CO and bilirubin inhibit doxorubicin-induced cardiac cell death

The clinical utility of anthracycline anticancer agents, especially doxorubicin (DOX), is limited by progressive toxic cardiomyopathy linked to cardiomyocyte apoptosis. This study examined the protective effects of CO and bilirubin on DOX-induced cardiomyocyte toxicity. In vitro, DOX significantly decreased the viability of H9c2 cells and increased apoptotic features, such as changes in nuclear morphology and caspase protease activation. CO and bilirubin significantly inhibited DOX-induced cell death and caspase-3 activation, which may be explained by increased Bcl-2 expression and inhibition of Bax expression. CO and bilirubin up-regulated the heme oxygenase-1 (HO-1), which was required for the protective effect of CO, and a single bilirubin treatment increased DOX-induced apoptosis in H9c2 cells. The inhibition of HO-1 with ZnPP resulted in a striking increase in apoptosis in the CO, bilirubin, and DOX-treated cells. Furthermore, HO-1 overexpression increased resistance against DOX-induced cytotoxicity in H9c2 cells. In conclusion, CO and bilirubin can inhibit DOX-induced apoptosis in H9c2 cardiomyocytes. These findings imply that the therapeutic index of anthracycline cancer chemotherapeutics can be improved by protecting against cardiomyocyte death.     

MicroRNA-126-5p在阿霉素所致损伤心肌中的表达及作用

目的:探讨微小RNA-126-5p(microRNA-126-5p)在阿霉素诱导的小鼠损伤心肌中的表达及在心肌细胞损伤中的作用。方法:采用BALB/c小鼠腹腔注射阿霉素的方法制备小鼠急、慢性阿霉素心肌损伤模型,苏木精-伊红(HE)染色检测小鼠心肌形态学改变,乳酸脱氢酶(LDH)试剂盒测定小鼠血清中的LDH活性,应用PowerLab数据采集分析系统检测小鼠心肌损伤情况。采用real-time PCR法检测阿霉素刺激大鼠心肌细胞株H9c2后micro RNA-126-5p的表达情况;转染microRNA-126-5p模拟物或抑制物,检测microRNA-126-5p模拟物及抑制物对阿霉素刺激后H9c2细胞microRNA-12-5p表达水平、LDH释放及caspase-3活化情况的影响。结果:在小鼠急、慢性阿霉素心肌损伤模型中,HE染色发现小鼠心肌纤维排列紊乱,肌原纤维溶解,局部有炎症细胞浸润;血清LDH释放增多(P0.05);左心室等容舒张期压力下降最大速率(-dp/dtmax)及左心室等容收缩期压力上升最大速率(+dp/dtmax)下降;real-time PCR检测发现小鼠心肌中microRNA-126-5p的表达显著上调。阿霉素所致H9c2心肌细胞损伤中也伴有microRNA-126-5p表达明显上调;进一步采用micro RNA-126-5p模拟物与抑制物转染H9c2细胞,发现与单纯阿霉素处理组相比,microRNA-126-5p模拟物组LDH的释放增加,caspase-3活性升高,而microRNA-126-5p抑制物组结果则与之相反。结论:阿霉素可诱导小鼠心肌细胞microRNA-126-5p的表达明显升高,进而降低心肌细胞活性,促进心肌细胞凋亡,发挥促心肌损伤作用。     

硫化氢通过调控NF-κB通路抑制阿霉素引起的心肌细胞炎症与细胞毒性

 目的：探讨硫化氢（H2S）是否通过调控核因子κB(NF-κB)通路抑制阿霉素（DOX）引起的心肌细胞炎症反应与细胞毒性。方法：应用Western blotting法测定NF-κB p65表达;酶联免疫吸附试验（ELISA）测定白细胞介素（IL）-1β、IL-6及肿瘤坏死因子α(TNF-α)的分泌水平;细胞计数盒（CCK-8）检测细胞存活率,Hoechst 33258核染色法检测凋亡细胞的形态学及数量的变化。结果：应用5 μmol/L DOX处理H9c2心肌细胞明显上调磷酸化NF-κB p65（p-p65）表达水平,并引起炎症反应和细胞毒性,表现为IL-1β、IL-6、TNF-α的分泌水平升高、凋亡细胞数量增多及细胞存活率降低。400 μmol/L NaHS（H2S供体）预处理30 min能显著抑制DOX对心肌细胞p-p65表达的上调作用,并减轻DOX引起的炎症反应和细胞损伤,使IL-1β、IL-6、TNF-α的分泌水平下降、凋亡细胞数量降低及细胞存活率升高。与NaHS的作用相似,NF-κB抑制剂吡咯烷二硫代氨基甲酸盐（PDTC,100 μmol/L）预处理也能阻断DOX引起的心肌炎症反应和细胞毒性。IL-1受体拮抗剂（IL-1Ra, 20 μg/L）与DOX共处理能拮抗DOX对心肌细胞NF-κB p65的激活作用及细胞毒性作用。结论：在DOX引起的心肌细胞炎症中,NF-κB通路与IL-1β之间存在正的相互作用;H2S可通过抑制NF-κB通路保护心肌细胞对抗DOX引起的炎症反应与细胞毒性。     

Protective effect of guggulsterone against cardiomyocyte injury induced by doxorubicin in vitro

ABSTRACT: BACKGROUND: Doxorubicin (DOX) is an effective antineoplastic drug; however, clinical use of DOX is limited by its dose-dependent cardiotoxicity. It is well known that reactive oxygen species (ROS) play a vital role in the pathological process of DOX-induced cardiotoxicity. For this study, we evaluated the protective effects of guggulsterone (GS), a steroid obtained from myrrh, to determine its preliminary mechanisms in defending against DOX-induced cytotoxicity in H9C2 cells. METHODS: In this study, we used a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H- tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release measurements, and Hoechst 33258 staining to evaluate the protective effect of GS against DOX-induced cytotoxicity in H9C2 cells. In addition, we observed the immunofluorescence of intracellular ROS and measured lipid peroxidation, caspase-3 activity, and apoptosis-related proteins by using Western blotting. RESULTS: The MTT assay and LDH release showed that treatment using GS (1--30 muM) did not cause cytotoxicity. Furthermore, GS inhibited DOX (1 muM)-induced cytotoxicity in a concentration-dependent manner. Hoechst 33258 staining showed that GS significantly reduced DOX-induced apoptosis and cell death. Using GS at a dose of 10--30 muM significantly reduced intracellular ROS and the formation of MDA in the supernatant of DOX-treated H9C2 cells and suppressed caspase-3 activity to reference levels. In immunoblot analysis, pretreatment using GS significantly reversed DOX-induced decrease of PARP, caspase-3 and bcl-2, and increase of bax, cytochrome C release, cleaved-PARP and cleaved-caspase-3. In addition, the properties of DOX-induced cancer cell (DLD-1 cells) death did not interfere when combined GS and DOX. CONCLUSION: These data provide considerable evidence that GS could serve as a novel cardioprotective agent against DOX-induced cardiotoxicity.     

艾叶提取物在减轻DOX诱导的心肌细胞损伤中的作用和机制

目的 探讨艾叶提取物(Artemisiaargyiextract,AAE)对DOX(doxorubicin,Dox)诱导心肌细胞损伤的影响.方法 选择不同剂量的艾叶提取物(0.5、1、3g/ml)处理经DOX预处理的大鼠心肌细胞H9C2细胞,MTT法检测细胞存活率,Hoechst检测细胞凋亡,免疫荧光检测p65的入核情...     

依达拉奉通过调控p38MAPK通路抑制阿霉素的心肌毒性

目的探讨新型抗氧化剂依达拉奉（edaravone,EDA）能否通过调控p38丝裂原激活蛋白激酶（mitogen．acti—ratedproteinkinase,MAPK）通路保护H9c2心肌细胞对抗阿霉素（doxombicin,DOX）引起的损伤。方法应用5~mol／LDOX处理H9c2心肌24h以建立心肌毒性损伤模型。CCK一8比色法检测细胞存活率;双氯荧光素（DCFH—DA）染色荧光显微镜照像测定细胞内活性氧（reactiveoxygenspecies,ROX）水平;罗丹明123（rhl23）染色荧光显微镜照像检测线粒体膜电位（mitochondrialmembranepotential,MMP）;Westernblot法测定p38MAPK蛋白表达水平。结果在15～60min的时间范围内,5p．mol／LDOX呈时间依赖性地上调磷酸化（phosphorylated,P）p38MAPK表达。在DOX处理心肌细胞前,应用40~mol／LEDA预处理60min不仅能抑制DOX对p-p38MAPK表达的上调作用,也能抑制DOX引起的心肌细胞损伤,使细胞存活率升高、胞内ROS生成减少及MMP丢失减少。另方面,应用了31~mol／LSB203580（p38MAPK抑制剂）预处理60min也产生类似于上述的EDA对抗DOX心肌毒性的作用。结论EDA可通过抑制p38MAPK通路保护H9c2心肌细胞对抗DOX引起的损伤。     

刺梨黄酮对阿霉素所致心肌细胞毒性的保护作用

目的 探讨刺梨黄酮（FRRT）对阿霉素（DOX)所致心肌细胞凋亡的影响及机制。 方法 利用1~3 d新生大鼠（每次26只）原代分离培养心肌细胞和H9C2心肌细胞系,5 μmol/L DOX孵育心肌细胞,建立心肌细胞毒性模型,并用FRRT干预,透射电子显微镜观察各组H9C2心肌细胞株超微结构。利用免疫荧光技术和Western blotting检测Bax、P53和Bcl-2蛋白的表达,并对Western blotting检测结果进行半定量分析。 结果 透射电子显微镜观察显示,DOX组细胞内呈现大量的自噬泡和脂褐素, 细胞状态差;FRRT干预后,心肌细胞未见脂褐素的结构,有少量自噬泡。免疫荧光检测显示,DOX组Bax和P53呈阳性表达,Bcl-2呈弱阳性表达;FRRT+DOX组Bax和P53表达不明显,Bcl-2呈强阳性表达。Western blotting检测结果显示,5 μmol/L DOX孵育心肌细胞18 h时,Bax蛋白表达水平达到最高,组间比较,差异有统计学意义（P<0.01）。Bax蛋白在DOX组表达增加,FRRT+DOX组表达减少,组间比较,差异具有统计学意义（P<0.05）;P53蛋白在DOX组表达增加,FRRT+DOX组表达减少,组间比较,差异无统计学意义（P>0.05）;Bcl-2蛋白在DOX组表达减少,FRRT+DOX组表达增加,组间比较,差异具有统计学意义（P<0.05,P<0.01）。 结论 FRRT通过下调DOX引起的心肌细胞凋亡作用,进而发挥对心肌细胞的保护作用。     

Synthetic liver X receptor agonist T0901317 attenuates high glucose-induced oxidative stress,mitochondrial damage and apoptosis in cardiomyocytes

The aim of the present study was to investigate the protective effects of T0901317 (T0), a potent agonist of liver X receptors (LXRs), on high glucose-induced oxidative stress and apoptosis in H9c2 cardiac cells. Exposure of H9c2 cells to high glucose alone, not only caused a significant increase in apoptosis and reactive oxygen species (ROS) generation, but also led to a decrease in mitochondrial membrane potential (ΔΨm), release of cytochrome c, decrease in Bcl-2, increase in Bax expression and the activation of caspase-3, caspase-9, poly (ADP-ribose) polymerase (PARP) and nuclear factor (NF)-κB. However, pretreatment with T0 effectively decreased apoptosis, reduced the levels of ROS, abrogated ΔΨm, inhibited cytochrome c release and NF-κB activation, increased Bcl-2 and decreased Bax expression. In conclusion, our data suggest that T0 exerts protective effects against high glucose-induced apoptosis in H9C2 cardiac muscle cells via inhibition of ROS production, mitochondrial death and NF-κB activation.     

Overexpression of angiopoietin-1 reduces doxorubicin-induced apoptosis in cardiomyocytes

Doxorubicin(Dox) is a major anticancer chemotherapeutic agent.However,it causes cardiomyopathy due to the side effect of cardiomyocyte apoptosis.We have previously reported that angiopoietin-1 significantly reduced myocardial infarction after ischemic injury and protected cardiomyocytes from oxidative stress-induced apoptosis.It is hypothesized that angiopoietin-1 may protect cardiomyocytes from Dox-induced apoptosis.Cardiomyocytes H9C2 were transfected with adenovirus expressing angiopoietin-1(Ad5-Ang-1) 24 h before the cells were challenged with Dox at a concentration of 2 μmol/L.Ad5-GFP served as the vector control.Cardiomyocyte apoptosis was evaluated using Annexin V-FITC staining and caspase-3 and caspase-8 activity was determined by Western blotting.The results showed that Dox treatment significantly induced cardiomyocyte apoptosis as evidenced by the greater number of Annexin V-FITC stained cells and increases in caspase-3 and caspase-8 activity.In contrast,overexpression of angiopoietin-1 significantly prevented Dox-induced cardiomyocyte apoptosis.To elucidate the mechanisms by which angiopoietin-1 protected cells from Dox-induced apoptosis,we analyzed both extrinsic and intrinsic apoptotic signaling pathways.We observed that angiopoietin-1 prevented Dox-induced activation of both extrinsic and intrinsic apoptotic signaling pathways.Specifically,angiopoietin-1 prevented DOX-induced increases in FasL and Bax levels and cleaved caspase-3 and caspase-8 levels in H9C2 cells.In addition,overexpression of angiopoietin-1 also activated the pro-survival phosphoinositide-3 kinase(PI3K)/Akt signaling pathway and decreased Dox-induced nuclear factor-kappaB(NF-κB) activation.Our data suggest that promoting the expression of angiopoietin-1 could be a potential approach for reducing Dox-induced cardiomyocyte cytoxicity.     

Cardiomyocyte death in doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is one of the most widely used and successful antitumor drugs, but its cumulative and dose-dependent cardiac toxicity has been a major concern of oncologists in cancer therapeutic practice for decades. With the increasing population of cancer survivors, there is a growing need to develop preventive strategies and effective therapies against DOX-induced cardiotoxicity, in particular late-onset cardiomyopathy. Although intensive investigations on DOX-induced cardiotoxicity have continued for decades, the underlying mechanisms responsible for DOX-induced cardiotoxicity have not been completely elucidated. A rapidly expanding body of evidence supports the notion that cardiomyocyte death by apoptosis and necrosis is a primary mechanism of DOX-induced cardiomyopathy and that other types of cell death, such as autophagy and senescence/aging, may participate in this process. This review focuses on the current understanding of the molecular mechanisms underlying DOX-induced cardiomyocyte death, including the major primary mechanism of excess production of reactive oxygen species (ROS) and other recently discovered ROS-independent mechanisms. The different sensitivities to DOX-induced cell death signals between adult and young cardiomyocytes will also be discussed.     

Effect of hypothermia on doxorubicin-induced cardiac myoblast signaling and cell death

BackgroundAnthracyclines (AC) are useful chemotherapeutic agents whose principal limitation is cardiac toxicity, which may progress to heart failure, transplantation or even death. We have shown that this toxicity involves oxidative stress-induced activation of the DNA damage pathway. Hypothermia has been shown to be protective against other diseases involving oxidative stress but has not been studied in models of AC toxicity.MethodsIn the current experiments, H9C2 cardiac myoblasts were treated with varying concentrations of the AC doxorubicin (DOX) during normothermia (37°C) or mild hypothermia (35°C). Total cell death was assayed using trypan blue exclusion and apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine-biotin nick end labeling (TUNEL) staining. Oxidative stress was assayed using the fluorescent indicator 2′7′-dichlorofluorescein diacetate. DNA damage pathway activation was assayed by immunostaining for H2AX and p53. Mitochondrial membrane potential was assayed by JC-1 staining.ResultsAt all concentrations of DOX examined (1, 2.5 and 5 μM), hypothermia reduced oxidative stress, activation of H2AX and p53, loss of mitochondrial membrane potential and total and apoptotic cell death (P=.001–.03 for each observation).ConclusionsThe reduction of oxidative stress-induced activation of the DNA damage pathway and consequent cell death by mild hypothermia supports a possible protective role to reduce the clinical impact of DOX-induced cardiac toxicity. Such an approach may allow expanded use of these effective chemotherapeutic agents to increase cancer cure rates.     

阿霉素诱导心肌细胞死亡机制

阿霉素是目前最为有效的抗肿瘤药物之一,其主要的严重副作用是累积性、剂量依赖性的心肌毒性反应,可进一步发展成不可逆性心肌损伤,最终导致充血性心力衰竭.心肌细胞凋亡和坏死被认为是阿霉素诱导心肌病变发展过程中的主要因素,自我吞噬和细胞老化等其他细胞死亡方式也参与此过程.阿霉素诱导心肌细胞死亡的机制可能包括:氧化应激以及由此发...     

Cyclic Adenosine Monophosphate Inhibits Nitric Oxide‐Induced Apoptosis of Cardiac Muscle Cells in a c‐Jun N‐Terminal Kinase‐Dependent Manner

Cyclic adenosine monophosphate (cAMP) modulates various agent‐induced apoptosis. In this study, we observed that cAMP had a significantly protective effect on nitric oxide (NO)‐induced cytotoxicity in H9c2 cardiac muscle cells. Pretreatment with DBcAMP (cAMP analogue) or forskolin (adenylyl cyclase activator) also significantly prevented the SNP‐induced apoptosis in H9c2 cells. In contrast, H‐89 or KT5720 (PKA inhibitor) reversed the protective effects of DBcAMP. In this study, DBcAMP or forskolin reduced SNP‐induced JNK/SAPK activation to the basal level, but KT5720 reversed the inhibitory effects of these two agents. In contrast to JNK/SAPK activation, DBcAMP and forskolin significantly enhanced SNP‐activated p38 MAPK phosphorylation and did not affect SNP‐mediated ERK activation. KT5720 reversed the effects of DBcAMP and forskolin on p38 MAPK phosphorylation. The inhibition of the JNK pathway by transfection of a dominant negative mutant of JNK/SAPK markedly reduced the extent of SNP‐induced cell death. Taken together, we suggest that JNK/SAPK is related to cAMP‐protective effect in SNP‐induced apoptosis. In addition, c‐AMP relating agents protected SNP‐induced cell death in neonatal rat ventricular cardiomyocytes. The cAMP‐relating agent‐induced protective effect is not resricted in H9c2 cardiac muscle cells.     

Cyclic adenosine monophosphate inhibits nitric oxide-induced apoptosis of cardiac muscle cells in a c-Jun N-terminal kinase-dependent manner

Cyclic adenosine monophosphate (cAMP) modulates various agent-induced apoptosis. In this study, we observed that cAMP had a significantly protective effect on nitric oxide (NO)-induced cytotoxicity in H9c2 cardiac muscle cells. Pretreatment with DBcAMP (cAMP analogue) or forskolin (adenylyl cyclase activator) also significantly prevented the SNP-induced apoptosis in H9c2 cells. In contrast, H-89 or KT5720 (PKA inhibitor) reversed the protective effects of DBcAMP. In this study, DBcAMP or forskolin reduced SNP-induced JNK/SAPK activation to the basal level, but KT5720 reversed the inhibitory effects of these two agents. In contrast to JNK/SAPK activation, DBcAMP and forskolin significantly enhanced SNP-activated p38 MAPK phosphorylation and did not affect SNP-mediated ERK activation. KT5720 reversed the effects of DBcAMP and forskolin on p38 MAPK phosphorylation. The inhibition of the JNK pathway by transfection of a dominant negative mutant of JNK/SAPK markedly reduced the extent of SNP-induced cell death. Taken together, we suggest that JNK/SAPK is related to cAMP-protective effect in SNP-induced apoptosis. In addition, c-AMP relating agents protected SNP-induced cell death in neonatal rat ventricular cardiomyocytes. The cAMP-relating agent-induced protective effect is not resricted in H9c2 cardiac muscle cells.     

小檗碱增强阿霉素诱导的膀胱癌T24细胞凋亡

 目的:研究小檗碱对阿霉素诱导的膀胱癌T24细胞凋亡的影响及机制。方法:将膀胱癌T24细胞分为对照组、阿霉素组、阿霉素+小檗碱组和小檗碱组。采用CCK-8试剂盒测定膀胱癌T24细胞的增殖抑制率。采用Hoechst 33258染色剂检测细胞凋亡,同时测定caspase-3和caspase-9活性以及Bcl-2、Bax蛋白的表达。结果:小檗碱呈剂量和时间依赖性地促进阿霉素诱导的T24细胞凋亡。与阿霉素组比较,小檗碱+阿霉素组caspase-3、caspase-9活性和Bax蛋白的表达水平明显增加,而Bcl-2蛋白表达水平降低。结论:小檗碱可进一步增强阿霉素对T24细胞增殖的抑制作用,其机制与小檗碱增强阿霉素诱导的T24细胞凋亡有关。     

紫草素减轻低氧-复氧致大鼠心肌细胞系H9c2损伤

目的探索紫草素对低氧-复氧(H/R)损害的H9c2心肌细胞的保护作用。方法将心肌细胞系H9c2分为对照组、H/R组、紫草素(0. 1、1和10μmol/L)干预组,每组3个平行孔; MTT法检测紫草素对H9c2细胞毒性;流式细胞计量术检测细胞凋亡和周期; DCFH-DA检测细胞活性氧水平;生化检测细胞中MDA、8-OHdG和GSH含量;qPCR检测细胞γ-GCS、HO-1和NQO1 mRNA表达; Western blot检测细胞中Bax、Bcl-2、caspase-3、cleaved caspase-3、Keap1和Nrf2蛋白表达;免疫荧光检测细胞Nrf2蛋白进核情况。结果紫草素呈浓度-时间依赖性抑制H9c2细胞增殖(P<0. 05); H/R诱导H9c2细胞凋亡、细胞周期阻滞及促进Bax及cleaved caspase-3蛋白表达,抑制Bcl-2蛋白表达(P<0. 05),紫草素呈浓度依赖性抑制细胞凋亡、解除细胞周期阻滞及cleaved caspase-3和Bax蛋白表达,增加Bcl-2蛋白表达;紫草素可降低H/R所致活性氧水平、MDA及8-OHdG升高,增高H/R所...     

槲皮素通过抑制蛋白酶体活性减轻心肌细胞肥大

目的:探讨槲皮素对血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)诱导的心肌细胞肥大的防治作用及机制。方法:分别在原代新生大鼠心肌细胞和培养的H9c2心肌细胞,用100 nmol/L的AngⅡ诱导心肌细胞肥大模型,并给予3种不同浓度的槲皮素(10μmol/L,20μmol/L,40μmol/L)处理,利用免疫荧光检测原代和H9c2心肌细胞表面积的改变,采用荧光底物法检测H9c2心肌细胞蛋白酶体的活性变化,以及用Western blot检测H9c2心肌细胞糖原合酶激酶(GSK)-3α/β、Akt及其磷酸化情况。结果:与对照组相比,模型组原代心肌细胞和H9c2心肌细胞表面积均显著增大,槲皮素处理组2种心肌细胞表面积较模型组均明显减小,而20μmol/L槲皮素组减小更明显(P0.05)。在H9c2细胞实验中发现模型组蛋白酶体的糜蛋白酶样、半胱天冬酶样和胰蛋白酶样活性明显升高,20μmol/L和40μmol/L槲皮素组半胱天冬酶样和胰蛋白酶样活性较模型组均明显降低,而糜蛋白酶样活性只有在槲皮素20μmol/L时有显著差异(P0.05);Western blot检测结果显示,模型组磷酸化(p)-GSK-3α、p-GSK-3β和p-Akt水平较对照组均明显增加,而20μmol/L和40μmol/L槲皮素处理均使p-GSK-3α、p-GSK-3β和p-Akt水平明显下降(P0.05)。结论:槲皮素可明显抑制蛋白酶体活性从而减轻心肌细胞肥大,其机制可能是通过下调Akt活性而升高GSK-3α/β活性实现的。     

Doxorubicin-induced cardiotoxicity involves IFNγ-mediated metabolic reprogramming in cardiomyocytes

Immune responses contribute to a large extent to heart diseases. However, it is still not clear how the key inflammatory mediator interferon-γ (IFNγ) plays a role in doxorubicin (DOX)-induced cardiomyopathy. We report here that DOX-induced heart dysfunction involves IFNγ signaling in mice. The IFNγ receptor was found to be highly expressed on cardiomyocytes, and its downstream signaling was activated in heart tissues upon DOX treatment. In vitro, IFNγ strongly aggravated the injury of cardiomyocytes exposed to DOX. Although not affecting DOX-induced cell death, IFNγ disrupted mitochondrial respiration and fatty acid oxidation in DOX-exposed cardiomyocytes. IFNγ extended the suppression of the AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) axis by DOX to a p38-dependent branch. Activation of AMPK or inhibition of p38 inhibited the enhancing effect of IFNγ on the DOX-induced cardiotoxicity and prolonged the survival time in DOX-treated mice. Taken together, our results indicate that reprogramming of cardiac metabolism by IFNγ represents a previously unidentified key step for DOX-induced cardiomyopathy. This unavoidable impact of IFNγ on cardiomyocyte metabolism during chemotherapy redirects our attention to the balance between beneficial immunosurveillance of cancer cells and unwanted toxic side-effects. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Doxorubicin-induced chronic dilated cardiomyopathy—the apoptosis hypothesis revisited

The chemotherapeutic agent doxorubicin (DOX) has significantly increased survival rates of pediatric and adult cancer patients. However, 10% of pediatric cancer survivors will 10–20 years later develop severe dilated cardiomyopathy (DCM), whereby the exact molecular mechanisms of disease progression after this long latency time remain puzzling. We here revisit the hypothesis that elevated apoptosis signaling or its increased likelihood after DOX exposure can lead to an impairment of cardiac function and cause a cardiac dilation. Based on recent literature evidence, we first argue why a dilated phenotype can occur when little apoptosis is detected. We then review findings suggesting that mature cardiomyocytes are protected against DOX-induced apoptosis downstream, but not upstream of mitochondrial outer membrane permeabilisation (MOMP). This lack of MOMP induction is proposed to alter the metabolic phenotype, induce hypertrophic remodeling, and lead to functional cardiac impairment even in the absence of cardiomyocyte apoptosis. We discuss findings that DOX exposure can lead to increased sensitivity to further cardiomyocyte apoptosis, which may cause a gradual loss in cardiomyocytes over time and a compensatory hypertrophic remodeling after treatment, potentially explaining the long lag time in disease onset. We finally note similarities between DOX-exposed cardiomyocytes and apoptosis-primed cancer cells and propose computational system biology as a tool to predict patient individual DOX doses. In conclusion, combining recent findings in rodent hearts and cardiomyocytes exposed to DOX with insights from apoptosis signal transduction allowed us to obtain a molecularly deeper insight in this delayed and still enigmatic pathology of DCM.     

MicroRNA-34a靶向SIRT1参与阿霉素诱导的心肌细胞凋亡

目的:研究微小RNA-34a(microRNA-34a,miR-34a)在阿霉素诱导的心肌细胞凋亡中的作用及其作用靶基因。方法:建立阿霉素(doxorubicin,Dox)诱导的大鼠H9c2心肌细胞凋亡模型;TUNEL染色观察H9c2细胞凋亡;双萤光素酶报告实验检测miR-34a与潜在靶基因沉默信息调节因子1(silent information regulator 1,SIRT1)3'端非翻译区(3'-untranslated region,3'UTR)的结合作用;实时荧光定量PCR检测miR-34a和SIRT1 mRNA表达水平,Western blot检测SIRT1和凋亡相关蛋白表达水平。结果:阿霉素处理H9c2细胞之后,细胞发生凋亡,miR-34a的表达显著增强;双萤光素酶报告实验提示miR-34a与SIRT1 3'UTR可相互作用,并证实miR-34a可在转录后水平抑制SIRT1的表达,SIRT1蛋白水平在阿霉素处理的心肌细胞中显著下调;过表达miR-34a及沉默SIRT1均能一致性抑制Bcl-2表达,促进Bax和p66shc的表达,而过表达SIRT1能有效抑制阿霉素诱导的H9c2细胞凋亡。结论:SIRT1是miR-34a的靶基因,并介导了miR-34a在阿霉素诱导的心肌细胞凋亡中的作用。