CXCR4/CXCL12与胃癌生物学行为

胃癌是一种常见恶性肿瘤,总体疗效欠佳,尤其发生腹膜转移者,预后较差.近年来,CXCR4及CXCL12在肿瘤研究中已逐渐成为热点;在胃癌研究中已逐渐见相关报道,如在胃癌生长、迁徙、转移和肿瘤新生血管形成等诸方面均起着重要作用.CXCR4受体拮抗剂在胃癌动物模型中的治疗效果也显示了其应用前景.此文综述了CXCR4/CXCL12在胃癌中作用机制,对CXCR4/CXCL12的深入研究将有望使其成为胃癌靶向治疗的特异靶点.     

Dissecting the role of the CXCL12/CXCR4 axis in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is the most common adult acute leukaemia with the lowest survival rate. It is characterised by a build-up of immature myeloid cells anchored in the protective niche of the bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is central to the pathogenesis of AML as it has fundamental control over AML cell adhesion into the protective BM niche, adaptation to the hypoxic environment, cellular migration and survival. High levels of CXCR4 expression are associated with poor relapse-free and overall survival. The CXCR4 ligand, CXCL12 (SDF-1), is expressed by multiple cells types in the BM, facilitating the adhesion and survival of the malignant clone. Blocking the CXCL12/CXCR4 axis is an attractive therapeutic strategy providing a ‘multi-hit’ therapy that both prevents essential survival signals and releases the AML cells from the BM into the circulation. Once out of the protective niche of the BM they would be more susceptible to destruction by conventional chemotherapeutic drugs. In this review, we disentangle the diverse roles of the CXCL12/CXCR4 axis in AML. We then describe multiple CXCR4 inhibitors, including small molecules, peptides, or monoclonal antibodies, which have been developed to date and their progress in pre-clinical and clinical trials. Finally, the review leads us to the conclusion that there is a need for further investigation into the development of a ‘multi-hit’ therapy that targets several signalling pathways related to AML cell adhesion and maintenance in the BM.     

Disturbed CXCR4/CXCL12 axis in paediatric precursor B‐cell acute lymphoblastic leukaemia

Malignant cells infiltrating the bone marrow (BM) interfere with normal cellular behaviour of supporting cells, thereby creating a malignant niche. We found that CXCR4‐receptor expression was increased in paediatric precursor B‐cell acute lymphoblastic leukaemia (BCP‐ALL) cells compared with normal mononuclear haematopoietic cells (P < 0·0001). Furthermore, high CXCR4‐expression correlated with an unfavourable outcome in BCP‐ALL (5‐year cumulative incidence of relapse ± standard error: 38·4% ± 6·9% in CXCR4‐high versus 12% ± 4·6% in CXCR4‐low expressing cases, P < 0·0001). Interestingly, BM levels of the CXCR4‐ligand (CXCL12) were 2·7‐fold lower (P = 0·005) in diagnostic BCP‐ALL samples compared with non‐leukaemic controls. Induction chemotherapy restored CXCL12 levels to normal. Blocking the CXCR4‐receptor with Plerixafor showed that the lower CXCL12 serum levels at diagnosis could not be explained by consumption by the leukaemic cells, nor did we observe an altered CXCL12‐production capacity of BM‐mesenchymal stromal cells (BM‐MSC) at this time‐point. We rather observed that a very high density of leukaemic cells negatively affected CXCL12‐production by the BM‐MSC while stimulating the secretion levels of granulocyte colony‐stimulating factor (G‐CSF). These results suggest that highly proliferative leukaemic cells are able to down‐regulate secretion of cytokines involved in homing (CXCL12), while simultaneously up‐regulating those involved in haematopoietic mobilization (G‐CSF). Therefore, interference with the CXCR4/CXCL12 axis may be an effective way to mobilize BCP‐ALL cells.     

CXCR4/CXCL12-mediated entrapment of axons at the injury site compromises optic nerve regeneration

Regenerative failure in the mammalian optic nerve is generally attributed to axotomy-induced retinal ganglion cell (RGC) death, an insufficient intrinsic regenerative capacity, and an extrinsic inhibitory environment. Here, we show that a chemoattractive CXCL12/CXCR4-dependent mechanism prevents the extension of growth-stimulated axons into the distal nerve. The chemokine CXCL12 is chemoattractive toward axonal growth cones in an inhibitory environment, and these effects are entirely abolished by the specific knockout of its receptor, CXCR4 (CXCR4^−/−), in cultured regenerating RGCs. Notably, 8% of naïve RGCs express CXCL12 and transport the chemokine along their axons in the nerve. Thus, axotomy causes its release at the injury site. However, most osteopontin-positive α-RGCs, the main neuronal population that survives optic nerve injury, express CXCR4 instead. Thus, CXCL12-mediated attraction prevents growth-stimulated axons from regenerating distally in the nerve, indicated by axons returning to the lesion site. Accordingly, specific depletion of CXCR4 in RGC reduces aberrant axonal growth and enables long-distance regeneration. Likewise, CXCL12 knockout in RGCs fully mimics these CXCR4^−/− effects. Thus, active CXCL12/CXCR4-mediated entrapment of regenerating axons to the injury site contributes to regenerative failure in the optic nerve.

Retinal ganglion cells (RGCs) convey the visual input from the eye through the optic nerve and optic tract into the brain’s target regions. As typical neurons of the central nervous system (CNS), mammalian RGCs lose most of their capability to regrow injured axons after birth (1, 2), leading to an irreversible functional loss after optic nerve damage. To date, regenerative failure has been mainly attributed to three leading causes: 1) axotomy-induced apoptosis of RGCs, 2) the low intrinsic capacity to regrow axons, and 3) the external inhibitory environment with CNS myelin and glial scar proteins (3, 4).One widely used approach to delay axotomy-induced RGC degeneration and activate the intrinsic regenerative capacity of injured axons is inflammatory stimulation (IS) in the eye induced by a lens injury, intravitreal Pam₃Cys, or zymosan injection (5–7). IS leads to the expression and release of CNTF, LIF, and IL-6 from retinal astrocytes and Müller cells (8–10), which directly interact with RGCs and activate neuroprotective/regenerative signaling such as the JAK/STAT3 pathway (8, 9, 11, 12). IS, therefore, enables moderate axon regeneration beyond the lesion site of the optic nerve. Although combinatorial strategies, together with measures overcoming the inhibitory CNS environment synergistically, further improve IS-mediated optic nerve regeneration (13–17), the overall outcome remains mostly unsatisfactory. Thus, additional unknown mechanisms besides neurodegeneration, low intrinsic capacity, and the inhibitory environment might contribute to optic nerve regeneration failure.The chemokine receptor CXCR4, a seven-transmembrane G protein–coupled receptor, is expressed in embryonic and adult neurons (18–20). We have recently shown that this receptor is also expressed in the somata and axons of adult rat RGCs (18). Next to its role as a coreceptor for HIV entry and cancer-cell migration/proliferation (21, 22), CXCR4 is reportedly involved in neurogenesis and axonal pathfinding during the embryonal development of RGCs (20, 23, 24). CXCR4 regulates different signaling pathways upon binding its ligand CXCL12 (also known as stromal cell–derived factor 1, SDF-1), which is part of the chemokine family of chemotactic cytokines in the immune system involved in the attraction of lymphocytes (25, 26). CXCL12 is also reportedly expressed by some CNS neurons, astrocytes, and microglia (19, 27–30). As the CXCR4/CXCL12 axis is highly conserved between different species (31) and involved in axonal pathfinding during embryonal development of RGCs (20, 32), we speculated that CXCR4 expression in adult RGCs might also play a role in the regenerative processes of mature axons.The current study shows that growth-stimulated axons of RGCs are actively attracted and entrapped at the lesion site of the optic nerve by a CXCL12/CXCR4-dependent mechanism. CXCL12 is expressed in a subpopulation of RGCs and axonally transported, implying its release at the injury site. A different RGC subpopulation expressed CXCR4, causing axons in the distal nerve to return to the injury site. Specific depletion of CXCR4 or CXCL12 in RGCs abolished aberrant growth. It enabled long-distance regeneration in the optic nerve, with some axons reaching the optic chiasm 3 wk after injury. Thus, active CXCL12/CXCR4-mediated entrapment markedly compromises axon extension into the distal optic nerve and contributes to regenerative failure in the optic nerve.     

趋化因子CXCL10(IP-10)/CXCR3在类风湿关节炎发病中的作用及应用前景

类风湿关节炎（RA）是一类以关节炎为主要临床表现的系统性自身免疫性疾病。实验证明,T细胞尤其是CD4~＋T细胞的异常活化及其分泌的细胞因子所形成的网络参与了RA激发和延续。趋化因子在炎症细胞向滑膜组织迁移及活化过程中发挥了关键作用,趋化因子C-X-C配体10/干扰素诱导蛋白-10（CXCL10/IP-10）可与表达在T细胞表面的受体趋化因子C-X-C受体3（CXCR3）结合促进其活化并向CD4~＋Th1细胞方向分化,从而促进炎症反应。研究发现,CXCL10在RA血清及滑膜中表达增高。目前作为RA的一个可能的致病因素,CXCL10/CXCR3在发病机制中的作用越来越受到重视。研究发现,CXCL10抗体及裸DNA疫苗可对RA关节炎有抑制及治疗作用,其可能作为RA治疗新靶点的研究日益增多。     

趋化因子CXCL12在缺血性脑卒中的作用及其机制

趋化因子CXCL12及其受体CXCR4参与炎症反应、诱导细胞迁徙和归巢等多种生理和病理过程,且与神经的产生、内分泌及变性等均密切相关。动物实验及临床研究证明,CXCL12及其传导通路在缺血性脑卒中不同时期具有加重损伤及促进功能重建的双重作用,有可能成为预测缺血性脑卒中近期发作及预后的一个新的生物学指标,为脑卒中预防及治疗开创新的途径。     

趋化因子受体CXCR7及其配体CXCLl2、CXCLll与非小细胞肺癌关系

趋化因子受体CXCR7及CXCLl2、CXCLll在生物体中发挥重要作用,尤其在肿瘤细胞生长、增殖、侵袭、转移等过程中的作用成为近年来的研究热点之一。本文就CXCR7、CXCLl2、CXCLll的珲馋和生物学特性及其在非小细胞肺癌中的研究进展和意义进行综述。     

Characterization of the CXCR4 signaling in pancreatic cancer cells

CXCL12 and its receptor, CXCR4, are emerging as promising targets for modulating growth, angiogenesis, and metastasis in several human cancers. Indeed, blocking the receptor is sufficient to prevent metastasis and angiogenesis in experimental breast cancer xenografts. Recently, the biological effect of the CXCR4 in pancreatic cancer, one of the most deadly neoplastic diseases, has been reported. However, the molecular mechanism by which CXCR4 contributes to these properties is not completely understood. In this paper, we characterize the signaling pathways activated by CXCR4 in pancreatic cancer. We show that after CXCR4 activation, EGFR becomes tyrosine phosphorylated, and the kinase activity of this receptor, together with the activation of MMPs, Src, and PI3-Kinase, is required for CXCR4-mediated ERK activation. Analysis of this cascade in pancreatic cancer cells revealed that the ERK-mediated pathway regulates genes involved in angiogenesis, such as VEGF, CD44, HIF1α, and IL-8. Furthermore, ERK blockage inhibits the migration and tube formation of endothelial cells induced by CXCL12. Considering that inhibitors for several components of this pathway, including CXCR4 itself, are at different stages of clinical trials, this study provides theoretical justification for the clinical testing of these drugs in pancreatic cancer, thus extending the list of potential targets for treating this dismal disease.     

Involvement of PI3K and ERK1/2 pathways in hepatocyte growth factor-induced cholangiocarcinoma cell invasion

AIM:To investigate the role of hepatocyte growth factor(HGF) in cholangiocarcinoma(CCA) cell invasiveness and the mechanisms underlying such cellular responses. METHODS:Effects of HGF on cell invasion and motility were investigated in two human CCA cell lines,HuCCA-1 and KKU-M213,using Transwell in vitro assay.Levels of proteins of interest and their phosphorylated forms were determined by Western blotting.Localization of E-cadherin was analyzed by immunofluorescence staining and visualized under confocal m...     

胃癌组织中CXCL12、CXCR4的表达及意义

目的 探讨胃癌组织中趋化因子CXCL12及其受体CXCR4蛋白表达与肿瘤浸润、转移的关系.方法 选择胃癌患者50例,取其癌组织和癌旁正常组织标本,应用免疫组化SP方法,检测CXCL12及CXCR4在胃癌组织、正常黏膜及转移淋巴结中的表达情况.结果 与正常黏膜相比,CXCL12和CXCR4在胃癌组织中的表达升高(P＜0.01),胃癌有淋巴结转移者较无淋巴结转移者表达升高(P＜0.01).结论 胃癌组织中CXCL12与CXCR4的高表达与胃癌的浸润及淋巴结转移有关;CXCL12和CXCR4检测可作为判断胃癌预后的一项指标.     

TIMP-1抑制大鼠肾小球系膜细胞凋亡与磷脂酰肌醇3激酶/丝/苏氨酸激酶通路的研究

目的探讨磷脂酰肌醇3激酶(phosphoinositide-3-kinase,PI3K)/丝/苏氨酸激酶(serine thre-onine kinase,AKT)通路在基质金属蛋白酶组织抑制剂1(tissue inhibitor of metalloproteinase-1,TIMP-1)抑制高糖诱导大鼠肾小球系膜细胞(rat mesangial cells,RMC)凋亡中的作用和机制。方法(1)脂质体法将正、反义人TIMP-1(hTIMP-1)及空载体转染到大鼠肾小球系膜细胞。(2)Annexin V/PI双染法流式检测系膜细胞凋亡率。(3)Caspase9/Mch6Colorimetric Assay试剂盒检测Caspase9活性。(4)Western blot检测BAD、phospho-BAD、AKT、phospho-AKT蛋白水平。结果与对照组(1·06±0·08)%相比,正义转染组细胞凋亡率降低[(4·51±0·50)%,P<0·05],反义转染组凋亡率显著提高[(24·97±3·64)%,P<0·05],LY294002的加入可部分抵消TIMP-1的抗凋亡作用。TIMP-1的高表达可下调Caspase9活性(0·111±0·064,P<0·05),低表达可上调Caspase9活性(0·461±0·012,P<0·05)。正义TIMP-1能提高细胞phos-pho-BAD、phospho-AKT的蛋白水平,而反义TIMP-1的两种蛋白水平明显减少,且该作用可被LY294002阻断。结论(1)PI3K/AKT通路参与TIMP-1抑制高糖诱导的大鼠肾小球系膜细胞凋亡过程。(2)BAD在其中起重要作用。(3)AKT对Caspase9的抑制亦起主要作用。     

The CXCR4 chemokine receptor in acute and chronic leukaemia: a marrow homing receptor and potential therapeutic target

Chemokine (C-X-C motif) receptor 4 (CXCR4) is essential for homing and maintenance of haematopoietic stem cells in distinct stromal cell niches within the marrow. Chemotactic responsiveness of haematopoietic stem cells is restricted to the ligand for CXCR4, stromal cell-derived factor-1 (SDF-1/CXCL12), which is constitutively secreted by marrow stromal cells. Myeloid and lymphoid leukaemia cells also express CXCR4 that induces leukaemia cell chemotaxis and migration beneath marrow stromal cells. CXCR4 expression levels have a major prognostic impact in acute myeloid leukaemia. There is growing in vitro and in vivo evidence that CXCR4 expression by leukaemia cells allows for homing and their retention within the marrow. As such, leukaemia cells appear to utilise CXCR4 to access niches that are normally restricted to progenitor cells, and thereby reside in a microenvironment that favours their growth and survival. CXCR4- and integrin-mediated contact between leukaemia cells and stromal cells protects leukaemia cells from spontaneous and chemotherapy-induced cell death and therefore may represent a mechanism to explain minimal residual disease and subsequent relapses commonly seen in the treatment of these diseases. This review summarises our current knowledge regarding the importance of CXCR4 in acute and chronic leukaemia, discusses the importance of CXCR4 detection by flow cytometry in the diagnostic workup of leukaemia patients, and introduces the potential role of CXCR4-targeting compounds for the treatment of leukaemia patients.     

TBL1XR1 induces cell proliferation and inhibit cell apoptosis by the PI3K/AKT pathway in pancreatic ductal adenocarcinoma

BACKGROUND Pancreatic ductal adenocarcinoma(PDAC) is one of the deadliest solid tumors. Identification of diagnostic and therapeutic biomarkers for PDAC is urgently needed. Transducin(β)-like 1 X-linked receptor 1(TBL1 XR1) has been linked to the progression of various human cancers. Nevertheless, the function and role of TBL1 XR1 in pancreatic cancers are unclear.AIM To elucidate the function and potential mechanism of TBL1 XR1 in the development of PDAC.METHODS Ninety patients with histologically-confirmed PDAC were included in this study. PDAC tumor samples and cell lines were used to determine the expression of TBL1 XR1. CCK-8 assays and colony formation assays were carried out to assess PDAC cell viability. Flow cytometry was performed to measure the changes in the cell cycle and cell apoptosis. Changes in related protein expression were measured by western blot analysis. Animal analysis was conducted to confirm the impact of TBL1 XR1 in vivo.RESULTS Patients with TBL1 XR1-positive tumors had worse overall survival than those with TBL1 XR1-negative tumors. Moreover, we found that TBL1 XR1 strongly promoted PDAC cell proliferation and inhibited PDAC cell apoptosis. Moreover, knockdown of TBL1 XR1 induced G0/G1 phase arrest. In vivo animal studies confirmed that TBL1 XR1 accelerated tumor cell growth. The results of western blot analysis showed that TBL1 XR1 might play a key role in regulating PDAC cell proliferation and apoptosis via the PI3 K/AKT pathway.CONCLUSION TBL1 XR1 promoted PDAC cell progression and might be an effective diagnostic and therapeutic marker for pancreatic cancer.     

CXCR4 chemokine receptors (CD184) and alpha4beta1 integrins mediate spontaneous migration of human CD34+ progenitors and acute myeloid leukaemia cells beneath marrow stromal cells (pseudoemperipolesis)

Marrow stromal cells play an important role in regulating the development and proliferation of haematopoietic stem cells (HSC) within the marrow microenvironment. However, the molecular mechanisms of stem cell-stromal cell interactions are not fully understood. We observed that mobilized peripheral blood and cord-blood-derived CD34+ progenitor cells, or CD34+ acute myeloid leukaemia (AML) cells spontaneously migrated beneath marrow stromal cells, an in vitro migration phenomenon termed pseudoemperipolesis. In contrast, the CD34+ myeloid leukaemia cell line, Kasumi-1, did not display pseudoemperipolesis. Cord blood CD34+ cells had a higher capacity than granulocyte-colony-stimulating-factor-mobilized CD34+ cells for pseudoemperipolesis (28.7 +/- 12%vs 18.1 +/- 6.1% of input cells within 24 h, mean +/- SD, n = 8), whereas 9.4 +/- 12.6% (mean +/- SD, n = 10) of input AML cells displayed this phenomenon. Pseudoemperipolesis of CD34+ progenitor and AML cells was significantly inhibited by pertussis toxin and antibodies to the CXCR4 chemokine receptor (CXCR4, CD184), but not control antibodies. Moreover, CD34+ and AML cell migration was significantly inhibited by a CS1 peptide that blocks alpha4beta1 integrin binding, but not by a control peptide, in which the fibronectin binding motif was scrambled. Pseudoemperipolesis was associated with an increased proliferation of migrated CD34+ progenitor cells but not AML cells within the stromal layer, demonstrated by cell cycle analysis and cell division tracking. We conclude that alpha4beta1 integrin binding and CXCR4 chemokine receptor activation are prerequisites for the migration of CD34+ haematopoietic progenitors and AML cells beneath marrow stromal cells. These observations suggest a central role of marrow stromal cells for HSC trafficking and homing within the marrow microenvironment.     

CXCL10与CXCR3在ARDS中的研究进展

CXC趋化因子配体10 (CXCL10)又称γ干扰素诱导蛋白10 (IP-10),属于CXC类非ELR亚族趋化因子之一,是γ干扰素诱导产生的可以趋化多种炎症细胞如T淋巴细胞,单核细胞和自然杀伤细胞的一类蛋白质.CXCL10通过与特异性CXC趋化因子受体3(CXCR3)结合调节炎症反应,促进ARDS的病理过程.本文旨在阐述CXCL10与CXCR3在ARDS中的作用,为ARDS的治疗提供新思路.     

IGF-1对Aβ25-35致PC12细胞损伤的保护作用及其机制的探讨

目的探讨胰岛素样生长因子1(IGF-1)对β样淀粉蛋白(Aβ25-35)引起的PC12细胞凋亡及tau蛋白磷酸化的保护作用及其机制。方法采用MTT,TUNEL等检测磷酸化Akt、Akt水平及Tau蛋白磷酸化水平,观察IGF-1对Aβ25-35致PC12细胞的损伤保护作用。结果MTT分析法表明IGF-1保护组的细胞活性显著高于Aβ损伤组(P<0.01),TUNEL法检测结果显示IGF-1保护组凋亡指数低于Aβ损伤组(P<0.01),IGF-1保护组能使被Aβ下调的磷酸化Akt水平恢复至与对照组相近的水平,总Akt水平基本维持不变。IGF-1保护组tau蛋白在Ser396,Ser202位点的磷酸化水平和总tau蛋白水平均明显低于Aβ损伤组。结论IGF-1能降低Aβ的细胞毒性,抑制Aβ25-35诱导的PC12细胞的凋亡和tau蛋白磷酸化,这一作用机制是通过PI3K/Akt信号传导途径来实现的。