Determinants of deoxyadenosine toxicity in hybrids between human T- and B- lymphoblasts as a model for the development of drug resistance in T-cell acute lymphoblastic leukemia.
Determinants of deoxyadenosine toxicity in hybrids between human T- and B- lymphoblasts as a model for the development of drug resistance in T-cell acute lymphoblastic leukemia.
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发表时间：
1985-04
期刊：
影响因子：
11.2
通讯作者：
J. Kurtzberg;M. Hershfield
中科院分区：
文献类型：
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作者：
J. Kurtzberg;M. Hershfield
在腺苷脱氨酶的有效抑制剂2 '-脱氧共形霉素存在下，培养的人T淋巴母细胞样细胞系比B细胞系对2'-脱氧腺苷更敏感。这种差异与T淋巴母细胞积累细胞毒性水平的dATP的效率更高有关，dATP来源于腺苷脱氨酶底物2 '-脱氧腺苷（dAdo）。以前的工作表明，培养的T-和B-淋巴母细胞样细胞系的dATP积累的差异不能解释为这些细胞的细胞质提取物中dATP磷酸化或dAdo核苷酸（dAXP）降解活性水平的巨大差异，尽管已经提出完整的B细胞系可能比T细胞系更快地分解代谢细胞内dAXP。为了进一步研究T和B淋巴母细胞中dAdo敏感性的决定因素，我们研究了人T和B细胞系CEM和WI-L2以及这些细胞系融合产生的杂交体中的dAdo和dAXP代谢。通过营养研究和细胞表面抗原、DNA含量和酶活性的分析建立了融合产物的杂交性质。我们发现，WI-L2 X CEM杂交体和另一种来源于SB人B细胞系与CEM融合的T X B杂交体对dAdo的敏感性比CEM低30至40倍，对dAdo类似物9-β-D-阿拉伯呋喃糖基腺嘌呤的敏感性低约10倍，或者与它们的B细胞亲本系一样具有抗性。我们的研究证实CEM从dAdo贪婪地积累dAXP，但不分解代谢细胞内dAXP。相比之下，WI-L2、SB和WI-L2 X CEM和SB X CEM杂交体快速降解细胞内dAXP，这限制了它们进行dAXP库扩增的能力。在T X B杂种中dAXP分解代谢活性的表达表现为显性机制，赋予T X B杂种对dAdo和dAdo相关核苷的抗性。据推测，细胞融合可能在肿瘤的进展中起作用，并有助于构成克隆性肿瘤的细胞之间的多样性。我们推测，恶性T淋巴母细胞与活化B细胞的融合可能是急性T细胞白血病耐药性演变的一种机制。
Cultured human T-lymphoblastoid cell lines are more sensitive than B-cell lines to 2'-deoxyadenosine in the presence of 2'-deoxycoformycin, a potent inhibitor of adenosine deaminase. This difference is related to the greater efficiency with which T-lymphoblasts accumulate cytotoxic levels of dATP derived from the adenosine deaminase substrate 2'-deoxyadenosine (dAdo). Previous work has shown that differences in dATP accumulation by cultured T- and B-lymphoblastoid cell lines cannot be explained by large differences in the levels of dAdo-phosphorylating or dAdo nucleotide (dAXP)-degrading activities in cytoplasmic extracts of these cells, although it has been proposed that intact B-cell lines may catabolize intracellular dAXP more rapidly than do T-cell lines. To further examine the determinants of dAdo sensitivity in T- and B-lymphoblasts, we have studied dAdo and dAXP metabolism in the human T- and B-cell lines CEM and WI-L2 and in hybrids generated by fusion of these cell lines. The hybrid nature of the fusion products was established by nutritional studies and by analyses of cellular surface antigens, DNA content, and enzymatic activities. We found that WI-L2 X CEM hybrids and another T X B hybrid derived from fusion of the SB human B-cell line with CEM were 30- to 40-fold less sensitive to dAdo and about 10-fold less sensitive to the dAdo analogue 9-beta-D-arabinofuranosyladenine than was CEM, or about as resistant as were their B-cell parental lines. Our studies confirm that CEM avidly accumulates dAXP from dAdo but does not catabolize intracellular dAXP. In contrast, WI-L2, SB, and WI-L2 X CEM and SB X CEM hybrids rapidly degraded intracellular dAXP, which limited their ability to undergo dAXP pool expansion. Expression of dAXP catabolic activity in T X B hybrids behaved as a dominant mechanism, conferring resistance to dAdo- and dAdo-related nucleosides to T X B hybrids. It has been postulated that cell fusion may play a role in the progression of tumors and contribute to diversity among the cells that compose clonal tumors. We have speculated that fusion of a malignant T-lymphoblast with an activated B-cell might be a mechanism for the evolution of drug resistance in acute T-cell leukemia.