The Protein Toxins Ricin and Shiga Toxin as Tools to Explore Cellular Mechanisms of Internalization and Intracellular Transport

Protein toxins secreted by bacteria and found in plants can be threats to human health. However, their extreme toxicity can also be exploited in different ways, e.g., to produce hybrid toxins directed against cancer cells and to study transport mechanisms in cells. Investigations during the last decades have shown how powerful these molecules are as tools in cell biological research. Here, we first present a partly historical overview, with emphasis on Shiga toxin and ricin, of how such toxins have been used to characterize processes and proteins of importance for their trafficking. In the second half of the article, we describe how one can now use toxins to investigate the role of lipid classes for intracellular transport. In recent years, it has become possible to quantify hundreds of lipid species using mass spectrometry analysis. Thus, it is also now possible to explore the importance of lipid species in intracellular transport. The detailed analyses of changes in lipids seen under conditions of inhibited toxin transport reveal previously unknown connections between syntheses of lipid classes and demonstrate the ability of cells to compensate under given conditions.     

心肌细胞中自噬平衡的研究进展

心肌细胞中自噬广泛发生,近年来大量实验和临床研究表明,在心肌细胞中不同情况下自噬起着不同的作用,例如在心肌细胞衰老及缺血早期,自噬起着保护作用;而在再灌注期起着损伤作用。据研究,中药对自噬平衡起着重要的调节作用,本文对心肌细胞中自噬平衡机制以及中药对自噬平衡的调节进行综述。     

儿童血清维生素D水平、自噬、免疫调节及机体各系统疾病的相关性综述

维生素D对人体作用广泛且复杂,是一种与特异性受体相结合而发挥作用的一类脂溶性类固醇激素,其受体在多种组织细胞中都有分布,含量最多的器官为小肠、肾脏、甲状旁腺及骨骼,此外,心血管、胃肠道、中枢神经系统等其他脏器也有维生素D受体的表达。血清维生素D水平异常时,机体会出现相应的病理改变,如:呼吸道疾病、消化道疾病、泌尿系统疾病、风湿免疫疾病、自身免疫性疾病、肥胖等疾病,本文就维生素D水平、自噬、免疫调节及各系统疾病的相关性进行综述。     

脓毒血症患者血浆皮质醇、乳酸、中性粒细胞捕获网表达水平与患者临床预后

目的探讨脓毒血症患者血浆皮质醇、乳酸、中性粒细胞捕获网表达水平与患者临床预后的关系。方法选取90例2017年11日-2018年11月间本院就诊的脓毒血症患者患者作为研究对象,根据APACHE-II评分分为危重组25例和非危重组65例,并选取30例健康体检者作为对照组,所有患者均检测血清中血浆皮质醇、乳酸、中性粒细胞捕获网,采用相关性分析探讨F、Lac、Cf-DNA/NETs与患者临床特点关系,采用Logistic回归分析探讨患者血清中脓毒血症患者预后不良的危险因素。结果危重组患者F、Lac、Cf-DNA水平分别为(625.5±65.4)μg/L、(3.2±0.8)mol/L、(57.4±6.4)ng/ml明显高于非危重组和对照组患者,差异有统计学意义(P<0.05)。血清中F、Lac、Cf-DNA/NETs均与心率、APACHE II评分呈正相关(P<0.05),与平均动脉压、氧分压、中性静脉压呈负相关,F、Lac、Cf-DNA/NETs、APACHE II评分是患者脓毒血症死亡的独立危险因素(P<0.05)。结论血清中皮质醇、乳酸钠、中性粒细胞捕获网是患者预后不良的重要危险因素。     

Bcl-2和Beclin-1在肝癌组织中的表达及其相关性

目的:探讨Bcl-2和Beclin-1在肝癌(hepatocellular carcinoma,HCC)患者术后复发中的作用,并分析肝癌组织中Bcl-2和Beclin-1的蛋白表达是否具有相关性。方法:收集肝癌组织114例,采用免疫组织化学法检测各组中 Bcl-2蛋白和Beclin-1蛋白的表达情况。与患者临床资料进行统计学分析。结果:利用χ2检验发现Bcl-2在HCC中的表达仅与患者的肿瘤个数程度相关,Beclin-1在HCC中的表达仅与患者的肿瘤分化程度相关,差异具有统计学意义。HCC中Bcl-2和Beclin-1蛋白的表达呈负相关（r =-0.61,P＜0.000 1）。Bcl-2表达阳性影响患者的预后(Log-rank=8.892,P=0.002 9),Beclin-1表达阴性影响患者的预后(Log-rank=5.350,P=0.020 7)。多因素分析显示肿瘤的肝内复发与肝内肿瘤个数、Bcl-2表达有关。结论:Bcl-2和Beclin-1在肝癌中具有相关性,共同影响患者的预后。     

Prucalopride通过促进自噬抑制胶质瘤细胞U251增殖

目的:研究Prucalopride对胶质瘤U251细胞增殖、自噬、凋亡的影响,并探讨其相关信号通路。方法:通过CCK8检测细胞增殖的变化;Transwell检测迁移和侵袭的变化;细胞流式实验、Western blot检测细胞凋亡的变化;Western blot检测自噬相关蛋白LC3、Beclin1、p62的表达;AKT/mTOR通路相关蛋白的变化。结果:CCK8显示Prucalopride显著抑制U251细胞的增殖（P＜0.05）;Transwell侵袭实验显示Prucalopride可以抑制脑胶质瘤细胞的迁移和侵袭（P＜0.05）;细胞流式实验显示Prucalopride促进U251细胞的凋亡（P＜0.05）,Prucalopride处理后细胞凋亡相关蛋白Bax、Active Caspase3水平升高,Bcl-2表达降低;自噬相关蛋LC3、Beclin1表达上调,p62表达下调;p-AKT蛋白和p-mTOR蛋白水平显著降低。结论:Prucalopride通过抑制AKT/mTOR信号通路激活自噬抑制U251细胞增殖和迁移,促进其凋亡。     

Adenosine 5'‐monophosphate‐activated protein kinase‐dependent mTOR pathway is involved in flavokawain B‐induced autophagy in thyroid cancer cells

Flavokawain B (FKB), a natural kava chalcone, shows potent antitumor activity in various types of cancer, although the mechanism of action remains unclear. In this study, we report that FKB has profound effects on the metabolic state of human thyroid cancer (TCa) cells, leading to high autophagy flux through upregulation of AMP‐activated protein kinase, which in turn inhibits mTOR and activates Beclin‐1 in TCa cells. We further report that the autophagy induced by FKB plays a prosurvival role in TCa cells both in vitro and in vivo. In conclusion, our findings provide evidence that combination treatment with FKB and pharmacological autophagy inhibitors will be a potential therapeutic strategy for the treatment of TCa.     

Demethylzeylasteral (ZST93) inhibits cell growth and enhances cell chemosensitivity to gemcitabine in human pancreatic cancer cells via apoptotic and autophagic pathways

The overall 5‐year survival rate of patients with human pancreatic cancer remains less than 8% because of its aggressive growth, early metastasis and resistance to conventional chemoradiotherapy. It is essential to develop innovative and effective therapeutic agents to improve its prognosis. Demethylzeylasteral (ZST93) is a novel triterpenoid monomer extracted from the xylem of Tripterygium roots. Our study aimed to assess the effects of ZST93 on cell proliferation and its role in the chemosensitivity to gemcitabine in human pancreatic cancer cells. The effects of ZST93 on cancer cell proliferation, cell cycle distribution, apoptosis and autophagy were evaluated in various human pancreatic cancer cell lines, and the antitumor effects of ZST93 alone and in combination with gemcitabine were identified in a xenograft mouse model. The results showed that ZST93 could inhibit the proliferation of pancreatic cancer cells and arrest cell cycle at G0/G1 phase by regulating the expression of Cyclin D1 and Cyclin A2. Moreover, ZST93 killed pancreatic cancer cells through two different mechanisms: inducing autophagic cell death at low concentrations and apoptotic cell death at high concentrations. Furthermore, ZST93 could enhance the chemosensitivity of pancreatic cancer cells to gemcitabine both in vitro and in vivo through modulation of the cross talk between autophagy and apoptosis. ZST93 is a potential therapeutic agent for developing novel therapeutic strategies in human pancreatic cancer.