CXCL4 and CXCL4L1 in cancer

Hyperactivation of β-catenin signal in hepatocellular carcinoma recruits myeloid-derived suppressor cells through PF4-CXCR3 axis

The high mutation rate of CTNNB1 (37 %) and Wnt-β-catenin signal-associated genes (54 %) has been notified in hepatocellular carcinoma (HCC). The activation of Wnt-β-catenin signal pathway was reported to be associated with an immune "desert" phenotype, but the underlying mechanism remains unclear. Here we mainly employed orthotopic HCC models to explore on it. Mass cytometry depicted the immune contexture of orthotopic HCC syngeneic grafts, unveiling that the exogenous expression of β-catenin significantly increased the percentage of myeloid-derived suppressor cells (MDSCs) and decreased the percentage of CD8+ T-cells. Flow cytometry and immunohistochemistry further confirmed the findings. The protein microarray analysis, Western blot and PCR identified PF4 as its downstream regulating cytokine. Intratumorally injection of cytokine PF4 enhanced the accumulation of MDSCs. Knockout of PF4 abolished the effect of β-catenin on recruiting MDSCs. Chromatin immunoprecipitation and luciferase reporter assay demonstrated that β-catenin increases the mRNA level of PF4 via binding to PF4's promoter region. In vitro chemotaxis assay and in vivo administration of specific inhibitors identified CXCR3 on MDSCs as receptor for recruiting PF4. Lastly, the significant correlations across β-catenin, PF4 and MDSCs and CD8+ T-cells infiltration were verified in HCC clinical samples. Our results unveiled HCC tumor cell intrinsic hyperactivation of β-catenin can recruit MDSC through PF4-CXCR3, which contributes to the formation of immune "desert" phenotype. Our study provided new insights into the development of immunotherapeutic strategy of HCC with CTNNB1 mutation. SIGNIFICANCE: This study identifies PF4-CXCR3-MDSCs as a downstream mechanism underlying CTNNB1 mutation associated immune "desert" phenotype.

Platelet factor 4(PF4) and its multiple roles in diseases

Platelet factor 4 (PF4) combines with heparin to form an antigen that could produce IgG antibodies and participate in heparin-induced thrombocytopenia (HIT). PF4 has attracted wide attention due to its role in novel coronavirus vaccine-19 (COVID-9)-induced immune thrombotic thrombocytopenia (VITT) and cognitive impairments. The electrostatic interaction between PF4 and negatively charged molecules is vital in the progression of VITT, which is similar to HIT. Emerging evidence suggests its multiple roles in hematopoietic and angiogenic inhibition, platelet coagulation interference, host inflammatory response promotion, vascular inhibition, and antitumor properties. The emerging pharmacological effects of PF4 may help deepen the exploration of its mechanism, thus accelerating the development of targeted therapies. However, due to its pleiotropic properties, the development of drugs targeting PF4 is at an early stage and faces many challenges. Herein, we discussed the characteristics and biological functions of PF4, summarized PF4-mediated signaling pathways, and discussed its multiple roles in diseases to inform novel approaches for successful clinical translational research.

Research progress of CXCR3 inhibitors

The human CXCR3 receptor was initially identified and cloned in the mid-1990s. In the process of understanding CXCR3, it gradually found that it plays an important role in the process of a variety of diseases, including inflammation, immune diseases, cancer, cardiovascular diseases, central nervous system diseases, etc., which attracted the attention of many researchers. Subsequently, some small molecule inhibitors targeting CXCR3 receptors were also developed. Unfortunately, no CXCR3 inhibitors have been approved for marketing by FDA. Up to now, only one CXCR3 small molecule inhibitor has entered the clinical trial stage, but it has not achieved ideal results in the end. Therefore, there is still much to think about and explore for the development of CXCR3 inhibitors. This article reviews the important role of CXCR3 in various physiological and pathological processes and some small molecule inhibitors of CXCR3.

Meningeal macrophages inhibit chemokine signaling in pre-tumor cells to suppress mouse medulloblastoma initiation

The microenvironment profoundly influences tumor initiation across numerous tissues but remains understudied in brain tumors. In the cerebellum, canonical Wnt signaling controlled by Norrin/Frizzled4 (Fzd4) activation in meningeal endothelial cells is a potent inhibitor of preneoplasia and tumor progression in mouse models of Sonic hedgehog medulloblastoma (Shh-MB). Single-cell transcriptome profiling and phenotyping of the meninges indicate that Norrin/Frizzled4 sustains the activation of meningeal macrophages (mMΦs), characterized by Lyve1 and CXCL4 expression, during the critical preneoplastic period. Depleting mMΦs during this period enhances preneoplasia and tumorigenesis, phenocopying the effects of Norrin loss. The anti-tumorigenic function of mMΦs is derived from the expression of CXCL4, which counters CXCL12/CXCR4 signaling in pre-tumor cells, thereby inhibiting cell-cycle progression and promoting migration away from the pre-tumor niche. These findings identify a pivotal role for mMΦs as key mediators in chemokine-regulated anti-cancer crosstalk between the stroma and pre-tumor cells in the control of MB initiation.

NCOA5 Haploinsufficiency in Myeloid-Lineage Cells Sufficiently Causes Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma

BACKGROUND & AIMS

The nuclear receptor coactivator 5 (NCOA5) is a putative type 2 diabetes susceptibility gene. NCOA5 haploinsufficiency results in the spontaneous development of nonalcoholic fatty liver disease (NAFLD), insulin resistance, and hepatocellular carcinoma (HCC) in male mice; however, the cell-specific effect of NCOA5 haploinsufficiency in various types of cells, including macrophages, on the development of NAFLD and HCC remains unknown.

METHODS

Control and myeloid-lineage-specific Ncoa5 deletion (Ncoa5ΔM/+) mice fed a normal diet were examined for the development of NAFLD, nonalcoholic steatohepatitis (NASH), and HCC. Altered genes and signaling pathways in the intrahepatic macrophages of Ncoa5ΔM/+ male mice were analyzed and compared with those of obese human individuals. The role of platelet factor 4 (PF4) in macrophages and the underlying mechanism by which PF4 affects NAFLD/NASH were explored in vitro and in vivo. PF4 expression in HCC patient specimens and prognosis was examined.

RESULTS

Myeloid-lineage-specific Ncoa5 deletion sufficiently causes spontaneous NASH and HCC development in male mice fed a normal diet. PF4 overexpression in Ncoa5ΔM/+ intrahepatic macrophages is identified as a potent mediator to trigger lipid accumulation in hepatocytes by inducing lipogenesis-promoting gene expression. The transcriptome of intrahepatic macrophages from Ncoa5ΔM/+ male mice resembles that of obese human individuals. High PF4 expression correlated with poor prognosis of HCC patients and increased infiltrations of M2 macrophages, regulatory T cells, and myeloid-derived suppressor cells in HCCs.

CONCLUSIONS

Our findings reveal a novel mechanism for the onset of NAFLD/NASH and HCC initiated by NCOA5-deficient macrophages, suggesting the NCOA5-PF4 axis in macrophages as a potential target for developing preventive and therapeutic interventions against NAFLD/NASH and HCC.

New genetic and epigenetic insights into the chemokine system: the latest discoveries aiding progression toward precision medicine

Over the past thirty years, the importance of chemokines and their seven-transmembrane G protein-coupled receptors (GPCRs) has been increasingly recognized. Chemokine interactions with receptors trigger signaling pathway activity to form a network fundamental to diverse immune processes, including host homeostasis and responses to disease. Genetic and nongenetic regulation of both the expression and structure of chemokines and receptors conveys chemokine functional heterogeneity. Imbalances and defects in the system contribute to the pathogenesis of a variety of diseases, including cancer, immune and inflammatory diseases, and metabolic and neurological disorders, which render the system a focus of studies aiming to discover therapies and important biomarkers. The integrated view of chemokine biology underpinning divergence and plasticity has provided insights into immune dysfunction in disease states, including, among others, coronavirus disease 2019 (COVID-19). In this review, by reporting the latest advances in chemokine biology and results from analyses of a plethora of sequencing-based datasets, we outline recent advances in the understanding of the genetic variations and nongenetic heterogeneity of chemokines and receptors and provide an updated view of their contribution to the pathophysiological network, focusing on chemokine-mediated inflammation and cancer. Clarification of the molecular basis of dynamic chemokine-receptor interactions will help advance the understanding of chemokine biology to achieve precision medicine application in the clinic.

P-Hydroxylcinnamaldehyde induces tumor-associated macrophage polarization toward the M1 type by regulating the proteome and inhibits ESCC in vivo and in vitro

P-Hydroxylcinnamaldehyde (CMSP) was firstly isolated from Chinese medicine Cochinchinnamomordica seed (CMS) by our team and has been verified to have growth-inhibiting abilities in malignant tumors including esophageal squamous cell carcinoma (ESCC). However, the detailed mechanism of its function is still unclear. Tumor-associated macrophages (TAMs) are an essential component of the tumor microenvironment (TME), playing important roles in tumor growth, metastasis, angiogenesis, and epithelial-mesenchymal transition (EMT). In the present study, we found that the percentage of M1-like macrophages was significantly increased in TME of ESCC cell derivedxenograft tumor model after CMSP treatment, while the ratios of other immune cells showed relatively low variation. To confirm these results, we further examined the effect of CMSP on macrophage polarization in vitro. The results revealed that CMSP also could induce phorbol-12-myristate-13-acetate (PMA)-induced M0 macrophages from THP-1 and mouse peritoneal macrophages toward the M1-like macrophages. Furthermore, CMSP could exert anti-tumor effect through TAMs in vitro co-culture model, in addition, the growth inhibition effect of CMSP was partly abolished in macrophage depletion model. To determine the potential pathway of CMSP induced polarization, we used quantitative proteomics (label-free) technology to explore the proteomic changes under CMSP treatment. The results revealed that immune-activating protein and M1 macrophage biomarkers were significantly increased after CMSP treatment. More importantly, CMSP stimulated pathways related to M1 macrophage polarization, such as the NF-κB signaling pathway and Toll-like receptor pathway, indicating that CMSP might induce M1-type macrophage polarization through these pathways. In conclusion, CMSP can regulate immune microenvironment in vivo and induce TAM polarization toward the M1 type by promoting proteomic changes, and exert anti-tumor effect through TAMs.

Targeting CXCL9/10/11-CXCR3 axis: an important component of tumor-promoting and antitumor immunity

Chemokines are chemotactic-competent molecules composed of a family of small cytokines, playing a key role in regulating tumor progression. The roles of chemokines in antitumor immune responses are of great interest. CXCL9, CXCL10, and CXCL11 are important members of chemokines. It has been widely investigated that these three chemokines can bind to their common receptor CXCR3 and regulate the differentiation, migration, and tumor infiltration of immune cells, directly or indirectly affecting tumor growth and metastasis. Here, we summarize the mechanism of how the CXCL9/10/11-CXCR3 axis affects the tumor microenvironment, and list the latest researches to find out how this axis predicts the prognosis of different cancers. In addition, immunotherapy improves the survival of tumor patients, but some patients show drug resistance. Studies have found that the regulation of CXCL9/10/11-CXCR3 on the tumor microenvironment is involved in the process of changing immunotherapy resistance. Here we also describe new approaches to restoring sensitivity to immune checkpoint inhibitors through the CXCL9/10/11-CXCR3 axis.

SPI1-related protein inhibits cervical cancer cell progression and prevents macrophage cell migration

AIM

The functions and molecular mechanisms of SPI1-related protein (SPIB) were examined in cervical cancer (CC) cells.

METHODS

Genes related to miscarriage and prognosis in CC were identified by Kaplan-Meier and differential expression analysis, respectively. Cell proliferation, apoptosis, migration, and invasion were examined by cell counting kit-8, flow cytometry, transwell migration, and transwell invasion assays, respectively. The potential functions and molecular mechanisms of SPIB in CC were speculated by gene set enrichment analysis (GSEA) analysis. The mRNA and protein levels of genes were examined by RT-qPCR and western blot assays, respectively. The effect of SPIB on macrophage cells was tested by macrophage recruitment assay and bioinformatics analysis.

RESULTS

A total of 753 dysregulated genes were identified in 88 TCGA CC samples with a history of one or more miscarriages versus 208 CC samples with no miscarriage history. Also, 91 genes related to CC prognosis were identified. SPIB, a gene related to both miscarriage and CC prognosis, inhibited Hela cell proliferation, migration, and invasion, and facilitated Hela cell apoptosis. GSEA analysis disclosed that SPIB might play vital roles in immunity, chemokine signaling pathway, and macrophage chemotaxis/activation in CC. Moreover, SPIB inhibited C-X-C motif chemokine ligand 8 (CXCL8), C-C motif chemokine ligand 17 (CCL17), and C-C motif chemokine ligand 25 (CCL25) expression in Hela cells, and SPIB overexpression in Hela cells hampered THP-1 cell migration. Higher SPIB expression was associated with less M2 macrophage infiltration in CC.

CONCLUSIONS

SPIB inhibited CC-cell progression and hindered macrophage cell migration in CC.

CXCL4L1 May Help Differentiate Benign from Malignant Pulmonary Lesions and Predicts Prognosis of Patients with Lung Cancer

Background

Lung cancer (LC) is the leading type of cancer worldwide, yet it’s challenging to detect early LC. Therefore, it is valuable to explore diagnostic biomarker that can distinguish malignant pulmonary lesions from benign diseases. The potential role of plate factor-4 variant (CXCL4L1) will be investigated in detecting early LC.

Methods

A consecutive of 174 patients with single pulmonary nodule and 50 healthy controls were enrolled. Serum CXCL4L1 expression level was evaluated using ELISA. Survival curves were generated to analyze survival outcomes. Receiver operating characteristic curves were used to calculate diagnostic accuracy.

Results

Serum CXCL4L1 was downregulated in patients with LC when compared with those with lung benign lesions (LBL) or healthy controls. Meanwhile, lower serum CXCL4L1 expression was associated with advanced TNM stage and lymph node metastasis. Furthermore, a low expression of CXCL4L1 resulted in worse survival outcomes in LC patients. Serum CXCL4L1 expression obtained an area under curve (AUC) of 0.81 (95% CI: 0.74–0.88), a sensitivity of 70.6%, and a specificity of 85.8% for discriminating patients with LC form patients with LBL. In addition, serum CXCL4L1 expression achieved an AUC of 0.82 (95% CI, 0.74–0.90), a sensitivity of 72.0%, and a specificity of 85.9% for distinguishing patients with LC form healthy controls.

Conclusion

This study suggests that CXCL4L1 may prove to be a potential non-invasive diagnostic and prognostic biomarker for early LC patients.

Circular RNA hsa_circ_0069117 suppresses proliferation and migration of osteosarcoma cells lines via miR-875-3p/PF4V1 axis

Background

Osteosarcoma (OS) is one of the most common malignant bone tumors in children and adolescents. Circular RNAs (circRNAs) are critical regulators involved in multiple physiological and pathological processes. However, the underlying regulatory mechanisms of circRNA in OS are still not fully understood.

Methods

The circRNA expression profiles were downloaded from the Gene Expression Omnibus (GEO) database and analyzed by GEO2R. Bioinformatics analysis was performed to predict the potential target miRNAs of hsa_circ_0069117 and its downstream mRNAs. The co-expression of hsa_circ_0069117/miR-875-3p/PF4V1 axis was further validated in OS tissue samples via quantitative real-time PCR (qRT-PCR). Luciferase reporter gene plasmids containing the sequence of PF4V1 and hsa_circ_0069117 were constructed to verify the putative sites of miR-875-3p. Gain/loss-of-function assays were performed to verify the effect of hsa_circ_0069117 on miR-875-3p/PF4V1 expression and related pathways via qRT-PCR and Western blot. Cell counting kit-8 (CCK-8) and wound-healing assays were performed to evaluate the effect of hsa_circ_0069117 on cell proliferation and migration of MG63 and U2OS, respectively.

Results

We identified hsa_circ_0069117 as the most markedly dysregulated circRNA in OS cell lines. Bioinformatics analysis indicated that hsa_circ_0069117 might inhibit the expression of miR-875-3p, thereby promoting the expression of platelet factor 4 variant 1 (PF4V1). The expression of miR-875-3p was negatively correlated to hsa_circ_0069117 and PF4V1 in clinical samples. Luciferase reporter gene assays confirmed the binding sites of miR-875-3p on hsa_circ_0069117 and PF4V1. Gain/loss-of-function and rescue assays further indicated that hsa_circ_0069117 could significantly promote the expression of PF4V1 by sponging miR-875-3p, thereby inhibiting the proliferation and migration of OS cells by suppressing ERK1 and AKT.

Conclusion

Our study revealed that hsa_circ_0069117 is an anti-OS molecule that could substantially attenuate cell proliferation and migration of OS, which may provide a novel and reliable molecular target for the treatment of OS patients.

Contribution to the peripheral vasculopathy and endothelial cell dysfunction by CXCL4 in Systemic Sclerosis

BACKGROUND

CXCL4, a chemokine with anti-angiogenic property, is involved in systemic sclerosis (SSc) related pulmonary arterial hypertension (PAH).

OBJECTIVE

To investigated the contribution of CXCL4 to SSc development by focusing on the correlation of circulatory CXCL4 levels with their peripheral vasculopathy, and the effect of CXCL4 on endothelial cell dysfunction and the potential signaling.

METHODS

We measured the plasma CXCL4 levels in 58 patients with SSc, 10 patients with the very early diagnosis of SSc (VEDOSS), and 80 healthy controls (HCs). Then, CXCL4 concentrations were correlated with clinical features, especially the peripheral vasculopathy. These observations were further validated in an additional cohort. Moreover, we studied the anti-angiogenic effects of CXCL4 and the underlying downstream signaling in human umbilical vein endothelial cells (HUVECs) in vitro.

RESULTS

Circulating CXCL4 levels were 103.62 % higher in patients with SSc and 201.51 % higher in patients with VEDOSS than matched HCs, which were confirmed in two independent cohorts. CXCL4 levels were associated with digital ulcers (DU) and nailfold videocapillaroscopy (NVC) abnormalities in SSc. The proliferation, migration, and tube formation of HUVECs were inhibited by CXCL4 or SSc derived plasma, which reversed by CXCL4 neutralizing antibody, but failed by CXCR3 inhibitor. CXCL4 downregulated the transcription factor Friend leukaemia integration factor-1 (Fli-1) via c-Abl signaling. Furthermore, CXCL4 blocked the transforming growth factor (TGF) -β or platelet-derived growth factor (PDGF) induced cell proliferation of HUVECs.

CONCLUSIONS

CXCL4 may contribute to peripheral vasculopathy in SSc by downregulating Fli-1 via c-Abl signaling in endothelial cells and interfering angiogenesis.

Exploration of potential therapeutic and prognostic value of CXC chemokines in cervical squamous cell carcinoma and endocervical adenocarcinoma based on bioinformatics analysis

Cervical cancer, as the second most common female malignancy, brings a great health burden to women worldwide. Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) are the most common histological subtypes of cervical cancer. CXC chemokines (CXCLs) within the tumor microenvironment can modulate carcinogenesis and progression. The present study aimed to explore the therapeutic and prognostic value of different CXCLs in CESC. ONCOMINE, GEPIA, cBioPortal, TRRUST, GeneMANIA, STRING and TIMER were utilized to explore the expression, mutation and function of CXCLs in CESC, as well as their correlation with pathological and survival features of CESC patients. We found that the mRNA expression levels of CXCL1/8/9/10/11/13/16/17 in CESC were upregulated compared with normal cervical tissues, whereas CXCL12 was downregulated. No significant correlation was found between the expression levels and pathological stage of CESC patients. CESC patients with high expression of CXCL1/2/3/4/5/8 were significantly associated with poor overall survival, additionally, low mRNA level of CXCL3 was associated with better disease-free survival. Besides, a high mutation rate (43%) of CXCLs in CESC was observed. Depicted by co-expression analysis, the expression of CXCL1/2/3/6/8 showed a modest to strong correlation, while that of CXCL9/10/11/13 showed a very strong correlation. Differentially expressed CXCLs primarily functioned in chemokine signaling pathway and inflammation response, such as cell chemotaxis, chemokine activity and chemokine receptor binding. We also found the association of CXCLs with the tumor-infiltration of six types of immune cells (B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils and dendritic cells) in CESC patients. The present study elucidated that CXCLs may have the potential to be novel therapeutic targets and prognosis predictors of CESC patients.

Association of mammographic density with blood DNA methylation

Background: Altered DNA methylation may be an intermediate phenotype between breast cancer risk factors and disease. Mammographic density is a strong risk factor for breast cancer. However, no studies to date have identified an epigenetic signature of mammographic density. We performed an epigenome-wide association study of mammographic density.

Methods: White blood cell DNA methylation was measured for 385 postmenopausal women using the Illumina Infinium MethylationEPIC BeadChip array. Differential methylation was assessed using genome-wide, probe-level, and regional analyses. We implemented a resampling-based approach to improve the stability of our findings.

Results: On average, women with elevated mammographic density exhibited DNA hypermethylation within CpG islands and gene promoters compared to women with lower mammographic density. We identified 250 CpG sites for which DNA methylation was significantly associated with mammographic density. The top sites were located within genes associated with cancer, including HDLBP, TGFB2, CCT4, and PAX8, and were more likely to be located in regulatory regions of the genome. We also identified differential DNA methylation in 37 regions, including within the promoters of PAX8 and PF4, a gene involved in the regulation of angiogenesis. Overall, our results paint a picture of epigenetic dysregulation associated with mammographic density.

Conclusion: Mammographic density is associated with differential DNA methylation throughout the genome, including within genes associated with cancer. Our results suggest the potential involvement of several genes in the biological mechanisms behind differences in breast density between women. Further studies are warranted to explore these potential mechanisms and potential links to breast cancer risk.

Clinical Assay for the Early Detection of Colorectal Cancer Using Mass Spectrometric Wheat Germ Agglutinin Multiple Reaction Monitoring

Simple Summary

Colorectal cancer (CRC) is currently the third leading cause of cancer death worldwide. Early diagnosis of CRC is important for increasing the opportunity for treatment and receiving a good prognosis. The aim of our study was to develop a detection method that combined wheat germ agglutinin (WGA) chromatography with mass spectrometry (MS) for early detection of CRC. Further, machine learning algorithms and logistic regression were applied to combine multiple biomarkers we discovered. We validated in a population of 286 plasma samples the diagnostic performance of peptides corresponding to WGA-captured protein and its combination, which received a sensitivity of 84.5% and a specificity of 97.5% in the diagnoses of CRC. Proteomic biomarkers combined with algorithms can provide a powerful tool for discriminating patients with CRC and health controls (HCs). Measurements of WGA-captured PF4, ITIH4, and APOE with MS are then useful for early detection of CRC. Additionally, our study revealed the potential of applying lectin chromatography with MS for disease diagnosis.

Abstract

Colorectal cancer (CRC) is currently the third leading cause of cancer-related mortality in the world. U.S. Food and Drug Administration-approved circulating tumor markers, including carcinoembryonic antigen, carbohydrate antigen (CA) 19-9 and CA125 were used as prognostic biomarkers of CRC that attributed to low sensitivity in diagnosis of CRC. Therefore, our purpose is to develop a novel strategy for novel clinical biomarkers for early CRC diagnosis. We used mass spectrometry (MS) methods such as nanoLC-MS/MS, targeted LC-MS/MS, and stable isotope-labeled multiple reaction monitoring (MRM) MS coupled to test machine learning algorithms and logistic regression to analyze plasma samples from patients with early-stage CRC, late-stage CRC, and healthy controls (HCs). On the basis of our methods, 356 peptides were identified, 6 differential expressed peptides were verified, and finally three peptides corresponding wheat germ agglutinin (WGA)-captured proteins were semi-quantitated in 286 plasma samples (80 HCs and 206 CRCs). The novel peptide biomarkers combination of PF4^54–62, ITIH4^429–438, and APOE^198–207 achieved sensitivity 84.5%, specificity 97.5% and an AUC of 0.96 in CRC diagnosis. In conclusion, our study demonstrated that WGA-captured plasma PF4^54–62, ITIH4^429–438, and APOE^198–207 levels in combination may serve as highly effective early diagnostic biomarkers for patients with CRC.

Galectin-1 and platelet factor 4 (CXCL4) induce complementary platelet responses in vitro

Galectin-1 (gal-1) is a carbohydrate-binding lectin with important functions in angiogenesis, immune response, hemostasis and inflammation. Comparable functions are exerted by platelet factor 4 (CXCL4), a chemokine stored in the α-granules of platelets. Previously, gal-1 was found to activate platelets through integrin αIIbβ3. Both gal-1 and CXCL4 have high affinities for polysaccharides, and thus may mutually influence their functions. The aim of this study was to investigate a possible synergism of gal-1 and CXCL4 in platelet activation. Platelets were treated with increasing concentrations of gal-1, CXCL4 or both, and aggregation, integrin activation, P-selectin and phosphatidyl serine (PS) exposure were determined by light transmission aggregometry and by flow cytometry. To investigate the influence of cell surface sialic acid, platelets were treated with neuraminidase prior to stimulation. Gal-1 and CXCL4 were found to colocalize on the platelet surface. Stimulation with gal-1 led to integrin αIIbβ3 activation and to robust platelet aggregation, while CXCL4 weakly triggered aggregation and primarily induced P-selectin expression. Co-incubation of gal-1 and CXCL4 potentiated platelet aggregation compared with gal-1 alone. Whereas neither gal-1 and CXCL4 induced PS-exposure on platelets, prior removal of surface sialic acid strongly potentiated PS exposure. In addition, neuraminidase treatment increased the binding of gal-1 to platelets and lowered the activation threshold for gal-1. However, CXCL4 did not affect binding of gal-1 to platelets. Taken together, stimulation of platelets with gal-1 and CXCL4 led to distinct and complementary activation profiles, with additive rather than synergistic effects.

Mechanisms of Immunosuppression in Colorectal Cancer

Simple Summary

More emerging studies are exploring immunotherapy for solid cancers, including colorectal cancer. Besides, checkpoint blockade immunotherapy and chimeric antigen receptor (CAR) -based immune cell therapy have being examined in clinical trials for colorectal cancer patients. However, immunosuppression that leads to the blockage of normal immunosurveillance often leads to cancer development and relapse. In this study, we systematically reviewed the mechanism of immunosuppression, specifically in colorectal cancer, from different perspectives, including the natural or induced immunosuppressive cells, cell surface protein, cytokines/chemokines, transcriptional factors, metabolic alteration, phosphatase, and tissue hypoxia in the tumor microenvironment. We also discussed the progress of immunotherapies in clinical trials/studies for colorectal cancer and highlighted how different strategies for cancer therapy targeted the immunosuppression reviewed above. Our review provides some timely implications for restoring immunosurveillance to improve treatment efficacy in colorectal cancer (CRC).

Abstract

CRC is the third most diagnosed cancer in the US with the second-highest mortality rate. A multi-modality approach with surgery/chemotherapy is used in patients with early stages of colon cancer. Radiation therapy is added to the armamentarium in patients with locally advanced rectal cancer. While some patients with metastatic CRC are cured, the majority remain incurable and receive palliative chemotherapy as the standard of care. Recently, immune checkpoint blockade has emerged as a promising treatment for many solid tumors, including CRC with microsatellite instability. However, it has not been effective for microsatellite stable CRC. Here, main mechanisms of immunosuppression in CRC will be discussed, aiming to provide some insights for restoring immunosurveillance to improve treatment efficacy in CRC.

Genome-Wide Profiling of Alternative Splicing Signature Reveals Prognostic Predictor for Esophageal Carcinoma

Background

Alternative splicing (AS) is a molecular event that drives protein diversity through the generation of multiple mRNA isoforms. Growing evidence demonstrates that dysregulation of AS is associated with tumorigenesis. However, an integrated analysis in identifying the AS biomarkers attributed to esophageal carcinoma (ESCA) is largely unexplored.

Methods

AS percent-splice-in (PSI) data were obtained from the TCGA SpliceSeq database. Univariate and multivariate Cox regression analysis was successively performed to identify the overall survival (OS)-associated AS events, followed by the construction of AS predictor through different splicing patterns. Then, a nomogram that combines the final AS predictor and clinicopathological characteristics was established. Finally, a splicing regulatory network was created according to the correlation between the AS events and the splicing factors (SF).

Results

We identified a total of 2389 AS events with the potential to be used as prognostic markers that are associated with the OS of ESCA patients. Based on splicing patterns, we then built eight AS predictors that are highly capable in distinguishing high- and low-risk patients, and in predicting ESCA prognosis. Notably, the area under curve (AUC) value for the exon skip (ES) prognostic predictor was shown to reach a score of 0.885, indicating that ES has the highest prediction strength in predicting ESCA prognosis. In addition, a nomogram that comprises the pathological stage and risk group was shown to be highly efficient in predicting the survival possibility of ESCA patients. Lastly, the splicing correlation network analysis revealed the opposite roles of splicing factors (SFs) in ESCA.

Conclusion

In this study, the AS events may provide reliable biomarkers for the prognosis of ESCA. The splicing correlation networks could provide new insights in the identification of potential regulatory mechanisms during the ESCA development.

PF4V1, an miRNA-875-3p target, suppresses cell proliferation, migration, and invasion in prostate cancer and serves as a potential prognostic biomarker

Background

PF4V1 is a novel protein in inflammation, angiogenesis, and cancer. However, the pathogenesis, underlying mechanisms, and the prognostic value of PF4V1 in prostate cancer (PCa) are still unclear.

Materials and methods

The PF4V1 expression and relation with survival were analyzed based on a large sample size in the Cancer Genome Atlas. In vitro, the overexpression of PF4V1 was conducted in DU145 and LNCaP cells. Cell Counting Kit-8, colony formation, wound healing, and Transwell^® assays were preformed to test biological functions of PF4V1 and miR-875-3p in PCa. Western blotting was used to measure downstream markers in AKT pathways and epithelial–mesenchymal transition (EMT). In vivo experiments were performed to test the therapeutic effect of PF4V1 protein to PCa via a mouse model.

Results

The expression of PF4V1 was significantly lower in 497 PCa samples than in 52 normal controls (P=0.0012). High PF4V1 expression (normalized by TP53) was associated with poor disease-free survival (DFS) and good overall survival (OS) in PCa (P<0.05). PF4V1 was underexpressed in four PCa cell lines than in normal prostate cells. Overexpression of PF4V1 could significantly suppress the proliferation, migration, and invasion of DU145 and LNCaP cells (P<0.05). Moreover, miR-875-3p targeted the 3′-untranslated region of PF4V1 and derepressed the inhibitory function of PF4V1 in PCa (P<0.05). Key proteins such as p-AKT/p-ERK/Snail/Slug/N-cadherin were downregulated, while E-cadherin was upregulated when PF4V1 was overexpressed in PCa cells. Finally, intratumoral injection of PF4V1 protein could significantly inhibit PCa growth in vivo.

Conclusion

PF4V1 can suppress the proliferation, migration, and invasion of PCa cells by regulating AKT/ERK pathways and EMT. Elevated PF4V1/TP53 expression is correlated with poorer DFS and better OS in the patients with PCa. The miR-875-3p-PF4V1 axis may be a new therapeutic target site in PCa.

Chemokine Heterocomplexes and Cancer: A Novel Chapter to Be Written in Tumor Immunity

Infiltrating immune cells are a key component of the tumor microenvironment and play central roles in dictating tumor fate, either promoting anti-tumor immune responses, or sustaining tumor growth, angiogenesis and metastasis. A distinctive microenvironment is often associated to different tumor types, with substantial differences in prognosis. The production of a variety of chemotactic factors by cancer and stromal cells orchestrates cell recruitment, local immune responses or cancer progression. In the last decades, different studies have highlighted how chemotactic cues, and in particular chemokines, can act as natural antagonists or induce synergistic effects on selective receptors by forming heterocomplexes, thus shaping migratory responses of immune cells. A variety of chemokines has been described to be able to form heterocomplexes both in vitro and in vivo under inflammatory conditions, but nowadays little is known on the presence and relevance of heterocomplexes in the tumor microenvironment. In recent years, the alarmin HMGB1, which can be massively released within the tumor microenvironment, has also been described to form a complex with the chemokine CXCL12 enhancing CXCR4-mediated signaling, thus providing an additional regulation of the activity of the chemokine system. In the present review, we will discuss the current knowledge on the synergy occurring between chemokines or inflammatory molecules, and describe the multiple functions exerted by the chemokines expressed in the tumor microenvironment, pointing our attention to the synergism as a possible modulator of tumor suppression or progression.