热疗联合阿霉素和TRAIL对肝癌HepG2细胞凋亡的影响

目的:观察热疗（hyperthermia,HT）联合亚浓度阿霉素(adriamycin,ADM)和肿瘤坏死因子相关凋亡诱导配体（tumor necrosis factor related apoptosis inducing ligand,TRAIL）对肝癌HepG2细胞凋亡的影响,以确定联合方案是否具有协同作用。方法:采用CCK8法检测细胞的活性;Hoechst 33258染色实验检测细胞的形态变化;流式细胞仪检测细胞的凋亡;Western blot实验检测细胞内蛋白的表达水平。结果:HT联合ADM和TRAIL可明显抑制肝癌HepG2细胞的活性（P＜0.05）,促进细胞染色质浓缩、核碎裂。流式细胞检测结果表明,HT联合ADM和TRAIL可促进细胞的早期凋亡（P＜0.001）和晚期凋亡（P＜0.01）。Western blot实验进一步证明,HT联合ADM和TRAIL通过上调DR4、DR5、caspase-3和caspase-8蛋白的表达来促进细胞的凋亡（P＜0.05）。结论:HT联合ADM和TRAIL具有协同作用,可明显增加细胞凋亡的敏感性,促进肝癌细胞的凋亡。     

TRAIL受体在肿瘤细胞系上的表达及意义

目的 检测TNF相关凋亡诱导配体（TRAIL）的受体，在来源于血液系统、肝脏、肺脏和大肠的8个肿瘤细胞系中的表达，并探讨其意义。方法 采用半定量RT－PCR，对TRAIL受体的表达进行半定量检测。结果 TRAIL凋亡通路中，能够诱导凋亡反应的死亡受体DR4和DR5，在所检测的肿瘤细胞系中都有表达，其中DR5在所有肿瘤细胞系中的表达水平均显著高于DR4（P＜0．05）。而能够竞争性与TRAIL诱导的凋亡反应的诱骗受体DcR1和DcR2，在所有的肿瘤细胞中都呈低水平表达或不表达。结论 DR5可能在TRAIL诱导凋亡的通路中发挥最重要的作用。TRAIL死亡受体和诱骗受体在肿瘤细胞系中的表达具有差异性，这种差异性可在一定程度上解释不同细胞对TRAIL诱导凋亡的敏感度。     

Lymphocyte apoptosis in acute respiratory syncytial virus bronchiolitis

Respiratory syncytial virus (RSV) infection may have an effect on the development of T cell memory responses. RSV bronchiolitis in infants is associated with a transient decline in circulating lymphocytes. We hypothesized that the mechanism underlying this lymphopenia is apoptosis. Blood was taken from 32 infants during primary RSV bronchiolitis and three months later. Using flow cytometry, we found that absolute numbers of both CD3+/CD4+ T-helper lymphocytes (P = 0.029) and CD3+/CD8+ cytotoxic lymphocytes (CTL) (P = 0.043) were significantly reduced during acute infection. Up-regulated expression both of Fas (P < 0.001) and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor (P < 0.001) was found during acute illness on both CD3+/CD4+ and CD3+/CD8+ lymphocytes, when compared with convalescent samples. Expression of Fas on CD4+ lymphocytes was inversely related to CD4+ number (P = 0.03). Plasma levels of soluble Fas ligand (P = 0.028) and caspase-1 (P = 0.037), determined by enzyme-linked immunosorbent assay, were increased during bronchiolitis. Plasma interleukin-18, a product of caspase-1 activity, was not raised. Taken together, these data suggest that in acute RSV infection, CD4+ helper lymphocytes and CD8+ cytotoxic lymphocytes are primed to undergo apoptosis. This is a mechanism through which lymphopenia may occur and T cell memory may be altered.     

Expression of TRAIL (TNF-related apoptosis-inducing ligand) and its receptors in normal colonic mucosa,adenomas, and carcinomas

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in tumour cell lines. Four membrane-bound receptors for TRAIL have been identified, two apoptosis-mediating receptors, DR4 and DR5, and two apoptosis-inhibiting receptors, DcR1 and DcR2. The aim of this study was to examine the role of TRAIL and its receptors in colorectal cancer development. The immunohistochemical expression and localization of TRAIL and its receptors were investigated in normal mucosa (n=10), adenomas (n=19), and carcinomas (n=21). Correlations between the expression of TRAIL and its receptors and the degree of apoptosis (assessed by M30 expression) and histopathological characteristics were explored. TRAIL and its receptors were expressed in normal mucosal epithelium. Expression of the receptors was seen in adenomas and carcinomas. TRAIL expression was lost in a subset of colorectal tumours, more frequently in carcinomas than in adenomas (p<0.05). DR4 and DR5 staining was stronger in neoplastic cells than in normal cells and was accompanied by a higher degree of apoptosis. No differences were found between tumour and normal cells regarding DcR1 and DcR2 expression. No correlations were found between TRAIL or TRAIL receptor expression and histopathological characteristics. In conclusion, marked changes were seen in the course of the adenoma-carcinoma sequence with respect to the expression of TRAIL and TRAIL receptors DR4 and DR5. The stronger expression of DR4 and DR5 in neoplastic cells than in normal cells, together with a higher degree of apoptosis, suggests a possible functional role for these receptors in apoptosis induction in neoplastic colorectal cells.     

抗人DR5单克隆抗体——mDRA-6与顺铂协同杀伤白血病细胞HL-60作用研究

目的：观察抗死亡受体5（Death receptor 5,DR5）单克隆抗体--mDRA-6与顺铂（DDP）对HL-60细胞的协同杀伤作用.方法：DR5蛋白免疫BALB/c小鼠,融合筛选抗DR5杂交瘤细胞,制备抗DR5单抗--mDRA-6;流式细胞术测定顺铂对HL-60细胞表面DR5表达及细胞凋亡率;荧光显微镜下观察mDRA-6与顺铂协同作用下HL-60细胞形态变化;MTT法测定不同浓度的顺铂与mDRA-6对HL-60细胞存活的影响;琼脂糖凝胶电泳检测mDRA-6与顺铂联合对HL-60细胞DNA片段化的影响.结果：顺铂可诱导HL-60细胞表面DR5表达增加,mDRA-6与顺铂联用致HL-60细胞出现染色质浓缩、断裂,细胞出芽,凋亡小体形成等细胞凋亡形态学变化;250 ng/ml的mDRA-6作用于HL-60细胞10小时,细胞凋亡率为16.61%;0.16 μg/ml的DDP作用于HL-60细胞10小时,细胞凋亡率为2.35%;二者联合作用后,HL-60细胞凋亡率增至57.10%;mDRA-6与DDP联合作用HL-60细胞,DNA琼脂糖凝胶电泳显示明显“梯形”条带.结论：抗DR5单抗--mDRA-6与DDP对HL-60细胞具有强大的协同杀伤作用.     

The role of activation-induced cell death in the differentiation of T-helper-cell subsets

Activation-induced cell death (AICD) has been demonstrated in T-cell hybridomas, immature thymocytes, and activated mature T cells. However, the molecular mechanisms of AICD and its physiological role in T-helper-cell differentiation remain uncertain. Recently, we have shown that Th1 and Th2 cells have distinct mechanisms of AICD. Our findings suggest that signaling from cytokines initiates the differentiation program, but that the selective action of death effectors determines the fate of differentiating T-helper cells, and thus, the ultimate balance between T-helper subpopulations. Among T cells, activation-induced expression of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is observed exclusively in Th2 clones and primary T-helper cells differentiated under Th2 conditions, while the expression of CD95L (Fas ligand) occurs mainly in Th1 cells. Furthermore, Th1 cells are more susceptible than Th2 cells to apoptosis induced through either TRAIL or CD95L, and radiolabeled Th1 cells can be induced into apoptosis via fratricide by both Th1 and Th2 cells, while Th2 cells are spared. The pan-caspase inhibitor, z-VAD, prevents AICD in Th1 cells, but not Th2 cells, indicating different mechanisms of AICD in each T-helper subtype. Antibody blockade of TRAIL and CD95L significantly boosts interferon-γ (IFN-γ) production in vitro. Also, young mice with mutant CD95 (MRL/MpJ-lpr/lpr) have a stronger Th1 response to ovalbumin immunization than do controls. We conclude that apoptosis mediated by CD95L and TRAIL is critical in the selective removal of differentiating T helper cells.     

ERK1/2-mediated Cytoplasmic Accumulation of hnRNPK Antagonizes TRAIL-induced Apoptosis through Upregulation of XIAP in H1299 Cells

Objective Tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) resistance greatly limits the clinical therapeutic efficacy of TRAIL. Elucidating the molecular mechanism underlying TRAIL resistance will be fundamental to resolving this problem. Methods Nuclear and cytoplasmic protein extraction and immunofluorescence(IF) assay were used to detect changes in heterogeneous nuclear ribonucleoprotein K(hn RNPK) localization in H1299 cells. The evaluation of cell apoptosis in cells transfected with GFP-hn RNPK, GFP-hn RNPK S284/353 A, or GFP-hn RNPK S284/353 D mutant was performed using cleaved caspase-3 antibody. The gene expression of XIAP was tested by quantitative RT-PCR. Results Previously, we reported that hn RNPK antagonized TRAIL-induced apoptosis through inhibition of PKC-mediated GSK3β phosphorylation. In this study, we further demonstrate that TRAIL treatment induces cytoplasmic accumulation of hn RNPK in H1299 cells. The hn RNPK localized in the cytoplasm has a higher capacity to antagonize TRAIL-induced apoptosis. Both ERK1/2 signaling inhibitor U0126 and ERK-phosphoacceptor-site mutant(GFP-hn RNPK S284/353A) diminish cytoplasmic accumulation of hn RNPK induced by TRAIL. Moreover, we show that XIAP is involved in hn RNPK-mediated TRAIL resistance in H1299 cells. Conclusion Taken together, these results give new insights into the understanding of the molecular mechanism associated with TRAIL resistance in lung adenocarcinoma.     

白藜芦醇通过下调HAX-1的表达提高耐药结直肠癌细胞对TRAIL的敏感性

目的: 探讨天然药物白藜芦醇是否能提高耐药结直肠癌细胞对TRAIL的敏感性并研究其机制。方法: 将TRAIL耐药HT29细胞(TR-HT29细胞)按对照组,白藜芦醇组,TRAIL组,白藜芦醇+TRAIL组及白藜芦醇+TRAIL+HAX-1质粒组进行分组后,CCK-8法检测TR-HT29的细胞活力,流式细胞术检测TR-HT29细胞的凋亡程度和线粒体膜电位,western blot实验检测TR-HT29细胞HAX-1的表达水平、细胞色素c的释放和caspase-3的活化。结果: TR-HT29细胞对TRAIL的半数有效浓度(IC50)(19.4±1.3 ng/ml)显著高于HT29细胞(1.8±0.2, P<0.05)。白藜芦醇处理可显著抑制TR-HT29细胞中HAX-1蛋白的表达水平。白藜芦醇+TRAIL组TR-HT29的细胞活力抑制率(53.6±4.4 %)和凋亡诱导率(39.4±2.9 %)显著高于TRAIL组的细胞活力抑制率(14.3±1.0 %, P<0.05)、凋亡诱导率(9.6±0.7 %, P<0.05)和白藜芦醇+TRAIL+HAX-1质粒组的细胞活力抑制率(19.9±1.5 %, P<0.05)、凋亡诱导率(13.8±1.1 %, P<0.05)。白藜芦醇+TRAIL组TR-HT29的线粒体膜电位显著低于TRAIL组和白藜芦醇+TRAIL+HAX-1质粒组。白藜芦醇+TRAIL组TR-HT29细胞色素c的释放和caspase-3的活化显著高于TRAIL组和白藜芦醇+TRAIL+HAX-1质粒组。结论: 白藜芦醇通过下调HAX-1的表达提高耐药结直肠癌细胞对TRAIL的敏感性。     

Targeting cell death signalling in cancer: minimising ‘Collateral damage'

Targeting apoptosis for the treatment of cancer has become an increasingly attractive strategy, with agents in development to trigger extrinsic apoptosis via TRAIL signalling, or to prevent the anti-apoptotic activity of BCL-2 proteins or inhibitor of apoptosis (IAP) proteins. Although the evasion of apoptosis is one of the hallmarks of cancer, many cancers have intact apoptotic signalling pathways, which if unblocked could efficiently kill cancerous cells. However, it is becoming increasing clear that without a detailed understanding of both apoptotic and non-apoptotic signalling, and the key proteins that regulate these pathways, there can be dose-limiting toxicity and adverse effects associated with their modulation. Here we review the main apoptotic pathways directly targeted for anti-cancer therapy and the unforeseen consequences of their modulation. Furthermore, we highlight the importance of an in-depth mechanistic understanding of both the apoptotic and non-apoptotic functions of those proteins under investigation as anti-cancer drug targets and outline some novel approaches to sensitise cancer cells to apoptosis, thereby improving the efficacy of existing therapies when used in combination with novel targeted agents.