Activity of uridine kinase in different lines of AKR leukemic mice and its relation to chemotherapy with 5-azacytidine.

The sensitivity of different wild-type and 5-azacytidine-resistant lines of AKR leukemic mice to 5-azacytidine varies in relation to the activity of uridine kinase isolated from corresponding leukemic livers. The enhancement of liver uridine kinase activity observed in leukemic mice following the administration of a single dose of 5-azacytidine is accounted for by the presence of hepatocytes in infiltrated leukemic livers. The optimal schedule for the treatment of AKR leukemic mice with 5-azacytidine requires equally divided doses administered daily and not an initial high dose followed by low doses.