Analysis of the potential biological value of pyruvate dehydrogenase E1 subunitβin human cancer

BACKGROUND The pyruvate dehydrogenase E1 subunitβ(PDHB)gene which regulates energy metabolism is located in mitochondria.However,few studies have elucidated the role and mechanism of PDHB in different cancers.AIM To comprehensive pan-cancer analysis of PDHB was performed based on bioinformatics approaches to explore its tumor diagnostic and prognostic value and tumor immune relevance in cancer.In vitro experiments were performed to examine the biological regulation of PDHB in liver cancer.METHODS Pan-cancer data related to PDHB were obtained from the Cancer Genome Atlas(TCGA)database.Analysis of the gene expression profiles of PDHB was based on TCGA and Genotype Tissue Expression Dataset databases.Cox regression analysis and Kaplan-Meier methods were used to assess the correlation between PDHB expression and survival prognosis in cancer patients.The correlation between PDHB and receiver operating characteristic diagnostic curve,clinicopathological staging,somatic mutation,tumor mutation burden(TMB),microsatellite instability(MSI),DNA methylation,and drug susceptibility in pan-cancer was also analyzed.Various algorithms were used to analyze the correlation between PDHB and immune cell infiltration and tumor chemotaxis environment,as well as the co-expression analysis of PDHB and immune checkpoint(ICP)genes.The expression and functional phenotype of PDHB in single tumor cells were studied by single-cell sequencing,and the functional enrichment analysis of PDHB-related genes was performed.The study also validated the level of mRNA or protein expression of PDHB in several cancers.Finally,in vitro experiments verified the regulatory effect of PDHB on the proliferation,migration,and invasion of liver cancer.RESULTS PDHB was significantly and differently expressed in most cancers.PDHB was significantly associated with prognosis in patients with a wide range of cancers,including kidney renal clear cell carcinoma,kidney renal papillary cell carcinoma,breast invasive carcinoma,and brain lower grade glioma.In some cancers,PDHB expression was clearly associated with gene mutations,clinicopathological stages,and expression of TMB,MSI,and ICP genes.The expression of PDHB was closely related to the infiltration of multiple immune cells in the immune microenvironment and the regulation of tumor chemotaxis environment.In addition,single-cell sequencing results showed that PDHB correlated with different biological phenotypes of multiple cancer single cells.This study further demonstrated that down-regulation of PDHB expression inhibited the proliferation,migration,and invasion functions of hepatoma cells.CONCLUSION As a member of pan-cancer,PDHB may be a novel cancer marker with potential value in diagnosing cancer,predicting prognosis,and in targeted therapy.

New insights into the pathogenesis of primary biliary cholangitis asymptomatic stage

Primary biliary cholangitis(PBC)is a chronic cholestatic progressive liver disease and one of the most important progressive cholangiopathies in adults.Damage to cholangiocytes triggers the development of intrahepatic cholestasis,which progresses to cirrhosis in the terminal stage of the disease.Accumulating data indicate that damage to biliary epithelial cells[(BECs),cholangiocytes]is most likely associated with the intracellular accumulation of bile acids,which have potent detergent properties and damaging effects on cell membranes.The mechanisms underlying uncontrolled bile acid intake into BECs in PBC are associated with pH change in the bile duct lumen,which is controlled by the bicarbonate(HCO3-)buffer system“biliary HCO3-umbrella”.The impaired production and entry of HCO3-from BECs into the bile duct lumen is due to epigenetic changes in expression of the X-linked microRNA 506.Based on the growing body of knowledge on the molecular mechanisms of cholangiocyte damage in patients with PBC,we propose a hypothesis explaining the pathogenesis of the first morphologic(ductulopenia),immunologic(antimitochondrial autoantibodies)and clinical(weakness,malaise,rapid fatigue)signs of the disease in the asymptomatic stage.This review focuses on the consideration of these mechanisms.

Catalytic domain of PDC-E2 contains epitopes recognized by antimitochondrial antibodies in primary biliary cirrhosis

AIM:To search for further immunodominant peptides of the pyruvate dehydrogenase complex E2-component (PDC-E2) recognized by antimitochondrial antibodies (AMA) in primary biliary cirrhosis (PBC). METHODS:Sera from 95 patients with PBC were tested by enzyme-linked immunosorbent assay against 33 synthetic overlapping peptides (25 amino acids; aa) covering the entire length of the E2-subunit of PDC-E2. Furthermore,the inner lipoyl peptide 167-184 was used in an unlip oylated and a lipoylated form as well as coupled to ovalbumin. Sera from 11 AMA negative/ANA posit ive PBC patients,63 patients with other liver disorders and 22 healthy blood donors served as controls.RESULTS:Of the 95 PBC-sera,74% reacted with the peptide 475-499 and 58% with the pept ide 407-431 located within the catalytic domain of PDC-E2. Patients with other disorders or healthy controls were positive in only up to 18%. Antibodies to the unlipoylatedand lip oylated pept ide 167-184 within the inner lipoyl domain were found in only 5% and 11% of the PBC sera,respectively; using ovalbumin-coupled peptides,the incidence increased up to 57% (unlipoylated form). CONCLUSION:Peptides within the catalytic site of PDC-E2 rather than the previously reported lipoyl binding peptide 167-184 may represent major immunodomin ant epitopes recognized by AMA in PBC.

高通量测序揭示原发性胆汁性胆管炎患者的T细胞受体图谱特征

目的揭示原发性胆汁性胆管炎(primary biliary cholangitis,PBC)患者T细胞受体(T cell receptor,TCR)图谱特征,并揭示大肠埃希菌(Escherichia coli,E.coli)的丙酮酸脱氢酶复合体E2亚基(pyruvate dehydrogenase complex E2,PDC-E2)抗原在PBC疾病的分子模拟机制。方法采用多重聚合酶链反应和免疫组库测序技术分析PBC患者和健康对照者的CD4^(+)和CD8^(+)记忆性TCRβ链互补决定区3(complementarity determining region 3,CDR3)序列的多样性、氨基酸组成及疏水性、共有CDR3序列。体外诱导和扩增人PDC-E2_(163-176)(人PDC-E2)抗原相关T细胞和E.coli PDC-E2_(31-44/134-147/235-248)(E.coli PDC-E2)抗原相关T细胞,通过免疫组库测序技术鉴定人(和E.coli)PDC-E2抗原相关TCRβCDR3图谱,并分析其丰度变化。结果PBC患者组和健康对照组间的CD4^(+)记忆性T细胞、CD8^(+)记忆性T细胞TCRβCDR3免疫图谱多样性相似,D50指数[CD4^(+)记忆性T细胞:0.028±0.019比0.034±0.015;CD8^(+)记忆性T细胞:(1.86±2.70)×10^(-3)比(4.62±3.89)×10^(-4)]、Shannon指数(CD4^(+)记忆性T细胞:9.473±1.346比9.734±0.933;CD8^(+)记忆性T细胞:6.197±1.519比5.436±1.629)、Gini指数(CD4^(+)记忆性T细胞:0.786±0.048比0.760±0.036;CD8^(+)记忆性T细胞:0.920±0.047比0.939±0.025)等差异均无统计学意义(P均>0.05)。PBC组和健康对照组CD4^(+)记忆性T细胞和CD8^(+)记忆性T细胞间共有CDR3序列百分比差异无统计学意义[(6.47±1.43)%比(6.21±3.18)%;t=-0.21,P=0.84]。健康对照组和PBC组中序列长度为13、14、15的CDR3分子第6位和第7位氨基酸的组成频率中部分存在显著差异,疏水氨基酸组成频率近似。通过细胞培养和免疫组库测序鉴定了一系列人PDC-E2和E.coli PDC-E2抗原刺激后丰度显著上升的TCR序列。结论该研究鉴定出PBC疾病的TCR图谱特征,从TCR这个新视角阐述了E.coli在PBC疾病中的分子模拟机制。

Xenobiotics and loss of tolerance in primary biliary cholangitis

Data from genome wide association studies and geoepidemiological studies established that a com-bination of genetic predisposition and environmental stimulation is required for the loss of tolerance in primary biliary cholangitis(PBC).The serologic hallmark of PBC are the presence of high titer anti-mitochondrial autoantibodies(AMA)that recognize the lipoyl domain of the mitochondrial pyruvate dehydrogenase E2(PDC--E2)subunit.Extensive efforts have been directed to investigate the molecular basis of AMA.Recently,experimental data has pointed to the thesis that the breaking of tolerance to PDC--E2 is a pivotal event in the initial etiology of PBC,including environmental xenobiotics including those commonly found in cos-metics and food additives,suggesting that chemical modification of the PDC--E2 epitope may render its vulnerable to become a neo-antigen and trigger an immune response in genetically susceptible hosts.Here,we will discuss the natural history,genetics and immunobiology of PBC and structural constraints of PDC--E2 in AMA recognition which makes it vulnerable to chemical modification.

丙酮酸脱氢酶E1α亚单位缺陷导致Leigh综合征

Leigh综合征是由于线粒体呼吸链能量代谢障碍所导致的遗传性疾病,丙酮酸脱氢酶E1浕亚单位(pyruvate dehydrogenase complex E1 alpha subunit,PDHA1)缺陷是导致Leigh综合征的常见原因之一。该研究通过PDHA1基因分析首次确诊了1例中国患者。该患儿1岁后运动发育落后,无力,肌张力低下,肌腱反射消失,发热、感冒时间歇性加重,智力发育正常。肌电图检查、腓肠肌病理活检结果提示神经性损害。3岁时脑MRI扫描未见异常,5岁时脑MRI呈现双侧苍白球对称性损害,符合Leigh综合征表现。经基因分析证实患者及其母亲PDHA1基因外显子3存在C214T突变,导致丙酮酸脱氢酶复合物活性下降。经过维生素B1、辅酶Q10、左旋肉碱及低碳水化合物饮食治疗后,患儿运动能力显著改善,现在8岁,正常就学。PDHA1缺陷为X连锁遗传性疾病,表型复杂,临床诊断困难,该患儿以无力为主要表现,经基因诊断确诊。

非诺贝特对2型糖尿病大鼠骨骼肌丙酮酸脱氢酶激酶表达的影响

目的:动态观察2型糖尿病进展过程中骨骼肌丙酮酸脱氢酶激酶(PDK4)和丙酮酸脱氢酶1α亚单位(E1α)水平的变化和非诺贝特的干预作用。方法:4周龄自发性2型糖尿病动物模型雄性OLETF大鼠20只随机分为治疗组和未治组,每组10只,另设正常LETO大鼠10只为对照。治疗组每d灌胃非诺贝特20mg/kg,未治组和对照组每d灌胃等量蒸馏水。分别于第8周、17周和30周龄称体质量,行标准葡萄糖耐量试验(OGTT),测定空腹血糖和胰岛素、2h血糖、甘油三酯和胆固醇。17周龄时每组随机抽取4只动物杀检,至30周龄全部杀检,取下肢骨骼肌,Western blot测定骨骼肌PDK4和E1α的表达。结果:8周龄时3组生化指标差异无统计学意义(P>0.05)。随鼠龄的增加,未治组2h血糖、PDK4和E1α的表达高于同期对照组;与未治组比较,治疗组上述指标改善不明显(P>0.05)。结论:胰岛素抵抗大鼠骨骼肌PDK4和E1α的表达随病程增加持续增强,这可能与胰岛素在骨骼肌的作用下降有关。

Sdha基因敲低对小鼠肝细胞BNL CL.2细胞增殖、细胞周期和凋亡的影响

目的探讨琥珀酸脱氢酶复合物亚单位A(SDHA)对小鼠肝细胞BNL CL.2细胞增殖、细胞周期和凋亡的影响。方法用慢病毒载体介导的sh RNA敲低BNL CL.2细胞中sdha基因的表达。流式细胞仪检测慢病毒的感染效率;实时荧光定量PCR和Western蛋白印迹法分别检测sdha m RNA和SDHA蛋白表达水平;细胞计数法检测细胞增殖;流式细胞术检测细胞凋亡和细胞周期。结果无相关sh RNA对照组和sdha sh RNA组慢病毒的感染效率均>80%。与无相关sh RNA对照组相比,感染sdha sh RNA慢病毒载体的BNL CL.2细胞sdha m RNA水平降低20倍左右(P<0.01),蛋白表达水平降低10倍左右(P<0.01);细胞增殖速度减慢,为无相关sh RNA对照组的70%左右(P<0.05);细胞周期发生改变,G0/G1期细胞百分率是无相关sh RNA对照组的1.17倍(P<0.01),G2/M期细胞百分率为1.37倍(P<0.01),S期细胞百分率为73.8%(P<0.01);但细胞凋亡率无明显差异。结论降低SDHA表达对小鼠肝细胞BNL CL.2细胞增殖有明显的抑制作用,其抑制作用与细胞周期阻滞相关,与细胞凋亡无明显关系。

原发性胆汁性肝硬化患者血清AMA-M2及其靶抗原检测的阳性率对比

目的:针对PBC患者血清同时选用国产和进口两种试剂盒检测AMA-M2及其靶抗原:丙酮酸脱氢酶复合体E2亚单位(PDC-E2)及抗M2-3E等免疫指标,并对其敏感性进行对比,观察两种试剂盒检测有无差异及3个指标之间的敏感性。方法:对51例PBC确诊患者的血清标本,采用上海丰翔生物公司及欧蒙公司的ELISA试剂盒对待测血清分别进行了AMA-M2、抗M2-3E、PDC-E2等指标的检测,进行阳性率的比较。结果:51例患者血清标本中,国产试剂盒检测AMA-M2、抗M2-3E、PDC-E2的阳性率分别为72.5%、90.2%、72.5%,进口试剂盒检测AMA-M2、抗M2-3E、PDC-E2的阳性率分别为78.4%、92.2%、82.4%,经统计软件处理得到的结果P>0.05,无明显的统计学差异。针对42例AMA阳性的患者进行AMA-M2、抗M2-3E、PDC-E2检测时,国产试剂盒检测的阳性率分别为85.7%、95.2%和78.6%,进口试剂盒检测的阳性率分别为95.2%、100%、95.2%,经统计软件处理后得出P>0.05,两种试剂盒检测无明显的差别。结论:使用进口和国产两种试剂盒检测AMA-M2、PDC-E2、抗M2-3E的阳性率无明显的统计学差异。AMA-M2、PDC-E2、抗M2-3E 3个指标中阳性率最高的是抗M2-3E,AMA-M2和PDC-E2差异无统计学意义。

Dichloroacetic acid and rapamycin synergistically inhibit tumor progression

Mammalian target of rapamycin(mTOR)controls cellular anabolism,and mTOR signaling is hyperactive in most cancer cells.As a result,inhibition of mTOR signaling benefits cancer patients.Rapamycin is a US Food and Drug Administration(FDA)-approved drug,a specific mTOR complex 1(mTORC1)inhibitor,for the treatment of several different types of cancer.However,rapamycin is reported to inhibit cancer growth rather than induce apoptosis.Pyruvate dehydrogenase complex(PDHc)is the gatekeeper for mitochondrial pyruvate oxidation.PDHc inactivation has been observed in a number of cancer cells,and this alteration protects cancer cells from senescence and nicotinamide adenine dinucleotide(NAD^(+))exhaustion.In this paper,we describe our finding that rapamycin treatment promotes pyruvate dehydrogenase E1 subunit alpha 1(PDHA1)phosphorylation and leads to PDHc inactivation dependent on mTOR signaling inhibition in cells.This inactivation reduces the sensitivity of cancer cells'response to rapamycin.As a result,rebooting PDHc activity with dichloroacetic acid(DCA),a pyruvate dehydrogenase kinase(PDK)inhibitor,promotes cancer cells'susceptibility to rapamycin treatment in vitro and in vivo.

鹿骨粉对卵巢摘除大鼠心肌细胞HK-2和PDHc表达的影响

目的探讨鹿骨粉对卵巢摘除大鼠心肌组织中HK-2和PDHc表达和心肌结构的影响。方法对Wistar大鼠行双侧卵巢摘除术后,将大鼠随机分为假手术(Sham)组、模型(Model)组、鹿骨粉不同剂量(SBP200、400及800 mg/kg)组。术后即刻给予鹿骨粉组大鼠相应剂量的鹿骨粉,每天1次,连续给药4个月后,处死各组大鼠,取出心脏,HE染色观察心肌结构,免疫组织化学染色检测HK-2和PDHc的蛋白表达情况。结果与Model组比较,SBP各组心肌组织中HK-2和PDHc蛋白表达均成增多趋势,心肌细胞核大小适中,染色较淡,细胞排列整齐,形态正常。结论鹿骨粉能够促进卵巢摘除后心肌细胞中HK-2和PDHc蛋白表达增高,维持心肌结构完整,对心脏具有保护作用。