胆碱与叶酸组合对人成淋巴细胞株DNA损伤效应

目的探讨叶酸充足时胆碱缺乏对人成淋巴细胞株的遗传损伤效应。方法在甲硫氨酸(Met)浓度为50μmol/L条件下,设置0～21.5μmol/L的胆碱与30、60、120、240nmol/L的叶酸(folic acid,FA)组成不同浓度组合,培养人成淋巴细胞株9d后,利用胞质阻断微核细胞组分析(CBMNCyt),评价上述组分缺乏诱发的微核化双核细胞(MNedBNC)、核质桥(NPB)及核芽(NBUD)千分率。结果各叶酸浓度下,低浓度胆碱组(0、3、6μmol/L)与高浓度胆碱组(12、18、21.5μmol/L)之间的MNedBNC及NBUD千分率差异有统计学意义(P0.001);低叶酸情况下(30、60nmol/L),12μmol/L胆碱以上的NPB千分率显著降低(P0.001),而高叶酸情况下(120、240nmol/L)各胆碱浓度之间的NPB率无显著差异。胆碱和叶酸对MNedBNC、NPB及NBUD变异的贡献率均达到了极显著(P0.001)。结论胆碱不足对人成淋巴细胞株造成遗传损伤,该细胞株基因组的稳定需要叶酸和胆碱浓度分别维持在120nmol/L和12μmol/L以上。

EFFECT OF CHOLINE AND FOLIC ACID ON DNA DAMAGE IN HUMAN LYMPHOBLAST CELL LINE

Objective To study whether human lymphoblast cell line cultured by choline deficient medium had effects on DNA damage despite of sufficient folic acid.Method Lymphoblast cells were cultured in RPMI-1640 medium which was modified with 24 different combination of choline(0,3,6,12,18,21.5 μmol/L),folic acid(FA,30,60,120,240 nmol/L) and methionine(50 μmol/L).After 9 d cytokinesis-block micronucleus cytome assay(CBMN Cyt) was used to evaluate the frequencies of genotoxic indices including micronucleated binucleated cell(MNed BNC),nucleoplasmic bridge(NPB) and nuclear bud(NBUD).Results The statistic significance of MNed BNC‰ and NBUD‰ was found between low level(0-6 μmol/L) and high level of choline(12-21.5 μmol/L) in all concentrations of folic acid(P<0.001).In 30 and 60 nmol/L FA,NPB was significantly decreased when the choline concentrations were 12μmol/L(P<0.001),but in 120 and 240 nmol/L FA,the frequencies of NPB among six groups of choline were insignificantly different.Choline and folic acid also had significant impacts on variation of all genotoxic indices(P<0.001).Conclusion Choline deficiency could bring DNA damage in human lymphoblast cell line.This preliminary investigation suggested that one should consider not only supplying adequate amounts of folic acid(>120nmol/L),but also maintaining choline concentration >12 μmol/L.