Issaad C, Vainchenker W
INSERM U 362, Institut Gustave Roussy, Villejuif, France.
Blood. 1994 Nov 15;84(10):3447-56.
The mechanisms of the chronic myeloid leukemia (CML) clones proliferative advantage over normal clones are currently unknown. They may involve an insensitivity to a negative regulation of a growth factor-independent proliferation. Clonogenic progenitors from CML patient blood or marrow in chronic phase were grown either in the presence or absence of recombinant growth factors. No erythroid colonies were observed in the absence of any cytokine. In contrast, erythroid colonies composed of fully mature hemoglobinized erythroblasts (day 12 burst-forming units-erythroid) were obtained in the presence of Steel factor (SF) alone. Addition of erythropoietin (Epo) to SF either had no effect on the cloning efficiency or increased up to 50% the number of erythroid colonies. No erythroid growth was observed when cultures were stimulated by interleukin-3 or granulocyte-macrophage colony-stimulating factor alone. Similar erythroid growth in the presence of SF but without Epo was obtained in "serum-free" cultures when purified blood CML CD34+ cells were grown. This growth of erythroid colonies in the absence of Epo was not accounted for by an autocrine stimulation loop by Epo, because neutralizing antibodies against Epo did not inhibit it. This abnormal response to growth factor was specifically observed in the CML clone, as shown by the presence of the BCR-ABL transcript in all of these erythroid colonies. The direct implication of BCR-ABL was further documented (1) by studies of alpha-interferon-treated patients with a chimerism in which the abnormal growth correlates with the presence of the malignant clone and (2) by the use of antisense oligonucleotide against BCR-ABL transcript, which abrogated this abnormal growth. Finally, erythroid growth in the SF presence was greatly diminished by herbimycin A, whereas, at the same concentration, this tyrosine kinase inhibitor had no marked effect on erythroid colony formation in the presence of SF plus Epo on CML or normal marrow cells. This result suggests that the BCR-ABL kinase activity leads directly to this Epo-independent terminal differentiation requiring, however, the presence of SF.
慢性髓性白血病（CML）克隆相对于正常克隆的增殖优势机制目前尚不清楚。它们可能涉及对生长因子非依赖性增殖的负调控不敏感。慢性期CML患者血液或骨髓中的克隆形成祖细胞在有或无重组生长因子的情况下生长。在没有任何细胞因子的情况下未观察到红系集落。相反，仅在存在Steel因子（SF）的情况下获得了由完全成熟的血红蛋白化成红细胞（第12天爆式红系集落形成单位）组成的红系集落。向SF中添加促红细胞生成素（Epo）对克隆效率要么没有影响，要么使红系集落数量增加多达50%。当单独用白细胞介素-3或粒细胞-巨噬细胞集落刺激因子刺激培养物时，未观察到红系生长。当纯化的血液CML CD34+细胞生长时，在“无血清”培养物中，在存在SF但没有Epo的情况下获得了类似的红系生长。在没有Epo的情况下红系集落的这种生长不是由Epo的自分泌刺激环引起的，因为针对Epo的中和抗体并不能抑制它。如所有这些红系集落中存在BCR-ABL转录本所示，这种对生长因子的异常反应在CML克隆中特异性观察到。BCR-ABL的直接影响通过以下研究进一步得到证实：（1）对α-干扰素治疗的具有嵌合现象的患者的研究，其中异常生长与恶性克隆的存在相关；（2）使用针对BCR-ABL转录本的反义寡核苷酸，其消除了这种异常生长。最后，在存在SF的情况下，除草霉素A可大大减少红系生长，而在相同浓度下，这种酪氨酸激酶抑制剂对存在SF加Epo的CML或正常骨髓细胞中的红系集落形成没有明显影响。该结果表明BCR-ABL激酶活性直接导致这种不依赖Epo的终末分化，然而，这需要存在SF。
