Novel cellular genes essential for transformation of endothelial cells by Kaposi's sarcoma-associated herpesvirus

The Kaposi's sarcoma progenitor enigma: KSHV-induced MEndT-EndMT axis

Endothelial-to-mesenchymal transition has been described in tumors as a source of mesenchymal stroma, while the reverse process has been proposed in tumor vasculogenesis and angiogenesis. A human oncogenic virus, Kaposi's sarcoma herpes virus (KSHV), can regulate both processes in order to transit through this transition 'boulevard' when infecting KS oncogenic progenitor cells. Endothelial or mesenchymal circulating progenitor cells can serve as KS oncogenic progenitors recruited by inflammatory cytokines because KSHV can reprogram one into the other through endothelial-to-mesenchymal and mesenchymal-to-endothelial transitions. Through these novel insights, the identity of the potential oncogenic progenitor of KS is revealed while gaining knowledge of the biology of the mesenchymal-endothelial differentiation axis and pointing to this axis as a therapeutic target in KS.

25-Hydroxycholesterol Inhibits Kaposi's Sarcoma Herpesvirus and Epstein-Barr Virus Infections and Activates Inflammatory Cytokine Responses

Oncogenic gammaherpesviruses express viral products during latent and lytic infection that block the innate immune response. Previously, we found that Kaposi's sarcoma herpesvirus (KSHV/human herpesvirus-8) viral microRNAs (miRNAs) downregulate cholesterol biogenesis, and we hypothesized that this prevents the production of 25-hydroxycholesterol (25HC), a cholesterol derivative. 25HC blocks KSHV de novo infection of primary endothelial cells at a postentry step and decreases viral gene expression of LANA (latency-associated nuclear antigen) and RTA. Herein we expanded on this observation by determining transcriptomic changes associated with 25HC treatment of primary endothelial cells using RNA sequencing (RNA-Seq). We found that 25HC treatment inhibited KSHV gene expression and induced interferon-stimulated genes (ISGs) and several inflammatory cytokines (interleukin 8 [IL-8], IL-1α). Some 25HC-induced genes were partially responsible for the broadly antiviral effect of 25HC against several viruses. Additionally, we found that 25HC inhibited infection of primary B cells by a related oncogenic virus, Epstein-Barr virus (EBV/human herpesvirus-4) by suppressing key viral genes such as LMP-1 and inducing apoptosis. RNA-Seq analysis revealed that IL-1 and IL-8 pathways were induced by 25HC in both primary endothelial cells and B cells. We also found that the gene encoding cholesterol 25-hydroxylase (CH25H), which converts cholesterol to 25HC, can be induced by type I interferon (IFN) in human B cell-enriched peripheral blood mononuclear cells (PBMCs). We propose a model wherein viral miRNAs target the cholesterol pathway to prevent 25HC production and subsequent induction of antiviral ISGs. Together, these results answer some important questions about a widely acting antiviral (25HC), with implications for multiple viral and bacterial infections. IMPORTANCE A cholesterol derivative, 25-hydroxycholesterol (25HC), has been demonstrated to inhibit infections from widely different bacteria and viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, its mechanism of activity is still not fully understood. In this work, we look at gene expression changes in the host and virus after 25HC treatment to find clues about its antiviral activity. We likewise demonstrate that 25HC is also antiviral against EBV, a common cancer-causing virus. We compared our results with previous data from antiviral screening assays and found the same pathways resulting in antiviral activity. Together, these results bring us closer to understanding how a modified form of cholesterol works against several viruses.

Clinicopathological and Preclinical Patient-Derived Model Studies Define High Expression of NRN1 as a Diagnostic and Therapeutic Target for Clear Cell Renal Cell Carcinoma

Background

Acquired therapeutic resistance and metastasis/recurrence remain significant challenge in advance renal cell carcinoma (RCC), thus the establishment of patient-derived cancer models may provide a clue to assess the problem. We recently characterized that neuritogenesis-related protein neuritin 1 (NRN1) functions as an oncogene in testicular germ cell tumor. This study aims to elucidate the role of NRN1 in RCC.

Methods

NRN1 expression in clinical RCC specimens was analyzed based on immunohistochemistry. NRN1-associated genes in RCC were screened by the RNA-sequencing dataset from The Cancer Genome Atlas (TCGA). RCC patient-derived cancer cell (RCC-PDC) spheroid cultures were established and their viabilities were evaluated under the condition of gene silencing/overexpression. The therapeutic effect of NRN1-specific siRNA was evaluated in RCC-PDC xenograft models.

Results

NRN1 immunoreactivity was positively associated with shorter overall survival in RCC patients. In TCGA RCC RNA-sequencing dataset, C-X-C chemokine receptor type 4 (CXCR4), a prognostic and stemness-related factor in RCC, is a gene whose expression is substantially correlated with NRN1 expression. Gain- and loss-of-function studies in RCC-PDC spheroid cultures revealed that NRN1 significantly promotes cell viability along with the upregulation of CXCR4. The NRN1-specific siRNA injection significantly suppressed the proliferation of RCC-PDC-derived xenograft tumors, in which CXCR4 expression is significantly repressed.

Conclusion

NRN1 can be a potential diagnostic and therapeutic target in RCC as analyzed by preclinical patient-derived cancer models and clinicopathological studies.

CXCL12-CXCR4/CXCR7 Axis in Colorectal Cancer: Therapeutic Target in Preclinical and Clinical Studies

Chemokines are chemotactic cytokines that promote cancer growth, metastasis, and regulate resistance to chemotherapy. Stromal cell-derived factor 1 (SDF1) also known as C-X-C motif chemokine 12 (CXCL12), a prognostic factor, is an extracellular homeostatic chemokine that is the natural ligand for chemokine receptors C-X-C chemokine receptor type 4 (CXCR4), also known as fusin or cluster of differentiation 184 (CD184) and chemokine receptor type 7 (CXCR7). CXCR4 is the most widely expressed rhodopsin-like G protein coupled chemokine receptor (GPCR). The CXCL12-CXCR4 axis is involved in tumor growth, invasion, angiogenesis, and metastasis in colorectal cancer (CRC). CXCR7, recently termed as atypical chemokine receptor 3 (ACKR3), is amongst the G protein coupled cell surface receptor family that is also commonly expressed in a large variety of cancer cells. CXCR7, like CXCR4, regulates immunity, angiogenesis, stem cell trafficking, cell growth and organ-specific metastases. CXCR4 and CXCR7 are expressed individually or together, depending on the tumor type. When expressed together, CXCR4 and CXCR7 can form homo- or hetero-dimers. Homo- and hetero-dimerization of CXCL12 and its receptors CXCR4 and CXCR7 alter their signaling activity. Only few drugs have been approved for clinical use targeting CXCL12-CXCR4/CXCR7 axis. Several CXCR4 inhibitors are in clinical trials for solid tumor treatment with limited success whereas CXCR7-specific inhibitors are still in preclinical studies for CRC. This review focuses on current knowledge of chemokine CXCL12 and its receptors CXCR4 and CXCR7, with emphasis on targeting the CXCL12-CXCR4/CXCR7 axis as a treatment strategy for CRC.

Neuritin promotes angiogenesis through inhibition of DLL4/Notch signaling pathway

Neuritin is a member of the neurotrophic factor family, which plays an important role in the promotion and development of the nervous system. Neuritin is also involved in angiogenesis. Neuritin was recently found to be a negative regulatory factor of the Notch 1 signaling pathway. Notch signaling pathway is known as a regulatory pathway of angiogenesis. Thus, neuritin may play a role in angiogenesis through the Notch signaling pathway. In the present study, we investigated the expressions of neuritin and Notch signaling pathway factors in the pulmonary vascular tissue. The results showed that neuritin expression was increased in the paraneoplastic vascular tissue and decreased in the lung cancer vascular tissue. The neuritin expression was increased with the increase of vascular tissue density, and a negative correlation between neuritin expression and delta-like ligand 4 (DLL4) was identified in vascular tissues of lung cancer. Overexpression of neuritin in human umbilical vein endothelial cells (HUVECs) inhibited the expressions of Notch signaling pathway-associated factors, including DLL4, NICD, and Hes-1, and promoted the migration and tubular formation of HUVECs. In conclusion, our results indicated that neuritin is involved in angiogenesis and may play a role in angiogenesis through the Notch signaling pathway. This study provides a theoretical basis for clinical anti-angiogenesis therapy.

Chemokines as the critical factors during bladder cancer progression: an overview

Bladder cancer (BCa) is one of the most frequent urogenital malignancies which is mainly observed among men. There are various genetic and environmental risk factors associated with BCa progression. Transurethral endoscopic resection and open ablative surgery are the main treatment options for muscle invasive BCa. BCG therapy is also employed following the endoscopic resection to prevent tumor relapse. The tumor microenvironment is the main interaction site of tumor cells and immune system in which the immune cells are recruited via chemokines and chemokine receptors. In present review we summarized the main chemokines and chemokine receptors which have been associated with histopathological features of BCa patients in the world. This review highlights the chemokines and chemokine receptors as critical markers in early detection and therapeutic purposes among BCa patients and clarifies their molecular functions during BCa progression and metastasis.

Neuritin-overexpressing transgenic mice demonstrate enhanced neuroregeneration capacity and improved spatial learning and memory recovery after ischemia-reperfusion injury

Acute ischemia-reperfusion (IR)-induced brain injury is further exacerbated by a series of slower secondary pathogenic events, including delayed apoptosis due to neurotrophic factor deficiency. Neuritin, a neurotrophic factor regulating nervous system development and plasticity, is a potential therapeutic target for treatment of IR injury. In this study, Neuritin-overexpressing transgenic (Tg) mice were produced by pronuclear injection and offspring with high overexpression used to generate a line with stable inheritance for testing the neuroprotective capacity of Neuritin against transient global ischemia (TGI). Compared to wild-type mice, transgenic mice demonstrated reduced degradation of the DNA repair factor poly [ADP-ribose] polymerase 1 (PARP 1) in the hippocampus, indicating decreased hippocampal apoptosis rate, and a greater number of surviving hippocampal neurons during the first week post-TGI. In addition, Tg mice showed increased expression of the regeneration markers NF-200, synaptophysin, and GAP-43, and improved recovery of spatial learning and memory. Our findings exhibited that the window of opportunity of neural recovery in Neuritin transgenic mice group had a tendency to move ahead after TGI, which indicated that Neuritin can be used as a potential new therapeutic strategy for improving the outcome of cerebral ischemia injury.

Wogonin reverses the drug resistance of chronic myelogenous leukemia cells to imatinib through CXCL12-CXCR4/7 axis in bone marrow microenvironment

Background

In the current study, chronic myeloid leukemia (CML) cells (K562 and KU812) co-cultured with human bone marrow stromal cells (BMSCs) were significantly less sensitive to imatinib (IM). The activation of the CXCL12-CXCR4/7 axis plays an important role in the protective effect of the bone marrow microenvironment (BME) on CML cells. The aim of this study was to investigate whether Wogonin could increase the sensitivity of CML cells to IM when they were co-cultured with BME and explore its underlying mechanism.

Methods

A model of CML cells co-cultured with BMSCs was applied in vitro. Flow cytometric, western blotting, immunofluorescence, and RT-PCR assays were used to explore the protective effects of BME on CML cells.

Results

The results showed that Wogonin could reverse the resistance of CML cells to IM under co-culture conditions by inhibiting Transforming growth factor-β (TGF-β) secretion in the BME, preventing the translocation of Smad4 into nucleus and subsequently reducing the expression of CXCR4 and CXCR7 in CML cells. Moreover, the reverse effect of Wogonin was demonstrated by inhibiting the activation of CXCL12-CXCR4/7 axis via restraining the TGF-β/Smad4/Id3 pathway in vitro. In vivo studies also showed that Wogonin decreased the expression of CXCR4 and CXCR7 in mice bone marrow with low systemic toxicity, and the mechanism was consistent with the in vitro study.

Conclusions

Wogonin increases the sensitivity of CML cells to IM in BME by controlling the TGF-β/Smad4/Id3 pathway and decreasing the expression of CXCR4 and CXCR7. These results co-supported the point that Wogonin could be a potential candidate of reversal agents on treatment of IM-resistant CML.

HIF1α inhibitor 2-methoxyestradiol decreases NRN1 expression and represses in vivo and in vitro growth of patient-derived testicular germ cell tumor spheroids

Testicular germ cell tumor (GCT) is the most common type of malignancy in young males. Patients with nonseminomatous GCT still have poor prognosis. To identify new therapeutic targets, we generated patient-derived cells (PDCs) and their xenograft (PDCX) models from 3 distinct GCT patients' specimens. The pathological features of GCT PDCs and PDCX tumors recapitulated those of nonseminomatous components exhibiting in the corresponding patients' specimens. Notably, stemness-related markers and hypoxia-related genes, including hypoxia inducible factor 1α (HIF1A) and neuritin 1 (NRN1), were abundantly expressed in three-dimensional spheroid cultures of GCT PDCs. We identified functional HIF1α response elements in the NRN1 promoter and defined that their transcriptional activities were substantially activated by hypoxia. HIF1α inhibition by siRNAs or an inhibitor, 2-methoxyestradiol, significantly suppressed NRN1 expression and decreased the in vitro and in vivo growth of PDC spheroids. Moreover, NRN1 knockdown efficiently suppressed PDC proliferation. These results suggest that HIF1α and NRN1 are potential diagnostic and therapeutic targets, and that 2-methoxyestradiol could be applied to clinical management of GCT. Overall, our GCT PDC and PDCX models would be useful as preclinical models for precision medicine targeting each patient.

The Biological-Behavioral Effect Of Neuritin On Non-Small Cell Lung Cancer Vascular Endothelial Cells Via VEGFR And Notch1

Purpose

This study aims to elucidate the biological behavior of Neuritin abnormal expression in pulmonary vascular endothelial cells (VECs) of non-small cell lung cancer (NSCLC), and explore its possible underlying mechanisms.

Patients and methods

Primary NSCLC-VECs were isolated from 10 cancer tissues from NSCLC patients, purified and identified by CD34 and Factor VIII staining. Real-time PCR and Western-blot were adopted for detecting the expression levels of Neuritin, Notch1, and VEGFR in NSCLC-VECs and HPMECs. Neuritin-overexpression, Neuritin-knockdown NSCLC-VECs and HPMECs were constructed by transfection of pcDNA3, 1-Neuritin vector, and pBS/U6-Neuritin siRNA. Changes in cell proliferation, migration, cell cycle, and apoptosis were determined by using the MTT assay, scratch assay, transwell migration assay, and flow cytometry, respectively. Post-transfection changes in cell morphology were examined by scanning electron microscopy.

Results

The expression of Neuritin in NSCLC-VECs was significantly higher compared to that in HPMECs (p<0.01). Overexpression of Neuritin increased the expression of VEGFR while it reduced the expression of Notch1 (p<0.01); it also promoted cell proliferation, scratch healing, and in vitro migration (p<0.05) in HPMECs and NSCLC-VECs cells. Additionally, overexpression of Neuritin stimulated cell cycle progression and inhibited apoptosis in HPMECs and NSCLC-VECs (p<0.001). Under electron microscope, the pseudopodium of cell surface was obvious, indicating that the intercellular adhesion was upregulated. However, knockdown of Neuritin in HPMECs and NSCLC-VECs played exactly the opposite roles.

Conclusion

Neuritin was key in the progression of NSCLC through its biological activities, including anti-apoptosis, promoting VEC proliferation, migration, and cell cycle progression. Neuritin may affect its biological activity by positively regulating VEGFR expression and negatively regulating Notch1 signaling. Neuritin may serve as a potential biomarker for NSCLC.

Role of CXCR7 as a Common Predictor for Prognosis in Solid Tumors: a Meta-Analysis

Background: Accumulating evidence indicated that the CXC chemokine receptor (CXCR) 7 (CXCR7) was overexpressed in a variety of tumors. However, the value of the CXCR7 expression in predicting prognosis in solid tumors remains controversial. Therefore, we performed this meta-analysis to evaluate the correlation between CXCR7 expression and lymph node metastasis (LNM), tumor pathological grade and survival, including overall survival (OS), disease-free survival (DFS) and recurrence-free survival (RFS). Methods: Eligible studies were searched in PubMed, Web of Science, and PMC up to April 2018. A total of 27 studies were included in this meta-analysis. Odds ratio (OR), hazard ratio (HR) and 95 % confidence intervals (CI) were used as effect measures. Results: The meta-analysis showed that high expression of CXCR7 predicted a high risk of LNM (pooled OR = 2.22, 95%CI: 1.41-3.50), high tumor grade (pooled OR = 1.94, 95%CI: 1.20-3.13), poor OS (pooled HR = 1.66, 95%CI: 1.30-2.03), and poor DFS/RFS (pooled HR = 1.82, 95%CI: 1.21-2.43). Subgroup analysis showed that CXCR7 expression had a positive correlation with LNM in pan-adenocarcinoma subgroup (pooled OR = 3.73, 95%CI: 2.21-6.30), while no correlation was found in pan-squamous cancer subgroup (pooled OR = 1.29, 95%CI: 0.56-2.96). Subgroup analysis of tumor grade revealed that high expression of CXCR7 predicted high tumor grade both in pan-squamous cancer and pan-adenocarcinoma (pooled OR = 3.58, 95%CI: 1.39-9.22, pooled OR = 2.25, 95%CI: 1.20-4.20). As in OS group, we divided the data based on analysis method and it turned out that overexpressed CXCR7 predicted worse OS both in multivariate analysis (pooled HR =1.57, 95%CI: 1.12-2.01) and univariate analysis subgroup (pooled HR =1.86, 95%CI: 1.23-2.49). Conclusions: Our meta-analysis revealed that high expression of CXCR7 predicted unfavorable prognosis and may serve as potential targets of cancer therapy.

The neurotrophin Neuritin1 (cpg15) is involved in melanoma migration, attachment independent growth, and vascular mimicry

The neurotrophin Neuritin1 (NRN1; cpg15) belongs to the candidate plasticity gene (CPG) family and is expressed in postmitotic-differentiating neurons of the developmental nervous system and neuronal structures associated with plasticity in the brain of human adult.Our newest findings document that NRN1 deregulation could contribute also to disease development and have impact on malignant melanoma. Our analyses displayed the over-expression of NRN1 in melanoma in vitro and in vivo, shown by immunohistochemistry and qRT-PCR on microdissected melanoma tissue; furthermore, soluble NRN1 was detectable in tissue culture supernatant and serum of melanoma patients.To investigate the role of NRN1 in melanoma we performed knockdown, over-expression and recombinant-NRN1-treatment experiments affiliated by functional assays. Our results show that migration, attachment independent growth and vasculogenesis were affected after manipulation of NRN1 on endogenous and extrinsic level. Interestingly, high NRN1 serum levels correlate with low MIA serum levels (< 10ng/ml). Therefore, we speculate that NRN1 could be a marker for early melanoma stages, in particular.In summary, we detected an overexpression of NRN1 in melanoma patient. In functional cell culture experiments we found a correlation between NRN1 expression and the cancerous behavior of melanoma cells.

BH3 mimetics suppress CXCL12 expression in human malignant peripheral nerve sheath tumor cells

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive, Schwann cell-derived neoplasms of the peripheral nervous system that have recently been shown to possess an autocrine CXCL12/CXCR4 signaling loop that promotes tumor cell proliferation and survival. Importantly, the CXCL12/CXCR4 signaling axis is driven by availability of the CXCL12 ligand rather than CXCR4 receptor levels alone. Therefore, pharmacological reduction of CXCL12 expression could be a potential chemotherapeutic target for patients with MPNSTs or other pathologies wherein the CXCL12/CXCR4 signaling axis is active. AT101 is a well-established BCL-2 homology domain 3 (BH3) mimetic that we recently demonstrated functions as an iron chelator and thus acts as a hypoxia mimetic. In this study, we found that AT101 significantly reduces CXCL12 mRNA and secreted protein in established human MPNST cell lines in vitro. This effect was recapitulated by other BH3 mimetics [ABT-737 (ABT), obatoclax (OBX) and sabutoclax (SBX)] but not by desferrioxamine (DFO), an iron chelator and known hypoxia mimetic. These data suggest that CXCL12 reduction is a function of AT101's BH3 mimetic property rather than its iron chelation ability. Additionally, this study investigates a potential mechanism of BH3 mimetic-mediated CXCL12 suppression: liberation of a negative CXCL12 transcriptional regulator, poly (ADP-Ribose) polymerase I (PARP1) from its physical interaction with BCL-2. These data suggest that clinically available BH3 mimetics might prove therapeutically useful at least in part by virtue of their ability to suppress CXCL12 expression.

Biological/pathological functions of the CXCL12/CXCR4/CXCR7 axes in the pathogenesis of bladder cancer

CXC chemokine ligand 12 (CXCL12) is an important member of the CXC subfamily of chemokines, and has been extensively studied in various human body organs and systems, both in physiological and clinical states. Ligation of CXCL12 to CXCR4 and CXCR7 as its receptors on peripheral immune cells gives rise to pleiotropic activities. CXCL12 itself is a highly effective chemoattractant which conservatively attracts lymphocytes and monocytes, whereas there exists no evidence to show attraction for neutrophils. CXCL12 regulates inflammation, neo-vascularization, metastasis, and tumor growth, phenomena which are all pivotally involved in cancer development and further metastasis. Generation and secretion of CXCL12 by stromal cells facilitate attraction of cancer cells, acting through its cognate receptor, CXCR4, which is expressed by both hematopoietic and non-hematopoietic tumor cells. CXCR4 stimulates tumor progression by different mechanisms and is required for metastatic spread to organs where CXCL12 is expressed, thereby allowing tumor cells to access cellular niches, such as the marrow, which favor tumor cell survival and proliferation. It has also been demonstrated that CXCL12 binds to another seven-transmembrane G-protein receptor or G-protein-coupled receptor, namely CXCR7. These studies indicated critical roles for CXCR4 and CXCR7 mediation of tumor metastasis in several types of cancers, suggesting their contributions as biomarkers of tumor behavior as well as potential therapeutic targets. Furthermore, CXCL12 itself has the capability to stimulate survival and growth of neoplastic cells in a paracrine fashion. CXCL12 is a supportive chemokine for tumor neovascularization via attracting endothelial cells to the tumor microenvironment. It has been suggested that elevated protein and mRNA levels of CXCL12/CXCR4/CXCR7 are associated with human bladder cancer (BC). Taken together, mounting evidence suggests a role for CXCR4, CXCR7, and their ligand CXCL12 during the genesis of BC and its further development. However, a better understanding is still required before exploring CXCL12/CXCR4/CXCR7 targeting in the clinic.

An In Vitro Model for Studying Cellular Transformation by Kaposi Sarcoma Herpesvirus

Kaposi sarcoma (KS) is an unusual tumor composed of proliferating spindle cells that is initiated by infection of endothelial cells (EC) with KSHV, and develops most often in the setting of immunosuppression. Despite decades of research, optimal treatment of KS remains poorly defined and clinical outcomes are especially unfavorable in resource-limited settings. KS lesions are driven by pathological angiogenesis, chronic inflammation, and oncogenesis, and various in vitro cell culture models have been developed to study these processes. KS arises from KSHV-infected cells of endothelial origin, so EC-lineage cells provide the most appropriate in vitro surrogates of the spindle cell precursor. However, because EC have a limited in vitro lifespan, and as the oncogenic mechanisms employed by KSHV are less efficient than those of other tumorigenic viruses, it has been difficult to assess the processes of transformation in primary or telomerase-immortalized EC. Therefore, a novel EC-based culture model was developed that readily supports transformation following infection with KSHV. Ectopic expression of the E6 and E7 genes of human papillomavirus type 16 allows for extended culture of age- and passage-matched mock- and KSHV-infected EC and supports the development of a truly transformed (i.e., tumorigenic) phenotype in infected cell cultures. This tractable and highly reproducible model of KS has facilitated the discovery of several essential signaling pathways with high potential for translation into clinical settings.

The potential of stromal cell-derived factor-1 delivery using a collagen membrane for bone regeneration

Stromal cell-derived factor-1 (SDF-1) is a cytokine that is important in stem and progenitor cell recruitment in tissue repair after injury. Regenerative procedures using collagen membranes (CMs) are presently well established in periodontal and implant dentistry. The objective of this study is to test the subsequent effects of the released SDF-1 from a CM on bone regeneration compared to platelet-derived growth factor (PDGF) in vitro and in vivo. For in vitro studies, cell proliferation, alkaline phosphatase activity, and osteoblastic differentiation marker genes were assessed after MC3T3-E1 mouse preosteoblasts were cultured with CMs containing factors. In vivo effects were investigated by placement of CMs containing SDF-1 or PDGF using a rat mandibular bone defect model. At 4 weeks after the surgery, the new bone formation was measured using micro-computed tomography (µCT) and histological analysis. The results of in vitro studies revealed that CM delivery of SDF-1 significantly induced cell proliferation, ALP activity, and gene expression of all osteogenic markers compared to the CM alone or control, similar to PDGF. Quantitative and qualitative µCT analysis for volume of new bone formation and the percentage of new bone area showed that SDF-1-treated groups significantly increased and accelerated bone regeneration compared to control and CM alone. The enhancement of bone formation in SDF-1-treated animals was dose-dependent and with levels similar to those measured with PDGF. These results suggest that a CM with SDF-1 may be a great candidate for growth factor delivery that could be a substitute for PDGF in clinical procedures where bone regeneration is necessary.

C-Kit, CD34 & α-SMA Immunohistochemical Features in Classic Kaposi Sarcoma and Kaposiform Hemangioendothelioma

PURPOSE & METHODS

The aim of this work was to study the clinicopathological features of Kaposi sarcoma (KS) & kaposiform hemangioendothelioma (KHE) and analyze their immunohistochemical expression of c-Kit, CD34, α-SMA. The study was performed on cutaneous 10 classic KS & 8 KHE.

RESULTS

KHE shows several dilated lymphatic channels, focal capillary formation, lack of nuclear atypia and mitosis within tumor cells. These features help to exclude Kaposi sarcoma in spite of the kaposiform pattern of tumor cells. C-Kit was expressed by tumor cells in all KHE cases and in 60% only of KS. All elements within both tumor groups expressed CD34 antibody. α-SMA was expressed by tumor cells in 70% of KS cases and none of KHE.

CONCLUSION

C-Kit and CD34 seem to be reliable at labeling KS and KHE as they can help in diagnosis of these tumors in routinely processed tissue but they don't differentiate between them. If α-SMA also labeled the tumor, then KHE diagnosis can be ruled out. KS & KHE exemplify stem cell tumors that could give smooth muscle cell-like phenotype in KS. Anti C-kit therapy should be tested in KS & KHE to prevent recurrence.

Kaposi's Sarcoma-Associated Herpesvirus: Epidemiology and Molecular Biology

Kaposi's sarcoma-associated herpesvirus (KSHV), also known as Human herpesvirus 8 (HHV-8), is a member of the lymphotropic gammaherpesvirus subfamily and a human oncogenic virus. Since its discovery in AIDS-associated KS tissues by Drs. Yuan Chang and Patrick Moore, much progress has been made in the past two decades. There are four types of KS including classic KS, endemic KS, immunosuppressive therapy-related KS, and AIDS-associated KS. In addition to KS, KSHV is also involved in the development of primary effusion lymphoma (PEL) and certain types of multicentric Castleman's disease. KSHV manipulates numerous viral proteins to promote the progression of angiogenesis and tumorigenesis. In this chapter, we review the epidemiology and molecular biology of KSHV and the mechanisms underlying KSHV-induced diseases.

Oroxylin A reverses the drug resistance of chronic myelogenous leukemia cells to imatinib through CXCL12/CXCR7 axis in bone marrow microenvironment

Imatinib (IM), a tyrosine-kinase inhibitor, is used in treatment of multiple cancers, most notably Philadelphia chromosome-positive (Ph⁺ ) chronic myelogenous leukemia (CML). However, the majority of patients continue to present with minimal residual disease occurred in the bone marrow (BM) microenvironment. One of the key factors that contribute to leukemia cell drug resistance is chemokine CXCL12. In the current study, co-culturing CML cell K562 and KU812 with BM stromal cell M2-10B4 attenuated IM-induced apoptosis. CXCL12/CXCR7 pathway was activated in co-culture models, which was further proved to be related to drug resistance by silencing CXCR7. ERK phosphorylation and downstream apoptosis related proteins' activation were also observed in co-culture group after the activation of CXCR7. Moreover, oroxylin A, a bioactive flavonoid isolated from the root of Scutellaria baicalensis Georgi, was found to be effective in reversing BM stroma induced CML resistance to IM. After cells were treated with weakly toxic concentration of oroxylin A, cell apoptosis induced by IM in co-culture model was enhanced. And the activated CXCL12/CXCR7 pathway, the expression of p-ERK and downstream apoptosis related proteins were suppressed. The in vivo study also showed that oroxylin A increased apoptosis of CML cells with low systemic toxicity, and the mechanism was consistent with the in vitro study. In conclusion, oroxylin A improved sensitivity of CML cells to IM treatment in BM microenvironment through regulating CXCL12/CXCR7 pathway. © 2016 Wiley Periodicals, Inc.

Chemokine and chemokine receptors in autoimmunity: the case of primary biliary cholangitis

Chemokines represent a major mediator of innate immunity and play a key role in the selective recruitment of cells during localized inflammatory responses. Beyond critical extracellular mediators of leukocyte trafficking, chemokines and their cognate receptors are expressed by a variety of resident and infiltrating cells (monocytes, lymphocytes, NK cells, mast cells, and NKT cells). Chemokines represent ideal candidates for mechanistic studies (particularly in murine models) to better understand the pathogenesis of chronic inflammation and possibly become biomarkers of disease. Nonetheless, therapeutic approaches targeting chemokines have led to unsatisfactory results in rheumatoid arthritis, while biologics against pro-inflammatory cytokines are being used worldwide with success. In this comprehensive review we will discuss the evidence supporting the involvement of chemokines and their specific receptors in mediating the effector cell response, utilizing the autoimmune/primary biliary cholangitis setting as a paradigm.

Overexpression of neuritin in gastric cancer

The aim of the present study was to investigate the expression of neuritin in gastric cancer tissues, in order to explore the association between the expression of neuritin and the occurrence and development of gastric cancer. Tissue specimens were collected from 58 patients with gastric cancer. Immunohistochemistry, western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine the expression of neuritin in the gastric cancer and corresponding adjacent normal gastric tissues. The expression rate of neuritin in gastric cancer tissues was 96.55% (56/58), demonstrating no statistically significant difference from the expression rate in the adjacent normal tissues (94.83%) (P>0.05). However, the rate of strong neuritin expression in gastric cancer tissues (82.76%) was significantly increased compared with the rate in the adjacent normal tissues (15.52%) (P<0.05). Neuritin expression exhibited no correlation with the gender or age of patients, tumor-node-metastasis staging, tumor depth, presence of lymph node metastasis, histological or pathological type of the tumor or presence of distant metastasis (P>0.05). As determined by RT-PCR and western blot analysis, the mRNA expression of neuritin in gastric cancer tissues was markedly increased compared with the expression in the adjacent normal tissues. In conclusion, neuritin is highly expressed in gastric cancer tissues, suggesting that neuritin may act as a novel potential target for the treatment of gastric cancer.

Role of CXC chemokine receptor type 7 in carcinogenesis and lymph node metastasis of colon cancer

Upregulated expression of the CXC chemokine receptor type 7 (CXCR7) promotes breast, lung and prostate cancer progression and metastasis. However, the role of CXCR7 in colon cancer has not been determined. We hypothesized that increased CXCR7 expression may contribute to human colon cancer occurrence and progression. Reverse transcription quantitative polymerase chain reaction and western blot analysis were performed on 34 malignant and 18 normal colon tissue specimens. The specimens were obtained from 19 male and 15 female patients, with a mean age of 52 years (range, 34-79 years). Of the 34 patients, 20 had lymph node metastases. None of the patients had received adjuvant radiotherapy or chemotherapy prior to surgery. This study demonstrated that CXCR7 levels were significantly higher in colon tumors compared with those in normal colon tissue (P﹤0.01). In addition, lymph node metastatic colon tumors exhibited significantly higher CXCR7 expression compared with non-metastatic tumors (P﹤0.01); however, there were no differences in CXCR7 expression among distinct histopathological types (well-differentiated vs. moderately-to-poorly differentiated adenocarcinoma, P﹥0.01). Therefore, the evidence obtained from the present study supports involvement of the upregulated CXCR7 expression in colon tumorigenesis and lymph node metastasis.

C-X-C motif receptor 7 in gastrointestinal cancer

Chemokine receptors are key mediators of normal physiology and numerous pathological conditions, including inflammation and cancer. This receptor family is an emerging target for anticancer drug development. C-X-C motif receptor 7 (CXCR7) is an atypical chemokine receptor that was first cloned from a canine cDNA library as an orphan receptor and was initially named receptor dog cDNA 1 (RDC1). Shortly after demonstrating that RDC1 binds with its ligand, stromal cell-derived factor-1α and interferon-inducible T-cell α chemoattractant, RDC1 was officially deorphanized and renamed CXCR7, as the seventh receptor in the CXC class of the chemokine receptor family. Recent accumulating evidence has demonstrated that CXCR7 expression is augmented in the majority of tumor cells compared with their normal counterparts and is involved in cell proliferation, survival, migration, invasion and angiogenesis during the initiation and progression of breast, lung and prostate cancer. In the present review, the expression and role of CXCR7, as well as its clinical relevance in cancer of the gastrointestinal system, were investigated. In addition, the potential of this chemokine receptor as a therapeutic target in the treatment of gastrointestinal cancer was discussed.

Propranolol Decreases Proliferation of Endothelial Cells Transformed by Kaposi's Sarcoma-Associated Herpesvirus and Induces Lytic Viral Gene Expression

Kaposi's sarcoma (KS) is common in Africa, but economic constraints hinder successful treatment in most patients. Propranolol, a generic β-adrenergic antagonist, decreased proliferation of KS-associated herpesvirus (KSHV)-infected cells. Downregulation of cyclin A2 and cyclin-dependent kinase 1 (CDK1) recapitulated this phenotype. Additionally, propranolol induced lytic gene expression in association with downregulation of CDK6. Thus, propranolol has diverse effects on KSHV-infected cells, and this generic drug has potential as a therapeutic agent for KS.

Endothelial CXCR7 regulates breast cancer metastasis

Atypical chemokine receptor CXCR7 (ACKR3) functions as a scavenger receptor for chemokine CXCL12, a molecule that promotes multiple steps in tumor growth and metastasis in breast cancer and multiple other malignancies. While normal vascular endothelium expresses low levels of CXCR7, marked upregulation of CXCR7 occurs in tumor vasculature in breast cancer and other tumors. To investigate effects of endothelial CXCR7 in breast cancer, we conditionally deleted this receptor from vascular endothelium of adult mice, generating CXCR7^ΔEND/ΔEND animals. CXCR7^ΔEND/ΔEND mice appeared phenotypically normal, although these animals exhibited a modest 35 ± 3% increase in plasma CXCL12 as compared with control. Using two different syngeneic, orthotopic tumor implant models of breast cancer, we discovered that CXCR7^ΔEND/ΔEND mice had significantly greater local recurrence of cancer following resection, elevated numbers of circulating tumor cells, and more spontaneous metastases. CXCR7^ΔEND/ΔEND mice also showed greater experimental metastases following intracardiac injection of cancer cells. These results establish that endothelial CXCR7 limits breast cancer metastasis at multiple steps in the metastatic cascade, advancing understanding of CXCL12 pathways in tumor environments and informing ongoing drug development targeting CXCR7 in cancer.

Kaposi Sarcoma Herpesvirus Induces HO-1 during De Novo Infection of Endothelial Cells via Viral miRNA-Dependent and -Independent Mechanisms

Kaposi sarcoma (KS) herpesvirus (KSHV) infection of endothelial cells (EC) is associated with strong induction of heme oxygenase-1 (HO-1), a stress-inducible host gene that encodes the rate-limiting enzyme responsible for heme catabolism. KS is an angioproliferative tumor characterized by the proliferation of KSHV-infected spindle cells, and HO-1 is highly expressed in such cells. HO-1 converts the pro-oxidant, proinflammatory heme molecule into metabolites with antioxidant, anti-inflammatory, and proliferative activities. Previously published work has shown that KSHV-infected EC in vitro proliferate in response to free heme in a HO-1-dependent manner, thus implicating virus-enhanced HO-1 activity in KS tumorigenesis. The present study investigated the molecular mechanisms underlying KSHV induction of HO-1 in lymphatic EC (LEC), which are the likely spindle cell precursors. In a time course analysis of KSHV-infected cells, HO-1 expression displays biphasic kinetics characterized by an early transient induction that is followed by a more sustained upregulation coincident with the establishment of viral latency. A viral microRNA miR-K12-11 deletion mutant of KSHV was found to be defective for induction of HO-1 during latency. A potential mechanism for this phenotype was provided by BACH1, a cellular HO-1 transcriptional repressor targeted by miR-K12-11. In fact, in KSHV-infected LEC, the BACH1 message level is reduced, BACH1 subcellular localization is altered, and miR-K12-11 mediates the inverse regulation of HO-1 and BACH1 during viral latency. Interestingly, the data indicate that neither miR-K12-11 nor de novo KSHV gene expression is required for the burst of HO-1 expression observed at early times postinfection, which suggests that additional virion components promote this phenotype.

While the mechanisms underlying KSHV induction of HO-1 remain unknown, the cellular mechanisms that regulate HO-1 expression have been extensively investigated in the context of basal and pathophysiological states. The detoxifying action of HO-1 is critical for the protection of cells exposed to high heme levels. KS spindle cells are erythrophagocytic and contain erythrocyte ghosts. Erythrocyte degeneration leads to the localized release of heme, creating oxidative stress that may be further exacerbated by environmental or other cofactors. Our previous work showed that KSHV-infected cells proliferate in response to heme and that this occurs in a HO-1-dependent manner. We therefore hypothesize that KSHV induction of HO-1 contributes to KS tumor development via heme metabolism and propose that HO-1 be evaluated as a therapeutic target for KS. Our present work, which aimed to understand the mechanisms whereby KSHV induces HO-1, will be important for the design and implementation of such a strategy.

CXCR7 expression disrupts endothelial cell homeostasis and causes ligand-dependent invasion

The homeostatic function of endothelial cells (EC) is critical for a number of physiological processes including vascular integrity, immunity, and wound healing. Indeed, vascular abnormalities resulting from EC dysfunction contribute to the development and spread of malignancies. The alternative SDF-1/CXCL12 receptor CXCR7 is frequently and specifically highly expressed in tumor-associated vessels. In this study, we investigate whether CXCR7 contributes to vascular dysfunction by specifically examining the effect of CXCR7 expression on EC barrier function and motility. We demonstrate that CXCR7 expression in EC results in redistribution of CD31/PECAM-1 and loss of contact inhibition. Moreover, CXCR7+ EC are deficient in barrier formation. We show that CXCR7-mediated motility has no influence on angiogenesis but contributes to another motile process, the invasion of CXCR7+ EC into ligand-rich niches. These results identify CXCR7 as a novel manipulator of EC barrier function via alteration of PECAM-1 homophilic junctions. As such, aberrant expression of CXCR7 in the vasculature has the potential to disrupt vascular homeostasis and could contribute to vascular dysfunction in cancer systems.

Neutral lipid alterations in human herpesvirus 8-infected HUVEC cells and their possible involvement in neo-angiogenesis

Background

Human Herpesvirus 8 (HHV8), the causative agent of Kaposi’s sarcoma, induces an intense modification of lipid metabolism and enhances the angiogenic process in endothelial cells. In the present study, neutral lipid (NL) metabolism and angiogenesis were investigated in HHV8-infected HUVEC cells. The viral replication phases were verified by rtPCR and also by K8.1 and LANA immunostaining.

Results

Lipid droplets (Nile Red) were higher in all phases and NL staining (LipidTOX) combined with viral-antigen detection (immunofluorescence) demonstrated a NL content increase in infected cells. In particular, triglyceride synthesis increases in the lytic phase, whereas cholesteryl ester synthesis rises in the latent one. Moreover, the inhibition of cholesterol esterification reduces neo-tubule formation mainly in latently infected cells.

Conclusions

We suggest that a reprogramming of cholesteryl ester metabolism is involved in regulating neo-angiogenesis in HHV8-infected cells and plays a likely role in the high metastatic potential of derived-tumours.

The Role of Human Herpesvirus 8 in Diabetes Mellitus Type 2: State of the Art and a Medical Hypothesis

Diabetes is a common chronic disease due to an altered glucose metabolism, caused by the quantitative and/or qualitative dysfunction of the insulin hormone. Two types of diabetes are recognized: juvenile diabetes, or type 1, which has an autoimmune origin, and adult diabetes, or type 2 (DMT2), which covers 90-95 % of all diabetic patients.The causes of DMT2 are not yet clear: heredity, life style, nutrition, and environment are considered the main risk factors. Several viral infections, namely cytomegalovirus, coxsackie and other enteroviruses, rubella and hepatitis C virus, have been claimed to be associated with some forms of diabetes. The direct role of viruses as a cause or as a risk of type 1 diabetes has been amply described in several recent reviews. Therefore, this review focuses attention on the role of a human herpes pathogenic virus in the onset of DMT2. By carrying out an analysis of recent literature, we describe the findings reported on an extremely deceitful virus, such as Human Herpes virus 8, and present a medical hypothesis on a possible relationship between this virus and DMT2.

The relevance of the chemokine receptor ACKR3/CXCR7 on CXCL12-mediated effects in cancers with a focus on virus-related cancers

Recent studies have highlighted the importance of understanding the molecular determinants of CXCL12-mediated effects in cancers. Once previously thought to interact exclusively with CXCR4, CXCL12 also binds with high affinity to CXCR7 (recently renamed ACKR3), which belongs to an atypical chemokine receptor family whose members fail to activate Gαi proteins but interact with β-arrestins. In addition to its capacity to control CXCL12 bioavailability, ACKR3 can either enhance or dampen CXCR4-mediated signaling and activity. In light of the most recent findings, we have examined the role of ACKR3 in cancer, including a subset of virus-related cancers.

Site-specific association with host and viral chromatin by Kaposi's sarcoma-associated herpesvirus LANA and its reversal during lytic reactivation

Latency-associated nuclear antigen (LANA), a multifunctional protein expressed by the Kaposi sarcoma-associated herpesvirus (KSHV) in latently infected cells, is required for stable maintenance of the viral episome. This is mediated by two interactions: LANA binds to specific sequences (LBS1 and LBS2) on viral DNA and also engages host histones, tethering the viral genome to host chromosomes in mitosis. LANA has also been suggested to affect host gene expression, but both the mechanism(s) and role of this dysregulation in KSHV biology remain unclear. Here, we have examined LANA interactions with host chromatin on a genome-wide scale using chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq) and show that LANA predominantly targets human genes near their transcriptional start sites (TSSs). These host LANA-binding sites are generally found within transcriptionally active promoters and display striking overrepresentation of a consensus DNA sequence virtually identical to the LANA-binding site 1 (LBS1) motif in KSHV DNA. Comparison of the ChIP-seq profile with whole-transcriptome (high-throughput sequencing of RNA transcripts [RNA-seq]) data reveals that few of the genes that are differentially regulated in latent infection are occupied by LANA at their promoters. This suggests that direct LANA binding to promoters is not the prime determinant of altered host transcription in KSHV-infected cells. Most surprisingly, the association of LANA to both host and viral DNA is strongly disrupted during the lytic cycle of KSHV. This disruption can be prevented by the inhibition of viral DNA synthesis, suggesting the existence of novel and potent regulatory mechanisms linked to either viral DNA replication or late gene expression.

IMPORTANCE

Here, we employ complementary genome-wide analyses to evaluate the distribution of the highly abundant latency-associated nuclear antigen, LANA, on the host genome and its impact on host gene expression during KSHV latent infection. Combined, ChIP-seq and RNA-seq reveal that LANA accumulates at active gene promoters that harbor specific short DNA sequences that are highly reminiscent of its cognate binding sites in the virus genome. Unexpectedly, we found that such association does not lead to remodeling of global host transcription during latency. We also report for the first time that LANA's ability to bind host and viral chromatin is highly dynamic and is disrupted in cells undergoing an extensive lytic reactivation. This therefore suggests that the association of LANA to chromatin during a productive infection cycle is controlled by a new regulatory mechanism.

CXCL12-CXCR7 signaling activates ERK and Akt pathways in human choriocarcinoma cells

Abstract CXCL12 acts as a physiological ligand for the chemokine receptor CXCR7. Chemokine receptor expression by human trophoblast and other placental cells have important implications for understanding the regulation of placental growth and development. We had previously reported the differential expression of CXCR7 in different stages of the human placenta suggesting its possible role in regulation of placental growth and development. In this study, we determined the expression of CXCR7 in human choriocarcinoma JAR cells at the mRNA level and protein level and the downstream signaling pathway mediated by CXCL12-CXCR7 interaction. We observed that binding of CXCL12 to CXCR7 activates the ERK and Akt cell-survival pathways in JAR cells. Inhibition of the ERK and Akt pathways using specific inhibitors (Wortmanin & PD98509) led to the activation of the p38 pathway. Our findings suggest a possible role of CXCR7 in activating the cell survival pathways ERK and Akt in human choriocarcinoma JAR cells.

MicroRNA expression profiles in Kaposi's sarcoma

Kaposi's sarcoma (KS) is a mesenchymal tumor, caused by Human herpesvirus 8 (HHV8) with molecular and cytogenetic changes poorly understood. To gain further insight on the underlying molecular changes in KS, we performed microRNA (miRNA) microarray analysis of 17 Kaposi's sarcoma specimens. Three normal skin specimens were used as controls. The most significant differentially expressed miRNA were confirmed by quantitative reverse transcriptase polymerase chain reaction (RT-PCR). We detected in KS versus normal skin 185 differentially expressed miRNAs, 76 were upregulated and 109 were downregulated. The most significantly downregulated miRNAs were miR-99a, miR-200 family, miR-199b-5p, miR-100 and miR-335, whereas kshv-miR-K12-4-3p, kshv-miR-K12-1, kshv-miR-K12-2, kshv-miR-K12-4-5p and kshv-miR-K12-8 were significantly upregulated. High expression levels of kshv-miR-K12-1 (p = 0.004) and kshv-miR-K12-4-3p (p = 0.001) was confirmed by RT-PCR. The predicted target genes for differentially expressed miRNAs included genes which are involved in a variety of cellular processes such as angiogenesis (i.e. THBS1) and apoptosis (i.e. CASP3, MCL1), suggesting a role for these miRNAs in Kaposi's sarcoma pathogenesis.

Aberrant proliferation in CXCR7+ endothelial cells via degradation of the retinoblastoma protein

Angiogenesis is a critical factor in the growth and dissemination of solid tumors. Indeed, tumor vasculature is abnormal and contributes to the development and spread of malignancies by creating a hostile microenvironment. The alternative SDF-1/CXCL12 receptor, CXCR7, is frequently and specifically expressed in tumor-associated vessels. In this study, we examine the role of endothelium-expressed CXCR7 in tumor vascular dysfunction by specifically examining the contribution of CXCR7 to endothelial cell (EC) proliferation. We demonstrate that CXCR7 expression is sufficient to drive post-confluent growth in EC cultures. Further, we provide a novel mechanism for CXCR7-mediated proliferation via proteasomal degradation of the tumor suppressor protein Rb. These findings identify a heretofore unappreciated role for CXCR7 in vascular dysfunction and confirm this receptor as a plausible target for anti-tumor therapy.

Umbilical cord blood-derived mesenchymal stem cells inhibit, but adipose tissue-derived mesenchymal stem cells promote, glioblastoma multiforme proliferation

Mesenchymal stem cells (MSCs) possess self-renewal and multipotential differentiation abilities, and they are thought to be one of the most reliable stem cell sources for a variety of cell therapies. Recently, cell therapy using MSCs has been studied as a novel therapeutic approach for cancers that show refractory progress and poor prognosis. MSCs from different tissues have different properties. However, the effect of different MSC properties on their application in anticancer therapies has not been thoroughly investigated. In this study, to characterize the anticancer therapeutic application of MSCs from different sources, we established two different kinds of human MSCs: umbilical cord blood-derived MSCs (UCB-MSCs) and adipose-tissue-derived MSCs (AT-MSCs). We used these MSCs in a coculture assay with primary glioblastoma multiforme (GBM) cells to analyze how MSCs from different sources can inhibit GBM growth. We found that UCB-MSCs inhibited GBM growth and caused apoptosis, but AT-MSCs promoted GBM growth. Terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick-end labeling assay clearly demonstrated that UCB-MSCs promoted apoptosis of GBM via tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). TRAIL was expressed more highly by UCB-MSCs than by AT-MSCs. Higher mRNA expression levels of angiogenic factors (vascular endothelial growth factor, angiopoietin 1, platelet-derived growth factor, and insulin-like growth factor) and stromal-derived factor-1 (SDF-1/CXCL12) were observed in AT-MSCs, and highly vascularized tumors were developed when AT-MSCs and GBM were cotransplanted. Importantly, CXCL12 inhibited TRAIL activation of the apoptotic pathway in GBM, suggesting that AT-MSCs may support GBM development in vivo by at least two distinct mechanisms-promoting angiogenesis and inhibiting apoptosis. The opposite effects of AT-MSCs and UCB-MSCs on GBM clearly demonstrate that differences must be considered when choosing a stem cell source for safety in clinical application.

The biochemistry and biology of the atypical chemokine receptors

A subset of chemokine receptors, initially called "silent" on the basis of their apparent failure to activate conventional signalling events, has recently attracted growing interest due to their ability to internalize, degrade, or transport ligands and thus modify gradients and create functional chemokine patterns in tissues. These receptors recognize distinct and complementary sets of ligands with high affinity, are strategically expressed in different cellular contexts, and lack structural determinants supporting Gα(i) activation, a key signalling event in cell migration. This is in keeping with the hypothesis that they have evolved to fulfil fundamentally different functions to the classical signalling chemokine receptors. Based on these considerations, these receptors (D6, Duffy antigen receptor for chemokines (DARC), CCX-CKR1 and CXCR7) are now collectively considered as an emerging class of 'atypical' chemokine receptors. In this article, we review the biochemistry and biology of this emerging chemokine receptor subfamily.

CXCL12 receptor preference, signal transduction, biological response and the expression of 5T4 oncofoetal glycoprotein

CXCL12 is a pleiotropic chemokine capable of eliciting multiple signal transduction cascades and functions, via interaction with either CXCR4 or CXCR7. Factors that determine CXCL12 receptor preference, intracellular signalling route and biological response are poorly understood but are of central importance in the context of therapeutic intervention of the CXCL12 axis in multiple disease states. We have recently demonstrated that 5T4 oncofoetal glycoprotein facilitates functional CXCR4 expression leading to CXCL12 mediated chemotaxis in mouse embryonic cells. Using wild type (WT) and 5T4 knockout (5T4KO) murine embryonic fibroblasts (MEFs), we now show that CXCL12 binding to CXCR4 activates both the ERK and AKT pathways within minutes, but while these pathways are intact, they are non-functional in 5T4KO cells treated with CXCL12. Importantly, in the absence of 5T4 expression, CXCR7 is upregulated and becomes the predominant receptor for CXCL12, activating a distinct signal transduction pathway with slower kinetics involving transactivation of the epidermal growth factor receptor (EGFR), eliciting proliferation rather than chemotaxis. Thus the surface expression of 5T4 marks the use of the CXCR4 rather than the CXCR7 receptor, with distinct consequences for CXCL12 exposure, relevant to the spread and growth of a tumour. Consistent with this hypothesis, we have identified human small cell lung carcinoma cells with similar 5T4/CXCR7 reciprocity that is predictive of biological response to CXCL12 and determined that 5T4 expression is required for functional chemotaxis in these cells.

Role of chemokine receptor CXCR7 in bladder cancer progression

Bladder cancer is one of the most common tumors of the genitourinary tract; however, the molecular events underlying growth and invasion of the tumor remain unclear. Here, role of the CXCR7 receptor in bladder cancer was further explored. CXCR7 protein expression was examined using high-density tissue microarrays. Expression of CXCR7 showed strong epithelial staining that correlated with bladder cancer progression. In vitro and in vivo studies in bladder cancer cell lines suggested that alterations in CXCR7 expression were associated with the activities of proliferation, apoptosis, migration, invasion, angiogenesis and tumor growth. Moreover, CXCR7 expression was able to regulate expression of the proangiogenic factors IL-8 or VEGF, which may involve in the regulation of tumor angiogenesis. Finally, we found that signaling by the CXCR7 in bladder cancer cells activates AKT, ERK and STAT3 pathways. The AKT and ERK pathways may reciprocally regulate, which are responsible for in vitro and in vivo epithelial to mesenchymal transition (EMT) process of bladder cancer. Simultaneously targeting the two pathways by using U0126 and LY294002 inhibitors or using CCX733, a selective CXCR7 antagonist drastically reduced CXCR7-induced EMT process. Taken together, our data show for the first time that CXCR7 plays a role in the development of bladder cancer. Targeting CXCR7 or its downstream-activated AKT and ERK pathways may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for bladder cancer.

Down-regulation of CXCL12 by DNA hypermethylation and its involvement in gastric cancer metastatic progression

BACKGROUND

Chemokine receptors are now known to play an important role in cancer growth and metastasis. However, there is little information regarding chemokine expression in gastric cancer. In this study, we examined CXCL12 expression in gastric cancer and also evaluated whether the down-regulation of CXCL12 is due to aberrant methylation of the gene.

METHODS

CXCL12 expression was examined using real-time reverse-transcription polymerase chain reaction (RT-PCR), immunofluorescence, flow cytometry, and immunohistochemistry, and the methylation status of the gene was evaluated by methylation-specific PCR (MSP) in normal gastric and gastric cancer cell lines and 35 primary gastric carcinomas and corresponding nonmalignant gastric tissues.

RESULTS

The down-regulation of CXCL12 was observed in gastric cancer cell lines and primary gastric carcinomas, while decreased expression of CXCL12 protein was significantly associated with lymph node metastasis and histological grade. And this down-regulation was found to be in accordance with aberrant methylation of the gene. Hypermethylation of the gene was observed in 65.7% (23 of 35) of the primary gastric carcinomas, while it was found in only 11.4% (4/35) of the corresponding nonmalignant tissues. Furthermore, CXCL12 expression was restored in gastric cancer cell lines after treatment with the demethylating agent, 5-aza-2'-deoxycytidine (5-Aza-dC), and demethylation of the highly metastatic cells SGC-7901 induced invasion suppression of the cells. For two CXCL12 receptors, CXCR4 and CXCR7, the mRNA levels remained almost unchanged with the 5-Aza-dC treatment.

CONCLUSIONS

Collectively, our results suggest that the aberrant methylation of CXCL12 frequently occurs in the down-regulation of CXCL12 in gastric cancers and that it may play a role in the metastasis of gastric cancer.

Advanced prostate cancer: reinforcing the strings between inflammation and the metastatic behavior

It is currently estimated that inflammatory responses are linked to 15-20% of all deaths from cancer worldwide. Although many studies point to an important role of inflammation in prostate growth, the contribution of inflammation to castration-resistant prostate cancer is not completely understood. The presence of inflammatory mediators in tumor microenvironment raises the question whether genetic events that participate in cancer development and progression are responsible for the inflammatory milieu inside and surrounding tumors. Activated oncogenes, cytokines, chemokines and their receptors, sustained oxidative stress and antioxidant imbalance share the capacity to orchestrate these pro-inflammatory programs; however, the diversity of the inflammatory cell components will determine the final response in the prostate tissue. These observations give rise to the concept that early genetic events generate an inflammatory microenvironment promoting prostate cancer progression and creating a continuous loop that stimulates a more aggressive stage. It is imperative to dissect the molecular pathologic mechanism of inflammation involved in the generation of the castration-resistant phenotype in prostate cancer. Here, we present a hypothesis where molecular signaling triggered by inflammatory mediators may evolve in prostate cancer progression. Thus, treatment of chronic inflammation may represent an important therapeutic target in advanced prostate cancer.

C-terminal region of EBNA-2 determines the superior transforming ability of type 1 Epstein-Barr virus by enhanced gene regulation of LMP-1 and CXCR7

Type 1 Epstein-Barr virus (EBV) strains immortalize B lymphocytes in vitro much more efficiently than type 2 EBV, a difference previously mapped to the EBNA-2 locus. Here we demonstrate that the greater transforming activity of type 1 EBV correlates with a stronger and more rapid induction of the viral oncogene LMP-1 and the cell gene CXCR7 (which are both required for proliferation of EBV-LCLs) during infection of primary B cells with recombinant viruses. Surprisingly, although the major sequence differences between type 1 and type 2 EBNA-2 lie in N-terminal parts of the protein, the superior ability of type 1 EBNA-2 to induce proliferation of EBV-infected lymphoblasts is mostly determined by the C-terminus of EBNA-2. Substitution of the C-terminus of type 1 EBNA-2 into the type 2 protein is sufficient to confer a type 1 growth phenotype and type 1 expression levels of LMP-1 and CXCR7 in an EREB2.5 cell growth assay. Within this region, the RG, CR7 and TAD domains are the minimum type 1 sequences required. Sequencing the C-terminus of EBNA-2 from additional EBV isolates showed high sequence identity within type 1 isolates or within type 2 isolates, indicating that the functional differences mapped are typical of EBV type sequences. The results indicate that the C-terminus of EBNA-2 accounts for the greater ability of type 1 EBV to promote B cell proliferation, through mechanisms that include higher induction of genes (LMP-1 and CXCR7) required for proliferation and survival of EBV-LCLs.

Epstein-Barr virus (EBV) is a common human virus that is involved in several types of cancer and directly causes human B lymphocytes to proliferate when they become infected. EBV occurs naturally as two different viral types (type 1 and type 2). The genomes of these viruses are mostly very similar but they differ in a few genes, particularly the EBNA-2 gene. For many years it has been known that type 1 EBV is much more effective than type 2 EBV at causing B lymphocyte proliferation and this difference is mediated by the EBNA-2 gene. Here we have shown that the greater ability of type 1 EBNA-2 to cause B cell proliferation is due to superior induction of the EBV LMP-1 and the cell CXCR7 genes, both of which are required for growth of EBV-infected lymphocytes. We mapped the section of type 1 EBNA-2 responsible for this to the C-terminus of the protein, including the transactivation and EBNA-LP interaction domains. The results provide a mechanism for the long-standing question of the functional difference between these two major types of EBV and will be important in understanding the significance of the EBV types in human infection.