Immunohistochemical analysis of Smac/DIABLO expression in human carcinomas and sarcomas

Second mitochondria-derived activator of caspases (Smac/DIABLO) is released from mitochondria into the cytosol during apoptosis, promoting caspase activation by neutralizing the inhibition of inhibitor of apoptosis proteins (IAPs) on caspases. Alteration of apoptosis is essential for cancer development, and cancer cell death by radiation and chemotherapy is largely dependent upon apoptosis. In this study, archival tissues of 100 carcinomas and 50 sarcomas from various origins were analyzed by immunohistochemistry for the expression of Smac/DIABLO. Smac/DIABLO immunoreactivity was seen in 62 of 100 (62%) carcinomas, including 42 of 60 stomach carcinomas, 7 of 10 colorectal carcinomas, 4 of 10 lung carcinomas, 7 of 10 ovarian carcinomas, and 2 of 10 prostate carcinomas. Smac/DIABLO is expressed in 11 of 50 (22%) sarcomas, including 2 of 8 malignant schwannomas, 5 of 11 rhabdomyosarcomas, 2 of 7 malignant fibrous histiocytomas, 1 of 6 leiomyosarcomas, 0 of 8 angiosarcomas, 0 of 8 liposarcomas, and 1 of 2 Ewing's sarcomas. These data demonstrated that Smac/DIABLO expression levels vary depending on the individual cancer types. Furthermore, the present study showed that many human cancers do not express Smac/DIABLO, and suggest that lack of Smac/DIABLO expression in the cancer cells may inhibit apoptosis, thereby promoting their survival.     

艾灸血浆对离体人胃黏膜上皮细胞损伤的保护作用及其线粒体细胞凋亡通路机制

目的:探讨艾灸血浆对胃黏膜细胞凋亡的影响,揭示艾灸对胃黏膜细胞的保护作用及其信号转导机制。方法:24名健康人随机等分为艾灸穴位组和艾灸非穴位组,分别艾灸中脘、关元和足三里穴及非穴位对照点各10 d。将人体胃黏膜上皮(GES-1)细胞分为空白组、模型组、艾灸穴位血浆组、艾灸非穴位血浆组,采用含8%乙醇的培养液造成GES-1细胞损伤模型,分别加以预先提取的灸前人体血浆、艾灸穴位和非穴位血浆。流式细胞技术检测细胞凋亡率;Western-blot法检测细胞内热休克蛋白70(HSP70)、第二个线粒体来源的胱氨酸酶激活物(Smac)、凋亡诱导因子(AIF)的表达;细胞免疫化学法检测半胱氨酸天冬酸蛋白酶-3、9(Caspase-3、9)的表达。结果:模型组与空白组比较,细胞凋亡率明显增加,HSP70、Smac、AIF、Caspase-3、Caspase-9表达均上调(均P<0.01);艾灸穴位血浆组与模型组比较,凋亡率明显下降(P<0.01),HSP70表达进一步提高(P<0.01),Smac、AIF、Caspase-3、Caspase-9表达下调(均P<0.01);艾灸非穴位血浆组与模型组比较,凋亡率、Smac表达下降,Caspase-3、Caspase-9表达也下调(均P<0.01),但高于艾灸穴位血浆组(P<0.05,P<0.01)。结论:艾灸中脘、关元和足三里穴位后提取的人体血浆能抑制GES-1细胞凋亡,其信号转导通路可能是:促进细胞内HSP70合成,通过线粒体凋亡通路,抑制Smac、AIF表达,同时阻断其与Caspase-9的结合,减少Caspase-3含量,抑制细胞凋亡。     

第二线粒体源性胱氨酸酶激活因子及其类似物与肿瘤的相关性研究进展

第二线粒体源性胱氨酸酶激活因子(Smac)是一种存在线粒体中并具有促凋亡作用的蛋白,Smac主要通过参与细胞凋亡的线粒体途径和死亡受体途径的下游反应,特异性地与凋亡抑制因子(IAPs)结合,解除IAPs对Caspase的抑制效应从而促进细胞凋亡。在肿瘤细胞中,Smac的过表达可以抑制或延缓肿瘤的发生发展过程,提高细胞浆Smac含量可增强细胞对放化疗的敏感性。人工合成的Smac类似物可通过级联放大效应提高肿瘤细胞对放化疗的敏感性,具有高效、低毒、高通透性等优点,为肿瘤的治疗提供了新的方法和思路,具有重要的临床意义。该研究就Smac、Smac类似物与肿瘤的相关性研究进展做一综述。     

全反式维甲酸对环孢素诱导的肾小球系膜细胞增殖与凋亡的影响及其机制

目的  探讨全反式维甲酸（ATRA）对环孢素（CsA）诱导的大鼠肾小球系膜细胞增殖及凋亡的影响及机制。方法  采用不同剂量ATRA作用于不同剂量CsA诱导下的肾小球系膜细胞。采用MTT比色法检测细胞增殖,Hoechst 33258荧光染色观察细胞凋亡形态,后用流式细胞仪检测细胞凋亡率,免疫荧光法检测线粒体促凋亡的Smac蛋白的表达。结果  与对照组比较,CsA剂量为0.5 μg/mL及以上可抑制细胞増殖,CsA剂量为1.0 μg/mL及以上可诱导细胞凋亡,且Smac蛋白的表达随CsA剂量的增加而增加,具有剂量和时间依赖的特征（均为P＜0.05）。而与CsA组比较,CsA+ATRA处理组对细胞增殖的抑制作用更为明显,而加入ATRA可呈剂量依赖性抑制CsA诱导的肾小球系膜细胞凋亡及Smac蛋白的表达（均为P＜0.05）。结论  CsA可抑制肾小球系膜细胞增殖,诱导其凋亡并刺激Smac蛋白的表达。ATRA可以抑制CsA诱导的肾小球系膜细胞凋亡,且可能是通过Smac信号通路介导的。     

Incretin mimetics as a novel therapeutic option for hepatic steatosis.

BACKGROUND: Fat accumulation in the liver or non-alcoholic fatty liver disease (NAFLD) is regarded as a key pathogenic factor and component of the metabolic syndrome. It was reported that administration of the incretin mimetic exenatide reversed hepatic steatosis in an obese mouse model. We had the opportunity to study the effect of additional exenatide administration on liver fat content in a patient with type 2 diabetes. CASE REPORT: A 59-year-old male with poorly controlled type 2 diabetes was treated with exenatide in addition to metformin monotherapy. Following 44 weeks of exenatide therapy, mean the liver fat measured by liver spectroscopy declined from 15.8% to 4.3%. This dramatic decrease in liver fat was accompanied by significant beneficial changes in several cardiovascular disease risk factors and improvement of all liver enzymes, in particular alanine aminotransferase, the most important marker of liver steatosis. CONCLUSION: This case report suggests that the incretin mimetic exenatide decreases hepatic fat accumulation and may play a role in the future treatment of NAFLD, and the associated insulin resistance and cardiovascular risk factors in an ever-growing high-risk population.     

Development of thrombopoietin receptor agonists for clinical use

Summary.  Thrombopoietin (TPO) is an essential hematopoietic cytokine for megakaryopoiesis. In 2002, we demonstrated that pegylated-recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) increased platelet counts in patients with chronic immune thrombocytopenic purpura (ITP) in a Phase I/II clinical trial. After the cessation of clinical trials of PEG-rHuMGDF because of severe thrombocytopenia or pancytopenia due to the development of the neutralizing antibody cross-reacting with endogenous TPO, second generation non-immunogenic TPO receptor agonists have been developed. A small molecule eltrombopag and Romiplostim were approved for clinical use by FDA in 2008 to treat patients with chronic ITP who are refractory to the prior therapy. Although the efficacy of both TPO receptor agonists is convincing for the refractory ITP, further investigation is necessary to assess the potential long-term side effects and clinical applications of these therapies for other thrombocytopenic conditions.     

蟾蜍灵诱导HL-60细胞凋亡过程中对Bcl-2、Survivin、Smac/DIABLO表达的影响

目的 研究蟾蜍灵在诱导HL-60细胞凋亡过程中，对线粒体凋亡途径相关基因Bcl-2、Bax、Survivin及Smac／DIABLO表达的影响。方法 采用锥虫蓝拒染法检测细胞存活情况，细胞形态学观察及流式细胞术检测细胞凋亡，Western blot分析Bcl-2、Bax、Smac／DIABLO、Survivin及caspase-3蛋白表达，RT-PCR检测SurvivinmRNA表达。结果 蟾蜍灵抑制HL-60细胞增殖，24，48及72h的，IC50值分别为25．8，8．0及2．1nmol/L。蟾蜍灵大于50．0nmol/L时可明显诱导HL-60细胞凋亡。50．0nmol／L蟾蜍灵作用6，12，24及48h，Bcl-2蛋白表达分别下调至作用前的88．6％，53．3％，19．2％及9．5％，而Bax蛋白表达无明显变化，Bcl-2／Bax比值由2．0分别降至1．7，1．1，0．4及0．2。Survivin蛋白表达分别下调至作用前的75．2％，54．8％，37．5％及20．3％；Survivin mRNA表达在作用6，12和24h后分别下调至作用前的85．7％，39．4％和12．5％，在作用48h后几乎检测不到。50．0nmol／L蟾蜍灵作用12，24及48h，线粒体部分的Smac／DIABLO蛋白表达分别下调至作用前的77．5％，21．2％及15．3％，而胞浆部分的Smac／DIABLO蛋白表达分别上调至作用前的1．4，2．0．及3．5倍。蟾蜍灵作用8～48h可检测到caspase-3的活化亚基。结论 蟾蜍灵诱导的HL-60细胞凋亡与Bcl-2及Survivin表达下调、线粒体释放Smac／DIABLO及caspase-3活化有关。     

Inhibitor of apoptosis proteins as targets for anticancer therapy

Cell death by apoptosis plays a critical role in regulating the subtle balance between cell death and proliferation to maintain tissue homeostasis. Accordingly, tipping the balance in either direction may cause human disease. Too little cell death may promote tumor formation and progression. In addition, killing of cancer cells by current therapies is largely due to induction of apoptosis in tumor cells. Since a hallmark of human cancers is their resistance to apoptosis, there is a demand to develop novel strategies that restore the apoptotic machinery in order to overcome cancer resistance. Inhibitor of apoptosis proteins (IAPs) block apoptosis at the core of the apoptotic machinery by inhibiting caspases. Elevated levels of IAPs are found in many human cancers and have been associated with poor prognosis. Recent insights into the role of IAPs have provided the basis for various exciting developments that aim to modulate the expression or function of IAPs in human cancers. Targeting IAPs (e.g., by antisense approaches or small-molecule inhibitors) presents a promising novel approach to either directly trigger apoptosis or to potentiate the efficacy of cytotoxic therapies in cancer cells. Thus, inhibition of IAPs such as X chromosome-linked IAP may prove to be a successful strategy to overcome apoptosis resistance of human cancers that deserves further exploitation.     

Calorie restriction and sirtuins revisited

Calorie or dietary restriction (CR) has attracted attention because it is the oldest and most robust way to extend rodent life span. The idea that the nutrient sensors, termed sirtuins, might mediate effects of CR was proposed 13 years ago and has been challenged in the intervening years. This review addresses these challenges and draws from a great body of new data in the sirtuin field that shows a systematic redirection of mammalian physiology in response to diet by sirtuins. The prospects for drugs that can deliver at least a subset of the benefits of CR seems very real.