CXCL12(SDF-1)-CXCR4及CXCL12-CXCR7与胃癌相关性研究进展

胃癌是最常见的恶性肿瘤之一,远处转移是其预后不良的主要原因.既往研究认为CX-CR4是趋化因子CXCL12的唯一受体,CXCL12/CXCR4轴在胃癌的发生发展过程中起着重要作用,然而最近研究表明CXCL12尚存在CXCR7这一新的受体,并且CXCL12/CXCR7轴同样对肿瘤的发生发展起重要作用.     

CXCL12／CXCR4对胰腺癌细胞生物学行为的影响

目的探讨CXCLl2／CXCR4生物轴对胰腺癌细胞增殖、侵袭等生物学行为的影响。方法体外培养胰腺癌细胞系Miapaca-2,将其分为对照组、CXCLl2组和AMD3100组。（1）采用RT—PCR检测胰腺癌细胞中CXCLl2、CXCR4、基质金属蛋白酶-2（MMP-2）、基质金属蛋白酶-9（MMP-9）和人尿激酶型纤溶酶原激活物（uPA）mRNA的表达水平;（2）采用CCK-8法检测各组细胞的增殖情况;（3）采用Transwell侵袭实验检测CXCLl2／CXCR4对胰腺癌细胞趋化活性的影响。结果胰腺癌细胞系Miapaca-2中CXCLl2mRNA未见表达,而CXCR4mRNA在胰腺癌细胞中有表达。MMP-2、MMPO和uPAmRNA在AMD3100组、对照组和CXCLl2组中的表达水平呈递增趋势,差异具有统计学意义（P〈0．05）。胰腺癌细胞的增殖和侵袭能力在CXCLl2组明显增强,而在AMD3100组得到了有效的抑制,组间差异有统计学意义（P〈0．05）。结论趋化因子CXCLl2及其受体CXCR4所构成的生物轴对胰腺癌细胞的增殖和侵袭能力发挥着重要的作用。     

The expression of CXCR4, CXCL12 and CXCR7 in malignant pleural mesothelioma

The chemokine CXCL12 and its receptors, CXCR4 and CXCR7, are involved in tumour progression, metastasis, and survival. We investigated the expression of CXCR4, CXCL12, and CXCR7 in malignant pleural mesothelioma to determine if they are possible biomarkers and potential therapeutic targets. Forty-one mesothelioma tumour tissues, ten normal human pleural tissues, and two mesothelioma cell lines were stained with anti-CXCR4, anti-CXCL12, anti-CXCR7, and anti-p-Akt antibodies. RT-PCR was performed to determine the expression of CXCR4, CXCL12, and CXCR7 in six human mesothelioma cell lines (H28, 211H, H2052, ms-1, H290, and H513) and one human normal mesothelial cell line, LP9. These seven cell lines were also stained with anti-CXCR7. We found that CXCR4 and CXCL12 were expressed in 97.6% and 78.0% mesothelioma tissue samples, concurrently with strong expression of p-Akt (R(2) = 0.739 and 0.620, respectively). In addition, CXCR7 expression was weaker than CXCR4 expression in mesothelioma tissues. Furthermore, RT-PCR showed that CXCR4 and CXCL12 were overexpressed in 5/6 mesothelioma cell lines (211H, H2052, ms-1, H290, and H513), whereas CXCR7 was overexpressed in only 2/6 (H513 and H2052). Moreover, we found that the CXCR4 antagonist AMD3100 inhibited the growth of all five mesothelioma cell lines that overexpress CXCR4 and CXCL12. Our results suggest that the Akt-mTOR pathway is involved during the interruption of the CXCL12/CXCR4 axis in these five mesothelioma cell lines. In conclusion, CXCR4 and CXCL12 are highly expressed in most mesothelioma cell lines and tumour tissues, suggesting that CXCR4 and CXCL12 may be used as biomarkers for patients with mesothelioma. The CXCL12-CXCR4 interaction may be a potential therapeutic target for mesothelioma.     

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.     

Role of the CXCL12/CXCR4 axis in milky spots of rats bearing ascitic-type hepatoma

Rat ascitic-type hepatoma AH7974 cells express CXCR4 mRNA and protein at high levels and also show vigorous migratory responses to its ligand CXCL12. We have shown that AMD3100 (a specific CXCR4 antagonist) effectively reduced tumor invasion into the milky spot in Sprague–Dawley rats inoculated with AH7974 cells. A histological analysis revealed that the milky spots from AMD3100-treated rats were both smaller and consisted of fewer constituent cells and blood vessels than those from the AH7974 inoculated rats. Alkaline phosphatase staining also showed a statistically significant reduction in the area of the milky spots in the AMD3100-treated rats in comparison to the AH7974 inoculated rats (P < 0.0001). Green fluorescence protein (GFP)-tagged AH7974 cells were constructed to detect the localization of the tumor cells in the milky spots. There were fewer GFP-tagged AH7974 cells in the AMD3100-treated rats than in the AH7974 inoculated rats. The number of eosinophils and mast cells increased in the milky spots of AH7974-inoculated rats, and angiogenesis was also seen. In comparison, both cell proliferation and angiogenesis were inhibited in the milky spots of the AMD3100-treated rats. Collectively, our results strongly suggest that the CXCR4/CXCL12 axis plays an important role in the development of peritoneal carcinomatosis. As such, CXCR4 may be a potential therapeutic target for peritoneal carcinomatosis.     

Endothelial expression of CXCR7 and the regulation of systemic CXCL12 levels

The concentration of CXCL12/SDF‐1 in the bloodstream is tightly regulated, given its central role in leucocyte and stem/progenitor cell egress from bone marrow and recruitment to sites of inflammation or injury. The mechanism responsible for this regulation is unknown. Here we show that both genetic deletion and pharmacological inhibition of CXCR7, a high‐affinity CXCL12 receptor, caused pronounced increases in plasma CXCL12 levels. The rise in plasma CXCL12 levels was associated with an impairment in the ability of leucocytes to migrate to a local source of CXCL12. Using a set of complementary and highly sensitive techniques, we found that CXCR7 protein is expressed at low levels in multiple organs in both humans and mice. In humans, CXCR7 was detected primarily on venule endothelium and arteriole smooth muscle cells. CXCR7 expression on venule endothelium was also documented in immunodeficient mice and CXCR7^+/lacZ mice. The vascular expression of CXCR7 therefore gives it immediate access to circulating CXCL12. These studies suggest that endothelial CXCR7 regulates circulating CXCL12 levels and that CXCR7 inhibitors might be used to block CXCL12‐mediated cell migration for therapeutic purposes.     

胃癌组织中CXCL12和CXCR4的表达及意义

目的观察趋化因子CXCL12及其特异性受体CXCR4在人胃癌组织中的表达,探讨其与临床病理参数、预后的关系。方法选择120例胃癌标本,应用免疫组化SP法检测CXCL12和CXCR4在人胃癌组织中的表达,分析CXCL12和CXCR4的表达与患者临床病理参数、术后生存率之间的关系。结果胃癌组织及正常胃黏膜组织中均可检测到CXCL12、CXCR4的表达,但胃癌组织中的表达水平均明显高于正常胃黏膜组织,表达差异有显著性(P<0.05)。CXCL12阳性与CXCR4阳性呈正相关(r=0.276,P<0.05)。胃癌CXCL12和CXCR4的表达水平与肿瘤细胞淋巴结转移及分化程度密切相关(P<0.05),与患者的年龄、性别、肿瘤的大小、浸润深度及远处转移等无关(P>0.05)。CXCL12和CXCR4阳性表达的患者其五年生存率明显低于其阴性表达的患者。结论胃癌中CXCL12和CXCR4的高表达与胃癌的生物学行为及预后密切相关,检测其表达对预测胃癌的转移及判断预后有一定价值。     

LPS-induced migration of peritoneal B-1 cells is associated with upregulation of CXCR4 and increased migratory sensitivity to CXCL12

B-1 cells, which constitute a predominant lymphocyte subset in serosal cavities and produce most of natural antibodies, are subdivided into the CD5(+) B-1a and CD5(-) B-1b cell subpopulations, but the differential roles of B-1a and B-1b cells are not well understood. We report that B-1a cells preferentially migrate out of the peritoneal cavity and upregulate the expression of CXCR4 with heightened sensitivity to CXCL12 and CXCL13 upon LPS treatment compared to B-1b and B-2 cells. Whereas B-1a cells were slightly more abundant than B-1b and B-2 cells in the homeostatic condition, the number of B-1a cells preferentially decreased 48 hr after LPS treatment. The decrease in the peritoneal B-1a cell number was accompanied with increased migration of B-1a cells toward CXCL-12 and CXCL-13 in in vitro transmigration assay using peritoneal B cells from LPS treated mice. The expression level of CXCR4, but not of CXCR5, was also more prominently increased in B-1a cells upon LPS stimulation. LPS-stimulated B-1a cells did not accumulate in omental milky spots in contrast to B-2 cells. These results suggest that B-1a cells actively migrate out of the peritoneal cavity through the regulation of the migratory responsiveness to chemokines and actively participate in systemic immune responses.     

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。     

The CXCL12/CXCR4 axis is involved in the maintenance of Th2 bias at the maternal/fetal interface in early human pregnancy

The regulatory mechanism of Th2 bias at the maternal/fetal interface remains unclear. In this study, we characterized cytokine production in decidual stromal cells (DSCs), decidual immune cells (DICs) and embryo-derived trophoblast cells, and investigated the regulation of CXCL12/CXCR4 interaction on Th2 bias at the maternal/fetal interface in early human pregnancy. We found differential production of Th1-type and Th2-type cytokines by trophoblasts, DSCs and DICs. The secretion of these cytokines varied in different cell cocultures, conduced to Th2 bias. Flow cytometry showed that coculture of trophoblasts with DSCs and DICs significantly increased IL-4 and IL-10 production in trophoblasts, and IL-10 production in DSCs. However, the coculture of trophoblasts with DSCs and DICs significantly increased interferon (IFN)-γ expression in DSCs, and tumor-necrosis factor (TNF)-α expression in DICs. No change was seen in Th1-type cytokine production in trophoblasts, and in Th2-type cytokine production in DICs in all cocultures. Furthermore, pre-treatment with anti-CXCR4 neutralizing antibody upregulated the production of the Th1-type cytokines IFN-γ and TNF-α, and downregulated the production of the Th2-type cytokines IL-4 and IL-10, in trophoblasts, DSCs, DICs or their cocultures. Interestingly, rhCXCL12 inhibited production of the Th1-type cytokine TNF-α and enhanced the expression of the Th2-type cytokines such as IL-4 and IL-10 in DICs; this effect was abrogated by anti-CXCR4 antibody. Our present study has elucidated the individual contributions of component cells to the shaping of Th2 bias, and uncovered a complicated cross-talk via the CXCL12/CXCR4 signal at the maternal/fetal interface in early human pregnancy.     

CXCL12 and CXCR4 expression by human gingival fibroblasts in periodontal disease

CXCL12 is a CXC chemokine that is related to lymphocyte infiltration and angiogenesis in inflammatory sites such as arthritis. However, the expression and roles of CXCL12 in periodontal disease are uncertain. The aim of this study was to assess the expression of CXCL12 and its receptor, CXCR4, in periodontal tissue and to investigate the properties of CXCL12 and CXCR4 expression by human gingival fibroblasts (HGF). RT-PCR analysis revealed that CXCL12 and CXCR4 mRNA were expressed in both normal gingival tissues and periodontal diseased tissues. Immunohistochemistry disclosed that CXCL12 was expressed and CXCR4 positive cells were found in both normal and periodontal diseased gingival tissues. Our in vitro experiments elucidated that HGF constitutively produced CXCL12, and the levels were enhanced by stimulation with tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein 3(alpha) (MIP-3(alpha)). On the other hand, heat killed Porphyromonas gingivalis (P. gingivalis) and P. gingivalis LPS reduced the CXCL12 production by HGF. Flow cytometry analysis clarified that CXCR4 was highly expressed on HGF, and CXCR4 expression was abrogated by TNF-alpha, IFN-gamma and P. gingivalis LPS. Moreover, CXCL12 induced vascular endothelial growth factor (VEGF) production by HGF. Our results demonstrated that CXCL12 might be related to CXCR4+ cells infiltration and angiogenesis both in normal periodontal tissues and periodontal diseased tissue. P. gingivalis, a known periodontal pathogen, inhibits the production of CXCL12 and the expression of CXCR4 by HGF. This fact means that P. gingivalis may inhibit CXCR4+ cells infiltration and neovascularization in periodontal tissue and escape from the immune response.     

CXCL12、CXCR4、MMP-2在宫颈鳞癌组织的表达及意义

目的探讨趋化因子CXCL12与其受体CXCR4及金属蛋白酶MMP-2在宫颈鳞癌组织中的表达及临床意义。方法采用免疫组织化学SP法检测50例宫颈鳞癌组织及50例癌旁正常组织中CXCL12、CXCR4、MMP-2的表达。结果 CXCL12、CXCR4、MMP-2在宫颈鳞癌组织中的阳性表达率(68.0%、72.0%、78.0%)明显高于正常宫颈组织(12.0%、24.0%、30.0%),在中/低度分化的宫颈鳞癌组织阳性表达率分别为84.4%、75.0%、87.5%。CXCL12、CXCR4、MMP-2在宫颈鳞癌淋巴结转移组中阳性表达率(86.2%、82.8%、79.3%)也明显高于无淋巴结转移组(52.4%、57.1%、52.4%)。在宫颈鳞癌组织中CXCL12与CXCR4、MMP-2表达都呈正相关(r=0.355,P=0.004;r=0.310,P=0.036);MMP-2与CXCR4表达也呈正相关(r=0.297,P=0.042)。结论 CXCL12和受体CXCR4、MMP-2与宫颈鳞癌的病变进展和转移密切相关,可能对宫颈鳞癌的预后和复发具有指导意义。     

Roles of Chemokine Receptor 4 （CXCR4） and Chemokine Ligand 12 （CXCL12） in Metastasis of Hepatocellular Carcinoma Cells

Chemokines are involved in human hepatocellular carcinoma （HCC） carcinogenesis. However, the exact mechanism of chemokines in HCC carcinogenesis remains unknown. Here we investigated the roles of chemokine receptor 4 （CXCR4） and chemokine ligand 12 （CXCL12） in the metastasis of HCC. We found that the expression levels of CXCR4 mRNA in HCC tissues, MHCC97 cells, and HUVEC cells were 2.52 ±1.13, 2.34 ±1.16 and 1.63 ±1.26, respectively and that the CXCR4 protein levels were 1.38 ± 0.13, 1.96± 0.32 and 1.86 ±0.21, respectively. In contrast, CXCR4 was not detected in normal hepatic tissues. In 78 HCC patients, we also found that the concentration of CXCL12 in cancerous ascitic fluid was 783-8,364 pg/ml and that CXCL12 mRNA level in HCC metastasis portal lymph nodes was 1.21 ± 0.87 but undetectable in normal hepatic tissues. Finally we discovered that recombinant human CXCL12 could induce MHCC97 cells and HUVEC cells to migrate with chemotactic indexes （CI） of 3.9 ±1.1 and 4.1± 1.6, respectively. Cancerous ascitic fluid could also induce the migration of MHCC97 cells with a CI of 1.9 ± 0.8. Thus, our data suggest that CXCR4 and CXCL12 may play an important role in the metastasis of HCC by promoting the migration of tumor cells.     

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.     

CXCL12 in normal and pathological pregnancies: A review

The survival of allogeneic fetuses during pregnancy is a rather paradoxical phenomenon with a complex mechanism. Chemokine ligand12 (CXCL12) and its receptors CXC chemokine receptor (CXCR)4 and 7 are extensively found in placenta tissues and cells, including trophoblast cells, vascular endothelial cells, and decidual stromal and decidual immune cells (eg, NK cells and regulatory T cells). Evidence has illustrated that the CXClL12/CXCR4/CXCR7 axis could enhance the cross talk at the maternal‐fetal interface through multiple processes, such as invasion and placental angiogenesis, which appears to be critical signaling components in placentation and fetal outcome. In addition, an increasing number of studies have demonstrated that the CXCL12/CXCR4/CXCR7 axis also stands out for its pleiotropic roles in several pregnancy‐associated diseases (eg, recurrent spontaneous abortion (RSA), pre‐eclampsia (PE), and preterm labor). In the present review, the different biological properties and signaling in physiological and pathological pregnancy conditions of CXCL12/CXCR4/CXCR7 axis were discussed, with the aim of obtaining a further understanding of the regulatory mechanisms and highlighting their potential as a target for therapeutic approaches.     

CXCL12-induced partitioning of flotillin-1 with lipid rafts plays a role in CXCR4 function

Lipid rafts play an important role in signal integration and in the cellular activation of a number of cytokine and growth factor receptors. It has recently been demonstrated that flotillin proteins are recruited to lipid raft microdomains upon cellular activation and play a role in neural cell regeneration, receptor signaling and lymphocyte activation. However, little is known about the relevance of the flotillin proteins during T cell responses to chemoattractant stimulation. To this end, cytoplasmic and lipid raft fractions from human T cells were analyzed for flotillin protein redistribution prior to and after CXCL12 stimulation. Flotillin-1, but not flotillin-2, redistributes to lipid rafts upon CXCR4 ligation. Moreover, in CXCL12-treated T cells, flotillin-1 also associates with several raft proteins including LAT, CD48 and CD11a but not Lck. In addition, an increase in CXCR4 association with flotillin-1 in lipid rafts was observed after chemokine treatment. RNAi technology was also utilized to inhibit the expression of flotillin-1, resulting in an inhibition of CXCL12-mediated signaling, function and CXCR4 recruitment into lipid rafts. Together, these data suggest that the increased association of cellular flotillin-1 with lipid raft microdomains during chemokine exposure may play an important role in chemokine receptor signaling and receptor partitioning with lipid rafts.     

CXCR4 expression affects overall survival of HCC patients whereas CXCR7 expression does not

Hepatocellular carcinoma (HCC) is a heterogeneous disease with a poor prognosis and limited markers for predicting patient survival. Because chemokines and chemokine receptors play numerous and integral roles in HCC disease progression, the CXCR4–CXCL12–CXCR7 axis was studied in HCC patients. CXCR4 and CXCR7 expression was analyzed by immunohistochemistry in 86 HCC patients (training cohort) and validated in 42 unrelated HCC patients (validation cohort). CXCR4 levels were low in 22.1% of patients, intermediate in 30.2%, and high in 47.7%, whereas CXCR7 levels were low in 9.3% of patients, intermediate in 44.2% and high in 46.5% of the patients in the training cohort. When correlated to patient outcome, only CXCR4 affected overall survival (P=0.03). CXCR4–CXCL12–CXCR7 mRNA levels were examined in 33/86 patients. Interestingly, the common CXCR4–CXCR7 ligand CXCL12 was expressed at significantly lower levels in tumor tissues compared to adjacent normal liver (P=0.032). The expression and function of CXCR4 and CXCR7 was also analyzed in several human HCC cell lines. CXCR4 was expressed in Huh7, Hep3B, SNU398, SNU449 and SNU475 cells, whereas CXCR7 was expressed in HepG2, Huh7, SNU449 and SNU475 cells. Huh7, SNU449 and SNU475 cells migrated toward CXCL12, and this migration was inhibited by AMD3100/anti-CXCR4 and by CCX771/anti-CXCR7. Moreover, SNU449 and Huh7 cells exhibited matrix invasion in the presence of CXCL12 and CXCL11, a ligand exclusive to CXCR7. In conclusion, CXCR4 affects the prognosis of HCC patients but CXCR7 does not. Therefore, the CXCR4–CXCL12–CXCR7 axis plays a role in the interaction of HCC with the surrounding normal tissue and represents a suitable therapeutic target.     

CXCL12/CXCR4/CXCR7轴在胎盘滋养细胞中作用机制的探讨

CXCL12介导的信号通路参与调节免疫细胞的活化和募集、造血干细胞的动员和归巢、新生血管形成、胚胎发育、肿瘤侵袭转移等过程.最近,CXCL12/CXCR4/CXCR7生物轴在胎盘植入和发育中的重要作用越来越受到关注.研究发现,CXCL12介导的信号通路参与调节胎盘滋养细胞的分化、增殖和侵袭,同时又可以趋化滋养细胞定向移动到蜕膜间质及血管周围,促进胎盘的植入、子宫-胎盘血管重塑和免疫耐受,进而维持妊娠的正常进行.深入理解CXCL12/CXCR4/CXCR7轴在胎盘滋养细胞中的作用机制,将有助于进一步认识胎盘植入的内在机制,为滋养细胞功能紊乱相关疾病的治疗提供新的思路.     

CXCR3及其配体与自身免疫病的相关研究

趋化因子是一种小分子量蛋白,参与T细胞分化、白细胞迁移、血管再生、肥大细胞脱颗粒等多种免疫功能.趋化因子受体为一种7次跨膜G蛋白耦联受体,趋化因子受体与趋化因子密切联系,共同构成生理及病理情况下复杂的网络系统,参与多种炎症性疾病以及自身免疫性疾病的发生与发展.趋化因子受体CXCR3及其配体,在系统性红斑狼疮(SLE)、...