药物诱导的玉米根尖凋亡细胞表面电特性研究(英文)

细胞凋亡过程中细胞表面膜的电位很可能会发生改变。本文首次报导：应用细胞电泳技术（ｃｅｌｌ ｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ）对细胞毒素类药物放线菌酮（ｃｙｃｌｏｈｅｘｉｍｉｄｅ）、放线菌素 Ｄ（ａｃｔｉｎｏｍｙｃｉｎ Ｄ）和秋水仙碱（ｃｏｌｃｈｉｃｉｎｅ）等诱导的植物凋亡细胞与正常细胞之间电泳迁移率（ＥＰＭ）的差异进行了比较,对引起的膜电位变化进行了定量分析。实验以玉米根尖分生组织为材料,制备原生质体,经过适当剂量的药物处理（Ｆｉｇ．１－Ｂ）,在尽量减少细胞膜被破坏的情况下（Ｆｉｇ．２）,观察到：三种细胞毒素类药物的作用有所不同,被诱导的植物凋亡细胞的膜表面Ｚｅｔａ电位绝对值比正常细胞的高（Ｆｉｇ．１－Ａ）。本研究提示细胞电泳可对凋亡细胞表面膜电位的变化进行定量分析,为细胞凋亡的检测在方法上提供了新思路。     

Suppressing ROS-TFE3-dependent autophagy enhances ivermectin-induced apoptosis in human melanoma cells

Melanoma is an aggressive skin malignancy with a high mortality rate; however, successful treatment remains a clinical challenge. Ivermectin, a broad-spectrum antiparasitic drug, has recently been characterized as a potential anticancer agent due to its observed antitumor effects. However, the molecular mechanisms of ivermectin remain poorly understood. In the current study, we tested the involvement of autophagy in the ivermectin mechanism of action in human melanoma cells. We exposed SK-MEL-28 cells to different concentrations of ivermectin (2.5, 5, and 10 μM) for 24 hours. Here, ivermectin-induced apoptosis, as evidenced by the upregulation of cleaved poly (ADP-ribose) polymerase, BAX expression, and caspase-3 activity and downregulation of BCL-2 expression. In line with the apoptosis response, ivermectin triggered autophagy. Pharmacological or genetic inhibition of autophagy further sensitized SK-MEL-28 cells to ivermectin-induced apoptosis. Mechanistically, ivermectin-induced TFE3^(Ser321) dephosphorylation, activated TFE3 nuclear translocation and increased TFE3 reporter activity, which contributed to lysosomal biogenesis and the expression of autophagy-related genes, and subsequently, initiated autophagy in SK-MEL-28 cells. Moreover, N-acetyl-cysteine, an reactive oxygen species (ROS) scavenger, abrogated the effects of ivermectin on TFE3-dependent autophagy. Taken together, we demonstrated that ivermectin increases TFE3-dependent autophagy through ROS signaling pathways in human melanoma cells and that inhibiting autophagy enhances ivermectin-induced apoptosis in human melanoma cells.     

多聚ADP-核糖聚合酶抑制剂对高浓度锌损伤 PC12细胞的保护作用

探讨多聚ADP-核糖聚合酶(PARP)抑制剂3-氨基苯甲酰胺(3-AB)对400μmo1/L氯化锌损伤PC12细胞的保护作用及其对锌造成的细胞死亡类型的影响.应用MTT法,免疫细胞化学和Western印迹分别测定PC12细胞的存活率和PARP活性;用Hoechst 33342/PI荧光双染色、膜联蛋白V结合实验及DNA断裂分析等方法检测细胞死亡类型.结果表明在400μmol/L氯化锌的作用下,细胞存活率降至(22.7±4.6)%,PARP活性增强,坏死、凋亡和正常细胞百分比分别为(58.4±6.3)%、(18.0±5.6)%及(23.6±4.2)%;3-AB使细胞存活率提高至(76.9±4.7)%,PARP活性减弱,坏死细胞百分数降至(19.2±5.2)%,而正常和凋亡细胞百分数增加到(43.3±1.9)%和(37.5±6.5)%.实验证明,PARP参与了高浓度锌诱导的PC12细胞损伤,抑制PARP活性可提高细胞的存活率,而这种保护作用在于减少细胞的坏死而非凋亡.     

Transgelin Silencing Induces Different Processes in Different Breast Cancer Cell Lines

Transgelin is a protein reported to be a marker of several cancers. However, previous studies have shown both up‐ and down‐regulation of transgelin in tumors when compared with non‐tumor tissues and the mechanisms whereby transgelin may affect the development of cancer remain largely unknown. Transgelin is especially abundant in smooth muscle cells and is associated with actin stress fibers. These contractile structures participate in cell motility, adhesion, and the maintenance of cell morphology. Here, the role of transgelin in breast cancer is focused on. Initially, the effects of transgelin on cell migration of the breast cancer cell lines, BT 549 and PMC 42, is studied. Interestingly, transgelin silencing increased the migration of PMC 42 cells, but decreased the migration of BT 549 cells. To clarify these contradictory results, the changes in protein abundances after transgelin silencing in these two cell lines are analyzed using quantitative proteomics. The results confirmed the role of transgelin in the migration of BT 549 cells and suggest the involvement of transgelin in apoptosis and small molecule biochemistry in PMC 42 cells. The context‐dependent function of transgelin reflects the different molecular backgrounds of these cell lines, which differ in karyotypes, mutation statuses, and proteome profiles.     

rVvhA功能模序膜成孔的预测及细胞毒作用机制分析

利用生物信息学预测rVvhA的141-335位氨基酸片段有膜成孔模序。基因克隆表达得到95%以上纯度的rMpf,电子透射电镜观察其能够抑制Hela细胞生长且呈剂量依赖性,即0.8,1.6,2.4μg/mL rMpf作用8 h后,细胞和线粒体形态均发生凋亡和坏死改变,细胞内活性氧产生明显,线粒体膜电位下降,mPTP荧光检测膜通道孔活性增强。以上结果表明,rMpf具有诱导Hela细胞损伤的生物学活性,可通过改变膜通透性引起细胞凋亡。     

凋亡而不出现DNA梯形带一例

用普通琼脂糖凝胶电泳UVB照射后分别培养24、36小时的NIH3T3细胞DNA,均未出现梯形带,但从细胞形态上看,大部分细胞发生凋亡并出现凋亡小体。电泳UVB照射后培养24小时的昆明小鼠胸腺细胞DNA,出现典型的凋亡梯形带。说明细胞在发生凋亡时DNA并不总是从核小体之间断裂的,不能把DNA梯形带作为判断细胞凋亡的唯一标准。     

无花果果浆对肿瘤细胞增殖抑制和诱导凋亡作用

为了探讨无花果果浆(Fig fruit latex,FFL)对人肿瘤细胞的生长抑制作用及其机制,用无花果果浆处理体外培养的人肿瘤细胞,细胞增殖试验(MTT法)、克隆形成试验研究FFL对人肿瘤细胞的增殖抑制作用,Brdu掺人试验、吖啶橙/溴乙啶(AO/EB)染色、流式细胞术检测FFL对肿瘤细胞DNA合成、凋亡和细胞周期的影响.结果,用FFL处理后,肿瘤细胞增殖活性降低(P＜0.05),克隆形成下降(P＜0.05),Brdu标记指数降低(P＜0.05),吖啶橙染色凋亡细胞增多(P＜0.05);细胞周期分布改变,凋亡指数升高(P＜0.01),G0/G1期细胞数增加(P＜0.01),S期细胞数减少(P＜0.01),在一定剂量内对正常细胞无明显影响.试验结果提示,FFL对所试肿瘤细胞的增殖有显著地抑制作用,其作用机理可能与抑制肿瘤细胞DNA合成,诱导肿瘤细胞凋亡及细胞周期阻滞有关.     

Programmed cell death in neurotumour cells involves the generation of ceramide

Ceramide has been typically thought of as the membrane anchor for the carbohydrate in glycosphingolipids but many studies have suggested that it may cause apoptosis. Apoptosis or programmed cell death (PCD) is thought to be responsible for the death of one-half of neurons surviving the development of the nervous system. The potential involvement of the sphingomyelin-ceramide signaling process as an integral part of PCD was therefore examined in several neurotumour cell lines. We show that synthetic C2-ceramide (N-acetylsphingosine), a soluble ceramide analogue, can rapidly trigger PCD in these cells, characterized by: 1) classic DNA laddering on agarose gels; 2) DNA fragmentation as determined by Hoechst Dye; and 3) cell viability (mitochondrial function and intact nuclei) assays. We report that staurosporine can both activate PCD (by all three criteria above) in neurotumour cells and increase both the formation of ceramide and ceramide mass. Both ceramide formation and the induction of PCD were further enhanced by the co-addition of a ceramidase inhibitor oleoylethanolamine (25 µM). Staurosporine and oleoylethanolamine were similarly effective in inducing ceramide formation and PCD in immortalized hippocampal neurons (HN-2) and immortalized dorsal root ganglion cells (F-11). Our data suggests that formation of ceramide is a key event in the induction of PCD in neuronally derived neurotumour cells.Abbreviations PCD programmed cell death - PKC protein kinase C - HPTLC high-performance thin-layer chromatography - DETAPAC diethylenetriaminepentaacetic acid - DMEM Dubelco's modified Eagle's medium - FCS fetal calf serum - PBS phosphate-buffered saline - DAG diacylglycerol - DDI distilled-deionized - Cer ceramide - SM sphingomyelin Dedicated to Dr Sen-itiroh Hakomori in celebration of his 65th birthday.     

自由基与视网膜色素上皮作用研究进展

自由基是不配对的电子结构,具有极其活泼的化学特性,体内过剩的自由基可与细胞和生物大分子相互作用,从而引起机体的过氧化损伤。视网膜色素上皮处在高氧和光照环境中,其发挥生理功能时容易受氧化损伤。本文介绍了自由基的概念、自由基致视网膜色素上皮氧化损伤机制、一氧化氮自由基与视网膜色素上皮和抗氧化剂等方面的内容。