Regulation of CXCR4 expression in human T lymphocytes by calcium and calcineurin

ScRNA-seq revealed targeting regulator of G protein signaling 1 to mediate regulatory T cells in Hepatocellular carcinoma

BACKGROUND

Regulatory T cells (Tregs) are central to determine immune response outcomes, thus targeting Tregs for immunotherapy is a promising strategy against tumor development and metastasis.

OBJECTIVES

The objective of this study was to identify genes for targeting Tregs to improve the outcome of HCC.

METHODS

We integrated expression data from different samples to remove batch effects and further applied embedding function in Scanpy to conduct sub-clustering of CD4+ T cells in HCC for each of two independent scRNA-seq data. The activity of transcription factors (TFs) was inferred by DoRothEA. Gene expression network analysis was performed in WGCNA R package. We finally used R packages (survminer and survival) to conduct survival analysis. Multiplex immunofluorescence analysis was performed to validate the result from bioinformatic analyses.

RESULTS

We found that regulator of G protein signaling 1 (RGS1) expression was significantly elevated in Tregs compared to other CD4+ T cells in two independent public scRNA-seq datasets, and increased RGS1 predicted inferior clinical outcome of HCC patients. Multiplex immunofluorescence analysis supported that the higher expression of RGS1 in HCC Tregs in tumor tissue compared to it in adjacent tissue. Moreover, RGS1 expression in Tregs was positively correlated with the expression of marker genes of Tregs, C-X-C chemokine receptor 4 (CXCR4), and three CXCR4-dependent genes in both scRNA-seq and bulk RNA-seq data. We further identified that these three genes were selectively expressed in Tregs as compared to other CD4+ T cells. The activities of two transcription factors, recombination signal binding protein for immunoglobulin kappa J region (RBPJ) and yin yang 1 (YY1), were significantly different in HCC Tregs with RGS1 high and RGS1 low.

CONCLUSIONS

Our findings suggested that RGS1 may regulate Treg function possibly through CXCR4 signaling and RGS1 could be a potential target to improve responses for immunotherapy in HCC.

The Construction and Comprehensive Analysis of a ceRNA Immunoregulatory Network and Tissue-Infiltrating Immune Cells in Atrial Fibrillation

Background

At present, the mechanisms behind atrial fibrillation (AF) pathogenesis are still unclear. We construct a ceRNA immunoregulatory network to further understand the mechanism of AF.

Methods

Four AF mRNA datasets from the Gene Expression Omnibus (GEO) database were integrated by SVA method. AF-related immune genes (AF-IRGs) were selected via combining ImmPort database with the genes in the module most associated with AF obtained by a weighted gene coexpression network analysis (WGCNA). Then, circRNA and miRNA expressions from the GEO database were extracted and mapped with related databases. Next, an immune-related circRNA-miRNA-mRNA ceRNA network was constructed and hub genes were filtered from a protein–protein interaction (PPI) network, and the differentially expressed (DE) hub genes in AF were further screened. Additionally, immune infiltration was investigated in AF by using CIBERSORT. Subsequently, the relationships between DE hub genes and AF-related infiltrating immune cells were performed by using Pearson correlation coefficients. Ulteriorly, the immune-cells-related ceRNA subnetwork in AF was built.

Results

A total of 95 AF-IRGs were detected, and an immune-related ceRNA network in AF was constructed with 12 circRNAs, 7 miRNAs and 50 mRNAs. The immune infiltration analysis indicated that a higher level of neutrophils, as well as a lower level of T cells regulatory (Tregs) and NK cells activated in AF. Four DE hub genes (CXCL12, IL7R, TNFSF13B, CD8A) were associated with Tregs or NK cells activated immune cells (P < 0.05). Tregs or NK cells activated immune cells-related ceRNA subnetwork including 5 circRNAs (has_circ_0001190, has_circ_0006725, has_circ_0079284, has_circ_0005299, and has_circ_0002103), 4 miRNAs (has-miR-198, has-miR-623, has-miR-1246, and has-miR-339-3p) and 4 DE hub genes was eventually constructed in AF.

Conclusion

Our results provide new insights into the molecular mechanisms governing AF progression from the perspective of immune-related ceRNA network.

Hypoxia-induced lncHILAR promotes renal cancer cell invasion and metastasis via ceRNA for the miR-613/206/1-1-3p/Jagged-1/Notch/CXCR4 signaling pathway

Hypoxia has been identified as a common driving factor that contributes to tumor progression, including invasion and metastasis. However, the underlying mechanisms of enhanced invasion and metastasis under hypoxia remain unclear. A hypoxic microenvironment promoted invasion and metastasis of RCC by upregulating the expression of LOC100506178, which we named Hypoxia-Induced lncRNA Associated with Renal Cell Carcinoma (lncHILAR). Knockdown of lncHILAR inhibited cell invasion and migration while overexpression of lncHILAR conversely facilitated cell invasion and migration of RCC cells. Notably, hypoxic RCC cells secreted exosomes packaged with lncHILAR which were taken up by normoxic RCC cells and then drove normoxic cell invasion. Mechanistically, hypoxia-induced-lncHILAR elevated RCC invasion and metastasis by acting as a competing endogenous (ce)RNA for miR-613/206/1-1-3p, which led to the upregulation of Jagged-1 and C-X-C Motif Chemokine Receptor 4 (CXCR4). Activation of the of Jagged-1/Notch/CXCR4 axis induced RCC metastasis. Hypoxia-induced lncHILAR promotes RCC cell invasion and metastasis via ceRNA for the miR-613/206/1-1-3p/Jagged-1/Notch/CXCR4 axis. The novel lncHILAR may thus serve as a potential biomarker and therapeutic target in RCC.

Evaluation of the mechanisms and effects of Mg-Ag-Y alloy on the tumor growth and metastasis of the MG63 osteosarcoma cell line

Osteosarcoma is a malignant primary bone tumor, which often associates with pulmonary metastasis. The radical surgery of osteosarcoma often requires internal orthopedic implants. Therefore, implants with antitumor properties should be developed. Magnesium (Mg) and its alloys possess great potential as orthopedic materials, given their biodegradable properties, superior osteogenesis performance, and antitumor features. However, problems arise with their uncontrolled degradation rates and their unknown antitumor mechanisms. In our study, when compared with pure Mg, the rare element silver alloyed with yttrium (Ag-Y) could extremely enhance the corrosion resistance of these elements, giving the Ex-Mg-1Ag-1Y alloy better anticorrosion rates. Here, we implanted the Ex-Mg-1Ag-1Y alloy and pure Mg and Ti alloy in vivo around tumors in nude mice (BALB/c). Notably, the local tumor weight in Mg alloy and pure Mg groups were much smaller than that in Ti alloy group in 36 days after surgery (6.59 ± 0.70, 6.76 ± 0.62, and 8.54 ± 0.56 g), while the general scores of lung metastasis in Mg alloy and pure Mg groups were also lower than Ti alloy group (64.50 ± 7.64, 62.73 ± 7.84, and 87.60 ± 9.43). Therefore, the Mg and Ex-Mg-1Ag-1Y alloy, both demonstrated resisting effects against local tumor growth and pulmonary metastasis, which could be performed by changing the extracellular acidosis microenvironment, elevating the Mg concentration, suppressing C-X-C chemokine receptor type 4 (CXCR4) levels, and increasing prostacyclin (PGI₂ ) synthesis. Our work revealed that the Ex-Mg-1Ag-1Y alloy may be a promising orthopedic implant for treating osteosarcoma due to its better corrosion resistance and antitumor attributes. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2537-2548, 2019.

Novel role for NFAT3 in ERK-mediated regulation of CXCR4

The G-protein coupled chemokine (C-X-C motif) receptor CXCR4 is linked to cancer, HIV, and WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. While CXCR4 is reported to be overexpressed in multiple human cancer types and many hematological cancer cell lines, we have observed poor in vitro cell surface expression of CXCR4 in many solid tumor cell lines. We explore further the possible factors and pathways involved in regulating CXCR4 expression. Here, we showed that MEK-ERK signaling pathway and NFAT3 transcriptional factor plays a novel role in regulating CXCR4 expression. When cultured as 3D spheroids, HeyA8 ovarian tumor cells showed a dramatic increase in surface CXCR4 protein levels as well as mRNA transcripts. Furthermore, HeyA8 3D spheroids showed a decrease in phospho-ERK levels when compared to adherent cells. The treatment of adherent HeyA8 cells with an inhibitor of the MEK-ERK pathway, U0126, resulted in a significant increase in surface CXCR4 expression. Additional investigation using the PCR array assay comparing adherent to 3D spheroid showed a wide range of transcription factors being up-regulated, most notably a > 20 fold increase in NFAT3 transcription factor mRNA. Finally, chromatin immunoprecipitation (ChIP) analysis showed that direct binding of NFAT3 on the CXCR4 promoter corresponds to increased CXCR4 expression in HeyA8 ovarian cell line. Taken together, our results suggest that high phospho-ERK levels and NFAT3 expression plays a novel role in regulating CXCR4 expression.

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

PURPOSE

C-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 RESULTS

According 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.

CONCLUSIONS

Our work demonstrated that silibinin is a novel CXCR4 antagonist that may have potential therapeutic use for prevention of tumor metastasis.

The MOC31PE immunotoxin reduces cell migration and induces gene expression and cell death in ovarian cancer cells

Background

The standard treatment of ovarian cancer with chemotherapy often leads to drug resistance and relapse of the disease, and the need for development of novel therapy alternatives is obvious. The MOC31PE immunotoxin binds to the cell surface antigen EpCAM, which is expressed by the majority of epithelial cancers including ovarian carcinomas, and we studied the cytotoxic effects of MOC31PE in ovarian cancer cells.

Methods

Investigation of the effects of MOC31PE treatment on protein synthesis, cell viability, proliferation and gene expression of the ovarian cancer cell lines B76 and HOC7.

Results

MOC31PE treatment for 24 h caused a dose-dependent reduction of protein synthesis with ID₅₀ values of less than 10 ng/ml, followed by reduced cell viability. In a gene expression array monitoring the expression of 84 key genes in cancer pathways, 13 of the genes were differentially expressed by MOC31PE treatment in comparison to untreated cells. By combining MOC31PE and the immune suppressor cyclosporin A (CsA) the MOC31PE effect on protein synthesis inhibition and cell viability increased tenfold. Cell migration was also reduced, both in the individual MOC31PE and CsA treatment, but even more when combining MOC31PE and CsA. In tumor metastasis PCR arrays, 23 of 84 genes were differentially expressed comparing CsA versus MOC31PE + CsA treatment. Increased expression of the tumor suppressor KISS1 and the nuclear receptor NR4A3 was observed, and the differential candidate gene expression was confirmed in complementary qPCR analyses. For NR4A3 this was not accompanied by increased protein expression. However, a subcellular fractionation assay revealed increased mitochondrial NR4A3 in MOC31PE treated cells, suggesting a role for this protein in MOC31PE-induced apoptotic cell death.

Conclusion

The present study demonstrates that MOC31PE may become a new targeted therapy for ovarian cancer and that the MOC31PE anti-cancer effect is potentiated by CsA.

Defective CXCR4 expression in aged bone marrow cells impairs vascular regeneration

The chemokine stromal cell-derived factor-1 (SDF-1) plays a critical role in mobilizing precursor cells in the bone marrow and is essential for efficient vascular regeneration and repair. We recently reported that calcium augments the expression of chemokine receptor CXCR4 and enhances the angiogenic potential of bone marrow derived cells (BMCs). Neovascularization is impaired by aging therefore we suggested that aging may cause defects of CXCR4 expression and cellular responses to calcium. Indeed we found that both the basal and calcium-induced surface expression of CXCR4 on BMCs was significantly reduced in 25-month-old mice compared with 2-month-old mice. Reduced Ca-induced CXCR4 expression in BMC from aged mice was associated with defective calcium influx. Diminished CXCR4 surface expression in BMC from aged mice correlated with diminished neovascularization in an ischemic hindlimb model with less accumulation of CD34⁺ progenitor cells in the ischemic muscle with or without local overexpression of SDF-1. Intravenous injection of BMCs from old mice homed less efficiently to ischemic muscle and stimulated significantly less neovascularization compared with the BMCs from young mice. Transplantation of old BMCs into young mice did not reconstitute CXCR4 functions suggesting that the defects were not reversible by changing the environment. We conclude that defects of basal and calcium-regulated functions of the CXCR4/SDF-1 axis in BMCs contribute significantly to the age-related loss of vasculogenic responses.

Regulation of expression of stromal-derived factor-1 receptors: CXCR4 and CXCR7 in human rhabdomyosarcomas

Rhabdomyosarcomas (RMS) express CXCR4 and CXCR7 receptors that bind prometastatic alpha-chemokine stromal-derived factor-1 (SDF-1). In this report, we analyzed the activity of both promoters in a model of less metastatic human embryonal-RMS cell line (RD) and more metastatic alveolar-like RMS (RD cells transduced with paired box gene 3/forkhead homologue; PAX3-FKHR fusion gene). First, CXCR4 is barely detectable in RD and becomes upregulated in RD/PAX3-FKHR cells. In contrast, CXCR7 highly expressed in RD becomes downregulated in RD/PAX3-FKHR cells. Next, promoter deletion and mutation studies revealed that whereas (a) expression of CXCR4 in RD and RD/PAX3-FKHR cells required nuclear respiratory factor-1 (NRF-1) binding site and (b) was additionally upregulated by direct interaction of NRF-1 with PAX3-FKHR, CXCR7 promoter activity required a proximal nuclear factor-kappaB-binding motif. The requirement of these factors for CXCR4 and CXCR7 promoter activities was additionally supported after blocking NRF-1 and nuclear factor-kappaB. Furthermore, CXCR4 expression in PAX3-FKHR(+) RMS cells seems to be enhanced because of the interaction of PAX3-FKHR and NRF-1 proteins in the proximal part of the promoter that prevents access of the negative regulator of transcription YY1 to its binding site. Finally, although hypoxia enhances CXCR4 and CXCR7 promoter activity and receptor expression in RD cells, it inhibits CXCR7 expression in RD/PAX3-FKHR cells. In conclusion, SDF-1 binding receptors CXCR4 and CXCR7 are differently regulated in RMS cells. The upregulation of CXCR4 and downregulation of CXCR7 expression by PAX3-FKHR or hypoxia may give SDF-1 an advantage to better engage the CXCR4 receptor, thus increasing RMS motility.

IgE-FcepsilonRI interactions determine HIV coreceptor usage and susceptibility to infection during ontogeny of mast cells

Progenitor mast cells (prMCs), derived from CD34(+) precursors are CD4(+)/CCR5(+)/CXCR4(+) and susceptible to CCR5(R5)-tropic virus but only marginally susceptible to CXCR4(X4)-tropic HIV. As infected prMCs mature within extravascular compartments, they become both latently infected and HIV-infection resistant, and thus capable of establishing an inducible reservoir of CCR5-tropic infectious clones. In this report we provide the first evidence that IgE-FcepsilonRI interactions, occurring during a unique period of mast cell (MC) ontogeny, enhance prMC susceptibility to X4 and R5X4 virus. IgE-FcepsilonRI interactions significantly increased expression of CXCR4 mRNA ( approximately 400- to 1800-fold), enhanced prMC susceptibility to X4 and R5X4 virus ( approximately 3000- to 16,000-fold), but had no significant effect on CD4, CCR3, or CCR5 expression, susceptibility to R5 virus, or degranulation. Enhanced susceptibility to infection with X4 virus occurred during the first 3-5 wk of MC ontogeny and was completely inhibited by CXCR4-specific peptide antagonists and omalizumab, a drug that inhibits IgE-FcepsilonRI interactions. IgE-FcepsilonRI coaggregation mediated by HIVgp120 or Schistosoma mansoni soluble egg Ag accelerated maximal CXCR4 expression and susceptibility to X4 virus by prMCs. Our findings suggest that for HIV-positive individuals with atopic or helminthic diseases, elevated IgE levels could potentially influence the composition of CXCR4-tropic and R5X4-tropic variants archived within the long-lived tissue MC reservoir created during infection.

Extracellular calcium increases CXCR4 expression on bone marrow-derived cells and enhances pro-angiogenesis therapy

Cell surface receptors play major roles in the mobilization and homing of progenitor cells from the bone marrow to peripheral tissues. CXCR4 is an important receptor that regulates homing of leucocytes and endothelial progenitors in response to the chemokine stromal cell-derived factor-1 (SDF-1). Ionic calcium is also known to regulate chemotaxis of selective bone marrow cells (BMCs) through the calcium-sensing receptor, CaR. Here we show that calcium regulates CXCR4 expression and BMC responses to SDF-1. CaCl₂ treatment of BMC induced a time- and dose-dependent increase in both the transcription and cell surface expression of CXCR4. BMC subpopulations expressing VEGFR2⁺, CD34⁺ and cKit⁺/Sca-1⁺ were especially sensitive to calcium. The effects were blocked by calcium influx inhibitors, anti-CaR antibody and the protein synthesis inhibitor cycloheximide, but not by the CXCR4 antagonist AMD3100. Calcium treatment also enhanced SDF-1-mediated CXCR4 internalization. These changes were reflected in significantly improved chemotaxis by SDF-1, which was abolished by AMD3100 and by antibody against CXCR4. Calcium pre-treatment improved homing of CD34⁺ BMCs to ischemic muscle in vivo, and enhanced revascularization in ischemic mouse hindlimbs. Our results identify calcium as a positive regulator of CXCR4 expression that promotes stem cell mobilization, homing and therapy.

YY1 and FoxD3 regulate antiretroviral zinc finger protein OTK18 promoter activation induced by HIV-1 infection

OTK18 is a C2H2 type zinc finger protein involved in the regulation of HIV-1 replication in human mononuclear phagocytes. Previously, we reported OTK18 expression in brain perivascular macrophages but not in microglia in HIV encephalitis brain. We have cloned the OTK18 promoter region proximal to the transcriptional start site and determined the region responsible (-884/+1) for the basal transcriptional activity in a microglia cell line. Sequential deletion mutation analyses reveal three important response elements: Yingyang-1 (YY1; -805/-777), an HIV-1 response element for promoter activation; FoxD3 (-743/-725), a negative regulatory element; and Ets response element (-725/-707), a basal transcriptional activity response element. HIV-1 infection-induced upregulation of YY1 and c-Ets-1 protein, binding to the promoter region as determined by immunoblotting and chromatin immunoprecipitation and polymerase chain reaction (PCR) assays, and induction of YY1 was also observed in virus-infected monocyte-derived macrophages. Silencing of FoxD3 and YY1 in the cell line by small interfering RNA duplexes specific to these molecules significantly up- and downregulated basal OTK18 promoter activity in FoxD3 and YY1 response element-dependent manners, respectively. On the other hand, infection of primary cultured human microglia significantly reduced YY1 expression and induced FoxD3 as determined by immunoblotting and reverse transcription real-time PCR. These data suggest that HIV-1 induces OTK18 expression through a YY1-mediated manner in human macrophages, although its gene expression is suppressed by FoxD3 upregulation and YY1 downregulation in human microglia. This mechanism may explain the perivascular macrophage-specific expression of OTK18 in HIV encephalitis brains.

cAMP-induced PKCzeta activation increases functional CXCR4 expression on human CD34+ hematopoietic progenitors

Chemokines are key regulators of hematopoiesis and host defense. We report here that functional expression of the chemokine receptor CXCR4 on human immature CD34+ hematopoietic progenitors was increased as a result of sustained elevation in cellular cAMP by dbcAMP and prostaglandin E2. This effect of cAMP was specifically mediated by PKCzeta activity. CXCR4 expression and PKCzeta activation by cAMP were decreased after the inhibition of cAMP effector-Rap1 by Spa1 overexpression. Interference with the activation of Rac1, a downstream target of Rap1, prevented the cAMP-induced increase in PKCzeta activity and CXCR4 levels. Functional manifestation of the effects of cAMP-elevating agents revealed an increased ability of human CD34+ cells to transmigrate the bone marrow (BM) endothelial layer and adhere to BM stroma in vitro, and it augmented the homing potential to the BM and spleens of immunodeficient mice in a Rac1- and a PKCzeta-dependent manner. cAMP- and TNFalpha-stimulated pathways converged in PKCzeta-activated CXCR4 expression and MMP-2/MMP-9 secretion. cAMP treatment had a beneficial effect on CD34+ cell survival in a PKCzeta-mediated fashion. Taken together, our data reveal major roles for cAMP-induced PKCzeta activation in signaling governing the motility and development of CD34+ cells.

The role of γδ T cells in the regulation of neutrophil-mediated tissue damage after thermal injury

Thermal injury induces an inflammatory response that contributes to the development of secondary tissue damage. Neutrophil recruitment and activation are in part responsible for this tissue damage. Although gammadelta T cells have been shown to regulate the inflammatory responses in tissues that are prone to neutrophil-mediated injury post-burn, their role in the induction of secondary tissue injury post-burn remains unknown. To study this, gammadelta T cell-deficient (gammadelta TCR-/-) and wild-type (WT) mice were subjected to thermal injury or sham procedure, and tissue samples were isolated 1-24 h thereafter. Burn injury induced neutrophil accumulation in the lung and small intestines of WT mice at 1-3 h post-injury. No such increase in neutrophil tissue content was observed in gammadelta TCR-/- mice. An increase in tissue wet/dry weight ratios was also observed in these organs at 3 h post-burn in WT but not in gammadelta TCR-/- mice. A parallel increase in plasma and small intestine levels of the chemokines macrophage-inflammatory protein-1beta (chemokine ligand 4) and keratinocyte-derived chemokine (CXC chemokine ligand 1) were observed in injured WT mice but not in injured gammadelta TCR-/- mice. Increased activation (CD120b expression) of the circulating gammadelta T cell population was also observed at 3 h post-burn in WT mice. These results indicate the gammadelta T cells, through the production of chemokines, play a central role in the initiation of neutrophil-mediated tissue damage post-burn.