小分子Bcl-2抑制剂的研究与开发

综述细胞凋亡的主要机制、Bcl-xL蛋白结构以及各类小分子Bcl-2抑制剂的研究与开发。高水平表达Bcl-2家族抗凋亡蛋白（如Bcl-2、Bcl-xL等）可导致肿瘤细胞的凋亡过程受阻，并对传统放、化疗产生抵抗性，而下调过表达Bcl-2和Bcl-xL蛋白则可诱导肿瘤细胞凋亡，且逆转肿瘤细胞对治疗的抵抗性或耐药性。因此，作为潜在的癌症治疗策略，以Bcl-2家族蛋白为靶点的小分子抑制剂已成为当今研究热点，X-射线晶体衍射、核磁共振技术、小分子数据库和计算机辅助药物设计等技术也广泛应用于小分子Bcl-2抑制剂的开发。     

精胺氧化酶抑制剂的筛选及抗肿瘤活性评价

目的 筛选多胺代谢关键酶精胺氧化酶小分子抑制剂,并评价其对人肺癌A549细胞的精胺氧化酶活性抑制效应、抗肿瘤作用及分子机制。方法 以精胺和精胺氧化酶复合物结构为基础,用计算机辅助药物设计技术,在化学数据库中虚拟筛选获得候选的小分子抑制剂。以A549细胞为肿瘤细胞模型,利用化学发光法、HPLC法分析小分子抑制剂对精胺氧化酶活性抑制及多胺含量的影响;采用MTT法、流式细胞术检测小分子抑制剂对细胞增值、细胞周期、诱导细胞凋亡的影响;在倒置荧光显微镜、透射电子显微镜下观察小分子抑制剂诱导细胞自噬小体的形成;Western blot法分析小分子抑制剂对细胞周期蛋白(Cyclin B1、p21、Cyclin D)、凋亡相关蛋白(Bax、Bcl-2、细胞色素C)和自噬相关蛋白(LC3、P62)表达的影响。结果 筛选出有效抑制精胺氧化酶活性的新型小分子抑制剂SI-1338,对精胺氧化酶的半数抑制浓度为880μmol·L^-1。SI-1338可有效抑制A549细胞中精胺氧化酶活性,干扰多胺代谢,减少总多胺的含量;抑制A549细胞的增殖,周期蛋白Cyclin B1、p21、Cyclin...     

Bcl-2蛋白的小分子抑制剂

Bcl-2蛋白家族在调节细胞凋亡中发挥重要作用，人类恶性肿瘤细胞高表达Bcl-2和Bcl-XL，而高表达这些抗凋亡分子的细胞对于化疗药物有抗性，因此，以Bcl-2家族蛋白为靶点的小分子抑制剂成为很有潜力的可用于多种肿瘤治疗的药物，通过下调Bcl-2和Bcl-XL的表达直接影响肿瘤细胞的存活及其对化疗药物的抗性。     

Mcl-1蛋白的结构、功能及其抑制剂的研究进展

细胞凋亡与许多人类疾病的发生密切相关,过度凋亡引发神经退行性疾病,而抑制凋亡则与肿瘤等疾病的产生有关.研究表明,Bcl-2蛋白家族在细胞凋亡中发挥重要作用,特别是近几年对Bcl-2蛋白家族成员Mcl-1及其抑制剂研究越来越多.本文介绍了Mcl-1蛋白的结构与功能特点,综述了近几年作为抗肿瘤药物的Mcl-1抑制剂的研究进展.     

凋亡调节蛋白Bcl-2家族在非小细胞肺癌中的表达

目的在手术切除的原发性非小细胞肺癌(NSCLC)标本中检测凋亡调节蛋白Bcl-2家族中的Bcl-2、Bax和Mcl-1的表达特征和预后的意义。方法用针对人体的Bcl-2、Bax与Mcl-1的特异性鼠源性抗体采用免疫组化法,检测它们在50例NSCLC患者手术切除的石蜡包埋标本中的表达情况,并结合临床病理分型和追踪预后分析其表达的意义。结果(1)非小细胞性肺癌标本中抗凋亡因子Bcl-2和Mcl-1分别有15例(30%)和29例(58%)表达阳性,有23例(46%)的标本中有促凋亡因子Bax表达阳性。Mcl-1与Bax的表达之间存在正相关(P=0.06)。Bcl-2、Bax和Mcl-1的免疫组化染色以胞浆为主。(2)Mcl-1与Bax在肺癌的不同临床病理分型中没有差异(分别为P>0.250和P>0.900)。(3)Bcl-2的表达与原发性NSCLC手术切除患者总的无复发生存率(P=0.02)和无转移生存率(P<0.01)呈负相关,Mcl-1与Bax的表达与预后无关。结论在NSCLC中,Bcl-2家族蛋白Bcl-2、Mcl-1和Bax的表达等都很常见。Mcl-1的抗凋亡功能可能是通过在蛋白质水平与Bax相互作用形成异二聚体,拮抗Bax的促进凋亡功能而实现的。可能由于它们在凋亡中复杂的相互作用,凋亡调节蛋白Bcl-2家族的表达对NSCLC的临床预后没有直接的影响。     

应用组织芯片技术研究胃癌组织中Mcl-1蛋白的表达及其意义

目的探讨胃癌组织髓样细胞白血病蛋白-1(Mcl-1)蛋白的表达与临床病理特征的相关性及其与胃癌发生、发展的关系。方法用组织芯片和免疫组化的方法检测148例胃癌组织、20例胃正常组织(含正常胃黏膜组织及癌旁正常胃组织)中Mcl-1蛋白的表达。结果胃癌组织、胃正常组织中均有Mcl-1蛋白的表达,定位于细胞浆中,着色呈淡黄色至深棕色;胃癌组织、胃正常组织Mcl-1蛋白阳性表达率分别为83.78%(124/148)、60.00%(12/20),差异具有统计学意义(χ2=6.464,P=0.011)。胃癌组织中Mcl-1蛋白的表达随肿瘤分化程度的降低而增强,与是否伴有淋巴结转移相关;但与患者的年龄、性别、肿瘤大小、浸润深度等无关。结论胃癌组织中Mcl-1蛋白的表达增高,与胃癌的发生、分化程度、淋巴结转移密切相关。     

索拉菲尼增强TRAIL 诱导人肝癌细胞凋亡的作用及机制探讨

目的观察索拉菲尼(Sorafenib)是否能增强肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导人肝癌细胞凋亡并探讨其作用机制。方法体外培养人肝癌HepG2细胞,MTT法测定细胞增殖活性,碘化丙啶(PI)染色流式细胞术(FCM)和细胞凋亡ELISA检测试剂盒检测细胞凋亡,Western blotting分析Mcl-1的表达。结果索拉菲尼具有增强TRAIL诱导人肝癌HepG2细胞凋亡的作用,并呈剂量和时间依赖的方式抑制Mcl-1的表达。Mcl-1过表达能抑制索拉菲尼增强TRAIL诱导HepG2细胞凋亡的作用。结论索拉菲尼通过抑制Mcl-1的蛋白表达增强TRAIL诱导人肝癌细胞凋亡的作用。     

缺氧诱导因子-1α及其抑制剂的研究进展

缺氧诱导因子-1α(hypoxia-inducible factor-1α,HIF-1α)在缺氧肿瘤细胞尤其是实体瘤中都存在着过度表达,它能够控制下游100多种基因的表达,包括血管内皮生长因子(VEGF)、葡萄糖转移酶-1(GLUT-1)、酪氨酸激酶(c-Met)等,对肿瘤细胞的增殖、转移、侵入、凋亡以及糖代谢都有至关重要的作用。已经证明许多已经上市的和进入临床研究的药物都具有HIF-1α抑制活性。近几年,设计合成的多种类型的新型小分子HIF-1抑制剂,有望成为新一类抗肿瘤药物。本文主要对近年来设计合成的新型HIF-1α抑制剂进行综述。     

小分子Pin1抑制剂XP08075的抗肿瘤作用研究

目的：本研究旨在观察小分子肽脯氨酰顺反异构酶Pin1抑制剂XP08075的体外抗肿瘤作用及其对细胞周期及Pin1相关信号通路的影响。方法：WesternBlot法检测多种肿瘤细胞株的Pin1蛋白表达水平,选定相对低表达Pin1的HepG2细胞,脂质体法稳定转染pCMV-Pin1质粒构建高表达Pin1的肝癌细胞模型,MTT检测XP08075对不同肿瘤细胞、亲本HepG2细胞以及高表达Pin1HepG2细胞的生长抑制作用;生长曲线及流式细胞术检测XP08075对肿瘤细胞倍增时间及细胞周期的影响：WesternBlot分析XP08075对Pin1蛋白水平以及Pin1相关信号通路的影响。结果：MTT实验显示XP08075能显著抑制各种肿瘤细胞的增殖,IC50在微摩尔水平,且抑制水平与肿瘤细胞Pin1表达水平有-定相关性：成功构建并鉴定Pin1高表达的HepG2肝癌细胞模型,MTT实验显示,高表达Pin1的HepG2细胞较亲本株更敏感;生长曲线结果显示,XP08075能明显降低HepG2及MCF-7细胞的倍增时间;流式细胞术结果显示,XP08075对MCF-7细胞的周期无显著影响;Westernblot结果显示,XP08075可以呈时间依赖的抑制Pin1的蛋白水平,抑制Pin1下游相关蛋白CyclinB1,β—catenin的表达。结论：小分子Pin1抑制剂XP08075可以通过抑制Pin1表达从而抑制肿瘤细胞的增殖,Pin1抑制剂有望成为新型的抗肿瘤治疗靶点。     

抗肿瘤代谢靶标磷酸甘油酸变位酶1及其抑制剂的研究进展

肿瘤细胞的Warburg效应是近期肿瘤代谢研究的一大热点,磷酸甘油酸变位酶1(PGAM1)在糖酵解生物通路中起着重要作用。报道显示PGAM1在肿瘤细胞中普遍高表达,同时促进细胞增殖过程中的糖酵解和生物合成代谢通路。基于该发现,针对PGAM1进行小分子抑制剂研究成为开发抗肿瘤药物的新思路。综述PGAM1在肿瘤细胞中的功能、意义以及PGAM1抑制剂的开发前景。     

Substituted indole Mcl-1 inhibitors: a patent evaluation (WO2015148854A1)

The myeloid cell leukemia 1 (Mcl-1) protein, an anti-apoptotic member of Bcl-2 family, plays a critical role in the development and maintenance of many cancers and is listed in the ‘top ten’ pathological factors across the diversity of human cancers. The patent described in this evaluation (WO2015148854A1) claimed substituted indole Mcl-1 inhibitors for the treatment of diseases and conditions (e.g., cancer) characterized by the over-expression or dysregulation of Mcl-1 proteins. A variety of 2-position substituents distinguished indole Mcl-1 inhibitors claimed in this patent from another two patents by AbbVie Inc. (WO2008131000A2 and WO2008130970A1). They exhibited low-nanomolar binding affinities and >100-fold selectivity over Bcl-2 and Bcl-xL in vitro, and low-micromolar killing abilities against a panel of tumour cell lines. Moreover, the compounds in this patent revealed that the structural basis for selective Mcl-1 inhibitors may not completely depend on the 5 known binding hot-spots, and conformational flexibility of Mcl-1 protein could contribute to the binding specificity.     

Proteasome inhibitors prevent cisplatin-induced mitochondrial release of apoptosis-inducing factor and markedly ameliorate cisplatin nephrotoxicity

We demonstrate the effect of proteasome inhibitors in mitochondrial release of apoptosis-inducing factor (AIF) in cisplatin-exposed renal tubular epithelial cells (LLC-PK₁ cells) and in a model of cisplatin nephrotoxicity. Immunofluorescence and subcellular fractionation studies revealed cisplatin-induced translocation of AIF from the mitochondria to nucleus. Mcl-1, a pro-survival member of the Bcl-2 family, is rapidly eliminated on exposure of renal cells to cisplatin. Proteasome inhibitors PS-341 and MG-132 blocked cisplatin-induced Mcl-1 depletion and markedly prevented mitochondrial release of AIF. PS-341 and MG132 also blocked cisplatin-induced activation of executioner caspases and apoptosis. These studies suggest that proteasome inhibitors prevent cisplatin-induced caspase-dependent and -independent pathways. Overexpression of Mcl-1 was effective in blocking cisplatin-induced cytochrome c and AIF release from the mitochondria. Downregulation of Mcl-1 by small interfering RNA promoted Bax activation and cytochrome c and AIF release, suggesting that cisplatin-induced Mcl-1 depletion and associated Bax activation are involved in the release of AIF. Expression of AIF protein in the mouse was highest in the kidney compared to the heart, brain, intestine, liver, lung, muscle, and spleen. In an in vivo model of cisplatin nephrotoxicity, proteasome inhibitor MG-132 prevented mitochondrial release of AIF and markedly attenuated acute kidney injury as assessed by renal function and histology. These studies provide evidence for the first time that the proteasome inhibitors prevent cisplatin-induced mitochondrial release of AIF, provide cellular protection, and markedly ameliorate cisplatin-induced acute kidney injury. Thus, AIF is an important therapeutic target in cisplatin nephrotoxicity and cisplatin-induced depletion of Mcl-1 is an important pathway involved in AIF release.     

Cdk1/cyclin B plays a key role in mitotic arrest-induced apoptosis by phosphorylation of Mcl-1, promoting its degradation and freeing Bak from sequestration

Mcl-1 is one of the major anti-apoptotic members of the Bcl-2 family of apoptotic regulatory proteins. In this study we investigated the role of Mcl-1 in mitotic arrest-induced apoptosis. Vinblastine treatment of KB-3 cells initially resulted in a phosphatase-sensitive mobility shift in Mcl-1 and then subsequent loss of Mcl-1 protein expression which was prevented by MG132, suggesting that phosphorylation triggered proteosome-mediated degradation. Mcl-1 phosphorylation/degradation was a specific response to microtubule inhibition and did not occur in response to lethal concentrations of DNA damaging agents. Vinblastine treatment caused degradation of Mcl-1 in cells in which apoptosis was blocked by Bcl-xL overexpression, indicating that Mcl-1 degradation was not a consequence of apoptosis. A partial reversible phosphorylation of Mcl-1 was observed in synchronized cells traversing mitosis, whereas more extensive phosphorylation and subsequent degradation of Mcl-1 was observed if synchronized cells were treated with vinblastine. Mcl-1 phosphorylation closely paralleled cyclin B expression, and specific cyclin-dependent kinase (Cdk) inhibitors blocked vinblastine-induced Mcl-1 phosphorylation, its subsequent degradation, and improved cell viability after mitotic arrest. Co-immunoprecipitation studies indicated that Mcl-1 was complexed with Bak, but not Bax or Noxa, in untreated cells, and that Bak became activated in concert with loss of Mcl-1 expression. These results suggest that Cdk1/cyclin B plays a key role in mitotic arrest-induced apoptosis via Mcl-1 phosphorylation, promoting its degradation and subsequently releasing Bak from sequestration.     

Pyrogallol-based molecules as potent inhibitors of the antiapoptotic Bcl-2 proteins

We report herein a new class of small-molecule inhibitors of antiapoptotic Bcl-2 proteins. The most potent compound, 7, binds to Bcl-2, Bcl-xL, and Mcl-1 proteins with Ki of 110, 638, and 150 nM, respectively. Compound 7 is highly effective in induction of cell death in breast cancer cells with high levels of Bcl-2, Bcl-xL, and Mcl-1 proteins and represents a promising lead compound for the design of new anticancer drugs.     

Aspirin induces apoptosis in YD-8 human oral squamous carcinoma cells through activation of caspases,down-regulation of Mcl-1, and inactivation of ERK-1/2 and AKT

NSAIDs and COX-2 inhibitors show anti-cancer activities in many cancer cells. In this study, we investigated the effects of NSAIDs (aspirin or indomethacin) and COX-2 inhibitor (NS-398) on growth of YD-8 human oral squamous carcinoma cells. Interestingly, among drugs tested, aspirin showed strongest inhibitory effects on viability and survival of YD-8 cells. Profoundly, aspirin treatment resulted in severe cell shrinkage and nuclear DNA fragmentation in YD-8 cells, suggesting the aspirin-induced apoptosis in YD-8 cells. Data of Western blot further demonstrated that aspirin treatment caused activation of caspases, down-regulation of Mcl-1 protein, dephosphorylation of ERK-1/2 and AKT, and also IκB-α proteolysis-dependent NF-κB activation in YD-8 cells. Aspirin, however, had no effect on expressions of Bcl-2, XIAP, and HIAP-1 in YD-8 cells. Importantly, pretreatment with z-VAD-fmk, a pan-caspase inhibitor blocked the aspirin-induced apoptosis and Mcl-1 down-regulation in YD-8 cells. These findings collectively suggest that aspirin induces apoptosis in YD-8 cells and the induction may be correlated to activation of caspases, caspase-dependent Mcl-1 proteolysis, inactivation of ERK-1/2 and AKT, and activation of NF-κB. It is suggested that aspirin may be applied a potential anti-cancer drug against human oral squamous carcinoma.     

Analysis of Flexibility and Hotspots in Bcl-xL and Mcl-1 Proteins for the Design of Selective Small-Molecule Inhibitors

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Targeting Mcl-1 for the therapy of cancer

INTRODUCTION: Human cancers are genetically and epigenetically heterogeneous and have the capacity to commandeer a variety of cellular processes to aid in their survival, growth and resistance to therapy. One strategy is to overexpress proteins that suppress apoptosis, such as the Bcl-2 family protein Mcl-1. The Mcl-1 protein plays a pivotal role in protecting cells from apoptosis and is overexpressed in a variety of human cancers. AREAS COVERED: Targeting Mcl-1 for extinction in these cancers, using genetic and pharmacological approaches, represents a potentially effectual means of developing new efficacious cancer therapeutics. Here we review the multiple strategies that have been employed in targeting this fundamental protein, as well as the significant potential these targeting agents provide in not only suppressing cancer growth, but also in reversing resistance to conventional cancer treatments. EXPERT OPINION: We discuss the potential issues that arise in targeting Mcl-1 and other Bcl-2 anti-apoptotic proteins, as well problems with acquired resistance. The application of combinatorial approaches that involve inhibiting Mcl-1 and manipulation of additional signaling pathways to enhance therapeutic outcomes is also highlighted. The ability to specifically inhibit key genetic/epigenetic elements and biochemical pathways that maintain the tumor state represent a viable approach for developing rationally based, effective cancer therapies.     

S1, a Novel Pan-BH3 Mimetic, Induces Apoptosis in Mcl-1-Overexpressing Cells Through Bak

Mcl-1, an anti-apoptotic Bcl-2 homolog that has a structurally divergent BH3-binding pocket, non-redundant action model, and unique characteristic of short life confers complete resistance to the BH3 mimetic ABT-737. Herein, we used S1, previously identified as a Mcl-1/Bcl-2 dual inhibitor and a pure BH3 mimetic, to explore the mechanism of Mcl-1's action and supply a strategy to challenge Mcl-1's protection. Apoptosis assay in SMMC-7721, HCT116, and K562 cells demonstrated that S1 can effectively challenge Mcl-1's anti-apoptotic effect. Notably, we discovered an unexpected dynamic change of Mcl-1 that directly correlates with resistance or commitment to apoptosis induced by both ABT-737 and S1. Co-immunoprecipitation assays demonstrated that Mcl-1 increase results from Bim trafficking from Bcl-2 to Mcl-1, while subsequent Bak released by S1 determines Mcl-1 decrease and full-blown apoptosis. Further experiments using Bak shRNA testified that Bak accounts for S1-induced apoptosis and Mcl-1 decrease. Consistently, Bax-deficient DU145 cells are sensitive to S1, whereas Bak-mutant MKN-28 cells are significantly more resistant. The in vitro model could be extended to an in vivo mouse xenograft model in which Mcl-1 confers resistance by increased protein level, and the release of Bak could serve as a biomarker of apoptosis.     

Hydroxymethylglutaryl-coenzyme A reductase inhibitors induce apoptosis in human cardiac myocytes in vitro

Recent findings have implicated hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins, an established class of drugs for the treatment of hypercholesterolemia, in tissue remodeling in the heart. Statins induce apoptosis in different cell culture systems including rat neonatal cardiomyocytes. We investigated possible effects of different statins in vitro in human adult cardiac myocytes on the expression of proteins thought to be involved in the regulation of apoptosis such as Mcl-1, an inhibitor of apoptosis, Bax, an inducer of apoptosis, as well as on cytoplasmic histone-associated-DNA-fragments. Human adult cardiac myocytes (HACM) were treated with different statins at concentrations from 0.01 to 5 microM for up to 96 h. Whereas the lipophilic statin simvastatin at a concentration of 5 microM downregulated Mcl-1 mRNA by 49%, the hydrophilic pravastatin had no effect. Bax mRNA levels were not affected by neither of the statins. Simvastatin but not pravastatin reduced Mcl-1 protein expression whereas Bax protein was not detectable in HACM as determined by Western blotting. Simvastatin, atorvastatin and fluvastatin induced an up to seven-fold increase in histone-associated-DNA-fragments whereas pravastatin did not. Simvastatin up regulated histone-associated-DNA-fragments dose-dependently, and mevalonate and geranylgeranyl pyrophosphate reversed this effect to control levels. Our results show that lipophilic statins can induce a pro-apoptotic state in human adult cardiac myocytes in vitro. We speculate that, similar to findings in animal models, statins might be involved in the attenuation of cardiac hypertrophy and remodeling in humans by modulating the balance between cell survival and apoptosis.