Genomic Instability, DNA Repair Pathways and Cancer

Genetic information, in the form of DNA, must be protected for expression within the cell and transfer between generations. While a number of mechanisms have been developed to allow for genetic diversity, multiple and redundant mechanisms work to avoid errors during DNA synthesis before cell duplication and/or to avoid the impact of mutagens from endogenous or exogenous sources. The DNA sequence can be changed as the result of copying errors introduced by DNA polymerases during replication and by environmental agents such as mutagenic chemicals and certain types of radiation. If DNA sequence changes, whatever their cause, are left uncorrected, both growing and nongrowing somatic cells could accumulate so many mutations that they could no longer function. Thus, the correction of DNA sequence errors in all types of cells is important for survival (1).