Novel circularRNA circ-0047078 promotes pancreatic ductal adenocarcinoma progression through mircoRNA miR-11181- Chemokine (C-X-C motif) Ligand 12/Melanoma Cell Adhesion Molecule/Regulator of G-protein signaling 16 pathway

BACKGROUND

Circular RNAs (circRNAs), new members of the noncoding RNA family, have been reported to participate in various pathological conditions, especially cancer. Pancreatic ductal adenocarcinoma (PDAC), as one of the most aggressive human solid tumors, is still with a low surgical cure rate. Exploring the role of circRNAs in PDAC is meaningful, and may offer a new therapeutic approach for PDAC.

METHODS AND RESULTS

Competing endogenous RNA (ceRNA) microarray revealed that circ-0047078 was highly expressed in pancreatic ductal adenocarcinoma (PDAC) tissues compared with adjacent normal tissues, and the differential expression was further confirmed by PCR in both tissues and cell lines. Cell functional assays including cell counting kit-8 (CCK-8) assay, transwell invasion assay, flow cytometry and caspase activity assay demonstrated that circ-0047078 was positively correlated with the proliferation and invasion but negatively correlated with the apoptosis of CFPAC-1 cells. Circ-0047078 knockdown led to miR-11181, CXCL12 and MCAM downregulation and RGS16 upregulation, and the effect of circ-0047078 knockdown on CFPAC-1 cell behavior change can be reversed by miR-11181 mimic. Moreover, clinicopathological analysis indicated that circ-0047078 expression level was positively correlated with lymphatic metastasis and perineural invasion. In addition, knockdown of Chemokine (C-X-C motif) Ligand 12 (CXCL12) alone decreased proliferation, invasion, but increased apoptosis of CFPAC-1 cells, and raised the activity of caspase-3, caspase-8 and caspase-9 activity. Knockdown of Melanoma Cell Adhesion Molecule (MCAM) alone decreased invasion and increased apoptosis of CFPAC-1 cells, and both caspase-3 and caspase-9 activity increased, but no obvious change observed on caspase-8, and also no significant effect on CFPAC-1 cells proliferation. Knockdown of Regulator of G-protein signaling 16 (RGS16) alone increased invasion of CFPAC-1 cells, but had no significant effect on proliferation and apoptosis, of course, no obvious change on the activity of caspase-3, caspase-8 and caspase-9 had been observed.

CONCLUSIONS

In conclusion, circ-0047078 plays a role in promoting PDAC via miR-11181 and then via CXCL12, MCAM and RGS16. Circ-0047078 may serve as a promising novel therapeutic target for PDAC patients.

[MiR-372-5p regulates PI3K/AKT/CXCL12 signaling pathway by targeting PTEN to promote colorectal cancer cell metastasis]

OBJECTIVE

To investigate whether miR-372-5p regulates PI3K/AKT/CXCL12 signaling pathway by targeting PTEN to promote metastasis of colorectal cancer cells.

METHODS

We detected the differential expression of miR-372-5p using RT-qRCR in colorectal cancer and adjacent tissues, colorectal cancer cells and normal intestinal epithelial cells. Bioinformatic analysis and double luciferase assay were performed for verification of the targeting relationship between miR-372-5p and PTEN. Western blotting was used to assess the effects of transfection with miR-372-5p inhibitor and miR-372-5p mimics alone, co-transfection with miR-372-5p inhibitor and si-PTEN, and co-transfection with miR-372-5p mimics and PI3K inhibitor on the expressions of PTEN and CXCL12 and the activation of PI3K/AKT signal pathway; Transwell assay and scratch assay were used to examine the changes in the migration ability of the transfected cells, the cells co-transfected with miR-372-5p mimics and si-CXCL12, and the cells treated with conditioned medium from HCT116 cells transfected with miR-372-5p mimics.

RESULTS

The expression of miR-372-5p was significantly higher in colorectal cancer tissues than in adjacent tissues, and higher in HCT116 and SW620 cells than in NCM460 cells (P < 0.01). Double luciferase assay confirmed that PTEN was a potential target gene of miR-372-5p (P < 0.05). Transfection of HCT116 cells with miR-372-5p mimics obviously decreased PTEN protein expression, increase CXCL12 expression and the phosphorylation level of AKT, and lowered the cell migration ability, while transfection with miR-372-5p inhibitor produced the opposite effects (P < 0.05); si-PTEN obviously neutralized the effect of miR-372-5p inhibitor (P < 0.01). PI3K inhibitor significantly decreased CXCL12 expression and inhibited the cell migration (P < 0.05), and this effect was mitigated by miR-372-5p mimics (P < 0.01). Treatment with the conditioned medium from HCT116 cells transfected with miR-372-5p mimics significantly enhanced the migration ability of NCM460 cells, and this effect was suppressed by transfection with si-CXCL12 (P < 0.01).

CONCLUSION

MiR-372-5p activates PI3K/AKT signaling pathway by targeting PTEN and up-regulates CXCL12 expression to promoting metastasis of colorectal cancer cells.

CXCL12 derived from CD248-expressing cancer-associated fibroblasts mediates M2-polarized macrophages to promote nonsmall cell lung cancer progression

Nonsmall cell lung cancer (NSCLC) is among the most prevalent malignant tumours threatening human health. In the tumour microenvironment (TME), cancer-associated fibroblasts (CAFs) induce M2-polarized macrophages, which strongly regulate tumour progression. However, little is known about the association between CAFs and M2 macrophages. CD248 is a transmembrane glycoprotein found in several cancer cells, tumour stromal cells, and pericytes. Here, we isolated CAFs from tumour tissues of NSCLC patients to detect the relationship between CD248 expression and patient prognosis. We knocked down the expression of CD248 on CAFs to detect CXCL12 secretion and macrophage polarization. We then examined the effects of CD248-expressing CAF-induced M2 macrophage polarization to promote NSCLC progression in vitro and in vivo. We found that CD248 is expressed mainly in NSCLC-derived CAFs and that the expression of CD248 correlates with poor patient prognosis. Blocking CXCL12 receptor (CXCR4) drastically decreased M2 macrophage chemotaxis. CD248 promotes CAFs secreting CXCL12 to mediate M2-polarized macrophages to promote NSCLC progression both in vitro and in vivo. Collectively, our data suggest that CD248-positive CAFs induce NSCLC progression by mediating M2-polarized macrophages.

Low Expression Levels of CXCL12, CXCR4, and CXCR 7 in Peripheral Blood and Decidual Tissues are Associated with Miscarriage in Women

Miscarriage can cause significant physical and psychological harm to women. The stromal cell-derived factor 1 (SDF-1, also known as CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) and C-X-C motif chemokine receptor 7 (CXCR7) axis can promote the proliferation and invasion of trophoblast cells in early pregnancy, and maintain immune tolerance at the maternal-fetal interface to aid with pregnancy success. From our findings, the serum CXCL12 level of women who have miscarried (n = 25) was significantly lower than that of healthy early pregnancy women (n = 20) by ELISA (P < .001). Additionally, CXCL12 levels in normal non-pregnant women (n = 20) were significantly lower than those in early pregnancy women (P < .001) and women who have miscarried (P < .001). Quantitative real-time PCR detected no significant difference in the mRNA transcription levels of CXCR4 and CXCR7 in the decidua tissues of women with early pregnancy (n = 20) and miscarriage (n = 20) (P = .724, P = .281, respectively). However, Western blot and immunohistochemistry of CXCR4 and CXCR7 in decidual tissue of women who have miscarried (n = 20) were significantly lower than those in early pregnancy women (n = 20) (P < .05 for both). Therefore, we believe that the increased serum CXCL12 levels in pregnant offspring may benefit normal pregnancy maintenance. The low level of CXCL12 in peripheral blood and the low expression of CXCR4 and CXCR7 proteins in decidua may be associated with the occurrence of early spontaneous abortion, and the clinical application value of serum CXCL12 in predicting adverse pregnancy outcomes is worth further exploring.

Interaction between mesenchymal stem cells and myoblasts in the context of facioscapulohumeral muscular dystrophy contributes to the disease phenotype

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disease associated with ectopic expression of the DUX4 gene in skeletal muscle. Muscle degeneration in FSHD is accompanied by muscle tissue replacement with fat and connective tissue. Expression of DUX4 in myoblasts stimulates mesenchymal stem cells (MSC) migration via the CXCR4-CXCL12 axis. MSCs participate in adipose and connective tissue formation and can contribute to fibrosis. Here we studied the interaction between myoblasts and MSCs and the consequences of this interaction in the FSHD context. We used cell motility assays and coculture of MSCs with myoblasts to study their mutual effects on cell migration, differentiation, proliferation, and extracellular matrix formation. The growth medium conditioned by FSHD myoblasts stimulated MSCs migration 1.6-fold (p < 0.04) compared to nonconditioned medium. Blocking the CXCL12-CXCR4 axis with the CXCR4 inhibitor (AMD3100) or neutralizing antibodies to CXCL12 abolished this effect. FSHD myoblasts stimulated MSC proliferation 1.5-2 times (p < 0.05) compared to control myoblasts, while the presence of MSCs impaired myoblast differentiation. Under inflammatory conditions, medium conditioned by FSHD myoblasts stimulated collagen secretion by MSCs 2.2-fold as compared to the nonconditioned medium, p < 0.03. FSHD myoblasts attract MSCs via the CXCL12-CXCR4 axis, stimulate MSC proliferation and collagen secretion by MSCs. Interaction between MSCs and FSHD myoblasts accounts for several important aspects of FSHD pathophysiology. The CXCL12-CXCR4 axis may serve as a potential target to improve the state of the diseased muscles.

The potential role of circulating exosomes in protecting myocardial injury in acute myocardial infarction via regulating miR-190a-3p/CXCR4/CXCL12 pathway

Exosomes of different origins have been found to be protective against ischemic-induced myocardial injury. This study examined the protective effects of circulating exosomes in the mice model of acute myocardial infarction (AMI) and explored the underlying molecular mechanisms. The effects of exosomes on myocardial injury were assessed in the AMI mice model. The in vivo studies showed that circulating exosomes reduced the infarcted size, improved the morphology of heart tissues and also reduced apoptosis of the heart tissues. In addition, the model mice showed an increase in the CD34 + /VEGFR2 + cell population and CD31, CXCR4 and CXCL12 expression after exosomes treatment. MiR-190a-3p was significantly down-regulated in the exosomes derived from the culture medium of hypoxia-treated human cardiomyocytes (HCMs). Further analysis revealed that miR-190a-3p could physically interact with CXCR4/CXCL12 by targeting the respective 3'UTRs. These exosomes could up-regulated CXCR4 and CXCL12 expression in the EPCs; in addition, miR-190a-3p mimics repressed CXCR4/CXCL12 expression in EPCs, while its inhibitor had opposite effects. The in vitro functional assays showed that miR-190a-3p overexpression suppressed the cell viability, proliferation, migration, adhesion and tube formation of EPCs; while miR-190a-3p inhibitor had the opposite effects; exosomes derived from the culture medium of hypoxia-treated HCMs exhibited similar actions of miR-190a-3p inhibitor. Moreover, miR-190a-3p was down-regulated in exosomes from serum in the AMI group when compared to that from sham group. Treatment with exosomes from serum in the AMI group promoted cell proliferation, migration, adhesion and tube formation of EPCs when compared to that in the sham group. More importantly, IT1t attenuated the enhanced effects of miR-190a-3p inhibition on EPC proliferation, migration, adhesion and tube formation. In conclusion, circulating exosomes exerted protective effects on myocardial injury in the AMI mice model, and down-regulation of miR-190a-3p in the circulating exosomes may exert protective effects against myocardial injury. Hypoxia induced the downregulation of miR-190a-3p in the culture medium of HCMs, and the mechanistic investigations indicated that exosomes of hypoxia-conditioned HCM culture medium promoted the cell viability, proliferation, migration, adhesion and tube formation of EPCs via regulating miR-190a-3p/CXCR4/CXCL12 pathway.

Differences in chemotaxis of human mesenchymal stem cells and cervical cancer cells

In the last decade, there has been a rapid expansion in tumor targeted therapy using mesenchymal stem cells (MSCs) based on their unique tropism towards cancer cells. Despite similarities in morphology, immunophenotype, and differential potent in vitro, MSCs originated from different tissues do not necessarily have equivalent biological behaviors. It is important to screen the most chemotactic MSCs to cancer cells. In this study, different MSCs were isolated from various human tissues including adipose, umbilical cord, amniotic membrane, and chorion. The chemotaxis of human MSCs to cervical cancer cells was measured by CCK-8, ELISA and Transwell invasion assays. Western blotting was performed to explore the underlying mechanisms. MSCs derived from distinct sources can be differently recruited to cervical cancer cells, among which chorion-derived MSC (CD-MSC) possessed the strongest tropic capacity. CXCL12 was found to be highly secreted by cervical cancer cells, in parallel with the expression of CXCR4 in all MSCs. CD-MSC displayed the highest level of CXCR4. These results indicated that CXCL12/CXCR4 pathway contributed to the different chemotaxis to cervical cancer cells of each MSCs. This study proposed that CD-MSC with the highest CXCR4 expression is a promising therapeutic vehicle for targeted therapy in cervical cancer.

CXCL12 inhibits hair growth through CXCR4

CXCL12 and its receptors, which are highly expressed in the skin, are associated with various cutaneous diseases, including androgenic alopecia. However, their expression and role during the hair cycle are unknown. This study aims to investigate the expression of CXCL12 and its receptor, CXCR4, in the vicinity of hair follicles and their effect on hair growth. CXCL12 was highly expressed in dermal fibroblasts (DFs) and its level was elevated throughout the catagen and telogen phases of the hair cycle. CXCR4 is expressed in the dermal papilla (DP) and outer root sheath (ORS). In hair organ culture, hair loss was induced by recombinant CXCL12 therapy, which delayed the telogen-to-anagen transition and decreased hair length. In contrast, the suppression of CXCL12 using a neutralizing antibody and siRNA triggered the telogen-to-anagen transition and increased hair length in hair organ culture. Neutralization of CXCR7, one of the two receptors for CXCL12, only slightly affected hair growth. However, inhibition of CXCR4, the other receptor for CXCL12, increased hair growth to a considerable extent. In addition, in hair organ culture, the conditioned medium from DFs with CXCL12 siRNA considerably increased the hair length and induced proliferation of DP and ORS cells. CXCL12, through CXCR4 activation, increased STAT3 and STAT5 phosphorylation in DP and ORS cells. In contrast, blocking CXCL12 and CXCR4 decreased the phosphorylation of STAT3 and STAT5. In summary, these findings suggest that CXCL12 inhibits hair growth via the CXCR4/STAT signaling pathway and that CXCL12/CXCR4 pathway inhibitors are a promising treatment option for hair growth.

PRMT6/LMNA/CXCL12 signaling pathway regulated the osteo/odontogenic differentiation ability in dental stem cells isolated from apical papilla

Tooth loss and maxillofacial bone defect are common diseases, which seriously affect people's health. Effective tooth and maxillofacial bone tissue regeneration is a key problem that need to be solved. In the present study, we investigate the role of PRMT6 in osteo/odontogenic differentiation and migration capacity by using SCAPs. Our results showed that knockdown of PRMT6 promoted the osteo/odontogenic differentiation compared with the control group, as detected by alkaline phosphatase activity, alizarin red staining, and the indicators of osteo/odontogenic differentiation measured by Western blot. In addition, overexpression of PRMT6 inhibited the osteo/odontogenic differentiation potentials of SCAPs. Then, knockdown of PRMT6 promoted the migration ability and overexpression of PRMT6 inhibited the migration ability in SCAPs. Mechanically, we discovered that the depletion of PRMT6 promoted the expression of CXCL12 by decreasing H3R2 methylation in the promoter region of CXCL12. In addition, PRMT6 formed a protein complex with LMNA, a nuclear structural protein. Depletion of LMNA inhibited the osteo/odontogenic differentiation and CXCL12 expression and increased the intranucleus PRMT6 in SCAPs. To sum up, PRMT6 might inhibit the osteo/odontogenic differentiation and migration ability of SCAPs via inhibiting CXCL12. And LMNA might be a negative regulator of PRMT6. It is suggested that PRMT6 may be a key target for SCAP-mediated bone and tooth tissue regeneration.

Positive effects of selenium supplementation on selenoprotein S expression and cytokine status in a murine model of acute liver injury

BACKGROUND

It is a consensus that selenomethionine (SeMet) can protect liver from damage, but the immune mechanism of SeMet in acute liver injury (ALI) is still unclear. This study aims to investigate the protective effects of SeMet against ALI and to elucidate the possible immune mechanism.

METHODS

Firstly, the role of SeMet in CCl4-induced ALI mice was investigated through survival rate, serum ALT and AST, liver necrosis and apoptosis analysis. The expression and secretion of inflammatory cytokines and chemokines in the liver and serum of CCl4-induced ALI mice were analyzed by qRT-PCR and ELISA. Then the immune cell phenotypes were analyzed by flow cytometry and confocal imaging. In addition, MDSCs depletion, CXCL12/CXCR4 axis blocking and selenoprotein S (SELENOS) knockdown assays were used to reveal the immune mechanism of SeMet.

RESULTS

We found that SeMet prolonged survival rate, decreased the serum ALT and AST, alleviated liver necrosis and inhibited hepatocytes apoptosis. Prospective, SeMet decreased the expression of IL-6 and TNF-α, and increased the expression of IL-10. Interestingly, SeMet decreased the expression of MCP-1, while increased the expression of CXCL12. The immune analysis showed that SeMet decreased the activation of T cells through promoting MDSCs accumulation mediated by CXCL12/CXCR4 axis. Furthermore, SeMet increased SELENOS expression in vivo, and knockdown of SELENOS effectively abolished the protective effect of SeMet during ALI.

CONCLUSION

This study demonstrates that SeMet alleviates CCl4-induced ALI by promoting MDSCs accumulation through SELENOS mediated CXCL12/CXCR4 axis. Therefore, our study infers that selenium intake may be as a new therapeutic option for management of inflammation-mediated liver injury.

Myometrial-derived CXCL12 promotes lipopolysaccharide induced preterm labour by regulating macrophage migration, polarization and function in mice

Preterm birth is a major contributor to neonatal mortality and morbidity. Infection results in elevation of inflammation-related cytokines followed by infiltration of immune cells into gestational tissue. CXCL12 levels are elevated in preterm birth indicating it may have a role in preterm labour (PTL); however, the pathophysiological correlations between CXCL12/CXCR4 signalling and premature labour are poorly understood. In this study, PTL was induced using lipopolysaccharide (LPS) in a murine model. LPS induced CXCL12 RNA and protein levels significantly and specifically in myometrium compared with controls (3-fold and 3.5-fold respectively). Highest levels were found just before the start of labour. LPS also enhanced the infiltration of neutrophils, macrophages and T cells, and induced macrophage M1 polarization. In vitro studies showed that condition medium from LPS-treated primary smooth muscle cells (SMC) induced macrophage migration, M1 polarization and upregulated inflammation-related cytokines such as interleukin (IL)-1, IL-6 and tumor necrosis factor alpha (TNF-α). AMD3100 treatment in pregnant mice led to a significant decrease in the rate of PTL (70%), prolonged pregnancy duration and suppressed macrophage infiltration into gestation tissue by 2.5-fold. Further, in-vitro treatment of SMC by AMD3100 suppressed the macrophage migration, decreased polarization and downregulated IL-1, IL-6 and TNF-α expression. LPS treatment in pregnant mice induced PTL by increasing myometrial CXCL12, which recruits immune cells that in turn produce inflammation-related cytokines. These effects stimulated by LPS were completely reversed by AMD3100 through blocking of CXCL12/CXCR4 signalling. Thus, the CXCL12/CXCR4 axis presents an excellent target for preventing infection and inflammation-related PTL.

CPEB3, an RNA-Binding Protein, Modulates the Behavior of Endometriosis-Derived Stromal Cells via Regulating CXCL12

Endometriosis is a benign gynecological disease sharing several features with malignant tumor. Cytoplasmic polyadenylation element-binding protein 3 (CPEB3), a potential target of miR-21-5p, is downregulated in endometriotic specimens. However, the function of CPEB3 in endometriosis is elusive. In this study, in cultured primary human endometrial stromal cells (ESCs), the overexpression and inhibition of CPEB3 were achieved by transduction of adenovirus-mediated CPEB3 overexpressed plasmid and shRNA, respectively. Functional analysis uncovered that upregulated CPEB3 reduced cell viability and arrested cell cycle entry. The expression of cyclin D1 and c-Myc was decreased after CPEB3 overexpression. Overexpression of CPEB3 facilitated ESC apoptotic potential, accompanied by increased Bax, cleaved-caspase 3 and cleaved-caspase 9, and reduced Bcl2. Moreover, elevated CPEB3 weakened migration and invasion abilities of ESCs. CPEB3 overexpression also reduced the expression of fibronectin and vimentin and the activities of matrix metalloproteinase (MMP)-9 and MMP-2. Interestingly, these effects were counteracted by CPEB3 inhibition. Furthermore, CPEB3 controlled the protein level of CXCL12, a homeostatic chemokine. CXCL12 elevation partially reversed the effects of CPEB3 on inhibiting ESC proliferation, migration and invasion, and promoting apoptosis. Based on these findings, it seems possible that CPEB3, as a critical player, attenuated the progression of endometriosis through repressing CXCL12 expression.

Chemokine therapy for anal sphincter injury in a rat model: a pilot study

INTRODUCTION AND HYPOTHESIS

To determine whether delayed administration of CXCL12 alters anorectal manometric pressures and histology in rats following anal sphincterotomy compared to primary surgical repair alone.

METHODS

Adult female rats were divided into three groups: A, a control group that did not undergo surgery; B, anal sphincterotomy with primary surgical repair; C, anal sphincterotomy with primary surgical repair and intra-sphincteric injection of CXCL12 at 6 weeks post-injury. All rats underwent anal manometry measurements at baseline and at 6 and 12 weeks post-injury. Histologic analysis of the anal sphincters was also performed.

RESULTS

At baseline and 6 weeks, there were no statistically significant differences among D, T_max and P∆ of Groups A, B and C. At 12-week manometry, the total duration of contractions on anal manometry was significantly less in Group C compared to Groups A and B (3.65, 5.5, 5.3 p < 0.01) as was time to peak of contraction at 12 weeks (1.6, 2.1, 3.1, p < 0.01); however, group C had a significantly higher P∆ at 12 weeks compared to Groups A and B (2.25, 1.4, 0.34, p < 0.01). There were no statistically significant differences in the ratio of muscle to collagen at the site of injury; however, muscle fibers were significantly smaller in group C and less per bundle than the other groups.

CONCLUSIONS

Administration of chemokine therapy at 6 weeks post-repair using CXCL12 enhanced the magnitude of anal sphincter contractions in a rat model of anal sphincter injury but decreased overall duration of contraction. Increased anal sphincter contraction magnitude was not explained by histologic differences in explanted specimens.

Downregulation of lncRNA NEAT1 alleviates sepsis-induced acute kidney injury

Sepsis-induced acute kidney injury (AKI) is one of the important causes of increased mortality in sepsis patients. Long non-coding RNA (lncRNA) is believed to play a vital function in the progression of AKI. However, the mechanism of nuclear enriched abundant transcript 1 (NEAT1) has not been fully elucidated. NEAT1 was overexpressed and miR-22-3p was underexpressed in sepsis patients and lipopolysaccharide (LPS)-induced AKI cell models. Knockdown of NEAT1 could promote viability and suppress apoptosis and the inflammatory response in LPS-induced HK2 cells. MiR-22-3p could be sponged by NEAT1, and its inhibitor reversed the inhibition effect of NEAT1 silencing on LPS-induced HK2 cell injury. CXCL12 could be targeted by miR-22-3p, and its overexpression reversed the suppression effect of miR-22-3p on LPS-induced HK2 cell injury. Silenced NEAT1 could restrain the activity of the NF-κB signaling pathway, and miR-22-3p inhibitor or CXCL12 overexpression could reverse this effect. In addition, NEAT1 knockdown alleviated the inflammation response of cecal ligation and puncture (CLP) mouse models. In summary, our data showed that NEAT1 promoted LPS-induced HK2 cell injury via regulating the miR-22-3p/CXCL12/NF-κB signaling pathway, suggesting that NEAT1 knockdown might be a potential pathway for alleviating sepsis-induced AKI.

A Scintillation Proximity Assay for Real-Time Kinetic Analysis of Chemokine-Chemokine Receptor Interactions

Chemokine receptors are extensively involved in a broad range of physiological and pathological processes, making them attractive drug targets. However, despite considerable efforts, there are very few approved drugs targeting this class of seven transmembrane domain receptors to date. In recent years, the importance of including binding kinetics in drug discovery campaigns was emphasized. Therefore, kinetic insight into chemokine-chemokine receptor interactions could help to address this issue. Moreover, it could additionally deepen our understanding of the selectivity and promiscuity of the chemokine-chemokine receptor network. Here, we describe the application, optimization and validation of a homogenous Scintillation Proximity Assay (SPA) for real-time kinetic profiling of chemokine-chemokine receptor interactions on the example of ACKR3 and CXCL12. The principle of the SPA is the detection of radioligand binding to receptors reconstituted into nanodiscs by scintillation light. No receptor modifications are required. The nanodiscs provide a native-like environment for receptors and allow for full control over bilayer composition and size. The continuous assay format enables the monitoring of binding reactions in real-time, and directly accounts for non-specific binding and potential artefacts. Minor adaptations additionally facilitate the determination of equilibrium binding metrics, making the assay a versatile tool for the study of receptor-ligand interactions.

MiR-126 downregulates CXCL12 expression in intestinal epithelial cells to suppress the recruitment and function of macrophages and tumorigenesis in a murine model of colitis-associated colorectal cancer

Inflammatory bowel disease, characterised by chronic relapsing‐remitting colitis, is a significant risk factor for colorectal cancer (CRC). Previously, we showed that miR‐126 functions as a tumour suppressor in CRC and is inversely correlated with tumour proliferation, metastasis and patient prognosis. In the current study, we documented a protective role for miR‐126 in colitis‐associated CRC (CAC) and its underlying mechanism. We detected downregulated miR‐126 expression during colorectal tumorigenesis in the mouse CAC model and in specimens from patients with CRC. The deficiency of miR‐126 in intestinal epithelial cells (IECs) exacerbated tumorigenesis in mice. We identified CXCL12 as a direct target of miR‐126 in inhibiting the development of colitis and CAC. Moreover, miR‐126 regulated the recruitment of macrophages via CXCL12 and decreased the levels of proinflammatory cytokines (IL‐6, IL‐12 and IL‐23). In addition, IL‐6 secreted by macrophages, which were regulated by cocultured transfected CRC cells, altered the proliferation and migration of colon cells. Our data suggest that miR‐126 exerts an antitumour effect on CAC by regulating the crosstalk between IECs and macrophages via CXCL12‐IL‐6 signalling. Our study contributes to the understanding of cancer progression and suggests miR‐126 as a potential therapy for CRC.

Enhanced CXCL12/CXCR4 signaling increases tumor progression in radiation‑resistant pancreatic cancer

Pancreatic cancer (PaCa) exhibits one of the poorest prognoses among all gastrointestinal cancers due to the rapid development of treatment resistance, which renders chemotherapy and radiotherapy no longer effective. However, the mechanisms through which PaCa becomes resistant to radiotherapy are unknown. Here, we established radiation‑resistant PaCa cell lines to investigate the factors involved in radiation resistance. The role of the C‑X‑C motif chemokine ligand 12 (CXCL12)/C‑X‑C chemokine receptor type 4 (CXCR4) axis in radiation resistance in PaCa and the effects of a CXCR4 antagonist on radiation‑resistant PaCa cell lines were investigated. As confirmed by immunofluorescence staining, reverse transcription quantitative polymerase chain reaction, and western blotting, the expression of CXCR4 was higher in radiation‑resistant PaCa cell lines than that noted in normal PaCa cell lines. The invasion ability of radiation‑resistant PaCa cell lines was greater than that of normal cell lines and was enhanced by CXCL12 treatment and coculture with fibroblasts; this enhanced invasion ability was suppressed by the CXCR4 antagonist AMD070. Irradiation after treatment with the CXCR4 antagonist suppressed the colonization of radiation‑resistant PaCa cell lines. In conclusion, the CXCL12/CXCR4 axis may be involved in the radiation resistance of PaCa. These findings may facilitate the development of novel treatments for PaCa.

Research progress of the CXCR4 mechanism in Alzheimer's disease

Alzheimer's disease (AD) is a degenerative brain disease with complex clinical manifestations and pathogeneses such as abnormal deposition of beta-amyloid protein and inflammation caused by the excessive activation of microglia. CXC motif chemokine receptor type 4 (CXCR4) is a type of G protein-coupled receptor that binds to CXC motif ligand 12 (CXCL12) to activate downstream signaling pathways, such as the Janus kinase/signal transducer and activator of transcription and the renin-angiotensin system (Ras)/RAF proto-oncogene serine (Raf)/mitogen-activated protein kinase/extracellular-regulated protein kinase; most of these signaling pathways are involved in inflammatory responses. CXCR4 is highly expressed in the microglia and astrocytes; this might be one of the important causes of inflammation caused by microglia and astrocytes. In this review, we summarize the mechanism and therapeutics of AD, the structures of CXCR4 and the CXCL12 ligand, and the mechanisms of CXCR4/CXCL12 that are involved in the occurrence and development of AD. The possible treatment of AD through microglia and astrocytes is also discussed, with the aim of providing a new method for the treatment of AD.

C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 7(CXCR7) regulates epithelial-mesenchymal transition process and promotes the metastasis of esophageal cancer by activating signal transducer and activator of transcription 3 (STAT3) pathway

Esophageal cancer is a malignant tumor of the digestive system that is prone to metastasis. Chemokines and their receptors act an essential role in the occurrence and development of tumors. Here, we investigated the regulatory mechanism of CXCL12/CXCR7 in the growth and metastasis of esophageal cancer. CXCR7 was found highly expressed in clinical tissues and cells of esophageal cancer. Knockdown of CXCR7 inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) process of esophageal cancer cells. The knockdown of chemokine CXCL12 also inhibited the expression of EMT-related proteins and the mesenchymal morphology changes of esophageal cancer cells, but the knockdown of C-X-C motif chemokine receptor 4 (CXCR4) had no such effect. Furthermore, the knockdown of CXCR7 attenuated the enhanced EMT process induced by CXCL12 overexpression, while the knockdown of CXCR4 cannot inhibit this process. In addition, overexpressed CXCL12/CXCR7 activated the downstream STAT3 pathway, but had little effect on the extracellular regulated protein kinase (ERK) or serine-threonine kinase (AKT) pathways. Inhibition of the STAT3 pathway using AZD9150 weakened the accelerated effects of CXCL12/CXCR7 on the growth and metastasis of esophageal cancer in vitro and in vivo. In conclusion, our research revealed that CXCL12/CXCR7 regulates EMT and other malignant processes by activating the STAT3 pathway to accelerate the growth and metastasis of esophageal cancer.

Tumor promoting effect of circ_002172 associates with induced immune escape in breast cancer via the miR-296-5p/CXCL12 axis

Comprehending the biology of tumorigenesis needs identification of determinants of the immune reaction during cancer development. This study intends to illustrate the mechanistic actions of a bioinformatically predicted circRNA circ_002172 in cytotoxic T lymphocytes (CTL) infiltration and escape of breast cancer (BC) from immunological destruction. Expression patterns of circ_002172, miR-296-5p, and CXCL12 were determined in BC tissues and cells. Effects of circ_002172, miR-296-5p, and CXCL12 on cell viability, migration, and invasion were examined through artificial modulation of their expression. The role of circ_002172 and CXCL12 on tumorigenesis was validated in subcutaneously transplanted and orthotopically transplanted tumors in nude mice. Upregulation of circ_002172 and CXCL12 and downregulation of miR-296-5p occurred in BC tissues and cells. Circ_002172 promoted the oncogenic phenotypes of BC cells in vitro and growth of tumors in vivo, which was reversed by knockdown of CXCL12 expression. Circ_002172, as a miR-296-5p sponge, upregulated expression CXCL12. Moreover, Ectopic expression of circ_002172 inhibited cytotoxic T lymphocytes (CTL) infiltration to promote the immune escape of BC. In conclusion, the tumor-promoting role of circ_002172 in BC was achieved by inducing immune escape via the miR-296-5p/CXCL12 axis.

DHI Increases the Proliferation and Migration of Schwann Cells Through the PI3K/AKT Pathway and the Expression of CXCL12 and GDNF to Promote Facial Nerve Function Repair

The facial nerve is one of the vulnerable nerves in otolaryngology. Repair and recovery of facial nerve injury have a high priority in clinical practice. The proliferation and migration of Schwann cells are considered of great significance in the process of nerve injury repair. Danhong injection (DHI), as a common drug for cardiovascular and cerebrovascular diseases, has been fully certified in neuroprotection research, but its role in facial nerve injury is still not clear. Our study found that DHI can promote the proliferation and migration of RSC96 cells, a Schwann cell line, and this effect is related to the activation of the PI3K/AKT pathway. LY294002, an inhibitor of PI3K, inhibits the proliferation and migration of RSC96 cells. Further studies have found that DHI can also promote the expression of CXCL12 and GDNF at gene and protein levels, and CXCL12 is, while GDNF is not, PI3K/AKT pathway-dependent. Animal experiments also confirmed that DHI could promote CXCL12 and GDNF expression and promote facial nerve function recovery and myelin regeneration. In conclusion, our in vitro and in vivo experiments demonstrated that DHI could promote the proliferation and migration of Schwann cells through the PI3K/AKT pathway and increase the expression of CXCL12 and GDNF to promote facial nerve function repair.

Carcinomas assemble a filamentous CXCL12-keratin-19 coating that suppresses T cell-mediated immune attack

Cancer immunotherapy frequently fails because most carcinomas have few T cells, suggesting that cancers can suppress T cell infiltration. Here, we show that cancer cells of human pancreatic ductal adenocarcinoma (PDA), colorectal cancer, and breast cancer are coated with transglutaminase-2 (TGM2)-dependent covalent CXCL12-keratin-19 (KRT19) heterodimers that are organized as filamentous networks. Since a dimeric form of CXCL12 suppresses the motility of human T cells, we determined whether this polymeric CXCL12-KRT19 coating mediated T cell exclusion. Mouse tumors containing control PDA cells exhibited the CXCL12-KRT19 coating, excluded T cells, and did not respond to treatment with anti-PD-1 antibody. Tumors containing PDA cells not expressing either KRT19 or TGM2 lacked the CXCL12-KRT19 coating, were infiltrated with activated CD8+ T cells, and growth was suppressed with anti-PD-1 antibody treatment. Thus, carcinomas assemble a CXCL12-KRT19 coating to evade cancer immune attack.

CXCR4 Mediates Enhanced Cell Migration in CALM-AF10 Leukemia

Leukemia transformed by the CALM-AF10 chromosomal translocation is characterized by a high incidence of extramedullary disease, central nervous system (CNS) relapse, and a poor prognosis. Invasion of the extramedullary compartment and CNS requires leukemia cell migration out of the marrow and adherence to the cells of the local tissue. Cell adhesion and migration are increasingly recognized as contributors to leukemia development and therapeutic response. These processes are mediated by a variety of cytokines, chemokines, and their receptors, forming networks of both secreted and cell surface factors. The cytokines and cytokine receptors that play key roles in CALM-AF10 driven leukemia are unknown. We find high cell surface expression of the cytokine receptor CXCR4 on leukemia cells expressing the CALM-AF10 oncogenic protein, contributing to the migratory nature of this leukemia. Our discovery of altered cytokine receptor expression and function provides valuable insight into the propagation and persistence of CALM-AF10 driven leukemia.

Elevated CXCL12 in the plasma membrane of locally advanced rectal cancer after neoadjuvant chemoradiotherapy: a potential prognostic marker

Background: Neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC) has been shown to improve sphincter preservation and local pelvic control, but the efficacy of nCRT plateaus due to metastasis. CXC chemokine ligand 12 (CXCL12) has a critical impact on cancer development and metastasis.

Methods: By investigating public databases containing LARC patient data, CXCL12, CXCR4 and FAPα expression was analyzed via the Tumor Immune Estimation Resource (TIMER) and GSEA. Immunohistochemistry was applied to a total of 121 surgically resected specimens consisting of 61 LARCs after nCRT and 60 LARCs with no nCRT and 16 cases with endoscopic resection of high-grade colorectal adenoma.

Results: By investigating public databases containing LARC patient data, CXCL12 expression is correlated with poor prognosis, immune cell infiltration, epithelial- mesenchymal transition, and angiogenesis in LARC. Furthermore, radiation selectively induced CXCL12, CXCR4 and FAPα expression in tumor tissues. Immunohistochemistry results showed that the levels of CXCL12, CXCR4, and FAPα in LARC cells after nCRT were higher than in LARC cells untreated with nCRT (p < 0.001 for each). Elevated levels of CXCL12 in the plasma membrane of LARC cells after nCRT demonstrated an association with the period of freedom from recurrence (FFR) in univariate and multivariate survival analyses (p = 0.005 and p = 0.031, respectively).

Conclusions: The expression of CXCL12 may influence the survival and invasive properties of LARC cells during nCRT and promote cancer recurrence. We suggest that CXCL12 expression in the plasma membrane of radioresistant LARC cells may be a predictive factor of recurrence and a viable therapeutic strategy to control radioresistant LARC recurrence.