O6-alkylguanine-DNA alkyltransferase inactivation in cancer chemotherapy.

The protein O(6)-alkylguanine-DNA alkyltransferase is the basis of an important process for repairing damage to cellular DNA, which renders cells resistant to drugs that alkylate at the O(6)-position of guanine residues. The development of various pseudosubstrates which inactivate this protein is reviewed, from a chemical standpoint. Study of the influence of pseudosubstrate molecular structure on their interaction with the active site cysteine has progressed together with direct investigation of protein structure. Combination therapy using a powerful inactivator with a suitable alkylating agent shows great clinical promise in the treatment of cancer, particularly when some degree of selectivity is possible.