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

Progress of immunotherapies in gestational trophoblastic neoplasms

BACKGROUND

Different from other malignant gynecologic tumors, gestational trophoblastic neoplasms (GTNs) exhibit an exceptionally high cure rate primarily through chemotherapeutic interventions. However, there exists a small subset of refractory GTNs that do not respond to conventional chemotherapies. In such cases, the emergence of immunotherapies has demonstrated significant benefits in managing various challenging GTNs.

PURPOSE

This article aims to provide a comprehensive and systematic review of the immune microenvironment and immunotherapeutic approaches for GTNs. The purpose is to identify potential biomarkers that could enhance disease management and summarize the available immunotherapies for ease of reference.

METHODS

We reviewed the relevant literatures toward immunotherapies of GTNs from PubMed.

CONCLUSION

Current immunotherapeutic strategies for GTNs mainly revolve around immune checkpoint inhibitors (ICIs) targeting programmed death receptor 1 (PD-1) and programmed cell death ligand 1 (PD-L1). Prominent examples include avelumab, pembrolizumab, and camrelizumab. However, existing researches into the underlying mechanisms are still limited.

Mitochondria-derived peptide SHLP2 regulates energy homeostasis through the activation of hypothalamic neurons

Small humanin-like peptide 2 (SHLP2) is a mitochondrial-derived peptide implicated in several biological processes such as aging and oxidative stress. However, its functional role in the regulation of energy homeostasis remains unclear, and its corresponding receptor is not identified. Hereby, we demonstrate that both systemic and intracerebroventricular (ICV) administrations of SHLP2 protected the male mice from high-fat diet (HFD)-induced obesity and improved insulin sensitivity. In addition, the activation of pro-opiomelanocortin (POMC) neurons by SHLP2 in the arcuate nucleus of the hypothalamus (ARC) is involved in the suppression of food intake and the promotion of thermogenesis. Through high-throughput structural complementation screening, we discovered that SHLP2 binds to and activates chemokine receptor 7 (CXCR7). Taken together, our study not only reveals the therapeutic potential of SHLP2 in metabolic disorders but also provides important mechanistic insights into how it exerts its effects on energy homeostasis.

Regulation and Function of Chemokines at the Maternal–Fetal Interface

Successful pregnancy requires the maternal immune system to tolerate the semi-allogeneic embryo. A good trophoblast function is also essential for successful embryo implantation and subsequent placental development. Chemokines are initially described in recruiting leukocytes. There are rich chemokines and chemokine receptor system at the maternal–fetal interface. Numerous studies have reported that they not only regulate trophoblast biological behaviors but also participate in the decidual immune response. At the same time, the chemokine system builds an important communication network between fetally derived trophoblast cells and maternally derived decidual cells. However, abnormal functions of chemokines or chemokine receptors are involved in a series of pregnancy complications. As growing evidence points to the roles of chemokines in pregnancy, there is a great need to summarize the available data on this topic. This review aimed to describe the recent research progress on the regulation and function of the main chemokines in pregnancy at the maternal–fetal interface. In addition, we also discussed the potential relationship between chemokines and pregnancy complications.

Low-Molecular-Weight Heparin Enhanced Therapeutic Effects of Human Adipose-Derived Stem Cell Administration in a Mouse Model of Lupus Nephritis

Background

Lupus nephritis is a life-threatening complication in systemic lupus erythematosus (SLE), but the efficiency of current therapies involving corticosteroids, immunosuppressants, and biological agents is limited. Adipose-derived mesenchymal stem cells (ASCs) are gaining attention as a novel treatment for inflammation in SLE. Low-molecular-weight heparin (LMWH) exhibits multiple functions including anti-inflammatory, anti-fibrotic, and cell function-promoting effects. LMWH stimulation is expected to increase the therapeutic effect of ASCs by promoting cellular functions. In this study, we investigated the effects of LMWH on ASC functions and the therapeutic effect of LMWH-activated human-ASCs (hep-hASCs) in an SLE mouse model.

Methods

The cellular functions of human-derived ASCs stimulated with different LMWH concentrations were observed, and the optimum LMWH dose was selected. The mice were assigned to control, human-ASC, and hep-hASC groups; treatments were performed on week 20. Twenty-six week-old mice were sacrificed, and urine protein score, serum blood urea nitrogen, creatinine (Cr), anti-ds DNA IgG antibody, and serum IL-6 levels were analyzed in each group. Mice kidneys were evaluated via histological examination, immunohistochemical staining, and gene expression levels.

Results

LMWH significantly promoted ASC migration and proliferation and hepatocyte growth factor production and upregulated immunomodulatory factors in vitro. Hep-hASC administration resulted in significant disease activity improvement including proteinuria, serum Cr and IL-6 levels, anti-ds DNA IgG antibody, glomerulonephritis, and immune complex in mice. Inflammation and fibrosis in kidneys was significantly suppressed in the hep-hASC group; the gene expression levels of TNF-alpha, TIMP-2, and MMP-2 was significantly downregulated in the hep-hASC group compared with the control group.

Conclusions

Hep-hASC exhibited higher anti-inflammatory and anti-fibrotic effects than hASCs and may be a candidate tool for SLE treatment in future.

Emerging Roles of the Atypical Chemokine Receptor 3 (ACKR3) in Cardiovascular Diseases

Chemokines, and their receptors play a crucial role in the pathophysiology of cardiovascular diseases (CVD). Chemokines classically mediate their effects by binding to G-protein-coupled receptors. The discovery that chemokines can also bind to atypical chemokine receptors (ACKRs) and initiate alternative signaling pathways has changed the paradigm regarding chemokine-related functions. Among these ACKRs, several studies have highlighted the exclusive role of ACKR3, previously known as C-X-C chemokine receptor type 7 (CXCR7), in CVD. Indeed, ACKR3 exert atheroprotective, cardioprotective and anti-thrombotic effects through a wide range of cells including endothelial cells, platelets, inflammatory cells, fibroblasts, vascular smooth muscle cells and cardiomyocytes. ACKR3 functions as a scavenger receptor notably for the pleiotropic chemokine CXCL12, but also as a activator of different pathways such as β-arrestin-mediated signaling or modulator of CXCR4 signaling through the formation of ACKR3-CXCR4 heterodimers. Hence, a better understanding of the precise roles of ACKR3 may pave the way towards the development of novel and improved therapeutic strategies for CVD. Here, we summarize the structural determinant characteristic of ACKR3, the molecules targeting this receptor and signaling pathways modulated by ACKR3. Finally, we present and discuss recent findings regarding the role of ACKR3 in CVD.

The CXCL12-CXCR4 Signaling Axis Plays a Key Role in Cancer Metastasis and is a Potential Target for Developing Novel Therapeutics against Metastatic Cancer

Metastasis is the main cause of death in cancer patients; there is currently no effective treatment for cancer metastasis. This is primarily due to our insufficient understanding of the metastatic mechanisms in cancer. An increasing number of studies have shown that the C-X-C motif chemokine Ligand 12 (CXCL12) is overexpressed in various tissues and organs. It is a key niche factor that nurtures the pre-metastatic niches (tumorigenic soil) and recruits tumor cells (oncogenic "seeds") to these niches, thereby fostering cancer cell aggression and metastatic capabilities. However, the C-X-C motif chemokine Receptor 4 (CXCR4) is aberrantly overexpressed in various cancer stem/progenitor cells and functions as a CXCL12 receptor. CXCL12 activates CXCR4 as well as multiple downstream multiple tumorigenic signaling pathways, promoting the expression of various oncogenes. Activation of the CXCL12-CXCR4 signaling axis promotes Epithelial-Mesenchymal Transition (EMT) and mobilization of cancer stem/progenitor cells to pre-metastatic niches. It also nurtures cancer cells with high motility, invasion, and dissemination phenotypes, thereby escalating multiple proximal or distal cancer metastasis; this results in poor patient prognosis. Based on this evidence, recent studies have explored either CXCL12- or CXCR4-targeted anti-cancer therapeutics and have achieved promising results in the preclinical trials. Further exploration of this new strategy and its potent therapeutics effect against metastatic cancer through the targeting of the CXCL12- CXCR4 signaling axis may lead to a novel therapy that can clean up the tumor microenvironment ("soil") and kill the cancer cells, particularly the cancer stem/progenitor cells ("seeds"), in cancer patients. Ultimately, this approach has the potential to effectively treat metastatic cancer.

CXCL12 in normal and pathological pregnancies: A review

The survival of allogeneic fetuses during pregnancy is a rather paradoxical phenomenon with a complex mechanism. Chemokine ligand12 (CXCL12) and its receptors CXC chemokine receptor (CXCR)4 and 7 are extensively found in placenta tissues and cells, including trophoblast cells, vascular endothelial cells, and decidual stromal and decidual immune cells (eg, NK cells and regulatory T cells). Evidence has illustrated that the CXClL12/CXCR4/CXCR7 axis could enhance the cross talk at the maternal-fetal interface through multiple processes, such as invasion and placental angiogenesis, which appears to be critical signaling components in placentation and fetal outcome. In addition, an increasing number of studies have demonstrated that the CXCL12/CXCR4/CXCR7 axis also stands out for its pleiotropic roles in several pregnancy-associated diseases (eg, recurrent spontaneous abortion (RSA), pre-eclampsia (PE), and preterm labor). In the present review, the different biological properties and signaling in physiological and pathological pregnancy conditions of CXCL12/CXCR4/CXCR7 axis were discussed, with the aim of obtaining a further understanding of the regulatory mechanisms and highlighting their potential as a target for therapeutic approaches.

miR-539-5p inhibits experimental choroidal neovascularization by targeting CXCR7

Stromal cell-derived factor-1 (SDF-1) has been previously confirmed to participate in the formation of choroidal neovascularization (CNV) via its receptor, CXC chemokine receptor (CXCR) 4; CXCR7 is a recently identified receptor for SDF-1. The molecular mechanisms and therapeutic value of CXCR7 in CNV remain undefined. In this study, experimental CNV was induced by laser photocoagulation in Brown-Norway pigmented rats, and aberrant CXCR7 overexpression was detected in the retinal pigment epithelial/choroid/sclera tissues of laser-injured eyes. Blockade of CXCR7 activation via CXCR7 knockdown or neutralizing Ab administration inhibited SDF-1-induced cell survival and the tubular formation of human retinal microvascular endothelial cells (HRMECs) in vitro and reduced CNV leakage and lesion size in vivo. By using microRNA array screening and bioinformatic analyses, we identified miR-539-5p as a regulator of CXCR7. Transfection of HRMECs and choroid-retinal endothelial (RF/6A) cells with the miR-539-5p mimic inhibited their survival and tube formation, whereas CXCR7 overexpression rescued the suppressive effect of miR-539-5p. The antiangiogenic activities of the miR-539-5p mimic were additionally demonstrated in vivo by intravitreal injection. ERK1/2 and AKT signaling downstream of CXCR7 is involved in the miR-539-5p regulation of endothelial cell behaviors. These findings suggest that the manipulation of miR-539-5p/CXCR7 levels may have important therapeutic implications in CNV-associated diseases.-Feng, Y., Wang, J., Yuan, Y., Zhang, X., Shen, M., Yuan, F. miR-539-5p inhibits experimental choroidal neovascularization by targeting CXCR7.

CXCL12 enhances angiogenesis through CXCR7 activation in human umbilical vein endothelial cells

Angiogenesis is the process by which new vessels form from existing vascular networks. Human umbilical vein endothelial cells (HUVECs) may contribute to the study of vascular repair and angiogenesis. The chemokine CXCL12 regulates multiple cell functions, including angiogenesis, mainly through its receptor CXCR4. In contrast to CXCL12/CXCR4, few studies have described roles for CXCR7 in vascular biology, and the downstream mechanism of CXCR7 in angiogenesis remains unclear. The results of the present study showed that CXCL12 dose-dependently enhanced angiogenesis in chorioallantoic membranes (CAMs) and HUVECs. The specific activation of CXCR7 with TC14012 (a CXCR7 agonist) resulted in the significant induction of tube formation in HUVECs and in vivo. Further evidence suggested that CXCL12 induced directional polarization and migration in the HUVECs, which is necessary for tube formation. Moreover, CXCR7 translocalization was observed during the polarization of HUVECs in stripe assays. Finally, treatment with TC14012 also significantly increased PI3K/Akt phosphorylation, and tube formation was blocked by treating HUVECs with an Akt inhibitor. Overall, this study indicated that CXCL12-stimulated CXCR7 acts as a functional receptor to activate Akt for angiogenesis in HUVECs and that CXCR7 may be a potential target molecule for endothelial regeneration and repair after vascular injury.

Inhibitory effects of delphinidin on the proliferation of ovarian cancer cells via PI3K/AKT and ERK 1/2 MAPK signal transduction

Delphinidin is a member of the anthocyanidin family and is a natural pigment in red cabbage, berries, sweet potatoes and grapes. It possesses nutraceutical properties against various chronic diseases and types of cancer. However, little is known about its preventative effects on epithelial ovarian cancer, a disease that is associated with a low survival rate, a poor prognosis and a high rate of recurrence. The results of the present study demonstrated that the proliferation of SKOV3 cells decreased in a dose-dependent manner in response to treatment with delphinidin, and the phosphorylation of carcinogenic protein kinases associated with the progression of epithelial ovarian cancer was affected by delphinidin treatment. The levels of phosphorylated protein kinase B (AKT), ribosomal protein S6 kinase β-1 (P70S6K), ribosomal protein S (S6), extracellular signal-regulated kinase (ERK)1/2 and p38 were suppressed by increasing concentrations of delphinidin. Furthermore, the combination of certain pharmacological inhibitors, including phosphoinositide 3-kinase (PI3K; LY294002), ERK1/2 (U0126) and delphinidin significantly reduced the proliferation of SKOV3 cells and the phosphorylation of each of those target proteins. In addition, delphinidin treatment exerted anti-proliferative effects on paclitaxel-resistant SKOV3 cells, compared with treatment with paclitaxel alone. These results indicate that delphinidin inhibits the proliferation of SKOV3 cells through inactivation of PI3K/AKT and ERK1/2 mitogen-activated protein kinase signaling cascades, and that this cell signaling pathway may be a pivotal therapeutic target for the prevention of epithelial ovarian cancer, including paclitaxel-resistant ovarian cancer.

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

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

CXCR4, CXCR7, and CXCL12 are associated with trophoblastic cells apoptosis and linked to pathophysiology of severe preeclampsia

Preeclampsia is a pregnancy disorder with sudden onset of maternal hypertension and proteinuria, which is characterized by defective cytotrophoblast invasion, increased apoptosis in cytotrophoblast, and diminished syncytial differentiation. In this study, samples from 11 mild preeclamptic patients, 18 severe preeclamptic patients, and 21 normal pregnant women were collected. The expression level of CXCL12 and its two receptors (CXCR4 and CXCR7) in these samples and their relationship with apoptosis were investigated. Morphological change of trophoblast cells that was observed by scanning electron microscope (SEM) indicated a significant tendency of apoptosis in the preeclamptic placenta. Immunohistochemical staining showed that expression level of three proteins was significantly lower in severe preeclamptic placentas compared with normal placentas (P<0.05), whereas no significant difference was found between mild preeclamptic and normal placentas (P>0.05). Real time quantitative PCR (RT-qPCR) and Western blot showed that both mRNA and protein expression level of CXCR4, CXCR7, and CXCL12 of trophoblasts were lower in the severe preeclampsia group than that in the normal group (P<0.05 for mRNA, P<0.01 for protein). In conclusion, our data revealed that the roles of CXCR4, CXCR7, and CXCL12 are associated with trophoblastic cells apoptosis and may be linked to the occurrence and development of severe preeclampsia.

Insights into the mechanism of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis

The chemokine CXCL12 and its receptor CXCR4 are important signaling components required for human blastocyst implantation and the progression of pregnancy. Growing evidence indicates that the CXCL12/CXCR4 axis can regulate trophoblast function and uterine spiral artery remodeling, which plays a fundamental role in placentation and fetal outcome. The orphan receptor CXCR7 is also believed to partly regulate the function of the CXCL12/CXCR4 axis. Additionally, the CXCL12/CXCR4/CXCR7 axis can enhance the cross-talk between trophoblasts and decidual cells such as uterine natural killer cells and decidual stromal cells which are involved in regulation of trophoblast differentiation and invasion and placental angiogenesis. In addition, recent studies proved that CXCL12 expression is elevated in the placenta and mid-trimester amniotic fluid of pregnant women with preeclampsia, implying that dysregulation of CXCL12 plays a role in the pathogenesis of preeclampsia. Further understanding of the regulatory mechanisms of CXCL12-mediated signaling in trophoblast functions and placental angiogenesis may help to design novel therapeutic approaches for pregnancy-associated diseases.