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。由于急性髓系白血病(AML)起源于异常的造血祖细胞，Notch系统可能参与了AML的异常生长。我们以前报道过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。将AML细胞接种于包被配体或对照免疫球蛋白的孔中。对细胞的短期生长、自我更新能力和分化能力进行评价。在短期生长中，配体刺激引起了三种类型的反应，即促进、抑制或没有显著作用。配体对细胞的自我更新能力有抑制作用或无明显影响。在某些样本中，配体刺激将原始细胞转化为巨噬细胞样细胞。因此，配体刺激引起的Notch激活具有不同的效应。Notch激活对维甲酸(RA)诱导分化和细胞凋亡的影响。急性早幼粒细胞白血病(APL)细胞通过类风湿因子(RA)诱导中性粒细胞分化和凋亡。Notch配体诱导的Notch激活使RA处理的NB4细胞部分呈单核细胞样变，减少了细胞的凋亡率。抑制RA诱导的caspase-8和PARP的裂解，这可能是其抑制RA诱导的细胞凋亡的可能机制。在某些细胞中，药物诱导的生长抑制作用被配体刺激略有减轻。与普通培养板相比，配体包被的培养板更接近人骨髓微环境。我们将进一步检查使用配基涂层平板进行药敏试验的临床实用性。

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.