Platelet Factor 4 Inhibits IL-17/Stat3 Pathway via Upregulation of SOCS3 Expression in Melanoma

Proteinase 3 depletion attenuates leukemia by promoting myeloid differentiation

Hematopoietic stem and progenitor cells (HSPCs) that have impaired differentiation can transform into leukemic blasts. However, the mechanism that controls differentiation remains elusive. Here, we show that the genetic elimination of Proteinase 3 (PRTN3) in mice led to spontaneous myeloid differentiation. Mechanistically, our findings indicate that PRTN3 interacts with the N-terminal of STAT3, serving as a negative regulator of STAT3-dependent myeloid differentiation. Specifically, PRTN3 promotes STAT3 ubiquitination and degradation, while simultaneously reducing STAT3 phosphorylation and nuclear translocation during G-CSF-stimulated myeloid differentiation. Strikingly, pharmacological inhibition of STAT3 (Stattic) partially counteracted the effects of PRTN3 deficiency on myeloid differentiation. Moreover, the deficiency of PRTN3 in primary AML blasts promotes the differentiation of those cells into functional neutrophils capable of chemotaxis and phagocytosis, ultimately resulting in improved overall survival rates for recipients. These findings indicate PRTN3 exerts an inhibitory effect on STAT3-dependent myeloid differentiation and could be a promising therapeutic target for the treatment of acute myeloid leukemia.

Role of HDAC6-STAT3 in immunomodulatory pathways in Colorectal cancer cells

Colorectal cancer (CRC) is one of the most common malignant neoplasms and the second leading cause of death from tumors worldwide. Therefore, there is a great need to study new therapeutical strategies, such as effective immunotherapies against these malignancies. Unfortunately, many CRC patients do not respond to current standard immunotherapies, making it necessary to search for adjuvant treatments. Histone deacetylase 6 (HDAC6) is involved in several processes, including immune response and tumor progression. Specifically, it has been observed that HDAC6 is required to activate the Signal Transducer and Activator of Transcription 3 (STAT3), a transcription factor involved in immunogenicity, by activating different genes in these pathways, such as PD-L1. Over-expression of immunosuppressive pathways in cancer cells deregulates T-cell activation. Therefore, we focused on the pharmacological inhibition of HDAC6 in CRC cells because of its potential as an adjuvant to avoid immunotolerance in immunotherapy. We investigated whether HDAC6 inhibitors (HDAC6is), such as Nexturastat A (NextA), affected STAT3 activation in CRC cells. First, we found that NextA is less cytotoxic than the non-selective HDACis panobinostat. Then, NextA modified STAT3 and decreased the mRNA and protein expression levels of PD-L1. Importantly, transcriptomic analysis showed that NextA treatment affected the expression of critical genes involved in immunomodulatory pathways in CRC malignancies. These results suggest that treatments with NextA reduce the functionality of STAT3 in CRC cells, impacting the expression of immunomodulatory genes involved in the inflammatory and immune responses. Therefore, targeting HDAC6 may represent an interesting adjuvant strategy in combination with immunotherapy.

A narrative review for platelets and their RNAs in cancers: New concepts and clinical perspectives

Recent years have witnessed a growing body of evidence suggesting that platelets are involved in several stages of the metastatic process via direct or indirect interactions with cancer cells, contributing to the progression of neoplastic malignancies. Cancer cells can dynamically exchange components with platelets in and out of blood vessels, and directly phagocytose platelets to hijack their proteome, transcriptome, and secretome, or be remotely regulated by metabolites or microparticles released by platelets, resulting in phenotypic, genetic, and functional modifications. Moreover, platelet interactions with stromal and immune cells in the tumor microenvironment lead to alterations in their components, including the ribonucleic acid (RNA) profile, and complicate the impact of platelets on cancers. A deeper understanding of the roles of platelets and their RNAs in cancer will contribute to the development of anticancer strategies and the optimization of clinical management. Encouragingly, advances in high-throughput sequencing, bioinformatics data analysis, and machine learning have allowed scientists to explore the potential of platelet RNAs for cancer diagnosis, prognosis, and guiding treatment. However, the clinical application of this technique remains controversial and requires larger, multicenter studies with standardized protocols. Here, we integrate the latest evidence to provide a broader insight into the role of platelets in cancer progression and management, and propose standardized recommendations for the clinical utility of platelet RNAs to facilitate translation and benefit patients.

SEC23A Inhibit Melanoma Metastatic through Secretory PF4 Cooperation with SPARC to Inhibit MAPK Signaling Pathway

Metastasis of melanoma to the distant organs is a multistep process in which the tumor microenvironment (TME) may play an important role. However, the relationship between metastatic progression and TME is intricate. In the present study, using melanoma derivative cell lines OL (oligometastatic) and POL (polymetastatic) that differ in their metastatic colonization capability, we have elucidated a new mechanism involving “SEC23A-PF4-MAPK/ERK axis” in which PF4 transported by COPII hinders metastasis through inhibition of MAPK/ERK signaling pathway. Furthermore, SPARC can act cooperatively to enhance the inhibition of Pf4 on ERK phosphorylation and melanoma cell metastasis. Our findings show the possibility of targeting cancer cell secretome for therapeutic development.

The SARS-CoV-2/Receptor Axis in Heart and Blood Vessels: A Crisp Update on COVID-19 Disease with Cardiovascular Complications

The SARS-CoV-2 virus causing COVID-19 disease has emerged expeditiously in the world and has been declared pandemic since March 2020, by World Health Organization (WHO). The destructive effects of SARS-CoV-2 infection are increased among the patients with pre-existing chronic conditions and, in particular, this review focuses on patients with underlying cardiovascular complications. The expression pattern and potential functions of SARS-CoV-2 binding receptors and the attributes of SARS-CoV-2 virus tropism in a physio-pathological state of heart and blood vessel are precisely described. Of note, the atheroprotective role of ACE2 receptors is reviewed. A detailed description of the possible detrimental role of SARS-CoV-2 infection in terms of vascular leakage, including endothelial glycocalyx dysfunction and bradykinin 1 receptor stimulation is concisely stated. Furthermore, the potential molecular mechanisms underlying SARS-CoV-2 induced clot formation in association with host defense components, including activation of FXIIa, complements and platelets, endothelial dysfunction, immune cell responses with cytokine-mediated action are well elaborated. Moreover, a brief clinical update on patient with COVID-19 disease with underlying cardiovascular complications and those who had new onset of cardiovascular complications post-COVID-19 disease was also discussed. Taken together, this review provides an overview of the mechanistic aspects of SARS-CoV-2 induced devastating effects, in vital organs such as the heart and vessels.

IL-6 in inflammation, autoimmunity and cancer

IL-6 is involved both in immune responses and in inflammation, hematopoiesis, bone metabolism and embryonic development. IL-6 plays roles in chronic inflammation (closely related to chronic inflammatory diseases, autoimmune diseases and cancer) and even in the cytokine storm of corona virus disease 2019 (COVID-19). Acute inflammation during the immune response and wound healing is a well-controlled response, whereas chronic inflammation and the cytokine storm are uncontrolled inflammatory responses. Non-immune and immune cells, cytokines such as IL-1β, IL-6 and tumor necrosis factor alpha (TNFα) and transcription factors nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) play central roles in inflammation. Synergistic interactions between NF-κB and STAT3 induce the hyper-activation of NF-κB followed by the production of various inflammatory cytokines. Because IL-6 is an NF-κB target, simultaneous activation of NF-κB and STAT3 in non-immune cells triggers a positive feedback loop of NF-κB activation by the IL-6-STAT3 axis. This positive feedback loop is called the IL-6 amplifier (IL-6 Amp) and is a key player in the local initiation model, which states that local initiators, such as senescence, obesity, stressors, infection, injury and smoking, trigger diseases by promoting interactions between non-immune cells and immune cells. This model counters dogma that holds that autoimmunity and oncogenesis are triggered by the breakdown of tissue-specific immune tolerance and oncogenic mutations, respectively. The IL-6 Amp is activated by a variety of local initiators, demonstrating that the IL-6-STAT3 axis is a critical target for treating diseases.

STAT3, a Master Regulator of Anti-Tumor Immune Response

Immune cells in the tumor microenvironment regulate cancer growth. Thus cancer progression is dependent on the activation or repression of transcription programs involved in the proliferation/activation of lymphoid and myeloid cells. One of the main transcription factors involved in many of these pathways is the signal transducer and activator of transcription 3 (STAT3). In this review we will focus on the role of STAT3 and its regulation, e.g. by phosphorylation or acetylation in immune cells and how it might impact immune cell function and tumor progression. Moreover, we will review the ability of STAT3 to regulate checkpoint inhibitors.

CXCL4 contributes to host defense against acute Pseudomonas aeruginosa lung infection

Platelets have been implicated in pulmonary inflammation following exposure to bacterial stimuli. The mechanisms involved in the platelet-mediated host response to respiratory bacterial infection remain incompletely understood. In this study, we demonstrate that platelet-derived chemokine (C-X-C motif) ligand 4 (CXCL4) plays critical roles in a mouse model of acute bacterial pneumonia using Pseudomonas aeruginosa. Platelets are activated during P. aeruginosa infection, and mice depleted of platelets display markedly increased mortality and impaired bacterial clearance. CXCL4 deficiency impairs bacterial clearance and lung epithelial permeability, which correlate with decreased neutrophil recruitment to BALF. Interestingly, CXCL4 deficiency selectively regulates chemokine production, suggesting that CXCL4 has an impact on other chemokine expression. In addition, CXCL4 deficiency reduces platelet-neutrophil interactions in blood following P. aeruginosa infection. Further studies revealed that platelet-derived CXCL4 contributes to the P. aeruginosa-killing of neutrophils. Altogether, these findings demonstrate that CXCL4 is a vital chemokine that plays critical roles in bacterial clearance during P. aeruginosa infection through recruiting neutrophils to the lungs and intracellular bacterial killing.

MBD2-mediated Th17 differentiation in severe asthma is associated with impaired SOCS3 expression

T helper 17 (Th17) cells has proven to be crucial in the pathogenesis of severe asthma. Although it is known that Suppressor of cytokine signaling 3 (SOCS3) is involved in differentiation of Th17 cells but, how it affects severe asthma is uncertain. Since previous studies indicated that Methtyl-CpG binding domain protein 2 (MBD2) null mice was deficient in Th17 cell differentiation, the aim of the present study was to understand how MBD2 interacts with SOCS3 to regulate Th17 cell differentiation in severe asthma. Here, we show that SOCS3 expression was significantly decreased in Th17-mediated severe asthmatic mice, accompanied by elevated STAT3 phosphorylation and RORγt expression. Knock-down of SOCS3 promoted the differentiation of naïve T cells into Th17 cells through STAT3/RORγt pathway. Meanwhile, MBD2 was overexpressed in Th17-mediated severe asthmatic mice. Intervention of MBD2 expression lead to a negative change of SOCS3 expression, whereas the differentiation of Th17 cells showed positive change. In addition, MBD2 knockout (MBD2-KO) mice displayed increased SOCS3 expression and decreased Th17 differentiation after severe asthma modeling. Taken together, our results suggest that MBD2 might facilitate Th17 cell differentiation via down-regulating SOCS3 expression in severe asthma. These findings uncover new roles for SOCS3 and MBD2, and provide a potential target for treatment of severe asthma.

Platelet factor 4 is produced by subsets of myeloid cells in premetastatic lung and inhibits tumor metastasis

Bone marrow-derived myeloid cells can form a premetastatic niche and provide a tumor-promoting microenvironment. However, subsets of myeloid cells have also been reported to have anti-tumor properties. It is not clear whether there is a transition between anti- and pro- tumor function of these myeloid cells, and if so, what are the underlying molecular mechanisms. Here we report platelet factor 4 (PF4), or CXCL4, but not the other family members CXCL9, 10, and 11, was produced at higher levels in the normal lung and early stage premetastatic lungs but decreased in later stage lungs. PF4 was mostly produced by Ly6G+CD11b+ myeloid cell subset. Although the number of Ly6G+CD11b+ cells was increased in the premetastatic lungs, the expression level of PF4 in these cells was decreased during the metastatic progression. Deletion of PF4 (PF4 knockout or KO mice) led an increased metastasis suggesting an inhibitory function of PF4. There were two underlying mechanisms: decreased blood vessel integrity in the premetastatic lungs and increased production of hematopoietic stem/progenitor cells (HSCs) and myeloid derived suppressor cells (MDSCs) in tumor-bearing PF4 KO mice. In cancer patients, PF4 expression levels were negatively correlated with tumor stage and positively correlated with patient survival. Our studies suggest that PF4 is a critical anti-tumor factor in the premetastatic site. Our finding of PF4 function in the tumor host provides new insight to the mechanistic understanding of tumor metastasis.

CXCL4 is a novel inducer of human Th17 cells and correlates with IL-17 and IL-22 in psoriatic arthritis

CXCL4 regulates multiple facets of the immune response and is highly upregulated in various Th17-associated rheumatic diseases. However, whether CXCL4 plays a direct role in the induction of IL-17 production by human CD4+ T cells is currently unclear. Here, we demonstrated that CXCL4 induced human CD4+ T cells to secrete IL-17 that co-expressed IFN-γ and IL-22, and differentiated naïve CD4+ T cells to become Th17-cytokine producing cells. In a co-culture system of human CD4+ T cells with monocytes or myeloid dendritic cells, CXCL4 induced IL-17 production upon triggering by superantigen. Moreover, when monocyte-derived dendritic cells were differentiated in the presence of CXCL4, they orchestrated increased levels of IL-17, IFN-γ, and proliferation by CD4+ T cells. Furthermore, the CXCL4 levels in synovial fluid from psoriatic arthritis patients strongly correlated with IL-17 and IL-22 levels. A similar response to CXCL4 of enhanced IL-17 production by CD4+ T cells was also observed in patients with psoriatic arthritis. Altogether, we demonstrate that CXCL4 boosts pro-inflammatory cytokine production especially IL-17 by human CD4+ T cells, either by acting directly or indirectly via myeloid antigen presenting cells, implicating a role for CXCL4 in PsA pathology.

The prognostic significance of circulating serum amyloid A and CXC chemokine ligand 4 in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common pediatric bone cancer.  Despite advances in treatment regimens, the survival rate remains 60-70%.  There is an urgent need to identify prognostic biomarkers, so that targeted therapies can be developed to improve the outcome.

PROCEDURE

Our laboratory has previously identified that circulating serum amyloid A (SAA) and CXC chemokine ligand 4 (CXCL4) are upregulated in patients with OS.  In this study, we tested if they could be used as prognostic biomarkers.  We used enzyme-linked immunosorbent assays to measure their concentrations in serum samples (n = 233) and immunohistochemistry to examine their expressions in primary tumors (n = 37).  Prognostic significance of the serum concentrations and tumor expressions of the biomarkers was then evaluated.

RESULTS

Patients with "high SAA" and "low CXCL4" circulating levels at diagnosis significantly correlated with a worse outcome (HR = 1.68, P = 0.014), which was independent of the metastatic status.  These patients also exhibited a significantly higher rate of poor histologic response to chemotherapy.  Furthermore, low tumor expression of CXCL4 correlated with poor survival (HR = 3.57, P = 0.005).

CONCLUSIONS

Our results demonstrate that circulating SAA and CXCL4 may serve as prognostic biomarkers in OS.  Targeting CXCL4 has been reported, suggesting that it may be exploited as a therapeutic target in OS.

DNA methylation/hydroxymethylation in melanoma

Melanoma is a malignant tumor of melanocytes and is considered to be the most aggressive cancer among all skin diseases. The pathogenesis of melanoma has not been well documented, which may restrict the research and development of biomarkers and therapies. To date, several genetic and epigenetic factors have been identified as contributing to the development and progression of melanoma. Besides the findings on genetic susceptibilities, the recent progress in epigenetic studies has revealed that loss of the DNA hydroxymethylation mark, 5-hydroxymethylcytosine (5-hmC), along with high levels of DNA methylation at promoter regions of several tumor suppressor genes in melanoma, may serve as biomarkers for melanoma. Moreover, 5-Aza-2′-deoxycytidine, an epigenetic modifier causing DNA demethylation, and ten-eleven translocation family dioxygenase (TET), which catalyzes the generation of 5-hmC, demonstrate therapeutic potential in melanoma treatment. In this review, we will summarize the latest progress in research on DNA methylation/hydroxymethylation in melanoma, and we will discuss and provide insight for epigenetic biomarkers and therapies for melanoma. Particularly, we will discuss the role of DNA hydroxymethylation in melanoma infiltrating immune cells, which may also serve as a potential target for melanoma treatment.

Mean platelet volume as a marker for differentiating disease flare from infection in Behçet's disease

AIM

The aim of this study was to investigate the association between mean platelet volume (MPV) and clinical manifestations, disease activity or infection in patients with Behçet's disease (BD).

METHODS

In total, 193 patients diagnosed with BD according to the international criteria for BD were enrolled. Demographic data, clinical manifestations and laboratory results were collected by medical interviews and reviewing medical records.

RESULTS

The female : male ratio was 2 : 1 and the age of symptom onset was 32.2 ± 11.1 years. The age at diagnosis of BD was 44.7 ± 11.1 years and the follow-up duration was 4.7 ± 3.8 years. MPV at diagnosis were significantly lower than of age and sex-matched controls (8.2 ± 1.2 vs. 8.6 ± 1.2 fL, P < 0.0001). Lower MPV was not related to organ involvement except skin diseases. During follow-up, MPV was lower in BD flare than in stable BD (8.2 ± 1.4 vs. 9.1 ± 1.4 fL, P < 0.0001) in the same patients. MPVs were significantly higher in cases of accompanying infections than in those with both BD flare and stable BD (9.3 ± 1.4 vs. 8.1 ± 1.3 fL, P = 0.018 and 9.7 ± 1.4 vs. 8.8 ± 1.0 fL, P = 0.001, respectively).

CONCLUSIONS

MPV was significantly lower in patients with BD than controls. MPV declined in BD flare and increased in cases of infection in same patients. MPV may be useful as a marker of BD activity and its monitoring can be helpful for differentiating BD flare from infection in BD patients.

Human Trefoil Factor 3 induces the transcription of its own promoter through STAT3

Human trefoil factor 3 (hTFF3) is a small peptide of potential therapeutic value. The mechanisms underlying the transcriptional regulation of hTFF3 remain unclear. The purpose of this study was to identify the core functional elements for the self-induction action of hTFF3 and transcription factors. First, truncated promoters were constructed to identify the functional regions of the hTFF3 promoter. Next, point mutation, chromatin immunoprecipitation, RNA interference, and gene overexpression experiments were performed to analyze the transcriptional binding sites responsible for the self-induced transcription of hTFF3. Our results revealed the −1450 bp to −1400 bp fragment of the hTFF3 promoter was the functional region for the self-induction action of hTFF3. Bioinformatics analysis confirmed that a STAT3 binding site is present in the −1417 bp to −1409 bp region. Subsequently, site-directed mutagenesis analysis determined that this STAT3 binding site was critical for the self-induction effect of hTFF3. ChIP experiments confirmed that STAT3 binds to the hTFF3 promoter. STAT3 overexpression and knockdown experiments revealed that STAT3 enhanced the self-induction effect and the expression of hTFF3. This study confirmed that hTFF3 exhibits self-induction action, and that STAT3 is the key transcription factor to maintain the function of self-induction.

Multiple regulation pathways and pivotal biological functions of STAT3 in cancer

STAT3 is both a transcription activator and an oncogene that is tightly regulated under normal physiological conditions. However, abundant evidence indicates that STAT3 is persistently activated in several cancers, with a crucial position in tumor onset and progression. In addition to its traditional role in cancer cell proliferation, invasion, and migration, STAT3 also promotes cancer through altering gene expression via epigenetic modification, inducing epithelial–mesenchymal transition (EMT) phenotypes in cancer cells, regulating the tumor microenvironment, and promoting cancer stem cells (CSCs) self-renewal and differentiation. STAT3 is regulated not only by the canonical cytokines and growth factors, but also by the G-protein-coupled receptors, cadherin engagement, Toll-like receptors (TLRs), and microRNA (miRNA). Despite the presence of diverse regulators and pivotal biological functions in cancer, no effective therapeutic inventions are available for inhibiting STAT3 and acquiring potent antitumor effects in the clinic. An improved understanding of the complex roles of STAT3 in cancer is required to achieve optimal therapeutic effects.

Reg3g Promotes Pancreatic Carcinogenesis in a Murine Model of Chronic Pancreatitis

BACKGROUND

Regenerating islet-derived 3 (Reg3) is abnormally expressed in several human digestive system diseases, including chronic pancreatitis (CP) and pancreatic cancer (PC).

AIM

The purpose of this study was to clarify the mechanism of the enhanced expression of Reg3 in inflammation-induced PC.

METHODS

C57BL/6 mice were treated with caerulein for 6 weeks to induce CP and then injected with pReg3g--a lentivirus system encoding for murine Reg3g--accompanied by dimethylbenzanthracene to induce PC. We detected pancreatic histopathological characteristics, tumor-related gene expression, inflammation-associated pathway activation, serum biochemical indicators, and immunological cell activities.

RESULTS

The mice that developed CP after caerulein treatment were marked by pronounced histologic lesions, elevated serum amylase levels, and activation of inflammation-related pathways. Mice given a high dose of pReg3g developed PC by 16 weeks, with recognizable tumors in the pancreas. While, both the low and high doses of pReg3g produced higher transcription of c-fos, k-ras, cytokeratin-19, and proliferating cell nuclear antigen, and a lower expression of caspase-3 compared to pNEG controls. Additionally, the higher dose of pReg3g increased the expressions of pSTAT3, NFκB (p65), and SOCS3 methylation during PC development. In addition, mice treated with pReg3g displayed higher levels of serum IL10 and TGFβ and suppressed T lymphocyte proliferation and DC function.

CONCLUSION

The comprehensive analysis suggests enhanced Reg3g expression exacerbates PC in inflammation-associated cancer progression. Reg3g appears to promote CP-related PC in mice through multiple mechanisms, involving enhanced transcription of pancreatic tumor markers, repression of anti-tumor immunity, and activation of STAT3/p65 signal transduction pathways.

Epigenetic regulation in human melanoma: past and future

The development and progression of melanoma have been attributed to independent or combined genetic and epigenetic events. There has been remarkable progress in understanding melanoma pathogenesis in terms of genetic alterations. However, recent studies have revealed a complex involvement of epigenetic mechanisms in the regulation of gene expression, including methylation, chromatin modification and remodeling, and the diverse activities of non-coding RNAs. The roles of gene methylation and miRNAs have been relatively well studied in melanoma, but other studies have shown that changes in chromatin status and in the differential expression of long non-coding RNAs can lead to altered regulation of key genes. Taken together, they affect the functioning of signaling pathways that influence each other, intersect, and form networks in which local perturbations disturb the activity of the whole system. Here, we focus on how epigenetic events intertwine with these pathways and contribute to the molecular pathogenesis of melanoma.