MK2 Regulates Macrophage Chemokine Activity and Recruitment to Promote Colon Tumor Growth

Increased Activity of MAPKAPK2 within Mesenchymal Cells as a Target for Inflammation-Associated Fibrosis in Crohn's Disease

BACKGROUND

Mesenchymal stromal cells are suggested to play a critical role in Crohn's disease [CD]-associated fibrosis. MAPKAPK2 [MK2] has emerged as a potential therapeutic target to reduce inflammation in CD. However, the cell-specific pattern of phospho-MK2 activation and its role in CD-associated fibrosis are unknown. The objectives of this study were to evaluate cell-specific changes in MK2 activity between predominantly inflammatory CD vs CD with fibrotic complications and define the role of stromal cell-specific MK2 activation in CD-associated fibrosis.

METHODS

CD tissue, CD tissue-derived mesenchymal stromal cells known as myo-/fibroblasts [CD-MFs], and fibroblast-specific MK2 conditional knockout [KO] mice were used.

RESULTS

In the inflamed area of predominantly inflammatory CD, high MK2 activity was equally distributed between mesenchymal and haematopoietic cells. By contrast, in CD with fibrotic complications, high MK2 activity was mostly associated with mesenchymal stromal cells. Using ex vivo CD tissue explants and an IL-10KO murine colitis model, we demonstrated that pro-fibrotic responses are significantly reduced by treatment with the MK2 inhibitor PF-3644022. Inhibition of MK2 activity in primary cultures of CD-MFs significantly reduced basal and TGF-β1-induced profibrotic responses. Using fibroblast-specific MK2 knockout mice in chronic dextran saline sulphate colitis, we demonstrated that fibroblast intrinsic MK2 signalling is among the key processes involved in the chronic inflammation-induced profibrotic responses.

CONCLUSIONS

Our data suggest that activation of MK2 within fibroblasts contributes to the chronic inflammation-induced fibrosis in CD and that targeting MK2 has potential for the development of novel therapeutic approaches for fibrosis in CD.

Remodeling tumor-associated macrophage for anti-cancer effects by rational design of irreversible inhibition of mitogen-activated protein kinase-activated protein kinase 2

Mitogen-activated protein kinase-activated protein kinase 2 (MK2) emerges as a pivotal target in developing anti-cancer therapies. The limitations of ATP-competitive inhibitors, due to insufficient potency and selectivity, underscore the urgent need for a covalent irreversible MK2 inhibitor. Our initial analyses of The Cancer Genome Atlas database revealed MK2's overexpression across various cancer types, especially those characterized by inflammation, linking it to poor prognosis and highlighting its significance. Investigating MK2's kinase domain led to the identification of a unique cysteine residue, enabling the creation of targeted covalent inhibitors. Compound 11 was developed, demonstrating robust MK2 inhibition (IC50 = 2.3 nM) and high selectivity. It binds irreversibly to MK2, achieving prolonged signal suppression and reducing pathological inflammatory cytokines in macrophages. Furthermore, compound 11 or MK2 knockdown can inhibit the tumor-promoting macrophage M2 phenotype in vitro and in vivo. In macrophage-rich tumor model, compound 11 notably slowed growth in a dose-dependent manner. These findings support MK2 as a promising anticancer target, especially relevant in cancers fueled by inflammation or dominated by macrophages, and provide compound 11 serving as an invaluable chemical tool for exploring MK2's functions.

MAPK-activated protein kinase 2 is associated with poor prognosis of glioma patients and immune inhibition in glioma

Introduction

An effective therapeutic method to noticeably improve the prognosis of glioma patients has not been developed thus far. MAPK-activated protein kinase 2 (MAPKAPK2) is a serine/threonine kinase, which is involved in tumorigenesis, tumor growth, metastasis, and the inflammatory process. The clinical significance and molecular function of MAPKAPK2 in glioma remain unclear.

Methods

MAPKAPK2 expression in human glioma tissues was detected by immunohistochemistry and analyzed from the transcriptome sequencing data in TCGA and CGGA. Prognostic nomogram was constructed to predict the survival risk of individual patients. GO and KEGG enrichment analyses were performed to analyze the function and pathways MAPKAPK2 involved. Single-cell RNA sequencing data was used to analyze the cell types in which MAPKAPK2 was enriched. Flow cytometry was used for cell cycle and apoptosis detection. The ability of cell proliferation and migration was analyzed by CCK8 and cell migration assay, respectively. Correlation analyses were performed to analyze the relationship of MAPKAPK2 with immune infiltration, immune regulators, chemokine, and chemokine receptors.

Results

MAPKAPK2 was not only aberrantly upregulated in glioma tissues but also correlated with poor clinical characteristics. Moreover, MAPKAPK2 was prevalent in isocitrate dehydrogenase (IDH) wild-type and 1p/19q non-codeletion glioma cohorts and predicted poor prognosis of glioma patients. MAPKAPK2 may be involved in cell proliferation, cell migration, DNA damage repair, and immune regulation in glioma. MAPKAPK2 was enriched in microglia/macrophages and malignant tumor cells. Further investigation into cellular function revealed that inhibiting MAPKAPK2 suppressed the proliferation and migration of glioblastoma multiforme (GBM) cells in vitro. The inhibition of MAPKAPK2 significantly induced the G1 cell cycle arrest and cell apoptosis of GBM cells. Consistent with the enriched function of MAPKAPK2 in immune regulation, MAPKAPK2 was correlated with immune cell infiltration in glioma tissues. Mechanistically, a series of immune regulators, immunomodulatory chemokine, and chemokine receptors were positively correlated with MAPKAPK2 expression.

Discussion

Our findings provide evidence of the clinical relevance of MAPKAPK2 in prognosis evaluation of glioma patients and highlight the underlying significance of MAPKAPK2 in glioma therapy.

Increased PKN2 and M2-Polarized Macrophages Promote HCT116 Cell Invasion

Colorectal cancer is the third most common malignant tumor, with highly invasive and metastatic potential in the later stage. This study investigated the role of PKN2 overexpression and M2-polarized macrophages in dictating the malignant phenotype of colorectal cancer cells. HCT116 colorectal cancer cell line with PKN2 overexpression was generated to investigate the functional role of PKN2. THP-1 cells were polarized into M2-like macrophages, and the co-culture system of THP-1/M2 cells and HCT116 cells was established to examine the impacts of M2-polairzed macrophages on the malignant phenotype of colorectal cancer cells. PKN2 overexpression promoted cell proliferation, migration and invasion in HCT116 colorectal cancer cells, and reduced spontaneous cell death in the cell culture. Besides, the presence of M2-polarized THP-1 cells significantly enhanced the aggressive phenotype of HCT116 cells. Both PKN2 overexpression and M2-polarized THP-1 cells increased the expression of NF-κB p65 in HCT116 cells, indicating that enhanced NF-κB signaling may contribute to the augmented aggressiveness of HCT116 cells. These findings suggest PKN2 as an oncogenic factor in colorectal cancer and that M2-polarized THP-1 cells may promote the progression of colorectal cancer by activating NF-κB signaling.

MK2 drives progression of pancreas and colon cancers by suppressing CD8+ T cell cytotoxic function and is a potential immunotherapy target

Background

Immune cell composition is a critical and dynamic component of the tumor microenvironment, which has an impact on immunosuppression and progression of cancer. T cells, especially CD8+ T cells, are one of the major immune cell types responsible for tumor cell killing employing receptor-ligand mediated apoptosis and/or releasing lytic granules among others. Accumulating evidence highlighted that adoptive transfer of activated and/or modified immune cells can enhance anti-tumorigenic immune responses and serve as promising therapy approach for patients with cancers. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a serine/threonine protein kinase, which controls production and secretion of numerous pro-inflammatory cytokines and chemokines involved in tumorigenesis. However, limited efforts have been made to learn how MK2 may affects CD8+ T cell action and function in the tumor microenvironment especially in gastrointestinal cancers.

Methods

To explore the therapeutic potential of MK2 in the immune response mediated by CD8+ T cells, RAG1 knockout mice with PK5L1940 and BRAF cells-derived allograft tumors were treated with WT or MK2 knockout CD8+ T cells. The phenotype of CD8+ T cells with MK2 depletion were evaluated in vitro. Immunofluorescence staining, real-time PCR and multiplex analysis were utilized to estimate the expression of apoptotic and lytic factors.

Results

Here, we show that CD8+ T cells with MK2 depletion prevent gastrointestinal cancer growth, which is accompanied by enhanced expression and secretion of factors related to apoptosis. Moreover, using in vitro and in vivo approaches, we found that depletion of MK2 lead to hyperactivation of CD8+ T cells and enhanced anti-tumor immunity.

Conclusion

Overall, we documented that MK2 drives the progression of gastrointestinal cancers and prevents immune response generated by CD8+ T cells suggesting potential implications of MK2 in the immunotherapy of gastrointestinal cancers.

Cellular stress induces non-canonical activation of the receptor tyrosine kinase EphA2 through the p38-MK2-RSK signaling pathway

The receptor tyrosine kinase EphA2 is overexpressed in malignant tumors. We previously reported that non-canonical EphA2 phosphorylation at Ser-897 was catalyzed by p90 ribosomal S6 kinase (RSK) via the MEK-ERK pathway in ligand- and tyrosine kinase-independent manners. Non-canonical EphA2 activation plays a key role in tumor progression; however, its activation mechanism remains unclear. In the present study, we focused on cellular stress signaling as a novel inducer of non-canonical EphA2 activation. p38, instead of ERK in the case of epidermal growth factor signaling, activated RSK-EphA2 under cellular stress conditions, including anisomycin, cisplatin and high osmotic stress. Notably, p38 activated the RSK-EphA2 axis via downstream MAPK-activated protein kinase 2 (MK2). Furthermore, MK2 directly phosphorylated both RSK1 Ser-380 and RSK2 Ser-386, critical residues for the activation of their N-terminal kinases, which is consistent with the result showing that the C-terminal kinase domain of RSK1 was dispensable for MK2-mediated EphA2 phosphorylation. Moreover, the p38-MK2-RSK-EphA2 axis promoted glioblastoma cell migration induced by temozolomide, a chemotherapeutic agent for the treatment of glioblastoma patients. Collectively, the present results reveal a novel molecular mechanism for non-canonical EphA2 activation under stress conditions in the tumor microenvironment.

MK2 Promotes the Development and Progression of Pancreatic Neuroendocrine Tumors Mediated by Macrophages and Metabolomic Factors

Cases of pancreatic neuroendocrine tumors (PNETs) are growing in number, and new treatment options are needed in order to improve patient outcomes. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a crucial regulator of cytokine/chemokine production. The significance of MK2 expression and signaling pathway mediated by MK2 in PNETs has not been investigated. To characterize the impact of MK2 on PNET growth, we used the RipTag2 transgenic murine model of PNETs, and we developed a primary PNET cell line for both in vitro and in vivo studies. In the transgenic murine model of PNETs, we found that MK2 inhibition improves survival of mice and prevents PNET progression. MK2 blockade abolished cytokine/chemokine production, which was related to macrophage function. A role for MK2 in the regulation of metabolic factor secretion in PNETs was identified, making this the first study to identify a potential role for the MK2 pathway in regulation of tumor metabolism. Moreover, using an in vitro approach and allograft model of PNETs, we were able to show that macrophages with MK2 depletion exhibit increased cytotoxicity against PNET cells and substantially decreased production of pro-inflammatory cytokines and chemokines, as well as metabolic factors. Taken together, our work identifies MK2 as a potent driver of immune response and metabolic effectors in PNETs, suggesting it is a potential therapeutic target for patients with PNETs.

Mechanism and strategies of immunotherapy resistance in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in the world. Although there are standard treatment options for CRC, most patients respond poorly to these treatments. Immunotherapies have gradually emerged due to the increasing awareness and understanding of tumor immunity, exhibiting good therapeutic efficacy in various cancers. Immunotherapies include cytokines, immune checkpoint inhibitors (ICIs), and adoptive cell therapies. In particular, ICIs, which are antibodies against cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed cell death 1 (PD-1), or its ligand PD-L1, have been successfully applied clinically for solid tumors, relieving the inhibitory effect of the tumor microenvironment on T cells. However, only a minority of patients with cancer achieve a durable clinical response during immunotherapy. Several factors restrict the efficacy of immunotherapy, leading to the development of drug resistance. In this review, we aimed to discuss the current status of immunotherapy for CRC and elaborate on the mechanisms that mediate resistance to immunotherapy and other potential therapeutic strategies.

A Naive Bayes model on lung adenocarcinoma projection based on tumor microenvironment and weighted gene co-expression network analysis

Based on the lung adenocarcinoma (LUAD) gene expression data from the cancer genome atlas (TCGA) database, the Stromal score, Immune score and Estimate score in tumor microenvironment (TME) were computed by the Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) algorithm. And gene modules significantly related to the three scores were identified by weighted gene co-expression network analysis (WGCNA). Based on the correlation coefficients and P values, 899 key genes affecting tumor microenvironment were obtained by selecting the two most correlated modules. It was suggested through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis that these key genes were significantly involved in immune-related or cancer-related terms. Through univariate cox regression and elastic network analysis, genes associated with prognosis of the LUAD patients were screened out and their prognostic values were further verified by the survival analysis and the University of ALabama at Birmingham CANcer (UALCAN) database. The results indicated that eight genes were significantly related to the overall survival of LUAD. Among them, six genes were found differentially expressed between tumor and control samples. And immune infiltration analysis further verified that all the six genes were significantly related to tumor purity and immune cells. Therefore, these genes were used eventually for constructing a Naive Bayes projection model of LUAD. The model was verified by the receiver operating characteristic (ROC) curve where the area under curve (AUC) reached 92.03%, which suggested that the model could discriminate the tumor samples from the normal accurately. Our study provided an effective model for LUAD projection which improved the clinical diagnosis and cure of LUAD. The result also confirmed that the six genes in the model construction could be the potential prognostic biomarkers of LUAD.

Therapeutic Approaches Targeting Proteins in Tumor-Associated Macrophages and Their Applications in Cancers

Tumor-associated macrophages (TAMs) promote tumor proliferation, invasion, angiogenesis, stemness, therapeutic resistance, and immune tolerance in a protein-dependent manner. Therefore, the traditional target paradigms are often insufficient to exterminate tumor cells. These pro-tumoral functions are mediated by the subsets of macrophages that exhibit canonical protein markers, while simultaneously having unique transcriptional features, which makes the proteins expressed on TAMs promising targets during anti-tumor therapy. Herein, TAM-associated protein-dependent target strategies were developed with the aim of either reducing the numbers of TAMs or inhibiting the pro-tumoral functions of TAMs. Furthermore, the recent advances in TAMs associated with tumor metabolism and immunity were extensively exploited to repolarize these TAMs to become anti-tumor elements and reverse the immunosuppressive tumor microenvironment. In this review, we systematically summarize these current studies to fully illustrate the TAM-associated protein targets and their inhibitors, and we highlight the potential clinical applications of targeting the crosstalk among TAMs, tumor cells, and immune cells in anti-tumor therapy.

MAPK-Activated Protein Kinases: Servant or Partner?

Mitogen-activated protein kinase (MAPK)-activated protein kinases (MAPKAPKs) are defined by their exclusive activation by MAPKs. They can be activated by classical and atypical MAPKs that have been stimulated by mitogens and various stresses. Genetic deletions of MAPKAPKs and availability of highly specific small-molecule inhibitors have continuously increased our functional understanding of these kinases. MAPKAPKs cooperate in the regulation of gene expression at the level of transcription; RNA processing, export, and stability; and protein synthesis. The diversity of stimuli for MAPK activation, the cross talk between the different MAPKs and MAPKAPKs, and the specific substrate pattern of MAPKAPKs orchestrate immediate-early and inflammatory responses in space and time and ensure proper control of cell growth, differentiation, and cell behavior. Hence, MAPKAPKs are promising targets for cancer therapy and treatments for conditions of acute and chronic inflammation, such as cytokine storms and rheumatoid arthritis. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Complex Network between Inflammation and Colorectal Cancer: A Systematic Review of the Literature

Simple Summary

Colorectal cancer is one of the most diffuse malignant pathologies, and many factors are involved in its genesis. Among these factors, inflammation plays an important role. Many molecules are involved in inflammation processes and are linked in different pathways, either in the sense of pro-tumorigenesis or anti-tumorigenic action. This review was conducted with the aim to review in a single paper the majority of actual knowledge in the literature and to comprehend inflammation patterns for better clinical and surgical management of patients.

Abstract

Background: colorectal cancer (CRC) has a multifactorial etiology which comprises microbiota, genetic predisposition, diet, environmental factors, and last but not least, a substantial contribution by inflammation. The aim of this study is to conduct a systematic review of the literature regarding the strong link between inflammation and colorectal cancer. Methods: A systematic review of the literature on PubMed (Medline), Scopus, Cochrane and EMBase databases was performed, following the PRISMA 2020 guidelines. Each paper was reviewed by two groups of researchers in a single-blind format by using a pre-planned Microsoft^© Excel^® grid. Results: Using automated research filters, 14,566 studies were included, but 1% was found significant by the reviewers. Seventy pathways of inflammation were described in the sequence of inflammation-carcinogenesis, and anti-tumorigenic molecules were also found. Conclusion: several studies suggest a strong role of inflammation in the tumorigenesis of colorectal cancer through different pathways: this may have a diagnostic and clinical role and also therapeutic purpose in preventing carcinogenesis by treating inflammation. In vitro tests support this theory, even if many other clinical trials are necessary. The present paper was registered in the OpenScience Framework registry (Identifier: DOI 10.17605/OSF.IO/2KG7T).

Granulocyte colony-stimulating factor promotes an aggressive phenotype of colon and breast cancer cells with biochemical changes investigated by single-cell Raman microspectroscopy and machine learning analysis

Granulocyte colony-stimulating factor (G-CSF) is produced at high levels in several cancers and is directly linked with metastasis in gastrointestinal (GI) cancers. In order to further understand the alteration of molecular compositions and biochemical features triggered by G-CSF treatment at molecular and cell levels, we sought to investigate the long term treatment of G-CSF on colon and breast cancer cells measured by label-free, non-invasive single-cell Raman microspectroscopy. Raman spectrum captures the molecule-specific spectral signatures ("fingerprints") of different biomolecules presented on cells. In this work, mouse breast cancer line 4T1 and mouse colon cancer line CT26 were treated with G-CSF for 7 weeks and subsequently analyzed by machine learning based Raman spectroscopy and gene/cytokine expression. The principal component analysis (PCA) identified the Raman bands that most significantly changed between the control and G-CSF treated cells. Notably, here we proposed the concept of aggressiveness score, which can be derived from the posterior probability of linear discriminant analysis (LDA), for quantitative spectral analysis of tumorigenic cells. The aggressiveness score was effectively applied to analyze and differentiate the overall cell biochemical changes of G-CSF-treated two model cancer cells. All these tumorigenic progressions suggested by Raman analysis were confirmed by pro-tumorigenic cytokine and gene analysis. A high correlation between gene expression data and Raman spectra highlights that the machine learning based non-invasive Raman spectroscopy offers emerging and powerful tools to better understand the regulation mechanism of cytokines in the tumor microenvironment that could lead to the discovery of new targets for cancer therapy.

Mitogen-activated protein kinase-activated protein kinase-2 (MK2) and its role in cell survival, inflammatory signaling, and migration in promoting cancer

Cancer and the immune system share an intimate relationship. Chronic inflammation increases the risk of cancer occurrence and can also drive inflammatory mediators into the tumor microenvironment enhancing tumor growth and survival. The p38 MAPK pathway is activated both acutely and chronically by stress, inflammatory chemokines, chronic inflammatory conditions, and cancer. These properties have led to extensive efforts to find effective drugs targeting p38, which have been unsuccessful. The immediate downstream serine/threonine kinase and substrate of p38 MAPK, mitogen-activated-protein-kinase-activated-protein-kinase-2 (MK2) protects cells against stressors by regulating the DNA damage response, transcription, protein and messenger RNA stability, and motility. The phosphorylation of downstream substrates by MK2 increases inflammatory cytokine production, drives an immune response, and contributes to wound healing. By binding directly to p38 MAPK, MK2 is responsible for the export of p38 MAPK from the nucleus which gives MK2 properties that make it unique among the large number of p38 MAPK substrates. Many of the substrates of both p38 MAPK and MK2 are separated between the cytosol and nucleus and interfering with MK2 and altering this intracellular translocation has implications for the actions of both p38 MAPK and MK2. The inhibition of MK2 has shown promise in combination with both chemotherapy and radiotherapy as a method for controlling cancer growth and metastasis in a variety of cancers. Whereas the current data are encouraging the field requires the development of selective and well tolerated drugs to target MK2 and a better understanding of its effects for effective clinical use.

Tumor-Associated Macrophages (TAMs) in Colorectal Cancer (CRC): From Mechanism to Therapy and Prognosis

Colorectal cancer (CRC) is a malignant tumor in the digestive system whose incidence and mortality is high-ranking among tumors worldwide. The initiation and progression of CRC is a complex process involving genetic alterations in cancer cells and multiple factors from the surrounding tumor cell microenvironment. As accumulating evidence has shown, tumor-associated macrophages (TAMs)—as abundant and active infiltrated inflammatory cells in the tumor microenvironment (TME)—play a crucial role in CRC. This review focuses on the different mechanisms of TAM in CRC, including switching of phenotypical subtypes; promoting tumor proliferation, invasion, and migration; facilitating angiogenesis; mediating immunosuppression; regulating metabolism; and interacting with the microbiota. Although controversy remains in clinical evidence regarding the role of TAMs in CRC, clarifying their significance in therapy and the prognosis of CRC may shed new light on the optimization of TAM-centered approaches in clinical care.

T lymphocyte and monocyte subsets are dysregulated in type 1 diabetes patients with peripheral neuropathic pain

Diabetic neuropathic pain is a common and devastating complication of type 1 diabetes, but the mechanism by which it develops and persists is yet to be fully elucidated. This study utilised high-dimensional suspension mass cytometry in a pilot cohort to investigate differences in peripheral blood immunophenotypes between type 1 diabetes patients with (n ​= ​9) and without (n ​= ​9) peripheral neuropathic pain. The abundance and activation of several leukocyte subsets were investigated with unsupervised clustering approaches FlowSOM and SPADE, as well as by manual gating. Major findings included a proportional increase in CD4+ central memory T cells and an absolute increase in classical monocytes, non-classical monocytes, and mature natural killer cells in type 1 diabetes patients with pain compared to those without pain. The expression of CD27, CD127, and CD39 was upregulated on select T cell populations, and the phosphorylated form of pro-inflammatory transcription factor MK2 was upregulated across most populations. These results provide evidence that distinct immunological signatures are associated with painful neuropathy in type 1 diabetes patients. Further research may link these changes to mechanisms by which pain in type 1 diabetes is initiated and maintained, paving the way for much needed targeted treatments.

MicroRNA-24-3p Inhibits Microglia Inflammation by Regulating MK2 Following Spinal Cord Injury

Spinal cord injury (SCI) is a functional impairment of the spinal cord caused by external forces, accompanied by limb movement disorders and permanent paralysis, which seriously lowers the life quality of SCI patients. Secondary injury caused by inflammation attenuated the therapeutic effects of SCI. Therefore, the exploration of biomarkers associated with the inflammatory response following SCI might provide novel therapy strategy against SCI.SCI rat model was established as previously reported and evaluated by BBB score. The expression of microRNA-24-3p (miR-24-3p) and MAPK-activated protein kinase 2 (MK2) in spinal cord tissues of SCI rats and HAPI cells was analyzed by qRT-PCR. Protein expression of MK2, ionized calcium-binding adapter molecule-1 (Iba-1), tumor necrosis factor-alpha (TNF-α), and interleukin-1β (IL-1β) was assessed by western blot assay. The release of inflammatory cytokines TNF-α and IL-1β was measured by enzyme-linked immunosorbent assay (ELISA). The interaction between miR-24-3p and MK2 was examined by the luciferase reporter system. Basso-Beattie-Bresnahan (BBB) score dramatically reduced in rats following SCI compared with sham rats. Moreover, the expression of miR-24-3p was down-regulated, while MK2 was up-regulated in the spinal cord tissues of SCI rats and LPS-induced microglia cells compared with the corresponding control group. Luciferase reporter system confirmed the interaction between miR-24-3p and MK2. In addition, miR-24-3p upregulation or MK2 knockdown attenuated LPS induced activation of microglial cells and expression of inflammatory cytokine TNF-α and IL-1β. Besides, we discovered that miR-24-3p regulated inflammation of highly aggressively proliferating immortalized (HAPI) cells by targeting MK2.In our study, we clarified that miR-24-3p repressed inflammation of microglia cells following SCI by regulating MK2, thereby providing promising biomarkers for SCI therapy.

G-CSF and G-CSFR Induce a Pro-Tumorigenic Macrophage Phenotype to Promote Colon and Pancreas Tumor Growth

Tumor-associated macrophages (TAMs) in the gastrointestinal tumor microenvironment (TME) are known to polarize into populations exhibiting pro- or anti-tumoral activity in response to stimuli such as growth factors and cytokines. Our previous work has recognized granulocyte colony-stimulating factor (G-CSF) as a cytokine capable of influencing immune cells of the TME exhibiting pro-tumoral activity. Here, we aimed to focus on how G-CSF regulates TAM phenotype and function and the effects on gastrointestinal (GI) tumor progression. Thus, wildtype (WT) and G-CSFR^-/- macrophages were examined for cytokine production, gene expression, and transcription factor activity. Adoptive transfer of WT or G-CSFR^-/- macrophages into tumor-bearing mice was performed to study their influence in the progression of colon (MC38) and pancreatic (PK5L1940) tumor mouse models. Finally, the difference in cytotoxic potential between WT and G-CSFR^-/- macrophages was examined both in vitro and in vivo. Our results indicate that G-CSF promotes increased IL-10 production and decreased IL-12 production, which was reversed in G-CSFR^-/- macrophages for a pro-inflammatory phenotype. Furthermore, G-CSFR^-/- macrophages were characterized by higher levels of NOS2 expression and NO production, which led to greater tumor related cytotoxicity both in vitro and in vivo. Our results suggest that in the absence of G-CSFR, macrophage-related tumor cytotoxicity was amplified. These findings, along with our previous reports, pinpoint G-CSF /G-CSFR as a prominent target for possible clinical applications that aim to control the TME and the GI tumor progression.

Integrative Analysis of MicroRNAs and mRNAs in LPS-Induced Macrophage Inflammation Based on Adipose Tissue Stem Cell Therapy

Severe inflammation can lead to multiple organ dysfunction syndrome, which has high mortality. Adipose-derived stem cells have been shown to affect the inflammatory response of macrophages. However, the molecular mechanism of the anti-inflammatory capacity of adipose-derived stem cells (ADSCs) remains to be understood. In the present study, a macrophage inflammation model was established by LPS, and treated with different volumes of ADSC supernatant. Then, we investigated the key genes in the LPS group and treatment group by RT-PCR, RNA sequencing technology, and bioinformatics analysis. A total of 26 miRNAs and 11,882 mRNAs were differentially expressed between them. The expression of 15 of the miRNAs (9 upregulated and 6 downregulated) was confirmed by RT-PCR. GO and KEGG pathway analyses of the targets of the 9 significantly upregulated miRNAs showed that they were related to immune system process, inflammatory response, lipopolysaccharide, and TNF-α, NF-κB, Toll-like receptor, and MAPK signaling pathways. Moreover, a miRNA-mRNA network also revealed 8 important genes (Mapkapk2, Sepp1, Cers6, Snn, ZfP568, Ccdc93, Pofut1, Pik3cd). We finally confirmed the expression of these 8 targeted genes by performing the RT-PCR analysis. This study may provide a new understanding of the molecular mechanism of ADSCs in the inflammatory response related to multiple miRNAs and mRNAs.

The MK2 pathway is linked to G-CSF, cytokine production and metastasis in gastric cancer: a novel intercorrelation analysis approach

Background

Gastric cancer is associated with chronic inflammation, but there is still much to understand about the tumor microenvironment and the underlying tumor-promoting mechanisms. The Map kinase-activated protein kinase 2 (MK2) pathway is a regulator of inflammatory cytokine production that we have been studying in gastrointestinal cancers. Here, we set out to determine the significance of this gene in gastric cancer along with its downstream mediators and if there were differences in the primary tumors with and without metastasis.

Methods

Human gastric cancer tissues with and without metastasis were examined for MK2 expression and cytokine profile in organ culture supernatants. Advanced statistical methods including a lower triangular correlation matrix, novel rooted correlation network, linear and logistic regression modeling along with Kruskal–Wallis testing with Sidak correction for multiple testing were applied to gain understanding of cytokines/chemokines linked to metastasis.

Results

The MK2 pathway is strongly linked with metastasis and a panel of cytokines. Gene expression was able to classify gastric cancer metastasis 85.7% of the time. A significant association with a panel of cytokines was found, including G-CSF, GM-CSF, Mip-1β, IFN-α, MCP-1, IL-1β, IL-6, and TNF-α. Mip-1β was found to have the strongest association with MK2 and metastasis after Sidak correction for multiple testing.

Conclusions

MK2 gene expression and a novel associated cytokine panel are linked to gastric cancer metastasis. G-CSF is the strongest cytokine to differentiate between metastasis and non-metastasis patients and had the lowest P value, while Mip-1β showed the strongest association with MK2 and metastasis after Sidak correction. MK2 and associated cytokines are potential biomarkers for gastric cancer metastasis. The novel intercorrelation analysis approach is a promising method for understanding the complex nature of cytokine/chemokine regulation and links to disease outcome.