TRAIL蛋白原核表达载体的构建及表达研究

目的 利用蛋白自剪切功能原核表达系统构建肿瘤坏死因子相关凋亡诱导配体（TRAIL）胞膜外段融合蛋白表达载体,并进行表达条件优化和初步纯化。方法 设计基因拼接引物,合成TRAIL基因胞膜外段双链cDNA序列,将其连接于克隆载体pMD18-T中;将酶切、纯化的TRAIL基因与经相同处理的载体pTWIN1相连接,转化感受态大肠杆菌JM109,筛选阳性重组子。将鉴定（酶切及序列分析）阳性的重组子质粒转人大肠埃希菌ER2566表达菌中,采用蛋白质SDS—PAGE电泳方法分析不同浓度诱导剂异丙基硫代-β-D-半乳糖苷（IPTG）、不同诱导温度、不同诱导时间下目的蛋白表达情况。结果 成功获得了包含TRAIL基因胞膜外段的双链cDNA序列,酶切及序列分析证实成功构建了TRAIL胞膜外段蛋白自剪切功能原核表达载体。采用0．3mmol／LIPTG、15℃诱导过夜（14～16h）,目的蛋白获得较高表达量,且大部分为可溶性蛋白。结论 采用大肠埃希氏菌ER2566,TRAIL胞膜外段融合蛋白获得高表达,经简单后续处理即可获得不含任何额外氨基酸的可溶性目的蛋白。     

Novel engineered TRAIL-based chimeric protein strongly inhibits tumor growth and bypasses TRAIL resistance

Targeting of the TRAIL-DR4/5 pathway was proposed as a promising approach for specific induction of apoptosis in cancer cells. Clinical trials, however, showed inadequate efficiency of TRAIL as a monotherapy. It is a widely held view that the application of multifunctional molecules or combination therapy may lead to substantial improvement. Here, we demonstrate the effectiveness and safety of a novel chimeric protein, AD-O51.4, which is a TRAIL equipped with positively charged VEGFA-derived effector peptides. The study was performed in multiple cancer cell line- and patient-derived xenografts. A pharmacokinetic profile was established in monkeys. AD-O51.4 strongly inhibits tumor growth, even leading to complete long-term tumor remission. Neither mice nor monkeys treated with AD-O51.4 demonstrate symptoms of drug toxicity. AD-O51.4 exhibits a satisfactory half-life in plasma and accumulates preferentially in tumors. The cellular mechanism of AD-O51.4 activity involves both cytotoxic effects in tumor cells and antiangiogenic effects on the endothelium. The presence of DRs in cancer cells is crucial for AD-O51.4-driven apoptosis execution. The TRAIL component of the fusion molecule serves as an apoptosis inducer and a cellular anchor for the effector peptides in TRAIL-sensitive and TRAIL-resistant cancer cells, respectively. The FADD-dependent pathway, however, seems to be not indispensable in death signal transduction; thus, AD-O51.4 is capable of bypassing the refractoriness of TRAIL. AD-O51.4-driven cell death, which exceeds TRAIL activity, is achieved due to the N-terminally fused polypeptide, containing VEGFA-derived effector peptides. The high anticancer efficiency of AD-O51.4 combined with its safety has led to the entry of AD-O51.4 into toxicological studies.     

绒毛中TRAIL及其受体的表达与不明原因反复自然流产的相关性的探讨

目的探讨肿瘤坏死因子相关凋亡诱导配体TRAIL及其受体在不明原因早期反复自然流产患者(URSA)绒毛中的表达及二者的相关性。方法选择实验组妊娠45～60 d的URSA患者15例,对照组健康人工流产15例。两组分别取绒毛组织采用免疫组化法检测TRAIL及其受体的表达,进行方差分析和t检验比较两组绒毛组织中TRAIL及其受体蛋白表达水平的差异。结果实验组绒毛组织中TRAIL及其受体DR4、DR5蛋白表达较强,而诱骗受体DcR1及DcR2蛋白与正常对照相比表达较少,P值均小于0.05。结论TRAIL及其受体可能是造成自然流产的机制之一。     

TRAIL在原发免疫性血小板减少症患者外周血单个核细胞中的表达及临床意义

目的：探讨原发免疫性血小板减少症（primary immune thrombocytopenia,ITP）中TRAIL的表达及其在发病机制中的作用。方法使用Ficoll密度梯度离心法,收集28例ITP患者和30例健康对照的外周血单个核细胞（PBMC）。采用实时荧光定量PCR检测TRAIL基因的表达,采用 ELISA方法检测血清中细胞因子TNF-α,IFN-γ,IL-4和 IL-10的量,并分析TRAIL与患者TNF-α,INF-γ,IL-10和血小板计数的相关性。结果与健康对照组相比,ITP患者 PBMC中 TRAIL表达显著增高（2.80±0.43 vs 1.00±0.24,t＝19.72,P＜0.001）。与健康对照组相比,ITP患者血清中IFN-γ和TNF-α升高（52.43±11.04 pg/ml vs 23.26±8.15 pg/ml;69.14±10.89 pg/ml vs 36.14±13.17 pg/ml,t＝10.36～11.50,P值均＜0.001）,IL-10降低（11.18±6.13 pg/ml vs 33.28±9.85 pg/ml,t＝10.17,P＜0.001）,IL-4的变化差异无统计学意义（35.75±12.52 pg/ml vs 40.16±14.26 pg/ml,t＝1.25,P＞0.05）。且ITP患者TRAIL的表达与血清中IFN-γ,TNF-α正相关（r＝0.432,0.541,P 值均＜0.05）,与 IL-10,血小板计数负相关（r＝-0.424,-0.553,P 值均＜0.05）。结论TRAIL可能通过介导细胞因子免疫紊乱,参与了 ITP的发生与发展,这为进一步研究 ITP的免疫干预治疗提供了新的线索和思路。     

膀胱癌中DR4和DR5的表达水平与患者术后化疗及患者预后的关系

目的：在临床前期实验中,肿瘤坏死因子相关凋亡诱导配体（TRAIL）与化疗药物在抗癌中存在协同作用。表阿霉素广泛应用于膀胱癌的辅助化疗中。在这里,我们假设膀胱癌中死亡受体 DR4和 DR5表达水平与膀胱癌患者的术后化疗及预后相关。方法采用免疫组化法检测229例经尿道切除术后的膀胱癌患者及癌旁正常组织中的DR4和DR5的表达。结果膀胱癌患者细胞质中 DR4和 DR5的表达率分别为75.1％和74．2％。DR4与 DR5均高表达的患者术后10年随访期间的无复发生存率明显好于低表达者。多变量分析显示 DR4（P＜0．001）、DR5（P＜0．001）的表达及表阿霉素的治疗（P＝0．034）是膀胱癌患者预后的独立指标,而且表阿霉素治疗能够明显提高DR4（P＝0．006）或DR5（P＝0．042）高表达的膀胱癌患者的无复发生存率。结论 DR4和DR5均高表达的患者可能更适合接受表阿霉素治疗。     

顺铂在TRAIL/APO-2L致胶质瘤细胞凋亡作用中影响机制的研究

目的探讨TRAIL对胶质瘤细胞凋亡的影响,并进一步研究DNA破坏药物顺铂(CDDP)在与其联合作用诱导细胞凋亡中影响作用的机制。方法行人脑胶质瘤U251细胞株的培养,应用不同浓度TRAIL和CDDP作用于胶质瘤U251细胞,MTT法检测TRAIL和CDDP分别及联合作用于U251细胞后的存活率,并以亚毒剂量的TRAIL和CDDP联合作用后,流式细胞仪检测其凋亡率。Westernblot方法检测CDDP作用前后TRAIL受体DR5表达量的变化。结果MTT结果:在一定时间范围内,随着药物浓度增加,TRAIL和CDDP分别及联合作用皆使胶质瘤U251细胞存活率逐渐降低,其中两者的联合作用效果明显,与分别作用组差异有统计学意义(P<0.01)。亚毒剂量的TRAIL(50ng·ml-1)、CDDP(4μg·ml-1)分别及联合作用人脑胶质瘤U251细胞24h后,存活率分别为:72.43%,75.56%,23.45%。亚毒剂量的TRAIL(50ng·ml-1)、CDDP(4μg·ml-1)单独或联合作用组致胶质瘤细胞凋亡率分别为25.61%、20.59%、62.33%。单独应用组与联合组之间差异有统计学意义(P<0.01)。Westernblot法检测显示:CDDP作用后较作用前DR5表达有明显增高,随CDDP剂量增多,DR5表达量逐渐增加。结论TRAIL和CDDP联合作用能显著增强其对人U251胶质瘤细胞凋亡的诱导,其机制可能与CDDP能上调TRAIL死亡受体DR5的表达有关。     

白细胞介素12通过抑制survivin表达加强肿瘤坏死因子相关凋亡诱导配体诱导的肝癌细胞凋亡

目的 探讨肿瘤坏死因子相关凋亡诱导配体(TRAIL)对肝细胞癌(HCC)的治疗作用,以及TRAIL耐药的可能机制和逆转耐药方案。方法 采用原位杂交方法观察HCC与正常肝组织中TRAIL的表达差异。采用不同浓度的sTRAIL(可溶性)处理HCC细胞株及真核表达质粒pIRES-EGFP-sTRAIL转染HCC细胞株,观察sTRAIL的抑癌疗效。建立裸鼠肝癌模型,观察sTRAIL的体内抑癌作用。进一步,检测HCC中survivin的表达并采用反义寡核苷酸封闭治疗。最后,观测sTRAIL和IL-12联合抗癌效果。结果 肝癌组织DR表达量显著强于正常肝组织DR表达量。60例肝癌组织中54例不表达诱捕受体DcRl,25例不表达DcR2,而20例正常肝组织均表达DcR。两种．HCC细胞株中DcR1表达缺失。经sTRAIL(100ng/ml)处理24h,HCC细胞凋亡发生率约10％,而Jurkat细胞凋亡率达70％以上。体外pIRES-EGFP-sTRAIL转染对肝癌细胞杀伤作用不敏感。体内直接瘤体注射pIRES-EGFP-sTRAIL可对裸鼠肝癌无明显抑制作用。HCC高表达survivin,反义寡核苷酸封闭可部分逆转TRAIL耐药。IL-12使survivin表达明显下调,显著加强TRAIL对HCC细胞的杀伤作用。结论 HCC对TRAIL诱导的凋亡有耐药现象。survivin参与HCC对TRAIL的耐药机制,反义寡核苷酸封闭可部分逆转TRAIL耐药。IL-12可通过抑制siurvivin表达增强TRAIL对HCC杀癌作用。联合基因治疗(如TRAIL和IL-12基因)可能成为一种有前途HCC治疗方案。     

TRAIL的抗肝细胞癌作用研究

目的 探讨TRAIL对HCC的治疗作用。方法 用不同浓度TRAIL处理肝癌细胞株HepG2、SMMC7721，观察经药物处理前后肿瘤细胞的凋亡发生率。采用分子克隆技术构建了真核表达质粒pIRES-EGFP-TRAIL，转染肝癌细胞株HepG2、SMMC7721细胞，观察其疗效。体内实验建立裸鼠肝癌模型，观察TRAn。的抑癌作用。结果TRAR，(100ng／m1)处理24h，肝癌细胞凋亡发生率约10％，而Jurkat细胞凋亡率达70％以上，胆管癌细胞QBC939凋亡发生率约50％。真核表达质粒TRAIL体外转染肝癌细胞后对肝癌细胞的生长无显著性的抑制作用。体内直接瘤体注射pIRES-EGFP-TRAIL可有效的导入TRAIL基因并获得高表达，但对裸鼠肝癌无明显抑制作用。结论 肝细胞癌对TRAIL诱导的凋亡有耐药现象，提示HCC中存在抑制TRAIL诱导凋亡的因素，单一的TRAIL疗HCC疗效有限。     

移植物浸润T淋巴细胞肿瘤坏死因子相关凋亡诱导配体及受体DR4和DR5表达与大鼠小肠移植急性排斥反应的相关性

目的 探讨浸润T淋巴细胞七的DR4、DR5表达同小肠移植急性排斥反应的关系.方法 将2种近交系大鼠(SD、Wistar)54只按随机配对法分为A、B、C3组.A组大鼠为对照组(18只)行虚拟手术;B组(18只)大鼠行同系小肠移植;C组(18只)大鼠行不同品系小肠移植.各组大鼠于术后5 d取移植肠样本分别做HE染色和免疫荧光双标记染色.采用免疫荧光染色、激光共聚焦技术测定各组标本浸润T淋巴细胞肿瘤坏死因相关凋亡诱导配体及DR4、DR5的表达情况.结果 A组大鼠小肠黏膜正常,B组大鼠小肠表现为免疫耐受,C组大鼠表现为急性排斥反应.C组大鼠高T淋巴细胞表达肿瘤坏死因子相关凋亡诱导配体与A、B组大鼠比较差异有统计学意义(P < 0.01);A、B组大鼠浸润T淋巴细胞DR4、DR5均呈高表达,C组大鼠呈低表达,C组大鼠与A、B组比较差异有统计学意义(P < 0.01);A、B组大鼠比较差异无统计学意义(P > 0.05).结论 急性排斥反应的发生可能与浸润T淋巴细胞DR的低表达有关.减少浸润淋巴细胞DR表达的下调,或者上调DR将有助于控制急性排斥反应,诱导免疫耐受.     

Effect of Smac on TRAIL-induced apoptosis of prostate cancer cell line PC-3 and the molecular mechanism

The effect of Smac gene on the TRAIL-induced apoptosis of the prostate cancer cell line PC-3 and the molecular mechanism were investigated. The Smac gene was transfected into PC-3 cells under the induction of liposome. The intrinsic Smac gene expression was detected by Western blotting. After treatment with TRAIL as an apoptosis inducer, in vitro cell growth activity was as-sayed by MTT colorimetry. The apoptosis rate of PC-3 cells was determined by annexin Ⅴ-FITC and propidium iodide staining flow cytometry. The expression of cellular XIAP and caspase-3 genes was examined by Western blotting. Smac-transfected cells (PC-3/Smac group) had significantly in-creased Smac protein level as compared with PC-3 controls (P<0.01). After induction with 100-200 ng/mL TRAIL for 12-36 h, cellular proliferation rate in PC-3/Smac group was significantly lower than in PC-3 controls (P<0.05). After induction with 100 ng/mL TRAIL for 24 h, the apoptosis rate in PC-3/Smac group was significantly enhanced as compared with that of PC-3 controls (P<0.05). Ac-cordingly, the XIAP expression level was down-regulated significantly (P<0.05) and caspase-3 sub-unit P20 was up-regulated significantly (P<0.05). It is suggested that the over-expression of cellular Smac can inhibit inhibitor of apoptosis proteins (IAPs), enhance caspases activity and the apoptosis rate of PC-3 cells induced by TRAIL, which may provide a useful experimental basis for prostate cancer therapy.