The P53 Tumor Suppressor Pathway And Cancer

The current year (2004) marks the Silver Anniversary of the discovery of the p53 tumor suppressor. The emerging ?eld ?rst considered p53 as a viral antigen and then as an oncogene that cooperates with activated ras in transforming primary cells in culture. Fueling the concept of p53 acting as a transforming factor, p53 expression was markedly elevated in various transformed and tumorigenic cell lines when compared to normal cells. In a simple twist of fate, most of the studies conducted in those early years inadvertently relied on a point mutant of p53 that had been cloned from a normal mouse genomic library. A bona ?de wild-type p53 cDNA was subsequently isolated, ironically, from a mouse teratocarcinoma cell line. A decade after its discovery, p53 was shown to be a tumor suppressor that protects against cancer. It is now recognized that approximately half of all human tumors arise due to mutations within the p53 gene. As remarkable as this number may seem, it signi?cantly underrepresents how often the p53 pathway is targeted during tumorigenesis. It is my personal view, as well as many in the p53 ?eld, that the p53-signaling pathway is corrupted in nearly 100% of tumors. If you are interested in understanding cancer and how it develops, you must begin by studying p53 and its pathway. After demonstrating that p53 functions as a tumor suppressor the ?eld exploded and p53 became a major focus of scientists around the world.

This book provides the readers with an overview of research on p53, which has been shown to play a role in numerous crucial biological pathways in normal and cancer cells. Leading scientist in the field, who have all made direct contributions to the understanding of the molecular events underpinning p53 function, have been invited to contribute the various chapters, which discuss the current knowledge of the signaling cascades that are activated by mutations in p53 and overexpression of MDM2, frequently found in human cancer and are major causes of oncogenesis. This book features chapters on the molecular basis of oncogenesis induced by gain of function mutation of p53, signaling pathways induced by MDM2 overexpression, control of mutant or wild-type p53 function by MDM2 and MDMX, p53 mutation in hereditary cancer and structural aspects that activate mutant p53 which can be targeted by drug therapy. This book should be useful for scientists at all levels.

A tumour suppressor gene is a gene that reduces the probability that a cell in a multicellular organism will turn into a tumor cell. A mutation or deletion of such a gene will increase the probability of the formation of a tumor. Unlike oncogenes, tumor suppressor genes generally follow the 'two-hit hypothesis', which implies that both alleles that code for a particular gene must be affected before an effect is manifested. This is due to the fact that if only one allele for the gene is damaged, the second can still produce the correct protein. However, there are cases where mutations in only one allele will cause an effect. A notable example is the gene that codes for p53. Tumor suppressor genes, or more precisely, the proteins for which they code, either have a dampening or repressive effect on the regulation of the cell cycle or promote apoptosis, and sometimes do both. This book presents new and important research from throughout the world.

This book is about the p53 gene, one of the most frequently mutated or deleted genes in human cancers. The frequent occurrence of inactivated p53 implicates this gene product in the genesis of many human cancers. The p53 gene can suppress the growth of cancer cells and the transformation process by oncogenes. The p53 protein is a transcription factor that can repress or activate promoters containing one of three p53 DNA-binding motifs. The activity of p53 is regulated by phosphorylation and other transcription factors. Replacement of the p53 function or restoration of the p53 biochemical pathway is a focus of gene therapy.

p53 has emerged as a key tumor suppressor and important target for novel cancer therapy. This book, written by world-leading p53 researchers including many of those who have shaped the field over the past 25 years, provides unique insights into the progress of the field and the prospects for better cancer diagnosis and therapy in the future.

This project follows on the success of the book "25 years of p53", published by Springer in 2006. Since this publication, there have been considerable advances on the potential application of p53 into the clinics. The goal of this book is to capture these developments and to appeal to a clinical and medical audience beyond the one which was the primary target of "25 years of p53".

It has become clear that tumors arise from excessive cell proliferation and a c- responding reduction in cell death. Tumors result from the successive accumulation of mutations in key regulatory target genes over time. During the 1980s, a number of oncogenes were characterized, whereas from the 1990s to the present, the emphasis shifted to tumor suppressor genes (TSGs). It has become clear that oncogenes and tumor suppressor genes function in the same pathways, providing positive and ne- tive growth regulatory activities. The signaling pathways controlled by these genes involve virtually every process in cell biology, including nuclear events, cell cycle, cell death, cytoskeletal, cell membrane, angiogenesis, and cell adhesion effects. Tumor suppressor genes are mutated in hereditary cancer syndromes, as well as somatically in nonhereditary cancers. In their normal state, TSGs control cancer development and p- gression, as well as contribute to the sensitivity of cancers to a variety of therapeutics. Understanding the classes of TSGs, the biochemical pathways they function in, and how they are regulated provides an essential lesson in cancer biology. We cannot hope to advance our current knowledge and to develop new and more effective therapies without understanding the relevant pathways and how they influence the present approaches to therapy. Moreover, it is important to be able to access the powerful tools now available to discover these genes, as well as their links to cell biology and growth control.