ARSENITE ENHANCES DNA DOUBLE-STRAND BREAKS AND CELL KILLING OF METHYL METHANESULFONATE-TREATED CELLS BY INHIBITING THE EXCISION OF ALKALI-LABILE SITES
ARSENITE ENHANCES DNA DOUBLE-STRAND BREAKS AND CELL KILLING OF METHYL METHANESULFONATE-TREATED CELLS BY INHIBITING THE EXCISION OF ALKALI-LABILE SITES
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DOI：
10.1016/0921-8777(93)90054-k
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发表时间：
1993-06-01
期刊：
影响因子：
--
通讯作者：
JAN, KY
中科院分区：
文献类型：
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作者：
LEECHEN, SF;GURR, JR;JAN, KY
碱洗脱法DNA链断裂分析表明，亚砷酸钠对甲基甲烷磺酸(MMS)处理的中国仓鼠卵巢细胞DNA修复有抑制作用。比较用缓冲液pH 12.1洗脱36min和用缓冲液pH 12.4洗脱12h的图谱，发现在MMS和亚砷酸盐的联合处理中，碱不稳定部位的增加比坦率断裂更多。低剂量的MMS和亚砷酸盐可促进细胞的碱不稳定部位，而增加MMS和亚砷酸盐的浓度才能增强细胞的直链断裂。在含亚砷酸盐的培养液中孵育18或12h但不少于6h后，MMS处理的细胞可检测到双链断裂，而MMS损伤细胞经亚砷酸盐处理3h后未检测到双链断裂；然而，在无亚砷酸盐的培养液中进一步孵育18h后，这些细胞检测到双链断裂。因此，亚砷酸盐对甲基化碱基切除的抑制可能在亲本链中积累了大量的碱不稳定部位，DNA复制可能会在非甲基化的子链中产生断裂。双链断裂可能是由于父链和子链之间的缝隙重叠和/或复制后修复造成的。这些双链断裂可能导致协同细胞死亡，就像亚砷酸盐处理MMS损伤细胞1或3小时所观察到的那样。
Analysis of DNA strand breaks by alkaline elution indicates that DNA repair of Chinese hamster ovarY cells treated with methyl methanesulfonate (MMS) was inhibited by sodium arsenite. Comparing the profiles of a 36-min elution with buffer pH 12.1 and a 12-h elution with buffer pH 12.4 revealed that alkali-labile sites were increased more than frank breaks in the combined treatment with MMS plus arsenite. Enhancement of alkali-labile sites was detected with low doses of MMS and arsenite, whereas enhancement of frank breaks required higher doses of MMS and arsenite.Double-strand breaks were detected after incubating the MMS-treated cells in an arsenite-containing medium for 18 or 12 h but not less than 6 h. No double-strand breaks were detected when MMS-damaged cells were posttreated with arsenite for 3 h; however, double-strand breaks were detected after further incubating these cells in arsenite-free medium for 18 h. Thus, inhibition of arsenite on the excision of methylated bases may have accumulated a large number of alkali-labile sites in the parental strands, and DNA replication may then generate breaks in the non-methylated daughter strands. Double-strand breaks may result from overlapping gaps between the parental and daughter strands and/or postreplication repair. These double-strand breaks may then result in the synergistic cell death as observed with posttreatment of MMS-damaged cells with arsenite for 1 or 3 h.