Okabe Seiichi, Tauchi Tetsuzo, Nakajima Akihiro, Sashida Goro, Gotoh Akihiko, Broxmeyer Hal E, Ohyashiki Junko H, Ohyashiki Kazuma
First Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan.
Stem Cells Dev. 2007 Jun;16(3):503-14. doi: 10.1089/scd.2007.9994.
Resistance to imatinib can occur in patients with chronic myelogenous leukemia (CML). In this study, we report mechanisms of action of histone deacetylase (HDAC) inhibitor, depsipeptide (FK228) in BCR/ABL-expressing cell lines and its effectiveness in imatinib-resistant cells from patients with blast crisis of CML. FK228 potently induced apoptosis of TF-1 BCR/ABL, K562, and H7 BCR/ABL cells. We found that histone H4, BCR/ABL, heat shock protein 90 (HSP-90), p53, focal adhesion kinase (FAK), paxillin, and retinoblastoma protein (Rb) were acetylated in the treated cells. Cells were also blocked in G(2)/M phase of the cell cycle and activity of mitogen-activated protein kinase (MAPK) was blocked, but p38MAPK (p38) was activated. Inhibitor of apoptosis proteins (IAPs) were suppressed, and common results of apoptotic induction were observed, such as caspase-3, caspase-9, and poly(ADP-ribose) polymerase (PARP) activation. Although p38 was phosphorylated after FK228 treatment, histone H4 acetylation, caspase-3 activation, and apoptosis were not inhibited by treatment with the p38 inhibitor SB203580. We also found that human telomerase reverse transcriptase (hTERT) ShRNA-transfected cells demonstrated decreased FK228-induced apoptosis. Of clinical relevance, FK228-induced apoptosis of imatinib-resistant primary cells from patients with CML, who had progressed to blast crisis (BC) while receiving therapy with imatinib. In conclusion, FK228 potently induces apoptosis of CML cells by acetylation and degradation of BCR/ABL protein. Our study suggests how FK228 may mediate its effects on imatinib-resistant CML cells.
慢性粒细胞白血病（CML）患者可能会出现对伊马替尼的耐药性。在本研究中，我们报告了组蛋白去乙酰化酶（HDAC）抑制剂缩肽（FK228）在表达BCR/ABL的细胞系中的作用机制及其对CML急变期患者伊马替尼耐药细胞的有效性。FK228能有效诱导TF-1 BCR/ABL、K562和H7 BCR/ABL细胞凋亡。我们发现，在经处理的细胞中，组蛋白H4、BCR/ABL、热休克蛋白90（HSP-90）、p53、粘着斑激酶（FAK）、桩蛋白和视网膜母细胞瘤蛋白（Rb）发生了乙酰化。细胞在细胞周期的G(2)/M期也被阻滞，丝裂原活化蛋白激酶（MAPK）的活性被阻断，但p38 MAPK（p38）被激活。凋亡抑制蛋白（IAPs）受到抑制，并观察到凋亡诱导的常见结果，如半胱天冬酶-3、半胱天冬酶-9和聚（ADP-核糖）聚合酶（PARP）的激活。虽然FK228处理后p38发生了磷酸化，但组蛋白H4乙酰化、半胱天冬酶-3激活和凋亡并未被p38抑制剂SB203580抑制。我们还发现，转染人端粒酶逆转录酶（hTERT）短发夹RNA（ShRNA）的细胞显示FK228诱导的凋亡减少。具有临床相关性的是，FK228可诱导CML患者伊马替尼耐药原代细胞凋亡，这些患者在接受伊马替尼治疗时已进展至急变期（BC）。总之，FK228通过使BCR/ABL蛋白乙酰化和降解有效诱导CML细胞凋亡。我们的研究表明了FK228可能如何介导其对伊马替尼耐药CML细胞的作用。
