CXCR4 Antagonist AMD3100 Research Articles

CXCR4 antagonist AMD3100 reverses the neurogenesis and behavioral recovery promoted by forced limb-use in stroke rats.

Forced limb-use can enhance neurogenesis and behavioral recovery as well as increasing the level of stromal cell-derived factor-1 (SDF-1) in stroke rats. We examined whether the SDF-1/CXCR4 pathway is involved in the enhanced neurogenesis and promoted behavioral recovery induced by forced limb-use in the chronic phase of stroke. The CXCR4 antagonist, AMD3100, was used to block the SDF-1/CXCR4 pathway in the ischemic rats. Brain ischemia was induced by endothelin-1. One week after ischemia, the unimpaired forelimb of rats was immobilized for 3 weeks. The proliferation, migration, and survival of DCX-positive cells in the subventricular zone (SVZ), and the dendritic complexity of DCX-positive cells in the dentate gyrus (DG), as well as the inflammatory response in the infarcted striatum were analyzed by immunohistochemistry. Functional recovery was assessed in beam-walking and water maze tests. Forced limb-use enhanced the proliferation, migration, dendritic complexity and the survival of newborn neurons. Furthermore, forced limb-use suppressed the inflammatory response and improved both motor and cognitive functions after stroke. AMD3100 significantly abrogated the enhanced neurogenesis and behavioral recovery induced by forced limb-use without influencing the inflammatory response. SDF-1/CXCR4 pathway seems to be involved in the enhancement of neurogenesis and behavioral recovery induced by post-stroke forced limb-use.

Diversity and Inter-Connections in the CXCR4 Chemokine Receptor/Ligand Family: Molecular Perspectives.

CXCR4 and its ligand CXCL12 mediate the homing of progenitor cells in the bone marrow and their recruitment to sites of injury, as well as affect processes such as cell arrest, survival, and angiogenesis. CXCL12 was long thought to be the sole CXCR4 ligand, but more recently the atypical chemokine macrophage migration inhibitory factor (MIF) was identified as an alternative, non-cognate ligand for CXCR4 and shown to mediate chemotaxis and arrest of CXCR4-expressing T-cells. This has complicated the understanding of CXCR4-mediated signaling and associated biological processes. Compared to CXCL12/CXCR4-induced signaling, only few details are known on MIF/CXCR4-mediated signaling and it remains unclear to which extent MIF and CXCL12 reciprocally influence CXCR4 binding and signaling. Furthermore, the atypical chemokine receptor 3 (ACKR3) (previously CXCR7) has added to the complexity of CXCR4 signaling due to its ability to bind CXCL12 and MIF, and to evoke CXCL12- and MIF-triggered signaling independently of CXCR4. Also, extracellular ubiquitin (eUb) and the viral protein gp120 (HIV) have been reported as CXCR4 ligands, whereas viral chemokine vMIP-II (Herpesvirus) and human β3-defensin (HBD-3) have been identified as CXCR4 antagonists. This review will provide insight into the diversity and inter-connections in the CXCR4 receptor/ligand family. We will discuss signaling pathways initiated by binding of CXCL12 vs. MIF to CXCR4, elaborate on how ACKR3 affects CXCR4 signaling, and summarize biological functions of CXCR4 signaling mediated by CXCL12 or MIF. Also, we will discuss eUb and gp120 as alternative ligands for CXCR4, and describe vMIP-II and HBD-3 as antagonists for CXCR4. Detailed insight into biological effects of CXCR4 signaling und underlying mechanisms, including diversity of CXCR4 ligands and inter-connections with other (chemokine) receptors, is clinically important, as the CXCR4 antagonist AMD3100 has been approved as stem cell mobilizer in specific disease settings.

Tetramethylpyrazine (TMP), an Active Ingredient of Chinese Herb Medicine Chuanxiong, Attenuates the Degeneration of Trabecular Meshwork through SDF-1/CXCR4 Axis.

BackgroundA traditional Chinese medicine, Tetramethylpyrazine (TMP), has been prescribed as a complementary treatment for glaucoma to improve patient prognosis. However, the pharmacological mechanism of action of TMP is poorly understood. In previous studies, we demonstrated that TMP exerts potent inhibitory effects on neovascularization, suppresses the tumorigenic behavior of glioma cells, and protects neural cells by regulating CXCR4 expression. Here, we further investigated whether the SDF-1/CXCR4 pathway is also involved in the TMP-mediated activity in trabecular meshwork cells.Methodology/Principal FindingsCXCR4 expression was examined by quantitative real-time PCR in trabecular and iris specimens from 54 primary open-angle glaucoma (POAG) patients who required surgery and 19 non-glaucomatous donors. Our data revealed markedly elevated CXCR4 expression in the trabecular meshwork of POAG patients compared with that of controls. Consistently, CXCR4 expression was much higher in glaucomatous trabecular meshwork cells than in normal trabecular meshwork cells. Using RT-PCR and western blot assays, we determined that glaucoma-related cytokines and dexamethasone (DEX) also significantly up-regulated CXCR4 expression in primary human trabecular meshwork (PHTM) cells. Moreover, the TGF-β1-mediated induction of CXCR4 expression in PHTM cells was markedly down-regulated by TMP compared with control treatment (PBS) and the CXCR4 antagonist AMD3100. In addition, TMP could counteract the TGF-β1-induced effects on stress fiber accumulation and expansion of PHTM cells. TMP markedly suppressed the migration of PHTM cells stimulated by TGF-β1 in transwell and scratch wound assays. TMP also suppressed the extracellular matrix (ECM) accumulation induced by TGF-β2.ConclusionsOur findings demonstrate that CXCR4 might be involved in the pathogenetic changes in the trabecular meshwork of patients with POAG. Additionally, TMP might exert its beneficial effects in POAG patients by down-regulating CXCR4 expression.

Abstract 4155: Interstitial fluid flow-induced hepatocellular carcinoma cell invasion requires MEK/ERK signaling

Abstract Background: Worldwide hepatocellular carcinoma (HCC) is the third leading cancer-related cause of death. Within the United States, HCC maintains a rising incidence rate of 3% each year since 1992 with a 5 year survival rate of less than 15%. The American Cancer Society has estimated 33,190 new cases off HCC and 23,000 HCC related deaths in the year 2014 within the United States. Our work aims to determine the role of biomechanical forces such as interstitial fluid flow (IFF) in HCC cell invasion. We hypothesized that HCC cells utilize the hypothesized ‘autologous chemotaxis’ mechanism to invade via secretion of the chemokine CXCL12 and expression of its receptor CXCR4. Autologous chemotaxis occurs when a biologically significant chemokine gradient is established by IFF, driving downstream invasion. In an effort to elucidate signaling pathways involved in IFF-induced HCC invasion, we have identified a potential role for MEK/ERK signaling. Materials and Methods: HCC cells or primary rat hepatocytes (PRH) were seeded into in a 3-D matrix composed of Matrigel and type I rat tail collagen, then exposed to static or interstitial flow conditions for 24 hours. The functional role of CXCR4 was tested using the CXCR4-antagonist AMD3100. MEK and ERK were inhibited using U0126 (25 μM) and FR180294 (10 μM), respectively. Phospho-MEK/ERK was assessed using western blot. Results and Discussion: The 3D invasion assay demonstrated that the HCC cells, Huh7 and Hep3B, invaded significantly more in response to IFF (5.5 fold increase in invasion compared to their respective static condition), while PRHs showed no response. AMD3100 was used to block the CXCR4 receptor which resulted in reduced invasion in Huh7 and Hep3B cells. Furthermore when U0126 and FR180204 were incorporated into the 3D invasion assay a significant reduction in flow-induced invasion was observed in Huh7 cells. However, interstitial flow or CXCR4 inhibition did not affect pMEK/ERK, suggesting that MEK/ERK are not modulated directly by IFF and are not downstream of CXCR4. Conclusion: Our results demonstrate that interstitial fluid flow stimulates HCC cell invasion. CXCR4/CXCL12 signaling and MEK/ERK signaling both are required for invasion, but appear to operate via separate mechanisms. Further investigation into these two separate mechanisms would provide better insight into flow-induced HCC invasion. This information could potentially enhance current cancer therapies and provide patients with better treatment options. Citation Format: Arpit D. Shah, Michael Bouchard, Adrian C. Shieh. Interstitial fluid flow-induced hepatocellular carcinoma cell invasion requires MEK/ERK signaling. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4155. doi:10.1158/1538-7445.AM2015-4155

Abstract 3676: Attenuation of pancreatic cancer stemness and growth by a novel magnetic nanoparticle formulation

Abstract Background: Pancreatic cancer (PanCa) is one of the deadliest cancers accounting for high mortality rates due to high desmoplasia and the development of chemo-resistance to chemotherapeutic drugs, such as gemcitabine (GEM). Curcumin (CUR) has showed potent anticancer, chemopreventive, chemo-sensitization properties and has entered phase II clinical trials in pancreatic adenocarcinoma patients. However, the clinical translation of CUR has been significantly hampered due to its low solubility, high rate of metabolism, poor bioavailability and pharmacokinetics. To address these clinically relevant issues, we have successfully engineered a magnetic nanoparticle formulation of curcumin (MNP-CUR) using a multi-layer approach, for its efficient and tumor targeted delivery. Methods: Western blotting and qPCR were used to investigate the effects of MNP-CUR, GEM and their combination on Hh signaling pathway and related proteins involved in PanCa. The antitumor effects were studied using PanCa xenograft mice. Tumor tissue sections were stained for SHH (sonic hedgehog) and its effector (Gli-1), cygb/STAP (stellate cell selective markers) α-SMA (PSC activation), F4/80 (macrophage) for imunohistochemistry/immunofluorescence and microRNAs through in situ hybridization. Results: MNP-CUR alone or in combination with GEM inhibits pluripotency maintaining factors (Nanog, Sox-2, c-Myc and Oct-4) in human pancreatic cancer stem cells thereby, restricts the formation of secondary mamospheres. Further investigations reveal that MNP-CUR inhibits Panca proliferation, migration, invasion and tumor growth in xenograft mouse model by suppression of the sonic hedgehog (SHH) signaling pathway and CXCR4/CXCL12 signaling axis that inhibit bidirectional tumor-stromal cells interaction. MNP-CUR treatment alone or in combination with CXCR4 antagonist (amd3100) inhibits CXCL12 induced up regulation of CXCR4, SHH and NFĸB-65 in cells. Further, qRT-PCR results showed that MNP-CUR treatment increases GEM sensitivity by up regulating the human nucleoside transporter genes (hENT, hCNT) and blocking ribonucletide reductase subunits (RRM1/RRM2) which further supports the use of MNP-CUR for suppression of PanCa growth. Immunostaining of tumor sections from treated pancreatic xenograft mice revealed that MNP-CUR treatment efficiently inhibits key proteins of SHH signaling such as SHH and Gli-1. MNP-CUR also disrupts the stroma of fibrotic pancreatic tumors by inhibiting proliferating stellate and myeloid cells. This was indicated by the decreased staining of αSMA, macrophages and cygb/STAP in tumor tissues. Additionally, the tumor tissues from MNP-CUR treated mice showed extensive downregulation of oncogenic miR-21 expression which has been associated with cancer progression and drug resistance. Conclusion: These data suggest that MNP-CUR possesses great promise as a treatment of choice for PanCa. Citation Format: Sheema Khan, Murali M. Yallapu, Sonam Kumari, Aditya Ganju, Swathi Balakrishna, Stephen W. Behrman, Nadeem Zafar, Meena Jaggi, Subhash C. Chauhan. Attenuation of pancreatic cancer stemness and growth by a novel magnetic nanoparticle formulation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3676. doi:10.1158/1538-7445.AM2015-3676

Combination of granulocyte colony-stimulating factor and CXCR4 antagonist AMD3100 for effective harvest of endothelial progenitor cells from peripheral blood and in vitro formation of primitive endothelial networks.

Endothelial progenitor cells (EPC) derived from the circulation may be used to enhance neovascularization. Since the combination of granulocyte colony-stimulating factor (GCSF) and CXCR4 antagonist AMD3100 efficiently mobilizes hematopoietic stem cells into peripheral circulation, it may increase the pool of endogenously circulating EPC. We tested this hypothesis by administering GCSF and AMD3100 to adult rabbits and rats, isolating mononuclear cells from peripheral blood by Ficoll density gradient centrifugation, and characterizing the blood-derived EPC based on morphology, immunophenotyping, gene expression and other functional analyses. These EPC showed clonal growth similar to that of human umbilical vein endothelial cells when cultured in complete EGM-2 medium on collagen I-precoated culture plates. The EPC exhibited a typical cobblestone-like morphology and were relatively homogeneous by the third passage. The cells expressed the typical endothelial marker CD31 based on flow cytometry and fluorescence microscopy, formed capillary-like structures when cultured in Matrigel, internalized DiI-acetylated low-density lipoprotein, bound Ulex europaeus agglutinin-1, and expressed CD31 and several other endothelial markers (VEGFR2, VE-cadherin, Tie-2, eNOS, vWF) at significantly higher levels than bone marrow-derived mesenchymal stem cells. These results suggest that the combination of GCSF and AMD3100 can efficiently release stem cells into peripheral circulation and generate EPC that show the desired morphological, immunophenotypic and functional characteristics. This minimally invasive approach may be useful for autologous cell transplantation for postnatal neovasculogenesis and tissue repair.

Pre-treatment of allogeneic bone marrow recipients with the CXCR4 antagonist AMD3100 transiently enhances hematopoietic chimerism without promoting donor-specific skin allograft tolerance

Hematopoietic chimerism established by allogeneic bone marrow transplantation is known to promote donor-specific organ allograft tolerance; however, clinical application is limited by the need for toxic host conditioning and “megadoses” of donor bone marrow cells. A potential solution to this problem has been suggested by the observation that recipient bone marrow mobilization by the CXCR4 antagonist AMD3100 promotes chimerism in congenic bone marrow transplantation experiments in mice. Here we report that a single subcutaneous dose of 10mg/kg AMD3100 in recipient C57BL/6 mice was able to enhance hematopoietic chimerism when complete MHC-mismatched BALB/c donor bone marrow cells were transplanted 1h after drug dosing. However, levels of chimerism measured 30days post-transplantation were not sustained when mice were reexamined on day 90 post-transplantation. Moreover, transient chimerism induced by this protocol did not support robust donor-specific skin allograft tolerance. Using the same transient immunosuppression protocol, we confirmed that “megadoses” of donor bone marrow cells could induce durable chimerism associated with donor-specific skin allograft tolerance without AMD3100 pre-treatment. We conclude that in this protocol AMD3100 pretreatment may empty bone marrow niches that become reoccupied by allogeneic donor hematopoietic progenitor cells but not by true long-lived donor hematopoietic stem cells, resulting in short-lived chimerism and failure to support durable donor-specific allograft tolerance.

SEMA3F prevents metastasis of colorectal cancer by PI3K-AKT-dependent down-regulation of the ASCL2-CXCR4 axis.

Semaphorin-3F (SEMA3F), an axonal repulsant in nerve development, has been shown to inhibit the progression of human colorectal cancer (CRC); however, the underlying mechanism remains elusive. In this study we found a negative correlation between the levels of SEMA3F and CXCR4 in CRC specimens from 85 patients, confirmed by bioinformatics analysis of gene expression in 229 CRC samples from the Cancer Genome Atlas. SEMA3F(high) /CXCR4(low) patients showed the lowest frequency of lymph node and distant metastasis and the longest survival. Mechanistically, SEMA3F inhibited the invasion and metastasis of CRC cells through PI3K-AKT-dependent down-regulation of the ASCL2-CXCR4 axis. Specifically, ASCL2 enhanced the invasion and metastasis of CRC cells in vitro and expression of ASCL2 correlated with distant metastasis, tumour size and poor overall survival in CRC patients. Treatment of CRC cells with the CXCR4 antagonist AMD3100 attenuated SEMA3F knockdown-induced invasion and metastasis of CRC cells in vitro and in vivo. Our study thus demonstrates that SEMA3F functions as a suppressor of CRC metastasis via down-regulating the ASCL2-CXCR4 axis.

Autophagy is required for stem cell mobilization by G-CSF

AbstractGranulocyte colony-stimulating factor (G-CSF) is widely used clinically to prevent neutropenia after cytotoxic chemotherapy and to mobilize hematopoietic stem cells (HSCs) for transplantation. Autophagy, a process of cytoplasmic component recycling, maintains cellular homeostasis and protects the cell during periods of metabolic stress or nutrient deprivation. We have observed that G-CSF activates autophagy in neutrophils and HSCs from both mouse and human donors. Furthermore, G-CSF–induced neutrophil and HSC mobilization is impaired in the absence of autophagy. In contrast, autophagy is dispensable for direct HSC mobilization in response to the CXCR4 antagonist AMD3100. Altogether, these data demonstrate an important role for G-CSF in invoking autophagy within hematopoietic and myeloid cells and suggest that this pathway is critical for ensuring cell survival in response to clinically relevant cytokine-induced stress. These findings have direct relevance to HSC transplantation and the increasing clinical use of agents that modulate autophagy.

49. In Vivo Gene Therapy of Mobilized Hematopoietic Stem Cells With AD5/35 Vectors Encoding a Sleeping Beauty Transposase Integration Machinery

Current protocols for hematopoietic stem cell (HSC) gene therapy involve the collection of HSCs from donors/patients, in vitro culture, transduction with retrovirus vectors, and retransplantation into myelo-conditioned patients. Besides its technical complexity, disadvantages of this approach include the necessity for culture in the presence of multiple cytokines which can affect the pluripotency of HSCs and their engraftment potential. Furthermore, the requirement for myeloablative regimens in patients with non-malignant disorders creates additional risks. We therefore explored the potential for in vivo transduction and genome editing of HSCs. Previously, we and others reported that human HSCs express high levels of CD46, a complement regulatory protein, and can therefore be efficiently transduced by CD46-targeting adenovirus vectors such as Ad5/35 vectors.In a CD46-transgenic mouse model we showed that HSCs could be flushed from the bone marrow using a mobilizing regimen of GCSF and the CXCR4 antagonist AMD3100. These mobilized HSCs could then be transduced with intravenously injected, GFP-encoding Ad5/35 vectors. Upon transduction, mobilized HSCs relocalized back to the bone marrow, expressed the transgene and were clonogenically active in colony forming unit assays. When we followed transgene expressing HSCs in vivo over a course of 2 weeks we saw a loss of transgene expression over time. This is most likely due to leaky viral gene expression of the first generation Ad vector used in these studies. To avoid these cytotoxic effects, we employed a Helper-dependent Ad (HDAd) vector that is devoid of all viral genes. We compared the transduction performance of the HDAd to the first generation vector both in the CD46-transgenic mouse model as well as in a humanized NOG mouse model.Adenoviral vectors do not integrate into the genome of the host cell and we have therefore only been able to follow transduced cells for limited periods of time. In order to be able to track transduced HSCs and their progeny for extended periods of time and to assess their long-term repopulating potential we are developing a set of HDAd vectors that allow for genomic integration of the transgene using a sleeping beauty transposon approach. In in vitro transduction studies we were able to show that the HDAd-encoded integration machinery can be used to insert a GFP cassette into the genome of HSCs, that the transduced HSCs remain clonogenic and that the transgene is passed on to progeny cells. Preliminary in vivo transduction studies in mobilized CD46-tg mice show GFP expression in up to 2.5% of bone marrow-derived lineage-depleted cells at 4 weeks after vector injection, indicating stable in vivo transduction of HSCs.

Cancer-associated fibroblast-derived CXCL12 causes tumor progression in adenocarcinoma of the esophagogastric junction.

Although cancer-associated fibroblasts (CAFs) mainly produce CXCL12 and stimulate CXCL12/CXCR4 signaling in cancer cells, the significance of this interaction in adenocarcinoma of the esophagogastric junction (AEG) was unclear. This study investigated the functional characteristics of CAF-derived CXCL12 in AEG. Immunohistochemical staining for CXCL12 was performed on sections from 123 AEG patients and analyzed against clinicopathological data. Newly isolated CAFs and normal fibroblasts were examined for phenotype. An invasion assay was performed with AEG cells co-cultured with CAFs isolated from AEG. CXCL12 expression was significantly associated with age, depth of invasion, lymphatic invasion, and lymph node metastases. High CXCL12 expression significantly correlated with poor prognosis. Isolated CAFs had abundant α-smooth muscle actin expression and showed various CXCL12 expression patterns. Notably, AEG cells co-cultured with CXCL(high)-expressing CAFs invaded more than when co-cultured with CXCL(low)-expressing CAFs; these invasive properties were impeded by CXCR4 antagonist AMD3100. We demonstrated that AEG cells co-cultured with CXCL12(high) CAFs were significantly more invasive than those co-cultured with CXCL12(low) CAFs and that high CXCL12 expression correlates with poor prognosis in AEG patients. CXCL12 derived from CAFs in tumor microenvironment stimulates CXCL12/CXCR4 signaling in AEG cells and promotes their invasive ability, resulting in tumor progression.

CXCR4 antagonist AMD3100 redistributes leukocytes from primary immune organs to secondary immune organs, lung, and blood in mice.

AMD3100 (plerixafor), is a specific CXCR4 antagonist approved by the FDA for mobilizing hematopoietic stem cells from bone marrow to blood for transplantation in cancer. AMD3100 also mobilizes most mature leukocyte subsets to blood; however, their source and trafficking potential have not been fully delineated. Here, we show that a single injection of AMD3100 10 mg/kg into C57Bl/6 mice rapidly mobilizes (peak ∼ 2.5 h) the same leukocyte subsets to blood as in humans. Using this model, we found that AMD3100 mobilization of neutrophils, lymphocytes, and monocytes to blood is not reduced by splenectomy or by blockade of lymphocyte egress from lymph node with FTY720, but is coupled to (i) reduced content of each of these cell types in the bone marrow; (ii) reduced T-cell numbers in thymuses; (iii) increased lymphocytes in lymph nodes; and (iv) increased neutrophil and monocyte content in the lung. Direct intrathymic labeling showed that AMD3100 selectively mobilizes naïve thymic CD4(+) and CD8(+) T cells to blood. Finally, AMD3100-induced neutrophil mobilization to blood did not reduce neutrophil trafficking to thioglycollate-inflamed peritoneum. Thus, AMD3100 redistributes lymphocytes, monocytes, and neutrophils from primary immune organs to secondary immune organs, peripheral tissues, and blood, without compromising neutrophil trafficking to inflamed sites.

MB-23 * CO-INHIBITION OF THE SONIC HEDGEHOG AND CXCR4 PATHWAYS UNIQUELY BLOCKS TUMOR INITIATING CELL FUNCTION IN MEDULLOBLASTOMA

Medulloblastoma is the most common malignant brain tumor of childhood. Even with current intensive treatments there is significant morbidity and mortality associated with this diagnosis. Recent hope for improved outcome derives from the stratification of medulloblastoma into four molecular subtypes and the promise that subtype-specific targeted therapy will be more efficacious and less toxic. However, even within specific subtypes there can be variable outcomes, suggesting that further subclasification will be required. We previously showed that CXCR4, a G-protein coupled receptor, is differentially expressed in the Sonic hedgehog (Shh) subtype of medulloblastoma and its activation is required for maximal medulloblastoma growth in vitro and in vivo. We investigated the utility of combining inhibition of both the Shh and CXCR4 pathways in a preclinical model of Shh-medulloblastoma. We measured anti-tumor activity and effects on tumor subtransplantation efficiency of single agents and combined treatment with the Shh antagonist GDC-0449 (vismodegib) and the CXCR4 antagonist AMD3100. We found that combined therapy had the greatest anti-tumor effect and that only inhibition of both pathways abrogated tumorigenicity upon subtransplantation. These results indicated that dual-inhibition was affecting the tumor initiating cell (TIC) population. We used flow cytometry to further investigate this possibility and found that dual inhibition resulted in the loss of a subpopulation of cells with high CXCR4 and CD15 surface expression. Concordant with this diminution in the putative TIC population we found decreased expression of the stem cell markers Sox2, Nanog and Oct4 in doubly treated tumors. Decreased expression of these stem cell markers was associated with increased presence of the repressive histone mark H3K27me3 at their promoters. Together these data indicate that the Shh and CXCR4 signaling pathways in medulloblastoma converge in the subpopulation of TICs to regulate stem cell activity. Dual inhibition may therefore represent a powerful new approach to medulloblastoma cure.

Enhanced SDF-1 and rantes attract the locally injected bone marrow stromal cells to remedy dental biomechanically induced temporomandibular joint osteoarthritic lesions

Enhanced SDF-1 and rantes attract the locally injected bone marrow stromal cells to remedy dental biomechanically induced temporomandibular joint osteoarthritic lesions

Transplanted bone marrow-derived circulating PDGFRα+ cells restore type VII collagen in recessive dystrophic epidermolysis bullosa mouse skin graft.

Recessive dystrophic epidermolysis bullosa (RDEB) is an intractable genetic blistering skin disease in which the epithelial structure easily separates from the underlying dermis because of genetic loss of functional type VII collagen (Col7) in the cutaneous basement membrane zone. Recent studies have demonstrated that allogeneic bone marrow transplantation (BMT) ameliorates the skin blistering phenotype of RDEB patients by restoring Col7. However, the exact therapeutic mechanism of BMT in RDEB remains unclear. In this study, we investigated the roles of transplanted bone marrow-derived circulating mesenchymal cells in RDEB (Col7-null) mice. In wild-type mice with prior GFP-BMT after lethal irradiation, lineage-negative/GFP-positive (Lin(-)/GFP(+)) cells, including platelet-derived growth factor receptor α-positive (PDGFRα(+)) mesenchymal cells, specifically migrated to skin grafts from RDEB mice and expressed Col7. Vascular endothelial cells and follicular keratinocytes in the deep dermis of the skin grafts expressed SDF-1α, and the bone marrow-derived PDGFRα(+) cells expressed CXCR4 on their surface. Systemic administration of the CXCR4 antagonist AMD3100 markedly decreased the migration of bone marrow-derived PDGFRα(+) cells into the skin graft, resulting in persistent epidermal detachment with massive necrosis and inflammation in the skin graft of RDEB mice; without AMD3100 administration, Col7 was significantly supplemented to ameliorate the pathogenic blistering phenotype. Collectively, these data suggest that the SDF1α/CXCR4 signaling axis induces transplanted bone marrow-derived circulating PDGFRα(+) mesenchymal cells to migrate and supply functional Col7 to regenerate RDEB skin.

CXCR4 Antagonist AMD3100 Suppresses the Long-Term Abnormal Structural Changes of Newborn Neurons in the Intraventricular Kainic Acid Model of Epilepsy.

Abnormal hippocampal neurogenesis is a prominent feature of temporal lobe epilepsy (TLE) models, which is thought to contribute to abnormal brain activity. Stromal cell-derived factor-1 (SDF-1) and its specific receptor CXCR4 play important roles in adult neurogenesis. We investigated whether treatment with the CXCR4 antagonist AMD3100 suppressed aberrant hippocampal neurogenesis, as well as the long-term consequences in the intracerebroventricular kainic acid (ICVKA) model of epilepsy. Adult male rats were randomly assigned as control rats, rats subjected to status epilepticus (SE), and post-SE rats treated with AMD3100. Animals in each group were divided into two subgroups (acute stage and chronic stage). We used immunofluorescence staining of BrdU and DCX to analyze the hippocampal neurogenesis on post-SE days 10 or 74. Nissl staining and Timm staining were used to evaluate hippocampal damage and mossy fiber sprouting, respectively. On post-SE day 72, the frequency and mean duration of spontaneous seizures were measured by electroencephalography (EEG). Cognitive function was evaluated by Morris water maze testing on post-SE day 68. The ICVKA model of TLE resulted in aberrant neurogenesis such as altered proliferation, abnormal dendrite development of newborn neurons, as well as spontaneous seizures and spatial learning impairments. More importantly, AMD3100 treatment reversed the aberrant neurogenesis seen after TLE, which was accompanied by decreased long-term seizure activity, though improvement in spatial learning was not seen. AMD3100 could suppress long-term seizure activity and alter adult neurogenesis in the ICVKA model of TLE, which provided morphological evidences that AMD3100 might be beneficial for treating chronic epilepsy.

A critical role of Src family kinase in SDF-1/CXCR4-mediated bone-marrow progenitor cell recruitment to the ischemic heart

The G protein-coupled receptor CXCR4 and its ligand stromal-cell derived factor 1 (SDF-1) play a crucial role in directing progenitor cell (PC) homing to ischemic tissue. The Src family protein kinases (SFK) can be activated by, and serve as effectors of, G proteins. In this study we sought to determine whether SFK play a role in SDF-1/CXCR4-mediated PC homing. First, we investigated whether SDF-1/CXCR4 signaling activates SFK. Bone-marrow mononuclear cells (BM MNCs) were isolated from WT and BM-specific CXCR4-KO mice and treated with SDF-1 and/or CXCR4 antagonist AMD3100. SDF-1 treatment rapidly induced phosphorylation (activation) of hematopoietic Src (i.e., Lyn, Fgr, and Hck) in WT cells but not in AMD3100-treated cells or CXCR4-KO cells. Then, we investigated whether SFK are involved in SDF-1/CXCR4-mediated PC chemotaxis. In a combined chemotaxis and endothelial-progenitor-cell (EPC) colony assay, Src inhibitor SU6656 dose-dependently inhibited the SDF-1-induced migration of colony-forming EPCs. Next, we investigated whether SFK play a role in SDF-1/CXCR4-mediated BM PC homing to the ischemic heart. BM MNCs from CXCR4BAC:eGFP reporter mice were i.v. injected into WT and SDF-1BAC:SDF1-RFP transgenic mice following surgically-induced myocardial infarction (MI). eGFP+ MNCs and eGFP+c-kit+ PCs that were recruited in the infarct border zone in SDF-1BAC:SDF1-RFP recipients were significantly more than that in WT recipients. Treatments of mice with SU6656 significantly reduced eGFP+ and eGFP+c-kit+ cell recruitment in both WT and SDF-1BAC:RFP recipients and abrogated the difference between the two groups. Remarkably, PCs isolated from BM-specific C-terminal Src kinase (CSK)-KO (Src activated) mice were recruited more efficiently than PCs from WT PCs in the WT recipients. In conclusion, SFK are activated by SDF-1/CXCR4 signaling and play an essential role in SDF-1/CXCR4-mediated BM PC chemotactic response and ischemic cardiac recruitment.

ΔNP63α transcriptionally activates chemokine receptor 4 (CXCR4) expression to regulate breast cancer stem cell activity and chemotaxis.

ΔNP63α, the predominant TP63 isoform expressed in diverse epithelial tissues, including the mammary gland, is required for the preservation of stem cells and has been implicated in tumorigenesis and metastasis. Despite data characterizing ΔNP63α as a master regulator of stem cell activity, identification of the targets underlying these effects is incompletely understood. Recently, ΔNP63α was identified as a key regulator in the promotion of proinflammatory programs in squamous cell carcinoma of the head and neck. Inflammation has been implicated as a potent driver of cancer stem cell phenotypes and metastasis. In this study, we sought to identify novel targets of ΔNP63α that confer cancer stem cell and prometastatic properties. Data presented here identify the gene encoding the chemokine receptor 4 (CXCR4) as a transcriptional target of ΔNP63α. Our data indicate that ΔNP63α enhances CXCR4 expression in breast cancer cells via its binding at two regions within the CXCR4 promoter. The CXCR4 antagonist AMD3100 was used to demonstrate that the pro-stem cell activity of ΔNP63α is mediated through its regulation of CXCR4. Importantly, we show that ΔNP63α promotes the chemotaxis of breast cancer cells towards the CXCR4 ligand SDF1α, a process implicated in the trafficking of breast cancer cells to sites of metastasis. This study highlights CXCR4 as a previously unidentified target of ΔNP63α, which plays a significant role in mediating ΔNP63α-dependent stem cell activity and chemotaxis toward SDF1α. Our findings suggest that ΔNP63α regulation of CXCR4 may have strong implications in the regulation of cancer stem cells and metastasis.

Abstract B13: Hypoxia-induced chemokine activation and lymphnode metastases in primary cervix xenografts

Abstract Aim: To examine the role of the chemokine pathway in cervix cancer in the regulation of hypoxia-induced metastases and bone marrow derived myeloid cells (BMDCs) in the tumor microenvironment. Methods: Cervix cancer biopsies from patients in clinical studies at PMH were used for implantation into the cervix of NRG mice. Relative CXCR4 expression by qRT-PCR in biopsies from 117 patients with cervical cancer and 17 primary, orthotopic, cervical cancer xenografts was conducted. Mice bearing orthotopic xenografts were exposed to cyclic hypoxia (12x 10min cycles of breathing 7%O2 or air; 4hr/day for 2 wks) during their growth in combination with AMD3100 (Plerixafor), administered by osmotic pumps (5mg/kg/day) implanted subcutaneously for 3 weeks. Primary tumor size and para-aortic lymph node metastases were assessedfor metastases (H&E staining). Mice received 15x30Gy (2Gy daily 5x/wk) targeted radiotherapy with cisplatin (4mg/kg/wk)(RTCTx) with or without AMD3100. The mice were monitored weekly for tumor growth by CT scanning. Immunohistochemistry was used to analyse levels of hypoxia (EF5/CA-9), blood (CD31) and lymphatic (LYVE-1) vessels, and CXCR4/CXCL12 in the orthotopic tumors and involved lymphnodes. Cd11b staining was used to assess neutrophil infiltration into the tumors. The GI toxicity of AMD3100 with RTCTx was assessed by gut crypt assay. Results: The (early passage) primary orthotopic cervical xenografts used in this study invade and metastasize to lymph nodes in a manner similar to cervical cancer in patients. The microenvironmental features (vascularity, stroma content, hypoxia, IFP) of the xenografts match the original biopsy. The variability in baseline CXCR4 gene expression (by qRT-PCR) in our xenograft models is also similar to that seen in the patient biopsies. Preliminary data also shows comparable CXCL12 and CD11b+ BMDC infiltration in a patient biopsy and in primary xenografts. Induction of tumor hypoxia by exposing the animals to a low oxygen environment increased CXCL12 and CXCR4 gene and protein expression and resulted in a significant increase in the number of lymph node metastases. Treatment with the CXCR4 antagonist AMD3100 reversed these effects. Tumor-bearing animals treated with targeted RTCTx combined with AMD3100 demonstrated significantly enhanced growth delay compared to RTCTx alone and demonstrated reduced metastases at the end of the study. There was no evidence that AMD3100 enhanced the gut toxicity of the RTCTx treatment. Conclusions: Our results suggest that CXCR4 plays an important role in metastasis and tumor growth, under hypoxic conditions, in human cervical cancer. Targeting the CXCR4-CXCL12 axis, with chemokine specific inhibitors,may serve as a novel and attractive therapeutic approach in cervix cancer.These studies provide a strong focus on developing and optimizing new targeted therapeutic approaches aimed at mitigating the adverse consequences of altered chemokine/BMDC signaling and translating these to high-impact phase I/II clinical trials. Citation Format: Naz Chaudary, Salomeh Jelveh, Patricia Lindsay, Melania Pintilie, Michael Milosevic, Richard P. Hill. Hypoxia-induced chemokine activation and lymphnode metastases in primary cervix xenografts. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B13. doi:10.1158/1538-7445.CHTME14-B13

Paracrine SDF-1α signaling mediates the effects of PSCs on GEM chemoresistance through an IL-6 autocrine loop in pancreatic cancer cells

Pancreatic cancer exhibits the poorest prognosis among all tumors and is characterized by high resistance to the currently available chemotherapeutic agents. Our previous studies have suggested that stromal components could promote the chemoresistance of pancreatic cancer cells (PCCs). Here, we explored the roles of pancreatic stellate cells (PSCs) and the SDF-1α/CXCR4 axis in pancreatic cancer chemoresitance. Our results showed that primary PSCs typically expressed SDF-1α, whereas its receptor CXCR4 was highly expressed in PCCs. PSC-conditioned medium (PSC-CM) inhibited Gemcitabine (GEM)-induced cytotoxicity and apoptosis in the human PCC line Panc-1, which was antagonized by an SDF-1α neutralizing Ab. Recombinant human SDF-1α (rhSDF-1α) increased IL-6 expression and secretion in Panc-1 cells in a time and dose-dependent manner, and this effect was suppressed by the CXCR4 antagonist AMD3100. rhSDF-1α protected Panc-1 cells from GEM-induced apoptosis, and the protective effect was significantly reduced by blocking IL-6 using a neutralizing antibody. Moreover, rhSDF-1α increased FAK, ERK1/2, AKT and P38 phosphorylation in Panc-1 cells, and either FAK or ERK1/2 inhibition suppressed SDF-1α-upregulated IL-6 expression. SDF-1α-induced AKT activation was almost completely blocked by FAK inhibition. In conclusion, we demonstrate for the first time that PSCs promote the chemoresistance of PCCs to GEM, and this effect is mediated by paracrine SDF-1α/CXCR4 signaling-induced activation of the intracellular FAK-AKT and ERK1/2 signaling pathways and a subsequent IL-6 autocrine loop in PCCs. Our findings indicate that blocking the PSC-PCC interaction by inhibiting SDF-1α/CXCR4 signaling may be a promising therapeutic strategy for overcoming chemoresistance in pancreatic cancer.