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PubMed · 11840777

[Rat embryo fibroblasts transformed by complementation with oncogenes E1A+E1B-19 and E1A+cHa-ras differ in the ability to realize the G1/S block in serum free media].

A I Brichkina·N D Tararova·N D Aksenov·V A Pospelov·T V Pospelova
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Abstract

The capability of REF cells transformed by EA + E1B-19 kDa and EA + cHa-ras oncogenes to realize the G1/S cell cycle arrest upon serum starvation was studied. The amount of cyclin-kinase inhibitor protein p27/Kip was shown to increase in both normal and transformed cells. However, the p27/Kip-bound cyclin-kinase complexes of transformed cells were found to be active, implying the functional inactivation of p27/Kip inhibitor. Nevertheless, in contrast to E1A + cHa-ras transformants, E1A + E1B-19 kDa transformants undergo the G1 cell cycle arrest. The G1 cell cycle block correlates with the decrease in cyclinE-Cdk2 activity. Since cyclinE-Cdk2 complexes need Thr-160 phosphorylation of Cdk2 by CAK-kinase for full activity, we have analysed the Cdk-7 associated activity upon serum starvation using gst-Cdk2 as a substrate. Serum starvation did not affect CAK activity either in E1A + cHa-ras or in E1A + E1B-19 kDa transformants. Thus, selective suppression of cyclineE-Cdk2 activity in E1A + E1B-19 kDa transformants upon serum starvation does not arise from the action of cyclin-kinase inhibitors, or from change in CAK activity.

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Adenovirus E1A ProteinsAdenovirus E1B ProteinsAnimalsCell CycleCell Cycle ProteinsCell Line, TransformedCell Transformation, NeoplasticCell Transformation, ViralCulture Media, Serum-FreeCyclin-Dependent Kinase Inhibitor p27Cyclin-Dependent KinasesEmbryo, MammalianFibroblastsG1 PhaseGenes, rasRatsS PhaseSignal TransductionTumor Suppressor ProteinsEnglish AbstractJournal Article

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A I Brichkina, N D Tararova, N D Aksenov, V A Pospelov, T V Pospelova. 2001. [Rat embryo fibroblasts transformed by complementation with oncogenes E1A+E1B-19 and E1A+cHa-ras differ in the ability to realize the G1/S block in serum free media].. https://pubmed.ncbi.nlm.nih.gov/11840777/

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