Analysis of the ARF/p53 Pathway During Oncogenic Stimulation

Abstract : This report describes the research accomplishments/findings covering the above indicated period and outlined in the approved statement of work. In short, we have locally manufactured, tested and successfully used the spotted cDNA microarray chips to analyze gene expression profiles of E1A induced primary mouse fibroblasts either wild-type or deficient for the ARF and/or p53 genes. We found that the ElA oncoprotein regulates the expression of a myriad of targets involved in a diversity of functions such as apoptosis, cell cycle progression, checkpoint control, DNA replication, angiogenesis, biosynthesis, as well as structural and cytoskeletal elements. Our results revealed the pleiotropic role of El A and produced a databank of potential apoptotic targets that can be studied and characterized. Following up on some targets, we demonstrated that ElA can coordinately up-regulate caspase expression through E2F via a direct transcriptional mechanism, providing therefore an example of how apoptosis can be hardwired' to cell-cycle progression. Importantly, we also showed that, p53-generated signals resulting in caspase activation (for example, cytochrome C release from mitochondria) cooperate with p53-independent increases in caspase expression to induce apoptosis, implying that oncogene-induced apoptosis proceeds through a highly coordinated series of events.