An Oligonucleotide Crosslinking Assay for the Analysis of Individual DrugBinding Sites

Many agents used in the treatment of cancer are bifunctional in nature and are therefore able to crosslink cellular macromolecules. Despite these nonspecific reaction mechanisms, DNA appears to be the most important cellular target for many of these anticancer agents. The formation of DNA interstrand crosslinks have been suggested to be the most relevant cytotoxic lesions imparted by these agents (l –3 ), and this is presumably achieved by inhibition of the DNA-dependent polymerases and other proteins involved in the rephcation and transcriptional processes. Furthermore, it has also been documented that DNA interstrand crosslinks are more difficult to repair than monoadducts (by the various DNA repair mechanisms), thus leading to a greater cytotoxlc response (4 ).