Johnston J B, Daeninck P, Verburg L, Lee K, Williams G, Israels L G, Mowat M R, Begleiter A
Manitoba Institute of Cell Biology, Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
Leuk Lymphoma. 1997 Aug;26(5-6):435-49. doi: 10.3109/10428199709050881.
Most antitumor agents exert their cytotoxic effect through the induction of apoptosis, and this process may be mediated through an elevation in p53 protein, with a subsequent increase in bax and decrease in bcl-2. p53 also increases mdm-2 expression and mdm-2 may then bind and inactivate p53. Cells from 31 patients with chronic lymphocytic leukemia (CLL) were treated in vitro with 2-chlorodeoxyadenosine (CdA), arabinosyl-2-fluoroadenine (F-ara-A), or chlorambucil (CLB) and drug sensitivity measured using the MTT assay. The protein levels of bax and bcl-2 were measured in CLL cells from 25 patients, and were found to be higher in leukemic cells than in normal B cells. The bcl-2 levels varied three-fold, the bax levels fifteen-fold, and the bax:bcl-2 ratios ranged from 0.44 to 2.91. The expression of mdm-2 mRNA was measured in CLL cells from 28 patients and was found to vary twenty-fold. However, no correlation was observed between drug sensitivity to CdA, F-ara-A, or CLB and the cellular levels of mdm-2 mRNA, or the protein levels of bax or bcl-2, or the bax:bcl-2 ratio. Treatment of CLL cells having wild type p53 with CdA, F-ara-A or CLB produced an increase in p53 protein and mdm-2 mRNA. This was not observed in cells having a p53 mutation, and these cells were highly resistant to both CLB and the nucleoside analogs. In contrast to the nucleoside analogs and CLB, dexamethasone and vincristine had no effect on mdm-2 mRNA levels. Treatment of CLL cells containing a wild type p53 gene with CdA, F-ara-A, or CLB, did not produce any consistent changes in bax or bcl-2. Thus, CdA, F-ara-A and CLB appear to act in CLL cells through a p53-dependent pathway, whereas this does not occur with dexamethasone or vincristine. The cellular levels of mdm-2, bcl-2, bax or the bax:bcl-2 ratios are not predictive indicators of clinical sensitivity in CLL, but an increase in mdm-2 levels after drug treatment is indicative of p53 function in these cells.
大多数抗肿瘤药物通过诱导细胞凋亡发挥其细胞毒性作用，这一过程可能通过p53蛋白水平升高介导，随后bax增加而bcl-2减少。p53还会增加mdm-2的表达，然后mdm-2可能结合并使p53失活。对31例慢性淋巴细胞白血病（CLL）患者的细胞进行体外培养，分别用2-氯脱氧腺苷（CdA）、阿糖基-2-氟腺嘌呤（F-ara-A）或苯丁酸氮芥（CLB）处理，并用MTT法测定药物敏感性。检测了25例CLL患者细胞中bax和bcl-2的蛋白水平，发现白血病细胞中的水平高于正常B细胞。bcl-2水平变化了3倍，bax水平变化了15倍，bax:bcl-2比值在0.44至2.91之间。检测了28例CLL患者细胞中mdm-2 mRNA的表达，发现其变化了20倍。然而，未观察到对CdA、F-ara-A或CLB的药物敏感性与mdm-2 mRNA的细胞水平、bax或bcl-2的蛋白水平或bax:bcl-2比值之间存在相关性。用CdA、F-ara-A或CLB处理具有野生型p53的CLL细胞后，p53蛋白和mdm-2 mRNA增加。在具有p53突变的细胞中未观察到这种情况，并且这些细胞对CLB和核苷类似物均高度耐药。与核苷类似物和CLB不同，地塞米松和长春新碱对mdm-2 mRNA水平没有影响。用CdA、F-ara-A或CLB处理含有野生型p53基因的CLL细胞后，bax或bcl-2没有产生任何一致的变化。因此，CdA、F-ara-A和CLB似乎通过p53依赖性途径在CLL细胞中起作用，而地塞米松或长春新碱则不然。mdm-2、bcl-2、bax的细胞水平或bax:bcl-2比值不是CLL临床敏感性的预测指标，但药物治疗后mdm-2水平的增加表明这些细胞中p53的功能。
