Bergman A M, Pinedo H M, Jongsma A P, Brouwer M, Ruiz van Haperen V W, Veerman G, Leyva A, Eriksson S, Peters G J
Department of Oncology, University Hospital VU, Amsterdam, The Netherlands.
Biochem Pharmacol. 1999 Feb 15;57(4):397-406. doi: 10.1016/s0006-2952(98)00318-9.
We determined the potential activity of 2',2'-difluorodeoxycytidine (gemcitabine, dFdC) in 1-beta-D-arabinofuranosylcytidine (ara-C)-sensitive and-resistant leukemia cell lines. Both drugs are phosphorylated by deoxycytidine kinase (dCK); the triphosphates, dFdCTP and ara-CTP, respectively, are incorporated into DNA. In the murine leukemia cell line L1210, induction of resistance to ara-C resulted in the 2200-fold resistant subline L4A6. The Brown Norway rat myelocytic leukemia ara-C-sensitive cell line (BCLO) was >300-fold more sensitive to ara-C than its variant Bara-C. In L1210 cells, gemcitabine was 8-fold more active than ara-C; in L4A6, BCLO, and Bara-C cells, gemcitabine was 16-, 28-, and more than 3-fold more active than ara-C, respectively. A partial explanation for these differences may be the higher dCK activity in the parental cell lines L1210 and BCLO with gemcitabine compared to ara-C as a substrate. DCK activity was not or hardly detectable in the resistant L4A6 and Bara-C cell. In the rat leukemia cell lines, deoxycytidine (dCyd) phosphorylation activity showed an aberrant pattern, since the activity with dCyd was 1.5-fold higher in the Bara-C cell line compared with BCLO, possibly due to thymidine kinase 2. The wild-type L1210 cells accumulated at least 3-fold more ara-CTP and dFdCTP than the rat leukemia cell line BCLO. The ara-C-resistant variants L4A6 and Bara-C did not accumulate dFdCTP or ara-CTP. In conclusion, gemcitabine was more active than ara-C in all leukemia cell lines tested. The sensitivity of the wild-type cell lines correlates with the accumulation of dFdCTP and ara-CTP, but is independent of dCK. However, both resistant variants had decreased dCK activities, but were relatively more sensitive to dFdC than to ara-C.
我们测定了2',2'-二氟脱氧胞苷（吉西他滨，dFdC）在对1-β-D-阿拉伯呋喃糖基胞嘧啶（阿糖胞苷，ara-C）敏感和耐药的白血病细胞系中的潜在活性。两种药物均由脱氧胞苷激酶（dCK）磷酸化；三磷酸产物，即dFdCTP和ara-CTP，分别掺入DNA中。在小鼠白血病细胞系L1210中，对阿糖胞苷耐药的诱导产生了2200倍耐药的亚系L4A6。棕色挪威大鼠骨髓性白血病阿糖胞苷敏感细胞系（BCLO）对阿糖胞苷的敏感性比其变体Bara-C高300倍以上。在L1210细胞中，吉西他滨的活性比阿糖胞苷高8倍；在L4A6、BCLO和Bara-C细胞中，吉西他滨的活性分别比阿糖胞苷高16倍、28倍和3倍以上。这些差异的部分解释可能是与以阿糖胞苷作为底物相比，亲本细胞系L1210和BCLO中以吉西他滨作为底物时具有更高的dCK活性。在耐药的L4A6和Bara-C细胞中未检测到或几乎检测不到DCK活性。在大鼠白血病细胞系中，脱氧胞苷（dCyd）磷酸化活性呈现异常模式，因为与BCLO相比，Bara-C细胞系中dCyd的活性高1.5倍，这可能归因于胸苷激酶2。野生型L1210细胞积累的ara-CTP和dFdCTP至少比大鼠白血病细胞系BCLO多3倍。阿糖胞苷耐药变体L4A6和Bara-C不积累dFdCTP或ara-CTP。总之，在所有测试的白血病细胞系中，吉西他滨的活性均高于阿糖胞苷。野生型细胞系的敏感性与dFdCTP和ara-CTP的积累相关，但与dCK无关。然而，两种耐药变体的dCK活性均降低，但对dFdC的敏感性相对高于对阿糖胞苷的敏感性。
