CX3CL1 promotes tumour cell by inducing tyrosine phosphorylation of cortactin in lung cancer

It has been reported that chemokine CX₃CL1 can regulate various tumours by binding to its unique receptor CX₃CR1. However, the effect of CX₃CL1-CX₃CR1 on the lung adenocarcinoma and lung squamous cell carcinoma is still unclear. Here, we showed that CX₃CL1 can further invasion and migration of lung adenocarcinoma A549 and lung squamous cell carcinoma H520. In addition, Western blot and immunofluorescence test indicated CX₃CL1 up-regulated the phosphorylation level of cortactin, which is a marker of cell pseudopodium. Meanwhile, the phosphorylation levels of c-Src and c-Abl, which are closely related to the regulation of cortactin phosphorylation, are elevated. Nevertheless, the src/abl inhibitor bosutinib and mutations of cortactin phosphorylation site could inhibit the promotion effect of CX₃CL1 on invasion and migration of A549 and H520. Moreover, these results of MTT, Hoechst staining and Western blot suggested that CX₃CL1 had no effect on the proliferation and apoptosis of A549 and H520 in vitro. The effects of CX₃CL1 were also verified by the subcutaneous tumour formation in nude mice, which showed that it could promote proliferation and invasion of A549 in vivo. In summary, our results indicated that CX₃CL1 furthered invasion and migration in lung cancer cells partly via activating cortactin, and CX₃CL1 may be a potential molecule in regulating the migration and invasion of lung cancer.     

Identification of the chemokine CX3CL1 as a new regulator of malignant cell proliferation in epithelial ovarian cancer

Background

Little is known about the molecules that contribute to the growth of epithelial ovarian carcinomas (EOC), which remain the most lethal gynecological cancer in women. The chemokine Fractalkine/CX₃CL1 has been widely reported to play a biologically relevant role in tumor growth and spread. We report here the first investigation of the expression and role of CX₃CL1 in EOC.

Results

Epithelial cells from the surface of the ovary and the Fallopian tubes and from benign, borderline and malignant tumors all stained positive for CX₃CL1. In tumor specimens from 54 women who underwent surgical treatment for EOC diagnosis, CX₃CL1 immunoreactivity was unevenly distributed in epithelial tumor cells, and ranged from strong (33%) to absent (17%). This uneven distribution of CX₃CL1 did not reflect the morphological heterogeneity of EOC. It was positively correlated with the proliferation index Ki-67 and with GILZ (glucocorticoid-induced leucine zipper), previously identified as an activator of the proliferation of malignant EOC cells. Hierarchical clustering analysis, including age at diagnosis, tumor grade, FIGO stage, Ki-67 index, CX₃CL1, SDF-1/CXCL12 and GILZ immunostaining scores, distinguished two major clusters corresponding to low and high levels of proliferation and differing in terms of GILZ and CX₃CL1 expression. GILZ overexpression in the carcinoma-derived BG1 cell line resulted in parallel changes in CX₃CL1 products. Conversely, CX₃CL1 promoted through its binding to CX₃CR1 AKT activation and proliferation in BG1 cells. In a mouse subcutaneous xenograft model, the overexpression of GILZ was associated with higher expression of CX₃CL1 and faster tumor growth.

Conclusion

Our findings highlight the previously unappreciated constitutive expression of CX₃CL1 preceding tumorigenesis in ovarian epithelial cells. Together with GILZ, this chemokine emerges as a regulator of cell proliferation, which may be of potential clinical relevance for the selection of the most appropriate treatment for EOC patients.     

CX3CR1 Is Expressed by Human B Lymphocytes and Meditates CX3CL1 Driven Chemotaxis of Tonsil Centrocytes

Background

Fractalkine/CX₃CL1, a surface chemokine, binds to CX₃CR1 expressed by different lymphocyte subsets. Since CX₃CL1 has been detected in the germinal centres of secondary lymphoid tissue, in this study we have investigated CX₃CR1 expression and function in human naïve, germinal centre and memory B cells isolated from tonsil or peripheral blood.

Methodology/Principal Findings

We demonstrate unambiguously that highly purified human B cells from tonsil and peripheral blood expressed CX₃CR1 at mRNA and protein levels as assessed by quantitative PCR, flow cytometry and competition binding assays. In particular, naïve, germinal centre and memory B cells expressed CX₃CR1 but only germinal centre B cells were attracted by soluble CX₃CL1 in a transwell assay. CX₃CL1 signalling in germinal centre B cells involved PI3K, Erk1/2, p38, and Src phosphorylation, as assessed by Western blot experiments. CX₃CR1⁺ germinal centre B cells were devoid of centroblasts and enriched for centrocytes that migrated to soluble CX₃CL1. ELISA assay showed that soluble CX₃CL1 was secreted constitutively by follicular dendritic cells and T follicular helper cells, two cell populations homing in the germinal centre light zone as centrocytes. At variance with that observed in humans, soluble CX₃CL1 did not attract spleen B cells from wild type mice. OVA immunized CX₃CR1⁻/⁻ or CX₃CL1⁻/⁻ mice showed significantly decreased specific IgG production compared to wild type mice.

Conclusion/Significance

We propose a model whereby human follicular dendritic cells and T follicular helper cells release in the light zone of germinal centre soluble CX₃CL1 that attracts centrocytes. The functional implications of these results warrant further investigation.     

Hypoxia-Inducible Factor-1α Regulates Chemotactic Migration of Pancreatic Ductal Adenocarcinoma Cells through Directly Transactivating the CX3CR1 Gene

CX3CR1 is an important chemokine receptor and regulates the chemotactic migration of pancreatic ductal adenocarcinoma (PDAC) cells. Up to now, its regulatory mechanism remains largely undefined. Here, we report that hypoxia upregulates the expression of CX3CR1 in pancreatic cancer cells. When hypoxia-inducible factor (HIF)-1α expression was knocked down in vitro and in vivo, the expression of CX3CR1 was significantly decreased. Chromatin immunoprecipitation assay demonstrated that HIF-1α bound to the hypoxia-response element (HRE; 5'-A/GCGTG-3') of CX3CR1 promoter under normoxia, and this binding was significantly enhanced under hypoxia. Overexpression of HIF-1α significantly upregulated the expression of luciferase reporter gene under the control of the CX3CR1 promoter in pancreatic cancer cells. Importantly, we demonstrated that HIF-1α may regulate cancer cell migration through CX3CR1. The HIF-1α/CX3CR1 pathway might represent a valuable therapeutic target to prevent invasion and distant metastasis in PDAC.     

Constitutive Endocytosis of the Chemokine CX3CL1 Prevents Its Degradation by Cell Surface Metalloproteases

CX₃CL1, a chemokine with transmembrane and soluble species, plays a key role in inflammation by acting as both chemoattractant and adhesion molecule. CX₃CL1 is the only chemokine known to undergo constitutive internalization, raising the possibility that dynamic equilibrium between the endocytic compartment and the plasma membrane critically regulates the availability and processing of CX₃CL1 at the cell surface. We therefore investigated how transmembrane CX₃CL1 is internalized. Inhibition of dynamin using a nonfunctional allele or of clathrin using specific small interfering RNA prevented endocytosis of the chemokine in CX₃CL1-expressing human ECV-304 cells. Perusal of the cytoplasmic domain of CX₃CL1 revealed two putative adaptor protein-2 (AP-2)-binding motifs. Accordingly, CX₃CL1 co-localized with AP-2 at the plasma membrane. We generated a mutant allele of CX₃CL1 lacking the cytoplasmic tail. Deletion of the cytosolic tail precluded internalization of the chemokine. We used site-directed mutagenesis to disrupt AP-2-binding motifs, singly or in combination, which resulted in diminished internalization of CX₃CL1. Although CX₃CL1 was present in both superficial and endomembrane compartments, ADAM10 (a disintegrin and metalloprotease 10) and tumor necrosis factor-converting enzyme, the two metalloproteases that cleave CX₃CL1, localized predominantly to the plasmalemma. Inhibition of endocytosis using the dynamin inhibitor, Dynasore, promoted rapid metalloprotease-dependent shedding of CX₃CL1 from the cell surface into the surrounding medium. These findings indicate that the cytoplasmic tail of CX₃CL1 facilitates its constitutive clathrin-mediated endocytosis. Such regulation enables intracellular storage of a sizable pool of presynthesized CX₃CL1 that protects the chemokine from degradation by metalloproteases at the plasma membrane.Inflammation is marked by the migration of circulating leukocytes into sites of injury, a process that occurs via a series of coordinated interactions between leukocytes and endothelial or epithelial cells. Central to this process are chemokines, a family of low molecular weight proteins that can attract leukocytes bearing the complementary receptors. When engagement of the chemokine receptor occurs, the leukocyte becomes activated and is induced to firmly adhere to the inflamed endothelium. These initial steps culminate in diapedesis of the leukocyte across the endothelium and migration into the injured tissue. The local complement of chemokines elaborated is organ-specific and varies with the type of inflammation present. In addition, specific leukocyte subsets also bear distinct chemokine receptors. In this way, chemokines and chemokine receptors confer organ specificity to leukocyte migration and help to “fine-tune” the nature of the observed inflammatory response.Among the 40 chemokines identified so far, CX₃CL1 is one of only two that have a transmembrane structure (1, 2). The chemokine domain of CX₃CL1 binds to its complementary receptor, CX₃CR1, through two distinct amino acid residues (3). The mucin stalk of CX₃CL1 allows efficient presentation of the chemokine to circulating leukocytes that express CX₃CR1, thereby allowing these leukocytes to be captured by the underlying endothelium (4, 5). CX₃CL1 also possesses a cytoplasmic tail 37 amino acids in length. However, the specific functions of the cytoplasmic tail have been left completely unexplored.Accumulating evidence demonstrates a critical role for CX₃CL1 in the pathogenesis of diverse inflammatory diseases, including atherosclerosis, systemic lupus erythematosus, and rejection of transplanted organs (6–15). Cell surface expression of CX₃CL1 is known to be regulated by proteolytic cleavage, or shedding, from the plasma membrane (16–18). Constitutive cleavage of CX₃CL1 occurs at low levels and is mediated by ADAM10 (a disintegrin and metalloprotease 10) (17). In response to inflammatory stimulation with lipopolysaccharide or to protein kinase C activation using phorbol 12-myristate 13-acetate, proteolytic cleavage of CX₃CL1 is markedly enhanced. Inducible cleavage of CX₃CL1 is mediated by tumor necrosis factor-α converting enzyme (TACE; ADAM17),² a related protease of the metzincin family (16, 18).In addition to proteolytic cleavage, surface expression of CX₃CL1 is also regulated by subcellular trafficking. We recently demonstrated that cell surface CX₃CL1 rapidly recycles to and from a specialized endocytic compartment, raising the possibility that the intracellular pool serves as a storage depot and that dynamic equilibrium between the endocytic compartment and the plasma membrane determines the availability and processing of transmembrane CX₃CL1 (19). In the current study, we explored whether the unique cytoplasmic tail of CX₃CL1 is important for this novel mode of regulation of the chemokine and whether it affects susceptibility of the chemokine to surface proteases. Our data suggest that plasmalemmal CX₃CL1 undergoes constitutive clathrin-mediated endocytosis (CME), facilitating storage of an intracellular pool of chemokine that is protected from cell surface metalloproteases.     

Dissecting the autocrine and paracrine roles of the CCR2-CCL2 axis in tumor survival and angiogenesis

The CCL2 CCR2 axis is likely to contributes to the development and progression of cancer diseases by two major mechanisms; autocrine effect of CCL2 as a survival/growth factor for CCR2+ cancer cells and, the attraction of CCR2+ CX₃CR1+tumor associated macrophages that in the absence of CCR2 hardly migrate. Thus far no in vivo system has been set up to differentiate the selective contribution of each of these features to cancer development. Here we employed a chimera animal model in which all non-malignant cells are CCR2−/−, but all cancer cells are CCR2+, combined with an adoptive transfer system of bone marrow (BM) CX₃CR1+ cells from CCR2+ mice harboring a targeted replacement of the CX₃CR1gene by an enhanced green fluorescent protein (EGFP) reporter gene (cx₃cr1 ^gfp), together with the CD45.1 congene. Using this system we dissected the selective contribution of CX₃CR1+CCR2+ cells, which comprise only about 7% of CD11b+ BM cells, to tumor development and angiogenesis. Showing that aside for their direct pro-angiogenic effect they are essential for the recruitment of other CD11b+ cells to the tumor site. We further show that the administration of CCR2-Ig, that selectively and specifically neutralize CCL2, to mice in which CCR2 is expressed only on tumor cells, further suppressed tumor development, implicating for the key role of this chemokine supporting tumor survival in an autocrine manner. This further emphasizes the important role of CCL2 as a target for therapy of cancer diseases.     

Cytoskeletal confinement of CX3CL1 limits its susceptibility to proteolytic cleavage by ADAM10

CX₃CL1 is a unique chemokine that acts both as a transmembrane endothelial adhesion molecule and, upon proteolytic cleavage, a soluble chemoattractant for circulating leukocytes. The constitutive release of soluble CX₃CL1 requires the interaction of its transmembrane species with the integral membrane metalloprotease ADAM10, yet the mechanisms governing this process remain elusive. Using single-particle tracking and subdiffraction imaging, we studied how ADAM10 interacts with CX₃CL1. We observed that the majority of cell surface CX₃CL1 diffused within restricted confinement regions structured by the cortical actin cytoskeleton. These confinement regions sequestered CX₃CL1 from ADAM10, precluding their association. Disruption of the actin cytoskeleton reduced CX₃CL1 confinement and increased CX₃CL1–ADAM10 interactions, promoting the release of soluble chemokine. Our results demonstrate a novel role for the cytoskeleton in limiting membrane protein proteolysis, thereby regulating both cell surface levels and the release of soluble ligand.     

Fibroblast Growth Factor Receptor 1 Activation in Mammary Tumor Cells Promotes Macrophage Recruitment in a CX3CL1-Dependent Manner

Tumor formation is an extensive process requiring complex interactions that involve both tumor cell-intrinsic pathways and soluble mediators within the microenvironment. Tumor cells exploit the intrinsic functions of many soluble molecules, including chemokines and their receptors, to regulate pro-tumorigenic phenotypes that are required for growth and progression of the primary tumor. Previous studies have shown that activation of inducible FGFR1 (iFGFR1) in mammary epithelial cells resulted in increased proliferation, migration, and invasion in vitro and tumor formation in vivo. These studies also demonstrated that iFGFR1 activation stimulated recruitment of macrophages to the epithelium where macrophages contributed to iFGFR1-mediated epithelial cell proliferation and angiogenesis. The studies presented here further utilize this model to identify the mechanisms that regulate FGFR1-induced macrophage recruitment. Results from this study elucidate a novel role for the inflammatory chemokine CX3CL1 in FGFR1-induced macrophage migration. Specifically, we illustrate that activation of both the inducible FGFR1 construct in mouse mammary epithelial cells and endogenous FGFR in the triple negative breast cancer cell line, HS578T, leads to expression of the chemokine CX3CL1. Furthermore, we demonstrate that FGFR-induced CX3CL1 is sufficient to recruit CX3CR1-expressing macrophages in vitro. Finally, blocking CX3CR1 in vivo leads to decreased iFGFR1-induced macrophage recruitment, which correlates with decreased angiogenesis. While CX3CL1 is a known target of FGF signaling in the wound healing environment, these studies demonstrate that FGFR activation also leads to induction of CX3CL1 in a tumor setting. Furthermore, these results define a novel role for CX3CL1 in promoting macrophage recruitment during mammary tumor formation, suggesting that the CX3CL1/CX3CR1 axis may represent a potential therapeutic approach for targeting breast cancers associated with high levels of tumor-associated macrophages.     

Neuron–glia crosstalk in health and disease: fractalkine and CX3CR1 take centre stage

An essential aspect of normal brain function is the bidirectional interaction and communication between neurons and neighbouring glial cells. To this end, the brain has evolved ligand–receptor partnerships that facilitate crosstalk between different cell types. The chemokine, fractalkine (FKN), is expressed on neuronal cells, and its receptor, CX₃CR1, is predominantly expressed on microglia. This review focuses on several important functional roles for FKN/CX₃CR1 in both health and disease of the central nervous system. It has been posited that FKN is involved in microglial infiltration of the brain during development. Microglia, in turn, are implicated in the developmental synaptic pruning that occurs during brain maturation. The abundance of FKN on mature hippocampal neurons suggests a homeostatic non-inflammatory role in mechanisms of learning and memory. There is substantial evidence describing a role for FKN in hippocampal synaptic plasticity. FKN, on the one hand, appears to prevent excess microglial activation in the absence of injury while promoting activation of microglia and astrocytes during inflammatory episodes. Thus, FKN appears to be neuroprotective in some settings, whereas it contributes to neuronal damage in others. Many progressive neuroinflammatory disorders that are associated with increased microglial activation, such as Alzheimer''s disease, show disruption of the FKN/CX₃CR1 communication system. Thus, targeting CX₃CR1 receptor hyperactivation with specific antagonists in such neuroinflammatory conditions may eventually lead to novel neurotherapeutics.     

CXCR2 Macromolecular Complex in Pancreatic Cancer: A Potential Therapeutic Target in Tumor Growth

The signaling mediated by the chemokine receptor CXC chemokine receptor 2 (CXCR2) plays an important role in promoting the progression of many cancers, including pancreatic cancer, one of the most lethal human malignancies. CXCR2 possesses a consensus PSD-95/DlgA/ZO-1 (PDZ) motif at its carboxyl termini, which might interact with potential PDZ scaffold/adaptor proteins. We have previously reported that CXCR2 PDZ motif-mediated protein interaction is an important regulator for neutrophil functions. Here, using a series of biochemical assays, we demonstrate that CXCR2 is physically coupled to its downstream effector phospholipase C-β3 (PLC-β3) that is mediated by PDZ scaffold protein Na⁺/H⁺ exchange regulatory factor 1 (NHERF1) into a macromolecular signaling complex both in vitro and in pancreatic cancer cells. We also observe that disrupting the CXCR2 complex, by gene delivery or peptide delivery of exogenous CXCR2 C-tail, significantly inhibits the biologic functions of pancreatic cancer cells (i.e., proliferation and invasion) in a PDZ motif-dependent manner. In addition, using a human pancreatic tumor xenograft model, we show that gene delivery of CXCR2 C-tail sequence (containing the PDZ motif) by adeno-associated virus type 2 viral vector potently suppresses human pancreatic tumor growth in immunodeficient mice. In summary, our results suggest the existence of a physical and functional coupling of CXCR2 and PLC-β3 mediated through NHERF1, forming a macromolecular complex that is critical for efficient and specific CXCR2 signaling in pancreatic cancer progression. Disrupting this CXCR2 complex could represent a novel and effective treatment strategy against pancreatic cancer.     

Molecular Imaging of Pancreatic Duct Adenocarcinoma Using a Type 2 Cannabinoid Receptor-Targeted Near-Infrared Fluorescent Probe

Imaging probes targeting type 2 cannabinoid receptor (CB₂R) overexpressed in pancreatic duct adenocarcinoma (PDAC) tissue have the potential to improve early detection and surgical outcome of PDAC. The aim of our study was to evaluate the molecular imaging potential of a CB₂R-targeted near-infrared (NIR) fluorescent probe (NIR760-XLP6) for PDAC. CB₂R overexpression was observed in both PDAC patient tissues and various pancreatic cancer cell lines. In vitro fluorescence imaging indicated specific binding of NIR760-XLP6 to CB₂R in human PDAC PANC-1 cells. In a xenograft mouse tumor model, NIR760-XLP6 showed remarkable 50- (ex vivo) and 3.2-fold (in vivo) tumor to normal contrast enhancement with minimal liver and kidney uptake. In a PDAC lymph node metastasis model, significant signal contrast was observed in bilateral axillary lymph nodes with PDAC metastasis after injection of the probe. In conclusion, NIR760-XLP6 exhibits promising characteristics for imaging PDAC, and CB₂R appears to be an attractive target for PDAC imaging.     

Inhibition of Cell Proliferation and Growth of Pancreatic Cancer by Silencing of Carbohydrate Sulfotransferase 15 In Vitro and in a Xenograft Model

Chondroitin sulfate E (CS-E), a highly sulfated glycosaminoglycan, is known to promote tumor invasion and metastasis. Because the presence of CS-E is detected in both tumor and stromal cells in pancreatic ductal adenocarcinoma (PDAC), multistage involvement of CS-E in the development of PDAC has been considered. However, its involvement in the early stage of PDAC progression is still not fully understood. In this study, to clarify the direct role of CS-E in tumor, but not stromal, cells of PDAC, we focused on carbohydrate sulfotransferase 15 (CHST15), a specific enzyme that biosynthesizes CS-E, and investigated the effects of the CHST15 siRNA on tumor cell proliferation in vitro and growth in vivo. CHST15 mRNA is highly expressed in the human pancreatic cancer cell lines PANC-1, MIA PaCa-2, Capan-1 and Capan-2. CHST15 siRNA significantly inhibited the expression of CHST15 mRNA in these four cells in vitro. Silencing of the CHST15 gene in the cells was associated with significant reduction of proliferation and up-regulation of the cell cycle inhibitor-related gene p21^CIP1/WAF1. In a subcutaneous xenograft tumor model of PANC-1 in nude mice, a single intratumoral injection of CHST15 siRNA almost completely suppressed tumor growth. Reduced CHST15 protein signals associated with tumor necrosis were observed with the treatment with CHST15 siRNA. These results provide evidence of the direct action of CHST15 on the proliferation of pancreatic tumor cells partly through the p21^CIP1/WAF1 pathway. Thus, CHST15-CS-E axis-mediated tumor cell proliferation could be a novel therapeutic target in the early stage of PDAC progression.     

Membrane proteomic analysis of pancreatic cancer cells

Background  

Pancreatic cancer is one of the most aggressive human tumors due to its high potential of local invasion and metastasis. The aim of this study was to characterize the membrane proteomes of pancreatic ductal adenocarcinoma (PDAC) cells of primary and metastatic origins, and to identify potential target proteins related to metastasis of pancreatic cancer.     

Molecular mechanisms of perineural invasion,a forgotten pathway of dissemination and metastasis

Invasion and metastasis are key components of cancer progression. Inflammatory mediators, including cytokines and chemokines, can facilitate tumor dissemination. A distinct and largely forgotten path is perineural invasion (PNI), defined as the presence of cancer cells in the perinerium space. PNI is frequently used by many human carcinomas, in particular by pancreas and prostate cancer, and is associated with tumor recurrence and pain in advanced patients. Neurotrophic factors have been identified as molecular determinants of PNI. A role for chemokines in this process has been proposed; the chemokine CX3CL1/Fractalkine attracts receptor positive pancreatic tumor cells to disseminate along peripheral nerves. Better understanding of the neurotropism of malignant cells and of the clinical significance of PNI would help the design of innovative strategies for the control of tumor dissemination and pain in cancer patients.     

Spinal CX3CL1/CX3CR1 May Not Directly Participate in the Development of Morphine Tolerance in Rats

CX3CL1 (fractalkine), the sole member of chemokine CX3C family, is implicated in inflammatory and neuropathic pain via activating its receptor CX3CR1 on neural cells in spinal cord. However, it has not been fully elucidated whether CX3CL1 or CX3CR1 contributes to the development of morphine tolerance. In this study, we found that chronic morphine exposure did not alter the expressions of CX3CL1 and CX3CR1 in spinal cord. And neither exogenous CX3CL1 nor CX3CR1 inhibitor could affect the development of morphine tolerance. The cellular localizations of spinal CX3CL1 and CX3CR1 changed from neuron and microglia, respectively, to all the neural cells during the development of morphine tolerance. A microarray profiling revealed that 15 members of chemokine family excluding CX3CL1 and CX3CR1 were up-regulated in morphine-treated rats. Our study provides evidence that spinal CX3CL1 and CX3CR1 may not be involved in the development of morphine tolerance directly.

     

Sonic advance: CCN1 regulates sonic hedgehog in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the fifth leading cause of cancer internationally. As the precise molecular pathways that regulate pancreatic cancer are incompletely understood, appropriate targets for drug intervention remain elusive. It is being increasingly appreciated that the cellular microenvironment plays an important role in driving tumor growth and metastasis. CCN1, a member of the CCN family of secreted matricellular proteins, is overexpressed in pancreatic cancer, and may represent a novel target for therapy. Sonic hedgehog (SHh) is responsible for PDAC cell proliferation, epithelial-mesenchymal transition (EMT), maintenance of cancer stemness, migration, invasion, and metastatic growth; in a recent report, it was shown that CCN1 is a potent regulator of SHh expression via Notch-1. CCN1 activity was mediated, at least in part, through altering proteosome activity. These results suggest that CCN1 may be an ideal target for treating PDAC.     

DEspR Roles in Tumor Vasculo-Angiogenesis,Invasiveness, CSC-Survival and Anoikis Resistance: A ‘Common Receptor Coordinator’ Paradigm

A priori, a common receptor induced in tumor microvessels, cancer cells and cancer stem-like cells (CSCs) that is involved in tumor angiogenesis, invasiveness, and CSC anoikis resistance and survival, could underlie contemporaneous coordination of these events rather than assume stochasticity. Here we show that functional analysis of the dual endothelin1/VEGFsignal peptide receptor, DEspR, (formerly named Dear, Chr.4q31.2) supports the putative common receptor paradigm in pancreatic ductal adenocarcinoma (PDAC) and glioblastoma (GBM) selected for their invasiveness, CD133+CSCs, and polar angiogenic features. Unlike normal tissue, DEspR is detected in PDAC and GBM microvessels, tumor cells, and CSCs isolated from PDAC-Panc1 and GBM-U87 cells. DEspR-inhibition decreased angiogenesis, invasiveness, CSC-survival and anoikis resistance in vitro, and decreased Panc1-CSC and U87-CSC xenograft tumor growth, vasculo-angiogenesis and invasiveness in nude^nu/nu rats, suggesting that DEspR activation would coordinate these tumor progression events. As an accessible, cell-surface ‘common receptor coordinator’, DEspR-inhibition defines a novel targeted-therapy paradigm for pancreatic cancer and glioblastoma.     

Long noncoding RNA DLEU1 aggravates pancreatic ductal adenocarcinoma carcinogenesis via the miR-381/CXCR4 axis

Recent evidence has highlighted that long noncoding RNAs (lncRNA) are associated with many diseases, particularly cancer. However, current understanding of the lncRNA deleted in lymphocytic leukemia 1 (DLEU1) in pancreatic ductal adenocarcinoma (PDAC) remains limited. Our studies indicated that the DLEU1 expression level was upregulated in PDAC tissue samples compared with adjacent normal tissue. Moreover, the aberrant overexpression of DLEU1 indicated poor prognosis of patients with PDAC. Loss-of-function experiments revealed that DLEU1 knockdown inhibited the proliferation, migration, and invasion of PDAC cells in vitro and decreased tumor growth in vivo. Bioinformatics analysis predicted that miR-381 potentially targeted the DLEU1 3′-untranslated region (UTR), suggesting an interaction between miR-381 and DLEU1. Furthermore, miR-381 also targeted the chemokine receptor-4 (CXCR4) messenger RNA 3′-UTR, which was validated by luciferase reporter assay. Taken together, our study demonstrated the oncogenic role of DLEU1 in clinical PDAC specimens and cellular experiments, showing the potential involvement of DLEU1/miR-381/CXCR4 pathway. These results provide novel insight into PDAC tumorigenesis.