当前位置： SCI文献检索 > CANCER CHEMOTHERAPY AND PHARMACOLOGY期刊下所有文献 > The role of deoxycytidine-metabolizing enzymes in the cytotoxicity induced by 3'-amino-2',3'-dideoxycytidine and cytosine arabinoside.

The role of deoxycytidine-metabolizing enzymes in the cytotoxicity induced by 3'-amino-2',3'-dideoxycytidine and cytosine arabinoside.

Abstract：

:The cellular metabolism of 3'-amino-2',3'-dideoxycytidine (3'-NH2-dCyd), a cytotoxic agent previously reported to be a poor substrate for purified Cyd/dCyd deaminase (dCydD), was compared with that of cytosine arabinoside (ara-C) in cells that displayed dCydD activity (HeLa) and in cells that did not (L1210). Growth inhibition induced by 3'-NH2-dCyd was dependent on the levels of anabolic enzymes, particularly dCyd kinase (dCydK), whereas cytotoxicity induced by ara-C was dependent on the expression of both anabolic and catabolic enzyme activities. Competition kinetics using purified enzyme revealed that the binding affinity of ara-C to dCydK was 5-fold that of the amino analog. However, this binding advantage is apparently offset in cells that contain high levels of dCydD, since the Ki values for this enzyme were 0.2 and 23 mM for ara-C and 3'-NH2-dCyd, respectively. This was reflected in the decrease in analog sensitivity observed between the two cell lines, whereby the concentrations of ara-C and 3'-NH2-dCyd required to inhibit growth by 50% were 200 and 7 times higher, respectively, in the dCydD-containing HeLa cells as compared with the dCydD-deficient L1210 cells. The metabolic stability and cytotoxicity of 3'-NH2-dCyd was independent of cell number. An unexpected finding was the extent to which the effectiveness of ara-C could be mitigated by the number of dCydD-containing cells. A completely cytotoxic concentration of ara-C was rendered nontoxic by a 10-fold increase in cell number. This observation was supported by an increase in I-beta-D-arabinofuranosyluracil (ara-U) formation, a decrease in ara-C 5'-triphosphate (ara-CTP) accumulation, and a rise in cell viability with increasing cell number. These findings indicate that unlike ara-C, the effectiveness of 3'-NH2-dCyd is independent of the level of deaminase, which suggests its possible utility in situations in which high levels of deaminase are manifest.

journal_name

Cancer Chemother Pharmacol

journal_title

Cancer chemotherapy and pharmacology

authors

Mancini WR

doi

10.1007/BF00686406

keywords:

subject

Has Abstract

pub_date

1992-01-01 00:00:00

pages

139-44

issue

eissn

0344-5704

issn

1432-0843

journal_volume

pub_type

杂志文章

在线工具

The role of deoxycytidine-metabolizing enzymes in the cytotoxicity induced by 3'-amino-2',3'-dideoxycytidine and cytosine arabinoside.