Molecular Pathways: Targeting the CXCR4–CXCL12 Axis—Untapped Potential in the Tumor Microenvironment

Meeting the Challenge of Targeting Cancer Stem Cells

Notwithstanding cancer patients benefit from a plethora of therapeutic alternatives, drug resistance remains a critical hurdle. Indeed, the high mortality rate is associated with metastatic disease, which is mostly incurable due to the refractoriness of metastatic cells to current treatments. Increasing data demonstrate that tumors contain a small subpopulation of cancer stem cells (CSCs) able to establish primary tumor and metastasis. CSCs are endowed with multiple treatment resistance capabilities comprising a highly efficient DNA damage repair machinery, the activation of survival pathways, enhanced cellular plasticity, immune evasion and the adaptation to a hostile microenvironment. Due to the presence of distinct cell populations within a tumor, cancer research has to face the major challenge of targeting the intra-tumoral as well as inter-tumoral heterogeneity. Thus, targeting molecular drivers operating in CSCs, in combination with standard treatments, may improve cancer patients’ outcomes, yielding long-lasting responses. Here, we report a comprehensive overview on the most significant therapeutic advances that have changed the known paradigms of cancer treatment with a particular emphasis on newly developed compounds that selectively affect the CSC population. Specifically, we are focusing on innovative therapeutic approaches including differentiation therapy, anti-angiogenic compounds, immunotherapy and inhibition of epigenetic enzymes and microenvironmental cues.

Comprehensive Genomic Profiling Reveals Diverse but Actionable Molecular Portfolios across Hematologic Malignancies: Implications for Next Generation Clinical Trials

Background: The translation of genomic discoveries to the clinic is the cornerstone of precision medicine. However, incorporating next generation sequencing (NGS) of hematologic malignancies into clinical management remains limited. Methods: We describe 235 patients who underwent integrated NGS profiling (406 genes) and analyze the alterations and their potential actionability. Results: Overall, 227 patients (96.5%) had adequate tissue. Most common diagnoses included myelodysplastic syndrome (22.9%), chronic lymphocytic leukemia (17.2%), non-Hodgkin lymphoma (13.2%), acute myeloid leukemia (11%), myeloproliferative neoplasm (9.2%), acute lymphoblastic leukemia (8.8%), and multiple myeloma (7.5%). Most patients (N = 197/227 (87%)) harbored ≥1 genomic alteration(s); 170/227 (75%), ≥1 potentially actionable alteration(s) targetable by an FDA-approved (mostly off-label) or an investigational agent. Altogether, 546 distinct alterations were seen, most commonly involving TP53 (10.8%), TET2 (4.6%), and DNMT3A (4.2%). The median tumor mutational burden (TMB) was low (1.7 alterations/megabase); 12% of patients had intermediate or high TMB (higher TMB correlates with favorable response to anti-PD1/PDL1 inhibition in solid tumors). In conclusion, 96.5% of patients with hematologic malignancies have adequate tissue for comprehensive genomic profiling. Most patients had unique molecular signatures, and 75% had alterations that may be pharmacologically tractable with gene- or immune-targeted agents.

Adaptive Immunodeficiency in WHIM Syndrome

Cysteine-X-cysteine chemokine receptor 4 (CXCR4) is a broadly expressed and multifunctional G protein-coupled chemokine receptor critical for organogenesis, hematopoiesis, and antimicrobial host defense. In the hematopoietic system, the binding of CXCR4 to its cognate chemokine ligand, CXCL12, mediates leukocyte trafficking, distribution, survival, activation, and proliferation. Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare, autosomal dominant, combined immunodeficiency disorder caused by mutations in the C-terminus of CXCR4 that prevent receptor downregulation and therefore result in pathologically increased signaling. The “M” in the acronym WHIM refers to myelokathexis, the retention of neutrophils in the bone marrow resulting in neutropenia, which explains in part the increased susceptibility to bacterial infection. However, WHIM patients also present with B and T lymphopenia, which may explain the susceptibility to human papillomavirus (HPV), the cause of warts. The impact of WHIM mutations on lymphocytes and adaptive immunity has received less attention than myelokathexis and is the focus of this review.

PD-L1 microSPECT/CT Imaging for Longitudinal Monitoring of PD-L1 Expression in Syngeneic and Humanized Mouse Models for Cancer

Antibodies that block the interaction between programmed death ligand 1 (PD-L1) and PD-1 have shown impressive responses in subgroups of patients with cancer. PD-L1 expression in tumors seems to be a prerequisite for treatment response. However, PD-L1 is heterogeneously expressed within tumor lesions and may change upon disease progression and treatment. Imaging of PD-L1 could aid in patient selection. Previously, we showed the feasibility to image PD-L1⁺ tumors in immunodeficient mice. However, PD-L1 is also expressed on immune cell subsets. Therefore, the aim of this study was to assess the potential of PD-L1 micro single-photon emission tomography/computed tomography (microSPECT/CT) using radiolabeled PD-L1 antibodies to (i) measure PD-L1 expression in two immunocompetent tumor models (syngeneic mice and humanized mice harboring PD-L1 expressing immune cells) and (ii) monitor therapy-induced changes in tumor PD-L1 expression. We showed that radiolabeled PD-L1 antibodies accumulated preferentially in PD-L1⁺ tumors, despite considerable uptake in certain normal lymphoid tissues (spleen and lymph nodes) and nonlymphoid tissues (duodenum and brown fat). PD-L1 microSPECT/CT imaging could also distinguish between high and low PD-L1-expressing tumors. The presence of PD-L1⁺ immune cells did not compromise tumor uptake of the human PD-L1 antibodies in humanized mice, and we demonstrated that radiotherapy-induced upregulation of PD-L1 expression in murine tumors could be monitored with microSPECT/CT imaging. Together, these data demonstrate that PD-L1 microSPECT/CT is a sensitive technique to detect variations in tumor PD-L1 expression, and in the future, this technique may enable patient selection for PD-1/PD-L1-targeted therapy.

Roles of SDF-1/CXCR4 axis in cartilage endplate stem cells mediated promotion of nucleus pulposus cells proliferation

Stem cells transplantation has shown considerable promise in intervertebral disc repair and low-back pain release. Cartilage endplate stem cells (CESCs) also showed potential for nucleus pulposus (NP) regeneration in a rabbit disc degeneration model, the precise mechanism was unclear. Here we investigated the effects of CESCs on NP cells (NPCs) proliferation and the mechanism in vitro. CESCs and NPCs were isolated from surgical specimens of degenerative human lumbar disc. NPCs were co-cultured with CESCs at a 1:1 ratio or cultured in CESCs conditioned medium (CESCs-CM). NPCs proliferation was evaluated by Ki-67 staining, CCK-8 assay and cell cycle analysis. Gene expressions were detected by qRT-PCR and activation of Akt and ERK1/2 was detected by western blot. CXCR4 antagonist AMD3100 was used to block SDF-1/CXCR4 axis. ERK1/2 and Akt inhibitors were used to block Akt and ERK1/2 activation. Results showed that NPCs proliferation was promoted by direct-contact co-culturing with CESCs as well as culturing in CESCs-CM. SDF-1 expression level in CESCs was significantly higher than that in NPCs, while CXCR4 was the opposite. Promotion of NPCs proliferation mediated by CESCs-CM could be partially attenuated by AMD3100. CESCs-CM activated both Akt and ERK1/2 in NPCs, while rhSDF-1 scarcely activated Akt but obviously activated ERK1/2. Akt and ERK1/2 inhibitors could partially inhibited CESCs-CM mediated promotion of NPCs proliferation and showed cumulative effect, while ERK1/2 inhibitor and AMD3100 could significantly abrogate SDF-1 mediated promotion of NPCs proliferation. Our results suggested that CESCs might promote NPCs proliferation in a paracrine pathway, which was partially mediated by SDF-1/CXCR4 axis via ERK1/2 signaling transduction pathway.

CXCR4-directed theranostics in oncology and inflammation

Given its prominent role in inflammation and cancer biology, the C-X-C motif chemokine receptor 4 (CXCR4) has gained a lot of attention in the recent years. This review gives a short overview of the physiology and pathology of chemokines and chemokine receptors and then focuses on the current experience of targeting CXCR4, using radiolabeled receptor ligands suitable for positron emission tomography (PET) imaging, in both hematologic and solid malignancy as well as in inflammatory conditions. Additionally, CXCR4-directed endoradiotherapy (ERT) as a new treatment option is discussed.

CXCR4 Based Therapeutics for Non-Small Cell Lung Cancer (NSCLC)

Lung cancer is the second most common malignancy. Unfortunately, despite advances in multimodality therapeutics for the disease, the overall five-year survival rate among newly diagnosed lung cancer patients remains in the range region of 15%. In addition, although immune checkpoint inhibitors are increasingly being incorporated into lung cancer treatment protocols, the proportion of patients that respond to these agents remains low and the duration of response is often short. Therefore, novel methodologies to enhance the efficacy of immunotherapy in lung cancer are highly desirable. Chemokines are small chemotactic cytokines that interact with their 7 transmembrane G-protein⁻coupled receptors, to guide immune cell trafficking in the body under both physiologic and pathologic conditions. Tumor cells highjack a small repertoire of the chemokine/chemokine receptor system and utilize it in a manner that benefits local tumor growth and distant spread. The chemokine receptor, CXCR4 is expressed in over 30 types of malignant tumors and, through interaction with its ligand CXCL12, was shown exert pleotropic pro-tumorigenic effects. In this review, the pathologic roles that CXCL12/CXCR4 play in lung cancer propagation are presented. Furthermore, the challenges and potential benefits of incorporating drugs that target CXCL12/CXCR4 into immune-based lung cancer therapeutic protocols are discussed.

Partial agonist activity of α1-adrenergic receptor antagonists for chemokine (C-X-C motif) receptor 4 and atypical chemokine receptor 3

We observed in PRESTO-Tango β-arrestin recruitment assays that the α₁-adrenergic receptor (AR) antagonist prazosin activates chemokine (C-X-C motif) receptor (CXCR)4. This prompted us to further examine this unexpected pharmacological behavior. We screened a panel of 14 α_1/2- and β_1/2/3-AR antagonists for CXCR4 and atypical chemokine receptor (ACKR)3 agonist activity in PRESTO-Tango assays against the cognate agonist CXCL12. We observed that multiple α₁-AR antagonists activate CXCR4 (CXCL12 = prazosin = cyclazosin > doxazosin) and ACKR3 (CXCL12 = prazosin = cyclazosin > alfuzosin = doxazosin = phentolamine > terazosin = silodosin = tamsulosin). The two strongest CXCR4/ACKR3 activators, prazosin and cyclazosin, were selected for a more detailed evaluation. We found that the drugs dose-dependently activate both receptors in β-arrestin recruitment assays, stimulate ERK1/2 phosphorylation in HEK293 cells overexpressing each receptor, and that their effects on CXCR4 could be inhibited with AMD3100. Both α₁-AR antagonists induced significant chemical shift changes in the ¹H-¹³C-heteronuclear single quantum correlation spectrum of CXCR4 and ACKR3 in membranes, suggesting receptor binding. Furthermore, prazosin and cyclazosin induced internalization of endogenous CXCR4/ACKR3 in human vascular smooth muscle cells (hVSMC). While these drugs did not in induce chemotaxis in hVSMC, they inhibited CXCL12-induced chemotaxis with high efficacy and potency (IC₅₀: prazosin—4.5 nM, cyclazosin 11.6 pM). Our findings reveal unexpected pharmacological properties of prazosin, cyclazosin, and likely other α₁-AR antagonists. The results of the present study imply that prazosin and cyclazosin are biased or partial CXCR4/ACKR3 agonists, which function as potent CXCL12 antagonists. Our findings could provide a mechanistic basis for previously observed anti-cancer properties of α₁-AR antagonists and support the concept that prazosin could be re-purposed for the treatment of disease processes in which CXCR4 and ACKR3 are thought to play significant pathophysiological roles, such as cancer metastases or various autoimmune pathologies.

CARMA3 Is a Critical Mediator of G Protein-Coupled Receptor and Receptor Tyrosine Kinase-Driven Solid Tumor Pathogenesis

The CARMA–Bcl10–MALT1 (CBM) signalosome is an intracellular protein complex composed of a CARMA scaffolding protein, the Bcl10 linker protein, and the MALT1 protease. This complex was first recognized because the genes encoding its components are targeted by mutation and chromosomal translocation in lymphoid malignancy. We now know that the CBM signalosome plays a critical role in normal lymphocyte function by mediating antigen receptor-dependent activation of the pro-inflammatory, pro-survival NF-κB transcription factor, and that deregulation of this signaling complex promotes B-cell lymphomagenesis. More recently, we and others have demonstrated that a CBM signalosome also operates in cells outside of the immune system, including in several solid tumors. While CARMA1 (also referred to as CARD11) is expressed primarily within lymphoid tissues, the related scaffolding protein, CARMA3 (CARD10), is more widely expressed and participates in a CARMA3-containing CBM complex in a variety of cell types. The CARMA3-containing CBM complex operates downstream of specific G protein-coupled receptors (GPCRs) and/or growth factor receptor tyrosine kinases (RTKs). Since inappropriate expression and activation of GPCRs and/or RTKs underlies the pathogenesis of several solid tumors, there is now great interest in elucidating the contribution of CARMA3-mediated cellular signaling in these malignancies. Here, we summarize the key discoveries leading to our current understanding of the role of CARMA3 in solid tumor biology and highlight the current gaps in our knowledge.

Cancer Cells Exploit Notch Signaling to Redefine a Supportive Cytokine Milieu

Notch signaling is a well-known key player in the communication between adjacent cells during organ development, when it controls several processes involved in cell differentiation. Notch-mediated communication may occur through the interaction of Notch receptors with ligands on adjacent cells or by a paracrine/endocrine fashion, through soluble molecules that can mediate the communication between cells at distant sites. Dysregulation of Notch pathway causes a number of disorders, including cancer. Notch hyperactivation may be caused by mutations of Notch-related genes, dysregulated upstream pathways, or microenvironment signals. Cancer cells may exploit this aberrant signaling to "educate" the surrounding microenvironment cells toward a pro-tumoral behavior. This may occur because of key cytokines secreted by tumor cells or it may involve the microenvironment through the activation of Notch signaling in stromal cells, an event mediated by a direct cell-to-cell contact and resulting in the increased secretion of several pro-tumorigenic cytokines. Up to now, review articles were mainly focused on Notch contribution in a specific tumor context or immune cell populations. Here, we provide a comprehensive overview on the outcomes of Notch-mediated pathological interactions in different tumor settings and on the molecular and cellular mediators involved in this process. We describe how Notch dysregulation in cancer may alter the cytokine network and its outcomes on tumor progression and antitumor immune response.

Cellular traffic through afferent lymphatic vessels

The lymphatic system has long been known to serve as a highway for migrating leukocytes from peripheral tissue to draining lymph nodes (dLNs) and back to circulation, thereby contributing to the induction of adaptive immunity and immunesurveillance. Lymphatic vessels (LVs) present in peripheral tissues upstream of a first dLN are generally referred to as afferent LVs. In contrast to migration through blood vessels (BVs), the detailed molecular and cellular requirements of cellular traffic through afferent LVs have only recently started to be unraveled. Progress in our ability to track the migration of lymph-borne cell populations, in combination with cutting-edge imaging technologies, nowadays allows the investigation and visualization of lymphatic migration of endogenous leukocytes, both at the population and at the single-cell level. These studies have revealed that leukocyte trafficking through afferent LVs generally follows a step-wise migration pattern, relying on the active interplay of numerous molecules. In this review, we will summarize and discuss current knowledge of cellular traffic through afferent LVs. We will first outline how the structure of the afferent LV network supports leukocyte migration and highlight important molecules involved in the migration of dendritic cells (DCs), T cells and neutrophils, i.e. the most prominent cell types trafficking through afferent LVs. Additionally, we will describe how tumor cells hijack the lymphatic system for their dissemination to draining LNs. Finally, we will summarize and discuss our current understanding of the functional significance as well as the therapeutic implications of cell traffic through afferent LVs.

A role for the CXCR4-CXCL12 axis in the little skate, Leucoraja erinacea

The interaction between C-X-C chemokine receptor type 4 (CXCR4) and its cognate ligand C-X-C motif chemokine ligand 12 (CXCL12) plays a critical role in regulating hematopoietic stem cell activation and subsequent cellular mobilization. Extensive studies of these genes have been conducted in mammals, but much less is known about the expression and function of CXCR4 and CXCL12 in non-mammalian vertebrates. In the present study, we identify simultaneous expression of CXCR4 and CXCL12 orthologs in the epigonal organ (the primary hematopoietic tissue) of the little skate, Leucoraja erinacea. Genetic and phylogenetic analyses were functionally supported by significant mobilization of leukocytes following administration of Plerixafor, a CXCR4 antagonist and clinically important drug. Our results provide evidence that, as in humans, Plerixafor disrupts CXCR4/CXCL12 binding in the little skate, facilitating release of leukocytes into the bloodstream. Our study illustrates the value of the little skate as a model organism, particularly in studies of hematopoiesis and potentially for preclinical research on hematological and vascular disorders.

Working Toward a Genomic Prognostic Classification of Waldenström Macroglobulinemia: C-X-C Chemokine Receptor Type 4 Mutation and Beyond

Waldenström macroglobulinemia is a rare indolent B-cell lymphoma. Whole-exome sequencing studies have improved our knowledge of the Waldenström macroglobulinemia mutational landscape. The MYD88 L265P mutation is present in nearly 90% of patients with Waldenström macroglobulinemia. CXCR4 mutations are identified in approximately 30% of MYD88L265P cases and have been associated with ibrutinib resistance in clinical trials. Mutations in CD79B, ARID1a, or TP53 were described at lower frequency. Deciphering the earliest initiating lesions and identifying the molecular alterations leading to disease progression currently represent important goals in the future to identify the most relevant targets for precision therapy in Waldenström macroglobulinemia.

Targeting Stemness: Implications for Precision Medicine in Breast Cancer

The genomic landscape of breast cancer has been delineated in recent years. Advances in molecular characterization and targeting strategies are making it feasible to integrate clinical, genome-based and phenotype-based diagnostic and therapeutic methods and apply them to individual patient in the era of precision medicine. Cancer stem cells (CSCs) are a subpopulation in the tumor which have the capability of self-renewal and differentiation. Breast CSCs have important clinical implications as they account for tumor initiation, maintenance, metastasis, therapy resistance, and relapse. In this chapter, we will introduce approaches used to characterize breast CSCs, crucial pathways involved in regulating cancer stemness, and implications of breast CSCs in the precision diagnosis and treatment of breast cancer. We will also discuss novel compounds and therapeutic strategies that selectively target breast CSCs. Integration of breast CSC-related molecular diagnosis and targeted therapy into the clinical workflow of precision medicine has the potential to deliver more effective treatment to breast cancer patients.

Pharmacological modulation of CXCR4 cooperates with BET bromodomain inhibition in diffuse large B-cell lymphoma

Constitutive activation of the chemokine receptor CXCR4 has been associated with tumor progression, invasion, and chemotherapy resistance in different cancer subtypes. Although the CXCR4 pathway has recently been suggested as an adverse prognostic marker in diffuse large B-cell lymphoma, its biological relevance in this disease remains underexplored. In a homogeneous set of 52 biopsies from patients, an antibody-based cytokine array showed that tissue levels of CXCL12 correlated with high microvessel density and bone marrow involvement at diagnosis, supporting a role for the CXCL12-CXCR4 axis in disease progression. We then identified the tetra-amine IQS-01.01RS as a potent inverse agonist of the receptor, preventing CXCL12-mediated chemotaxis and triggering apoptosis in a panel of 18 cell lines and primary cultures, with superior mobilizing properties in vivo than those of the standard agent. IQS-01.01RS activity was associated with downregulation of p-AKT, p-ERK1/2 and destabilization of MYC, allowing a synergistic interaction with the bromodomain and extra-terminal domain inhibitor, CPI203. In a xenotransplant model of diffuse large B-cell lymphoma, the combination of IQS-01.01RS and CPI203 decreased tumor burden through MYC and p-AKT downregulation, and enhanced the induction of apoptosis. Thus, our results point out an emerging role of CXCL12-CXCR4 in the pathogenesis of diffuse large B-cell lymphoma and support the simultaneous targeting of CXCR4 and bromodomain proteins as a promising, rationale-based strategy for the treatment of this disease.

Epigenetic Regulation of CXCL12 Plays a Critical Role in Mediating Tumor Progression and the Immune Response In Osteosarcoma

The mechanism by which osteosarcomas metastasize is elusive, and challenges remain regarding its treatment with modalities including immunotherapy. CXCL12 is deeply involved in the process of tumor metastasis and T-cell homing, which is driven by a chemokine gradient, but healthy bones are supposed to preferentially express CXCL12. Here, we show for the first time that osteosarcomas epigenetically downregulate CXCL12 expression via DNA methyltransferase 1 (DNMT1) and consequently acquire the ability to metastasize and to impair cytotoxic T-cell homing to the tumor site. Analysis of human osteosarcoma cases further revealed that CXCL12 expression strongly correlated with overall survival. Evaluations on fresh human chemotherapy-free osteosarcoma samples also showed a positive correlation between CXCL12 concentration and the number of intratumoral lymphocytes. Critically, treatment targeting DNMT1 in immunocompetent mouse models significantly elevated expression of CXCL12 in tumors, resulting in a robust immune response and consequently eradicating early lung metastases in addition to suppressing subcutaneous tumor growth. These antitumor effects were abrogated by CXCL12-CXCR4 blockade or CD8⁺ T-cell depletion. Collectively, our data show that CXCL12 regulation plays a significant role in both tumor progression and immune response, and targeting CXCL12 is promising for therapeutics against osteosarcoma.Significance: Epigenetic regulation of CXCL12 controls metastasis and immune response in osteosarcoma, suggesting epigenetic therapies or therapies targeting CXCL12 have potential for therapeutic intervention in osteosarcoma. Cancer Res; 78(14); 3938-53. ©2018 AACR.

Notch signaling as a therapeutic target for acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Although the therapy of ALL has significantly improved, the heterogeneous genetic landscape of the disease often causes relapse, which is difficult to treat. Achieving a positive outcome for patients with relapsed or refractory ALL remains a challenging issue. The high prevalence of NOTCH-activating mutations in T-cell acute lymphoblastic leukemia (T-ALL) and the central role of NOTCH signaling in regulating cell survival and growth of ALL provide a rationale for the development of Notch signaling-targeted strategies in this disease. Therapeutic alternatives with effective anti-leukemic potential and low toxicity are needed. Areas covered: This review provides an overview of the currently available drugs directly or indirectly targeting Notch signaling in ALL. Besides considering the known Notch targeting approaches, such as γ-secretase inhibitors (GSIs) and Notch inhibiting antibodies (mAbs), currently in clinical trials, we focus on the recent insights into the molecular mechanisms underlying the Notch signaling regulation in ALL. Expert opinion: Novel drugs targeting specific steps of Notch signaling or intersecting pathways could improve the efficiency of the conventional hematological cancers therapies. Further studies are required to translate the new findings into future clinical applications.

AMD3100 Augments the Efficacy of Mesothelin-Targeted, Immune-Activating VIC-008 in Mesothelioma by Modulating Intratumoral Immunosuppression

AMD3100 (plerixafor), a CXCR4 antagonist, has been demonstrated to suppress tumor growth and modulate intratumoral T-cell trafficking. However, the effect of AMD3100 on immunomodulation remains elusive. Here, we explored immunomodulation and antitumor efficacy of AMD3100 in combination with a previously developed mesothelin-targeted, immune-activating fusion protein, VIC-008, in two syngeneic, orthotopic models of malignant mesothelioma in immunocompetent mice. We showed that combination therapy significantly suppressed tumor growth and prolonged animal survival in two mouse models. Tumor control and survival benefit were associated with enhanced antitumor immunity. VIC-008 augmented mesothelin-specific CD8⁺ T-cell responses in the spleen and lymph nodes and facilitated intratumoral lymphocytic infiltration. However, VIC-008 treatment was associated with increased programmed cell death protein-1 (PD-1) expression on intratumoral CD8⁺ T cells, likely due to high CXCL12 in the tumor microenvironment. AMD3100 alone and in combination with VIC-008 modulated immunosuppression in tumors and the immune system through suppression of PD-1 expression on CD8⁺ T cells and conversion of regulatory T cells (T_regs) into CD4⁺CD25^-Foxp3⁺IL2⁺CD40L⁺ helper-like cells. In mechanistic studies, we demonstrated that AMD3100-driven T_reg reprogramming required T cell receptor (TCR) activation and was associated with loss of PTEN due to oxidative inactivation. The combination of VIC-008 augmentation of tumor-specific CD8⁺ T-cell responses with AMD3100 abrogation of immunosuppression conferred significant benefits for tumor control and animal survival. These data provide new mechanistic insight into AMD3100-mediated immunomodulation and highlight the enhanced antitumor effect of AMD3100 in combination with a tumor antigen-targeted therapy in mouse malignant mesothelioma, which could be clinically relevant to patients with this difficult-to-treat disease. Cancer Immunol Res; 6(5); 539-51. ©2018 AACR.

CXCR4/CXCR7/CXCL12-Axis in Follicular Thyroid Carcinoma

Background: Follicular thyroid carcinoma's (FTC) often benign course is partially due to adjuvant radioactive iodine (RAI) treatment. However, once the tumour has spread and fails to retain RAI, the therapeutic options are limited and the outcome is poor. In this subset of patients, the identification of novel druggable biomarkers appears invaluable. Here, we investigated the stage dependent expression and functional role of the C-X-C chemokine receptors type 4 and 7 (CXCR4/7) in FTC.

Methods: CXCR4/7 expression was examined in 44 FTC and corresponding non-neoplastic thyroid specimens as well as 10 FTC distant metastases and 18 follicular adenomas using tissue microarray technology. Expression levels were correlated with clinicopathological variables as well as overall and recurrence free survival. Changes regarding cell cycle activation, tumour cell invasiveness and mRNA expression of genes related to epithelial-mesenchymal transition (EMT) were investigated after treatment with recombinant human SDF1α/CXCL12 (rh-SDF1α) and CXCR4 antagonists AMD3100 and WZ811.

Results: CXCR4/7 expression was associated with large tumour size, advanced UICC stage as well as shorter overall and recurrence free survival. CXCR4 was significantly higher expressed in distant metastases than in primary tumour cores. In addition, rh-SDF1α induced invasive growth, cell cycle activation and EMT, while CXCR4 antagonists significantly reduced FTC invasiveness in vitro.

Conclusion: Here we provide first evidence of the biological importance of the CXCR4/CXCR7/CXCL12 axis in FTC. Our findings underscore the therapeutic potential of this chemokine receptor family in advanced FTC and offer new valuable insight into the oncogenesis of metastatic FTC.

How to Hit Mesenchymal Stromal Cells and Make the Tumor Microenvironment Immunostimulant Rather Than Immunosuppressive

Experimental evidence indicates that mesenchymal stromal cells (MSCs) may regulate tumor microenvironment (TME). It is conceivable that the interaction with MSC can influence neoplastic cell functional behavior, remodeling TME and generating a tumor cell niche that supports tissue neovascularization, tumor invasion and metastasization. In addition, MSC can release transforming growth factor-beta that is involved in the epithelial-mesenchymal transition of carcinoma cells; this transition is essential to give rise to aggressive tumor cells and favor cancer progression. Also, MSC can both affect the anti-tumor immune response and limit drug availability surrounding tumor cells, thus creating a sort of barrier. This mechanism, in principle, should limit tumor expansion but, on the contrary, often leads to the impairment of the immune system-mediated recognition of tumor cells. Furthermore, the cross-talk between MSC and anti-tumor lymphocytes of the innate and adaptive arms of the immune system strongly drives TME to become immunosuppressive. Indeed, MSC can trigger the generation of several types of regulatory cells which block immune response and eventually impair the elimination of tumor cells. Based on these considerations, it should be possible to favor the anti-tumor immune response acting on TME. First, we will review the molecular mechanisms involved in MSC-mediated regulation of immune response. Second, we will focus on the experimental data supporting that it is possible to convert TME from immunosuppressive to immunostimulant, specifically targeting MSC.

CXCL12 promoter methylation and PD-L1 expression as prognostic biomarkers in prostate cancer patients

Background

The CXCR4/CXCL12 axis plays a central role in systemic metastasis of prostate carcinoma (PCa), thereby representing a promising target for future therapies. Recent data suggest that the CXCR4/CXCL12 axis is functionally linked to the PD-1/PD-L1 immune checkpoint. We evaluated the prognostic value of aberrant CXCL12 DNA methylation with respect to PD-L1 expression in primary PCa.

Results

CXCL12 methylation showed a consistent significant correlation with Gleason grading groups in both cohorts (p < 0.001 for training and p = 0.034 for testing cohort). Short BCR-free survival was significantly associated with aberrant CXCL12 methylation in both cohorts and served as an independent prognostic factor in the testing cohort (hazard ratio = 1.92 [95%CI: 1.12–3.27], p = 0.049). Concomitant aberrant CXCL12 methylation and high PD-L1 expression was significantly associated with shorter BCR-free survival (p = 0.005). In comparative analysis, the CXCL12 methylation assay was able to provide approximately equivalent results in biopsy and prostatectomy specimens.

Materials and Methods

CXCL12 methylation was determined by means of a methylation specific quantitative PCR analysis in a radical prostatectomy patient cohort (n = 247, training cohort). Data published by The Cancer Genome Atlas served as a testing cohort (n = 498). CXCL12 methylation results were correlated to clinicopathological parameters including biochemical recurrence (BCR)-free survival.

Conclusions

CXCL12 methylation is a powerful prognostic biomarker for BCR in PCa patients after radical prostatectomy. Further studies need to ascertain if CXCL12 methylation may aid in planning active surveillance strategies.

Breast cancer metastasis to liver and lung is facilitated by Pit-1-CXCL12-CXCR4 axis

Development of human tumors is driven by accumulation of alterations in tumor suppressor genes and oncogenes in cells. The POU1F1 transcription factor (also known Pit-1) is expressed in the mammary gland and its overexpression induces profound phenotypic changes in proteins involved in breast cancer progression. Patients with breast cancer and elevated expression of Pit-1 show a positive correlation with the occurrence of distant metastasis and poor overall survival. However, some mediators of Pit-1 actions are still unknown. Here, we show that CXCR4 chemokine receptor and its ligand CXCL12 play a critical role in the pro-tumoral process induced by Pit-1. We found that Pit-1 increases mRNA and protein in both CXCR4 and CXCL12. Knock-down of CXCR4 reduces tumor growth and spread of Pit-1 overexpressing cells in a zebrafish xenograft model. Furthermore, we described for the first time pro-angiogenic effects of Pit-1 through the CXCL12-CXCR4 axis, and that extravasation of Pit-1 overexpressing breast cancer cells is strongly reduced in CXCL12-deprived target tissues. Finally, in breast cancer patients, expression of Pit-1 in primary tumors was found to be positively correlated with CXCR4 and CXCL12, with specific metastasis in liver and lung, and with clinical outcome. Our results suggest that Pit-1-CXCL12-CXCR4 axis could be involved in chemotaxis guidance during the metastatic process, and may represent prognostic and/or therapeutic targets in breast tumors.

Dual Targeting of Acute Leukemia and Supporting Niche by CXCR4-Directed Theranostics

C-X-C chemokine receptor 4 (CXCR4) is a transmembrane receptor with pivotal roles in cell homing and hematopoiesis. CXCR4 is also involved in survival, proliferation and dissemination of cancer, including acute lymphoblastic and myeloid leukemia (ALL, AML). Relapsed/refractory ALL and AML are frequently resistant to conventional therapy and novel highly active strategies are urgently needed to overcome resistance. Methods: We used patient-derived (PDX) and cell line-based xenograft mouse models of ALL and AML to evaluate the efficacy and toxicity of a CXCR4-targeted endoradiotherapy (ERT) theranostic approach. Results: The positron emission tomography (PET) tracer 68Ga-Pentixafor enabled visualization of CXCR4 positive leukemic burden. In xenografts, CXCR4-directed ERT with 177Lu-Pentixather distributed to leukemia harboring organs and resulted in efficient reduction of leukemia. Despite a substantial in vivo cross-fire effect to the leukemia microenvironment, mesenchymal stem cells (MSCs) subjected to ERT were viable and capable of supporting the growth and differentiation of non-targeted normal hematopoietic cells ex vivo. Finally, three patients with refractory AML after first allogeneic hematopoietic stem cell transplantation (alloSCT) underwent CXCR4-directed ERT resulting in leukemia clearance, second alloSCT, and successful hematopoietic engraftment. Conclusion: Targeting CXCR4 with ERT is feasible and provides a highly efficient means to reduce refractory acute leukemia for subsequent cellular therapies. Prospective clinical trials testing the incorporation of CXCR4 targeting into conditioning regimens for alloSCT are highly warranted.

The good and bad faces of the CXCR4 chemokine receptor

Chemokines are chemotactic cytokines that promote cell migration and activation under homeostatic and inflammatory conditions. Chemokines bind to seven transmembrane-spanning receptors that are coupled to heterotrimeric guanine nucleotide-binding (G) proteins, which are the responsible for intracellularly transmitting the activating signals for cell migration. Hematopoiesis, vascular development, lymphoid organ morphogenesis, cardiogenesis and neural differentiation are amongst the processes involving chemokine function. In addition, immune cell trafficking from bone marrow to blood circulation, and from blood and lymph to lymphoid and inflamed tissues, is tightly regulated by chemokines both under physiological conditions and also in autoimmune diseases. Furthermore, chemokine binding to their receptors stimulate trafficking to and positioning of cancer cells into target tissues and organs during tumour dissemination. The CXCL12 chemokine (also known as stromal-cell derived factor-1α, SDF-1α) plays key roles in hematopoiesis and lymphoid tissue architecture, in cardiogenesis, vascular formation and neurogenesis, as well as in the trafficking of solid and hematological cancer cell types. CXCL12 binds to the CXCR4 receptor, a multi-facetted molecule which tightly mirrors CXCL12 functions in homeostasis and disease. This review addresses the important roles of the CXCR4-CXCL12 axis in homeostasis, specially focusing in hematopoiesis, as well as it provides a picture of CXCR4 as mediator of cancer cell spreading, and a view of the available CXCR4 antagonists in different cancer types.

CXCR4/CXCR7/CXCL12 axis promotes an invasive phenotype in medullary thyroid carcinoma

Background:

Medullary thyroid carcinoma (MTC) is a rare and challenging endocrine malignancy. Once spread, the therapeutic options are limited and the outcome poor. For these patients, the identification of new druggable biological markers is of great importance. Here, we investigated the prognostic and biological role of the C-X-C chemokine receptors type 4 and 7 (CXCR4/7) in MTC.

Methods:

Eighty-six MTC and corresponding non-neoplastic thyroid specimens were immunohistochemically stained for CXCR4/7 using tissue microarray technology and expression levels correlated with clinicopathological variables. Medullary thyroid carcinoma cell line TT was treated with recombinant human SDF1α/CXCL12 (rh-SDF1α) and CXCR4 antagonists AMD3100 and WZ811. Changes in cell cycle activation, tumour cell invasiveness as well as changes in mRNA expression levels of genes associated with epithelial–mesenchymal transition (EMT) were investigated.

Results:

High CXCR4 expression was associated with large tumour size and metastatic disease. CXCR4 antagonists significantly reduced tumour cell invasiveness, while the treatment with rh-SDF1α stimulated invasive growth, caused cell cycle activation and induced EMT.

Conclusions:

The CXCR4/CXCR7/CXCL12 axis plays an important role in MTC. We provide first evidence that the chemokine receptors might serve as potential therapeutic targets in patients with advanced MTC and offer new valuable insight into the underlying molecular machinery of metastatic MTC.

Distinct mobilization of leukocytes and hematopoietic stem cells by CXCR4 peptide antagonist LY2510924 and monoclonal antibody LY2624587

Stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 play a critical role in mobilization and redistribution of immune cells and hematopoietic stem cells (HSCs). We evaluated effects of two CXCR4-targeting agents, peptide antagonist LY2510924 and monoclonal antibody LY2624587, on mobilizing HSCs and white blood cells (WBCs) in humans, monkeys, and mice. Biochemical analysis showed LY2510924 peptide blocked SDF-1/CXCR4 binding in all three species; LY2624587 antibody blocked binding in human and monkey, with minimal activity in mouse. Cellular analysis showed LY2624587 antibody, but not LY2510924 peptide, down-regulated cell surface CXCR4 and induced hematological tumor cell death; both agents have been shown to inhibit SDF-1/CXCR4 interaction and downstream signaling. In animal models, LY2510924 peptide induced robust, prolonged, dose- and time-dependent WBC and HSC increases in mice and monkeys, whereas LY2624587 antibody induced only moderate, transient increases in monkeys. In clinical trials, similar pharmacodynamic effects were observed in patients with advanced cancer: LY2510924 peptide induced sustained WBC and HSC increases, while LY2624587 antibody induced only minimal, transient WBC changes. These distinct pharmacodynamic effects in two different classes of CXCR4 inhibitors are clinically important and should be carefully considered when designing combination studies with immune checkpoint inhibitors or other agents for cancer therapy.

[Novel Immuno-oncology Therapy: Current Status of Clinical Research and Prospect of Application]

Recently, immune-oncologic therapy advanced rapidly and has been defined as another option, following surgery, radiotherapy, chemotherapy and molecular targeted therapy, for treatment of malignant diseases. To date, several immune checkpoint inhibitors and compounds have been approved to treat various of malignant diseases with efficiency. Meanwhile, more and more potential therapeutic targets in processes of the cancer immunity have been noticed. We aimed to summarize the research status and clinical prospects of novel immune-oncologic treatment agencies targeted to different steps of the cancer-immunity cycle.

Seek & Destroy, use of targeting peptides for cancer detection and drug delivery

Accounting for 16 million new cases and 9 million deaths annually, cancer leaves a great number of patients helpless. It is a complex disease and still a major challenge for the scientific and medical communities. The efficacy of conventional chemotherapies is often poor and patients suffer from off-target effects. Each neoplasm exhibits molecular signatures - sometimes in a patient specific manner - that may completely differ from the organ of origin, may be expressed in markedly higher amounts and/or in different location compared to the normal tissue. Although adding layers of complexity in the understanding of cancer biology, this cancer-specific signature provides an opportunity to develop targeting agents for early detection, diagnosis, and therapeutics. Chimeric antibodies, recombinant proteins or synthetic polypeptides have emerged as excellent candidates for specific homing to peripheral and central nervous system cancers. Specifically, peptide ligands benefit from their small size, easy and affordable production, high specificity, and remarkable flexibility regarding their sequence and conjugation possibilities. Coupled to imaging agents, chemotherapies and/or nanocarriers they have shown to increase the on-site delivery, thus allowing better tumor mass contouring in imaging and increased efficacy of the chemotherapies associated with reduced adverse effects. Therefore, some of the peptides alone or in combination have been tested in clinical trials to treat patients. Peptides have been well-tolerated and shown absence of toxicity. This review aims to offer a view on tumor targeting peptides that are either derived from natural peptide ligands or identified using phage display screening. We also include examples of peptides targeting the high-grade malignant tumors of the central nervous system as an example of the complex therapeutic management due to the tumor's location. Peptide vaccines are outside of the scope of this review.

CXCL12-CXCR4 Axis Is Required for Contact-Mediated Human B Lymphoid and Plasmacytoid Dendritic Cell Differentiation but Not T Lymphoid Generation

We investigated the involvement of CXCL12-CXCR4 interactions in human lymphohematopoiesis by coculture with telomerized human stromal cells. CXCR4 expression was low in CD34⁺CD38^-CD45RA^-CD10^-CD7^-CD19^- immature hematopoietic stem/precursor cells (HSPCs) but higher in CD34⁺CD38^-CD45RA⁺CD10⁺CD7^+/-CD19^- early lymphoid precursors and even higher in CD34⁺CD38⁺CD45RA⁺CD10⁺CD7^-CD19⁺ pro-B cells. Inhibition of the effect of stromal cell-produced CXCL12 by an anti-CXCR4-blocking Ab suppressed the generation of CD45RA⁺CD10^-CD7⁺CD19^- early T lymphoid precursors (ETPs) and CD45RA⁺CD10⁺CD7^-CD19^+/- B lymphoid precursors on stromal cells, but it did not affect the generation of ETPs in conditioned medium of stromal cell cultures. Replating assays showed that contact with stromal cells was critical for HSPC-derived CD45RA⁺CD10⁺CD7^-CD19^- B lineage-biased precursors to differentiate into CD19⁺ pro-B cells, which was suppressed by the anti-CXCR4 Ab. Conversely, HSPC-derived ETPs possessed T and B lymphoid and monocytic differentiation potential; stromal cell contact was not required for their growth but rather promoted B lymphoid differentiation. The anti-CXCR4 Ab did not affect the growth of ETPs in conditioned medium, but it suppressed their B lymphoid differentiation on stromal cells. CD14^-CD11c^-HLA-DR⁺CD123^highCD303⁺ plasmacytoid dendritic cells developed from HSPCs and ETPs exclusively in contact with stromal cells, which was suppressed by the anti-CXCR4 Ab. These data indicate that CXCL12 plays an essential role in stromal cell contact-mediated B lymphoid and plasmacytoid dendritic cell differentiation from immature hematopoietic and early T lymphoid precursors with a multilineage differentiation potential, but it does not participate in contact-independent generation of early T lymphoid precursors.

Screening of cancer tissue arrays identifies CXCR4 on adrenocortical carcinoma: correlates with expression and quantification on metastases using 64Cu-plerixafor PET

Expression of the chemokine receptor CXCR4 by many cancers correlates with aggressive clinical behavior. As part of the initial studies in a project whose goal was to quantify CXCR4 expression on cancers non-invasively, we examined CXCR4 expression in cancer samples by immunohistochemistry using a validated anti-CXCR4 antibody. Among solid tumors, we found expression of CXCR4 on significant percentages of major types of kidney, lung, and pancreatic adenocarcinomas, and, notably, on metastases of clear cell renal cell carcinoma and squamous cell carcinoma of the lung. We found particularly high expression of CXCR4 on adrenocortical cancer (ACC) metastases. Microarrays of ACC metastases revealed correlations between expression of CXCR4 and other chemokine system genes, particularly CXCR7/ACKR3, which encodes an atypical chemokine receptor that shares a ligand, CXCL12, with CXCR4. A first-in-human study using ⁶⁴Cu-plerixafor for PET in an ACC patient prior to resection of metastases showed heterogeneity among metastatic nodules and good correlations among PET SUVs, CXCR4 staining, and CXCR4 mRNA. Additionally, we were able to show that CXCR4 expression correlated with the rates of growth of the pulmonary lesions in this patient. Further studies are needed to understand better the role of CXCR4 in ACC and whether targeting it may be beneficial. In this regard, non-invasive methods for assessing CXCR4 expression, such as PET using ⁶⁴Cu-plerixafor, should be important investigative tools.

Epithelial-to-mesenchymal transition in FHC-silenced cells: the role of CXCR4/CXCL12 axis

Background

Ferritin plays a central role in the intracellular iron metabolism; the molecule is a nanocage of 24 subunits of the heavy and light types. The heavy subunit (FHC) is provided of a ferroxidase activity and thus performs the key transformation of iron in a non-toxic form. Recently, it has been shown that FHC is also involved in additional not iron-related critical pathways including, among the others, p53 regulation, modulation of oncomiRNAs expression and chemokine signalling. Epithelial to mesenchymal transition (EMT) is a cellular mechanism by which the cell acquires a fibroblast-like phenotype along with a decreased adhesion and augmented motility. In this work we have focused our attention on the role of the FHC on EMT induction in the human cell lines MCF-7 and H460 to elucidate the underlying molecular mechanisms.

Methods

Targeted silencing of the FHC was performed by lentiviral-driven shRNA strategy. Reconstitution of the FHC gene product was obtained by full length FHC cDNA transfection with Lipofectamine 2000. MTT and cell count assays were used to evaluate cell viability and proliferation; cell migration capability was assayed by the wound-healing assay and transwell strategy. Quantification of the CXCR4 surface expression was performed by flow cytometry.

Results

Experimental data indicated that FHC-silenced MCF-7 and H460 cells (MCF-7^shFHC, H460^shFHC) acquire a mesenchymal phenotype, accompanied by a significant enhancement of their migratory and proliferative capacity. This shift is coupled to an increase in ROS production and by an activation of the CXCR4/CXCL12 signalling pathway. We present experimental data indicating that the cytosolic increase in ROS levels is responsible for the enhanced proliferation of FHC-silenced cells, while the higher migration rate is attributable to a dysregulation of the CXCR4/CXCL12 axis.

Conclusions

Our findings indicate that induction of EMT, increased migration and survival depend, in MCF-7 and H460 cells, on the release of FHC control on two pathways, namely the iron/ROS metabolism and CXCR4/CXCL12 axis. Besides constituting a further confirmation of the multifunctional nature of FHC, this data also suggest that the analysis of FHC amount/function might be an important additional tool to predict tumor aggressiveness.

SDF-1/CXCR4 expression in head and neck cancer and outcome after postoperative radiochemotherapy

INTRODUCTION

Outcome after postoperative radiochemotherapy (RT-CT) for patients with advanced head and neck squamous cell carcinomas (HNSCC) remains unsatisfactory, especially among those with HPV negative tumours. Therefore, new biomarkers are needed to further define subgroups for individualised therapeutic approaches. Preclinical and first clinical observations showed that the chemokine receptor CXCR4 and its ligand SDF-1 (CXCL12) play an important role in tumour cell proliferation, survival, cancer progression, metastasis and treatment resistance. However, the data on the prognostic value of SDF-1/CXCR4 expression for HNSCC are conflicting. The aim of our hypothesis-generating study was to retrospectively explore the prognostic potential of SDF-1/CXCR4 in a well-defined cohort of HNSCC patients collected within the multicenter biomarker study of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG).

MATERIAL AND METHODS

Patients with stage III and IVA HNSCC of the oral cavity, oropharynx and hypopharynx were treated with resection and adjuvant radiotherapy (RT) with ≥60 Gy and concurrent cisplatin-based chemotherapy (CT). Tissue micro-arrays (TMAs) from a total of 221 patients were generated from surgical specimens, 201 evaluated for the SDF-1 and CXCR4 expression by immunofluorescence and correlated with clinico-pathological and outcome data.

RESULTS

In univariate and multivariate analyses intracellular SDF-1 expression was associated with lower loco-regional control (LRC) in the entire patient group as well as in the HPV16 DNA negative subgroup. CXCR4 expression showed a trend for lower LRC in the univariate analysis which was not confirmed in the multivariate analysis. Neither for SDF-1 nor CXCR4 expression associations with distant metastasis free or overall survival were found.

CONCLUSIONS

Our exploratory data support the hypothesis that overexpression of intracellular SDF-1 is an independent negative prognostic biomarker for LRC after postoperative RT-CT in high-risk HNSCC. Prospective validation is warranted and further exploration of SDF-1/CXCR4 as a potential therapeutic target to overcome treatment resistance in HNSCC appears promising.

Bruton's tyrosine kinase (BTK) as a promising target in solid tumors

Bruton's tyrosine kinase (BTK) is a non-receptor intracellular kinase that belongs to the TEC-family tyrosine kinases together with bone marrow-expressed kinase (BMX), redundant-resting lymphocyte kinase (RLK), and IL-2 inducible T-Cell kinase (ITK). All these proteins play a key role in the intracellular signaling of both B and T lymphocytes. Recently, some preclinical data have demonstrated that BTK is present in certain tumor subtypes and in other relevant cells that are contributing to the tumor microenvironment such as dendritic cells, macrophages, myeloid derived suppressor cells and endothelial cells. Ibrutinib (PCI-32765) is an orally available small molecule that acts as an inhibitor of the BTK and is approved for the treatment of patients with some hematological malignancies. It has been suggested that ibrutinib may also have a potential antitumor activity in solid neoplasms. In this sense, ibrutinib has the ability to revert polarization of TCD4+ to Th1 lymphocytes to increase the cytotoxic ability of T CD8+ and to regulate tumor-induced immune tolerance by acting over tumor infiltrating cells activity and immunosuppressive cytokines release. Furthermore, based on its molecular activity and safety, ibrutinib has been considered as a partner for treatment combination with PI3K/AKT/mTOR inhibitors or with immune-checkpoint inhibitors, inhibiting immunosuppressive signals from the tumor microenvironment, and overcoming the immune resistance to current anti-PD1/PDL1 immunotherapeutic drugs by the CXCR4/CXCL2 pathway regulation. Currently, a broad range of different studies are evaluating the activity of ibrutinib either as single agent or in combination in patients with solid tumors.

Downregulation of UHRF1 increases tumor malignancy by activating the CXCR4/AKT-JNK/IL-6/Snail signaling axis in hepatocellular carcinoma cells

UHRF1 (ubiquitin-like, with PHD and RING finger domains 1) plays a crucial role in DNA methylation, chromatin remodeling and gene expression and is aberrantly upregulated in various types of human cancers. However, the precise role of UHRF1 in cancer remains controversial. In this study, we observed that hypoxia-induced downregulation of UHRF1 contributes to the induction of the epithelial-mesenchymal transition (EMT) in hepatocellular carcinoma cells. By negatively modulating UHRF1 expression, we further showed that UHRF1 deficiency in itself is sufficient to increase the migratory and invasive properties of cells via inducing EMT, increasing the tumorigenic capacity of cells and leading to the expansion of cancer stem-like cells. Epigenetic changes caused by UHRF1 deficiency triggered the upregulation of CXCR4, thereby activating AKT and JNK to increase the expression and secretion of IL-6. In addition, IL-6 readily activated the JAK/STAT3/Snail signaling axis, which subsequently contributed to UHRF1 deficiency-induced EMT. Our results collectively demonstrate that UHRF1 deficiency may play a pivotal role in the malignant alteration of cancer cells.

A novel CXCR4-targeted near-infrared (NIR) fluorescent probe (Peptide R-NIR750) specifically detects CXCR4 expressing tumors

C-X-C chemokine receptor 4 (CXCR4) is over-expressed in multiple human cancers and correlates with tumor aggressiveness, poor prognosis and increased risk for distant metastases. Imaging agents for CXCR4 are thus highly desirable. We developed a novel CXCR4-targeted near-infrared (NIR) fluorescent probe (Peptide R-NIR750) conjugating the new developed CXCR4 peptidic antagonist Peptide R with the NIR fluorescent dye VivoTag-S750. Specific CXCR4 binding was obtained in cells overexpressing human CXCR4 (B16-hCXCR4 and human melanoma cells PES43), but not in CXCR4 low expressing cells (FB-1). Ex vivo evaluation demonstrated that PepR-NIR750 specifically detects B16-hCXCR4-derived subcutaneous tumors and lung metastases. Fluorescence Molecular Tomography (FMT) in vivo imaging was performed on mice carrying subcutaneous CHO and CHO-CXCR4 tumors. PepR-NIR750 accumulates only in CXCR4-positive expressing subcutaneous tumors. Additionally, an intense NIR fluorescence signal was detected in PES43-derived lung metastases of nude mice injected with PepR-NIR750 versus mice injected with VivoTag-S750. With a therapeutic intent, mice bearing PES43-derived lung metastases were treated with Peptide R. A the dramatic reduction in PES43-derived lung metastases was detected through a decrease of the PepR-NIR750 signal. PepR-NIR750 is a specific probe for non-invasive detection of human high CXCR4-expressing tumors and metastatic lesion and thus a valuable tool for cancer molecular imaging.

UTX promotes hormonally responsive breast carcinogenesis through feed-forward transcription regulation with estrogen receptor

UTX is implicated in embryonic development and lineage specification. However, how this X-linked histone demethylase contributes to the occurrence and progression of breast cancer remains to be clarified. Here we report that UTX is physically associated with estrogen receptor (ER) and functions in ER-regulated transcription. We showed that UTX coordinates with JHDM1D and CBP to direct H3K27 methylation-acetylation transition and to create a permissive chromatin state on ER targets. Genome-wide analysis of the transcriptional targets of UTX by ChIP-seq identified a set of genes such as chemokine receptor CXCR4 that are intimately involved in breast cancer tumorigenesis and metastasis. We demonstrated that UTX promotes the proliferation and migration of ER⁺ breast cancer cells. Interestingly, UTX itself is transactivated by ER, forming a feed-forward loop in the regulation of hormone response. Indeed, UTX is upregulated during ER⁺ breast cancer progression, and the expression level of UTX is positively correlated with that of CXCR4 and negatively correlated with the overall survival of ER⁺ breast cancer patients. Our study identified a feed-forward loop between UTX and ER in the regulation of hormonally responsive breast carcinogenesis, supporting the pursuit of UTX as an emerging therapeutic target for the intervention of certain ER⁺ breast cancer with specific epigenetic vulnerability.

Next Generation Sequencing Reveals Potentially Actionable Alterations in the Majority of Patients with Lymphoid Malignancies

Next generation sequencing (NGS) identifies alterations that may be potentially targetable by Food and Drug Administration (FDA) approved drugs and/or by available experimental agents that may not have otherwise been contemplated. Many targeted drugs have been developed for diverse solid cancers; a smaller number of genomically targeted drugs have been approved for lymphoid malignancies. We analyzed NGS results from 60 patients with various lymphoid malignancies and found a total of 224 alterations (median per patient = 3). Forty-nine patients (82%) had potentially actionable alterations using FDA-approved drugs and/or experimental therapies; only 11 patients (18%) had no theoretically actionable alterations. Only three patients (5%) had an alteration for which an approved drug in the disease is available (on-label); 45 patients (75%) had an alteration for which an approved drug is available in another disease (off-label). The median number of alterations per patient potentially actionable by an FDA-approved drug was 1. Interestingly, 19 of 60 patients (32%) had intermediate to high tumor mutational burden, which may predict response to certain immunotherapy agents. In conclusion, NGS identifies alterations that may be pharmacologically tractable in most patients with lymphoid malignancies, albeit with drugs that have usually been developed in the context of solid tumors. These observations merit expanded exploration in the clinical trials setting.

Phosphatidylcholine-specific phospholipase C inhibition down- regulates CXCR4 expression and interferes with proliferation, invasion and glycolysis in glioma cells

Background

The chemokine receptor CXCR4 plays a crucial role in tumors, including glioblastoma multiforme (GBM), the most aggressive glioma.

Phosphatidylcholine-specific phospholipase C (PC-PLC), a catabolic enzyme of PC metabolism, is involved in several aspects of cancer biology and its inhibition down-modulates the expression of growth factor membrane receptors interfering with their signaling pathways.

In the present work we investigated the possible interplay between CXCR4 and PC-PLC in GBM cells.

Methods

Confocal microscopy, immunoprecipitation, western blot analyses, and the evaluation of migration and invasion potential were performed on U87MG cells after PC-PLC inhibition with the xanthate D609. The intracellular metabolome was investigated by magnetic resonance spectroscopy; lactate levels and lactate dehydrogenase (LDH) activity were analyzed by colorimetric assay.

Results

Our studies demonstrated that CXCR4 and PC-PLC co-localize and are associated on U87MG cell membrane. D609 reduced CXCR4 expression, cell proliferation and invasion, interfering with AKT and EGFR activation and expression. Metabolic analyses showed a decrease in intracellular lactate concentration together with a decrement in LDH activity.

Conclusions

Our data suggest that inhibition of PC-PLC could represent a new molecular approach in glioma biology not only for its ability in modulating cell metabolism, glioma growth and motility, but also for its inhibitory effect on crucial molecules involved in cancer progression.

CXCR4/CXCL12/CXCR7 axis is functional in neuroendocrine tumors and signals on mTOR

Objective

To evaluate the possible crosstalk between C-X-C chemokine receptor 4 (CXCR4)/C-X-C motif chemokine 12 (CXCL12)/C-X-C chemokine receptor 7 (CXCR7) axis with the mammalian target of rapamycin (mTOR) pathway in neuroendocrine tumors (NETs).

Methods

Sixty-one human NETs were included into the study. CXCR4/CXCL12/CXCR7 axis and mTOR pathway were assessed by qRT-PCR and immunohistochemistry (IHC). The effect of mTOR inhibitor, RAD001, was evaluated on CXCR4 pathway through proliferation and p-Erk and p-AKT induction. Results: CXCR4/CXCL12/CXCR7 axis and p-mTOR were found to be active and correlated with grading, Ki67 index and tumor stage. mTOR pathway activation significantly correlated with poor prognosis. In human NET cells, CXCL12 induced mTOR signalling while AMD3100 (CXCR4-antagonist) impaired it. The mTOR-antagonist, RAD001, impaired the CXCL12-dependent induction of CXCR4 downstream effectors. Combination of AMD3100 and RAD001 potentiate cell growth inhibition.

Conclusions

CXCR4/CXCL12/CXCR7 axis is active in NETs and signals on mTOR. CXCR4 might be considered a prognostic factor in NETs. Combined treatment with AMD3100 and RAD001 may provide clinical benefits in NET patients with drug-resistant.

Effect of PD-1: PD-L1 in Invariant Natural Killer T-Cell Emigration and Chemotaxis Following Sepsis

Invariant natural killer T-cells (iNKT) are a subset of T-cells that play a regulatory role in sepsis. Following cecal ligation and puncture (CLP), iNKT cells emigrate from the liver and into the circulation and peritoneum in a manner dependent upon coinhibitory molecule Programmed Cell Death Receptor 1 (PD-1). We hypothesized that the effect of PD-1 on iNKT-cell emigration was dependent upon the direct PD-1:PD-L1 interaction, and that PD-1 and PD-L1 would play a role in chemotaxis and chemokine receptor expression. Adoptive transfer of Vybrant-labeled wild-type (WT) cells showed the donor iNKT cells migrated from the liver to the peritoneum following CLP, but PD-L1 deficient donor iNKT cells did not. In a chemotaxis assay, WT-iNKT cells chemotaxed to CXCL12, but PD-1 and PD-L1 deficient iNKT cells did not. Using flow cytometry to evaluate chemokine receptor expression, peritoneal iNKT expression of CXCR4 increased following CLP in the WT, PD-1, and PD-L1 deficient animals, and CXCR6 increased in the WT and PD-1 deficient animals. In conclusion here we document that the hepatic emigration of iNKT cells following CLP to the peritoneum appears dependent upon the direct PD-1:PD-L1 interaction; however, although PD-1 and PD-L1 appear to play a role in chemotaxis, this is unlikely a reflection of iNKT-cell chemokine receptor expression changes.

Exploring the N-Terminal Region of C-X-C Motif Chemokine 12 (CXCL12): Identification of Plasma-Stable Cyclic Peptides As Novel, Potent C-X-C Chemokine Receptor Type 4 (CXCR4) Antagonists

We previously reported the discovery of a CXCL12-mimetic cyclic peptide (2) as a selective CXCR4 antagonist showing promising in vitro and in vivo anticancer activity. However, further development of this peptide was hampered by its degradation in biological fluids as well as by its low micromolar affinity for the receptor. Herein, extensive chemical modifications led to the development of a new analogue (10) with enhanced potency, specificity, and plasma stability. A combined approach of Ala-amino acid scan, NMR, and molecular modeling unraveled the reasons behind the improved binding properties of 10 vs 2. Biological investigations on leukemia (CEM) and colon (HT29 and HCT116) cancer cell lines showed that 10 is able to impair CXCL12-mediated cell migration, ERK-phosphorylation, and CXCR4 internalization. These outcomes might pave the way for the future preclinical development of 10 in CXCR4 overexpressing leukemia and colon cancer.

LncRNAs expression in adjuvant-induced arthritis rats reveals the potential role of LncRNAs contributing to rheumatoid arthritis pathogenesis

BACKGROUND

Long non-coding RNAs (LncRNAs) are an important class of widespread molecules involved in diverse biological functions, which are exceptionally expressed in numerous types of diseases. Currently, limited study on LncRNA in rheumatoid arthritis (RA) is available. In this study, we aimed to identify the specifically expressed LncRNA that are relevant to adjuvant-induced arthritis (AA) in rats, and to explore the possible molecular mechanisms of RA pathogenesis.

METHODS

To identify LncRNAs specifically expressed in rheumatoid arthritis, the expression of LncRNAs in synoviums of rats from the model group (n=3) was compared with that in the control group (n=3) using Arraystar Rat LncRNA/mRNA microarray and real-time polymerase chain reaction (RT-PCR).

RESULTS

Up to 260 LncRNAs were found to be differentially expressed (≥1.5-fold-change) in the synoviums between AA model and the normal rats (170 up-regulated and 90 down-regulated LncRNAs in AA rats compared with normal rats). Coding-non-coding gene co-expression networks (CNC network) were drawn based on the correlation analysis between the differentially expressed LncRNAs and mRNAs. Six LncRNAs, XR_008357, U75927, MRAK046251, XR_006457, DQ266363 and MRAK003448, were selected to analyze the relationship between LncRNAs and RA via the CNC network and GO analysis. Real-time PCR result confirmed that the six LncRNAs were specifically expressed in the AA rats.

CONCLUSIONS

These results revealed that clusters of LncRNAs were uniquely expressed in AA rats compared with controls, which manifests that these differentially expressed LncRNAs in AA rats might play a vital role in RA development. Up-regulation or down-regulation of the six LncRNAs might contribute to the molecular mechanism underlying RA. To sum up, our study provides potential targets for treatment of RA and novel profound understanding of the pathogenesis of RA.

Polymeric chloroquine as an inhibitor of cancer cell migration and experimental lung metastasis

Chloroquine (CQ) is a widely used antimalarial drug with emerging potential in anticancer therapies due to its apparent inhibitory effects on CXCR4 chemokine receptor, autophagy, and cholesterol metabolism. This study reports on polymeric CQ (pCQ) as a macromolecular drug with antimetastatic activity. The pCQ polymers were synthesized by copolymerization of methacryloylated hydroxy-CQ (HCQ) and N-(2-hydroxypropyl)methacrylamide (HPMA). The results show that pCQ is significantly more effective in inhibiting cancer cell migration and invasion when compared with the parent HCQ. The proposed mechanism of action at least partially relies on the ability of pCQ to inhibit cell migration mediated by the CXCR4/CXCL12 pathway. The pCQ also demonstrates superior inhibitory activity over HCQ when tested in a mouse model of experimental lung metastasis. Lastly, pCQ shows the ability to efficiently translocate to the cytoplasm while exhibiting lower cytotoxicity than HCQ. Overall, this study supports pCQ as a promising polymeric drug platform suitable for use in combination antimetastatic strategies and potential use in cytoplasmic drug delivery.