The CXCR4/CXCL12 axis in endometrial cancer

Chemokines and their receptors seem to act as important regulators of the metastatic cascade. CXCL12 and its receptor CXCR4 were shown to be involved in human cancer progression. There is increasing evidences suggesting that the expression of CXCR4 in human cancers is correlated with poor patient prognosis and that CXCR4 neutralization can prevent metastases in vivo. Here we tested the role of the CXCR4/CXCL12 axis in a neoplasia with a reduced risk of metastatic progression, such as human endometrial cancer. CXCR4 and CXCL12 mRNA expression was measured in 41 endometrial cancers and in corresponding not affected tissues. The expression of CXCR4 was predominant in endometrial cancer (P = 0.035) whereas CXCL12 was overexpressed in normal mucosae (P = 0.002). CXCR4 expression (P = 0.035), but not CXCL12, was significantly related to cancer differentiation. Endometrial cancer cells (HEC1A) were able to generate diffuse metastases in peritoneum, lung and liver of CD-1 nude mice, but the simultaneous treatment with a neutralizing anti-CXCR4 monoclonal antibody dramatically reduced the number and the size of metastases in the animals. In conclusion, our data seem to indicate that the CXCR4-CXCL12 axis can play a role in the progression of endometrial carcinoma and that specific therapies with antagonists of chemokines receptors could be of help in the treatment of metastatic patients.     

趋化因子基质细胞衍生因子1(SDF-1)及其受体CXCR4

趋化因子及其受体在免疫和炎症反应、造血以及HIV感染等方面发挥重要作用,其中基质细胞衍生因子-1SDF-1及其受体CXCR4由于在造血干细胞迁移、归巢以及HIV感染中的作用而受到关注,并对其作用机制进行了探讨,现就SDF-1及其受体CXCR4的有关内容作一综述。     

Grouper (Epinephelus coioides) CXCR4 is expressed in response to pathogens infection and early stage of development

Chemokine (C-X-C motif) receptor 4 (CXCR4) from orange-spotted grouper (Epinephelus coioides) was identified and characterized in this study. gCXCR4 shared common features in protein sequence and predicted structure of CXCR4 family. This suggested that gCXCR4 is a member of G protein-coupled receptors with seven transmembrane domains. The expression patterns revealed that gCXCR4 may play a key role in early development of grouper. Furthermore, overexpression of gCXCR4-GFP for 48 h had significant effects on the GF-1 cell viability. gCXCR4 protein was mainly expressed in the marginal zone of head kidney and on the surface of intestinal villi. gCXCR4 expression can be detected in all the examined tissues and significantly up-regulated in eye and brain, which are the main targets for nervous necrosis virus (NNV) infection and replication. gCXCR4 gene expression can be induced in the spleen and eye by lipopolysaccharide and NNV, respectively. Our data suggested that gCXCR4 may not only play a role in the early immune response to microbial infection but also restrain to the immune system and central nervous system.     

Subsets of human CD4(+) regulatory T cells express the peripheral homing receptor CXCR3

Regulatory T cells (Tregs) migrate into peripheral sites of inflammation such as allografts undergoing rejection, where they serve to suppress the immune response. In this study, we find that ～30–40% of human CD25^hi FOXP3⁺ CD4⁺ Tregs express the peripheral CXC chemokine receptor 3 (CXCR3) and that this subset has potent immunoregulatory properties. Consistently, we observed that proliferative responses as well as IFN‐γ production were significantly higher using CXCR3‐depleted versus undepleted responders in the mixed lymphocyte reaction, as well as following mitogen‐dependent activation of T cells. Using microfluidics, we also found that CXCR3 was functional on CXCR3^pos Tregs, in as much as chemotaxis and directional persistence towards interferon‐γ‐inducible protein of 10 kDa (IP‐10) was significantly greater for CXCR3^pos than CXCR3^neg Tregs. Following activation, CXCR3‐expressing CD4⁺ Tregs were maintained in vitro in cell culture in the presence of the mammalian target of rapamycin (mTOR) inhibitor rapamycin, and we detected higher numbers of circulating CXCR3⁺ FOXP3⁺ T cells in adult and pediatric recipients of renal transplants who were treated with mTOR‐inhibitor immunosuppressive therapy. Collectively, these results demonstrate that the peripheral homing receptor CXCR3 is expressed on subset(s) of circulating human Tregs and suggest a role for CXCR3 in their recruitment into peripheral sites of inflammation.     

Mutation Patterns in the Chemokine CXC Receptor 4 Gene Subfamily

Six representative CXCR4 mRNAs of fish, amphibia, birds, and mammals were selected to study the pattern of conservation/mutation of the individual nt of the coding sequences. According to an arbitrary conservation index ranging from 1 to 6, the indexes of conservation were: 5.04 for the first nt of coding triplets; 5.34 for the second nt of triplets, and 3.75 for the third nt of triplets. The average conservation index of the individual triplets was 4.71. The conservation index of the seven hydrophobic transmembrane domains was 5.60, while the cumulative conservation index of the intracytoplasmic and extracellular domains was 4.63. Separate autocorrelation and power spectral analyses of the series of conservation indexes for the first nt, the second nt and the triplets demonstrated a modest “basic” positive correlation for about the first 20 lags and accordingly some power concentration at the lower frequencies (long periods). Within the triplets, the correlation was studied between the conservation indexes of nt 1 and 2, 1 and 3, and 2 and 3. Correlations of 1 with 3 and 2 with 3 were positive, but in the range of the basic local correlation, whereas the correlation between the first and second nt was significantly higher. This correlation, together with the higher conservation of the second nt as compared to the first (two patterns also found in the formyl peptide receptors), are likely to have been established by selection processes directed towards a functional conservation or a “functional repair.”     

Differences in CXCR4-mediated signaling in B cells

Among all chemokine receptors CXCR4 possesses a unique response profile and distinguishes itself through a prolonged signaling capacity. Here, we investigated the signaling capacity of CXCR4 to its so far known unique ligand CXCL12 in B cell lines and primary CD19(+) B lymphocytes. During lymphopoiesis, CXCR4 is continuously expressed on the surface of B cells. However, its signaling profile changes inasmuch preB and proB cells migrate towards CXCL12, mobilize intracellular calcium and activate the small GTPases Rac1 and Cdc42, whereas mature B cells do not show these responses, albeit the cells retain the capability to migrate in response to CXCL13 and CCL21. By contrast, stimulation of B cells with CXCL12 at all stages of development results in the activation of the MAP-kinase cascade and in rapid CXCR4 internalization. The pathways leading to ERK1/2 activation are different in preB and mature B cell lines. In either case, ERK1/2 activation is pertussis toxin sensitive, but only in mature B-cells inhibition of PI3-kinase causes an almost complete block of ERK1/2 activation. Taken together, the results show that CXCR4 changes its coupling to downstream signal-transduction pathways in B cells, suggesting that receptor activity may depend on accessory proteins.     

趋化因子受体CXCR4在人肺癌高转移细胞株的表达和意义

目的：以人肺癌高、低转移细胞株95D、95C为研究对象，研究趋化因子受体CXCR4的表达及其在肿瘤细胞体外转移潜能中的作用和意义。方法：采用RT-PCR检测95D、95C细胞CXCR4 mRNA的表达情况；以PMA活化肿瘤细胞，研究CXCR4 mRNA表达水平与细胞活性状态的关系；应用钙离子内流实验验证其表达是否具有功能；通过趋化实验观察CXCR4特异性配件SDF-α和裸鼠组织匀浆液对95D细胞的趋化迁移作用；通过MTT法测定95D细胞对SDF-1α作用的增殖反应。结果：95D细胞功能性地高表达趋化因子受体CXCR4，且其表达水平与细胞活性状态有关；CXCR4特异性配件SDF-1α和裸鼠肺、淋巴结组织匀浆均可在体外趋化95D细胞的迁移，SDF-1α还可促进95D细胞的增殖。结论：95D细胞功能性高表达趋化因子受体CXCR4可能与人肺癌细胞株95D的体外高转移潜能有关。     

Activation of blood T lymphocytes down-regulates CXCR4 expression and interferes with propagation of X4 HIV strains

The chemokine receptor CXCR4 serves as a coreceptor for HIV-1 entry into CD4⁺ cells, in particular for strains emerging late in the infection. Cell surface expression of CXCR4 has, therefore, important implications for HIV-1 pathogenesis. Using blood lymphocytes cultured under various conditions, we studied the expression and regulation of CXCR4. Flow cytometry showed that only about 20 % of freshly isolated lymphocytes expressed CXCR4 on the cell surface whereas in 80 % of resting blood lymphocytes CXCR4 was located intracellularly. Within a few hours in culture, the intracellular CXCR4 was translocated to the surface and was expressed in the large majority of both naive and memory lymphocytes. A decrease in surface expression of CXCR4 was found when lymphocytes cultured overnight for maximal receptor expression were stimulated with phytohemagglutinin, anti-CD3 antibodies, phorbol 12-myristate 13-acetate and stromal cell-derived factor-1. The superantigen staphylococcal enterotoxin A, a more selective stimulus, induced a marked decrease in CXCR4 expression preferentially in cells positive for the CD25 activation marker. Confocal laser scanning microscopy demonstrated the presence of CXCR4 in the cytosol and on the surface of resting lymphocytes and also showed CXCR4 redistribution after activation. The number of cells infected by the X4 HIV strain NL4.3 paralleled the expression of CXCR4 in CD4⁺ T lymphocytes. Sustained reduction of CXCR4 cell surface expression upon activation with phytohemagglutinin correlated with a low number of CD4⁺ T lymphocytes expressing HIV p24 gag antigen. Our results indicate that activation of CD4⁺ T lymphocytes reduces surface expression of CXCR4 in part by receptor internalization and that cell activation-dependent CXCR4 down-regulation limits spread of infection by X4 viruses.     

An analysis of the human chemokine CXC receptor 4 gene

In this article we analyze some of the structural characteristics of the coding section and the intron of the human chemokine CXC receptor 4 (a 7-transmembrane receptor) pre-mRNA. In the coding sequence the frequencies of the individual nucleotides do not depart significantly from 0.25, while in the intron the frequencies of the As and Gs are significantly lower and higher, respectively, than expected from a random distribution. Analysis of the pattern of association of nucleotides into triplets or couples shows that some triplets or couples occur with frequencies significantly higher or lower than expected when assuming a random association of nucleotides. In particular, in the intron combinations of the same nucleotide are over-represented. 7-or-more nucleotide repeats occur in both the coding section and the intron with frequencies which exceed the confidence limits for a random distribution. For the coding sequence this is possibly explained by the alternans of relatively similar hydrophobic-coding sections and relatively similar intervening intracellular and extracellular hydrophilic-coding sections. 7-or-more nucleotide repeats in reverse order and in reverse/complemented order occur in the intron, but not in the coding section, with frequencies which significantly exceed a random distribution. The numerous intronic repeats in reverse/complemented order may be of relevance for the secondary structure of the intron and might be one important element of the integrated splicing code.     

Characterization and expression of the CXCR1 and CXCR4 in miiuy croaker and evolutionary analysis shows the strong positive selection pressures imposed in mammal CXCR1

The innate immune system can recognize non-self, danger signals, and pathogen associated molecular patterns and provides a first line of antimicrobial host defense. Therefore, it plays an instructive role and is pretty important in vertebrates. In innate immune responses, CXCRs act as the main receptors of CXC chemokines and play a vital role in host defense and inflammation. In present study, we cloned two cDNA molecules of CXCR1 and CXCR4 in Miichthys miiuy (miiuy croaker). In these two genes, we found the most highly conserved DRY motif in the second intracellular loop adjacent to the third transmembrane domain. The expressions of CXCR1 and CXCR4 showed that they were ubiquitously expressed in ten normal tissues. After infection with Vibrio anguillarum and Vibrio harveyi, the expressions of CXCRs in the immune tissues were significantly regulated in most of tissues except that of CXCR1 in the kidney after V. harveyi injection. Evolutionary analysis showed that only the ancestral lineages of CXCR4 in amphibians underwent positive selection, indicating that the ancestors of amphibians boarded the land and had to further evolve to adapt to terrestrial environments. Multiple ML methods were implemented to detect the robust positively selected candidates for sites. In total, we detected 12 and 3 positively selected sites in the subsets of current mammal and fish CXCR1 genes, and only one site under positive selection was found in mammalian CXCR4 subsets. These positively selected sites were mainly located in the extracellular domains of CXCRs. The sliding window analysis and evolution test tended to favor positive selection acting on the N-terminal domain of CXCR1, which was the critical region for ligand/receptor signaling for neutrophils and receptor–ligand interaction, indicating that the N-terminal of CXCR1 in mammals underwent more positive selection than that of fish.     

甲状腺癌组织中趋化因子4受体和趋化因子7受体的表达情况及临床病理意义

目的 研究甲状腺癌组织中趋化因子4受体(CXCR4)和趋化因子7受体(CXCR7)的表达情况及临床病理恿义.方法 选取2012年5月至2014年6月期间在本院进行外科手术的83例甲状腺癌患者及2014年45例甲状腺腺瘤患者,采用免疫组织化学染色方法检测甲状腺腺瘤及甲状腺癌中CXCR4和CXCR7的表达.结果 CXCR4和CXCR7在甲状腺癌中的表达阳性率均明显高于甲状腺腺瘤(P＜0.05).CXCR4和CXCR7在临床分期为Ⅲ～Ⅳ期的甲状腺癌患者中的表达阳性率均明显高于临床分期为Ⅰ～Ⅱ期者(P ＜0.05);CXCR7在有淋巴结转移的甲状腺癌患者中的表达阳性率明显高于无淋巴结转移者(P＜0.05),而CXCR4的表达阳性率与甲状腺癌患者有无淋巴结转移无关(P＞0.05);CXCR4和CXCR7在甲状腺癌组织中的表达阳性率与甲状腺癌患者性别无关(P＞0.05).在甲状腺癌患者中,CXCR4阳性表达和CXCR7阳性表达呈正相关(r =0.49,P＜0.01);在甲状腺腺瘤患者中,CXCR4阳性表达和CXCR7阳性表达不相关(r=0.14,P=0.21).结论 CXCR4和CXCR7参与了甲状腺癌的进展,并为临床上甲状腺癌诊断及靶向治疗提供理论基础.     

Involvement of the CXCL12/CXCR4 pathway in the advanced liver disease that is associated with hepatitis C virus or hepatitis B virus

Chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection is accompanied by inflammation and fibrosis eventually leading to cirrhosis. The chemokine CXCL12 is involved in chronic inflammatory conditions. The role of the CXCL12/CXCR4 pathway in HCV- and HBV-associated liver inflammation and fibrosis was therefore studied. The levels and tissue localization of CXCL12 in liver and plasma of HCV and HBV patients were tested using immunohistochemistry and ELISA. The expression and function of CXCR4 on liver-infiltrating lymphocytes (LIL) were tested by FACS and transwell migration assays. We found that CXCL12 is expressed by bile duct epithelial cells in normal liver tissue. Bile duct proliferation and liver fibrosis in chronic HCV and HBV infection result in the anatomical re-distribution of CXCL12 in the liver. Moreover, CXCL12 is up-regulated in the endothelium of neo-blood-vessels formed in active inflammatory foci and is significantly elevated, compared with controls, in the plasma of patients with advanced liver fibrosis. Complementing these observations were others indicating that over 50% of LIL express CXCR4 and, in response to CXCL12, migrated and adhered to fibronectin. These observations suggest an important role for the CXCL12/CXCR4 pathway in recruitment and retention of immune cells in the liver during chronic HCV and HBV infection.     

CXCL12-CXCR4/CXCR7轴信号传导通路与肿瘤细胞生物学特性的关系

越来越多的研究表明CXCR4与CXCR7在肿瘤的发生发展过程中发挥着重要作用,CXCR4与CXCR7作为G蛋白藕联受体介导的信号传导通路及其在胞内激化级联信号通路与肿瘤发生发展的分子机制有密切关系。本文将对它们各自介导的信号通路及其在胞内的级联信号通路与肿瘤细胞的生长、增殖、黏附和迁移等生物学特性的关系进行综述。     

生后大鼠海马CA区CXCR4蛋白的表达变化

目的:研究CXCR4蛋白在生后大鼠海马CA区的表达变化.方法:用免疫印迹法和免疫组织化学法定量、定位检测CXCR4在海马CA区的表达变化.结果:从生后4d到成年大鼠海马CA区均可见CXCR4蛋白表达阳性的细胞,其胞质呈棕黄色.生后早期,可见CA区锥体细胞伸出的轴丘上有棕黄色显色;后期其长轴突及短树突上也有不同程度CXCR4蛋白表达.免疫印迹检测显示,生后各时间点在分子量为43kD处均检测到CXCR4阳性条带.CXCR4在CA区的相对表达量于生后1周达高峰,随年龄增长逐渐下降,至生后3周CXCR4蛋白表达降至成年水平.结论:CXCR4蛋白在大鼠海马CA区的表达具有时空性差异,提示CXCR4参与了大鼠海马生后发育过程,并可能与不同时期海马结构和功能的发育有关.     

Chemokine receptor 4 (CXCR4) is part of the lipopolysaccharide "sensing apparatus"

Recognition of bacterial lipopolysaccharide (LPS) by the innate immune system involves at least three receptor molecules: CD14, TLR4 and MD-2. Additional receptor components such as heat shock proteins, chemokine receptor 4 (CXCR4), or CD55 have been suggested to be part of this activation cluster; possibly acting as additional LPS transfer molecules. Our group has previously identified CXCR4 as a component of the "LPS-sensing apparatus". In this study we aimed to elucidate the role that CXCR4 plays in innate immune responses to LPS. Here we demonstrate that CXCR4 transfection results in responsiveness to LPS. Fluorescence correlation spectroscopy experiments further showed that LPS directly interacts with CXCR4. Our data suggest that CXCR4 is not only involved in LPS binding but is also responsible for triggering signalling, especially mitogen-activated protein kinases in response to LPS. Finally, co-clustering of CXCR4 with other LPS receptors seems to be crucial for LPS signalling, thus suggesting that CXCR4 is a functional part of the multimeric LPS "sensing apparatus".     

基质细胞衍生因子-1及其受体CXCR4在肿瘤转移中的作用

基质细胞衍生因子-1(Stromal cell-derived factor-1,SDF-1)及其受体CXCR4与人类多种肿瘤转移密切相关,CXCR4在一些肿瘤细胞系、原发肿瘤组织均呈高表达。SDF-1在肿瘤细胞潜在转移靶器官的表达量比非常规转移靶器官高,肿瘤细胞利用CXCR4与其天然配体间的趋化效应实现远距离转移。SDF-1/CXCR4驱动癌细胞转移模式的提出及其相互作用机制的深入研究对于肿瘤治疗具有重要的指导意义。     

CXCR4-siRNA表达载体的构建及其对体外乳腺癌细胞侵袭能力的影响

目的 构建趋化因子受体（CXCR4）小分子干扰RNA ( siRNA) 表达载体,研究其对乳腺癌细胞侵袭能力的影响。方法 选择CXCR4高表达的乳腺癌MDA-MB-231细胞株,设计合成人CXCR4基因不同靶点的能编码siRNA的2条双链DNA序列,克隆到真核表达载体pGE-1-U6/kna中构建siRNA表达载体,体外脂质体介导转染MDA-MB-231细胞,用Western blot分析CXCR4蛋白表达,transwell 小室检测细胞的侵袭能力。结果 成功构建了CXCR4-siRNA表达载体,瞬时转染乳腺癌细胞后能显著降低CXCR4的蛋白表达,可有效抑制人类乳腺癌MDA-MB-231细胞的侵袭能力。结论 CXCR4- siRNA表达载体通过降低CXCR4基因的蛋白表达能显著抑制人类乳腺癌细胞的侵袭能力,有望为乳腺癌转移的基因治疗开辟新途径。     

CXCR4阳性Lewis肺癌细胞耐药实验研究

目的 研究CXCR4阳性Lewis肺癌细胞(Lewis lung carcinoma,LLC)原发性耐药机制.方法 激光共聚焦检测小鼠移植瘤组织内CXCR4阳性LLC;以CXCR4作为磁珠分选细胞的表面标志,应用CCK-8法检测CXCR4阳性和阴性LLC对顺铂的敏感性,RT-PCR检测两者ABCG2、IGF1R mRNA表达情况.结果 小鼠移植瘤组织内散在分布胞膜呈红色荧光的CXCR4阳性LLC;CXCR4阳性与阴性LLC比较,具有更强的增顺铂抗拒性(P<0.05);CXCR4阳性LLC的ABCG2 mRNA表达(0.5240±0.0078)明显高于CXCR4阴性LLC(0.3870±0.0066) ,相差显著(P<0.01);CXCR4阳性LLC的 IGF1R mRNA表达(0.4209 ±0.0074)明显高于CXCR4阴性LLC(0.1848±0.0066),相差显著(P<0.01).结论 Lewis肺癌细胞中的CXCR4阳性亚群具有更强上调ABCG2、IGF1R表达的能力,具有顺铂抗拒性.     

趋化因子及其受体CXCL12/CXCR4在人前列腺癌转移机制中的作用

目的 探讨趋化因子及其受体CXCL12/CXCR4在人前列腺癌转移机制中的作用.方法 免疫组织化学技术分析CXCL12/CXCR4蛋白在18例前列腺癌组织中的表达;免疫细胞化学技术分析CXCL12/CXCR4蛋白在人前列腺癌细胞株PC3、DU145和LNCap中的表达;迁移、侵袭试验分析外源性CXCL12对PC3、DU145和LNCap体外侵袭能力的调节作用.结果 18例人前列腺癌组织中,17例不同强度表达CXCR4蛋白,1例阴性表达,同时除1例标本弱表达CXCL12蛋白外,其余不表达CXCL12蛋白.3种前列腺癌细胞株均表达CXCR4蛋白,不表达CXCL12蛋白.外源性CXCLl2可明显促进PC3、DU145及LNCap的体外迁移、侵袭,以抗CXCL12或CXCR4抗体预处理PC3、LNCap细胞可以拮抗CXCL12对它们的促迁移、侵袭作用.结论 人前列腺癌组织表达CXCR4蛋白,CXCL12/CXCR4信号通路可能参与前列腺癌的侵袭、转移.