Imaging CXCL12-CXCR4 Signaling in Ovarian Cancer Therapy

Chemokine CXCL12 and receptor CXCR4 have emerged as promising therapeutic targets for ovarian cancer, a disease that continues to have a dismal prognosis. CXCL12-CXCR4 signaling drives proliferation, survival, and invasion of ovarian cancer cells, leading to tumor growth and metastasis. Pleiotropic effects of CXCR4 in multiple key steps in ovarian cancer suggest that blocking this pathway will improve outcomes for patients with this disease. To quantify CXCL12-CXCR4 signaling in cell-based assays and living mouse models of ovarian cancer, we developed a click beetle red luciferase complementation reporter that detects activation of CXCR4 based on recruitment of the cytosolic adapter protein β-arrestin 2. Both in two-dimensional and three-dimensional cell cultures, we established that bioluminescence from this reporter measures CXCL12-dependent activation of CXCR4 and inhibition of this pathway with AMD3100, a clinically-approved small molecule that blocks CXCL12-CXCR4 binding. We used this imaging system to quantify CXCL12-CXCR4 signaling in a mouse model of metastatic ovarian cancer and showed that treatment with AMD3100 interrupted this pathway in vivo. Combination therapy with AMD3100 and cisplatin significantly decreased tumor burden in mice, although differences in overall survival were not significantly greater than treatment with either agent as monotherapy. These studies establish a molecular imaging reporter system for analyzing CXCL12-CXCR4 signaling in ovarian cancer, which can be used to investigate biology and therapeutic targeting of this pathway in cell-based assays and living mice.     

Insights into the mechanism of enhanced mobilization of hematopoietic progenitor cells and release of CXCL12 by a combination of AMD3100 and aminoglycoside-polyarginine conjugates

Mobilization of hematopoietic stem and progenitor cells (HSPCs) from the bone marrow to the peripheral blood is utilized in clinical HSPC transplantation protocols. Retention of HSPCs in the bone marrow is determined by relationships between the chemokine chemokine (C-X-C motif) ligand 12 (CXCL12) and its major receptor C-X-C chemokine receptor type 4 (CXCR4), and disruption of this retention by CXCR4 antagonists such as AMD3100 induces rapid HSPC mobilization. Here, we report that aminoglycoside-polyarginine conjugates (APACs) and N-α-acetyl-nona-D-arginine (r9) induce mobilization of white blood cells and, preferentially, immature hematopoietic progenitor cells (HPCs) in mice, similarly to AMD3100. Remarkably, administration of AMD3100 with each one of the APACs or r9 caused additional HPC mobilization. The mobilizing activity of APACs and r9 was accompanied by a significant elevation in plasma CXCL12 levels. To further understand how APACs, r9 and their combinations with AMD3100 compete with CXCL12 binding to CXCR4, as well with antibody against CXCR4 for CXCR4 binding, we have undertaken an approach combining experimental validation and docking to determine plausible binding modes for these ligands. On the basis of our biological and docking findings, and recently published NMR data, we suggest that combination of pairs of compounds such as APACs (or r9) with AMD3100 induces more efficient disruption of the CXCL12-CXCR4 interaction than AMD3100 alone, resulting in enhanced HPC mobilization.     

CXCL14 is no direct modulator of CXCR4

C-X-C motif chemokine 12/C-X-C chemokine receptor type 4 (CXCL12/CXCR4) signaling is involved in ontogenesis, hematopoiesis, immune function and cancer. Recently, the orphan chemokine CXCL14 was reported to inhibit CXCL12-induced chemotaxis – probably by allosteric modulation of CXCR4. We thus examined the effects of CXCL14 on CXCR4 regulation and function using CXCR4-transfected human embryonic kidney (HEK293) cells and Jurkat T cells. CXCL14 did not affect dose–response profiles of CXCL12-induced CXCR4 phosphorylation, G protein-mediated calcium mobilization, dynamic mass redistribution, kinetics of extracellular signal-regulated kinase 1 (ERK1) and ERK2 phosphorylation or CXCR4 internalization. Hence, essential CXCL12-operated functions of CXCR4 are insensitive to CXCL14, suggesting that interactions of CXCL12 and CXCL14 pathways depend on a yet to be identified CXCL14 receptor.     

Secreted CXCL12 (SDF-1) forms dimers under physiological conditions

Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.     

CXCL13-CXCR5 axis: Regulation in inflammatory diseases and cancer

Chemokine C-X-C motif ligand 13 (CXCL13), originally identified as a B-cell chemokine, plays an important role in the immune system. The interaction between CXCL13 and its receptor, the G-protein coupled receptor (GPCR) CXCR5, builds a signaling network that regulates not only normal organisms but also the development of many diseases. However, the precise action mechanism remains unclear. In this review, we discussed the functional mechanisms of the CXCL13-CXCR5 axis under normal conditions, with special focus on its association with diseases. For certain refractory diseases, we emphasize the diagnostic and therapeutic role of CXCL13-CXCR5 axis.     

趋化因子SD-1及其受体CXCR4在卵巢癌中的研究进展

基质细胞衍生因子-1(Stromal cell derived factor-1,SDF-1)是CXC趋化因子家族的重要成员,系统命名为CXCL12,能与它的唯一受体CXC趋化因子受体-4(CXC chemokine receptor-4,CXCR4)形成CXCL12-CXCR4生物学轴,CXCL12-CXCR4生物学轴在肿瘤生长、侵袭、转移过程中发生重要作用。到目前为止,已发现CXCL12-CXCR4在卵巢癌、胰腺癌、肝癌等多种肿瘤组织中表达。然而,国内目前还没有关于CXCL12-CXCR4与卵巢癌关系的相关综述,本文将从趋化因子CXCL12及其受体CXCR4,CXCL12/CXCR4轴与卵巢癌细胞系实验研究,CXCL12-CXCR4轴与卵巢癌的临床研究,CXCL12/CXCR4与卵巢癌预后,CXCL12/CXCR4与卵巢癌治疗展望等五个方面对CXCL12-CXCR4生物轴与卵巢癌的关系,及其在卵巢癌治疗中的应用展开综述。     

The CXCL8-CXCR1/2 pathways in cancer

Persistent infection or chronic inflammation contributes significantly to tumourigenesis and tumour progression. C-X-C motif ligand 8 (CXCL8) is a chemokine that acts as an important multifunctional cytokine to modulate tumour proliferation, invasion and migration in an autocrine or paracrine manner. Studies have suggested that CXCL8 and its cognate receptors, C-X-C chemokine receptor 1 (CXCR1) and C-X-C chemokine receptor 2 (CXCR2), mediate the initiation and development of various cancers including breast cancer, prostate cancer, lung cancer, colorectal carcinoma and melanoma. CXCL8 also integrates with multiple intracellular signalling pathways to produce coordinated effects. Neovascularisation, which provides a basis for fostering tumour growth and metastasis, is now recognised as a critical function of CXCL8 in the tumour microenvironment. In this review, we summarize the biological functions and clinical significance of the CXCL8 signalling axis in cancer. We also propose that CXCL8 may be a potential therapeutic target for cancer treatment.     

Carboxy-terminus of CXCR7 regulates receptor localization and function

Chemokine receptor CXCR7 is essential for normal development, and this receptor promotes initiation and progression of diseases including cancer and autoimmunity. To understand normal and pathologic functions of CXCR7 and advance development of therapeutic agents, there is a need to define structural domains that regulate this receptor. We generated mutants of CXCR7 with deletion of different lengths of the predicted intracellular tail and analyzed effects on CXCR7 signaling and function in cell-based assays. While wild-type CXCR7 predominantly localized to intracellular vesicles, progressive deletion of the carboxy terminus redistributed the receptor to the plasma membrane. Truncating the intracellular tail of CXCR7 did not alter binding to CXCL12, but mutant receptors had reduced scavenging of this chemokine. Using a firefly luciferase complementation system, we established that deletions of the carboxy terminus decreased basal interactions and eliminated ligand-dependent recruitment of the scaffolding protein β-arrestin-2 to receptors. Deleting the carboxy terminus of CXCR7 impaired constitutive internalization of the receptor and reduced activation of ERK1/2 by CXCL12-CXCR7. Inhibiting dynamin, a molecule required for internalization of CXCR7, increased ligand-dependent association of the receptor with β-arrestin-2 and enhanced activation of ERK1/2. These studies establish mechanisms of action for CXCR7 and establish the intracellular tail of CXCR7 as a critical determinant of receptor trafficking, chemokine scavenging, and signaling.     

Fluorescent CXCL12AF647 as a novel probe for nonradioactive CXCL12/CXCR4 cellular interaction studies.

BACKGROUND: Chemokines drive the migration of leukocytes via interaction with specific G protein-coupled 7-transmembrane receptors. The chemokine ligand/receptor pair stromal cell-derived factor-1 (SDF-1, CXCL12)/CXCR4 is gaining increasing interest because of its involvement in the metastasis of several types of cancer and in certain inflammatory autoimmune disorders such as rheumatoid arthritis. In addition, CXCR4 serves as an important coreceptor for cellular entry of T-tropic strains of human immunodeficiency virus (HIV). Therefore, potent and specific CXCR4 antagonists may have therapeutic potential as anti-HIV, anti-cancer, and anti-inflammatory drugs. METHODS AND RESULTS: Chemokine receptor antagonists can be identified by their ability to inhibit ligand binding to the receptor protein. Until now, chemokine binding assays were mostly performed with radiolabeled chemokine ligands such as [(125)I]CXCL12. To overcome the practical problems associated with such radioactive chemokine binding assays, we have developed a flow cytometric technique using a new, commercially available Alexa Fluor 647 conjugate of CXCL12 (CXCL12(AF647)). Calcium flux, chemotaxis, and p44/42 mitogen-activated protein kinase phosphorylation assays showed that the agonistic activity of the fluorescent CXCL12 was unchanged as compared with that of unlabeled CXCL12. Human T-lymphoid (CXCR4(+)) SupT1 cells and CXCR4-transfected, but not CCR5- or CXCR3-transfected, human astroglioma U87.CD4 cells specifically bound CXCL12(AF647) in a concentration-dependent manner. Unlabeled CXCL12 and the well-known CXCR4 inhibitors, AMD3100 and T22, blocked the binding of CXCL12(AF647) to SupT1 cells with 50% inhibitory concentrations of 92, 13, and 8 ng/ml, respectively. We have also used this method to evaluate CXCL12 binding and CXCR4 expression level in different subsets of human peripheral blood mononuclear cells. CONCLUSION: CXCL12(AF647) is a valuable, more convenient alternative for [(125)I]CXCL12 in ligand/receptor interaction studies.     

CXCR7 mediated Giα independent activation of ERK and Akt promotes cell survival and chemotaxis in T cells

Chemokine receptors CXCR7 and CXCR4 bind to the same ligand stromal cell derived factor-1alpha (SDF-1α/CXCL12). We assessed the downstream signaling pathways mediated by CXCL12-CXCR7 interaction in Jurkat T cells. All experiments were carried out after functionally blocking the CXCR4 receptor. CXCL12, on binding CXCR7, induced phosphorylation of extra cellular regulated protein kinases (ERK 1/2) and Akt. Selective inhibition of each signal demonstrated that phosphorylated ERK 1/2 is essential for chemotaxis and survival of T cells whereas activation of Akt promotes only cell survival. Another interesting finding of this study is that CXCL12-CXCR7 interaction under normal physiological conditions does not activate the p38 pathway. Furthermore, we observed that the CXCL12 signaling via CXCR7 is Giα independent. Our findings suggest that CXCR7 promotes cell survival and does not induce cell death in T cells. The CXCL12 signaling via CXCR7 may be crucial in determining the fate of the activated T cells.     

The Chemokine Receptor CXCR4 and c-MET Cooperatively Promote Epithelial-Mesenchymal Transition in Gastric Cancer Cells

The C-X-C motif chemokine receptor 4 (CXCR4) pathway can promote tumor metastasis but is dependent on cross talk with other signaling pathways. The MET proto-oncogene (c-MET) participates in metastasis and is highly expressed in gastric cancer. However, the relationship between CXCR4 and c-MET signaling and their mechanisms of action in gastric cancer metastasis remain unclear. In this study, in vitro experiments demonstrated that C-X-C motif chemokine ligand 12 (CXCL12)/CXCR4 induces epithelial-mesenchymal transition (EMT) and promotes migration in gastric cancer cells, which is accompanied by c-MET activation. These phenomena were reversed by c-MET inhibition. Further investigation revealed that c-MET activation correlated with its interaction with caveolin 1 in lipid rafts, induced by CXCL12. In clinical samples, we observed a significant positive association between CXCR4 expression and c-MET phosphorylation (r = 0.259, P = .005). Moreover, samples expressing both receptors were found to indicate significantly poorer patient prognosis (P < .001). These results suggest that CXCL12 induces EMT at least partially through cross talk between CXCR4 and c-MET signaling. In addition, changes in these pathways could have clinical importance for the treatment of gastric cancer.     

Functional and structural consequences of chemokine (C-X-C motif) receptor 4 activation with cognate and non-cognate agonists

Chemokine (C-X-C motif) receptor 4 (CXCR4) regulates cell trafficking and plays important roles in the immune system. Ubiquitin has recently been identified as an endogenous non-cognate agonist of CXCR4, which activates CXCR4 via interaction sites that are distinct from those of the cognate agonist C-X-C motif chemokine ligand 12 (CXCL12). As compared with CXCL12, chemotactic activities of ubiquitin in primary human cells are poorly characterized. Furthermore, evidence for functional selectivity of CXCR4 agonists is lacking, and structural consequences of ubiquitin binding to CXCR4 are unknown. Here, we show that ubiquitin and CXCL12 have comparable chemotactic activities in normal human peripheral blood mononuclear cells, monocytes, vascular smooth muscle, and endothelial cells. Chemotactic activities of the CXCR4 ligands could be inhibited with the selective CXCR4 antagonist AMD3100 and with a peptide analogue of the second transmembrane domain of CXCR4. In human monocytes, ubiquitin- and CXCL12-induced chemotaxis could be inhibited with pertussis toxin and with inhibitors of phospholipase C, phosphatidylinositol 3 kinase, and extracellular signal-regulated kinase 1/2. Both agonists induced inositol trisphosphate production in vascular smooth muscle cells, which could be inhibited with AMD3100. In β-arrestin recruitment assays, ubiquitin did not sufficiently recruit β-arrestin2 to CXCR4 (EC₅₀ > 10 μM), whereas the EC₅₀ for CXCL12 was 4.6 nM (95% confidence interval 3.1–6.1 nM). Both agonists induced similar chemical shift changes in the ¹³C-¹H-heteronuclear single quantum correlation (HSQC) spectrum of CXCR4 in membranes, whereas CXCL11 did not significantly alter the ¹³C-¹H-HSQC spectrum of CXCR4. Our findings point towards ubiquitin as a biased agonist of CXCR4.     

Silibinin,a novel chemokine receptor type 4 antagonist,inhibits chemokine ligand 12-induced migration in breast cancer cells

PurposeC-X-C chemokine receptor type 4 (CXCR4) signaling has been demonstrated to be involved in cancer invasion and migration; therefore, CXCR4 antagonist can serve as an anti-cancer drug by preventing tumor metastasis. This study aimed to identify the CXCR4 antagonists that could reduce and/or inhibit tumor metastasis from natural products.Methods and resultsAccording to the molecular docking screening, we reported here silibinin as a novel CXCR4 antagonist. Biochemical characterization showed that silibinin blocked chemokine ligand 12 (CXCL12)-induced CXCR4 internalization by competitive binding to CXCR4, therefore inhibiting downstream intracellular signaling. In human breast cancer cells MDA-MB-231, which expresses high levels of CXCR4, inhibition of CXCL12-induced chemomigration can be found under silibinin treatment. Overexpression of CXCL12 sensitized MDA-MB-231 cells to the inhibition of silibinin, which was abolished by CXCR4 knockdown. The inhibition of silibinin was also observed in MCF-7/CXCR4 cells rather than MCF-7 cells that express low level of CXCR4.ConclusionsOur work demonstrated that silibinin is a novel CXCR4 antagonist that may have potential therapeutic use for prevention of tumor metastasis.     

Synthetic chemokines directly labeled with a fluorescent dye as tools for studying chemokine and chemokine receptor interactions

Chemokines constitute a protein family that exhibit a variety of biological activities involved in normal and pathological physiological processes. CCL11 (eotaxin), CCL19 (MIP-3beta), CCL22 (MDC), CXCL11 (I-TAC) and CXCL12 (SDF-1alpha) chemokines, modified with the Alexa Fluor 647 fluorescent dye at specific positions along their sequence, were produced by a chemical route and their biological activities were characterized. In a migration assay, fluorescent chemokines were as biologically active as the unmodified forms. All labeled chemokines specifically stained cell lines transfected with the appropriate human chemokine receptors. The specificity of binding was further established by showing that the unlabeled ligands efficiently competed with the labeled chemokines for binding to their respective receptor. A low molecular weight antagonist of CXCR4 prevented binding of labeled CXCL12 to CXCR4 comparably to a neutralizing anti-CXCR4 antibody. Finally, labeled CCL19 was used for the staining of primary cells, illustrating that this reagent can be used for studying CCR7 expression on different cell types. Together, these results demonstrate that fluorescent synthetic chemokines constitute promising ligands for the development of chemokine receptor-binding assays on intact cells, for applications such as cell-based, high throughput screening, and studies of chemokine receptor expression by primary cells.     

Consequences of ChemR23 Heteromerization with the Chemokine Receptors CXCR4 and CCR7

Recent studies have shown that heteromerization of the chemokine receptors CCR2, CCR5 and CXCR4 is associated to negative binding cooperativity. In the present study, we build on these previous results, and investigate the consequences of chemokine receptor heteromerization with ChemR23, the receptor of chemerin, a leukocyte chemoattractant protein structurally unrelated to chemokines. We show, using BRET and HTRF assays, that ChemR23 forms homomers, and provide data suggesting that ChemR23 also forms heteromers with the chemokine receptors CCR7 and CXCR4. As previously described for other chemokine receptor heteromers, negative binding cooperativity was detected between ChemR23 and chemokine receptors, i.e. the ligands of one receptor competed for the binding of a specific tracer of the other. We also showed, using mouse bone marrow-derived dendritic cells prepared from wild-type and ChemR23 knockout mice, that ChemR23-specific ligands cross-inhibited CXCL12 binding on CXCR4 in a ChemR23-dependent manner, supporting the relevance of the ChemR23/CXCR4 interaction in native leukocytes. Finally, and in contrast to the situation encountered for other previously characterized CXCR4 heteromers, we showed that the CXCR4-specific antagonist AMD3100 did not cross-inhibit chemerin binding in cells co-expressing ChemR23 and CXCR4, demonstrating that cross-regulation by AMD3100 depends on the nature of receptor partners with which CXCR4 is co-expressed.     

Small neutralizing molecules to inhibit actions of the chemokine CXCL12

The chemokine CXCL12 and the receptor CXCR4 play pivotal roles in normal vascular and neuronal development, in inflammatory responses, and in infectious diseases and cancer. For instance, CXCL12 has been shown to mediate human immunodeficiency virus-induced neurotoxicity, proliferative retinopathy and chronic inflammation, whereas its receptor CXCR4 is involved in human immunodeficiency virus infection, cancer metastasis and in the rare disease known as the warts, hypogammaglobulinemia, immunodeficiency, and myelokathexis (WHIM) syndrome. As we screened chemical libraries to find inhibitors of the interaction between CXCL12 and the receptor CXCR4, we identified synthetic compounds from the family of chalcones that reduce binding of CXCL12 to CXCR4, inhibit calcium responses mediated by the receptor, and prevent CXCR4 internalization in response to CXCL12. We found that the chemical compounds display an original mechanism of action as they bind to the chemokine but not to CXCR4. The highest affinity molecule blocked chemotaxis of human peripheral blood lymphocytes ex vivo. It was also active in vivo in a mouse model of allergic eosinophilic airway inflammation in which we detected inhibition of the inflammatory infiltrate. The compound showed selectivity for CXCL12 and not for CCL5 and CXCL8 chemokines and blocked CXCL12 binding to its second receptor, CXCR7. By analogy to the effect of neutralizing antibodies, this molecule behaves as a small organic neutralizing compound that may prove to have valuable pharmacological and therapeutic potential.     

Cortisol-induced CXCR4 augmentation mobilizes T lymphocytes after acute physical stress

The aim of this study was to elucidate the mechanism responsible for lymphopenia after exercise. Seven young healthy men volunteered for this study. Peripheral blood mononuclear cells (PBMC) were cultured with cortisol and analyzed for C-X-C motif chemokine receptor 4 (CXCR4) expression by flow cytometry. To determine the effects of exercise, subjects performed exhaustive cycling exercise. PBMC were cultured with plasma obtained before and after the cycling exercise. Alternatively, PBMC obtained before and after exercise were cultured without plasma or glucocorticoid to examine whether PBMC were primed in vivo for CXCR4 expression. We analyzed cortisol- or plasma-treated PBMC to determine their ability to migrate through membrane filters in response to stromal cell-derived factor 1alpha/CXCL12. Cortisol dose- and time-dependently augmented CXCR4 expression on T lymphocytes, with <6 h of treatment sufficient to augment CXCR4 on T lymphocytes. Postexercise plasma also augmented CXCR4 expression. Cortisol or postexercise plasma treatment markedly enhanced migration of T lymphocytes toward CXCL12. Augmentation of CXCR4 on T lymphocytes by cortisol or plasma was effectively blocked by the glucocorticoid receptor antagonist RU-486. Thus exercise-elicited endogenous cortisol effectively augments CXCR4 expression on T lymphocytes, which may account for lymphopenia after exercise.     

Grk2 is an Essential Regulator of CXCR7 Signalling in Astrocytes

We previously demonstrated that in astrocytes, SDF-1/CXCL12 exclusively signals through CXCR7 despite the additional presence of the alternate SDF-1/CXCL12 receptor, CXCR4. In addition, we provided evidence that astrocytic CXCR7-signalling involves a G protein-dependent mechanism. This is insofar remarkable as in all other cell types studied to date, CXCR7 either acts as a scavenger chemokine receptor, a modulator of CXCR4, or a non-classical chemokine receptor, signalling through ß-arrestin. To begin to unravel the molecular framework impinging the selective function of CXCR7 on a given cell type, we have now analysed the role of G protein-coupled receptor kinases (Grks) in astrocytic CXCR7 signalling. We demonstrate that Grk2 mediates signalling of SDF-1/CXCL12-bound CXCR7 as suggested by the finding that SDF-1/CXCL12-induced activation of Erk1/2 and Akt is abrogated following RNAi-mediated inhibition of Grk2, but not of Grk3, Grk5, or Grk6. We further unravel that Grk2 additionally controls signalling of SDF-1/CXCL12-bound CXCR7 in astrocytes by mediating internalization and subsequent silencing of CXCR7. Finally, we demonstrate that Grk2 is likewise expressed by microglial cells and Schwann cells, cell types in which CXCR7 does not act as a classical chemokine receptor. In conclusion, our findings establish that Grk2 tightly controls CXCR7 signalling in astrocytes, but does not imprint the cell type-specific function of this chemokine receptor.     

CXCR3, CXCL10 and type 1 diabetes

Type 1 diabetes (T1D) is due to antigen-specific assaults on the insulin producing pancreatic β-cells by diabetogenic T-helper (Th)1 cells. (C-X-C motif) ligand (CXCL)10, an interferon-γ inducible Th1 chemokine, and its receptor, (C-X-C motif) receptor (CXCR)3, have an important role in different autoimmune diseases. High circulating CXCL10 levels were detected in new onset T1D patients, in association with a Th1 autoimmune response. Furthermore β-cells produce CXCL10, under the influence of Th1 cytokines, that suppresses their proliferation. Viral β-cells infections induce cytokines and CXCL10 expression, inducing insulin-producing cell failure in T1D. CXCL10/CXCR3 system plays a critical role in the autoimmune process and in β-cells destruction in T1D. Blocking CXCL10 in new onset diabetes seems a possible approach for T1D treatment.     

Interstitial Fluid Flow Increases Hepatocellular Carcinoma Cell Invasion through CXCR4/CXCL12 and MEK/ERK Signaling

Hepatocellular carcinoma (HCC) is the most common form of liver cancer (~80%), and it is one of the few cancer types with rising incidence in the United States. This highly invasive cancer is very difficult to detect until its later stages, resulting in limited treatment options and low survival rates. There is a dearth of knowledge regarding the mechanisms associated with the effects of biomechanical forces such as interstitial fluid flow (IFF) on hepatocellular carcinoma invasion. We hypothesized that interstitial fluid flow enhanced hepatocellular carcinoma cell invasion through chemokine-mediated autologous chemotaxis. Utilizing a 3D in vitro invasion assay, we demonstrated that interstitial fluid flow promoted invasion of hepatocellular carcinoma derived cell lines. Furthermore, we showed that autologous chemotaxis influences this interstitial fluid flow-induced invasion of hepatocellular carcinoma derived cell lines via the C-X-C chemokine receptor type 4 (CXCR4)/C-X-C motif chemokine 12 (CXCL12) signaling axis. We also demonstrated that mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling affects interstitial fluid flow-induced invasion; however, this pathway was separate from CXCR4/CXCL12 signaling. This study demonstrates, for the first time, the potential role of interstitial fluid flow in hepatocellular carcinoma invasion. Uncovering the mechanisms that control hepatocellular carcinoma invasion will aid in enhancing current liver cancer therapies and provide better treatment options for patients.