Cell density-dependent VP-16 sensitivity of leukaemic cells is accompanied by the translocation of topoisomerase IIalpha from the nucleus to the cytoplasm.
Cell density-dependent VP-16 sensitivity of leukaemic cells is accompanied by the translocation of topoisomerase IIalpha from the nucleus to the cytoplasm.
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白血病细胞的细胞密度依赖性 VP-16 敏感性伴随着拓扑异构酶 IIα 从细胞核易位到细胞质。
DOI：
10.1046/j.1365-2141.2000.01832.x
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发表时间：
2000
影响因子：
6.5
通讯作者：
Sullivan,DM
中科院分区：
文献类型：
--
作者：
Valkov,NI;Gump,JL;Engel,R;Sullivan,DM
几种白血病和骨髓瘤细胞系(CCRF、L1210、HL-60、KG-1a和RPMI8226)对VP-16的耐药性随着细胞密度的增加而增加，并在平台期细胞培养中达到最大值(克隆形成法和四甲基偶氮唑盐比色法)(3.5~39倍)。未转化的人成纤维细胞和中国仓鼠卵巢细胞对VP-16的耐药性分别为5倍和15倍。从LOG到平台期，CHO细胞和人成纤维细胞的拓扑异构酶(TOPO)IIα含量急剧下降，而白血病细胞中TOPO IIα和TOPO IIβ的细胞水平保持不变。然而，在白血病细胞中，由于该酶移位到细胞质隔室，核TOPO IIα含量下降。亚细胞分离实验、Western blotting分析和免疫细胞化学研究证实了这一点。通过免疫印迹和免疫荧光图像定量检测，平台期细胞组分中Topo IIα的含量从L1210细胞的18%到HL-60和8226细胞的50%不等。平台期细胞的胞质组分保持了Topo II的催化活性，通过动泡体DNA的降解来衡量。TOPO IIα的核浆比可能是决定白血病细胞对TOPO II抑制剂敏感性的关键。在多发性骨髓瘤患者血浆细胞中观察到Topo IIα的胞浆转运，可能与多发性骨髓瘤耐药有关。
The resistance of several leukaemic and myeloma cell lines (CCRF, L1210, HL‐60, KG‐1a and RPMI 8226) to VP‐16 was found to increase with cell density and to be maximal (3.5‐ to 39‐fold) in plateau phase cell cultures, as measured by clonogenic and MTT assays. Non‐transformed confluent Flow 2000 human fibroblasts and Chinese hamster ovary (CHO) cells were also five‐ and 15‐fold resistant to VP‐16 respectively. The transition from log to plateau phase was accompanied by a drastic decrease in topoisomerase (topo) IIα content in CHO cells and human fibroblasts, while the leukaemic cells maintained constant cellular levels of topo IIα and topo IIβ. However, the nuclear topo IIα content was found to decrease as a result of translocation of the enzyme to the cytoplasmic compartment in the leukaemic cells. This was confirmed by subcellular fractionation experiments, Western blotting analyses and immunocytochemistry studies. The quantity of topo IIα in plateau phase cytoplasmic fractions ranged from 18% in L1210 cells to 50% in HL‐60 and 8226 cells, as measured by both immunoblotting and quantification of the label in immunofluorescent images. The cytoplasmic fraction from plateau phase cells retained topo II catalytic activity, as measured by the decatenation of kinetoplast DNA. The nuclear–cytoplasmic ratio of topo IIα may be critical in determining the sensitivity of leukaemic cells to topo II inhibitors. Cytoplasmic trafficking of topo IIα was observed in plasma cells obtained from patients with multiple myeloma, and perhaps contributes to drug resistance in this disease.