抗肿瘤药治疗新靶点——Na＋-H＋交换器及其抑制剂研究进展 抗肿瘤药治疗新靶点——Na＋-H＋交换器及其抑制剂研究进展

Na＋-H＋交换器是一类普遍存在于真核细胞膜上的离子交换蛋白,可介导胞外钠离子和胞内氢离子的交换,与肿瘤生长、代谢、血管新生以及多药耐药等密切相关,故有望成为抗肿瘤药物开发的新靶点。介绍了Na＋-H＋交换器基本原理及其抑制剂研究进展,旨在为抗肿瘤新药的开发拓宽思路并提供参考。     

TF3-H4对CD4~+CD25~+调节性T细胞和CD4~+CD25~-效应性T细胞早期活化的影响

目的观察1',2',3',7'-四氢茶黄素-3,3'-双没食子酸酯(TF3-H4)对CD4+CD25+调节性T细胞和CD4+CD25-效应性T细胞早期活化的影响,分析TF3-H4对两群功能相反的CD4+T细胞的作用。方法免疫磁珠分离BALB/c小鼠脾脏CD4+CD25+调节性T细胞和CD4+CD25-效应性T细胞,加入ConA或PDB,和TF3-H4共同孵育12 h后收集细胞,流式细胞仪分析细胞表面早期活化标志CD69的表达。结果在ConA和PDB的作用下,两群细胞早期活化标志CD69的表达均升高。TF3-H4(20 mg.L-1)不能抑制PKC激动剂PDB激活的CD4+CD25-效应性T细胞CD69的表达,却能抑制ConA激活的CD4+CD25-效应性T细胞CD69表达;同时,TF3-H4也能明显抑制ConA激活的CD4+CD25+调节性T细胞的CD69表达。结论茶黄素衍生物TF3-H4可能经由TCR活化途径的上游抑制CD4+CD25-效应性T细胞活化;TF3-H4对CD4+CD25+调节性T细胞和CD4+CD25-效应性T细胞早期活化的抑制作用,可能是该类化合物发挥抗炎、抗肿瘤作用的机制之一。     

潜在治疗靶点:心肌Na+/H+交换器

细胞内pH（pH_i）的变化（如心肌缺血后细胞内酸中毒）对心脏收缩力影响很大,而其作用机制复杂。pH_i反映了碱化与酸化过程的净平衡。控制细胞内酸中毒主要有两种碱化交换器,即Na～+/H～+交换器（NHE）和Na～+-HCO_3～-同向转运（sympOrt）。NHE使质子外流,同时使Na～+内流,这对于缺血所     

心血管疾病的一类新药:Na+/H+交换体抑制药

Na+-H+交换体(Na+/H+exchanger,NHE)是一种重要的交换系统,在正常生理状态下参与胞液pH和细胞容量调节.分子克隆技术已发现6个NHE的异构体(分别为NHE-1至NHE-6),NHE-1在所有体细胞上普通表达[1];在心肌细胞里,NHE-1主要在连结蛋白43近端的插入盘和T管上表达;NHE-1又是唯一在心肌细胞原生质膜上表达的异构体.业已证实,几种心血管疾病的病理生理都涉及到它[1].     

全自动生化分析仪及电解质分析仪检测K~+、Na~+、Cl~-结果比较

目的　对全自动生化分析仪及电解质分析仪检测K+ 、Na+ 、Cl-三种离子的结果进行比较。方法　全自动生化分析仪检测K+ 、Na+ 用酶法、Cl-硫氰酸汞法 ;电解质分析仪检测K+ 、Na+ 、Cl-用离子选择电极法 (ISE) ,然后对结果进行处理。结果　两种方法的重复性好 ,且测定结果差异无显著性 (P >0 .0 5 ) ,抗干扰能力强 ,线性范围宽 ,具有很好的相关性。结论　酶法适用于全自动生化分析仪 ,可大批量测定 ;ISE法适合于急诊检测     

参麦注射液静注对红细胞膜Na+-K+-ATP酶的影响

为了解参脉注射液对患者红细胞(RBC)膜Na+-K+-ATP酶的影响,本研究随机选择级择期上腹部手术男性患者60例,根据参脉给药剂量的不同,随机分为三组,每组20例Ⅰ组、Ⅱ组和Ⅲ组剂量分别为40,60,80 mg/kg.给药后10,20,30min时测定各组患者静脉血红细胞膜Na+-K+-ATP酶活性,各组患者血压、心率、氧饱和度的变化也同时被记录.结果发现参脉注射液对RBC膜Na+-K+-ATP酶活性具有短暂的抑制作用,当参脉注射液输液量为80 mg/kg时对心率也存在短暂的减慢作用.     

肿瘤细胞内pH值改变与肿瘤多药耐药的关系

细胞内pH值(pHi)增高是许多耐药肿瘤的共同特点,其结果引起肿瘤细胞对化疗药物的敏感性下降,降低药物疗效。通过对pHi的调节,可纠正细胞内碱化,逆转肿瘤耐药。Na+-H+交换蛋白(Na+/H+exchanger,NHE)抑制剂可通过抑制NHE的活性调节pHi,为肿瘤的治疗提供了新的思路和手段。     

肺心病肺性脑病患者血清烯醇化酶与红细胞内Na+K+-ATP的变化

目的探讨血清烯醇化酶(NSE)及红细胞内Na+K+-ATP酶对肺心病肺性脑病的影响.方法选取36名肺心病肺性脑病患者(A组)抽取6ml静脉血检测NSE及Na+K+-ATP酶的活性与34例无肺性脑病患者(B组)及29例正常老年人比较(C组).结果发现A组的NSE活性较B组患者及C组增加(P＜0.05,且其活性与动脉血氧分压呈负相关(r=-0.514,P=0.018),与二氧化碳分压呈正相关(r=0.482,P=0.035),而红细胞内Na+K+-ATP酶较B组患者及C组下降(P＜0.05),且其活性与动脉血氧分压呈正相关(r=0.431,P=0.014),与二氧化碳分压呈负相关(r=-0.6344,P=0.0041).结论血清NSE活性与红细胞内Na+K+-ATP活性可以反映肺性脑病患者缺氧、CO2潴留引起的脑损害程度.     

熟地黄水提液对小鼠红细胞膜Na~+、K~+-ATPase活性及MDA含量的影响

本实验研究采用D-半乳糖衰老模型小鼠,灌胃熟地黄水提液30d,测定脑Na+、K+－ATPase活性和MDA含量．结果表明,与衰老模型组比较,熟地黄水提液能显著提高小鼠红细胞膜Na+、K+－ATPase活性,显著降低MDA含量（P<0．01）．     

红细胞膜Na~+-K~+-ATP酶活性红细胞膜流动性在新生儿缺氧缺血性脑病中的变化及其意义

目的了解新生儿缺氧缺血性脑病(HIE)中红细胞膜Na+-K+-ATP酶活性、红细胞膜流动性变化及其临床意义。方法选择新生儿科住院的中、重度HIE患儿65例,于急性期、恢复期采血测定红细胞膜Na+K+-ATP酶活性、红细胞膜流动性,并于同期行新生儿神经行为测定(NBNA)评分,对照组选择早期肺炎、咽下综合征、食管闭锁新生儿30例行相同测定,探讨HIE患儿红细胞膜Na+-K+-ATP酶活性、红细胞膜流动性、NBNA的相关关系。采用SPSS13.0统计软件进行统计学分析,组间比较采用单因素方差分析,相关性分析采用直线相关分析,以P<0.05为差异具有统计学意义。结果①中、重度HIE急性期患儿的红细胞膜Na+-K+-ATP酶活性、红细胞膜流动性均明显低于对照组(P<0.01),其中以重度组最低,亦显著低于同期中度组(P<0.05)。恢复期时中度组红细胞膜Na+-K+-ATP酶活性、红细胞膜流动性较同组急性期明显升高(P<0.01),且基本达到对照组水平(P>0.05);②HIE组急性期红细胞膜Na+-K+-ATP酶活性与NBNA评分呈正相关(r=0.507,P<0.05);HIE组恢复期红细胞膜Na+-K+-ATP酶活性与NBNA评分呈正相关(r=0.268,P<0.05);③HIE组急性期红细胞膜流动性与NBNA评分呈正相关(r=0.572,P<0.05);HIE组恢复期红细胞膜流动性与NBNA评分呈正相关(r=0.57,P<0.05)。结论临床检测红细胞膜Na+-K+-ATP酶活性、膜流动性有利于病情早期判断及预后估计。     

抗肝纤维化的新靶点:Na~+/H~+交换泵

Na+ /H+ 交换泵 (NHE)是调节细胞内pH和容积的重要膜蛋白。对启动细胞增殖、分化和凋亡起重要作用。NHE参与介导细胞因子和氧应激激活肝贮脂细胞和胶原的合成 ,因而与肝纤维化的形成密切相关。NHE有望成为重要的抗肝纤维化药物的靶点。     

Na~+/H~+交换泵1激活与心肌肥大

钠氢交换泵 1介导缺血及再灌流引起的心肌损伤。近期的研究提示钠氢交换泵 1也介导长期不良刺激引起的心肌肥大和心衰。钠氢交换泵 1可能是引起心肌肥大的多种因素信息传导下游区的共同媒介 ,比如血管紧张素Ⅱ ,肾上腺α1、β1受体兴奋等。抑制钠氢交换泵 1可能会成为防治心衰的一种新方法。     

The epithelial brush border Na+/H+ exchanger NHE3 associates with the actin cytoskeleton by binding to ezrin directly and via PDZ domain-containing Na+/H+ exchanger regulatory factor (NHERF) proteins

1. The Na(+)/H(+) exchanger NHE3 associates with the actin cytoskeleton by binding ezrin both directly and indirectly. Both types of interaction are necessary for acute regulation of NHE3. Most acute regulation of NHE3 occurs by changes in trafficking via effects on exocytosis and/or endocytosis. However, NHE3 activity can also be regulated without changing the surface expression of NHE3 (change in turnover number). 2. A positive amino acid cluster in the a-helical juxtamembrane region in the COOH-terminus of NHE3 (amino acids K516, R520 and R527) is necessary for binding to the protein 4.1, ezrin, radixin, moesin (FERM) domain III of ezrin. Direct binding of NHE3 to ezrin is necessary for many aspects of basal trafficking, including basal exocytosis, delivery from the synthetic pathway and movement of NHE3 in the brush border (BB), which probably contributes to endocytosis over a prolonged period of time. 3. In addition, NHE3 binds indirectly to ezrin. The PDZ domain-containing proteins Na(+)/H(+) exchanger regulatory factor (NHERF) 1 and NHERF2, as intermediates in linking NHE3 to ezrin, are necessary for many aspects of NHE3 regulation. The binding of NHERF-ezrin/radixin/moesin to NHE3 occurs in the cytosolic domain of NHE3 between amino acids 475 and 689. This NHERF binding is involved in the formation of the NHE3 complex and restricts NHE3 mobility in the BB. However, it is dynamic; for example, changing in some cases of signalling. Furthermore, NHERF binding is necessary for lysophosphatidic acid stimulation of NHE3 and inhibition of NHE3 by Ca(2+), cAMP and cGMP.     

Effects of volume depletion and NaHCO3 loading on the expression of Na+/H+ exchanger isoform 3, Na+: HCO3- cotransporter type 1 and nitric oxide synthase in rat kidney

1. The effects of volume depletion and NaHCO(3) loading on the expression of Na(+)/H(+) exchanger isoform 3 (NHE3), Na(+) : HCO(3)(-) cotransporter type 1 (NBC1) and neuronal (n) and inducible (i) isoforms of nitric oxide synthase (NOS) were determined in rat kidney. 2. Adult male Sprague-Dawley rats were used. Rats were divided into four groups: (i) euvolaemic (EC); (ii) hypovolaemic (HC); (iii) euvolaemia with NaHCO(3) loading (EB); and (iv) hypovolaemia with NaHCO(3) loading (HB). The expression of NHE3, NBC1, nNOS and iNOS proteins was determined in the cortex of the kidney by immunoblotting and immunohistochemistry. Tissue content of nitric oxide (NO) metabolites (NO(x)) were also determined in the cortex using a colourimetric assay. 3. Compared with the EC group, the expression of NHE3 and NBC1 was increased in the HC group and decreased in the EB group. Comparing the EB and HB groups, the expression of NHE3 and NBC1 was higher in the latter group. The expression of NHE3 was decreased and that of NBC1 was increased in the HB group compared with the HC group. The NO(x) content and nNOS expression were decreased in the hypovolaemic (HC) and NaHCO(3)-loaded (EB and HB) rats. Moreover, the expression of iNOS was decreased in the HB group compared with the other groups. 4. An altered volume status and NaHCO(3) loading may affect the regulation of NHE3 and NBC1 in the kidney and the endogenous NO system may play a role in the observed effects.     

Na+/H+ exchange inhibitors for ischemic diseases]

Cariporide, HOE642 (4-isopropyl-3-methylsulphonylbenzoyl-guanidine methanesulphonate), a novel Na(+)-H+ exchange (NHE) subtype 1 inhibitor, has cardioprotective effects including an antifibrillatory effect on the coronary ischemia/reperfusion induced arrhythmias not only in in vitro, but also in vivo animal hearts, which might be induced by intracellular Ca2+ overload following myocardial ischemia. This antifibrillatory effects on reperfusion arrhythmias were observed even when the drug was administered after induction of coronary ischemia or even when the drug was administered simultaneously with reperfusion. Other NHE inhibitors also have similar antiarrhythmic and antifibrillatory effects as cariporide and these drugs had almost no deleterious effects on the heart rate and blood pressure, nor ECG parameters. The antifibrillatory mechanism of NHE inhibitors may be due to their NHE inhibition as judged by the doses used, and they may become useful for treating or preventing arrhythmias in patients with coronary artery diseases.     

The myocardial Na+/H+ exchanger: a potential therapeutic target for the prevention of myocardial ischaemic and reperfusion injury and attenuation of postinfarction heart failure

The myocardial Na+/H+ exchange (NHE) represents a major mechanism for pH regulation during normal physiological processes but especially during ischaemia and early reperfusion. However, there is now very compelling evidence that its activation contributes to paradoxical induction of cell injury. The mechanism for this most probably reflects the fact that activation of the exchanger is closely coupled to Na+ influx and therefore to elevation in intracellular Ca2+ concentrations through the Na+/Ca2+ exchange. The NHE is exquisitely sensitive to intracellular acidosis; however, other factors can also exhibit stimulatory effects via phosphorylation-dependent processes. These generally represent various autocrine and paracrine as well as hormonal factors such as endothelin-1, angiotensin II and alpha1-adrenoceptor agonists, which probably act through receptor-signal transduction processes. Thus far, 6 NHE isoforms have been identified and designated as NHE1 through NHE6. All except NHE6, which is located intracellularly, are restricted to the sarcolemmal membrane. In the mammalian myocardium the NHE1 subtype is the predominant isoform, although NHE6 has also been identified in the heart. The predominance of NHE1 in the myocardium is of some importance since, as discussed in this review, pharmacological development of NHE inhibitors for cardiac therapeutics has concentrated specifically on those agents which are selective for NHE1. These agents, as well as the earlier nonspecific amiloride derivatives have now been extensively demonstrated to possess excellent cardioprotective properties, which appear to be superior to other strategies, including the extensively studied phenomenon of ischaemic preconditioning. Moreover, the salutary effects of NHE inhibitors have been demonstrated using a variety of experimental models as well as animal species suggesting that the role of the NHE in mediating injury is not species specific. The success of NHE inhibitors in experimental studies has led to clinical trials for the evaluation of these agents in high risk patients with coronary artery disease as well as in patients with acute myocardial infarction (MI). Recent evidence also suggests that NHE inhibition may be conducive to attenuating the remodelling process after MI, independently of infarct size reduction, and attenuation of subsequent postinfarction heart failure. As such, inhibitors of NHE offer substantial promise for clinical development for attenuation of both acute responses to myocardial as well as chronic postinfarction responses resulting in the evolution to heart failure.     

Blockade of Na+/H+ exchanger contracts the portal vein of spontaneously hypertensive and Wistar Kyoto rats

It has been claimed that the activity of Na+/H+ exchanger (NHE) is altered in spontaneously hypertensive rats (SHR) suggesting a possible role for it in the pathophysiology of hypertension. The purpose of this study has been to investigate the effect of blockade of NHE on the noradrenaline (NA) and 26K+ induced tone and on the recovery of tone from acid induced contractions in the portan vein of spontaneously hypertensive rats (SHR) as compared to their controls of Wistar Kyoto rats (WKY). Blockade of NHE by 10(-4) dimethylamiloride (DMA) raised the tone of NA and 26K+ activated preparation of both strains, the contractions being higher with NA activation. Total blockade of NHE by replacement of Na in solution with N-methy-D-Glucamine (NMDG) raised the tone of the NA activated preparations by 45+/-10%, n=8, P<0.01 and 33+/-4%, n=12, P < 0.01 in SHR and WKY respectively. The time for 50% relaxation from NH4Cl washout contraction was significantly prolonged by 10(-5) and 10(-4) M DMA in both strains under NA or 26K+ activation. DMA effect was greater on NA than on 26K+ activated preparations, and was not significantly different when comparing SHR to WKY results. In conclusion the results reported in this study indicate that NHE has similar activity in WKY and SHR portal veins and that its blockade contracts both preparations. Therefore, it is unlikely that increased NHE activity, acting directly on vascular smooth muscle tone, could be a primary cause for hypertension.