The method to surmise the prognosis of leukemia patients by analyzing the function of Notch protein

Notch信号调节造血祖细胞的自我更新和分化。由于急性髓细胞白血病（AML）起源于造血祖细胞的异常生长，Notch系统可能参与了异常生长。我们先前报道AML细胞表达Notch蛋白。在这项研究中，我们研究了Notch配体对原代AML细胞生长和分化的影响。在用配体或对照IgG包被的威尔斯孔中培养AML细胞。评价其短期生长、自我更新能力和分化能力。配体刺激在短期生长中引起三种类型的反应，即促进、抑制或无显著影响。自我更新能力被抑制或不受配体的显着影响。配体刺激改变了一些样本中的原始细胞为巨噬细胞样细胞。因此，由配体刺激引起的Notch活化具有不同的效果。细胞反应性与患者预后的关系尚不清楚。本研究探讨Notch激活对维甲酸（RA）诱导的分化和凋亡的影响。急性早幼粒细胞白血病（APL）细胞在RA的作用下发生嗜酸性分化和凋亡。Notch配体诱导的Notch活化使RA处理的部分NB 4细胞呈单核样形态，减少凋亡。Notch配体抑制RA诱导的caspase-8和PARP的裂解，这可能是其抑制RA诱导的细胞凋亡的机制之一。在某些细胞中，药物诱导的生长抑制被配体刺激轻微降低。配体包被的培养板比普通培养板更接近人骨髓中的微环境。我们将进一步研究使用配体包被板进行药物敏感性试验的临床实用性。

Notch signaling regulates the self-renewal and differentiation of hematopoietic progenitors. Since acute myeloblastic leukemia (AML) originates from dysregulated hematopoietic progenitors, the Notch system may be involved in the abnormal growth. We previously reported that AML cells express Notch proteins. In this study, we examined the effects of Notch ligands on the growth and differentiation of primary AML cells. AML cells were cultured in wells coated with the ligands or control IgG. The short-term growth, self-renewal capacity and differentiation were evaluated. The ligand stimulation caused three types of response in the short-term growth, namely, promotion, suppression or no significant effect. The self-renewal capacity was suppressed or not significantly affected by the ligands. The ligand stimulation altered blast cells into macrophage-like cells in some samples. Thus, Notch activation caused by the ligand stimulation had diverse effects. The relationship between responsiveness of the cells and prognosis of the patients could not be clarified yet.Effects of Notch activation on retinoic acid (RA)-induced differentiation and apoptosis were investigated. Acute promyelocytic leukemia (APL) cells undergo neutrophilic differentiation and apoptosis by RA. Notch activation induced by the Notch ligands made part of RA-treated NB4 cells monocyte-like shaped and reduced the apoptosis. The ligands suppressed the RA-induced cleavage of caspase-8 and PARP, which may be a possible mechanism through which the ligands suppress the RA-induced apoptosis.The effect of the Notch ligands on drug-sensitivity of leukemia cells was examined. The drug-induced growth suppression was slightly reduced by the ligand stimulation in some cells. The ligand-coated culture-plates are more similar to the microenvironment in human bone marrow than ordinary plates. We will further examine the clinical usefulness of the drug-sensitivity test using the ligand-coated plates.