Funato K, Miyazawa K, Yaguchi M, Gotoh A, Ohyashiki K
First Department of Internal Medicine (Hematology/Oncology), Tokyo Medical University, Tokyo, Japan.
Leukemia. 2002 Aug;16(8):1519-27. doi: 10.1038/sj.leu.2402614.
We originally reported that vitamin K(2) (VK2) effectively induces apoptosis in various types of primary cultured leukemia cells and leukemia cell lines in vitro. In addition, VK2 was shown to induce differentiation of leukemia cells when the cells were resistant against VK2-inducing apoptosis. A novel synthetic vitamin D(3)derivative, 22-oxa-1,25-dihydroxyvitamin D(3) (OCT: oxacarcitriol) shows a more potent differentiation-inducing ability among myeloid leukemia cells in vitro with much lesser extent of the induction of hypercalcemia in vivo as compared to the effects of 1alpha,25(OH)(2)D(3). In the present study, we focused on the effects of a combination of OCT plus VK2 on leukemia cells. Treatment of HL-60 cells with OCT for 72 h induces monocytic differentiation. A combination of OCT plus VK2 dramatically enhances monocytic differentiation as assessed by morphologic features, positivity for non-specific esterase staining, and cell surface antigen expressions. This combined effect far exceeds the maximum differentiation induction ability at the optimal concentrations of either OCT or VK2 alone. In addition, pronounced accumulation of the cells in the G0/G1 phase is observed by combined treatment with OCT plus VK2 as compared with each vitamin alone. In contrast to cell differentiation, caspase-3 activation and apoptosis induction in response to VK2 are significantly suppressed in the presence of OCT in HL-60 cells. These data suggest that monocytic differentiation and apoptosis induction of HL-60 cells are inversely regulated. Furthermore, pronounced induction of differentiation by combined treatment with VK2 plus OCT was also observed in four out of six cases of primary cultured acute myeloid leukemia cells in vitro, suggesting that VK2 plus OCT might be a potent combination for the differentiation-based therapy for acute myeloid leukemias.
我们最初报道维生素K(2)（VK2）在体外可有效诱导多种原代培养的白血病细胞和白血病细胞系发生凋亡。此外，当白血病细胞对VK2诱导的凋亡产生抗性时，VK2可诱导白血病细胞分化。一种新型合成维生素D(3)衍生物，22-氧杂-1,25-二羟基维生素D(3)（OCT：奥沙骨化醇）在体外对髓系白血病细胞显示出更强的诱导分化能力，与1α,25(OH)(2)D(3)相比，其在体内诱导高钙血症的程度要小得多。在本研究中，我们重点关注OCT加VK2联合用药对白血病细胞的影响。用OCT处理HL-60细胞72小时可诱导单核细胞分化。通过形态学特征、非特异性酯酶染色阳性以及细胞表面抗原表达评估，OCT加VK2联合用药可显著增强单核细胞分化。这种联合效应远远超过单独使用OCT或VK2最佳浓度时的最大分化诱导能力。此外，与单独使用每种维生素相比，OCT加VK2联合处理可使细胞在G0/G1期明显积累。与细胞分化相反，在HL-60细胞中存在OCT时，VK2诱导的半胱天冬酶-3激活和凋亡诱导受到显著抑制。这些数据表明HL-60细胞的单核细胞分化和凋亡诱导呈反向调节。此外，在体外原代培养的6例急性髓系白血病细胞中有4例也观察到VK2加OCT联合处理可显著诱导分化，这表明VK2加OCT可能是急性髓系白血病基于分化疗法的有效联合用药。
