Abstract
A major goal of current cancer research is to understand the functional consequences of mutations in recombinational DNA repair genes. The introduction of artificial recombination substrates into living cells has evolved into a powerful tool to perform functional analysis of DNA double strand break (DSB) repair. Here, we review the principles and practice of current plasmid assays with regard to the two major DSB repair pathways, homologous recombination and nonhomologous end-joining. A spectrum of assay types is available to assess repair in a wide variety of cell lines. However, several technical challenges still need to be overcome. Understanding the alterations of DSB repair in cancers will ultimately provide a rational basis for drug design that may selectively sensitize tumor cells to ionizing radiation and chemotherapy, thereby achieving therapeutic gain.
Highlights
The past few years have seen an explosive increase in the understanding of both the molecular mechanisms and the genetic determinants of recombinational DNA repair
The introduction of artificial recombination substrates into living cells has evolved into a powerful tool to perform functional analysis of DNA double strand break (DSB) repair
We could show that BRCA2- and BRCA1-deficient tumor cells are defective in homology-mediated recombination between a chromosomal and an extrachromosomal substrate by one order of magnitude ([29] and unpublished data from our lab)
Summary
The past few years have seen an explosive increase in the understanding of both the molecular mechanisms and the genetic determinants of recombinational DNA repair. Sporadic mutations and polymorphisms in a variety of genes involved in recombination have been found in normal tissues and in malignant tumors, including BRCA1, RAD54, RAD52, and XRCC3 [3, 4]. It is largely unknown what the functional significance of these alterations is. There is tremendous interest in a better understanding of the intricate protein networks in which these and other gene products cooperate This knowledge will have significant implications for cancer prevention and treatment. For details on mechanisms and genetic determinants of HR and NHEJ, the reader is referred to excellent recent review articles [1, 4, 5] (including this issue of JBB, DNA Damage, Repair, and Diseases)
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