ATM基因区的常见变异与2型糖尿病患者对二甲双胍的降糖反应相关

在2型糖尿病的治疗中,大多数国家和国际指南推荐二甲双胍为一线药物.尽管二甲双胍的临床应用已有50多年,但它的作用机制尚没有完全阐明.已经明确二甲双胍是通过抑制线粒体呼吸链.导致细胞AMP增加,从而激活AMP-激活的蛋白激酶(AMPK)来发挥作用,但仍然不清楚是否AMPK是其唯一的作用靶点.     

二甲双胍抗肿瘤机制研究新进展

二甲双胍是治疗糖尿病的一线药物,除具有降糖作用外,还有抗肿瘤的作用.但是否可以降低2型糖尿病患者恶性肿瘤的发病率和病死率尚存在争议.二甲双胍抗肿瘤作用的机制目前发现可能包括激活腺苷酸活化蛋白激酶(AMPK)途径、诱导细胞周期停滞、促进细胞凋亡、抑制肿瘤细胞侵袭转移、抑制炎症反应及杀灭肿瘤干细胞等.该文就二甲双胍抗肿瘤作用的相关机制和临床研究予以综述.     

预防性给予二甲双胍减轻小鼠尼古丁戒断引起的焦虑

目的:研究二甲双胍对雌性小鼠尼古丁戒断后焦虑样行为的改善作用及可能的机制。方法:将C57BL/6J雌鼠分为两组,分别为尼古丁戒断组(N组,即戒断前只注射了尼古丁),和二甲双胍预处理组(NM组,在尼古丁戒断前给予二甲双胍)。采用美加明诱导尼古丁戒断相关行为。利用埋珠实验、高架十字迷宫实验及旷场实验评估尼古丁戒断引起的焦虑样行为。通过实时荧光定量PCR检测小鼠海马中Prkaa1,Prkaa2,Prkag1的表达。结果:与没有二甲双胍预处理的小鼠相比,用二甲双胍预处理的小鼠显著减少了埋珠的数量(P<0.01):同时,进入开放臂中的次数显著增加(P<0.001);旷场实验结果无显著差异。Prkaa1基因在海马中的表达水平增加(P<0.05),Prkag1和Nrg3基因的表达水平显著下降(P<0.001)。结论:预防性给予二甲双胍可减轻雌性小鼠尼古丁戒断后的焦虑症状,其作用机制可能是通过AMPK的α1亚基激活AMPK通路。     

二甲双胍抗膀胱癌药理机制的研究进展

二甲双胍已成为临床治疗2型糖尿病的一线口服降糖药,最新研究表明二甲双胍除了能通过改善胰岛素抵抗、抑制肝脏糖异生等参与调节血糖水平外,还能明显降低糖尿病患者中卵巢癌、肝癌、肺癌等多种癌症的发生率、复发率和死亡率。综述了二甲双胍能通过激活AMPK信号通路、诱导细胞周期停滞及细胞凋亡、抑制血管生成、抑制膀胱癌干细胞增殖、增强化疗药物等对膀胱癌细胞的疗效等多种分子机制产生抗膀胱癌的作用,展望了其成为新一代治疗膀胱癌药物的可能。     

二甲双胍不依赖腺苷酸活化蛋白激酶途径的抗肿瘤机制研究进展

二甲双胍是临床上广泛用来治疗2型糖尿病的口服降糖药。流行病学研究发现,二甲双胍与癌症的预防和治疗有着密切的关系。二甲双胍的抗肿瘤分子机制已成为研究热点。大部分研究认为,该药理作用依赖腺苷酸活化蛋白激酶(AMPK)的激活。近几年,部分学者提出二甲双胍通过非AMPK依赖途径抗肿瘤的机制,可改善胰岛素敏感性,下调Ras相关GTP结合蛋白Rag活性和DNA损伤反应调节基因1的表达,抑制哺乳动物雷帕霉素靶蛋白(mTOR)信号通路,抑制Ras相关C3肉毒杆菌毒素底物活性、细胞分裂周期蛋白42和基质金属蛋白酶的表达等多种途径抑制肿瘤细胞的生长、侵袭和迁移。本综述以此为切入点,综述二甲双胍不依赖AMPK途径的抗肿瘤机制研究进展,为其抗肿瘤作用机制的探讨展示新视角。     

二甲双胍抗头颈部肿瘤的研究进展

二甲双胍是治疗2型糖尿病的首选药物,近年来研究发现二甲双胍除了降糖作用外,还可以抗炎、抗衰老、抗肿瘤等作用。通过查阅大量文献就二甲双胍抗头颈部肿瘤的研究进展进行综述,并介绍了二甲双胍通过激活腺苷酸活化蛋白激酶（AMPK）信号通路、上调相关微小RNA（miRNAs）、抑制信号转导与转录激活因子3（STAT3）信号通路等作用机制抗头颈部肿瘤。     

二甲双胍对葡萄糖-6-磷酸酶基因表达的抑制作用及其机制

目的探讨二甲双胍对葡萄糖-6-磷酸酶(G6Pase)基因表达作用及其分子机制。方法应用稳定表达G6Pase的鼠肝细胞瘤H4ⅡE M1.3细胞,一组细胞分别给予二甲双胍0.1～5.0mmol·L-1孵育16h;另一组细胞先加入化合物C 20μmol·L-1,Bay11-7085 5μmol·L-1或雷帕霉素25nmol·L-1作用30min后,再加入二甲双胍2mmol·L-1共育16h,采用荧光素酶报告基因检测方法测定G6Pase基因表达水平;细胞加入化合物C 20μmol·L-1作用30min后,再分别加入二甲双胍2mmol·L-1、5-氨基-4-甲酰胺咪唑核糖核苷酸(AICAR)1mmol·L-1孵育15min,Western印迹法检测腺苷酸活化蛋白激酶(AMPK)蛋白表达及其磷酸化水平;细胞加入二甲双胍2mmol·L-1和胰岛素1μmol·L-1作用15min,Western印迹法检测蛋白激酶B(Akt)蛋白表达及其磷酸化水平。结果二甲双胍0.5,1,2和5 mmol·L-1作用16h可以显著抑制G6Pase基因表达(P<0.05,P<0.01),二甲双胍0.5和5mmol·L-1时,分别抑制G6Pase基因表达26%(P<0.05)和85%(P<0.01)。AMPK抑制剂化合物C可部分逆转二甲双胍的抑制作用(P<0.05);二甲双胍可诱导AMPK磷酸化,与AICAR作用相似,但这一作用可被化合物C抑制。结论二甲双胍抑制G6Pase基因表达,其作用机制可能与激活AMPK有关,而可能与Akt,雷帕霉素靶蛋白(mTOR)及核因子-κB(NF-κB)介导的通路无关。     

二甲双胍对骨肉瘤MG-63细胞形态、凋亡和终末分化的影响分析

目的:研究二甲双胍对骨肉瘤MG-63细胞的形态、凋亡和终末分化的影响,分析其与磷酸腺苷激活的蛋白激酶活性及胚胎干细胞标志物Nanog、Oct4表达情况的相关性.方法:选取人骨肉瘤MG63细胞作为研究对象,利用悬浮球生长实验将其诱导为骨肉瘤干细胞,随机将培养的细胞分为实验组和对照组,实验组培养细胞给予二甲双胍处理,观察处理前后骨肉瘤干细胞的形态及分化能力,分析二甲双胍对骨肉瘤干细胞凋亡的影响,并比较干细胞标志物Nanog及Oct4的阳性率,检测二甲双胍作用前后骨肉瘤干细胞中磷酸腺苷激活的蛋白激酶AMPK、雷帕霉素靶蛋白mTOR以及核糖体蛋白S6激酶p70S6K信号通路的表达情况.结果:实验组培养细胞的Nanog阳性率为45.2%,Oct4阳性率为74.7%;对照组培养细胞的Nanog阳性率为73.5%,Oct4阳性率为95.3%;两组培养细胞的Nanog及Oct4的阳性率比较差异均具有统计学意义(P<0.05).实验组培养细胞的磷酸腺苷激活的蛋白激酶AMPK相对表达量明显高于对照组,雷帕霉素靶蛋白mTOR以及核糖体蛋白S6激酶p70S6K的相对表达量明显低于对照组,差异均具有统计学意义(P<0.05).结论:二甲双胍可破坏骨肉瘤细胞的形态,抑制其分化,作用机制可能与Nanog及Oct4表达的下调、AMPK的激活有关.     

二甲双胍抑制SREBP-1c改善高脂诱导的骨骼肌胰岛素抵抗

目的二甲双胍已成为治疗2型糖尿病的一线药物,前期研究结果提示固醇调节元件结合蛋白-1c(sterol regulatory element binding protein-1c,SREBP-1c)抑制胰岛素受体底物-1(insulin receptor substrate-1,IRS-1)基因转录表达,在高脂诱导骨骼肌胰岛素抵抗中起关键作用。该研究探讨SREBP-1c在二甲双胍改善高脂诱导骨骼肌胰岛素抵抗中的作用及机制。方法经500μmol·L-1PA处理的L6细胞被二甲双胍(1、10 mmol·L-1)干预24 h后,采用2-NBDG方法检测其葡萄糖摄取水平,Western blot检测SREBP-1c、FAS、p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)、AKT的蛋白表达。双荧光素酶报告基因实验检测二甲双胍对SREBP-1c和IRS-1基因转录的调控。CHIP定量分析二甲双胍处理后SREPB-1c蛋白与IRS-1启动子区域的相互作用。结果 L6肌管细胞经PA处理后,糖摄取下降,SREBP-1c及其下游分子FAS表达升高,胰岛素信号通路相关分子p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)/AKT表达下降;不同浓度二甲双胍干预后,L6肌管细胞糖摄取呈剂量依赖性增加,SREBP-1c、FAS表达下降,而p-IRS-1(Tyr608/612)、IRS-1、p-AKT(Ser473)/AKT表达升高。双荧光素酶报告基因实验结果显示二甲双胍抑制SREBP-1c启动子活性,增加IRS-1启动子活性。CHIP结果显示二甲双胍使SREBP-1c蛋白结合到IRS-1启动子区域的量下降约30%。结论二甲双胍通过抑制SREBP-1c改善高脂诱导的骨骼肌胰岛素抵抗。     

二甲双胍延长寿命的作用及其作用机制

通过药理学方法来降低有机体的衰老率从而延长寿命已成为目前的研究热点之一。二甲双胍是一种用于治疗2型糖尿病的常用双胍类药物,研究显示二甲双胍可以延缓衰老并延长寿命,它可以通过激活腺苷酸活化蛋白激酶（AMPK）、抑制哺乳动物雷帕霉素靶蛋白（mTOR）及其下游相关分子发挥其抗衰老作用。本文对二甲双胍延长线虫、转基因小鼠和大鼠的寿命及其作用机制进行综述。     

Dibenzoylmethane Protects Against CCl4-Induced Acute Liver Injury by Activating Nrf2 via JNK,AMPK, and Calcium Signaling

Oxidative stress is an important pathogenic factor in various hepatic diseases. Nuclear factor-erythroid 2-related factor-2 (Nrf2), which coordinates the expression of an array of antioxidant and detoxifying genes, has been proposed as a potential target for prevention and treatment of liver disease. Dibenzoylmethane (DBM) is a minor ingredient in licorice that activates Nrf2 and prevents various cancers and oxidative damage. In the present study, the mechanisms by which DBM activates Nrf2 signaling were delineated, and its protective effect against carbon tetrachloride (CCl₄)-induced liver injury was examined. DBM potently induced the expression of HO-1 in cells and in the livers of mice, but this induction was diminished in Nrf2-deficient mice and cells. Overexpression of Nrf2 enhanced DBM-induced HO-1 expression, while overexpression of a dominant-negative fragment of Nrf2 inhibited this induction. DBM treatment resulted in dissociation from Keap1 and nuclear translocation of Nrf2. Moreover, DBM activated Akt/protein kinase B, mitogen-activated protein kinases, and AMP-activated protein kinase and increased intracellular calcium levels. Inhibition of JNK, AMPK, or intracellular calcium signaling significantly suppressed the induction of HO-1 expression by DBM. Finally, DBM treatment significantly inhibited CCl₄-induced acute liver injury in wild-type but not in Nrf2-deficient mice. Taken together, our results revealed the mechanisms by which DBM activates Nrf2 and induces HO-1 expression, and provide molecular basis for the design and development of DBM and its derivatives for prevention or treatment of liver diseases by targeting Nrf2.     

Compound C stimulates heme oxygenase-1 gene expression via the Nrf2-ARE pathway to preserve human endothelial cell survival

We recently identified adenosine monophosphate-activated protein kinase (AMPK) as a novel inducer of heme oxygenase-1 (HO-1) and surprisingly found that compound C (6-[4-(2-piperidin-1-yl-ethoxy)-phenyl]-3-pyridin-4-yl-pyrazolo[1,5-a] pyrimidine), a cell-permeable inhibitor of AMPK, could also elevate HO-1 suggesting other AMPK-independent actions for this agent. In this study, we investigated the biochemical mechanism by which compound C stimulates HO-1 expression in human endothelial cells (ECs) and determined the biological significance of the induction of HO-1 by compound C in these cells. Compound C stimulated a concentration- and time-dependent increase in HO-1 expression and an increase in HO-1 promoter activity that was abrogated by mutating the antioxidant responsive elements (AREs) in the HO-1 promoter or by overexpressing a dominant negative mutant of NF-E2-related factor 2 (Nrf2). Compound C also stimulated Nrf2 expression this was associated with an increase in the production of reactive oxygen species and with a decline in intracellular glutathione levels. Interestingly, the glutathione donor N-acetyl-l-cysteine or the NADPH oxidase inhibitor apocynin blocked the induction of HO-1 by compound C. Finally, compound C stimulated EC death and this was potentiated by silencing HO-1 expression and reversed by the administration of CO, biliverdin, or bilirubin. In conclusion, this study demonstrates that compound C stimulates HO-1 gene expression in human vascular endothelium via the activation of the Nrf2/ARE signaling pathway to counteract compound C-mediated cell death. The ability of compound C to induce HO-1 expression may contribute to the pleiotropic actions of this agent and suggest caution when using compound C to probe for AMPK functions.     

Thymoquinone induces heme oxygenase-1 expression in HaCaT cells via Nrf2/ARE activation: Akt and AMPKα as upstream targets

Thymoquinone (TQ), an active constituent of Nigella sativa, possesses anti-inflammatory and anticancer properties. Multiple lines of evidence suggest that the induction of heme oxygenase-1 (HO-1) suppresses inflammation and carcinogenesis. In the present study, we examined the effect of TQ on HO-1 expression in human keratinocytes (HaCaT) and elucidated its underlying molecular mechanisms. TQ induced the expression of HO-1 in HaCaT cells in a concentration- and time-dependent manner. Treatment with TQ increased the localization of nuclear factor (NF)-erythroid2-(E2)-related factor-2 (Nrf2) in the nucleus and elevated the antioxidant response element (ARE)-reporter gene activity. Knockdown of Nrf2 abrogated TQ-induced HO-1 expression and the ARE luciferase activity. TQ induced the phosphorylation of extracellular signal-regulated kinase (ERK), Akt and cyclic AMP-activated protein kinase-α (AMPKα). Pharmacological inhibition of Akt or AMPKα, but not that of ERK, abrogated TQ-induced nuclear localization of Nrf2, the ARE-luciferase activity and the expression of HO-1. TQ also generated reactive oxygen species (ROS) and pretreatment with N-acetyl cysteine (NAC) abrogated TQ-induced ROS accumulation, Akt and AMPKα activation, Nrf2 nuclear localization, the ARE-luciferase activity, and HO-1 expression in HaCaT cells. Taken together, TQ induces HO-1 expression in HaCaT cells by activating Nrf2 through ROS-mediated phosphorylation of Akt and AMPKα.     

Novel chalcone derivatives as potent Nrf2 activators in mice and human lung epithelial cells

Nrf2-mediated activation of antioxidant response element is a central part of molecular mechanisms governing the protective function of phase II detoxification and antioxidant enzymes against carcinogenesis, oxidative stress, and inflammation. Nrf2 is sequestered in the cytoplasm by its repressor, Keap1. We have designed and synthesized novel chalcone derivatives as Nrf2 activators. The potency of these compounds was measured by the expression of Nrf2 dependent antioxidant genes GCLM, NQO1, and HO1 in human lung epithelial cells, while the cytotoxicity was analyzed using MTT assay. In vivo potency of identified lead compounds to activate Nrf2 was evaluated using a mouse model. Our studies showed 2-trifluoromethyl-2'-methoxychalone (2b) to be a potent activator of Nrf2, both in vitro and in mice. Additional experiments showed that the activation of Nrf2 by this compound is independent of reactive oxygen species or redox changes. We have discussed a quantitative structure-activity relationship and proposed a possible mechanism of Nrf2 activation.