CXCL12 expression is predictive of a shorter time to tumor progression in low-grade glioma: a single-institution study in 50 patients

Relationship between chemokine/chemokine receptor and glioma prognosis and outcomes: Systematic review and meta-analysis

BACKGROUND

Glioma is a primary tumor originating from the central nervous system, and despite ongoing efforts to improve treatment, its overall survival rate remains low. There are a limited number of reports regarding the clinical grading, prognostic impact, and utility of chemokines. Therefore, conducting a meta-analysis is necessary to obtain convincing and conclusive results.

METHODS

A comprehensive literature search was conducted using various databases, including PubMed, Web of Science, The Cochrane Library, Embase, Ovid Medline, CNKI, Wanfang Database, VIP, and CBM. The search encompassed articles published from the inception of the databases until March 2024. The estimated odds ratio (ORs), standard mean difference (SMDs), and hazard ratio (HR) with their corresponding 95% confidence intervals (95% CI) were calculated to assess the predictive value of chemokine and receptor levels in glioma risk. Additionally, heterogeneity tests and bias tests were performed to evaluate the reliability of the findings.

RESULTS

This meta-analysis included a total of 36 studies, involving 2,480 patients diagnosed with glioma. The results revealed a significant association between the expression levels of CXCR4 (n = 8; OR = 22.28; 95 % CI = 11.47-43.30; p = 0.000), CXCL12 (n = 4; OR = 10.69; 95 % CI = 7.03-16.24; p = 0.000), CCL2 (n = 6; SMD = -0.83; 95 % CI = -0.98--0.67; p = 0.000), CXCL8 (n = 3; SMD = 0.75; 95 % CI = 0.47-1.04; p = 0.000), CXCR7 (n = 3; OR = 20.66; 95 % CI = 10.20-41.82; p = 0.000), CXCL10 (n = 2; SMD = 3.27; 95 % CI = 2.91-3.62; p = 0.000) and the risk of glioma. Additionally, a significant correlation was observed between CXCR4 (n = 8; OR = 4.39; 95 % CI = 3.04-6.32; p = 0.000), (n = 6; SMD = 1.37; 95 % CI = 1.09-1.65; p = 0.000), CXCL12 (n = 6; OR = 6.30; 95 % CI = 3.87-10.25; p = 0.000), (n = 5; ES = 2.25; 95 % CI = 1.15-3.34; p = 0.041), CCL2 (n = 3; OR = 9.65; 95 % CI = 4.55-20.45; p = 0.000), (n = 4; SMD = -1.47; 95 % CI = -1.68--1.26; p = 0.000), and CCL18 (n = 3; SMD = 1.62; 95 % CI = 1.30-1.93; p = 0.000) expression levels and high-grade glioma (grades 3-4). Furthermore, CXCR4 (HR = 2.38, 95 % CI = 1.66-3.40; p = 0.000) exhibited a strong correlation with poor overall survival (OS) rates in glioma patients.

CONCLUSION

The findings of this study showed a robust association between elevated levels of CXCR4, CXCL12, CCL2, CXCL8, CXCL10 and CXCR7 with a higher risk of glioma. Furthermore, the WHO grading system was validated by the strong correlation shown between higher expression of CXCR4, CXCL12, CCL2, and CCL18 and WHO high-grade gliomas (grades 3-4). Furthermore, the results of the meta-analysis suggested that CXCR4 might be a helpful biomarker for predicting the worse prognosis of glioma patients.

Non-neoplastic astrocytes: key players for brain tumor progression

Astrocytes are highly plastic cells whose activity is essential to maintain the cerebral homeostasis, regulating synaptogenesis and synaptic transmission, vascular and metabolic functions, ions, neuro- and gliotransmitters concentrations. In pathological conditions, astrocytes may undergo transient or long-lasting molecular and functional changes that contribute to disease resolution or exacerbation. In recent years, many studies demonstrated that non-neoplastic astrocytes are key cells of the tumor microenvironment that contribute to the pathogenesis of glioblastoma, the most common primary malignant brain tumor and of secondary metastatic brain tumors. This Mini Review covers the recent development of research on non-neoplastic astrocytes as tumor-modulators. Their double-edged capability to promote cancer progression or to represent potential tools to counteract brain tumors will be discussed.

Nanobody-based retargeting of an oncolytic herpesvirus for eliminating CXCR4+ GBM cells: A proof of principle

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, which remains difficult to cure. The very high recurrence rate has been partly attributed to the presence of GBM stem-like cells (GSCs) within the tumors, which have been associated with elevated chemokine receptor 4 (CXCR4) expression. CXCR4 is frequently overexpressed in cancer tissues, including GBM, and usually correlates with a poor prognosis. We have created a CXCR4-retargeted oncolytic herpesvirus (oHSV) by insertion of an anti-human CXCR4 nanobody in glycoprotein D of an attenuated HSV-1 (ΔICP34.5, ΔICP6, and ΔICP47), thereby describing a proof of principle for the use of nanobodies to target oHSVs toward specific cellular entities. Moreover, this virus has been armed with a transgene expressing a soluble form of TRAIL to trigger apoptosis. In vitro, this oHSV infects U87MG CXCR4⁺ and patient-derived GSCs in a CXCR4-dependent manner and, when armed, triggers apoptosis. In a U87MG CXCR4⁺ orthotopic xenograft mouse model, this oHSV slows down tumor growth and significantly improves mice survival. Customizing oHSVs with diverse nanobodies for targeting multiple proteins appears as an interesting approach for tackling the heterogeneity of GBM, especially GSCs. Altogether, our study must be considered as a proof of principle and a first step toward personalized GBM virotherapies to complement current treatments.

The CXCL Family Contributes to Immunosuppressive Microenvironment in Gliomas and Assists in Gliomas Chemotherapy

Gliomas are a type of malignant central nervous system tumor with poor prognosis. Molecular biomarkers of gliomas can predict glioma patient's clinical outcome, but their limitations are also emerging. C-X-C motif chemokine ligand family plays a critical role in shaping tumor immune landscape and modulating tumor progression, but its role in gliomas is elusive. In this work, samples of TCGA were treated as the training cohort, and as for validation cohort, two CGGA datasets, four datasets from GEO database, and our own clinical samples were enrolled. Consensus clustering analysis was first introduced to classify samples based on CXCL expression profile, and the support vector machine was applied to construct the cluster model in validation cohort based on training cohort. Next, the elastic net analysis was applied to calculate the risk score of each sample based on CXCL expression. High-risk samples associated with more malignant clinical features, worse survival outcome, and more complicated immune landscape than low-risk samples. Besides, higher immune checkpoint gene expression was also noticed in high-risk samples, suggesting CXCL may participate in tumor evasion from immune surveillance. Notably, high-risk samples also manifested higher chemotherapy resistance than low-risk samples. Therefore, we predicted potential compounds that target high-risk samples. Two novel drugs, LCL-161 and ADZ5582, were firstly identified as gliomas' potential compounds, and five compounds from PubChem database were filtered out. Taken together, we constructed a prognostic model based on CXCL expression, and predicted that CXCL may affect tumor progression by modulating tumor immune landscape and tumor immune escape. Novel potential compounds were also proposed, which may improve malignant glioma prognosis.

Study on the Prognostic Values of Dynactin Genes in Low-Grade Glioma

OBJECTIVE

This present study aims to investigate the potential prognostic values of dynactin genes (DCTN) for predicting the overall survival (OS) in low-grade glioma (LGG) patients.

METHODS

The DCTN mRNA expression data were downloaded from The Cancer Genome Atlas database containing 518 patients with LGG. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses for DCTN genes were performed by using Database for Annotation, Visualization, and Integrated Discovery platform, and their enrichment results were verified by using the Biological Networks Gene Ontology tool. Next, the correlations between DCTN genes and LGG were identified by Pearson correlation coefficient analysis. The OS was estimated by Kaplan-Meier survival analysis. The cBio Cancer Genomics Portal was used to analyze the mutations of DCTN genes and their effects on the prognosis of LGG. The correlation between the abundance of immune infiltration and tumor purity of DCTN genes were predicted by The Tumor Immune Estimation Resource.

RESULTS

Our research showed that the mRNA expression of DCTN4 in tumor tissues was much higher (P < 0.01) than that in normal tissues. Meanwhile, there was a certain correlation between the DCTN genes. Survival analysis showed that the high expression of DCTN1, DCTN3, DCTN4, DCTN6, and their co-expression were significantly correlated with favorable OS in LGG patients (P < 0.05). In DCTN2, a high mutation rate was observed. Further research showed that the genetic alteration in DCTN genes was related to a poor OS and progression-free survival of LGG patients. The expression of DCTN genes had a certain correlation with immune infiltrating cells.

CONCLUSION

Our study showed that the high expressions of DCTN1, DCTN3, DCTN4, and DCTN6 were associated with a favorable OS of LGG patients, indicating that these DCTN genes are potential biomarkers for evaluating the prognosis of LGG patients.

The Role of Selected Chemokines and Their Receptors in the Development of Gliomas

Among heterogeneous primary tumors of the central nervous system (CNS), gliomas are the most frequent type, with glioblastoma multiforme (GBM) characterized with the worst prognosis. In their development, certain chemokine/receptor axes play important roles and promote proliferation, survival, metastasis, and neoangiogenesis. However, little is known about the significance of atypical receptors for chemokines (ACKRs) in these tumors. The objective of the study was to present the role of chemokines and their conventional and atypical receptors in CNS tumors. Therefore, we performed a thorough search for literature concerning our investigation via the PubMed database. We describe biological functions of chemokines/chemokine receptors from various groups and their significance in carcinogenesis, cancer-related inflammation, neo-angiogenesis, tumor growth, and metastasis. Furthermore, we discuss the role of chemokines in glioma development, with particular regard to their function in the transition from low-grade to high-grade tumors and angiogenic switch. We also depict various chemokine/receptor axes, such as CXCL8-CXCR1/2, CXCL12-CXCR4, CXCL16-CXCR6, CX3CL1-CX3CR1, CCL2-CCR2, and CCL5-CCR5 of special importance in gliomas, as well as atypical chemokine receptors ACKR1-4, CCRL2, and PITPMN3. Additionally, the diagnostic significance and usefulness of the measurement of some chemokines and their receptors in the blood and cerebrospinal fluid (CSF) of glioma patients is also presented.

Tumor Angiogenic Inhibition Triggered Necrosis (TAITN) in Oral Cancer

CXCR4 is a chemokine receptor crucial in tumor progression, although the angiogenic role of CXCR4 in oral squamous cell carcinoma (OSCC) has not been investigated. Here we show that CXCR4 is crucial for tumor angiogenesis, thereby supporting tumor survival in OSCC. Immunohistochemistry on human clinical specimens revealed that CXCR4 and a tumor vasculature marker CD34 were co-distributed in tumor vessels in human OSCC specimens. To uncover the effects of CXCR4 inhibition, we treated the OSCC-xenografted mice with AMD3100, so-called plerixafor, an antagonist of CXCR4. Notably, we found a unique pathophysiological structure defined as tumor angiogenic inhibition triggered necrosis (TAITN), which was induced by the CXCR4 antagonism. Treatment with AMD3100 increased necrotic areas with the induction of hypoxia-inducible factor-1α in the xenografted tumors, suggesting that AMD3100-induced TAITN was involved in hypoxia and ischemia. Taken together, we demonstrated that CXCR4 plays a crucial role in tumor angiogenesis required for OSCC progression, whereas TAITN induced by CXCR4 antagonism could be an effective anti-angiogenic therapeutic strategy in OSCC treatment.

Targeting the Post-Irradiation Tumor Microenvironment in Glioblastoma via Inhibition of CXCL12

Radiotherapy is a mainstay in glioblastoma therapy as it not only directly targets tumor cells but also depletes the tumor microvasculature. The resulting intra-tumoral hypoxia initiates a chain of events that ultimately leads to re-vascularization, immunosuppression and, ultimately, tumor-regrowth. The key component of this cascade is overexpression of the CXC-motive chemokine ligand 12 (CXCL12), formerly known as stromal-cell derived factor 1 (SDF-1). We here review the role of CXCL12 in recruitment of pro-vasculogenic and immunosuppressive cells and give an overview on future and current drugs that target this axis.

Potential Role of CXCR4 Targeting in the Context of Radiotherapy and Immunotherapy of Cancer

Cancer immunotherapy has been established as standard of care in different tumor entities. After the first reports on synergistic effects with radiotherapy and the induction of abscopal effects-tumor shrinkage outside the irradiated volume attributed to immunological effects of radiotherapy-several treatment combinations have been evaluated. Different immunotherapy strategies (e.g., immune checkpoint inhibition, vaccination, cytokine based therapies) have been combined with local tumor irradiation in preclinical models. Clinical trials are ongoing in different cancer entities with a broad range of immunotherapeutics and radiation schedules. SDF-1 (CXCL12)/CXCR4 signaling has been described to play a major role in tumor biology, especially in hypoxia adaptation, metastasis and migration. Local tumor irradiation is a known inducer of SDF-1 expression and release. CXCR4 also plays a major role in immunological processes. CXCR4 antagonists have been approved for the use of hematopoietic stem cell mobilization from the bone marrow. In addition, several groups reported an influence of the SDF-1/CXCR4 axis on intratumoral immune cell subsets and anti-tumor immune response. The aim of this review is to merge the knowledge on the role of SDF-1/CXCR4 in tumor biology, radiotherapy and immunotherapy of cancer and in combinatorial approaches.

Engineering NK Cells Modified With an EGFRvIII-specific Chimeric Antigen Receptor to Overexpress CXCR4 Improves Immunotherapy of CXCL12/SDF-1α-secreting Glioblastoma

Natural killer (NK) cells are promising effector cells for adjuvant immunotherapy of cancer. So far, several preclinical studies have shown the feasibility of gene-engineered NK cells, which upon expression of chimeric antigen receptors (CARs) are redirected to otherwise NK cell-resistant tumors. Yet, we reasoned that the efficiency of an immunotherapy using CAR-modified NK cells critically relies on efficient migration to the tumor site and might be improved by the engraftment of a receptor specific for a chemokine released by the tumor. On the basis of the DNAX-activation protein 12 (DAP12), a signaling adapter molecule involved in signal transduction of activating NK cell receptors, we constructed an epidermal growth factor variant III (EGFRvIII)-CAR, designated MR1.1-DAP12 which confers specific cytotoxicity of NK cell towards EGFRvIII glioblastoma cells in vitro and to established subcutaneous U87-MG tumor xenografts. So far, infusion of NK cells with expression of MR1.1-DAP12 caused a moderate but significantly delayed tumor growth and increased median survival time when compared with NK cells transduced with an ITAM-defective CAR. Notably, the further genetic engineering of these EGFRvIII-specific NK cells with the chemokine receptor CXCR4 conferred a specific chemotaxis to CXCL12/SDF-1α secreting U87-MG glioblastoma cells. Moreover, the administration of such NK cells resulted in complete tumor remission in a number of mice and a significantly increased survival when compared with the treatment of xenografts with NK cells expressing only the EGFRvIII-specific CAR or mock control. We conclude that chemokine receptor-engineered NK cells with concomitant expression of a tumor-specific CAR are a promising tool to improve adoptive tumor immunotherapy.

Cytokine Regulation of Metastasis and Tumorigenicity

The human body combats infection and promotes wound healing through the remarkable process of inflammation. Inflammation is characterized by the recruitment of stromal cell activity including recruitment of immune cells and induction of angiogenesis. These cellular processes are regulated by a class of soluble molecules called cytokines. Based on function, cell target, and structure, cytokines are subdivided into several classes including: interleukins, chemokines, and lymphokines. While cytokines regulate normal physiological processes, chronic deregulation of cytokine expression and activity contributes to cancer in many ways. Gene polymorphisms of all types of cytokines are associated with risk of disease development. Deregulation RNA and protein expression of interleukins, chemokines, and lymphokines have been detected in many solid tumors and hematopoetic malignancies, correlating with poor patient prognosis. The current body of literature suggests that in some tumor types, interleukins and chemokines work against the human body by signaling to cancer cells and remodeling the local microenvironment to support the growth, survival, and invasion of primary tumors and enhance metastatic colonization. Some lymphokines are downregulated to suppress tumor progression by enhancing cytotoxic T cell activity and inhibiting tumor cell survival. In this review, we will describe the structure/function of several cytokine families and review our current understanding on the roles and mechanisms of cytokines in tumor progression. In addition, we will also discuss strategies for exploiting the expression and activity of cytokines in therapeutic intervention.

SDF-1α may be an independent risk factor for lymph node metastasis in gastric cancer

AIM: To explore the relationship between the expression of stromal cell-derived factor-1α (SDF-1α) and lymph node metastasis in gastric cancer patients.

METHODS: The expression of SDF-1α in gastric cancer tissues from 152 patients was detected by immunohistochemistry. The correlations of SDF-1α with clinicopathologic features were analyzed.

RESULTS: SDF-1α expression was significantly correlated with tumor lymphatic vessel invasion (P = 0.016) and lymph node metastasis (P = 0.003), but not with patients age, gender, tumor size, gross type, depth of invasion or degree of differentiation (P = 0.003). Undifferentiated histology (HR = 3.312; 95%CI: 1.414-7.825, P = 0.008), lymphatic vessel invasion (HR = 11.215; 95%CI: 2.780-45.978, P = 0.002) and SDF-1α expression (HR = 3.194; 95%CI: 1.313-7.296, P = 0.013) were identified to be risk factors for gastric cancer. Undifferentiated histology (HR = 3.054; 95%CI: 1.176-8.614, P = 0.039), lymphatic vessel invasion (HR = 8.651; 95%CI: 1.731-44.959, P = 0.008) and SDF-1α expression (HR = 2.219; 95%CI: 1.327-10.346, P = 0.015) were also identified to be independent risk factors for lymph node metastasis in gastric cancer patients.

CONCLUSION: SDF-1α may be an independent risk factor for lymph node metastasis in gastric cancer.

CXCL12 modulation of CXCR4 and CXCR7 activity in human glioblastoma stem-like cells and regulation of the tumor microenvironment

Chemokines are crucial autocrine and paracrine players in tumor development. In particular, CXCL12, through its receptors CXCR4 and CXCR7, affects tumor progression by controlling cancer cell survival, proliferation and migration, and, indirectly, via angiogenesis or recruiting immune cells. Glioblastoma (GBM) is the most prevalent primary malignant brain tumor in adults and despite current multimodal therapies it remains almost incurable. The aggressive and recurrent phenotype of GBM is ascribed to high growth rate, invasiveness to normal brain, marked angiogenesis, ability to escape the immune system and resistance to standard of care therapies. Tumor molecular and cellular heterogeneity severely hinders GBM therapeutic improvement. In particular, a subpopulation of chemo- and radio-therapy resistant tumorigenic cancer stem-like cells (CSCs) is believed to be the main responsible for tumor cell dissemination to the brain. GBM cells display heterogeneous expression levels of CXCR4 and CXCR7 that are overexpressed in CSCs, representing a molecular correlate for the invasive potential of GBM. The microenvironment contribution in GBM development is increasingly emphasized. An interplay exists between CSCs, differentiated GBM cells, and the microenvironment, mainly through secreted chemokines (e.g., CXCL12) causing recruitment of fibroblasts, endothelial, mesenchymal and inflammatory cells to the tumor, via specific receptors such as CXCR4. This review covers recent developments on the role of CXCL12/CXCR4-CXCR7 networks in GBM progression and the potential translational impact of their targeting. The biological and molecular understanding of the heterogeneous GBM cell behavior, phenotype and signaling is still limited. Progress in the identification of chemokine-dependent mechanisms that affect GBM cell survival, trafficking and chemo-attractive functions, opens new perspectives for development of more specific therapeutic approaches that include chemokine-based drugs.

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.

Glioma cell migration and invasion as potential target for novel treatment strategies

Diffuse human gliomas constitute a group of most treatment-refractory tumors even if maximum treatment strategies including neurosurgical resection followed by combined radio-/chemotherapy are applied. In contrast to most other neoplasms, diffusely infiltrating gliomas invade the brain along pre-existing structures such as axonal tracts and perivascular spaces. Even in cases of early diagnosis single or small clusters of glioma cells are already encountered far away from the main tumor bulk. Complex interactions between glioma cells and the surrounding extracellular matrix and considerable changes in the cytoskeletal apparatus are prerequisites for the cellular movement of glioma cells through the brain thereby escaping from most current treatments. This review provides an overview about classical and current concepts of glioma cell migration/invasion and promising preclinical treatment approaches.

Interstitial flow in a 3D microenvironment increases glioma invasion by a CXCR4-dependent mechanism

Brain tumor invasion leads to recurrence and resistance to treatment. Glioma cells invade in distinct patterns, possibly determined by microenvironmental cues including chemokines, structural heterogeneity, and fluid flow. We hypothesized that flow originating from pressure differentials between the brain and tumor is active in glioma invasion. Using in vitro models, we show that interstitial flow promotes cell invasion in multiple glioma cell lines. Flow effects were CXCR4-dependent, because they were abrogated by CXCR4 inhibition. Furthermore, CXCR4 was activated in response to flow, which could be responsible for enhanced cell motility. Flow was seen to enhance cell polarization in the flow direction, and this flow-induced polarization could be blocked by CXCR4 inhibition or CXCL12 oversaturation in the matrix. Furthermore, using live imaging techniques in a three-dimensional flow chamber, there were more cells migrating and more cells migrating in the direction of flow. This study shows that interstitial flow is an active regulator of glioma invasion. The new mechanisms of glioma invasion that we identify here-namely, interstitial flow-enhanced motility, activation of CXCR4, and CXCL12-driven autologous chemotaxis-are significant in therapy to prevent or treat brain cancer invasion. Current treatment strategies can lead to edema and altered flow in the brain, and one popular experimental treatment in clinical trials, convection enhanced delivery, involves enhancement of flow in and around the tumor. A better understanding of how interstitial flow at the tumor margin can alter chemokine distributions, cell motility, and directed invasion offers a better understanding of treatment failure. .

Expression and Role of the Intermediate-Conductance Calcium-Activated Potassium Channel KCa3.1 in Glioblastoma

Glioblastomas are characterized by altered expression of several ion channels that have important consequences in cell functions associated with their aggressiveness, such as cell survival, proliferation, and migration. Data on the altered expression and function of the intermediate-conductance calcium-activated K (KCa3.1) channels in glioblastoma cells have only recently become available. This paper aims to (i) illustrate the main structural, biophysical, pharmacological, and modulatory properties of the KCa3.1 channel, (ii) provide a detailed account of data on the expression of this channel in glioblastoma cells, as compared to normal brain tissue, and (iii) critically discuss its major functional roles. Available data suggest that KCa3.1 channels (i) are highly expressed in glioblastoma cells but only scantly in the normal brain parenchima, (ii) play an important role in the control of glioblastoma cell migration. Altogether, these data suggest KCa3.1 channels as potential candidates for a targeted therapy against this tumor.

Chemokine (C-X-C motif) ligand 12 is associated with gallbladder carcinoma progression and is a novel independent poor prognostic factor

PURPOSE

Although recent studies have suggested that chemokine (C-X-C motif) ligand 12 (CXCL12) is important in the progression of various malignancies, its role in gallbladder carcinoma (GBC) remains unknown. We investigated CXCL12 expression in GBC and its biologic and prognostic role in GBC tumorigenesis.

EXPERIMENTAL DESIGN

We examined CXCL12 expression in tumor specimens from 72 patients with GBC by immunohistochemistry and analyzed the correlation between CXCL12 expression and clinicopathologic factors or survival. The functional significance of CXCL12 expression was investigated by CXCL12 treatment and suppression of CXCR4, a major receptor of CXCL12, as well as by CXCL12 overexpression in in vitro and in vivo studies.

RESULTS

CXCL12 was differentially expressed in GBC tissues. CXCL12 expression was significantly associated with a high histologic grade (P = 0.042) and nodal metastasis (P = 0.015). Multivariate analyses showed that CXCL12 expression (HR, 8.675; P = 0.014) was an independent risk factor for patient survival. CXCL12 significantly increased anchorage-dependent and -independent growth, migration, invasion, adhesiveness, and survival of GBC cells in vitro, and these effects were dependent on CXCR4. Consistent with these results, overexpression of CXCL12 significantly promoted GBC tumorigenicity in a xenograft model.

CONCLUSIONS

Our results indicate that GBC cells express both CXCL12 and its receptor CXCR4, and CXCL12 may have a role in GBC progression through an autocrine mechanism. In addition, CXCL12 is a novel independent poor prognostic factor in patients with GBCs. Thus, targeting CXCL12 and CXCR4 may provide a novel therapeutic strategy for GBC treatment.

Stromal-cell-derived Factor 1-α Promotes Tumor Progression in Colorectal Cancer

PURPOSE

Although stromal-cell-derived factor (SDF)-1α is suggested to be involved in tumorigenicity and tumor angiogenesis, the clinicopathological significance of its expression in colorectal cancers is not fully understood. We examined SDF-1α expression in colorectal cancers and investigated its relationship to clinicopathological features such as tumor staging, lymph-node metastasis, vascular invasion (VI), lymphatic invasion (LI) and neural invasion (NI).

METHODS

Specimens of 83 primary colorectal cancers were examined immunohistochemically, and the relationships between clinicopathological features and SDF-1α expression were analyzed. To compare the expressions between the normal colon tissue and colorectal cancer tissues, we performed Western blot analyses.

RESULTS

According to the Western blot analyses, SDF-1α was more highly expressed in colorectal carcinoma tissues than in normal colonic mucosa (20/21). According to the immunohistochemical stain, SDF-1α was associated with nodal status, distant metastasis, tumor staging, VI and LI. SDF-1α expression had a significant prognostic value for overall survival. Kaplan-Meier plots of survival in patients with high SDF-1α showed that high SDF-1α expression was associated with a shorter overall survival. However, no association was found between SDF-1α expression and other pathologic or clinical variables, including age, gender, degree of differentiation, and presence of perineural invasion.

CONCLUSION

The expression of SDF-1α might be associated with tumor progression in colorectal cancer. Inhibition of SDF-1α could be a therapeutic option in colorectal cancer patients.

Suppression of G-protein-coupled receptor kinase 3 expression is a feature of classical GBM that is required for maximal growth

G-protein-coupled receptor kinases (GRK) regulate the function of G-protein-coupled receptors (GPCR). Previously, we found that GPCR (CXCR4)-mediated astrocytoma growth was dependent upon abnormally sustained CXCR4 signaling and was correlated with decreased GRK-mediated receptor phosphorylation. As CXCR4 has also been implicated in the stimulation of high-grade glioma growth, we sought to determine whether dysregulation of GRK expression and/or function might also be present in high-grade gliomas. In an analysis of data from The Cancer Genome Atlas, we found that GRK3 expression is frequently decreased in glioblastoma (GBM) of the classical subtype, which possesses signature amplification or mutational activation of the epidermal growth factor (EGF) receptor. We tested the correlation between GRK3 expression and GBM subtypes, as well as the relationship between the activation of the EGF and other growth factor receptor pathways and GRK expression. In analyses of primary GBM tissue and RNA specimens, we found that GRK3 expression is correlated with established criteria for GBM subtyping including expression of EGF receptor, platelet-derived growth factor receptor (PDGFR)α, NF1, PTEN, CDKN2A, and neurofilament. We also found that established drivers of gliomagenesis, the EGF, PDGF, and TGF-β pathways, all regulate GRK expression. Coculture experiments, designed to mimic critical interactions between tumor and brain microvascular endothelial cells, showed that specifically increasing GRK3 expression reduced the trophic effect of endothelial cells on tumor cells. Together, these experiments show that GRK3 is a negative regulator of cell growth whose expression is preferentially reduced in GBM of the classical subtype as a consequence of activity in primary gliomagenic pathways.

Expression of stromal cell-derived factor-1α is an independent risk factor for lymph node metastasis in early gastric cancer

Lymph node metastasis is considered to be a significant prognostic factor for early gastric cancer (EGC). However, no real consensus exists on which patient and/or tumor characteristics are associated with lymph node metastasis. We investigated whether stromal cell-derived factor (SDF)-1α expression correlates with lymph node metastasis in patients with EGC by immunohistochemically examining the expression of SDF-1α in 138 archival tissue specimens of EGC. Of these specimens, 59 (42.8%) and 79 (57.2%) were grouped into SDF-1α-positive and SDF-1α-negative groups, respectively. No significant differences existed with respect to age, gender, tumor location, proportion of tumors >20 mm in size, macroscopic type, depth of invasion or histology between the SDF-1α-positive and -negative groups. However, the SDF-1α-positive group was significantly correlated with lymphovascular invasion and lymph node metastasis. Results of the univariate analyses indicated that lymphovascular invasion, undifferentiated histology and SDF-1α positivity were statistically significant risk factors affecting lymph node metastasis in patients with EGC. Multivariate analyses showed that lymphovascular invasion [hazard ratio (HR), 8.595; 95% confidence interval (CI), 1.694-43.595; P=0.009], undifferentiated histology (HR, 2.965; 95% CI, 1.037-8.471; P=0.043) and SDF-1α positivity (HR, 2.108; 95% CI, 1.316-10.135; P=0.013) were independent risk factors predicting lymph node metastasis in EGC. In conclusion, these results suggest that SDF-1α expression in tumor cells is a predictive marker of lymph node metastasis in EGC.

CXCL12-induced glioblastoma cell migration requires intermediate conductance Ca2+-activated K+ channel activity

The activation of ion channels is crucial during cell movement, including glioblastoma cell invasion in the brain parenchyma. In this context, we describe for the first time the contribution of intermediate conductance Ca2+-activated K (IKCa) channel activity in the chemotactic response of human glioblastoma cell lines, primary cultures, and freshly dissociated tissues to CXC chemokine ligand 12 (CXCL12), a chemokine whose expression in glioblastoma has been correlated with its invasive capacity. We show that blockade of the IKCa channel with its specific inhibitor 1-[(2-chlorophenyl) diphenylmethyl]-1 H-pyrazole (TRAM-34) or IKCa channel silencing by short hairpin RNA (shRNA) completely abolished CXCL12-induced cell migration. We further demonstrate that this is not a general mechanism in glioblastoma cell migration since epidermal growth factor (EGF), which also activates IKCa channels in the glioblastoma-derived cell line GL15, stimulate cell chemotaxis even if the IKCa channels have been blocked or silenced. Furthermore, we demonstrate that both CXCL12 and EGF induce Ca2+ mobilization and IKCa channel activation but only CXCL12 induces a long-term upregulation of the IKCa channel activity. Furthermore, the Ca2+-chelating agent BAPTA-AM abolished the CXCL12-induced, but not the EGF-induced, glioblastoma cell chemotaxis. In addition, we demonstrate that the extracellular signal-regulated kinase (ERK)1/2 pathway is only partially implicated in the modulation of CXCL12-induced glioblastoma cell movement, whereas the phosphoinositol-3 kinase (PI3K) pathway is not involved. In contrast, EGF-induced glioblastoma migration requires both ERK1/2 and PI3K activity. All together these findings suggest that the efficacy of glioblastoma invasiveness might be related to an array of nonoverlapping mechanisms activated by different chemotactic agents.

Expression pattern of stromal cell-derived factor-1 chemokine in invasive breast cancer is correlated with estrogen receptor status and patient prognosis

Chemokine receptor CXCR4 is known to be crucially involved in tumor progression, but the role of its ligand, stromal cell-derived factor-1 (SDF-1), remains unclear. The present study was conducted to clarify the clinicopathological and prognostic impact of SDF-1 expression in invasive breast cancers. Expression of SDF-1 mRNA and protein was examined in five breast cancer cell lines with or without estradiol treatment. In 52 surgically resected breast cancers, the level of SDF-1 mRNA in frozen samples and the pattern of SDF-1 protein immunoreactivity in formalin-fixed paraffin-embedded tissue sections were compared. In another cohort of 223 breast cancers, the correlation between SDF-1 immunoreactivity and clinicopathological parameters was examined using a tissue microarray. Estradiol treatment markedly increased the expression of SDF-1 mRNA and protein in the estrogen receptor (ER)-positive cell lines, MCF-7 and T47D. Among the 52 resected breast cancers, those with a cytoplasmic-dominant pattern of SDF-1 expression showed higher SDF-1 mRNA levels (median 27.4) than those with a membrane-dominant or negative pattern (median 13.6, P = 0.0017). Accordingly, the cytoplasmic-dominant pattern was defined as "high SDF-1 expression," and other patterns were defined as "low SDF-1 expression." Among the cohort of 223 tumors, "high SDF-1 expression" was detected in 158 (70.9%) and was significantly correlated with ER positivity (P < 0.0001), HER2 negativity (P = 0.021), and lower grade (P < 0.0001). Univariate analysis demonstrated that "high SDF-1 expression" was a significant indicator of better clinical outcome in both the entire patient cohort (P = 0.017) and the 133 patients with ER-positive tumors (P = 0.036), but not in the 90 patients with ER-negative tumors. Multivariate analysis showed that SDF-1 status was an independent factor related to overall survival in patients with ER-positive tumors (P = 0.046). SDF-1 status is a significant prognostic factor and may be clinically useful for assigning adjuvant therapy to patients with ER-positive invasive breast cancers.

Role of chemokine network in the development and progression of ovarian cancer: a potential novel pharmacological target

Ovarian cancer is the most common type of gynecologic malignancy. Despite advances in surgery and chemotherapy, the survival rate is still low since most ovarian cancers relapse and become drug-resistant. Chemokines are small chemoattractant peptides mainly involved in the immune responses. More recently, chemokines were also demonstrated to regulate extra-immunological functions. It was shown that the chemokine network plays crucial functions in the tumorigenesis in several tissues. In particular the imbalanced or aberrant expression of CXCL12 and its receptor CXCR4 strongly affects cancer cell proliferation, recruitment of immunosuppressive cells, neovascularization, and metastasization. In the last years, several molecules able to target CXCR4 or CXCL12 have been developed to interfere with tumor growth, including pharmacological inhibitors, antagonists, and specific antibodies. This chemokine ligand/receptor pair was also proposed to represent an innovative therapeutic target for the treatment of ovarian cancer. Thus, a thorough understanding of ovarian cancer biology, and how chemokines may control these different biological activities might lead to the development of more effective therapies. This paper will focus on the current biology of CXCL12/CXCR4 axis in the context of understanding their potential role in ovarian cancer development.

Prognostic significance of CXCL12 expression in patients with colorectal carcinoma

The present study investigated the protein expression level of CXCL12 in colorectal cancer and aimed to elucidate its association with prognosis. CXCL12 positivity in 50% or more of tumor cells was defined as high expression and that in less than 50% of the tumor cells as low expression. CXCL12+ tumor budding at the invasive front was divided into 2 grades: high with 10 or more budding foci per x200 field of view and low grade with fewer than 10 budding foci. Patients with high expression (72.7%) and high grade CXCL12+ tumor budding (43.0%) had significantly shorter survival than patients with low expression (P = .014) and low grade (P = .003), respectively. Patients with a combination of high expression and high grade had the worst outcome (P < .001). Our study demonstrated that CXCL12 expression in colorectal cancer cells and at sites of budding were significant prognostic factors. Furthermore, together with lymph node metastasis, a combination of both expression patterns was a more powerful independent prognostic factor.

Chemokine signaling in cancer: one hump or two?

Chemokines and their receptors play essential roles in the development and function of multiple tissues. Chemokine expression, particularly CXCL12 and its receptor CXCR4, has prognostic significance in several cancers apparently due to chemokine mediated growth and metastatic spread. These observations provide the rationale for pursuing CXCR4 inhibition for cancer chemotherapy. However, the multiple homeostatic functions of CXCR4 may preclude global inhibition as a therapeutic strategy. Here I review CXCR4 signaling and how it might differ in normal and transformed cells with special emphasis on the role that altered CXCR4 counter-regulation might play in tumor biology. I propose that CXCR4 mediates unique signals in cancer cells as a consequence of abnormal counter-regulation and that this results in novel biological responses. The importance of testing this hypothesis lies in the possibility that targeting abnormal CXCR4 signaling might provide an anti-tumor effect without disturbing normal CXCR4 functions.

Expression of CXCL12 and its receptor CXCR4 correlates with lymph node metastasis in submucosal esophageal cancer

BACKGROUND AND OBJECTIVES

The chemokine CXCL12 and its receptor CXCR4 are involved in cell migration, proliferation, and angiogenesis, and promote organ-specific localization of distant metastases in various carcinomas. We examined their expression and microvessel density (MVD) in submucosal esophageal squamous cell carcinoma (ESCC) and analyzed their connection to clinicopathological findings including lymph node micrometastasis (LMM).

METHODS

Eighty-six patients with submucosal ESCC underwent curative resection from 1985 to 2002. Immunohistochemical staining of CXCL12, CXCR4, and CD34 was performed with primary tumors, and staining of cytokeratin was performed with dissected lymph nodes. MVD was calculated from CD34 expression, and LMM detected by cytokeratin staining.

RESULTS

Expression of CXCL12, but not CXCR4, correlated with lymph node metastasis. There was no significant correlation between the expression of CXCL12 and/or CXCR4 and MVD. LMM was detected in 8 cases and 14 lymph nodes. CXCL12 expression and high MVD were found in tumors with lymph node metastasis including LMM. Furthermore, in the CXCR4-positive tumors, positive CXCL12 expression was more significantly correlated with lymph node metastasis and/or LMM than negative CXCL12 expression.

CONCLUSIONS

Evaluation of CXCL12 and CXCR4 expression should assist detection of lymph node metastasis including LMM in submucosal ESCC.

Multiple roles of chemokine CXCL12 in the central nervous system: a migration from immunology to neurobiology

Chemotactic cytokines (chemokines) have been traditionally defined as small (10-14kDa) secreted leukocyte chemoattractants. However, chemokines and their cognate receptors are constitutively expressed in the central nervous system (CNS) where immune activities are under stringent control. Why and how the CNS uses the chemokine system to carry out its complex physiological functions has intrigued neurobiologists. Here, we focus on chemokine CXCL12 and its receptor CXCR4 that have been widely characterized in peripheral tissues and delineate their main functions in the CNS. Extensive evidence supports CXCL12 as a key regulator for early development of the CNS. CXCR4 signaling is required for the migration of neuronal precursors, axon guidance/pathfinding and maintenance of neural progenitor cells (NPCs). In the mature CNS, CXCL12 modulates neurotransmission, neurotoxicity and neuroglial interactions. Thus, chemokines represent an inherent system that helps establish and maintain CNS homeostasis. In addition, growing evidence implicates altered expression of CXCL12 and CXCR4 in the pathogenesis of CNS disorders such as HIV-associated encephalopathy, brain tumor, stroke and multiple sclerosis (MS), making them the plausible targets for future pharmacological intervention.

In vivo tracking of superparamagnetic iron oxide nanoparticle–labeled mesenchymal stem cell tropism to malignant gliomas using magnetic resonance imaging

Object

Mesenchymal stem cells (MSCs) have been shown to migrate toward tumors, but their distribution pattern in gliomas has not been completely portrayed. The primary purpose of the study was to assay the tropism capacity of MSCs to gliomas, to delineate the pattern of MSC distribution in gliomas after systemic injection, and to track the migration and incorporation of magnetically labeled MSCs using 1.5-T magnetic resonance (MR) imaging.

Methods

The MSCs from Fischer 344 rats were colabeled with superparamagnetic iron oxide nanoparticles (SPIO) and enhanced green fluorescent protein (EGFP). The tropism capacity of MSCs was quantitatively assayed in vitro using the Transwell system. To track the migration of MSCs in vivo, MR imaging was performed both 7 and 14 days after systemic administration of labeled MSCs. After MR imaging, the distribution patterns of MSCs in rats with gliomas were examined using Prussian blue and fluorescence staining.

Results

The in vitro study showed that MSCs possessed significantly greater migratory capacity than fibroblast cells (p < 0.001) and that lysis of F98 glioma cells and cultured F98 cells showed a greater capacity to induce migration of cells than other stimuli (p < 0.05). Seven days after MSC transplantation, the SPIO–EGFP colabeled cells were distributed throughout the tumor, where a well-defined dark hypointense region was represented on gradient echo sequences. After 14 days, most of the colabeled MSCs were found at the border between the tumor and normal parenchyma, which was represented on gradient echo sequences as diluted amorphous dark areas at the edge of the tumors.

Conclusions

This study demonstrated that systemically transplanted MSCs migrate toward gliomas with high specificity in a temporal–spatial pattern, which can be tracked using MR imaging.

Stem cell-like glioma cells promote tumor angiogenesis through vascular endothelial growth factor

Malignant gliomas are highly lethal cancers dependent on angiogenesis. Critical tumor subpopulations within gliomas share characteristics with neural stem cells. We examined the potential of stem cell-like glioma cells (SCLGC) to support tumor angiogenesis. SCLGC isolated from human glioblastoma biopsy specimens and xenografts potently generated tumors when implanted into the brains of immunocompromised mice, whereas non-SCLGC tumor cells isolated from only a few tumors formed secondary tumors when xenotransplanted. Tumors derived from SCLGC were morphologically distinguishable from non-SCLGC tumor populations by widespread tumor angiogenesis, necrosis, and hemorrhage. To determine a potential molecular mechanism for SCLGC in angiogenesis, we measured the expression of a panel of angiogenic factors secreted by SCLGC. In comparison with matched non-SCLGC populations, SCLGC consistently secreted markedly elevated levels of vascular endothelial growth factor (VEGF), which were further induced by hypoxia. In an in vitro model of angiogenesis, SCLGC-conditioned medium significantly increased endothelial cell migration and tube formation compared with non-SCLGC tumor cell-conditioned medium. The proangiogenic effects of glioma SCLGC on endothelial cells were specifically abolished by the anti-VEGF neutralizing antibody bevacizumab, which is in clinical use for cancer therapy. Furthermore, bevacizumab displayed potent antiangiogenic efficacy in vivo and suppressed growth of xenografts derived from SCLGC but limited efficacy against xenografts derived from a matched non-SCLGC population. Together these data indicate that stem cell-like tumor cells can be a crucial source of key angiogenic factors in cancers and that targeting proangiogenic factors from stem cell-like tumor populations may be critical for patient therapy.

Chemokines and chemokine receptors in neurological disease: raise, retain, or reduce?

Chemokines and chemokine receptors comprise a large number of molecules implicated in a wide range of physiological and pathological functions. Numerous studies have demonstrated the roles of chemokines and chemokine receptors: 1) during development, by regulating hematopoiesis, cardiogenesis, and vascular and cerebellar development; 2) during tumor biology, by controlling cell proliferation, angiogenesis, and metastasis; and 3), especially during leukocyte migration, by acting on firm adhesion, locomotion, diapedesis, and chemotaxis. This review focuses on chemokine and chemokine receptor involvement in diverse neurological diseases and their therapeutic potentials. Because of its induction or upregulation during CNS pathologies, members of the chemokine system can be used as biological markers. CXCR4 and CXCL12, by the correlation between their expression and the glioblastoma tumor progression, could be a marker to grade this type of CNS tumor. CCR1, by virtue of specific expression in Abeta plaques, may be a marker for Alzheimer pathology. Downregulation of CCL2 in cerebrospinal fluid may be a candidate to characterize multiple sclerosis (MS), but needs additional investigation. Moreover, chemokines and chemokine receptors represent interesting therapeutic targets. Using chemokine receptor antagonists, several studies provided exciting findings for potential neurological disease treatment. Chemokine receptor antagonists reduce disease severity in animal models of MS. In glioblastoma, a CXCR4 antagonist (AMD3100) showed an inhibition of tumor growth. Inhibition of chemokine receptor signaling is not the only therapeutic strategy: for example, CXCR4-CXCL12 has anti-inflammatory properties and CX3CL1-CX3CR1 controls neurotoxicity. Thus, chemokine biology suggests several approaches for treating neurological disease.

Clinical implication of CXCL12 expression in gastric cancer

PURPOSE

Recent research has revealed that tumor cells expressing chemokine receptors have a crucial impact on patient survival. However, there is no information regarding chemokine expression in gastro-intestinal cancer. This study immunohistochemically investigated CXCL12 expression in gastric cancer and evaluated its association with clinical factors, including patient prognosis.

METHOD

A total of 185 gastric cancer patients receiving curative gastrectomy were assessed. CXCL12 expression was evaluated by immunohistochemical analysis. Tumors with CXCL12-positive cancer cells were regarded as CXCL12 positive, and according to the degree of CXCL12 expression, patients were divided into three groups (weak, 31 cases; moderate, 27 cases; strong, 20 cases). Correlations between CXCL12 expression and clinical factors in gastric cancer were then determined.

RESULTS

CXCL12 was found in the cellular membrane of cancer cells. Seventy-four of 185 patients were classified into the CXCL12-positive group. Patients were divided into three groups according to the positivity of CXCL12 expression. Significant associations between CXCL12 and lymph node metastases (p < 0.05), depth of invasion (p < 0.01), lymphatic invasion (p < 0.01), tumor diameter (p < 0.05), and clinical stage (p < 0.01) were seen. Univariate analysis revealed that the CXCL12-positive group had significantly poorer surgical outcome than the CXCL12-negative group (p < 0.01). Multivariate analysis revealed CXCL12 to be an independent prognostic factor in gastric cancer (p = 0.02).

CONCLUSION

Cancerous CXCL12 positivity was determined to be an independent prognostic factor in gastric cancer, with CXCL12-positive gastric cancer showing more-aggressive behavior. Autocrine CXCL12 secretion from tumor cells may activate CXCR-4 on the tumor cells, which may be related to of the viability of distant metastases.

In ovarian cancer the prognostic influence of HER2/neu is not dependent on the CXCR4/SDF-1 signalling pathway

HER2/neu overexpression is a driving force in the carcinogenesis of several human cancers. In breast cancer the prognostic influence of HER2/neu was shown to be at least partly based on increased metastatic potential mediated by the chemokine–chemokine receptor pair SDF-1(CXCL12)/CXCR4. We wanted to evaluate the influence of HER2/neu on ovarian cancer prognosis and to investigate whether compromised survival would correlate with CXCR4 expression and/or SDF-1 abundance. Therefore, we analysed HER2/neu, CXCR4, and SDF-1 in 148 ovarian tumour samples by means of immunohistochemistry on tissue microarrays. Overexpression of HER2/neu was found in 27.6% of ovarian cancer tissues and in 15% of ovarian borderline tumours. In ovarian cancer patients, overexpression of HER2/neu correlated closely with overall survival (univariate hazard ratio (HR) 2.59, P=0.005; multiple corrected HR 1.92, P=0.074). In contrast, CXCR4 expression and SDF-1 abundance had no impact on overall survival, and both parameters were not correlated with HER2/neu expression. As expected, cytoplasmic CXCR4 expression and SDF-1 abundance correlated closely (P<0.0001). Our results confirm a univariate influence of HER2/neu expression on overall survival, which was completely independent of the expression of CXCR4 and the abundance of SDF-1, implying significant differences between the HER2/neu downstream pathways in ovarian cancer compared with breast cancer.

Expression of CXC chemokine receptors 1-5 and their ligands in human glioma tissues: role of CXCR4 and SDF1 in glioma cell proliferation and migration

Chemokines have been involved in cellular processes associated to malignant transformation such as proliferation, migration and angiogenesis. The expression of five CXC chemokine receptors and their main ligands was analysed by RT-PCR in 31 human astrocytic neoplasms. The mRNAs for all the receptors analysed were identified in a high percentage of tumours, while their ligands showed lower expression. CXCR4 and SDF1 were the most frequently mRNA identified (29/31 and 13/31 of the gliomas studied, respectively). Thus, we further analysed the cell localization of CXCR4 and SDF1 in immunohistochemistry experiments. We show a marked co-localization of CXCR4 and SDF1 in tumour cells, mainly evident in psudolpalisade and microcystic degeneration areas and in the vascular endothelium. In addition, hSDF1alpha induced a significant increase of DNA synthesis in primary human glioblastoma cell cultures and chemotaxis in a glioblastoma cell line. These results provide evidence of the expression of multiple CXC chemokines and their receptors in brain tumours and that in particular CXCR4 and SDF1 sustain proliferation and migration of glioma cells to promote malignant progression.