Gene expression analysis of U251 human glioblastoma cell line

The human TP53 gene is frequently mutated in tumors and cell lines. Unlike other tumor suppressors that are commonly inactivated by deletions or nonsense mutations, the majority of p53-mutations are missense point mutations that result in the expression of a full-length protein with an altered amino acid that has lost sequence specific DNA-binding. Expression of mutant p53 (mutp53) confers advantages to tumor cells and transcriptional regulation of several genes mediating the beneficial effects has been shown to play a role. However, molecular mechanisms of transcriptional regulation by mutp53 are still poorly understood. We used the glioblastoma-derived U-251 MG human cell line endogenously expressing mutp53 protein (R273H mutation) to analyze gene expression profiles on Agilent Whole Human Genome Microarray after transient and stable depletion of mutp53 expression. Gene expression data was correlated with a ChIP study on a custom tiling array to understand the contribution of endogenously expressed mutp53 to transcriptional regulation. This series of microarray experiments contains the gene expression profiles of glioblastoma-derived U-251 MG human cell lines engineered to constitutively express a p53-specific shRNA or scrambled control shRNA. To reverse the effect of mutp53 depletion, stable clones were modified by stable integration of a mutp53-R273H expression construct or empty pCDNA3 vector as a control. In addition, we performed gene expression analysis of U-251 MG cells transiently transfected with p53-specific siRNA or control siRNA (3 biological replicates each).