Identification genes involved in p53-dependent apoptosis in response to different types of cellular stress using array analysis
Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institute, Stockholm, Sweden
The p53 tumor suppressor triggers cell cycle arrest or apoptosis in response to different stress stimuli, including DNA damage, activated oncogenes, and hypoxia. p53-induced cell cycle arrest and apoptosis are dependent on p53:s ability to regulate specific target genes. In order to compare patterns of p53-dependent transactivation and transrepression in response to different types of cellular stress and identify novel p53 target genes, we have used a cDNA micro array approach in collaboration with Joakim Lundberg at Royal Institute of Technology, Stockholm. HCT116 wt p53+/+, colon carcinoma cells and the p53 null isogenic line HCT 116 p53 -/- were treated with UV light or exposed to hypoxic conditions that induce p53 protein levels at different time points. p53 induction was confirmed by both immunostaining and Western blotting. RNA from these cells was hybridized to cDNA chips containing 20,000 known genes. In parallel, we have studied p53-mediated gene regulation using a much simpler approach, a so called SuperArray filter which contains probes for 96 p53 target genes or key genes in the p53 pathway. Our results from both approaches so far demonstrate that several known p53 target genes (for example, p21, Bax, and Wig1) are induced, both by UV and hypoxia. However, a number of genes with unknown function in the p53 pathway are induced or repressed upon activation of wt p53 in these cells. Furthermore, our results indicate that diverse groups of genes are differentially regulated in response to UV and hypoxia. These genes are involved in cell cycle regulation, apoptosis, DNA mismatch repair and signal transduction. Genes of particular interest are now being further analyzed using different molecular and cellular strategies.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 998 (Signaling pathways - Part III).