Bierau Jörgen, Van Gennip Albert H, Leen René, Helleman Jozien, Caron Huib N, Van Kuilenburg André B P
Department of Clinical Chemistry, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, the Netherlands.
Int J Cancer. 2003 Jan 20;103(3):387-92. doi: 10.1002/ijc.10858.
CPEC is a potent inhibitor of CTP synthetase and causes depletion of CTP and dCTP pools. AraC is an analog of dCyd and a chemotherapeutic agent. Here, we demonstrate that, upon incubation with CPEC, both the anabolism and cytostatic effect of AraC in SK-N-BE(2)c neuroblastoma cells were increased. Cotreatment of CPEC (50-250 nM) and AraC (37.5-500 nM) decreased the 4-day ED(50) value for AraC 2- to 8-fold in the SK-N-BE(2)c cell line, while pretreatment with CPEC followed by incubation with AraC alone decreased the 4-day ED(50) value for AraC 1- to 19-fold. Preincubation of SK-N-BE(2)c cells with 100 nM CPEC followed by incubation with 500 nM [(3)H]AraC increased the total amount of AraC nucleotides and incorporation of [(3)H]AraC into DNA by 392% and 337%, respectively, compared to non-CPEC-treated cells. When 20 nM [(3)H]AraC was used, the maximum incorporation of [(3)H]AraC into DNA was 1,378% compared to non-CPEC-treated cells. Incorporation of AraC into DNA correlated well with the accumulation of cells in S phase of the cell cycle caused by CPEC. DNA synthesis was almost completely inhibited (>91%) when 100 nM CPEC and 500 nM AraC were combined. CPEC alone and the combination of CPEC and AraC increased caspase-3 activity 3-fold, indicating induction of apoptosis in SK-N-BE(2)c cells. In contrast, AraC alone did not induce caspase-3 activity. Our results demonstrate that low concentrations of CPEC profoundly increase the cytostatic properties of AraC toward SK-N-BE(2)c human neuroblastoma cells.
CPEC是胞苷三磷酸合成酶的有效抑制剂，可导致CTP和dCTP池耗竭。阿糖胞苷（AraC）是脱氧胞苷（dCyd）的类似物，也是一种化疗药物。在此，我们证明，在与CPEC孵育后，AraC在SK-N-BE(2)c神经母细胞瘤细胞中的合成代谢和细胞生长抑制作用均增强。CPEC（50 - 250 nM）与AraC（37.5 - 500 nM）联合处理使SK-N-BE(2)c细胞系中AraC的4天半数有效剂量（ED50）值降低了2至8倍，而先用CPEC预处理再单独与AraC孵育使AraC的4天ED50值降低了1至19倍。用100 nM CPEC预孵育SK-N-BE(2)c细胞，然后与500 nM [³H]AraC孵育，与未用CPEC处理的细胞相比，AraC核苷酸的总量以及[³H]AraC掺入DNA的量分别增加了392%和337%。当使用20 nM [³H]AraC时，与未用CPEC处理的细胞相比，[³H]AraC掺入DNA的最大量增加了1378%。AraC掺入DNA与CPEC引起的细胞周期S期细胞积累密切相关。当100 nM CPEC与500 nM AraC联合使用时，DNA合成几乎完全被抑制（>91%）。单独使用CPEC以及CPEC与AraC联合使用均可使半胱天冬酶-3活性增加3倍，表明在SK-N-BE(2)c细胞中诱导了细胞凋亡。相比之下，单独使用AraC不会诱导半胱天冬酶-3活性。我们的结果表明，低浓度的CPEC可显著增强AraC对SK-N-BE(2)c人神经母细胞瘤细胞的细胞生长抑制特性。
