Flavopiridol downregulates the expression of both the inducible NO synthase and p27kip1 in malignant cells from B-cell chronic lymphocytic leukemia
Flavopiridol downregulates the expression of both the inducible NO synthase and p27kip1 in malignant cells from B-cell chronic lymphocytic leukemia
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DOI：
10.1038/sj.leu.2403139
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发表时间：
2003-12-01
期刊：
影响因子：
11.4
通讯作者：
Kolb, JP
中科院分区：
文献类型：
--
作者：
Billard, C;Kern, C;Kolb, JP
Flavopiridol是细胞周期蛋白依赖性激酶和其他蛋白激酶的抑制剂，在体外诱导B细胞慢性淋巴细胞白血病（B-CLL）恶性细胞凋亡。以前，我们报道了一氧化氮（NO），诱导型一氧化氮合酶（iNOS），自发表达的B-CLL细胞产生的，有助于他们的缺陷，在凋亡。在目前的工作中，我们表明，从B-CLL患者的白血病细胞与flavopiridol离体治疗的结果在抑制iNOS的表达，通过免疫荧光和蛋白质印迹法测定，并在一个显着的抑制NO的生产原位测量与特定的荧光探针（FLAP-2 DA）。这些作用伴随着细胞凋亡的膜、线粒体和核事件。Flavopiridol暴露还导致半胱天冬酶3活性的刺激和p27（kip 1）的半胱天冬酶依赖性裂解，p27是细胞周期的负调节剂，其在B-CLL中过表达。因此，flavopiridol能够下调B-CLL细胞中的iNOS和p27（kip 1）表达。此外，flavopiridol促进的细胞凋亡是部分逆转的NO供体，这表明NO通路的抑制可能参与flavopiridol对白血病细胞的凋亡作用。
Flavopiridol, an inhibitor of cyclin-dependent kinases and other protein kinases, induces in vitro apoptosis of malignant cells from B-cell chronic lymphocytic leukemia (B-CLL). Previously, we reported that nitric oxide ( NO), produced by an inducible NO synthase ( iNOS), spontaneously expressed by the B-CLL cells, contributed to their deficiency in apoptosis. In the present work, we show that ex vivo treatment of leukemic cells from B-CLL patients with flavopiridol results in the inhibition of iNOS expression, as determined by immunofluorescence and Western blotting, and in a marked inhibition of NO production measured in situ with a specific fluorescent probe (DAF-2 DA). These effects are accompanied by membrane, mitochondrial and nuclear events of apoptosis. Flavopiridol exposure also results in the stimulation of caspase 3 activity and in caspase-dependent cleavage of p27(kip1), a negative regulator of the cell cycle, which is overexpressed in B-CLL. Thus, flavopiridol is capable of downregulating both iNOS and p27(kip1) expression in B-CLL cells. Furthermore, flavopiridol-promoted apoptosis is partly reverted by an NO donor, suggesting that inhibition of the NO pathway could participate in the apoptotic effects of flavopiridol on the leukemic cells.