressing cells remanins constant for a week of cultivation with adriamycin. Clonogenic efficacy of E1A + c-Ha-ras + bcl-2-cells is brought to no already in 16 h after adriamycin addition. Apoptotic death, revealed by oligonucleosomic fragmentation of DNA, as well as cell death, occurring due to mitotic catastrophe, after adriamycin treatment are almost absent in Bcl-2-overexpressing transformants, as compared with parental E1A + c-Ha-ras-transformants. Bcl-2 introduction in E1A + c-Ha-ras-transformants is accompanied by a rise of SA beta-Gal (Senescence Associated beta-Galactosidase) activity, which is commonly considered to be a marker of cell senescence. Adriamycin treatment of E1A + c-Ha-ras + bcl-2-transformants results in a much higher rise in SA beta-Gal activity, as compared with untreated cells. Co-immunoprecipitation experiments demonstrated the introduction of Bcl-2 to result in formation of Bcl-2 complexes with early region E1A oncoproducts, which are thought to be responsible for proapoptotic susceptibility of E1A-expressing transformants. The data obtained lead to suggestion that bcl-2 transfer to E1A + c-Ha-ras-transformants may induce a switch from the cell death program on the program of senescence after DNA damage, due, presumably, to Bcl-2 interaction with the apoptosis activator the viral oncoprotein E1A. | lld:pubmed |
