Koistinen P, Wang C, Curtis J E, McCulloch E A
Department of Internal Medicine, University of Oulu, Finland.
Leukemia. 1991 Sep;5(9):789-95.
The blast cells of acute myeloblastic leukemia (AML) usually require growth factors for optimum proliferation in cell culture. Growth factors also affect the sensitivity of AML blast cells to cytosine arabinoside (ara-C). Others have reported that factor-treated cells are more ara-C sensitive than blasts in culture without factors. These authors have reported previously that AML blasts grown with rG-CSF, with or without GM-CSF, are more sensitive than cells in GM-CSF alone. This paper reports experiments which show that changes in the ara-C sensitivities of blast cells in different growth factors are not explained by changes in the percentage of cells in the DNA synthesis (S) phase of the cycle. Blasts freshly obtained from five AML patients were cultured in either rG-CSF, rGM-CSF, or rIL-3; they were then exposed to 20 min pulses of either high specific activity tritiated thymidine (3HTdR) or a high concentration of ara-C. Regardless of the factor present, the pulse of 3HTdR decreased the number of clonogenic cells by about 50%, the result expected for actively proliferating cells with an S phase occupying about half the cycle time. The same result was found for four of the five blast cell populations grown in G-CSF and pulsed with ara-C; in contrast, clonogenic cells grown in GM-CSF or IL-3 from these four populations were not killed by ara-C. The blasts from the fifth patient were ara-C resistant under all conditions. It was concluded that exposure to GM-CSF or IL-3 decreased ara-C sensitivity in blasts that were actively making DNA. The observation was explored in more detail using a cell line (OCI/AML-1a) that is both ara-C sensitive and growth factor dependent. These studies showed that about 15 h of growth in factor are required for a change in ara-C sensitivity.
急性髓细胞白血病（AML）的原始细胞通常需要生长因子才能在细胞培养中实现最佳增殖。生长因子也会影响AML原始细胞对阿糖胞苷（ara-C）的敏感性。其他人曾报道，经因子处理的细胞比未添加因子培养的原始细胞对ara-C更敏感。这些作者之前曾报道，在有或没有GM-CSF的情况下，用rG-CSF培养的AML原始细胞比仅用GM-CSF培养的细胞更敏感。本文报道的实验表明，不同生长因子条件下原始细胞对ara-C敏感性的变化无法用细胞周期中DNA合成（S）期细胞百分比的变化来解释。从5例AML患者新鲜获取的原始细胞分别在rG-CSF、rGM-CSF或rIL-3中培养；然后将它们暴露于高比活度氚标记胸腺嘧啶核苷（3HTdR）或高浓度ara-C的20分钟脉冲中。无论存在何种因子，3HTdR脉冲使克隆形成细胞数量减少约50%，这是处于S期占细胞周期约一半时间的活跃增殖细胞所预期的结果。在G-CSF中培养并用ara-C脉冲处理的5个原始细胞群体中有4个得到了相同结果；相比之下，这4个群体中在GM-CSF或IL-3中培养的克隆形成细胞未被ara-C杀死。第5例患者的原始细胞在所有条件下均对ara-C耐药。得出的结论是，暴露于GM-CSF或IL-3会降低正在进行DNA合成的原始细胞对ara-C的敏感性。使用既对ara-C敏感又依赖生长因子的细胞系（OCI/AML-1a）对这一观察结果进行了更详细的探究。这些研究表明，需要约15小时的因子培养时间才能使ara-C敏感性发生变化。
