PERK信号通路介导结肠癌细胞对5-氟尿嘧啶耐药机制的研究

目的:观察PERK蛋白对结肠癌细胞药物敏感性的影响，并进一步探讨其相关作用机制。方法:结肠癌细胞系HCT116分为三组:空白对照（Control）组、下调PERK表达（si-PERK）组、阴性对照（si-NC）组；采用免疫荧光及RT-PCR验证转染效率；利用CCK-8实验检测下调PERK表达后结肠癌细胞对化疗药物5-FU的敏感性变化；Annexin V-FITC凋亡实验检测下调PERK表达对结肠癌细胞凋亡的影响；利用RT-PCR及Western Blot实验检测PERK信号通路中关键分子eIF2α、ATF4、CHOP、XIAP的mRNA及蛋白表达变化。结果:RT-PCR实验表明:与正常对照组相比，si-PERK 组mRNA的表达显著下降（P＜0.05）,免疫荧光提示转染效率达80%以上；CCK-8实验发现与si-NC组相比，5-FU对 si-PERK组细胞的半数抑制浓度（IC50）明显降低（P＜0.01）；Annexin V-FITC凋亡实验发现与si-NC组相比，si-PERK组细胞的凋亡发生率显著升高（P＜0.05）；RT-PCR及Western Blot实验发现与si-NC组相比，si-PERK组细胞中PERK信号通路下游关键分子eIF2α、ATF4、CHOP的mRNA及蛋白表达均明显降低（P＜0.05）。结论:在结肠癌细胞中，抑制PERK表达后，其可能通过下调eIF2α、ATF4、CHOP的表达促进细胞发生凋亡，从而促进细胞对化疗药物5-FU的敏感性。     

XIAP与肿瘤化疗耐药关系的研究进展

细胞凋亡程度的降低是肿瘤发生的主要机理，造成肿瘤对化疗药物耐药的主要原因是化疗药物介导的细胞凋亡指数的下降。凋亡抑制蛋白在抑制细胞凋亡中起非常重要的作用,XIAP是IAP家族中抑制细胞凋亡的最主要成员。本文总结了近年来对XIAP抗凋亡机制的研究及其在肿瘤化疗耐药方面的作用。     

凋亡抑制蛋白XIAP与肿瘤多药耐药

XIAP(X-linked inhibitor of apoptosis protein)是凋亡抑制蛋白(inhibitors of apoptosis protein,IAP)家族中最有效的内源性凋亡抑制因子,可以通过直接抑制caspases或者参与信号转导途径抑制细胞凋亡。研究发现,XIAP与肿瘤多药耐药有密切关系,并且有可能成为逆转肿瘤多药耐药提高化疗效果的治疗新靶点。     

凋亡抑制蛋白XIAP和促凋亡因子Smac在胰腺癌化疗抵抗中的作用

目的探讨x-相关凋亡抑制蛋白（XIAP）和促凋亡因子Smac在胰腺癌细胞化疗抵抗中的作用，以及转染胞浆表达型Smac基因靶向下凋XIAP对化疗药物诱导的胰腺癌细胞凋亡的影响。方法应用流式细胞术检测顺铂、5-FU介导的Panc-1、BXPC-3的凋亡率及胞浆染色分析细胞XIAP表达变化，Western blot分析XIAP、Smac、Caspase-3表达水平；构建pEGFP-NI／Smac真核表达载体并转染胰腺癌Panc-1细胞，流式细胞术检测转染Smac基因前后Panc-1细胞的凋亡敏感性。结果与BXPC-3细胞相比，Panc-1对顺铂或5-FU介导的凋亡具有较强抵抗性，Western blot分析显示Panc-1细胞高表达XIAP，在化疗药物作用下化疗敏感细胞BXPC-3胞浆内XIAP水平下降明显多于Panc-1细胞，而且凋亡的BXPC-3细胞释放入胞浆内的成熟Smac蛋白水平明显高于Panc-1细胞。转染胞浆表达型Smac基因至化疗抵抗Panc-1细胞，可明显下调其XIAP表达水平，促进效应Caspase-3分子活化，显著提高顺铂、5-FU诱导的细胞凋亡率。结论胰腺癌细胞XIAP的表达水平下调与其化疗敏感性有关，XIAP是克服化疗抵抗的重要靶分子，而上调Smac活性蛋白的胞浆表达作为一种有效调节信号，通过拮抗XIAP的凋亡抑制作用协同化疗药物促进胰腺癌细胞凋亡。     

Xaf1与TNFα协同诱导细胞凋亡机制的初步探索

 [目的]利用Xaf1诱导细胞株,检测Xaf1与一些细胞凋亡激动剂协同诱导肿瘤细胞凋亡的能力,初步探索Xaf1诱导凋亡的机制.[方法]Xaf1与细胞凋亡激动剂协同诱导的细胞凋亡由流式细胞检测DNA含量来表示,免疫荧光显微镜检测法与细胞核浆分离法检测Xaf1诱导细胞中Xaf1与XIAP的亚细胞分布,免疫沉淀法检测Xaf1与XIAP的关联性.[结果]流式细胞术DNA含量检测发现Xaf1与TNFα显著协同诱导细胞凋亡,凋亡峰值为49%,而Xaf1与阿霉素无协同作用,凋亡峰值为27%,免疫荧光显微镜检测及细胞核浆分离法结果显示Xaf1位于细胞核内,而XIAP却位于细胞质.[结论]Xaf1与TNFα显著协同诱导细胞凋亡,其协同机制可能不是解除XIAP对胱冬肽酶活性的抑制.     

Anti-myeloma effect of homoharringtonine with concomitant targeting of the myeloma-promoting molecules, Mcl-1, XIAP, and β-catenin

Since a variety of cell intrinsic and extrinsic molecular abnormalities cooperatively promote tumor formation in multiple myeloma (MM), therapeutic approaches that concomitantly target more than one molecule are increasingly attractive. We herein demonstrate the anti-myeloma effect of a cephalotaxus alkaloid, homoharringtonine (HHT), an inhibitor of protein synthesis, through the induction of apoptosis. HHT significantly reduced Mcl-1, a crucial protein involved in myeloma cell survival, in all three myeloma cell lines examined, whereas certain BH3-only proteins, such as Bim, Bik, and Puma, remained unchanged following HHT treatment, and their expression levels depended on the cell type. HHT also reduced the levels of c-FLIP(L/S), activated caspase-8, and induced active truncated-Bid. Thus, HHT-induced apoptosis appears to be mediated via both intrinsic and extrinsic apoptosis pathways, and the resultant imbalance between BH3-only proteins and Mcl-1 may be pivotal for apoptosis by HHT. In addition, HHT treatment resulted in reduced levels of beta-catenin and XIAP proteins, which also contribute to disease progression and resistance to chemotherapy in MM. In combination, HHT enhanced the effects of melphalan, bortezomib, and ABT-737. These results suggest that HHT could constitute an attractive option for MM treatment though its ability to simultaneously target multiple tumor-promoting molecules.     

Thymoquinone (2-Isopropyl-5-methyl-1, 4-benzoquinone) as a chemopreventive/anticancer agent: Chemistry and biological effects

Cancer remains the topmost disorder of the mankind and number of cases is unceasingly growing at unprecedented rates. Although the synthetic anti-cancer compounds still hold the largest market in the modern treatment of cancer, natural agents have always been tried and tested for potential anti-cancer properties. Thymoquinone (TQ), a monoterpene and main ingredient in the essential oil of Nigella sativa L. has got very eminent rankings in the traditional systems of medicine for its anti-cancer pharmacological properties. In this review we summarized the diverse aspects of TQ including its chemistry, biosynthesis, sources and pharmacological properties with a major concern being attributed to its anti-cancer efficacies. The role of TQ in different aspects involved in the pathogenesis of cancer like inflammation, angiogenesis, apoptosis, cell cycle regulation, proliferation, invasion and migration have been described. The mechanism of action of TQ in different cancer types has been briefly accounted. Other safety and toxicological aspects and some combination therapies involving TQ have also been touched. A detailed literature search was carried out using various online search engines like google scholar and pubmed regarding the available research and review accounts on thymoquinone upto may 2019. All the articles reporting significant addition to the activities of thymoquinone were selected. Additional information was acquired from ethno botanical literature focusing on thymoquinone. The compound has been the centre of attention for a long time period and researched regularly in quite considerable numbers for its various physicochemical, medicinal, biological and pharmacological perspectives. Thymoquinone is studied for various chemical and pharmacological activities and demonstrated promising anti-cancer potential. The reviewed reports confirmed the strong anti-cancer efficacy of thymoquinone. Further in-vitro and in-vivo research is strongly warranted regarding the complete exploration of thymoquinone in ethnopharmacological context.     

Hemophagocytic lymphohistiocytosis and primary immune deficiency disorders

Hemophagocytic lymphohistiocytosis (HLH) is characterized by uncontrolled immune activation and is traditionally associated with inherited gene defects or acquired causes. In addition to abnormalities in cytotoxic granules and lysosomes, various primary immune deficiency disorders (PID) have been identified among patients suffering from HLH. Our purpose was twofold: to better characterize and detail the association between PID and HLH.     

中耳胆脂瘤中XIAP与Caspase-3的相关性研究

目的研究凋亡抑制蛋白XIAP、Caspase-3在胆脂瘤中的表达及胆脂瘤中的凋亡情况,探讨三者之间的关系,揭示XIAP、Caspase-3、凋亡在胆脂瘤发生发展中的作用,深入认识胆脂瘤发病机制,并为胆脂瘤的临床治疗方法提供新的思路。方法①运用免疫组织化学两步法检测25例胆脂瘤标本及10例外耳道正常皮肤组织中XIAP及Caspase-3的表达。②采用末端转移酶介导的原位缺口末端标记染色(TUNEL)技术进行检测两者组织的凋亡状态。结果①与正常上皮比较,胆脂瘤上皮中的XIAP蛋白表达明显下调(Z=2.411,P<0.05)。②胆脂瘤上皮中,Caspase-3的表达及细胞凋亡状况显著高于正常上皮(Zc=-2.877,Zt=-2.712,P<0.01)。③在胆脂瘤上皮中,XIAP表达与Caspase-3及凋亡均呈负相关(P<0.01),Caspase-3与凋亡呈正相关(P<0.01)。结论XIAP、Caspase-3的表达可能在胆脂瘤的发生、发展过程中起重要作用,它们参与胆脂瘤上皮的凋亡调控过程,可能是胆脂瘤的发病机制中一个重要因素。