[Changes in the activity of cyclin-kinase complexes governing cell transition from G1 phase to DNA replication phase in E1A + c-Ha-ras transformants transfected with the bcl-2 gene].
The antiproliferative effect of human bcl-2 gene transferred to E1A + c-Ha-ras-transformed rat embryo fibroblasts, which are characterized by the absence of cell cycle checkpoints after damage and by a high proapoptotic sensitivity was studied. Ionizing irradiation, adriamycin treatment, and serum starvation were shown to induce G1/S arrest in E1A + c-Ha-ras-transformants. Bcl-2 antiproliferative effect in E1A + c-Ha-ras-transformants was not associated with alterations in Cdk2, cyclin E and A contents. G1/S arrest following irradiation or serum starvation was accompanied by a decrease in kinase activity associated with cyclin E-cdk2, whereas G1/S arrest in tetraploid subpopulation after adriamycin treatment did not correlate with a decrease in cyclin E-associated kinase activity. Cyclin A-associated kinase activity did not decrease after any used treatment. Transfection of bcl-2 in E1A + c-Ha-ras-transformants resulted in elevated expression of cyclin-cdk complexes inhibitor p21/Waf-1, but not p27/Kip. Damaging agents caused p21/Waf-1 and p27/Kip accumulation, but bcl-2 overexpression did not restore functions of these inhibitors, since p21/Waf-1 and p27/Kip were unable to suppress cyclin-cdk complexes activity after damage. These results suggest that bcl-2 transfection in E1A + c-Ha-ras-transformants is likely to result in irradiation- or serum starvation-induced G1/S arrest accomplished by a selective decrease in cyclin E-associated kinase activity. Adriamycin-induced G1/S arrest seems to be realized via cyclin-cdk complexes activity-independent way involving antiproliferative targets downstream of cyclin E-cdk2 and cyclin A-cdk2 complexes.
Institute of Cytology RAS, St. Petersburg.
A M
AM
Neliudova
N D
ND
Aksenov
T V
TV
Pospelova
D017500:Adenovirus E1A Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle / Q000235:genetics* / Q000528:radiation effects*; D002460:Cell Line; D002461:Cell Line, Transformed; D016895:Culture Media, Serum-Free; D019925:Cyclin A / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism / Q000528:radiation effects; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000528:radiation effects; D016213:Cyclins / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D004622:Embryo, Mammalian / Q000166:cytology; D004791:Enzyme Inhibitors / Q000378:metabolism; D005347:Fibroblasts; D016193:G1 Phase; D019254:Genes, bcl-2 / Q000235:genetics; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D011839:Radiation, Ionizing; D051381:Rats; D016196:S Phase; D014162:Transfection
D017500:Adenovirus E1A Proteins; D016895:Culture Media, Serum-Free; D019925:Cyclin A; D019927:Cyclin E; D016213:Cyclins; D004791:Enzyme Inhibitors; D004317:Doxorubicin; D018844:Cyclin-Dependent Kinases