慢性髓系白血病STI571耐药与Bcr-Abl基因点突变的关系

目的通过Bcr-Abl激酶ATP结合区测序分析,探讨慢性髓系白血病(CML)STI571耐药与Bcr-Abl基因点突变的关系。方法将CML患者分为对STI571耐药和非耐药两组,细胞系分为STI571耐药细胞系K562/G01、野生型K562/W细胞,进行骨髓单个核细胞或细胞系细胞Abl基因ATP结合区双向测序分析,了解Abl酪氨酸激酶ATP结合区点突变情况。PCR产物的序列长度为344bp,其中的180bp(98～277bp)为ABL激酶的第906～1085bpDNA序列片段,涵盖了Abl激酶的ATP结合区序列。结果K562/G01耐药细胞ABL激酶ATP结合区DNA测序与K562/W相同,与ABL激酶原序列相比,有两个同义点突变。在STI571耐药急变的CML患者骨髓单个核细胞Abl激酶ATP结合区测序结果发现:在8例耐药急变的患者中2例患者第944位核苷酸C→T单个碱基出现点突变,使苏氨酸(Thr)突变为异亮氨酸(Ile)。1例CML-CP的患者第1070碱基A→G替换,导致357位赖氨酸(Lys)→精氨酸(Arg)。结论Bcr/Abl融合基因ATP结合区的点突变是CML中STI571耐药的重要原因之一,对指导临床用药具有重要价值。     

BCR-ABL酪氨酸激酶抑制剂STI571选择性诱导K562细胞凋亡

目的 探讨STI571抑制慢性髓性白血病（CML）细胞株增殖的机理及特异性。方法 选用非特异性的凋亡诱导剂阿霉素和BCR－ABL阴性的白血病细胞株MO7E作为对照，观察两种抑制剂作用下两种细胞形态学的改变和胞浆DNA电泳图的改变。结果 STI571可诱导K562细胞凋亡，而对MO7E细胞无致凋亡作用；阿霉素可诱导MO7E细胞凋亡，而对K562细胞无诱导凋亡作用。结论 STI571通过阻断BCR－ABL酪氨酸激酶活力，促进K562细胞凋亡达到抑制细胞增殖的目的，而对不表达BCR－ABL的细胞株无诱导凋亡的作用，提示STI571的作用具有一定的特异性。     

酪氨酸激酶抑制剂STI571对慢性粒细胞性白血病K562细胞周期的作用及机制

目的:研究酪氨酸激酶抑制剂STI571对K562细胞周期的作用及机制.方法:以逆转录-聚合酶链反应和Western blot方法分别检测ST1571处理K562细胞12、24、48 h后p38、ERK、cyclin D2、cyclin E、p27 mRNA和蛋白的表达,并以流式细胞仪检测其不同时间点细胞周期的变化.结果:ST1571处理后K562细胞p38、ERK、cyclin D2、cyclin E mRNA和蛋白表达降低,p27 mRNA和蛋白表达增高.G<0/G1期细胞增多,s期细胞减少,与用药前比较差异均有统计学意义(P<0.05).结论:STI571可能通过丝裂原活化蛋白激酶途径影响细胞周期调控蛋白,最终抑制K562细胞的增殖.     

BCR-ABL酪氨酸激酶抑制剂STI571的研究进展

蛋白酪氨酸激酶 (ＰｒｏｔｅｉｎＴｙｒｏｓｉｎｅＫｉｎａｓｅ ,ＰＴＫ)是细胞信号传递途径中的一个重要组成部分 ,对调节细胞生长、分化中起着重要的作用。ＰＴＫ活力增高在一些恶性血液病发病中起着决定性的作用[1] ,其中最具代表性的是ＢＣＲ ＡＢＬ ＰＴＫ与慢性髓性白血病 (ＣＭＬ)的关系。研究结果强烈提示 ,特异性的ＰＴＫ抑制剂可作为一种新型的治疗手段 ,特殊设计的针对ＰＴＫ作用部位的药物可影响底物蛋白上ＰＴＫ的磷酸化 ,从而阻断肿瘤蛋白的信号传输 ,诱导肿瘤细胞凋亡。ＢＣＲ ＡＢＬ酪氨酸激酶抑制剂ＳＴＩ5 71,临床前期研…     

酪氨酸激酶抑制剂STI571对慢性粒细胞性白血病K562细胞周期的作用及机制

目的:研究酪氨酸激酶抑制剂STI571对K562细胞周期的作用及机制.方法:以逆转录-聚合酶链反应和Western blot方法分别检测ST1571处理K562细胞12、24、48 h后p38、ERK、cyclin D2、cyclin E、p27 mRNA和蛋白的表达,并以流式细胞仪检测其不同时间点细胞周期的变化.结果:ST1571处理后K562细胞p38、ERK、cyclin D2、cyclin E mRNA和蛋白表达降低,p27 mRNA和蛋白表达增高.G<0/G1期细胞增多,s期细胞减少,与用药前比较差异均有统计学意义(P<0.05).结论:STI571可能通过丝裂原活化蛋白激酶途径影响细胞周期调控蛋白,最终抑制K562细胞的增殖.     

早幼粒细胞白血病蛋白在髓系白血病中的表达及其对慢性粒细胞白血病增殖的影响分析

目的 探讨早幼粒细胞白血病(PML)蛋白在髓系白血病中的表达情况及其对慢性粒细胞白血病细胞增殖的抑制作用.方法 收集髓系白血病患者(髓系白血病组)60例,非肿瘤性血液病患者(对照组)15例,患者骨髓制备石蜡切片,采用免疫荧光技术观察PML在细胞内的分布和表达;提取骨髓单核细胞总RNA,采用逆转录聚合酶链反应观察PML mRNA的表达情况;提取骨髓总蛋白,采用蛋白质印迹法(Western Blot)观察PML蛋白的表达情况;K562细胞分别转染空质粒(MSCV组)、截短失活PML(DN组)和野生型PML(Wt组),测定PML基因对K562细胞增殖和集落产生的影响.结果 非肿瘤性血液病患者的PML表达聚集在细胞核内,而髓系白血病患者的PML分散表达在细胞核和胞质内;髓系白血病组PML mRNA水平0.356±0.092显著低于对照组的表达0.536±0.066(t=7.11,P<0.01);髓系白血病组PML蛋白相对表达水平0.189±0.032显著低于对照组0.323±0.025(t=16.10,P<0.01);DN(转染截短失活PML)组,MSCV(转染空质粒)组和Wt(转染野生型PML)组在450 nm波长下吸光度值(Optical Density450,OD450)和集落生成单位(Colony-Forming Units,CFU)的数据均差异有统计学意义(F=34.28,25.39,P<0.05),q检验结果显示,均为Wt组的数值低于DN组和MSCV组.结论 髓系白血病患者中PML蛋白表达水平下降导致细胞异常增殖可能是其发病机制.     

新生霉素对STI571耐药K562/G01细胞的作用

目的研究热休克蛋白90(Hsp90)抑制剂新生霉素(novobiocin,NB)对STI571耐药K562/G01细胞生长的抑制作用,并研究NB和STI571联合应用对STI571敏感和耐药细胞的作用,并进一步探讨该作用与Bcr-Abl蛋白水平和Bcr-Abl激酶水平的关系。方法用MTT法检测NB对K562和K562/G01细胞生长的抑制作用,用金氏公式评价药物合用体外是否有协同作用,用蛋白免疫印迹法检测Bcr-Abl蛋白水平和p-Tyrosine水平。结果NB能抑制K562和K562/G01细胞增殖,IC50分别是0.4353mmol.L-1和0.3490mmol.L-1;NB和STI571联合应用对STI571敏感和耐药细胞均有协同作用;NB能使K562和K562/G01细胞内Bcr-Abl和p-Tyrosine蛋白含量减少。结论NB通过减少Bcr-Abl和p-Tyrosine蛋白含量,抑制STI571耐药细胞K562/G01的增殖,NB和STI571有协同效应。     

异甘草酸镁对慢性髓细胞性白血病K562细胞系增殖的抑制作用

目的：观察异甘草酸镁对慢性髓细胞白血病K562细胞系增殖的抑制作用。方法：将异甘草酸镁以1640培养液倍比稀释成10,1,10-1,10-2,10-3,10-4,10-5,10-6g·L-1共8个浓度组,分别处理增殖期K562细胞,镜下观察不同时间点各浓度组细胞生长情况,应用CCK-8法检测细胞增殖能力,绘制生长曲线,计算抑制率和半数抑制浓度（IC50）。结果：在给药第3天,浓度大于10-3g·L-1的异甘草酸镁对K562细胞增殖具有抑制作用（P〈0.05）,细胞倍增时间为48h,并且具有时间和浓度依赖性。其中,10g·L-1和1g·L-1异甘草酸镁的抑制作用最强（P〈0.01）,IC50约为1.6g·L-1。结论：异甘草酸镁对K562细胞的增殖具有抑制作用,为临床应用异甘草酸镁预防和治疗白血病化疗相关肝损伤提供实验依据。     

TKI耐药慢性髓系白血病患者ABL激酶区点突变的相关因素分析

目的 探索酪氨酸激酶抑制剂(TKI)耐药慢性髓系白血病(CML)患者ABL激酶区点突变的相关因素.方法对2014年1月至2017年12月于重庆医科大学附属第一医院诊断为CM L伴ABL激酶区点突变的18例耐药患者与19例不伴点突变的耐药患者的临床资料进行回顾性分析,应用单因素及多因素logistic回归分析探讨影响激酶...     

三氧化二砷与甲磺酸伊马替尼对慢性粒细胞白血病原代细胞增殖与凋亡的协同作用研究

目的：探讨三氧化二砷（Arsenic trioxide,ATO）对甲磺酸伊马替尼（STI571）在慢性粒细胞白血病（CML）原代细胞中对细胞增殖及凋亡的影响。方法：采用四甲基偶氮唑蓝（MTT）法观察STI571单独使用与联用ATO对慢性粒细胞白血病原代细胞增殖抑制的变化情况。流式细胞仪检测细胞凋亡。结果：无毒剂量的ATO（0.15μmol·L-1）联用STI571（IC500.324±0.011μmol·L-1）较单独使用STI571（0.580±0.007μmol·L-1）时对细胞抑制率显著增大,IC50下降1.79倍（P〈0.05）。细胞经ATO（0.15μmol·L-1）、STI571（0.5μmol·L-1）联合处理24h、48h时,细胞凋亡率增大为15.6%、50.7%,协同作用为增强（＋＋）。结论：ATO能增强STI571对CML原代细胞敏感性,能促进细胞凋亡与STI571具有增强的协同作用。     

Quantification of the anti-leukemia drug STI571 (Gleevec) and its metabolite (CGP 74588) in monkey plasma using a semi-automated solid phase extraction procedure and liquid chromatography-tandem mass spectrometry

Signal Transduction Inhibitor 571 (STI571, formerly known as CGP 57148B) or Gleevec™ received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 (Gleevec™) is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared with existing treatments prompted an equally profound increase in the pace of development of Gleevec™. The duration from first dose in man to completion of the New Drug Application (NDA) filing was less than 3 years. In addition, recently, FDA approved Gleevec™ for the treatment of gastrointestinal stromal tumor (GIST). In order to support all toxicokinetic (TK) studies with sufficient speed to meet various target dates, a semi-automated procedure using solid phase extraction (SPE) was developed and validated. A Packard Multi-Probe I and a SPE step in a 96-well plate format were utilized. A 3M Empore octyl (C₈)-standard density 96-well plate was used for plasma sample extraction. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization (APCI) interface operated in positive ion mode was used for detection. Lower limits of quantification of 1.00 and 2.00 ng/ml were attained for STI571 and its metabolite, CGP 74588, respectively. The method proved to be rugged and allowed the simultaneous quantification of STI571 and CGP 74588 in monkey plasma. Herein, assay development, validation, and representative concentration–time profiles obtained from TK studies are presented.     

Combination of SK-7041, one of novel histone deacetylase inhibitors, and STI571-induced synergistic apoptosis in chronic myeloid leukemia

Although STI571 still plays a key role in the treatment of chronic myeloid leukemia, emergence of resistance to STI571 is a major obstacle to successful outcome. Therefore, new agents that increase the sensitivity of chronic myeloid leukemia cells to STI571 are urgently required. SK-7041 is a novel hybrid synthetic histone deacetylase inhibitor derived from the hydroxamic acid of trichostatin A and pyridyl ring of MS-275. Its cytotoxic effects were examined both as a single agent and in combination with STI571 in acute and chronic myeloid leukemia. SK-7041 exhibited growth inhibition of leukemia cells by downregulation of CDK4, cyclin E and cyclin B1 expression, and by upregulation of p21 expression with subsequent activation of the mitochondria-mediated caspase pathway. SK-7041 showed synergism on growth inhibition, cell cycle arrest and induction of apoptosis in chronic myeloid leukemia (K562) when combined with STI571. The synergistic effect was mediated through the same mechanism as in SK-7041 alone, involving reduction of cyclin D1 and induction of p21. Taken together, our findings suggest that SK-7041 is active against leukemia and offers new prospects for overcoming STI571 resistance in chronic myeloid leukemia.     

Mechanisms of resistance imatinib (STI571) in preclinical models and in leukemia patients.

The tyrosine kinase inhibitor imatinib (STI571, Glivec) blocks the activity of the BCR/ABL oncogene and induces hematologic remissions in the majority of patients with chronic myeloid leukemia (CML). Glivec is an aminopyrimidine derivative that interacts with the ATP-binding site within the kinase domain of ABL and several other tyrosine kinases, including c-KIT, PDGF beta receptor, and ARG. The compound is currently in phase III clinical trials. Although patients with chronic phase CML have been found to develop drug resistance only rarely so far, patients in more advanced phases of the leukemia develop resistance frequently. The available information on Glivec resistance will be reviewed.     

Imatinib (STI571) resistance in chronic myelogenous leukemia: molecular basis of the underlying mechanisms and potential strategies for treatment

Following the paradigm set by STI571, protein tyrosine kinase inhibitors are emerging as a promising class of drugs, capable of modulating intracellular signaling and demonstrating therapeutic potential for the treatment of proliferative diseases. Although the majority of chronic phase CML patients treated with STI571 respond, some patients, especially those with more advanced disease, relapse. This article reviews the reasons for relapse and, in particular, analyses resistance resulting from Bcr-Abl tyrosine kinase domain mutations at the molecular level. Arguments are based upon the structure of the STI571-Abl complex, which is compared to the crystal structures of PD173955-Abl and PD180970-Abl, which bind to the kinase differently. Strategies to potentially circumvent or overcome resistance are discussed.     

The novel pyrrolo-1,5-benzoxazepine, PBOX-21, potentiates the apoptotic efficacy of STI571 (imatinib mesylate) in human chronic myeloid leukaemia cells

The Bcr-Abl kinase inhibitor, STI571, is the first line treatment for chronic myeloid leukaemia (CML), but the recent emergence of STI571 resistance has led to the examination of combination therapies. In this report, we describe how a novel non-toxic G1-arresting compound, pyrrolo-1,5-benzoxazepine (PBOX)-21, potentiates the apoptotic ability of STI571 in Bcr-Abl-positive CML cells. Co-treatment of CML cells with PBOX-21 and STI571 induced more apoptosis than either drug alone in parental (K562S and LAMA84) and STI571-resistant cells lines (K562R). This potentiation of apoptosis was specific to Bcr-Abl-positive leukaemia cells with no effect observed on Bcr-Abl-negative HL-60 acute myeloid leukaemia cells. Apoptosis induced by PBOX-21/STI571 resulted in activation of caspase-8, cleavage of PARP and Bcl-2, upregulation of the pro-apoptotic protein Bim and a downregulation of Bcr-Abl. Repression of proteins involved in Bcr-Abl transformation, the anti-apoptotic proteins Mcl-1 and Bcl-_XL was also observed. The combined lack of an early change in mitochondrial membrane potential, release of cytochrome c and cleavage of pro-caspase-9 suggests that this pathway is not involved in the initiation of apoptosis by PBOX-21/STI571. Apoptosis was significantly reduced following pre-treatment with either the general caspase inhibitor Boc-FMK or the chymotrypsin-like serine protease inhibitor TPCK, but was completely abrogated following pre-treatment with a combination of these inhibitors. This demonstrates the important role for each of these protease families in this apoptotic pathway. In conclusion, our data highlights the potential of PBOX-21 in combination with STI571 as an effective therapy against CML.     

In bcr-abl-positive myeloid cells resistant to conventional chemotherapeutic agents, expression of Par-4 increases sensitivity to imatinib (STI571) and histone deacetylase-inhibitors

In a variety of malignant cells the prostate-apoptosis-response-gene-4 (Par-4) induces increased sensitivity towards chemotherapeutic agents by down-regulating anti-apoptotic B-cell lymphoma-gene 2 (Bcl-2). Hypothesizing that Par-4 also influences apoptosis in myeloid cell lines, we tested this hypothesis by stably transfecting bcr-abl transformed-K562 cells with a Par-4-expressing vector. Here we demonstrate that over-expression of Par-4 in K562 cells up-regulates expression levels of Bcl-2 and death-associated protein (Daxx). Upon treatment with different chemotherapeutic agents, Fas- or TRAIL agonistic antibodies, Par-4-positive cells did not exhibit an increased rate of apoptosis as compared to Par-4-negative control cells. However, incubation with histone deacetylase (HDAC)-inhibitors Trichostatin A (TSA) and LAQ824 or the tyrosinkinase inhibitor Imatinib (STI571) increased the rate of apoptosis in Par-4-positive K562 cells. Assessing the underlying molecular mechanisms for the Par-4-induced response to HDAC-inhibitors and STI571 we provide evidence, that these effects are associated with a down-regulation of Daxx, enforced activation of caspases and enhanced cleavage of cellular inhibitor of apoptosis (cIAP)-1 and -2.