卵巢肿瘤干细胞中趋化因子的表达与细胞侵袭转移能力的关系

目的探讨卵巢肿瘤干细胞中趋化因子的表达与细胞侵袭转移能力的关系,为卵巢肿瘤的治疗提供新的研究思路和药物作用靶点。方法采用流式细胞术与RT-PCR方法检测卵巢肿瘤干细胞系CAOV-3中CXCR4的表达,通过体外微孔隔离室（Transwell）检测CXCR4对CAOV-3细胞侵袭转移能力的影响。结果 CXCR4在CAOV-3中细胞呈阳性表达,CXCL12可促进CAOV-3细胞的迁移,CXCR4的封闭能抑制CXCL12对CAOV-3迁移的促进作用。结论 CXCL12-CXCR4相互作用可促进卵巢肿瘤干细胞侵袭转移,在卵巢肿瘤的生长和侵袭转移过程中起着重要作用。     

CXCR4 inhibitors: tumor vasculature and therapeutic challenges

CXCL12, also known as SDF-1, is the single natural ligand for chemokine receptors CXCR4 and CXCR7. CXCL12 has angiogenic properties in normal endothelial tissue and is involved in the outgrowth and metastasis of CXCR4 expressing tumors. Recent investigations have indicated that CXCL12 levels increase after chemo- and anti- VEGF therapy, favouring recurrences. The blockade of CXCL12/CXCR4 axis has emerged as a potential additional or alternative target for neo-adjuvant treatments. We have reviewed recent patent applications between 2008 and 2011 in tumor angiogenesis and the most clinical data supporting the potential use of anti-CXCR4 agents in this field. Among these, AMD3100, also known as Plerixaform (Mozobil by Genzyme), is approved for stem cell mobilisation in patients with leukaemia, while BKT140 (Emory University), POL6326 (Polyphor Ag) and TG-0054 (ChemoCentryx) are currently in clinical trials in combination with chemotherapy for multiple myeloma and leukaemia. The aptamer Nox-A12 (Noxxon) is in trials for chronic lymphatic leukaemia treatment. MSX-122 (Metastatix) is in Phase I trials for solid tumor treatment, while CXCR7-specific inhibitor CCX2066 (ChemoCentryx) is still in preclinical studies. We have also considered other strategies, such RNA interference and miRNA, which could be tested for solid tumor adjuvant therapy.     

CXCR4 chemokine receptor antagonists: perspectives in SCLC

Small-cell lung cancer (SCLC) is a particularly aggressive form of lung cancer characterized by early and widespread metastases and the ability to rapidly develop resistance against chemotherapeutic agents. Tumor cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokine receptors and adhesion molecules. SCLC cells express high levels of CXCR4 (CD184), a seven-transmembrane G-protein-coupled chemokine receptor. Stromal cells within the bone marrow microenvironment and at extramedullary sites constitutively secrete stromal cell-derived factor-1 (CXCL12), the ligand for CXCR4. Activation of CXCR4 induces SCLC cell migration and adhesion to stromal cells that secrete CXCL12, which in turn provides growth- and drug resistance-signals to the tumor cells. CXCR4 antagonists, such as Plerixafor (AMD3100) and T140 analogues (TN14003/ BKT140), disrupt CXCR4-mediated SCLC cell-adhesion to stromal cells. In stromal cell co-cultures, CXCR4 antagonists also sensitize SCLC cells to cytotoxic drugs, such as etoposide, and thereby antagonize cell adhesion-mediated drug resistance. Therefore, targeting the CXCR4–CXCL12 axis is a novel, attractive therapeutic approach in SCLC. Here, we summarize preclinical data about CXCR4 in SCLC, and the current status of the preclinical and clinical development of CXCR4 antagonists.     

The CXCL12/CXCR4 axis as a therapeutic target in cancer and HIV-1 infection

The seven-spanning transmembrane G-protein coupled receptor CXCR4, which specifically binds to the chemokine CXCL12, is expressed on many cell types, including various types of tumour cells. CXCR4 plays a crucial role in organ-specific metastasis, directing migration of malignant cells expressing this receptor toward microenvironments where the cognate ligand is secreted. CXCL12 has a direct growth and survival-promoting effect for various cancer cells and enhances moreover tumour angiogenesis by recruiting endothelial progenitor cells to tumours. Drugs which modulate the CXCL12/CXCR4 axis are therefore promising candidates in anti-cancer therapies. CXCR4 is also a coreceptor for human immunodeficiency virus type 1 (HIV-1) X4 virus and, as such, plays an important role in virus entry into target cells. Hence, antiviral agents that bind to CXCR4 are expected to inhibit HIV-1 entry. Here we review the structure, mechanism of action and biological activity of the main CXCR4 antagonists (peptide inhibitors, non-peptide antagonists, neutralizing antibodies, modified analogues of CXCL12) and agonists (CXCL12 peptide analogues) and discuss the CXCL12/CXCR4 axis as an important target in development of anti-tumoral and anti-HIV-1 therapies.     

Integrin/Chemokine Receptor Interactions in the Pathogenesis of Experimental Autoimmune Encephalomyelitis

Excessive infiltration of leukocytes and the elaboration of inflammatory cytokines are believed to be responsible for the observed damage to neurons and oligodendrocytes during multiple sclerosis (MS). Blocking adhesion molecules or preventing the effects of chemotactic mediators such as chemokines can be exploited to prevent immune cell recruitment to inflamed tissues. An anti-α4 integrin antibody (anti-VLA-4mAb/natalizumab (Tysabri®)) has been used as a treatment for MS and reduces leukocyte influx into the brain. In patients, anti-VLA-4 reduces relapses and disability progression. However, its mechanism of action in the brain is not completely understood. The anti-VLA-4mAb was demonstrated to mobilize hematopoietic progenitor cells. Interestingly, the chemokine SDF-1/CXCL12 and its receptor CXCR4 are also key factors regulating the migration of hematopoietic stem cells. Moreover, studies have revealed a crosstalk between SDF-1/CXCR4 and VLA-4 signaling in regulating cell migration. In this study, we address the effects of anti-VLA-4 on chemokine signaling in the brain during MS. We assessed the ability of anti-VLA-4 to regulate Experimental Autoimmune Encephalomyelitis (EAE) and chemokine/receptor signaling. Preclinical administration of anti-VLA-4 delayed clinical signs of EAE. We found that anti-VLA-4 treatment reduced chemokine expression. In order to further explore the interaction of anti-VLA-4 with chemokine/receptor signaling we used dual color transgenic mice. After EAE induction, the expression of both SDF-1/CXCL12 and CXCR4 receptor was upregulated, treatment with anti-VLA-4 inhibited this effect. The effects of anti-VLA-4 on chemokine signaling in the CNS may be of importance when considering its mechanism of action and understanding the pathogenesis of EAE.     

The therapeutic potential of CXCR4 antagonists in the treatment of HIV infection, cancer metastasis and rheumatoid arthritis

CXCR4 is the receptor of the chemokine CXCL12, which is involved in progression and metastasis of several types of cancer cells, HIV infection and rheumatoid arthritis. The authors developed selective CXCR4 antagonists, T22 and T140, initially as anti-HIV agents, which inhibit T cell line-tropic (X4-) HIV-1 infection through their specific binding to CXCR4. Recently, T140 analogues have also been shown to inhibit CXCL12-induced migration of breast cancer cells, leukaemia T cells, pancreatic cancer cells, small cell lung cancer cells, chronic lymphocytic leukaemia B cells, pre-B acute lymphoblastic leukaemia cells and so on in vitro. Biostable T140 analogues significantly suppressed pulmonary metastasis of breast cancer cells and melanoma cells in mice. Furthermore, these compounds significantly suppressed the delayed-type hypersensitivity response induced by sheep red blood cells and collagen-induced arthritis, which represent in vivo mouse models of arthritis. Thus, T140 analogues proved to be attractive lead compounds for chemotherapy of these problematic diseases. This article reviews recent research on T140 analogues, referring to several other CXCR4 antagonists.     

A proposed mechanism for the protective effect of dioxin against breast cancer.

Although it is causative for many types of cancers, experimental and epidemiological evidence suggest that 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) may in fact protect against breast cancer. The mechanism(s) for this protection remain unclear. In an attempt to further elucidate this mechanism, we performed a microarray experiment to identify genes that were modulated upon dioxin treatment. We found that dioxin downregulated the messenger RNAs for the G-protein-coupled receptor, CXCR4, as well as its unique chemokine ligand, CXCL12, in MCF-7 breast cancer cells. We demonstrated that the corresponding proteins are also downregulated by dioxin. The interaction between CXCR4 and CXCL12 plays a central role in the metastasis of breast cancer, as disruption of the CXCL12/CXCR4 axis has been shown to limit the metastasis of breast cancer cells to the lung in mice. Utilizing an in vitro chemotaxis assay, we demonstrate that dioxin specifically inhibits the migration of MCF-7 cells toward CXCL12. We also show that dioxin reduces CXCR4 under hypoxia and CXCL12 under estradiol-induced conditions in MCF-7 cells. Finally, as the CXCR4/CXCL12 axis is implicated in the progression of numerous types of cancer, we identified several other cancer cell lines in which dioxin modulates CXCR4 and CXCL12 levels. We therefore propose that one mechanism whereby dioxin may protect against breast cancer is via downregulation of CXCR4 and CXCL12, thereby inhibiting progression of the disease. Further, other nontoxic ligands for the aryl hydrocarbon receptor (selective AHR modulators) may exert their protective effects by a similar mechanism.     

Roles of chemokine CXCL12 and its receptors in ischemic stroke

Chemokine CXC ligand 12 (CXCL12), originally named stromal cell-derived factor-1 (SDF-1), is a member of the CXC chemokine subfamily. CXCL12 is found to be expressed by all cell types that are presented in the central nervous system (CNS). It works in conjunction with the G-protein coupled receptor CXCR4, which is found at the surface of a variety of cells including neurons, astrocytes, microglia, bone marrow-derived cells, as well as other progenitor cells. Recent studies revealed that CXCL12 could also bind and signal through receptor CXCR7. CXCL12 and CXCR4 are constitutively expressed in the brain but are up-regulated in the ischemic penumbra regions following ischemic stroke. CXCL12/CXCR4 play important roles in multiple processes after ischemic stroke, which include inflammatory response, focal angiogenesis, and the recruitment of bone marrow-derived cells (BMCs) and neural progenitor cell (NPC) to injury. In addition to its roles in stroke pathology, CXCL12 is also thought to be a key regulator in stroke repairing. This review will focus on the function of CXCL12/CXCR4 in post-stroke inflammation and neurovascular repairing. The potential application of CXCL12 modulation in clinical stroke treatment is also discussed.     

The therapeutic potential of CXCR4 antagonists in the treatment of HIV infection,cancer metastasis and rheumatoid arthritis

CXCR4 is the receptor of the chemokine CXCL12, which is involved in progression and metastasis of several types of cancer cells, HIV infection and rheumatoid arthritis. The authors developed selective CXCR4 antagonists, T22 and T140, initially as anti-HIV agents, which inhibit T cell line-tropic (X4-) HIV-1 infection through their specific binding to CXCR4. Recently, T140 analogues have also been shown to inhibit CXCL12-induced migration of breast cancer cells, leukaemia T cells, pancreatic cancer cells, small cell lung cancer cells, chronic lymphocytic leukaemia B cells, pre-B acute lymphoblastic leukaemia cells and so on in vitro. Biostable T140 analogues significantly suppressed pulmonary metastasis of breast cancer cells and melanoma cells in mice. Furthermore, these compounds significantly suppressed the delayed-type hypersensitivity response induced by sheep red blood cells and collagen-induced arthritis, which represent in vivo mouse models of arthritis. Thus, T140 analogues proved to be attractive lead compounds for chemotherapy of these problematic diseases. This article reviews recent research on T140 analogues, referring to several other CXCR4 antagonists.     

趋化因子CXCL12/CXCR4在非小细胞肺癌中的表达

目的:探讨趋化因子CXCL12及其受体CXCR4在非小细胞肺癌(NSCLC)中的表达及与临床病理特征间的关系。方法:采用免疫组织化学SP三步法检测95例NSCLC患者肿瘤组织及27例肺部良性肿瘤患者(对照组)的石蜡标本中CXCL12、CXCR4的表达情况,并比较其在不同临床病理参数患者间表达的差异。结果:对照组中,CXCL12和CXCR4的高表达率分别为0和7.4%(2/27),NSCLC患者的高表达率分别为54.7%(52/95)和42.1%(40/95),差异均有统计学意义(P<0.01)。在NSCLC中,淋巴结转移组的CXCL12和CXCR4的高表达率(67.2%、51.7%)均高于非转移组(35.1%、27.0%),差异均有统计学意义(P<0.05)。CXCL12、CXCR4的高表达率均随TNM分期的增高而逐渐增高,且Ⅲ期的高表达率明显高于Ⅰ期,差异有统计学意义(P<0.01)。NSCLC患者CXCL12与CXCR4之间无明显相关性。不同年龄、性别、肿瘤大小、组织学分型及分化程度NSCLC患者之间CXCL12、CXCR4的高表达率差异无统计学意义(P>0.05)。结论:CXCL12、CXCR4的表达水平可作为判断NSCLC预后的参考指标。     

Characterization of the molecular pharmacology of AMD3100: a specific antagonist of the G-protein coupled chemokine receptor, CXCR4

The chemokine receptor CXCR4 is widely expressed on different cell types, is involved in leukocyte chemotaxis, and is a co-receptor for HIV. AMD3100 has been shown to be a CXCR4 receptor antagonist, and to block HIV infection of T-tropic, X4-using, virus in vitro and in vivo. AMD3100 is an effective mobilizer of hematopoietic stem cells and is being investigated in clinical trials in multiple myeloma and non-Hodgkins lymphoma patients. Using the CCRF-CEM T-cell line that constitutively expresses CXCR4 we confirmed that AMD3100 was an antagonist of SDF-1/CXCL12 ligand binding (IC50=651+/-37 nM). We have also shown that AMD3100 inhibits SDF-1 mediated GTP-binding (IC50=27+/-2.2 nM), SDF-1 mediated calcium flux (IC50=572+/-190 nM), and SDF-1 stimulated chemotaxis (IC50=51+/-17 nM). AMD3100 did not inhibit calcium flux against cells expressing CXCR3, CCR1, CCR2b, CCR4, CCR5 or CCR7 when stimulated with their cognate ligands, nor did it inhibit receptor binding of LTB4. AMD3100 did not, on its own, induce a calcium flux in the CCRF-CEM cells, which express multiple GPCRs including CXCR4, CCR4 and CCR7. Furthermore, AMD3100 neither stimulated GTP-binding, an assay for GPCR activation, in CEM cell membranes; nor chemotaxis of CCRF-CEM cells. These data therefore demonstrate that AMD3100 is a specific antagonist of CXCR4, is not cross-reactive with other chemokine receptors, and is not an agonist of CXCR4.     

Development of novel CXCR4-based therapeutics

Introduction: During embryogenesis, CXCR4, a chemokine receptor, and its ligand, stromal cell-derived factor-1 (SDF-1/CXCL12), are critically involved in the development of the hematopoietic, nerve and endothelial tissues by regulating tissue progenitor cell migration, homing and survival. In adult life, the CXCR4 axis serves as the key factor for stem and immune cell trafficking. More importantly, CXCR4–CXCL12 axis plays a critical role in HIV, stem cell mobilization, autoimmune diseases, cancer and tissue regeneration. Targeting the CXCR4–CXCL12 axis, therefore, is an attractive therapeutic approach in various diseases.

Areas covered: In this review, we update current knowledge about CXCR4–CXCL12 biology, therapeutic approaches and therapeutic agents. The data presented was collected from http://www.ncbi.nlm.nih.gov/pubmed, http://clinicaltrials.gov/, http://bloodjournal.hematologylibrary.org/.

Expert opinion: Development of CXCR4 antagonists with increased affinity, extended pharmacokinetics and/or pharmacodynamics and with the capacity to differentially target CXCR4 may lead to a development of novel therapeutics for HIV, cancer, tissue regeneration and stem cell collection.     

Modulating the interaction of CXCR4 and CXCL12 by low-molecular-weight heparin inhibits hepatic metastasis of colon cancer

Liver metastasis is the major obstacle for prolonging the survival of colon cancer patients. Low-molecular-weight heparin (LMWH), a common drug for venous thromboembolism, has displayed beneficial effects in improving the survival of cancer patients, though the mechanism remains unclear. This study aimed to investigate the effects of LMWH on hepatic metastasis of colon cancer and its underlying molecular mechanism by targeting the interaction of the chemokine receptor CXCR4 and its ligand CXCL12 (formerly known as stromal cell-derived factor 1α, SDF-1α), as the CXCR4-CXCL12 axis has been shown to regulate the interaction of cancer cells and stroma. Experimental results revealed that LMWH (Enoxaparin, 3500–5500 Da) inhibited the CXCL12-stimulated proliferation, adhesion and colony formation of human colon cancer HCT-116 cells that highly expressed CXCR4. Interestingly, LMWH or an anti-CXCR4 blocking antibody diminished the migrating and invading abilities of HCT116 cells stimulated by the recombinant CXCL12 protein or liver homogenates which contained endogenous CXCL12 protein. Although LMWH did not significantly inhibit the growth of subcutaneous colon tumors, it significantly suppressed the formation of hepatic metastasis established by intrasplenic injection of colon cancer cells in nude Balb/c mice and also downregulated the expression of CXCL12 in hepatic sinusoidal endothelial cells. The results suggest that LMWH inhibits the formation of hepatic metastasis of colon cancer by disrupting the interaction of CXCR4 and CXCL12, supporting that perioperative administration of LMWH may help to prevent the seeding and subsequent growth of hepatic metastases of colon cancer cells.     

Lymphoproliferative disorders and chemokines

Chemokines are low molecular weight cytokines specialized in leukocyte recruitment. Recent studies have shown that tumor cells of hematopoietic and non hematopoietic origin express different chemokine receptors that may be involved in neoplastic cell growth, metastasis and angiogenesis. Human lymphoproliferative disorders arise from the malignant transformation of normal lymphoid cells frozen at discrete maturational stages. Studies performed with acute or chronic lymphoproliferative disorders have shown that CXCR4, the unique receptor for CXCL12, is up-regulated in many B and T cells malignancies and may be involved in metastatic localization of the neoplastic elements. Additional chemokine receptors are expressed in the individual lymphoproliferative disorders, but some of these are often non functional. Here we shall review the state of the art on chemokine receptor expression and function in human lymphoproliferative disorders, stressing the potential value of chemokines receptors as novel therapeutic targets. In this respect, small antagonistic peptides are being produced by pharmaceutical companies and hold great promise for clinical application.     

Therapeutic targeting of microenvironmental interactions in leukemia: Mechanisms and approaches

In hematological malignancies, there are dynamic interactions between leukemic cells and cells of the bone marrow microenvironment. Specific niches within the bone marrow microenvironment provide a sanctuary for subpopulations of leukemic cells to evade chemotherapy-induced death and allow acquisition of a drug-resistant phenotype. This review focuses on molecular and cellular biology of the normal hematopoietic stem cell and the leukemia stem cell niche, and of the molecular pathways critical for microenvironment/leukemia interactions. The key emerging therapeutic targets include chemokine receptors (CXCR4), adhesion molecules (VLA4 and CD44), and hypoxia-related proteins HIF-1α and VEGF. Finally, the genetic and epigenetic abnormalities of leukemia-associated stroma will be discussed. This complex interplay provides a rationale for appropriately tailored molecular therapies targeting not only leukemic cells but also their microenvironment to ensure improved outcomes in leukemia.     

Development of novel CXCR4-based therapeutics

INTRODUCTION: During embryogenesis, CXCR4, a chemokine receptor, and its ligand, stromal cell-derived factor-1 (SDF-1/CXCL12), are critically involved in the development of the hematopoietic, nerve and endothelial tissues by regulating tissue progenitor cell migration, homing and survival. In adult life, the CXCR4 axis serves as the key factor for stem and immune cell trafficking. More importantly, CXCR4-CXCL12 axis plays a critical role in HIV, stem cell mobilization, autoimmune diseases, cancer and tissue regeneration. Targeting the CXCR4-CXCL12 axis, therefore, is an attractive therapeutic approach in various diseases. AREAS COVERED: In this review, we update current knowledge about CXCR4-CXCL12 biology, therapeutic approaches and therapeutic agents. The data presented was collected from http://www.ncbi.nlm.nih.gov/pubmed , http://clinicaltrials.gov/ , http://bloodjournal.hematologylibrary.org/ . EXPERT OPINION: Development of CXCR4 antagonists with increased affinity, extended pharmacokinetics and/or pharmacodynamics and with the capacity to differentially target CXCR4 may lead to a development of novel therapeutics for HIV, cancer, tissue regeneration and stem cell collection.     

Inhibition of CXCL12/CXCR4 autocrine/paracrine loop reduces viability of human glioblastoma stem-like cells affecting self-renewal activity

Cancer stem cells (CSCs) or tumor initiating cells (TICs) drive glioblastoma (GBM) development, invasiveness and drug resistance. Distinct molecular pathways might regulate CSC biology as compared to cells in the bulk tumor mass, representing potential therapeutic targets. Chemokine CXCL12 and its receptor CXCR4 control proliferation, invasion and angiogenesis in GBM cell lines and primary cultures, but little is known about their activity in GBM CSCs. We demonstrate that CSCs, isolated from five human GBMs, express CXCR4 and release CXCL12 in vitro, although different levels of expression and secretion were observed in individual cultures, as expected for the heterogeneity of GBMs.CXCL12 treatment induced Akt-mediated significant pro-survival and self-renewal activities, while proliferation was induced at low extent. The role of CXCR4 signaling in CSC survival and self-renewal was further demonstrated using the CXCR4 antagonist AMD3100 that reduced self-renewal and survival with greater efficacy in the cultures that released higher CXCL12 amounts. The specificity of CXCL12 in sustaining CSC survival was demonstrated by the lack of AMD3100-dependent inhibition of viability in differentiated cells derived from the same GBMs.These findings, although performed on a limited number of tumor samples, suggest that the CXCL12/CXCR4 interaction mediates survival and self-renewal in GBM CSCs with high selectivity, thus emerging as a candidate system responsible for maintenance of cancer progenitors, and providing survival benefits to the tumor.