线粒体在细胞凋亡机制中的作用

细胞凋亡过程中许多重要事件的发生都与线粒体密切相关，本文就线粒体形态、通透性转换孔、膜电位的改变。细胞色素C（Cyt C）的释放，mtDNA的损伤以及Bcl-2基因家族对凋亡的调控在细胞凋亡机制中的作用作一综述。     

声动力学疗法的研究进展

声动力学疗法 (ｓｏｎｏｄｙｎａｍｉｃｔｈｅｒａｐｙ ,ＳＤＴ )是近 10年在日本兴起的一种以超声为动力激活血卟啉 (ｈｅｍａｔｏｐｏｒｐｈｙｒｉｎ ,Ｈｐ)及其衍生物治疗癌症的新方法 ,它利用超声具有深部穿透并能聚焦于肿瘤局部的能力 ,化学激活相对无毒的声敏剂分子 ,产生氧自由基 ,有针对性地杀伤肿瘤细胞 ;加之超声装置简单 ,价格低廉 ,操作方便 ,可重复使用 ,因而ＳＤＴ被认为是一种很有推广前景的物理疗法 ,尤其对深部和中晚期癌症的治疗[1] 。一、ＳＤＴ的由来ＳＤＴ是在光动力学疗法 ( ｐｈｏｔｏｄｙｎａｍｉｃｔｈｅｒａｐｙ …     

Bid蛋白在内质网和线粒体相关的凋亡过程中的作用

目的 研究Bid蛋白在内质网和线粒体相关的凋亡过程中的作用。方法 以高三尖杉酯碱（HHT）诱导人骨髓增生异常综合征（MDS）细胞系MUTZ-1细胞凋亡，用流式细胞术检测细胞凋亡率，RT—PCR及Westernblot法检测线粒体和内质网凋亡途径的相关基因及蛋白表达，激光共聚焦显微镜观察用药前后钙离子浓度和线粒体膜电位的改变以及凋亡相关蛋白Bid的转位。结果 0．05μg／ml HHT作用后4h胞质内Ca^2＋浓度增高，12h达高峰，其后开始下降。HHT作用后线粒体膜电位持续下降。内质网应激相关因子基因及蛋白表达增强，12h达到高峰，其后开始下降。激光共聚焦显微镜观察发现Bid蛋白用药前位于内质网，用药12h后转位至线粒体。结论 HHT可以诱导MDS细胞凋亡，内质网和线粒体相关的凋亡途径在其中发挥了重要的作用，Bid蛋白可能是两种凋亡途径的交叉点。     

细胞凋亡与线粒体

早在1972年Kerr,Wyllie及Gum等就提出了细胞凋亡(apoptosis)的概念,但在其后的几年里,这一重要的细胞死亡类型并未引起人们足够的重视,仅从形态学、生物化学等方面进行了观察,初步确定了这种细胞主动死亡类型的存在.对细胞凋亡这一生物学现象的重视不过是近五六年的事情.细胞凋亡是细胞自主的程序化死亡过程(programmed cell death,PCD).它对于维持多细胞机体的完整性和自身稳态具有重要作用.     

线粒体和凋亡

凋亡是精确调节细胞数量,清除无用的或有害的细胞过程。本文阐述了凋亡有关的线粒体（Ｍｔ）特征性变化;如膜电位的降低;膜通透性的转变;细胞色素Ｃ、ＡＩＦ的释放;ＲＯＳ产物的增加以及ｄｃｌ－２家族的影响等等,说明Ｍｔ与调亡的发生密切相关。     

线粒体损伤在脓毒症大鼠心肌细胞凋亡中的作用

目的 探讨线粒体损伤在脓毒症大鼠心肌细胞凋亡中的作用及其可能机制.方法 72只SD大鼠随机(随机数字法)分为2组:(1)阴性对照组18只,腹腔注射无菌生理盐水;(2)脓毒症组,按大肠杆菌内毒素注射后6、12、24 h分为3个亚组,各18只.取心脏组织,光镜和电镜下观察组织病理学和超微结构的变化,TUNEL法原位检测心肌细胞凋亡并计算凋亡指数,免疫印迹法检测核转录因子-κB (NF-κB) p65的表达,黄嘌呤氧化酶法测定线粒体超氧化物歧化酶(SOD)活性,比色法检测线粒体还原型谷胱甘肽(GPx)活性,硫代巴比妥酸法测定线粒体脂质过氧化产物丙二醛(MDA)含量,OxyBlot TMas蛋白氧化检测试剂盒观察线粒体蛋白氧化.结果 脓毒症大鼠心肌有炎症细胞浸润,细胞水肿及空泡形成,并且在24 h最明显;心肌细胞凋亡指数和核蛋白NF-κB p65活化均显著增加(P＜0.05).脓毒症大鼠心肌线粒体损伤明显,至24 h病变最严重,线粒体膜破碎,线粒体嵴消失,大量空泡形成.脓毒症大鼠心肌线粒体抗氧化酶SOD和GPx活性显著下降(均P＜0.05),线粒体脂质过氧化和蛋白氧化均显著增加(均P＜0.05),并呈时间依赖性.结论 线粒体损伤在脓毒症心肌细胞凋亡中发挥重要作用,其作用机制可能与线粒体抗氧化物酶活性降低,活性氧产生过多和聚集有关.     

线粒体膜电位在高三尖杉酯碱诱导T-淋巴细胞白血病细胞Molt-3凋亡中的作用

目的 研究线粒体膜电位（Mitochondrial membrane potential,MMP)改变在高三尖杉酯碱（HHT）诱导的细胞凋亡中的作用。方法 用膜联蛋白V染色,流式细胞仪和共聚焦激光扫描显微镜等手段观察Bax、 细胞色素C等在HHT诱导T－淋巴细胞白血病细胞（Molt-3）凋亡过程中与线粒体膜电位的关系。结果 发现HHT诱导细胞早期凋亡的同时,Bax从胞浆易位至线粒体,线粒体膜电位下降,同时细胞色素C从线粒体膜释放到胞浆。结论 线粒体膜电位下降是HHT诱导T－淋巴细胞凋亡的重要环节。     

声动力学疗法与血管成形术后再狭窄

血管成形术是治疗血管闭塞性疾病的主要手段,但术后再狭窄的高发生率为其的应用带来了阻碍。现今虽有多种防治再狭窄的方法,但均有一定缺点。随着声动力学疗法的兴起,已有研究者开始对声动力学疗法在防治血管成形术后再狭窄的作用进行研究,本文就这一方面作一综述和探讨。     

5-氨基乙酰丙酸介导的光动力疗法诱导HL-60细胞线粒体介导的凋亡

本研究探讨5-氨基乙酰丙酸介导的光动力疗法(ALA-PDT)作用于白血病细胞株HL-60后线粒体膜电位改变及凋亡相关基因Bcl-2表达的变化。以白血病细胞株HL-60为实验模型,实验分为4组:对照组、单纯ALA组、单纯光照组及ALA+PDT组。采用阳离子脂质荧光探针JC-1检测线粒体跨膜电位,RT-PCR及实时定量PCR方法检测PDT前后Bcl-2基因表达变化。结果表明,ALA-PDT后线粒体膜电位出现快速下降,0 h时线粒体跨膜电位崩塌的细胞比例升高至(58.28±0.92)%,与对照组相比有显著差异(P<0.05)。随着时间延长,这种细胞比例逐步增多,而单纯ALA组和单纯光照组则无明显变化;ALA-PDT后2 h Bcl-2基因表达显著下降,4 h进一步下降达到谷底,24 h时仍呈低表达,并通过实时定量PCR进一步得到了证实。结论:ALA-PDT诱导的HL-60细胞凋亡过程与其影响线粒体跨膜电位有关,即通过影响线粒体功能促进细胞凋亡;ALA介导的光动力作用部分是通过在基因转录水平下调抗凋亡基因Bcl-2而促进凋亡的。     

阿糖胞苷诱导HL-60细胞凋亡时线粒体膜电位变化

为研究阿糖胞苷(Ara-C)诱导HL-60细胞凋亡时线粒体膜电位(△Ψm)的变化及相互关系,采用Rhodamine123染色及流式细胞术检测HL-60细胞线粒体膜电位变化;流式细胞仪、AO/EB染色检测HL-60细胞凋亡.结果显示Ara-C作用于HL-60细胞6小时时出现细胞线粒体膜电位下降,当Ara-C浓度为0.05 mg/ml作用6、12、24小时时HL-60细胞线粒体中Rhodamine123荧光强度分别为117.9±7.6,100.9±7.7,87.6±10.7,不同时间荧光强度差异有显著性(p＜0.05);当Ara-C浓度为0.1 mg/ml作用6、12、24小时时HL-60细胞线粒体中Rhodamine123荧光强度分别为111.9±10.1,86.6±9.2,68.4±12.2,不同时间差异有显著性(p＜0.05);不同浓度组在12、24小时时比较有显著性差异(p＜0.05).当Ara-C浓度为0.05 mg/ml作用6、12、24小时时HL-60细胞凋亡率分别为(41.2±3.0)%,(53.7±5.1)%,(65.8±2.6)%,不同时间差异有显著性(p＜0.01);当Ara-C浓度为0.1 mg/ml作用6、12、24小时时HL-60细胞凋亡率分别为(45.7±4.1)%,(58.2±4.3)%,(70.1±2.3)%,不同时间差异有显著性(p＜0.01);不同浓度Ara-C在相同时间凋亡率无差别.HL-60细胞线粒体膜电位变化与其凋亡率呈高度负相关,当Ara-C浓度为0.05 mg/ml时,r=-0.89,p＜0.01;当Ara-C浓度为0.1 mg/ml时,r=-0.76,p＜0.01.结论阿糖胞苷在诱导HL-60细胞凋亡时伴有线粒体膜电位下降,两者呈显著负相关.线粒体膜电位下降可能是阿糖胞苷诱导HL-60细胞凋亡的重要机制之一.     

Blocking the Glycolytic Pathway Sensitizes Breast Cancer to Sonodynamic Therapy

Inhibition of the increased aerobic glycolysis in cancer cells is a promising methodology for various malignant tumor therapies but is limited by systemic toxicity, at least in part. Recent studies suggest that dual restriction of glycolysis and mitochondrial function may overcome this issue. Sonodynamic therapy (SDT), a prospective therapeutic modality for cancers, has been reported to induce mitochondria-dependent cell damage. Here, we investigated the combined effect of SDT and 2-deoxyglucose (2DG), an anti-glycolytic agent, on breast cancer both in vitro and in vivo. In vitro, we found that, compared with a single treatment, SDT + 2DG co-treatment significantly decreased cell viability and increased cell apoptosis. Moreover, the generation of reactive oxygen species was enhanced and mitochondrial membrane potential (MMP) was reduced after SDT + 2DG co-treatment. Furthermore, the oxidative phosphorylation was also restrained after SDT + 2DG co-treatment, further to cause the blockage of ATP provision. In vivo, SDT + 2DG markedly reduced tumor volume and weight, consistent with the in vitro findings. Furthermore, toxicology tests concurrently indicated that the dosages of sinoporphyrin sodium and 2DG were comparatively tolerable. Generally, these results indicated that SDT + 2DG combination therapy may be an available, promising therapy for highly metastatic breast cancer.     

Sonodynamic Therapy Mediated by Emodin Induces the Oxidation of Microtubules to Facilitate the Sonodynamic Effect

In previous studies, sonodynamic therapy mediated by emodin (emodin-SDT) induced cytoskeletal filament disruption and apoptosis of THP-1-derived macrophages. In this research, we investigated the underlying mechanism. THP-1-derived macrophages were incubated with emodin and exposed to ultrasound irradiation. After emodin-SDT, we measured the production of reactive oxygen species (ROS) and analyzed the level of amino acid oxidation in microtubules, the cleavage of microtubules and the mitochondrial membrane potential (MMP). We found that intracellular emodin accumulated mainly on microtubules. After emodin-SDT, generation of ROS was evident. Analysis of the carbonyl content of proteins suggested oxidation of microtubules. Microtubules were disrupted after emodin-SDT, and the antioxidant N-acetyl-L-cysteine prevented this disruption. MMP decreased after emodin-SDT, and this effect could be prevented by N-acetyl-L-cysteine. We conclude that emodin-SDT induces the generation of ROS. The oxidation of microtubules leads to its cleavage and the subsequent decline in MMP.     

Involvement of Mitochondrial and Reactive Oxygen Species in the Sonodynamic Toxicity of Chlorin e6 in Human Leukemia K562 Cells

It is well accepted that sonodynamic therapy (SDT) exerts cytotoxicity and anti-tumor activity in many human tumors through the induction of cell apoptosis. The aim of the work described here was to study the effect of chlorin e6 (Ce6)-mediated SDT on human chronic myelogenous leukemia K562 cells. Our results indicate that Ce6-mediated SDT can suppress the viability of K562 cells. SDT caused apoptosis as analyzed by annexin V-phycoerythrin/7-amino-actinomycin D staining as well as cleavage of caspase 3 and the polypeptide poly(ADP-ribose) polymerase. After SDT exposure, loss of mitochondrial membrane potential, translocation of Bax from cytoplasm to mitochondria and activation of caspase 9 indicated that the mitochondrial-related apoptotic pathway might be activated. This process was accompanied by rapid generation of reactive oxygen species (ROS). Scavenging of ROS significantly blocked caspase-3 expression and the killing effect of SDT on K562 cells. Stress-activated protein kinases c-jun NH2-terminal kinase (JNK) and the p38 mitogen-activated protein kinase were activated after SDT treatment. Together, these findings indicate that Ce6-mediated SDT triggers mitochondria- and caspase-dependent apoptosis; oxidative injury may play a vital role in apoptotic signaling cascades.     

Ultrasound Dose Fractionation in Sonodynamic Therapy

Sonodynamic therapy (SDT) is a new modality in cancer therapy and it is based on preferential uptake and/or retention of a sonosensitizing drug in tumor tissues and subsequent activation of the drug by ultrasound. The dose fractionation effect in radiation therapy has been known for more than a century, but it is not reported in SDT so far. In this study, the in vivo antitumor effect of the simultaneous dual-frequency ultrasound (1 MHz and 150 kHz) at low-level intensity (cumulative I_SATA = 2.2W/cm²; total energy density 3960J/cm²; for 30 min sonication) in combination with the sonosensitizer of photofrin (PF) (sodium porfimer) was investigated in dose fractionation regime in a spontaneous murine model of breast adenocarcinoma in Balb/c mice. The tumor-bearing mice were divided into six groups (n = 8 to 10): Untreated groups included control and sham; experimental groups were treated with 5 mg/kg intravenous injection of PF alone, with combined PF and ultrasound for 30-min sonication in one fraction at 24 h after PF administration; with combined PF and ultrasound for 30 min sonicatin in three fraction at 18, 24 and 30 h after PF administration; and finally with combined PF and ultrasound for 30 min sonication in five fraction at 12, 18, 24, 30 and 36 h after PF administration. The tumor growth delay (TGD) parameters and the percent of apoptotic index AI (%) were measured in treated and untreated groups. The results show that the TGD parameters in treatment groups with combined drug and ultrasound fractionation mode were significantly different compared with other groups (p < 0.05). Also the sonodynamic ultrasound dose fractionation in five fractions is more effective than of the three-fraction regime. The AI of the tumor tissues treated by ultrasound dose fractionation was also significantly higher in the other groups (p < 0.05), in which the AI (%) in the group treated with five fractions was higher with respect to group treated with 3 fractions (11.56 ± 1.2; 8.7 ± 0.87), respectively. In conclusion, the ultrasound dose fractionation can be useful in therapeutic effect in SDT and may have future clinical applications. (E-mail: ah_barati@yahoo.com)     

Sonodynamically Induced Apoptosis by Protoporphyrin IX on Hepatoma-22 cells In Vitro

The synergistic effect of ultrasound and certain chemicals on cells is known as sonodynamic therapy (SDT). It has been reported that the direct sonochemical and subsequent redox reactions induced by SDT treatment can lead to apoptotic cell death. However, the detailed biologic mechanism about it is not well understood until now. In this study the effect of low-intensity ultrasound on Hepatoma-22 cells (H22) in the presence of the sonosensitizing drug protoporphyrin IX (PpIX) was evaluated at different incubation times after sonication. Trypan blue exclusion was used to detect cell viability. The presence of apoptotic cells was identified by 4'-6-diamidino-2-phenylindole (DAPI) nuclear staining and transmission electric microscope (TEM) observation. An inverted confocal laser scanning microscope was used to detect the release of mitochondrial protein cytochrome c (Cyt c) and the redistribution of Bcl-2 family proteins Bid and Bax. Additionally, the generation of intracellular reactive oxygen species (ROS) and the loss of mitochondria membrane potential (MMP) were quantificationally measured by a fluorescence microplate reader. The results indicated that the synergistic cytotoxicity of PpIX and ultrasound increased in a time-dependent manner and the mitochondria damage may be the main factor for sonodynamically induced apoptosis by PpIX in H22 cells. (E-mail: lshaof@snnu.edu.cn)     

Role of autophagy in sonodynamic therapy-induced cytotoxicity in S180 cells

Few reports have been published on the potential role of autophagy in the efficacy of sonodynamic therapy (SDT). This study was to determine whether autophagy occurred after SDT and to investigate its relationship with apoptosis by performing inhibitor studies. In vitro murine sarcoma 180 (S180) cells were examined at different time points following SDT. Transmission electron microscopy (TEM) was used to identify the formation of autophagosomes. Western blots were used to assess the processing of LC3-I to LC3-II. Confocal microscopy was performed to reveal co-localization between mitochondria and autophagic vacuoles and re-distribution of apoptosis related proteins after sono-damage. Inhibitors of apoptosis and autophagy were used to determine the contributions of the two cellular responses to SDT efficacy. Autophagy was indentified by TEM observation of the presence of double-membrane delineated autophagic vesicles and by immunoblot observation of the increased LC3-II levels. The autophagy inhibitors, both 3-methyladenine (3-MA) and Bafilomycin A1 (Ba A1), were found to significantly enhance SDT-induced cell death. Blocking autophagy also led to increased dissipation of mitochondria potential, caspase-3 activity and the ultimate cell apoptosis. Whereas the pan-caspase inhibitor, z-VAD-fmk partially prevented SDT-induced cytotoxicity but did not obviously improve the autophagic vacuolization and mitochondria depolarization. This study suggests for the first time that autophagy participate in SDT-induced cell death and combination of SDT with autophagy inhibitors, especially preventing autophagy at the early stage by 3-MA, can significantly enhance the anti-tumor effect of SDT through induction of apoptosis and necrosis.     

Efficacy of Indocyanine Green-Mediated Sonodynamic Therapy on Rheumatoid Arthritis Fibroblast-like Synoviocytes

Sonodynamic therapy (SDT) has become a new therapeutic method because of its activation of certain sensitizers by ultrasound. Some studies have reported that indocyanine green (ICG) has the characteristics of a sonosensitizer and favorable fluorescence imaging in synovitis of early inflammatory arthritis. In this study, we aimed to investigate the cytotoxic effect of ICG-mediated SDT on MH7A cells in vitro and the potential mechanisms involved. ICG was found to be taken up mainly in cytoplasm, with maximal uptake in 4 h. Cell viability in ICG-mediated SDT (SDT-0.5 and SDT-1.0) groups decreased significantly to 73.09 ± 1.97% and 54.24 ± 4.66%, respectively; cell apoptosis increased significantly to 26.43 ± 0.91% and 45.93 ± 6.17%, respectively. Moreover, marked loss in mitochondrial membrane potential and greatly increased generation of reactive oxygen species were observed in ICG-mediated SDT groups. Interestingly, the loss in cell viability could be effectively rescued with pretreatment with the reactive oxygen species scavenger N-acetylcysteine. These results indicate that ICG-mediated SDT is cytotoxic to fibroblast-like synoviocytes and is a potential modality for targeted therapy of synovitis in rheumatoid arthritis.     

Sonodynamically Induced Anti-tumor Effect of 5-Aminolevulinic Acid on Pancreatic Cancer Cells

Sonodynamic therapy (SDT), a promising modality for cancer treatment, involves the synergistic interaction of ultrasound and some chemical compounds termed sonosensitizers. However, its effect on pancreatic cancer cells remains unclear. In our study, we sought to identify the cytotoxic effects of ultrasound-activated 5-aminolevulinic acid on human pancreatic cancer Capan-1 cells. Cell viability was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) analysis; mitochondrial membrane potential was assessed using the fluorescent probe jc-1; apoptosis was evaluated by flow cytometry; cell morphology was investigated by scanning electron microscopy; apoptosis-related protein expression was analyzed by Western blot assay. We found that SDT significantly decreased the survival rate of cells, and this effect increased with 5-aminolevulinic acid concentration and ultrasound exposure time. The mechanism underlying the effect of SDT involves, in part, the induction of a conspicuous loss in mitochondrial membrane potential and, in part, the induction of apoptosis through upregulation of Bax expression, downregulation of Bcl-2 and increased activation of procaspase-3. These results indicate that the ultrasonically induced cell killing effect could be enhanced by 5-ALA and that the mitochondrial pathway might be involved in the cell damage process. We conclude that SDT is a promising new methodology for pancreatic cancer treatment.     

Combination of Protoporphyrin IX-mediated Sonodynamic Treatment with Doxorubicin Synergistically Induced Apoptotic Cell Death of a Multidrug-Resistant Leukemia K562/DOX Cell Line

The main objective of this study was to evaluate the efficacy of administration of doxorubicin (DOX) in combination with protoporphyrin IX (PpIX)-assisted low-level therapeutic ultrasound (US) in K562/DOX cells as a potential strategy in cancer therapy. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to determine the cytotoxicity of different treatments. Apoptosis was analyzed using annexin V-PE/7-amino-actinomycin D staining. Changes in DNA fragmentation, intracellular reactive oxygen species production, cellular membrane permeability, P-glycoprotein expression and DOX uptake were analyzed with flow cytometry. Under optimal conditions, PpIX-US significantly aggravated DOX-induced K562/DOX cell death, compared with either monotherapy. Synergistic potentiation of DNA damage, generation of reactive oxygen species and P-glycoprotein inhibition were observed. Plasma membrane integrity changed slightly after US exposure, and DOX uptake was notably improved after PpIX-US exposure. The results indicate that PpIX-US could increase the susceptibility of tumors to antineoplastic drugs, suggesting a clinical potential method for sonodynamic therapy-mediated tumor chemotherapy.     

Induction of Sonodynamic Effect with Protoporphyrin IX on Isolate Hepatoma-22 Cells

Sonodynamic therapy (SDT) is a potential cancer therapy based on the synergistic interactions of ultrasound and certain chemical compounds (sono-sensitizers). It has become evident that the direct sonochemical and subsequent redox reactions induced by SDT treatment can lead to apoptotic cell death. However, the detailed mechanisms are not well understood. This study sought to identify the cytotoxic effects of ultrasound-activated protoporphyrin IX (PpIX) on Hepatoma-22 cells (H22). The fluorescence microscope was used to detect the generation of mitochondrial reactive oxygen species (ROS), mitochondrial swelling and release of mitochondrial protein cytochrome c. Several distinct sonochemical effects were found after SDT treatment, including changes of cell viability (decreased to 82.6% in SDT-treated group), generation of mitochondrial ROS, mitochondrial swelling and release of cytochrome c (19.16% in SDT-treated group). These results indicated that the ultrasonically-induced cell killing effect could be enhanced by PpIX, and that the mitochondrial pathway might be involved in the cell damage process. (E-mail: lshaof@snnu.edu.cn)