维生素E琥珀酸酯诱导K562/ADM细胞凋亡过程中线粒体结构和功能的改变

目的：观察维生素E琥珀酸酯（vitamin E succinate，VES）诱导K562／ADM耐药细胞凋亡过程中线粒体形态及功能的改变。方法：采用annexin V／PI双标记法和透射电镜检测K562／ADM细胞凋亡；电镜观察凋亡细胞线粒体形态结构变化；流式细胞仪（FCM）检测线粒体跨膜电位（△ψm）和caspase-3活性变化；激光共聚焦显微镜分析细胞色素C（cytochrome c，Cyt c）的释放。结果：20μmol／L和40μmol／L VES处理K562／ADM细胞12～24h，annexin V／PI染色检测发现早期凋亡细胞明显增加，并呈现典型的凋亡形态改变。线粒体内外膜融合、缩小、碎片化，嵴减少且紊乱；线粒体△ψm降低，细胞质内Cytc释放增多；caspase-3活性显著增强。结论：VES可能通过改变线粒体的形态结构和稳定性，导致线粒体膜电位降低，Cytc释放，caspase-3激活而诱发K562／ADM耐药细胞凋亡。     

咔唑生物碱HY-1诱导K562细胞凋亡作用的研究

目的研究咔唑生物碱HY1对人慢性骨髓性红白血病K562细胞的增殖抑制和凋亡诱导作用,并探讨其作用机制。方法通过SRB法检测HY1对K562细胞体外增殖的影响;通过PI荧光染色法、罗丹明123染色法、AnnexinⅤPI染色法等流式细胞术和琼脂糖凝胶电泳法,观察HY1处理K562细胞后凋亡相关指标的变化;通过Westernblot检测凋亡相关蛋白的变化。结果HY1对K562细胞体外增殖的半数抑制浓度(IC50)为(29.05±0.90)μmol/L。随着HY1药物浓度的增加和作用时间的延长,SubG1期细胞明显增加,线粒体膜电位迅速下降,发生凋亡的细胞比例也显著增加,而且经琼脂糖凝胶电泳检测到了典型的DNALadder。Westernblot结果显示,细胞色素c(Cytc)表达明显增加;caspase9酶原被剪切,且活化程度呈时间依赖性;caspase3酶原及其作用底物PARP也发生了剪切;caspase8表达无明显变化。结论HY1能够以剂量时间依赖方式,通过线粒体激活途径,诱导K562细胞发生凋亡,并由此发挥其抗肿瘤活性。     

右旋柠檬烯诱导人白血病细胞凋亡作用机制的初步研究

目的:探讨右旋柠檬烯(d-limonene)诱导人白血病细胞凋亡的作用机制.方法:以人白血病细胞株K562和HL-60为研究对象,采用MTT法及锥虫蓝染色法检测d-limonene对细胞增殖的影响,Annexin V/PI双重染色法检测其对细胞凋亡的影响,Western印迹法检测线粒体凋亡途径相关蛋白的表达.结果:d-Limonene作用后K562、HL-60细胞凋亡率呈时间及剂量相关性增加;且处理组Bcl-2/Bax比值下降,细胞质中细胞色素c表达增高,caspase-9表达以及caspase-3分裂明显增高.结论:d-limonene能够诱导人白血病细胞凋亡,线粒体凋亡途径的激活可能是其凋亡诱导的主要机制.     

δ-生育三烯酚诱导人肝癌HepG2细胞凋亡的机制研究

目的:探讨δ-生育三烯酚诱导人肝癌HepG2细胞凋亡的作用机制.方法:应用MTT法检测δ-生育三烯酚对人肝癌HepG2细胞增殖的影响,应用高内涵活细胞成像系统检测δ-生育三烯酚对人肝癌HepG2细胞凋亡率、细胞周期以及线粒体膜电位的影响,Western印迹法检测δ-生育三烯酚对人肝癌HepG2细胞凋亡相关蛋白(如caspase-3、caspase-8、caspase-9、Bcl-2、Bax、tBid和cytochrome C)表达的影响.结果:δ-生育三烯酚呈浓度依赖性地抑制肝癌HepG2细胞生长并诱导其凋亡,其机制为δ-生育三烯酚降低线粒体膜电位,并诱导cytochrome C从线粒体释放到细胞质中,调控Bcl-2家族蛋白表达(如上调Bax及tBid蛋白的表达,下调Bcl-2蛋白的表达),继而引起caspase-3、caspase-8和caspase-9的活化,最终导致肝癌 HepG2细胞凋亡.结论:δ-生育三烯酚可能通过线粒体途径及膜死亡受体途径共同诱导人肝癌细胞 HepG2凋亡.     

小白菊内酯对胃癌BGC823细胞凋亡表型的影响

目的:探讨小白菊内酯对胃癌BGC823凋亡表型影响.方法:MTT法检测BGC823增殖能力的变化,同时在倒置显微镜下观察细胞形态;采用流式细胞仪检测细胞线粒体膜电位的变化; ELISA法检测caspase-3活性;western blot法检测细胞Bcl-2表达.结果:Par以浓度和时间依赖方式抑制胃癌细胞增殖,镜下可见细胞凋亡形态学改变 .经Par 处理后,随着Par浓度增加,细胞线粒体膜电位逐渐下降,经100μmol/L Par处理6h后,细胞caspase-3活性增加, 24h后下降, 至48h仍保持在高水平,western blot法检测到细胞Bcl-2表达下调.结论: Par通过下调Bcl-2和上调caspase-3活性来诱导细胞凋亡.     

1,4-苯醌致K562细胞线粒体功能障碍与凋亡作用

目的：研究1,4-苯醌对人慢性髓系白血病细胞（K562细胞）线粒体功能及凋亡的影响。方法：分别用终浓度为0、10、20 μmol/L的1,4-苯醌处理K562细胞24 h,用CCK-8法检测细胞活力,通过流式细胞仪检测活性氧（ROS）生成量;用线粒体膜电位、三磷酸腺苷（ATP） 生成量来评价线粒体功能;用PI-Annexin V双染法检测细胞的凋亡,采用分光光度法检测caspase-3酶的活性。结果：与对照组比较,1,4-苯醌10和20 μmol/L染毒组K562细胞相对增殖率均降低（P均<0.05）;随着1,4-苯醌浓度的增加,ROS生成量逐渐上升、线粒体膜电位和ATP生成量均逐渐降低、细胞的凋亡率逐渐增高,其中1,4-苯醌20 μmol/L染毒组与对照组间的差异均有统计学意义（P < 0.05或P < 0.01）;caspase-3活性逐渐升高,1,4-苯醌10和20 μmol/L染毒组与对照组相比差异均有统计学意义（P均<0.01）。结论：1,4-苯醌可以诱导K562细胞ROS升高,抑制K562细胞增殖,造成线粒体功能障碍,诱导细胞凋亡升高,提示线粒体障碍在1,4-苯醌诱导K562细胞凋亡的过程中发挥了重要作用。     

靶向激活蛋白激酶PKR诱导白血病K562细胞凋亡

目的: 采用双链RNA能激活细胞内蛋白激酶PKR引起细胞凋亡的策略,研究重组慢性粒细胞白血病独特的bcr/ab1 b3a2型外源反义RNA诱导白血病K562细胞的凋亡及其作用机制.方法: 用含bcr/abl融合基因序列40 bp的反转录病毒载体RV-40AS作用于白血病K562细胞,以光学显微镜、电子显微镜、FCM法和DNA梯状条带法检测细胞凋亡情况,化学比色法检测caspase-8和caspase-9活性变化,RT-PCR法检测Bax、Bcl-2 mRNA表达变化,并以Western印迹法检测双链RNA依赖性蛋白激酶(double-stranded RNA-dependent protein kinase,PKR)、磷酸化PKR(p-PKR)、Bax和Bcl-2的蛋白变化.结果: RV-40AS作用K562细胞组在光学显微镜下出现胞体皱缩、染色质浓集以及折光性减弱,电子显微镜下可见细胞质电子密度增大、核固缩和出现凋亡小体;FCM法检测到凋亡细胞占(22.70±1.42)%[未处理组(3.24±0.66)%],DNA电泳出现典型的梯状条带;caspase-8和caspase-9活性升高,PKR蛋白无明显变化,但p-PKR水平升高;Bax的mRNA和蛋白表达均升高,而Bcl-2mRNA和蛋白表达水平没有明显变化.对照组和PKR抑制剂处理组均未发生上述改变.结论: bcr/abl反义RNA反转录病毒载体RV-40AS可特异性激活PKR,从而诱导白血病K562细胞发生凋亡,其可能的机制是PKR活化激活了凋亡反应的上游分子caspase-8,并通过上调Bax表达水平、降低Bcl-2/Bax的比值,导致线粒体膜稳定性被破坏,促使凋亡小体形成和caspase-9活化,最终激活其他凋亡分子使细胞发生凋亡.     

过表达DACT1对白血病K562细胞生物学行为的影响及机制

目的:研究过表达DACT1对白血病K562细胞增殖、凋亡及细胞周期的影响,并探讨其作用机制。方法:用Attractene Transfection试剂在K562细胞中转染DACT1质粒,使其在细胞中过表达,应用CCK-8法、流式细胞术检测过表达DACT1对K562细胞增殖、凋亡及细胞周期的影响。Western blot法检测过表达DACT1后凋亡相关蛋白的变化。结果:过表达DACT1能够抑制K562细胞集落形成,抑制细胞增殖,促进细胞凋亡,使细胞发生G0/G1期阻滞。同时可使促凋亡蛋白Bax、caspase-3及caspase-9表达增加,抗凋亡蛋白Bcl-2表达减少。结论:过表达DACT1可以抑制白血病K562细胞增殖并诱导其凋亡,干扰其增殖周期,可能具有潜在的抑癌作用,其机制可能与调节凋亡相关蛋白有关。     

野生型p53基因蛋白在氨肽酶抑制剂诱导人白血病细胞株K562细胞凋亡的实验研究

目的研究野生型p53基因蛋白对国产氨肽酶抑制剂乌苯美司(ubenimex)诱导人白血病细胞凋亡的影响及其作用机制。方法真核转导试剂FuGEMNE^TM6转导入K562细胞，免疫组化法检测细胞p53蛋白的表达，DNA片段原位末端标记及流式细胞仪(FCM)检测细胞凋亡，Rhodamin(Rh)123染色后，FCM检测细胞线粒体跨膜电位。结果p53基因cDNA转导的细胞p53蛋白表达增加；p53基因转导能促进ubenimex诱导K562细胞凋亡并增加ubenimex诱导的K562细胞线粒体跨膜电位(△ψm)的下降。结论野生型p53基因转导能促进ubenimex诱导K562细胞凋亡，并可能参与线粒体信号传导通路的调控。     

苦瓜蛋白在K562/A02细胞生长抑制和凋亡中的作用及其机制研究

目的:研究苦瓜蛋白(momordin)诱导人慢性粒细胞白血病耐药细胞株K562/A02的凋亡及作用机制.方法:采用CCK-8法检测细胞生长抑制率,FCM法和细胞形态学检测细胞凋亡,FCM法检测P-糖蛋白(P-glycoprotein, P-gp)、p53、bcl-2和caspase-3蛋白表达水平,并运用caspase-8活性检测试剂盒检测caspase-8的活性.结果:苦瓜蛋白能抑制K562/A02耐药细胞的生长且呈剂量依赖关系,并能诱导细胞凋亡,能使P-gp、p53和bcl-2的表达下降,而使caspase-3和caspase-8活性增强.结论:苦瓜蛋白可逆转耐药细胞株K562/A02的细胞凋亡受抑性,主要机制可能与其下调p53、P-gp和bcl-2的表达以及提高caspase活性有关.     

Antitumor activity of total paeony glycoside against human chronic myelocytic leukemia K562 cell lines in vitro and in vivo

To explore the molecular mechanisms of human leukemia cells by total paeony glycoside (TPG), which is extracted from the root of Radix Paeoniae Rubra. The viability of K562 cells was assessed by MTT assay. Flow cytometry was used to detect apoptosis and cell cycle analysis. The changes in intracellular Ca²⁺ concentration were determined by fluorescent dye Fluo-3, and mitochondrial membrane potential was determined by the retention of the dye Rh123. The cytoplasmic Bax, Bcl-xL, and Bcl-2 protein expressions were determined by western blot. The mRNA expression of caspase-3, caspase-8, and caspase-9 was detected by RT-PCR. K562 cells were subcutaneously inoculated into nude mice to study the in vivo antitumor effects of TPG. The growth of K562 cells was inhibited and arrested in G0/G1 phase by TPG. TPG also caused apoptosis in K562 cells evidenced by cytosolic accumulation of cytochrome c, caspase-9, and caspase-3. TPG could down-regulate Bcl-2 and Bcl-xL and up-regulate Bax in K562 cells. TPG showed a significant decreased tumor volume and tumor weight in nude mice inoculated with K562 cells. TPG can be developed as a promising anti-chronic myeloid leukemia drug.     

Bax-induction alone is sufficient to activate apoptosis cascade in wild-type Bax-bearing K562 cells, and the initiation of apoptosis requires simultaneous caspase activation

It has been reported that expression of Bax by Tet-On system induces apoptosis in Jurkat cells. The parental Jurkat cells have mutation of Bax gene and do not express Bax protein. Wild-type Bax-bearing cells express endogenous Bax protein and it is still unclear whether overexpression of Bax alone can sufficiently induce apoptosis in these cells in the absence of any cytotoxic stimulus. To investigate this, wild-type Bax-bearing K562 cells were transfected with Tet-On Bax-inducible system (pTet-On and pTRE-Bax plasmids), and Bax-inducible stable cell lines were established. Overexpression of Bax in wild-type Bax-bearing K562 cells without any cyctotoxic signal resulted in increase of apoptotic cells, caspase-3 activation, mitochondrial release of cytochrome c, and mitochondrial membrane potential change. Western blotting and confocal microscopy revealed that overexpression of Bax was detected in mitochondria. A pancaspase inhibitor, zVAD-fmk, which has no effect on mitochondrial cytochrome c release and mitochondrial membrane potential change inhibited the apoptotic events in the presence of overexpressed Bax in mitochondria. These findings suggest that Bax protein, when present above a threshold level, is sufficient to trigger an apoptosis cascade, and its initiation requires simultaneous caspase activation probably not mediated by mitochondrial cytochrome c release and mitochondrial membrane potential change in K562 cells.     

Mechanism of beta 2-microglobulin-induced apoptosis in the K562 leukemia cell line,defective in major histocompatibility class 1

BACKGROUND: It has been shown that exogenous beta 2-microglobulin (beta 2m) triggers significant apoptosis in several cell lines, but the molecular mechanism of beta 2m-induced apoptosis remains to be found. MATERIALS AND METHODS: To understand the mechanism of beta 2m-induced apoptosis, we added purified human beta 2m to cultures of K562 human chronic myelocytic leukemia cells, detected apoptosis by DNA fragmentation and annexin V binding assays, measured mitochondrial membrane potential (delta psi m), and used Z-VAD-fmk, a general inhibitor of caspases, inhibitors of caspases-1 and-3, as well as Western blot analysis to detect activated caspases. RESULTS: beta 2m-induced apoptosis was associated with decreased delta psi m K562 cells. Treatment with the general caspase inhibitor Z-VAD-fmk, as well as the caspase-1 inhibitor YVAD-CHO, significantly blocked beta 2m-induced apoptosis. However, Western blot analysis revealed that caspase-1 was intrinsically activated in untreated as well as beta 2m-treated K562 cells. Furthermore, beta 2m-induced apoptosis was not associated with the cleavage of caspase-3 as revealed by Western blot analysis, but was inhibited by an inhibitor of caspase-3, Z-DEVD-CHO, suggesting that not caspase-3, but a caspase-3-like enzyme may be involved in beta 2m-induced apoptosis. Western blot analysis also revealed that caspases-4, -8 and -9 were not activated during beta 2m-induced apoptosis in these cells. CONCLUSION: These results reveal that beta 2m-induced apoptosis in K562 cells occurs by a mechanism dependent on decreased mitochondrial delta psi m. Moreover, while caspase-1 activity may be one of the factors involved in beta 2m-induced apoptosis, activation of this caspase alone does not cause apoptosis, and other proapoptotic factors including activation of a caspase-3-like enzyme, independently of caspases-4, -8 and -9 activity, may be required to trigger apoptosis.     

Induction of apoptosis by d-limonene is mediated by a caspase-dependent mitochondrial death pathway in human leukemia cells

Using K562 and HL60 cell lines, we have investigated the anti-tumoral activity of d-limonene, a monocyclic monoterpene, in human leukemia cells. Apoptosis was evaluated by Hoechst staining and by the annexin V/propidium iodide binding assay. d-Limonene induced apoptosis in a dose- and time-dependent manner in both cell lines. Our findings and data, demonstrating an increase in Bax protein expression, the release of cytochrome c from mitochondria, and an increase in caspase-9 and cleaved caspase-3, but not caspase-8, after the treatment of d-limonene, all suggest that the mitochondrial death pathway is primarily involved in the development of d-limonene-induced apoptosis.     

Unconjugated bilirubin induces apoptosis in colon cancer cells by triggering mitochondrial depolarization

Bilirubin is the principal end product of heme degradation. Prompted by epidemiologic analyses demonstrating an inverse correlation between serum bilirubin levels and cancer mortality, we examined the effect(s) of bilirubin on the growth and survival of colon adenocarcinoma cells. Adenocarcinoma cell monolayers were treated with bilirubin over a range of bilirubin:BSA molar ratios (0-0.6), and viability was assessed colorimetrically. Apoptosis was characterized by TUNEL assay, annexin V staining and caspase-3 activation. The mechanism(s) by which bilirubin induces apoptosis was investigated by Western blotting for cytochrome c release, assaying for caspase-8 and caspase-9 activation and for mitochondrial depolarization by JC-1 staining. The direct effect of bilirubin on the membrane potential of isolated mitochondria was evaluated using light-scattering and fluorescence techniques. Bilirubin decreased the viability of all colon cancer cell lines tested in a dose-dependent manner. Cells exhibited substantial apoptosis when exposed to bilirubin concentrations ranging 0-50 microM, as demonstrated by an 8- to 10-fold increase in TUNEL and annexin V staining and in caspase-3 activity. Bilirubin treatment evokes specific activation of caspase-9, enhances cytochrome c release into the cytoplasm and triggers the mitochondrial permeability transition in colon cancer monolayers. Additionally, bilirubin directly induces the depolarization of isolated rat liver mitochondria, an effect that is not inhibited by cyclosporin A. Bilirubin stimulates apoptosis of colon adenocarcinoma cells in vitro through activation of the mitochondrial pathway, apparently by directly dissipating mitochondrial membrane potential. As this effect is triggered at concentrations normally present in the intestinal lumen, we postulate a physiologic role for bilirubin in modulating colon tumorigenesis.     

Induction of apoptosis by casticin in cervical cancer cells through reactive oxygen species-mediated mitochondrial signaling pathways

Casticin, one of the main components from Fructus Viticis, has been reported to inhibit the growth of various cancer cells, including the human cervical cancer cell line HeLa. The purpose of this study was to examine the apoptotic activity and molecular mechanism of casticin action on human cervical cancer cells. The apoptotic activity of casticin on human cervical cancer HeLa, CasKi, SiHa and peripheral blood mononuclear cells (PBMCs) was measured using a histone/DNA ELISA assay, flow cytometry with propidium iodide (PI) staining and DNA agarose gel electrophoresis. The mitochondrial membrane potential and reactive oxygen species (ROS) production were evaluated by flow cytometry analysis. Caspase activities were assayed using a caspase colorimetric activity assay kit. Protein expression levels of cytochrome c, Bax, Bcl-2, Bcl-xL and XIAP were analyzed by Western blotting. Casticin caused accumulation of the Sub-G1 cells and increased reactive oxygen species (ROS) production in HeLa, CasKi, SiHa cell lines, but not in PBMCs. Apoptosis of HeLa cells was induced by casticin via mitochondrial release of cytochrome c due to the reduction of mitochondrial trans-membrane potential, activation of caspase-3 and -9, and the production of reactive oxygen species. The pan caspase inhibitor zVAD-FMK, the caspase-9 inhibitor zLEHD-fmk and N-acetylcysteine suppressed casticin-induced apoptosis. Bax was upregulated, while expression levels of Bcl-xL and XIAP were downregulated. However, there was no change in the expression of Bcl-2 under the same treatment. Our results indicate that casticin-induced apoptosis of cervical cancer cells is mediated by ROS generation and mitochondrial signaling pathways.     

A novel polysaccharide from Se-enriched Ganoderma lucidum induces apoptosis of human breast cancer cells

The novel polysaccharide SeGLP-2B-1 isolated from Se-enriched Ganoderma lucidum, showed anti-proliferative activity towards several cancer cell lines in vitro. To investigate the antitumor mechanisms, the apoptotic effects of SeGLP-2B-1 in human breast cancer cells were studied, and the mechanism of this action was further elucidated. Cell apoptosis was detected by Annexin V/PI staining. Caspase activity was assayed using a caspase apoptosis detection kit. Western blot analysis was used to evaluate the levels of pro-caspase-3, -8, -9, PARP and cytochrome c expression. The results showed that SeGLP-2B-1 inhibited the growth of MCF-7 cells in a time- and dose-dependent manner. Typical characteristics of apoptosis were observed, including morphological changes, sub-G1 cells and DNA ladder formation. Further analysis showed that SeGLP-2B-1 treatment disrupted the mitochondrial membrane potential followed by an increase in the cytochrome c cytosolic levels. Sequentially, SeGLP-2B-1 increased the activities of caspase-9, -3 and poly (ADP-ribose) polymerase in a time-dependent manner, however, no obvious activation of caspase-8 was observed. Caspase-9 and caspase-3 inhibitor prevented SeGLP-2B-1-induced apoptosis, and the activities of caspases-3, -9 were significantly up-regulated by SeGLP-2B-1. Our studies suggest that SeGLP-2B-1 induces apoptosis via a mitochondria-mediated pathway.