3'-Azido-3'-deoxythymidine potently inhibits protein glycosylation. A novel mechanism for AZT cytotoxicity

3'-Azido-3'-deoxythymidine (AZT) is one of the primary chemotherapeutic agents used in the treatment of human immunodeficiency virus (HIV) infection. Unfortunately, AZT therapy is accompanied by severe side effects. Using Golgi-enriched membrane fractions, we have determined that 3'-azido-3'-deoxythymidine monophosphate, the primary AZT metabolite in treated cells, potently inhibits protein glycosylation. This inhibition results from direct competition with several pyrimidine-sugars for transport into Golgi membranes. This potential mechanism of cytotoxicity does not involve 3'-azido-3'-deoxythymidine triphosphate, the AZT metabolite most likely responsible for its antiviral effects; thus, it may be possible to develop novel therapeutic strategies that prevent inhibition of glycosylation without affecting the anti-HIV properties of AZT.