INSERM U872, Université Pierre et Marie Curie, Université Paris Descartes, Centre de Recherche des Cordeliers, Paris, France.
PLoS One. 2011;6(10):e25963. doi: 10.1371/journal.pone.0025963. Epub 2011 Oct 6.
The natural phloroglucinol hyperforin HF displays anti-inflammatory and anti-tumoral properties of potential pharmacological interest. Acute myeloid leukemia (AML) cells abnormally proliferate and escape apoptosis. Herein, the effects and mechanisms of purified HF on AML cell dysfunction were investigated in AML cell lines defining distinct AML subfamilies and primary AML cells cultured ex vivo.
HF inhibited in a time- and concentration-dependent manner the growth of AML cell lines (U937, OCI-AML3, NB4, HL-60) by inducing apoptosis as evidenced by accumulation of sub-G1 population, phosphatidylserine externalization and DNA fragmentation. HF also induced apoptosis in primary AML blasts, whereas normal blood cells were not affected. The apoptotic process in U937 cells was accompanied by downregulation of anti-apoptotic Bcl-2, upregulation of pro-apoptotic Noxa, mitochondrial membrane depolarization, activation of procaspases and cleavage of the caspase substrate PARP-1. The general caspase inhibitor Z-VAD-fmk and the caspase-9- and -3-specific inhibitors, but not caspase-8 inhibitor, significantly attenuated apoptosis. HF-mediated apoptosis was associated with dephosphorylation of active Akt1 (at Ser(473)) and Akt1 substrate Bad (at Ser(136)) which activates Bad pro-apoptotic function. HF supppressed the kinase activity of Akt1, and combined treatment with the allosteric Akt1 inhibitor Akt-I-VIII significantly enhanced apoptosis of U937 cells.
Our data provide new evidence that HF's pro-apoptotic effect in AML cells involved inhibition of Akt1 signaling, mitochondria and Bcl-2 members dysfunctions, and activation of procaspases -9/-3. Combined interruption of mitochondrial and Akt1 pathways by HF may have implications for AML treatment.
天然间苯三酚衍生物高异黄酮 HF 具有抗炎和抗肿瘤特性，具有潜在的药理意义。急性髓系白血病 (AML) 细胞异常增殖并逃避凋亡。本研究旨在探讨纯化的 HF 对 AML 细胞系和体外培养的原代 AML 细胞功能障碍的影响及其机制。
HF 以时间和浓度依赖的方式抑制 AML 细胞系（U937、OCI-AML3、NB4、HL-60）的生长，通过诱导细胞凋亡来证明，细胞凋亡表型为亚 G1 期细胞群积累、磷脂酰丝氨酸外翻和 DNA 片段化。HF 还诱导原代 AML 母细胞凋亡，而正常血细胞不受影响。U937 细胞中的凋亡过程伴随着抗凋亡 Bcl-2 的下调，促凋亡 Noxa 的上调，线粒体膜去极化，procaspase 的激活和 caspase 底物 PARP-1 的裂解。通用 caspase 抑制剂 Z-VAD-fmk 和 caspase-9 和 -3 特异性抑制剂，但不是 caspase-8 抑制剂，显著减弱了细胞凋亡。HF 介导的凋亡与 Akt1（在 Ser(473)）和 Akt1 底物 Bad（在 Ser(136)）的活性磷酸化失活有关，后者激活 Bad 的促凋亡功能。HF 抑制 Akt1 的激酶活性，与变构 Akt1 抑制剂 Akt-I-VIII 联合处理可显著增强 U937 细胞的凋亡。
我们的数据提供了新的证据，表明 HF 在 AML 细胞中的促凋亡作用涉及 Akt1 信号通路、线粒体和 Bcl-2 家族功能障碍以及 procaspase-9/-3 的激活。HF 对线粒体和 Akt1 途径的联合阻断可能对 AML 的治疗具有重要意义。
