Mutations and Cell Defenses

Abstract

The information required for the development and growth of an organism is encoded in its deoxyribonucleic acid (DNA), the genetic material. Mutations, or changes to the information content of a cell’s DNA, can result in developmental defects or genetic diseases that may occur at any point in one’s life. Cancers are genetic diseases resulting from mutations that disrupt the ability of cells and tissues to control their own growth and proliferation. Given the critical importance of maintaining the integrity of the information encoded by DNA, evolution has resulted in various means by which a cell can either avoid mutations resulting from DNA damage, or repair damage once it has occurred. Despite the fact that all cells suffer continuous DNA damage caused either by normal metabolic processes, e.g., DNA replication and cell division, or by exposure to various environmental carcinogens, e.g. sunlight, tobacco and car exhaust, cells have a remarkable ability to both minimize the rate of mutation and to repair DNA damage. Human cells have five distinct enzyme systems that repair DNA damage, and the importance of each of these “DNA repair pathways” is highlighted by the fact that defects in any of the five result in higher incidences of specific types of cancers. In this Chapter we describe how each of these pathways operates to protect cells from acquiring mutations. Additionally, we briefly discuss recent ideas supporting an important role for stem cells in limiting the cancer potential of cells and tissues that have accumulated DNA damage. Gildemeister, O.S., Sage, J.M. and Knight, K.L. (2009) Mutations and Cell Defenses, in Pardee, A.D. and Stein, G.S. (eds.), The Biology and Treatment of Cancer: Understanding Cancer, Hoboken, New Jersey: John Wiley & Sons, Inc., 123-142. ISBN 0470009586, 9780470009581.