Richards R G, Brown O E, Sedwick W D
Basic Life Sci. 1985;31:149-62. doi: 10.1007/978-1-4613-2449-2_9.
Treatment of B and T lymphoblastoid cell lines (SB and MOLT-4, respectively) and a promyelocytic leukemia cell line (HL-60) with the lipid soluble antifolate, 2,4-diamino-5-methyl-6-(2',5'-dimeth-oxybenzyl) -pyrido (2,4-d) pyrimidine (BW301U), led to drug dose-dependent inhibition of [3H]deoxyuridine (dU) incorporation into DNA as thymidine, and to misincorporation of [3H]dU as dUMP. After a 15 min preincubation with up to 50 microM BW301U and a further 15 min incubation after addition of [3H]dU, the number of alkaline labile apyrimidinic sites increased with increasing drug dose, as demonstrated by alkaline sucrose gradient analysis. Significantly, new replication of DNA was inhibited only approximately 50% by 50 microM BW301U when [3H]dU incorporation was greater than or equal to 97% inhibited. Additional preliminary findings suggest that newly replicated DNA containing misincorporated dUMP is rapidly degraded in vivo by extensive excision-repair processes.
用脂溶性抗叶酸剂2,4-二氨基-5-甲基-6-(2',5'-二甲氧基苄基)-吡啶并(2,4-d)嘧啶(BW301U)处理B和T淋巴母细胞系(分别为SB和MOLT-4)以及早幼粒细胞白血病细胞系(HL-60)，导致药物剂量依赖性地抑制[3H]脱氧尿苷(dU)作为胸苷掺入DNA，并导致[3H]dU错误掺入为dUMP。在用高达50 microM BW301U预孵育15分钟并在加入[3H]dU后再孵育15分钟后，碱性蔗糖梯度分析表明，随着药物剂量增加，碱性不稳定无嘧啶位点的数量增加。值得注意的是，当[3H]dU掺入被抑制大于或等于97%时，50 microM BW301U仅抑制约50%的DNA新复制。其他初步研究结果表明，含有错误掺入dUMP的新复制DNA在体内通过广泛的切除修复过程迅速降解。
