Yagi T, Takebe H
Department of Molecular Oncology, Faculty of Medicine, Kyoto University.
Jpn J Cancer Res. 1989 Aug;80(8):754-8. doi: 10.1111/j.1349-7006.1989.tb01710.x.
The effect of UV irradiation on the rate of DNA synthesis was compared among normal human, xeroderma pigmentosum (XP, group A and variant) and mouse cells with and without caffeine in the culture medium after UV irradiation. At the same levels of survival, approximately 37%, all cells showed reduction in the rate of synthesis 0-3 h after UV irradiation followed by a recovery to normal or near-normal level 12 h later. In the presence of caffeine, no change in the recovery patterns was observed in normal human and XP A cells. XP variant cells and mouse cells showed little or no recovery in the presence of caffeine even after 12 h, when full recovery was obtained without caffeine. XP variant and mouse cells appear to have a common response in that post-irradiation treatment with caffeine inhibits reinitiation of UV-reduced DNA replication. Enhancement by caffeine of UV-killing in XP variant and mouse cells may be due to the retarded resumption of DNA replication.
比较了紫外线照射对正常人、着色性干皮病(XP,A组和变异型)以及小鼠细胞DNA合成速率的影响,这些细胞在紫外线照射后,培养基中添加或不添加咖啡因。在相同的存活率水平下,约37%时,所有细胞在紫外线照射后0 - 3小时内合成速率均降低,随后在12小时后恢复到正常或接近正常水平。在咖啡因存在的情况下,正常人及XP A细胞的恢复模式未观察到变化。XP变异型细胞和小鼠细胞在咖啡因存在时,即使12小时后也几乎没有或没有恢复,而在无咖啡因时可完全恢复。XP变异型细胞和小鼠细胞似乎有共同的反应,即紫外线照射后用咖啡因处理会抑制紫外线降低的DNA复制的重新起始。咖啡因增强XP变异型细胞和小鼠细胞的紫外线杀伤作用可能是由于DNA复制的恢复受阻。