Fernandes R S, Cotter T G
Department of Biology, St. Patrick's College, Maynooth, County Kildare, Ireland.
Anticancer Res. 1993 Sep-Oct;13(5A):1253-9.
Cytotoxic drugs induce apoptosis in human tumour cell lines and this is characterised by fragmentation of the cell's DNA into nucleosome size units or multiples thereof. In the present study we demonstrated that nuclei isolated from three human haematopoietic cell lines, HL-60, U937 and K562, contain an endonuclease that is independent of Ca++, Mg++ and Na+ ions for its activity. This contrasts with what has previously been shown for a number of rodent cell types in which apoptosis has been studied. The lack of ion sensitivity is also found in the nuclei of peripheral blood granulocytes, indicating the data are not peculiar to cell lines. In addition, this particular endonuclease activity does not appear to be sensitive to the endonuclease inhibitor aurintricarboxylic acid. The previously demonstrated lack of calcium flux in HL-60 cells undergoing apoptosis, and the current demonstration of a lack of an endonuclease dependent on this ion for its activity, suggest that the mechanism of apoptosis in human cells may be different from that in rodent cells.
细胞毒性药物可诱导人肿瘤细胞系发生凋亡，其特征是细胞DNA断裂成核小体大小的单位或其倍数。在本研究中，我们证明从三种人造血细胞系HL-60、U937和K562中分离出的细胞核含有一种核酸内切酶，其活性不依赖于Ca++、Mg++和Na+离子。这与先前对一些研究过凋亡的啮齿动物细胞类型的研究结果形成对比。在外周血粒细胞的细胞核中也发现了缺乏离子敏感性的情况，这表明这些数据并非细胞系所特有。此外，这种特定的核酸内切酶活性似乎对核酸内切酶抑制剂金精三羧酸不敏感。先前证明HL-60细胞在凋亡过程中缺乏钙通量，以及目前证明存在一种活性不依赖于该离子的核酸内切酶，这表明人细胞凋亡的机制可能与啮齿动物细胞不同。
