通过调节高迁移率族蛋白B1治疗相关疾病的药物研究进展

高迁移率族蛋白B1（high-mobility group box-1,HMGB1）是一种非组蛋白染色质结合蛋白,参与核小体结构的维持和基因转录调控。它可因受到多种因素刺激而释放到细胞外环境。胞外的HMGB1参与多种慢性炎症、自身免疫性疾病以及癌症的发展。目前已知HMGB1与细胞表面的糖化终末产物受体（receptor for advanced glycation end products, RAGE）的相互作用是这些疾病发展的一个重要信号通路,因此,抑制HMGB1与RAGE的相互作用及其调节通路可能是炎症调节以及肿瘤治疗的重要靶点。本文综述了在抑制HMGB1及其与之相关的炎症过程（尤其是HMGB1-RAGE信号通路）中的最新研究进展,以及通过调节HMGB1治疗相关疾病的药物的现状和应用前景。     

Interrelationship of apoptosis, mutation, and cell proliferation in N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced medaka carcinogenesis model

The present study examined the interrelationship of GSH depletion, apoptosis, mutation, and cell proliferation following carcinogen exposure. Medaka (Oryzias latipes) were investigated following a 28 day, three times/week pulse exposure to N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Fish (5 weeks old) were exposed to MNNG at concentrations of 0, 0.5, and 1 mg l⁻¹ and reared for 3, 5 and 7 more months after the last day of exposure. GSH levels were decreased in the higher concentration groups and longer-reared groups. Flow cytometric analysis revealed that fish from the groups reared 3 and 5 months showed active apoptotic changes in the dose- and time-dependent manner, but the group reared 7 months had fewer apoptotic, rather showed more necrotic and carcinogenic alterations. Mutational responses were detected by an arbitrarily primed polymerase chain reaction (AP-PCR) fingerprinting method using whole body DNA samples as templates and pBR primer. A mutational change was expressed by a loss or gain of a band. There was a time-dependent mutational change, but no distinctive concentration-dependent one. A band from normal fish sample that disappeared after treatment of MNNG was excised and sequenced. The band had an 869 base pair-long sequence, however, there was no putative protein-coding region based on an analysis by DNAsis. Spindle cell sarcomas invading muscle were detected on the whole body sections from three of ten fish examined, and immunohistochemical analysis with PCNA showed that tumor cells were actively proliferating. However, terminal deoxynucleotidyl transferase (TdT) assay showed that tumored fish still had active apoptotic cell changes in the tissues without tumor. This study shows not only the interrelationship of GSH depletion, apoptosis, mutation and cell proliferation, but also indicates that medaka is appropriate as a fish model for research on the passage of carcinogenesis.     

High mobility group box 1 protein, a cue for stem cell recruitment

High mobility group box 1 (HMGB1) is a non-histone protein required to maintain chromatin architecture. Recent observations demonstrated that HMGB1 can also act as a cytokine to regulate different biological processes such as inflammation, cell migration and metastasis. We showed previously that HMGB1 can be released passively by cells that die in a traumatic and unprogrammed way, and can serve a signal of tissue damage. More recently, we showed that HMGB1 can recruit stem cells: HMGB1 induces stem cell transmigration through an endothelial barrier; moreover, when beads containing HMGB1 are implanted into healthy muscle, they recruit stem cells injected into the general circulation. The inflammatory and tissue-regenerating roles of HMGB1 may be strictly interconnected, and are discussed here.     

Diethylnitrosamine exposure-responses for DNA ethylation, hepatocellular proliferation, and initiation of carcinogenesis in rat liver display non-linearities and thresholds

In previous exposure-response studies, we have documented non-linearities for some of the early effects in rat liver of diethylnitrosamine (DEN) and a near no-effect levels for initiation of promotable liver neoplasms at the lowest cumulative exposure of 0.5 mmol/kg body weight; this in spite of formation of DNA adducts and induction of hepatocellular altered foci (HAF). To extend these investigations, in an initiation segment, young male F344 rats were administered four exposures of DEN ranging from a cumulative total of 0.25 mmol, which is half of the previously used low exposure, up to 2 mmol per kg body weight, an effective initiating exposure. These exposures were achieved by once weekly intragastric instillations of one-tenth the total exposures for up to 10 weeks. The initiation segment was followed by a 4 week recovery segment, to allow for remission of acute and subchronic effects of DEN, after which the groups were maintained on 0.06% phenobarbital in the diet for 24 weeks to promote liver tumor development in order to assess initiation. During and after initiation and at the end of recovery, selected groups were studied for several crucial effects involved in hepatocarcinogenicity. The low exposure produced a low-level of DNA ethylation at both 5 and 10 weeks of exposure, measured as O⁴-ethylthymidine, the most persistent promutagenic ethylation product. At the 5 week interval, the adduct values of the higher exposures were less than proportional to the increment of exposure, suggestive of nonlinearity. Assessment of cellular proliferation by staining for proliferating cell nuclear antigen revealed that the lowest exposure did not increase the replicating fraction of hepatocytes during the initiation (10 weeks) or recovery (4 weeks) segments, whereas in the three higher exposure groups, proliferation was increased in relation to dose and time. Preneoplastic HAF expressing glutathione S-transferase-placental-type were present at low multiplicity in control livers and their multiplicity was increased in all exposure groups by the end of exposure, at which time the increase in the high exposure group was disproportionately greater than the increment of exposure. After phenobarbital administration in the promotion segment, all exposure groups exhibited further HAF increases at 39 weeks. At the end of the promotion segment, no hepatocellular neoplasm was found in 80 controls or in 40 rats in the low exposure group. In the mid-low exposure group, which was the previously studied low exposure, only one adenoma was found, yielding a 3% incidence, while in the two higher exposure groups, 32 and 80% of rats exhibited liver neoplasms, which were increased disproportionately greater than the increments of exposure. Thus, the findings document non-linearities of early DEN effects and at the lowest cumulative dose, a no-effect level (NEL) or threshold for initiation of promotable liver neoplasms. These findings provide a conceptual basis for understanding why low-level exposures to DNA-reactive carcinogens may convey no cancer risk. Received: 23 February 1999 / Accepted: 8 June 1999     

寻常性银屑病患者血清高迁移率蛋白和血管内皮细胞钙黏蛋白的含量变化

目的 探讨血清高迁移率蛋白1( HMGB1)和血管内皮细胞钙黏蛋白(VE-cadherin)含量变化在寻常性银屑病发病中的作用及其临床意义.方法 应用双抗体夹心酶联免疫吸附法( ELISA)检测78例寻常性银屑病患者外周血清中HMGB1和VE-cadherin的水平;并动态观察治疗前后HMGB1和VE-cadherin的变化及其与寻常性银屑病患者病情活动指标之间的关系.结果 寻常性银屑病患者血清中HMGB1和VE-cadherin的水平[分别为(2.58 ±0.19)、(4.22±0.81) mg/L]较正常对照组[分别为(0.86±0.12)、(2 87±0.64)mg/L]明显增高(t=10.53,10.16,P＜0.01).进行期与静止期的寻常性银屑病患者血清中HMGB1和VE-cadherin水平[进行期患者分别为(3.58±0.17)、(5.62±0.85) mg/L,静止期分别为(2.07±0.12)、(3.45±0.82) mg/L]差异有统计学意义(t=12.47,13.11,P＜0.01).治疗中、治疗后血清HMGB1、VE-cadherin水平及银屑病面积与严重性指数(PASI)评分与治疗前相比明显下降[治疗前分别为(2.58±0.19)、(4.22±0.81) mg/L,(12.0±4.2)分;治疗中分别为(1.98±0.17)、(3.45±0.79) mg/L,(8.38±3.49)分;治疗后分别为(0.92±0.19)、(2.94±0.65) mg/L,(2.67±0.87)分],差异有统计学意义(治疗中与治疗前相比,t=7.48、7.92、6.67,P＜0.05;治疗后与治疗前相比,t=12.72,11.48,13.13,P＜0.01).治疗后与对照组相比,HMGB1和VE-cadherin的水平差异无统计学意义.寻常性银屑病患者治疗前后血清HMGB1和VE-cadherin水平及银屑病PASI评分呈明显正相关(r=0.58,0.64,P＜0.01);同时VE-cadherin水平与银屑病PASI评分呈明显正相关(r=0.53,P＜0.01).结论 HMGB1和VE-cadherin在寻常性银屑病的发病中可能起重要作用,血清HMGB1和VE-cadherin的检测可作为反映寻常性银屑病病情活动的指标之一.     

HMGB1和MMP-9在食管鳞癌组织中的表达及临床意义

目的 探讨高迁移率族蛋白B1(HMGB1)和基质金属蛋白酶-9(MMP-9)在食管鳞癌组织中的表达及临床意义.方法 采用免疫组化EnVision法检测食管鳞癌组织(A组,87例)和癌旁正常黏膜组织(B组,40例)中HMGB1和MMP-9的表达.结果 A组HMGB1和MMP-9阳性表达率均高于B组(69.0％ vs.22.5％和62.1％ vs.12.5％)(P＜0.05).A组HMGB1和MMP-9阳性表达与肿瘤浸润深度、TNM分期有关(P＜0.05).A组HMGB1和MMP-9表达呈正相关(rs =0.295,P＜0.01).结论 联合检测食管鳞癌组织中HMGB1和MMP-9蛋白表达可能有助于评估食管鳞癌的恶性程度.     

The tumor-promoting activity of 2-acetylaminofluorene is associated with disruption of the p53 signaling pathway and the balance between apoptosis and cell proliferation

The aromatic amine 2-acetylaminofluore (2-AAF) is a powerful complete genotoxic rat liver carcinogen that induces tumors without any additional interventions. While the tumor-initiating genotoxic activity of 2-AAF is well established, its tumor-promotion activity is far less understood. It is believed that the tumor-promoting property of 2-AAF is associated with selective enhancement of cell replication and sustained suppression of apoptosis in initiated cells. In the present study, we investigated the underlying mechanisms of tumor-promoting events induced by 2-AAF-exposure. Male Sprague-Dawley rats were fed NIH-31 diet containing 0.02% of 2-AAF for 12 and 24 weeks, and the expression pattern of genes associated with the p53-signaling pathway and microRNA genes was determined in the livers of control and 2-AAF-fed rats. The results indicate that the tumor-promoting property of 2-AAF during hepatocarcinogenesis is associated predominantly with the up-regulation of anti-apoptotic growth-related genes and down-regulation of expression of pro-apoptotic genes. This disrupts the balance between cell proliferation and apoptosis, which leads to consequential unrestricted cell proliferation, especially of initiated cells. Also, the long-term-administration of 2-AAF resulted in disruption of regulatory miR-34a-p53 feed-back loop that mediates apoptosis. This was evidenced by an increased expression of miR-34a in response to genotoxic effects of 2-AAF in the absence of p53 up-regulation, and loss of regulatory control of mir-34a on SIRT1 function. Additionally, the livers of 2-AAF-exposed rats were characterized by the substantial deregulation of expression of miR-18, miR-21, miR-182, and miR-200 family, microRNAs involved in control of apoptosis/cell proliferation and cell-cell contact pathways, two major pathways disrupted during the promotion stage of hepatocarcinogenesis.     

微小RNA-21对肝癌患者的HepG2细胞增殖的调控作用

目的研究微小RNA-21(miR-21)在肝癌HepG2细胞中对增殖的作用并探讨相关的机制。方法收集2012年至2015年本院收治的98例肝癌患者,分离其肝癌组织和癌旁组织,用免疫组化法检测丝裂原激活蛋白激酶激酶3(MAP2K3)的表达情况;肝癌细胞系HepG分为mimic-miR-21组与miR-21抑制药组,分别转染mimic-miR-21与miR-21抑制药。转染48 h后,以3-(4,5-二甲基噻唑-2-基)-5-(3-羧甲酯基)-2-(4-磺苯基)-2H-四唑法检测在24,48,72 h的HepG2细胞的增殖情况,用实时定量聚合酶链式反应(qPCR)法检测HepG2细胞中miR-21和MAP2K3 mRNA的表达水平,以免疫印迹法检测MAP2K3的表达水平。结果 MAP2K3在肝癌组织与癌旁组织中的表达强度分别为1382±105,5872±289;HepG2细胞转入mimicmiR-21与miR-21抑制药24 h后,mimic-miR-21组与miR-21抑制药组的miR-21 mRNA表达量分别为6.45±1.21,0.43±0.12。mimic-miR-21与miR-21抑制药组的增殖活性在24,48,72 h分别是(100±12)%,(60±18)%;(138±12)%,(45±8)%;(146±9)%,(38±6)%,以上指标组间差异均有统计学意义(均P<0.05)。HepG2细胞转入mimic-miR-21与miR-21抑制药24h后,mimic-miR-21组与miR-21抑制药组的MAP2K3在RNA表达水平分别为0.17±0.03,0.97±0.09,组间比较差异均有统计学意义(均P<0.05)。结论 miR-21可通过抑制MAP2K3的表达从而促进肝癌HepG2细胞增殖。     

Oxidative DNA damage and cell proliferation in kidneys of male and female rats during 13-weeks exposure to potassium bromate (KBrO3)

It has been assumed that oxidative damage, including formation of 8-hydroxydeoxyguanosine (8-OHdG) adducts in kidney DNA due to potassium bromate (KBrO₃), a renal carcinogen to both sexes of rats, is involved in its mechanisms of tumor induction. However, despite the presumed existence of a repair enzyme(s) for 8-OHdG, there have been no reports demonstrating the changes in adduct levels during medium- or long-term exposure. To elucidate the actual kinetics regarding this parameter during the early stages of KBrO₃ carcinogenesis, we measured 8-OHdG levels in kidney DNA together with cell proliferation in renal tubules in both sexes of rats receiving KBrO₃ at a dose of 500 ppm in the drinking water for 1, 2, 3, 4, and 13 weeks. Rapid elevation of 8-OHdG levels was noted in treated male rats which persisted until the end of the experiment. Increased cell proliferation in the proximal convoluted tubules was also observed throughout the experimental period, concomitant with ₂-globulin accumulation. Increase in 8-OHdG levels in treated females first became apparent 3 weeks after the start of exposure, with cell proliferation only elevated at the 13-week time point. The present study, employing the same route and dose of KBrO₃ known to cause tumors, strongly suggested the requirement of persistent increase of 8-OHdG for neoplastic conversion. Moreover, a clear sex difference in susceptibility to generation of oxidative stress in kidney DNA was found, in addition to ₂-globulin-dependent variation in cell proliferation in the renal tubules. Received: 10 September 1997 / Accepted: 17 November 1997     

Dexmedetomidine preconditioning for myocardial protection in ischaemia‐reperfusion injury in rats by downregulation of the high mobility group box 1‐toll‐like receptor 4‐nuclear factor κB signalling pathway

Pharmacological preconditioning reduces myocardial infarct size in ischaemia‐reperfusion (I‐R) injury. Dexmedetomidine, a selective α₂‐adrenoceptor agonist, has a proven cardioprotective effect when administered prior to I‐R, although the underlying mechanisms for this effect are not fully understood. We evaluated whether dexmedetomidine preconditioning could induce a myocardio‐protective effect against I‐R injury by inhibiting associated inflammatory processes through downregulation of the high mobility group box 1 (HMGB1)‐toll‐like receptor 4 (TLR4)‐nuclear factor κB (NF‐κB) signalling pathway. Seventy rats were randomly assigned to seven groups: a control and six test groups, involving I‐R for 30 and 120 minutes, respectively, in isolated rat hearts and different pretreatment protocols with dexmedetomidine (10 nmol/L) as well as yohimbine (1 μmol/L) and recombinant HMGB1 peptide (rHMGB1; 20 μg/L), alone or in combination with dexmedetomidine. Cardiac function was recorded; myocardial HMGB1, TLR4, and NF‐κB activities and levels of tumour necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) were measured as were lactate dehydrogenase (LDH) and creatine kinase (CK) in coronary outflow. Dexmedetomidine preconditioning significantly improved cardiac function (P<.05), downregulated the expression of HMGB1‐TLR4‐NF‐κB, reduced levels of TNF‐α and IL‐6 in isolated ventricles during I‐R injury, and significantly reduced CK and LDH levels in coronary outflow (P<.05). All of these effects were partially reversed by yohimbine (P<.05) or rHMGB1 (P<.05). Dexmedetomidine preconditioning alleviated myocardial I‐R injury in rats through inhibition of inflammatory processes associated with downregulation of the HMGB1‐TLR4‐NF‐κB signalling pathway via activation at α₂‐adrenergic receptors.