雷公藤内酯对L_(1210)细胞补救通路DNA合成的影响

Effects of Triptolide on DNA Synthesis in Salvage Pathway in L_(1210) Cells

用[~3 H]TdR参入法发现雷公藤内酯对L_(1210)细胞TdR转运有较强的抑制作用,而对TdR磷酸化的影响较弱。通过分析药物对DNA溶液粘滞性的影响、药物对DNA平衡透析及药物与DNA作用后的紫外光谱与荧光光谱变化等,均未发现药物与DNA之间存在相互作用。从药物对无细胞体系DNA合成无明显影响可进一步证实该药对DNA模板功能及DNA聚合酶α均无明显影响。因此对补救通路DNA合成的抑制,主要缘于该药对细胞核苷转运的抑制。

The Effects of triptolide on thymidine transport and phosphorylation were studied by using incor- poration of ~3H-TdR into cells and isolating products of phosphorylation. After L_(1210) cells were expased to triptolide 0.2～20 μg/ml for 3 h,thymidine transport in cells was inhibited by 29.75 %～58.6 %. In the same conditions the phosphorylation of thymidine in cells was inhibited slightly,and the highest inhibitory rate was 35%. The methods of shift of absorption spectrum, shift of fluorescence emission spectrum and excition spectrum,viscosity of DNA solution and equilibrium dialysis of DNA to triptolide were used to study interaction of the drug with DNA. The results suggest that the inhibitory action of triptolide on DNA synthesis in cells was not due to direct damage to DNA template. DNA polymerase α isolated from L_(1210) cells was used to study the effect of triptolide on polymerization of deoxyriboun- cleoside triphosphates(dNTPs) into DNA. The activity of the enzyme was found not to be inhibited by preincubation of triptolide 100 μg/ml with the enzyme at 4℃ for 10 h or 37℃ for 1 h. It is concluded that the mechanism of triptolide on inhibition of DNA synthesis in salvage pathway in L_(1210) cells might be mainly due to the inhibition of nucleotides uptake in L_(1210) cells.