三氧化二砷诱导NB4细胞凋亡和环氧合酶-2基因表达研究

本研究探讨三氧化二砷(As2O3)诱导NB4细胞凋亡过程中线粒体膜电位的改变及环氧合酶-2的表达变化。利用免疫荧光显微镜、DNA电泳等观察As2O3诱导NB4细胞凋亡过程中NB4细胞的形态学改变,流式细胞术检测NB4细胞凋亡率及线粒体膜电位改变,Western blot分析环氧合酶-2的蛋白质表达水平变化。结果表明,经2μmol/L As2O3处理NB4细胞48小时后,荧光显微镜显示NB4细胞出现核致密浓染、染色质固缩及片断化断裂,甚至呈碎片状;提取DNA进行琼脂糖电泳显示典型DNA Ladder现象。流式细胞术分析发现,NB4细胞经3μmol/L As2O3处理48小时后细胞凋亡率为33.34%,As2O3浓度越高,NB4细胞凋亡率越高;以0.5、1、2、4及8μmol/L As2O3分别处理NB4细胞48小时后,线粒体膜电位分别下降12.8%、21.6%、66.9%、83.7%和83.8%;Western blot检测显示,环氧合酶-2在实验组的表达明显低于对照组,且随着As2O3浓度的升高,环氧合酶-2的表达逐渐降低,二者呈显著的负相关关系。结论 :As2O3能够有效诱导NB4细胞凋亡,且在一定浓度范围内具有量效关系;线粒体膜电位下降与As2O3诱导的NB4细胞凋亡有关;环氧合酶-2可能参与了As2O3诱导的NB4细胞凋亡过程。     

三氧化二砷抑制NB4细胞增殖机制的探讨

目的 通过检测NB4细胞活化JAK1蛋白水平探讨三氧化二砷(As2O3)对其增殖抑制的分子生物学机制.方法 利用Western blot检测NB4细胞JAK1蛋白表达及磷酸化水平;用小分子RNA(siRNA)干扰NB4细胞JAK1蛋白的表达及转染JAK1质粒使NB4细胞内JAK1过表达;应用MTF法及锥虫蓝拒染法观察在JAK1基因沉默或过表达的状态下,As2O3抑制NB4细胞增殖的变化情况;在此基础上利用Western blot方法进一步检测磷酸化JAK1蛋白(P-JAK1)及细胞周期抑制蛋白P21的变化.结果 NB4细胞内可检测到JAK1蛋白稳定表达,但未检测到其磷酸化;As2O3作用NB4细胞后,JAK1磷酸化水平增强;JAK1 siRNA转染NB4细胞后JAK1蛋白表达水平明显低于非特异性siRNA转染组(即lamin siRNA转染组)及空白对照组;且在JAK1 siRNA转染组As2O3抑制NB4细胞增殖作用减弱,4μmol/L As2O3对JAK1 siRNA转染组NB4细胞增殖抑制率为49.12%,较非特异性siRNA组(74.58%)及空白对照组(72.33%)明显下降;JAK1质粒转染NB4细胞后野生型及突变型JAK1质粒组较空质粒组JAK1蛋白表达水平显著升高,且在野生型JAK1质粒转染组,As2O3抑制NB4细胞增殖作用增强,4 μmol/L As2O3对野生型JAK1质粒转染组NB4细胞增殖抑制率为69.53%,较突变型JAK1质粒组(37.26%)及空质粒组(39.61%)明显升高;As2O3作用NB4细胞后P21蛋白的表达水平上调.结论 JAK1蛋白在NIM细胞内稳定表达但没有活性;As2O3通过激活JAK1蛋白抑制NB4细胞增殖;As2O3激活JAK1蛋白后通过上调P21的表达而抑制NB4细胞增殖.     

全反式维甲酸与三氧化二砷对NB4细胞CD44v6表达的调节

黏附分子CD44v6与急性髓系白血病(AML)疾病进展密切相关。本研究探讨全反式维甲酸(ATRA)及三氧化二砷(As2O3)对急性早幼粒细胞白血病细胞系NB4细胞CD44v6及其相关的PI3K/Akt信号通路的影响。应用显微镜观察检查和流式细胞术检测NB4细胞的分化;AnnexinⅤ-FITC/PI双染色流式细胞术检测NB4细胞凋亡;实时RT-PCR检测NB4细胞CD44v6 mRNA的表达;Western blot检测NB4细胞CD44v6蛋白的表达及PI3K/Akt信号通路的变化。结果显示:在ATRA诱导NB4细胞分化过程中,CD44v6的转录明显受抑制,但CD44v6蛋白表达无明显增减,PI3K/Akt信号通路被激活。在As2O3诱导NB4细胞凋亡过程中,CD44v6的转录水平及蛋白表达均明显下调,PI3K/Akt信号通路受抑。结论:ATRA与As2O3对NB4细胞CD44v6表达的影响不同。此研究结果为从干预白血病细胞和造血微环境相互关联角度进一步揭示ATRA和As2O3的作用机制奠定了实验基础。     

三氧化二砷对K562/ADM耐药细胞凋亡抑制的逆转作用

目的:研究三氧化二砷(As2O3)诱导白血病K562/ADM耐药细胞凋亡的分子机制。方法:采用MTT比色法检测K562/ADM耐药细胞增殖活性,细胞形态学和annexinV /PI双染色检测细胞凋亡,RT-PCR检测mdr1、bcl-2和caspase-3基因mRNA的表达水平,流式细胞法(FCM)测定P-糖蛋白(P -glycoprotein,P-gp)和bcl-2蛋白表达及caspase-3活性。结果:As2O3显著抑制K562/ADM耐药细胞的增殖;经 As2O3处理后细胞形态上出现典型的凋亡改变,annexinV /PI双染显示凋亡细胞明显增加;mdr1mRNA表达和P-gp合成明显降低,凋亡抑制基因bcl-2mRNA及其蛋白bcl-2表达下调, caspase-3mRNA表达和caspase-3活性显著增强。结论:As2O3诱导K562/ADM耐药细胞凋亡,其主要机制可能为As2O3抑制 mdr1和bcl-2基因表达,逆转耐药白血病细胞因bcl-2和P-gp高表达所介导的凋亡抑制。     

二甲基酰胺及环孢菌素A加强砷剂诱导早幼粒细胞白血病细胞系NB4凋亡

目的 观察线粒体膜通透性转运孔（MPT）的开放剂二甲基酰胺（diamide)和抑制剂环孢菌素A对三氧化二砷（As2O3)诱导的NB4细胞凋亡的影响。方法 用不同浓度的二甲基酰胺、环孢菌素A和As2O3单独或联合处理急性早幼粒细胞白血病（APL）细胞系NB4细胞。通过细胞形态学观察、基因且DNA电泳、Annexin-V含量及细胞DNA含量分布等鉴定细胞凋亡。应用流式细胞仪检测罗丹明123（Rh123)的染色强度测定线粒体跨膜电位（ΔΨm)。结果 二甲基酰胺和环孢菌素A均明显增加As2O3诱导的NB4细胞凋亡。同时，As2O3诱导的NB4细胞ΔΨm下降也因二甲基酰胺和环孢菌素A的联合处理而加强。在1μmol/L As2O3处理72h的NB4细胞，27．9％的细胞ΔΨm下降，而两者共同处理时，ΔΨm下降的细胞达59．7％和42．2％。结论 As2O3诱导的ΔΨm破坏可能涉及到组成MPT的重要分子，尤其是腺嘌呤转动蛋白相关分子的巯基氧化。     

三氧化二砷联合8-CPT-cAMP诱导维甲酸耐药早幼粒细胞白血病细胞分化的实验研究

目的 了解三氧化二砷（As2O3)联合8-对氯苯硫基环腺苷酸（8-CPT-cAMP)对维甲酸（RA）耐药、的急性早幼粒细胞白血病（APL）细胞的作用。方法 以RA耐药的APL细胞株NB4-R1和NB4-R2为模型。通过观察细胞生长，形态，表面分化抗原以及对四氮唑蓝的还原能力的改变来研究As2O3,8-CPT-cAMP单独和联合对细胞增殖及分化的影响；并应用免疫荧光和Western blot检测药物处理前后细胞内PML-RARα融合蛋白以及细胞周期调控蛋白的变化。结果 低剂量As2O3(0.25μmol/L）与8-CPT-cAMP(200μmol/L）可协同促进NB4-R1和NB4-R2细胞分化。8-CPT-cAMP可通过影响细胞周期调控蛋白E2F和P21的表达而抑制细胞增殖，并促进As2O3介导的PML-RARα融合蛋白降解。结论 As2O3联合8-CPT-cAMP能够诱导RA耐药的APL细胞分化。     

三氧化二砷诱导人骨髓瘤细胞RPMI8226发生Caspase非依赖性细胞凋亡的实验研究

本研究探讨三氧化二砷(As2O3)作用于骨髓瘤细胞RPMI8226引起非Caspase依赖性细胞凋亡。用MTT法检测细胞增殖率,流式细胞术检测RPMI8226细胞的凋亡率,Western blot方法检测细胞BCL-2及Caspase-3蛋白表达水平。结果表明,As2O3(0.1-20μmol/L)作用于人骨髓瘤细胞RPMI8226 24,48,72 h显示出明显的增殖抑制作用(P<0.05),呈浓度和时间依赖性。与As2O3(10μmol/L)单独处理组相比,zVAD-fmk(20μmol/L)与As2O3联合处理组的凋亡率未见明显变化。与As2O3(10μmol/L)单独处理组比较,zVAD-fmk与As2O3联合处理组Caspase-3、BCL-2蛋白表达明显升高。结论:As2O3对RPMI8226细胞的增殖有明显的抑制作用。As2O3可诱导RPMI8226细胞发生凋亡,其凋亡过程中可能存在Caspase非依赖性细胞凋亡程序。     

Bortezomib或联合三尖杉酯碱、三氧化二砷对急性髓系白血病原代细胞增殖作用的影响

目的:探讨bortezomib单独或联合三尖杉酯碱(HT)、三氧化二砷(As2O3)对初发及难治/复发急性白血病原代细胞的增殖作用。方法:以初发及难治/复发急性髓系白血病原代细胞为研究对象,分别应用bortezomib、HT、As2O3单独或联合处理细胞后,使用MTT法观察细胞增殖活力。结果:10～500nmol/L bortezomib对初发及难治/复发性白血病患者原代细胞均有抑制作用,且呈明显剂量依赖关系,随浓度增大抑制效果逐渐增强。作用于初发白血病原代细胞时,Bortezomib与HT联合与各单药处理组相比,抑制率无明显提高,而联合As2O3时其抑制率优于单药处理组;作用于难治/复发白血病原代细胞时,bortezomib与HT或As2O3联合效果均呈现相加作用,其中与As2O3联合效果优于与HT联合者。结论:Bortezomib能够抑制初发及难治/复发急性白血病原代细胞增殖,与As2O3联合作用后抑制效果明显增强。     

三氧化二砷对骨髓瘤细胞系U266抑制增殖及诱导凋亡的机制研究

本研究探讨三氧化二砷(As2O3)在体外对骨髓瘤细胞系U266的生物学效应及其机制。用MTT法观察As2O3对U266细胞增殖的影响,用流式细胞术、DNA凝胶电泳法分析As2O3对U266细胞凋亡的影响,以RT-PCR法检测2μmol/LAs2O3不同处理时间对U266细胞人端粒酶逆转录酶蛋白催化亚单位(hTERT)mRNA的表达变化,用Western blot法检测As2O3不同处理时间对U266细胞procaspase-3、bcl-2及hTERT蛋白水平的表达变化。结果表明:As2O3能明显抑制U266细胞增殖,半数抑制浓度(IC50)为2μmol/L;As2O3能诱导U266细胞凋亡,呈现剂量和时间依赖性;2μmol/L As2O3不同时间处理U266细胞后procaspase-3蛋白及hTERT mRNA、蛋白表达呈时间依赖性降低,而bcl-2蛋白表达未发生变化。结论:As2O3通过改变线粒体跨膜电位,触发了U266细胞的线粒体凋亡途径,导致了caspase-3的活化,最终诱导U266细胞凋亡;hTERT表达下调也是As2O3诱导U266细胞凋亡的重要作用机制。     

As2O3对NB4细胞蛋白酶体β1亚基的影响

本研究探讨As2O3对于NB4细胞蛋白酶体β1亚基的影响,以阐明As2O3在治疗急性早幼粒细胞白血病中的作用。以0．5μmol／LAs2O3干预NB4细胞,分别提取干预24小时及48小时后的总蛋白;以Westernblot检测蛋白酶体β1亚基及PML—RARα融合蛋白表达变化,并进行灰度分析。结果表明：经As2O3干预的NB4细胞中蛋白酶体β1亚基表达在As2O3干预24小时后明显升高,48小时后回落至基线水平。PML—RARα融合蛋白表达在干预24小时后明显降低,48小时后维持在明显低水平。结论：As2O3对于NB4细胞中蛋白酶体β1亚基有诱导上调作用,且与As2O3诱导NB4细胞PML—RARα融合蛋白降解及NB4细胞分化凋亡有一定的关系。     

p53-independent NOXA induction overcomes apoptotic resistance of malignant melanomas

Once melanoma metastasizes, no effective treatment modalities prolong survival in most patients. This notorious refractoriness to therapy challenges investigators to identify agents that overcome melanoma resistance to apoptosis. Whereas many survival pathways contribute to the death-defying phenotype in melanoma, a defect in apoptotic machinery previously highlighted inactivation of Apaf-1, an apoptosome component engaged after mitochondrial damage. During studies involving Notch signaling in melanoma, we observed a gamma-secretase tripeptide inhibitor (GSI; z-Leu-Leu-Nle-CHO), selected from a group of compounds originally used in Alzheimer's disease, induced apoptosis in nine of nine melanoma lines. GSI only induced G2-M growth arrest (but not killing) in five of five normal melanocyte cultures tested. Effective killing of melanoma cells by GSI involved new protein synthesis and a mitochondrial-based pathway mediated by up-regulation of BH3-only members (Bim and NOXA). p53 activation was not necessary for up-regulation of NOXA in melanoma cells. Blocking GSI-induced NOXA using an antisense (but not control) oligonucleotide significantly reduced the apoptotic response. GSI also killed melanoma cell lines with low Apaf-1 levels. We conclude that GSI is highly effective in killing melanoma cells while sparing normal melanocytes. Direct enhancement of BH3-only proteins executes an apoptotic program overcoming resistance of this lethal tumor. Identification of a p53-independent apoptotic pathway in melanoma cells, including cells with low Apaf-1, bypasses an impediment to current cytotoxic therapy and provides new targets for future therapeutic trials involving chemoresistant tumors.     

VSV Oncolysis in Combination With the BCL-2 Inhibitor Obatoclax Overcomes Apoptosis Resistance in Chronic Lymphocytic Leukemia

In chronic lymphocytic leukemia (CLL), overexpression of antiapoptotic B-cell leukemia/lymphoma 2 (BCL-2) family members contributes to leukemogenesis by interfering with apoptosis; BCL-2 expression also impairs vesicular stomatitis virus (VSV)-mediated oncolysis of primary CLL cells. In the effort to reverse resistance to VSV-mediated oncolysis, we combined VSV with obatoclax (GX15-070)—a small-molecule BCL-2 inhibitor currently in phase 2 clinical trials—and examined the molecular mechanisms governing the in vitro and in vivo antitumor efficiency of combining the two agents. In combination with VSV, obatoclax synergistically induced cell death in primary CLL samples and reduced tumor growth in severe combined immunodeficient (SCID) mice-bearing A20 lymphoma tumors. Mechanistically, the combination stimulated the mitochondrial apoptotic pathway, as reflected by caspase-3 and -9 cleavage, cytochrome c release and BAX translocation. Combination treatment triggered the release of BAX from BCL-2 and myeloid cell leukemia-1 (MCL-1) from BAK, whereas VSV infection induced NOXA expression and increased the formation of a novel BAX-NOXA heterodimer. Finally, NOXA was identified as an important inducer of VSV-obatoclax driven apoptosis via knockdown and overexpression of NOXA. These studies offer insight into the synergy between small-molecule BCL-2 inhibitors such as obatoclax and VSV as a combination strategy to overcome apoptosis resistance in CLL.     

三氧化二砷诱导套细胞淋巴瘤细胞株凋亡及机制研究

本研究旨在探讨三氧化二砷(ATO)诱导套细胞淋巴瘤(MCL)细胞株凋亡的效应及其机制。以不同浓度的ATO处理细胞,再通过MTT法检测细胞MCL细胞株(jeko-1,mino,JVM-2)增殖;用AnnexinⅤ-FITC/PI双染流式细胞术检测jeko-1细胞的凋亡;用DiOC6(3)染色流式细胞术检测jeko-1细胞的线粒体跨膜电位丢失;用Western blot检测细胞周期蛋白D1(cyclin D1)及凋亡相关蛋白MCL-1,BCL-2,PUMA,NOXA,cCaspase-3,cCaspase-9,cPARP在ATO处理前后的表达变化。结果表明:ATO抑制MCL细胞增殖,诱导MCL细胞凋亡,并且引起MCL细胞线粒体跨膜电位丢失,引起MCL-1,PUMA,cyclin D1蛋白表达水平降低,cPARP,cCaspase-3,cCaspase-9表达水平增加,不影响BCL-2,NOXA表达。结论:ATO能有效抑制MCL细胞增殖,诱导MCL细胞株凋亡,其中细胞凋亡的线粒体途径起着重要的作用。     

茶多酚联合顺铂对人卵巢癌细胞SKOV3生长的影响及机制

目的观察茶多酚(TP)、顺铂(DDP)及二者联合对人卵巢癌细胞SKOV3增殖及凋亡的影响,初步探讨二者联合对SKOV3细胞生长影响的机制。方法人卵巢癌细胞SKOV3经低毒剂量TP、DDP单独或联合作用后,MTT法检测细胞增殖情况,DAPI核染色法荧光显微镜观察细胞凋亡形态变化,AnnexinV-FITC双染流式细胞术分析细胞凋亡,Westernblot方法检测细胞中Akt及p-Akt的表达。结果低毒剂量TP单药组、DDP单药组与联合用药组对细胞的增殖抑制率分别为(11.47±2.07)%、(32.26±4.85)%、(52.62±3.23)%,联合用药组的细胞增殖抑制率明显高于DDP单药组,差异有统计学意义(P=0.000);荧光显微镜下可见低毒剂量TP单药组的细胞核形态及染色与阴性对照组无明显差异,联合用药组细胞核比DDP单药组着色更重,核浓缩、核碎裂现象更加明显,呈现典型的细胞凋亡征象;低毒剂量的TP对细胞的凋亡无明显影响,联合用药组的凋亡率明显高于DDP单药组,差异有统计学意义(P=0.000);各用药组细胞中总的Akt蛋白表达无明显变化,p-Akt蛋白表达降低,其中联合用药组细胞中p-Akt蛋白表达降低最明显,与对照组及单药组比较,差异均有统计学意义(P<0.001)。结论 TP与DDP联合后可显著增强DDP的抑制细胞增殖、促细胞凋亡效应,可能是通过抑制Akt蛋白的磷酸化来实现的。     

1082-39, an analogue of sorafenib,inhibited human cancer cell growth more potently than sorafenib

Purpose1082-39, an analogue of sorafenib, is a derivative of indazole diarylurea. We evaluated the activity of 1082-39 against human cancer cell growth. Its effects and mechanisms of action were then compared with those of sorafenib. The experiments were performed in human melanoma M21 cells.MethodsCell viability was estimated by using the colorimetric assay. Annexin V-FITC/PI staining assay was used to recognize the apoptotic cells. Further analysis of the mitochondria membrane potential (MMP) was performed by the JC-1 fluorescence probe staining. The levels of apoptotic proteins and kinases related to cancer proliferation were determined by western blotting assay.Results1082-39 possessed the activity against cancer cell proliferation with time- and dose-dependent manner. 1082-39 induced M21 cell to apoptosis, showing the increase of annexin V-FITC/PI staining cells, the MMP collapse and releasing cytochrome c from mitochondria. Western blotting analysis showed the activation of the mitochondria-mediated intrinsic pathway, showing the increase of cleaved caspase-9, cleaved caspase-3 and cleaved PARP. Statistical analysis suggested that 1082-39 possessed greater activities than sorafenib in the inhibition of M21 proliferation and induction of apoptosis. These effects of 1082-39 might arise from its activity of regulation the PI3K/Akt and Wnt/β-catenin signaling pathways.Conclusions1082-39 is a promising candidate compound which could develop as a potent anticancer agent.     

大鼠脑缺血模型的改进和脑缺血再灌流损伤诱发细胞凋亡的研究

目的改进动脉内置线阻断法建立的大鼠大脑中动脉（ＭＣＡ）局灶性脑缺血模型,并探讨脑缺血诱发细胞凋亡的时效和量效关系。方法以顶端细,后逐渐增粗的涂抹硅橡胶改进栓子,ＴＴＣ染色鉴定缺血效果;ＴＵＮＥＬ－ＡＰ法和ＨＥ染色观察凋亡发生和形态学改变。结果ＴＴＣ染色证实了大脑缺血灶的的稳定出现;用ＴＵＮＥＬ法发现,缺血３０ｍｉｎ再灌流６ｈ后,凋亡阳性细胞即明显增多,４８ｈ再灌流后阳性细胞数最多;缺血５ｍｉｎ再灌流４８ｈ缺血脑区的凋亡细胞主要位于纹状体,１５ｍｉｎ缺血组皮层也开始散见阳性细胞;随缺血时间延长,凋亡细胞主要出现在缺血区周边。结论脑缺血可选择性诱发神经细胞凋亡。     

正常人骨髓基质细胞对HL-60和HL-60/VCR 细胞凋亡易感性的影响

为了观察正常人骨髓成纤维样基质细胞系HFCL对白血病敏感细胞HL-60和多药耐药细胞HL-60／VCR凋亡易感性的影响，先建立HL-60或HL-60／VCR细胞与HFCL细胞共培养体系；采用瑞氏-吉姆萨染色和吖啶橙／溴化乙啶(AO／EB)染色，分别在光镜和荧光显微镜下进行形态学观察；TUNEL检测晚期凋亡细胞，流式细胞术检测细胞周期、凋亡峰和annexin V阳性的早期凋亡细胞；Western blot检测Bcl-2、活化的胱冬蛋白酶(caspase)-3蛋白和P糖蛋白(Pgp)的表达变化。结果表明，经topotecan(TPT)处理后的HL-60和HL-60／VCR细胞，在光镜和荧光显微镜下均有典型的凋亡细胞形态学改变，这些改变具有时间和剂量依赖性；annexin V染色后能检测到早期凋亡细胞；细胞周期显示：G1期细胞比例增高，S期减低，并有明显凋亡峰；TUNEL能检测到许多阳性细胞；同时出现活化的caspase-3，伴有Bcl-2的表达下调，但与HFCL细胞共培养后，经TPT处理的HL-60和HL-60／VCR细胞中早期和晚期凋亡细胞有所减少，凋亡峰减低，而且活化的Caspase-3表达减弱，Bcl-2蛋白表达上调，且以直接接触组为甚。结论：正常骨髓成纤维样基质细胞HFCL能轻度降低白血病HL-60和HL-60／VCR细胞对TPT的凋亡易感性，并有caspase-3和Bcl-2重要信号传导分子的参与。     

Asbestos causes apoptosis in alveolar epithelial cells: role of iron-induced free radicals

Asbestos causes asbestosis and malignancies by mechanisms that are not fully understood. Alveolar epithelial cell (AEC) injury by iron-induced reactive oxygen species (ROS) is one important mechanism. To determine whether asbestos causes apoptosis in AECs, we exposed WI-26 (human type I-like cells), A549 (human type II-like cells), and rat alveolar type II cells to amosite asbestos and assessed apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate-biotin nick end labeling (TUNEL) staining, nuclear morphology, annexin V staining, DNA nucleosome formation, and caspase 3 activation. In contrast to control medium and TiO2, amosite asbestos and H2O2 each caused AEC apoptosis. A role for iron-catalyzed ROS was suggested by the finding that asbestos-induced AEC apoptosis and caspase 3 activation were each attenuated by either an iron chelator (phytic acid and deferoxamine) or a.OH scavenger (dimethyl-thiourea, salicylate, and sodium benzoate) but not by iron-loaded phytic acid. To determine whether asbestos causes apoptosis in vivo, rats received a single intratracheal instillation of amosite (5 mg) or normal saline solution, and apoptosis in epithelial cells in the bronchoalveolar duct regions was assessed by TUNEL staining. One week after exposure, amosite asbestos caused a 3-fold increase in the percentage of apoptotic cells in the bronchoalveolar duct regions as compared with control (control, 2.1% +/- 0.35%; asbestos, 7.61% +/- 0.15%; n = 3). However, by 4 weeks the number of apoptotic cells was similar to control. We conclude that asbestos-induced pulmonary toxicity may partly be caused by apoptosis in the lung epithelium that is mediated by iron-catalyzed ROS and caspase 3 activation.     

RITA inhibits multiple myeloma cell growth through induction of p53-mediated caspase-dependent apoptosis and synergistically enhances nutlin-induced cytotoxic responses

Mutations or deletions of p53 are relatively rare in multiple myeloma (MM), at least in newly diagnosed patients. Thus, restoration of p53 tumor suppressor function in MM by blocking the inhibitory role of murine double minute 2 (MDM2) is a promising and applicable therapeutic strategy. RITA and nutlin are two new classes of small molecule MDM2 inhibitors that prevent the p53-MDM2 interaction. Earlier reports showed p53-dependent activity of RITA in solid tumors as well as in leukemias. We and others recently described nutlin-induced apoptosis in MM cells, but it remains unclear whether RITA exerts antimyeloma activity. Here, we found that RITA activates the p53 pathway and induces apoptosis in MM cell lines and primary MM samples, preferentially killing myeloma cells. The activation of p53 induced by RITA was mediated through modulation of multiple apoptotic regulatory proteins, including upregulation of a proapoptotic protein (NOXA), downregulation of an antiapoptotic protein, Mcl-1, and activation of caspases through extrinsic pathways. Moreover, a number of key p53-mediated apoptotic target genes were identified by gene expression profiling and further validated by quantitative real-time PCR. Importantly, the combination of RITA with nutlin displayed a strong synergism on growth inhibition with the combination index ranging from 0.56 to 0.82 in MM cells. Our data support further clinical evaluation of RITA as a potential novel therapeutic intervention in MM.     

毒胡萝卜素诱导K562细胞凋亡及其机制的实验研究

本研究旨在探讨毒胡萝卜素对K562细胞的凋亡诱导作用及其可能机制。采用荧光显微镜观察凋亡细胞的形态变化，annexin V—FITC／PI双染法FCM检测凋亡率的变化，Ca^2＋荧光指示剂Fura-2／AM法荧光分光光度计测定细胞内Ca^2＋浓度（[Ca^2＋]i）的改变，Rh123单染法FCM检测线粒体△ψm的变化，Western blot检测caspase-3，-7，-9，-12、细胞色素C和GRP78蛋白的改变。结果显示：4μmol／L毒胡萝卜素作用K562细胞48小时后，荧光显微镜观察到细胞呈典型的凋亡形态变化，早期凋亡细胞核染色质呈固缩状、圆珠状或斑块状；晚期凋亡细胞核染色质呈固缩状或斑块状。1、2、4、8μmol／L毒胡萝卜素作用K562细胞24和48小时后细胞凋亡率分别为7．51％、11．65％、23，22％、30．56％和12．85％、20.27％、31．5l％、44．16％，在一定范围内呈剂量和时间依赖性，与对照组比较，均有统计学意义（P〈0．05）。毒胡萝卜素诱导K562细胞[Ca^2＋]i升高以及线粒体△ψm下降，并均呈一定的浓度依赖性，与对照组比较，均有统计学意义（P〈0．05）。Western blot检测显示，毒胡萝卜素诱导K562细胞caspase-3，-7，-9，-12剪切活化、细胞色素C释放、GRP78表达上调。结论：毒胡萝卜素可诱导K562细胞发生内质网应激反应性凋亡，内质网是细胞内诱导凋亡的一个重要新场所；caspase-3，-7，-9，-12剪切和活化、线粒体△ψm破坏和细胞色素C释放是毒胡萝卜素诱导K562细胞凋亡的重要机制之一，线粒体参与内质网应激反应性凋亡途径并发挥重要作用。