A non-ATP-competitive inhibitor of BCR-ABL overrides imatinib resistance

Imatinib, which is an inhibitor of the BCR-ABL tyrosine kinase, has been a remarkable success for the treatment of Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemias (CMLs). However, a significant proportion of patients chronically treated with imatinib develop resistance because of the acquisition of mutations in the kinase domain of BCR-ABL. Mutations occur at residues directly implicated in imatinib binding or, more commonly, at residues important for the ability of the kinase to adopt the specific closed (inactive) conformation to which imatinib binds. In our quest to develop new BCR-ABL inhibitors, we chose to target regions outside the ATP-binding site of this enzyme because these compounds offer the potential to be unaffected by mutations that make CML cells resistant to imatinib. Here we describe the activity of one compound, ON012380, that can specifically inhibit BCR-ABL and induce cell death of Ph+ CML cells at a concentration of <10 nM. Kinetic studies demonstrate that this compound is not ATP-competitive but is substrate-competitive and works synergistically with imatinib in wild-type BCR-ABL inhibition. More importantly, ON012380 was found to induce apoptosis of all of the known imatinib-resistant mutants at concentrations of <10 nM concentration in vitro and cause regression of leukemias induced by i.v. injection of 32Dcl3 cells expressing the imatinib-resistant BCR-ABL isoform T315I. Daily i.v. dosing for up to 3 weeks with a >100 mg/kg concentration of this agent is well tolerated in rodents, without any hematotoxicity.     

Successful Treatment of Idiopathic Hypereosinophilic Syndrome with Imatinib Mesylate: A Case Report

Patients with idiopathic hypereosinophilic syndrome (HES) show persistent hypereosinophilia of unknown etiology that is associated with end-organ damage. Different treatments, including the use of corticosteroids and cytotoxics, have been investigated for HES with modest success. We describe a patient with HES who had significant end-organ damage from hypereosinophilia and remained refractory to conventional therapy. Therapy with imatinib mesylate, a selective tyrosine kinase inhibitor that is highly effective in treating patients with BCR-ABL-positive chronic myeloid leukemia, was tried with the patient. The result was impressive, with hematologic remission achieved after 12 days of administration. Our finding concurs with recent reports that imatinib mesylate may be a promising agent in the treatment of some cases of HES.     

Imatinib mesylate inhibits platelet-derived growth factor activity and increases chemosensitivity in feline vaccine-associated sarcoma

Feline vaccine-associated sarcoma (VAS) is a biologically aggressive soft-tissue sarcoma that can develop at sites where inactivated feline vaccines have been administered. We showed that platelet-derived growth factor (PDGF) and its receptor (PDGFR) play a role in the growth of VAS cells. The presence of PDGFR- was confirmed in each of five VAS cell lines evaluated, one non-vaccine-associated feline fibrosarcoma (FSA) cell line and a feline fibroblast-derived cell line. The PDGF/PDGFR signaling pathway was inhibited in the VAS cell lines and the FSA cell line using the tyrosine kinase inhibitor imatinib mesylate (formerly called STI-571). Imatinib inhibited PDGF-BB-induced autophosphorylation of PDGFR in VAS cells and feline FSA cells in vitro in a dose-dependent manner. Imatinib also significantly inhibited growth of feline VAS tumors in a murine xenograft model. Imatinib reversed the protective effect of PDGF-BB on growth inhibition by doxorubicin and carboplatin. PDGF-BB protected VAS cells from serum starvation and doxorubicin-induced apoptosis but not carboplatin-induced apoptosis, and imatinib eliminated this protection. These observations suggest that imatinib inhibits PDGFR tyrosine kinase activity in feline soft tissue sarcomas in vitro and inhibits tumor growth in a xenograft model.Abbreviations C/10 Complete minimal essential medium supplemented with 10% FBS - CPT Carboplatin - DOX Doxorubicin - EGF Epidermal growth factor - FBS Fetal bovine serum - FSA Fibrosarcoma - HGF Hepatocyte growth factor - IGF-1 Insulin-like growth factor-1 - MTS 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium - PDGF Platelet-derived growth factor - PDGFR Platelet-derived growth factor receptor - PI Propidium iodide - VAS Vaccine-associated sarcomaThis work was supported in part by the American Veterinary Medical Association Feline Sarcoma Task Force. Imatinib mesylate was provided by Novartis Pharmaceuticals, Inc.     

白血病基因产物靶向治疗的基础和临床研究

全反式维甲酸(ATRA)和三氧化二砷(As2O3)治疗急性早幼粒细胞性白血病(APL)获得了很大成功，已经成为白血病靶向治疗研究的代表性模式ATRA与As2O3的作用靶点均为异常转录因子PML—RARα，前者通过针对RARα，而后者通过PML SUMO化后使PML—RARα致病蛋白降解，导致APL细胞分化和凋亡。ATRA与As2O3联合治疗初发APL，证实了两药的相互协同作用，获得了迄今为止成人急性白血病治疗的最好疗效。酪氨酸激酶抑制剂格力维(Gleevec)在慢性粒细胞白血病(CML)治疗中获得了成功。联合应用格力维与砷剂治疗CML已在临床和实验中初步证实其有效性，这一治疗方案是基于针对ABL异常的酪氨酸激酶活性与降解BCR—ABL融合蛋白的双重靶向作用。白血病多靶点联合治疗的思路将进一步拓展至ANLL-M2b型白血病，为该类白血病提供新的治疗方案，有可能使该类白血病获得更为有效的治疗效果。     

119例胃肠道间质瘤的临床诊疗分析

目的:探讨胃肠间质瘤(gastrointestinal stromal tumor,GIST)的临床特点。方法:对1995～2007年收治的119例GIST患者的临床资料进行回顾性分析。结果:免疫组织化学阳性表达率CD117为94.1%(112/119),CD34为77.3%(92/119),119例均进行外科手术,病理诊断为良性21例,恶性89例,低度恶性9例。随访114例,随访时间1～13年,良、恶性肿瘤分别为21和98例,59例转移或局部复发并死亡。结论:GIST缺乏特征性临床表现,术前确诊率低,CD117及CD34等免疫标记物配合使用可以提高胃肠道间质瘤的病理诊断准确率。预后与肿瘤大小、性质和复发转移有关(P<0.05)。     

格列卫对卵巢癌细胞COC1增殖及血管形成的影响

目的探讨格列卫(gleevec)对耐药卵巢癌细胞COC1增殖、顺铂敏感性和血管形成的影响,为临床应用格列卫治疗难治性卵巢癌提供实验依据。方法2006年9月至2007年5月于哈尔滨医科大学第一临床医学院采用四甲基偶氮唑蓝(MTT)法检测格列卫对细胞增殖的影响;采用ELISA法检测格列卫对COC1表达血管内皮细胞生长因子(VEGF)和内皮抑素(endostatin)的影响。结果格列卫对COC1细胞增殖的抑制作用表现出浓度依赖性,并显著提高了其对顺铂的敏感性;格列卫对COC1表达VEGF具有明显的抑制作用,格列卫对COC1表达内皮抑素具有明显促进作用,并呈浓度依赖性。结论格列卫能够抑制顺铂耐药卵巢癌细胞COC1的增殖,并显著增强其对顺铂的敏感性;格列卫对抑制肿瘤细胞产生VEGF具有明显的作用。     

The Wnt-dependent signaling pathways as target in oncology drug discovery

Summary Our current understanding of the Wnt-dependent signaling pathways is mainly based on studies performed in a number of model organisms including, Xenopus, Drosophila melanogaster, Caenorhabditis elegans and mammals. These studies clearly indicate that the Wnt-dependent signaling pathways are conserved through evolution and control many events during embryonic development. Wnt pathways have been shown to regulate cell proliferation, morphology, motility as well as cell fate. The increasing interest of the scientific community, over the last decade, in the Wnt-dependent signaling pathways is supported by the documented importance of these pathways in a broad range of physiological conditions and disease states. For instance, it has been shown that inappropriate regulation and activation of these pathways is associated with several pathological disorders including cancer, retinopathy, tetra-amelia and bone and cartilage disease such as arthritis. In addition, several components of the Wnt-dependent signaling pathways appear to play important roles in diseases such as Alzheimer’s disease, schizophrenia, bipolar disorder and in the emerging field of stem cell research. In this review, we wish to present a focused overview of the function of the Wnt-dependent signaling pathways and their role in oncogenesis and cancer development. We also want to provide information on a selection of potential drug targets within these pathways for oncology drug discovery, and summarize current data on approaches, including the development of small-molecule inhibitors, that have shown relevant effects on the Wnt-dependent signaling pathways.     

格列卫诱导癌蛋白半乳凝集素-3通过溶酶体降解并促进胶质母细胞瘤U87细胞的凋亡

目的 探讨格列卫诱导胶质母细胞瘤细胞株U87细胞凋亡及其促进癌蛋白半乳凝集素-3（Gal-3）降解的分子机制.方法 利用细胞免疫染色法和提取细胞溶酶体的方法观察格列卫处理细胞后溶酶体中Gal-3蛋白量的变化;U87细胞分别用格列卫和/或STS及溶酶体抑制剂ConA处理后,用Western blot方法检测细胞中Gal-3蛋白量的改变;SubG1法检测U87细胞在格列卫及STS单药处理和联合处理时各组细胞凋亡率.结果 格列卫处理U87细胞使Gal-3蛋白进入溶酶体并发生蛋白的降解;格列卫能够诱导U87细胞发生凋亡,与STS联合使用有协同诱导U87细胞凋亡的作用.结论 格列卫能够诱导U87细胞株中Gal-3通过溶酶体降解,并使肿瘤细胞对凋亡诱导剂的敏感性增加.     

Failure of CDKN2A/B (INK4A/B-ARF)-mediated tumor suppression and resistance to targeted therapy in acute lymphoblastic leukemia induced by BCR-ABL

Deletions of the CDKN2A/B tumor suppressor locus and of the IKAROS and PAX5 genes that promote B-lineage development occur frequently in lymphoid, but not myeloid leukemias initiated by the BCR-ABL tyrosine kinase. Why is this the case, and how do these genetic lesions contribute to an aggressive disease that fails to durably respond to targeted kinase inhibitors?     

胃肠道间质瘤相关基因突变体对格列卫敏感性研究*

目的:探讨胃肠道间质瘤相关基因突变体KIT Ins IPYD579 和PDGFRA L 839P 对格列卫治疗的药物敏感性。方法:采用脂质体法将胃肠道间质瘤相关基因突变体KIT Del559-560、KIT Ins IPYD579、PDGFRA D 842V 及PDGFRA L 839P 重组质粒分别瞬时转染中国仓鼠卵巢上皮细胞系（CHO）,表达24h 后与格列卫共孵育90min,用Western-blot法检测的相关蛋白表达及其磷酸化状态。另外,用MTT 法检测各组稳转PDGFRA 基因突变体的CHO细胞与不同浓度格列卫共孵育72h 后的增殖变化。结果:当格列卫浓度为0.1 μ M 时,转染KIT Del559-560 重组质粒的CHO细胞磷酸化KIT 蛋白表达量明显降低。当格列卫浓度为1 μ M 时,转染KIT Ins IPYD579 和PDGFRA L 839P 重组质粒的CHO细胞的相应蛋白磷酸化形式不能检出。而转染PDGFRA D 842V 重组质粒的CHO细胞直至格列卫浓度提高至5 μ M 时,其磷酸化PDGFRA 蛋白表达水平仍无明显降低。MTT 法显示:当格列卫浓度提高至1 μ M 时,转染PDGFRA L 839P 重组质粒的CHO细胞增殖百分比明显降低,而转染PDGFRA D 842V 重组质粒的CHO细胞增殖百分比直至格列卫浓度为5 μ M 时仍无明显变化。结论:格列卫在短时间内可使PDGFRA L 839P 或KIT Ins IPYD579 突变体磷酸化蛋白表达减少,长期作用时对表达PDGFRA L 839P 突变体的细胞增殖具有明显的抑制作用。