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Identifying the Effects of BRCA1 Mutations on Homologous Recombination using Cells that Express Endogenous Wild-type BRCA1
Published on: February 18, 2011
Retrovirally mediated wild-type p53 restores S-phase modulation without inducing WAF1 mRNA in breast carcinoma cells
I B Runnebaum1, S Wang, R Kreienberg
1Department of Obstetrics and Gynecology, University of Ulm, Germany.
Abstract:
The mechanism of negative growth regulation by the nuclear phosphoprotein p53 in breast cancer cells may rely on its role as a transcriptional activator of cell cycle-related genes. We have tested this hypothesis using retrovirally transduced wild-type (wt) p53 in breast cancer cell lines containing homozygously endogenous mutant (mt) p53. Restoring the expression of wt p53, the percentage of cells in S phase was reduced, G1/S transition was slowed, and progression through S was restrained. The fraction of cells with a flattened "Cdk-minus" phenotype increased 5- to 10-fold. High constitutive mRNA expression of the cyclin-Cdk inhibitor WAF1 in MDAMB231 cells was not induced upon restored wt p53 expression suggesting a p53-independent pathway in the regulation of WAF1 mRNA expression. Wt p53 acted trans-dominantly in the presence of accumulating mt p53 and installed a modulation of G1/S transition and S phase progression independent of WAF1 expression.
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