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Purpose: G-CSF enhances colon cancer development. This study defines the prevalence and effects of increased G-CSF signaling in human colon cancers and investigates G-CSF inhibition as an immunotherapeutic strategy against metastatic colon cancer. Experimental Design: Patient samples were used to evaluate G-CSF and G-CSF receptor (G-CSFR) levels by IHC with sera used to measure G-CSF levels. Peripheral blood mononuclear cells were used to assess the rate of G-CSFR+ T cells and IFNγ responses to chronic ex vivo G-CSF. An immunocompetent mouse model of peritoneal metastasis (MC38 cells in C57Bl/6J) was used to determine the effects of G-CSF inhibition (αG-CSF) on survival and the tumor microenvironment (TME) with flow and mass cytometry. Results: In human colon cancer samples, the levels of G-CSF and G-CSFR are higher compared to normal colon tissues from the same patient. High patient serum G-CSF is associated with increases in markers of poor prognosis, (e.g., VEGF, IL6). Circulating T cells from patients express G-CSFR at double the rate of T cells from controls. Prolonged G-CSF exposure decreases T cell IFNγ production. Treatment with αG-CSF shifts both the adaptive and innate compartments of the TME and increases survival (HR, 0.46; P = 0.0237) and tumor T-cell infiltration, activity, and IFNγ response with greater effects in female mice. There is a negative correlation between serum G-CSF levels and tumor-infiltrating T cells in patient samples from women. Conclusions: These findings support G-CSF as an immunotherapeutic target against colon cancer with greater potential benefit in women.

Supplementary Figure S2

Supplementary Table 1: CyTOF antibody panel and source

Purpose:G-CSF enhances colon cancer development. This study defines the prevalence and effects of increased G-CSF signaling in human colon cancers and investigates G-CSF inhibition as an immunotherapeutic strategy against metastatic colon cancer.Experimental Design:Patient samples were used to evaluate G-CSF and G-CSF receptor (G-CSFR) levels by IHC with sera used to measure G-CSF levels. Peripheral blood mononuclear cells were used to assess the rate of G-CSFR+ T cells and IFNγ responses to chronic ex vivo G-CSF. An immunocompetent mouse model of peritoneal metastasis (MC38 cells in C57Bl/6J) was used to determine the effects of G-CSF inhibition (αG-CSF) on survival and the tumor microenvironment (TME) with flow and mass cytometry.Results:In human colon cancer samples, the levels of G-CSF and G-CSFR are higher compared to normal colon tissues from the same patient. High patient serum G-CSF is associated with increases in markers of poor prognosis, (e.g., VEGF, IL6). Circulating T cells from patients express G-CSFR at double the rate of T cells from controls. Prolonged G-CSF exposure decreases T cell IFNγ production. Treatment with αG-CSF shifts both the adaptive and innate compartments of the TME and increases survival (HR, 0.46; P = 0.0237) and tumor T-cell infiltration, activity, and IFNγ response with greater effects in female mice. There is a negative correlation between serum G-CSF levels and tumor-infiltrating T cells in patient samples from women.Conclusions:These findings support G-CSF as an immunotherapeutic target against colon cancer with greater potential benefit in women.

Background Women with colorectal cancer (CRC) have a significant survival advantage over men. Sex influences on the tumour microenvironment (TME) are not well characterised, despite the importance of immune response in CRC. We hypothesised that sex-divergent immune responses could contribute to survival. Methods Using a murine model of metastatic CRC, we examined T cells, macrophages, and cytokines locally and systemically. TME and serum cytokines were measured by multiplex bead-based arrays, while FCA was used to identify cells and phenotypes. IHC provided spatial confirmation of T cell infiltration. Results Females had increased survival and T cell infiltration. CD8, CD4 and Th2 populations correlated with longer survival. Males had increased serum levels of chemokines and inflammation-associated cytokines. Within the TME, males had lower cytokine levels than females, and a shallower cytokine gradient to the periphery. Female tumours had elevated IL-10+ macrophages, which correlated with survival. Conclusions These data demonstrate survival-associated differences in the immune response of males and females to metastatic CRC. Females showed changes in cytokine production accompanied by increased immune cell populations, biased toward Th2-axis phenotypes. Key differences in the immune response to CRC correlated with survival in this model. These differences support a multi-faceted shift across the TME.

Colorectal cancer (CRC) development and progression is associated with chronic inflammation. We have identified the MAPK-activated protein kinase 2 (MK2) pathway as a primary mediator of inflammation in CRC. MK2 signaling promotes production of proinflammatory cytokines IL-1β, IL-6 and TNF-α. These cytokines have been implicated in tumor growth, invasion and metastasis. For the first time, we investigate whether MK2 inhibition can improve outcome in two mouse models of CRC. In our azoxymethane/dextran sodium sulfate (AOM/DSS) model of colitis-associated CRC, MK2 inhibitor treatment eliminated murine tumor development. Using the implanted, syngeneic murine CRC cell line CT26, we observe significant tumor volume reduction following MK2 inhibition. Tumor cells treated with MK2 inhibitors produced 80% less IL-1β, IL-6 and TNF-α and demonstrated decreased invasion. Replenishment of downstream proinflammatory MK2-mediated cytokines (IL-1β, IL-6 and TNF-α) to tumors led to restoration of tumor proliferation and rapid tumor regrowth. These results demonstrate the importance of MK2 in driving proinflammatory cytokine production, its relevance to in vivo tumor proliferation and invasion. Inhibition of MK2 may represent an attractive therapeutic target to suppress tumor growth and progression in patients.

Colorectal cancer is the 2nd leading cause of cancer-related deaths in the world. The mechanisms underlying CRC development, progression, and resistance to treatment are complex and not fully understood. The immune response in the tumor microenvironment has been shown to play a significant role in many cancers, including colorectal cancer. Colony-stimulating factor 3 (CSF3) has been associated with changes to the immune environment in colorectal cancer animal models. We hypothesized that CSF3 signaling would correlate with pro-tumor tumor microenvironment changes associated with immune infiltrate and response. We utilized publicly available datasets to guide future mechanistic studies of the role CSF3 and its receptor (CSF3R) play in colorectal cancer development and progression. Here, we use bioinformatics data and mRNA from patients with colon (n = 242) or rectal (n = 92) cancers, obtained from The Cancer Genome Atlas Firehose Legacy dataset. We examined correlations of CSF3 and CSF3R expression with patient demographics, tumor stage and consensus molecular subtype classification. Gene expression correlations, cell type enrichment, Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data scores and Gene Ontology were used to analyze expression of receptor and ligand, tumor microenvironment infiltration of immune cells, and alterations in biological pathways. We found that CSF3 and CSF3R expression is highest in consensus molecular subtype 1 and consensus molecular subtype 4. Ligand and receptor expression are also correlated with changes in T cell and macrophage signatures. CSF3R significantly correlates with a large number of genes that are associated with poor colorectal cancer prognosis.

Colorectal cancer (CRC) is the third most common cancer, and is associated closely with inflammation before and after development. Macrophages participate in colitis and colitis-associated colorectal cancers. M1 macrophages contribute to colitis directly through the production of proinflammatory cytokines, such as IL-1, IL-6, and TNF-α, and through activation of proinflammatory phenotypes in other cell types, including T cells. In cancer, both M1 and M2 cells participate in development and progression, through cytokine production, changes in cell signaling, and activation of T cells. We have identified mitogen-activated protein kinase-activated protein kinase 2 (MK2) as a regulator of macrophages during inflammation-associated cancers. MK2 is a proinflammatory kinase that promotes the production of IL-1, IL-6, and TNF-α. MK2 -/- mice show reduced levels of macrophages and macrophage-associated chemokines and proinflammatory cytokines. Most significantly, MK2 -/- mice do not develop neoplasms under an inflammatory model of CRC. Addition of MK2 +/+ macrophages to MK2 -/- mice increases macrophage-associated cytokines. In wild type mice, both cytokines and tumor burdens increase. This data supports the role of MK2 in macrophages during inflammation-associated CRC.

Chronic inflammation is a risk factor for colorectal cancer. The MAPK-activated protein kinase 2 (MK2) pathway controls multiple cellular processes including p38-dependent inflammation. This is the first study to investigate the role of MK2 in development of colitis-associated colon cancer (CAC) using the AOM/DSS model. Herein, we demonstrate that MK2−/− mice are highly resistant to neoplasm development when exposed to AOM/DSS, while wild type C57BL/6 develop multiple neoplasms with the same treatment. MK2-specific cytokines IL-1, IL-6 and TNF-α were substantially decreased in AOM/DSS treated MK2−/− mouse colon tissues compared to wild type mice which coincided with a marked decrease in macrophage influx. Restoring MK2-competent macrophages by injecting wild type (WT) bone marrow derived macrophages into MK2−/− mice led to partial restoration of inflammatory cytokine production with AOM/DSS treatment; however, was not sufficient to induce neoplasm development. Our results indicate that MK2 functions as an inflammatory regulator to promote colonic neoplasm development and may be a potential target for CAC.

// Katherine T. Morris 1 , Eliseo F. Castillo 2 , Anita L. Ray 2 , Lea L. Weston 2 , Robert A. Nofchissey 2 , Joshua A. Hanson 3 , Von G. Samedi 3 , Irina V. Pinchuk 4 , Laurie G. Hudson 5 , Ellen J. Beswick 2 1 Department of Surgery, University of New Mexico, Albuquerque, New Mexico, USA 2 Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, New Mexico, USA 3 Department of Pathology, University of New Mexico, Albuquerque, New Mexico, USA 4 Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA 5 Department of Pharmaceutical Sciences, University of New Mexico, Albuquerque, New Mexico, USA Correspondence to: Ellen J. Beswick, e-mail: ebeswick@salud.unm.edu Keywords: G-CSF, colorectal cancer, NK cells, macrophages, Th1 Received: April 03, 2015 Accepted: May 21, 2015 Published: June 04, 2015 ABSTRACT Granulocyte colony-stimulating factor (G-CSF) is a cytokine that is highly expressed in human and mouse colorectal cancers (CRC). We previously reported that G-CSF stimulated human CRC cell growth and migration, therefore in this study we sought to examine the therapeutic potential of anti-G-CSF treatment for CRC. G-CSF is known to mobilize neutrophils, however its impact on other immune cells has not been well examined. Here, we investigated the effects of therapeutic anti-G-CSF treatment on CRC growth and anti-tumor immune responses. C57BL/6 mice treated with azoxymethane/dextran sodium sulfate (AOM/DSS) to induce neoplasms were administered anti-G-CSF or isotype control antibodies three times a week for three weeks. Animals treated with anti-G-CSF antibodies had a marked decrease in neoplasm number and size compared to the isotype control group. Colon neutrophil and macrophage frequency were unchanged, but the number of macrophages producing IL-10 were decreased while IL-12 producing macrophages were increased. NK cells were substantially increased in colons of anti-G-CSF treated mice, along with IFNγ producing CD4 + and CD8 + T cells. These studies are the first to indicate a crucial role for G-CSF inhibition in promoting protective anti-tumor immunity, and suggest that anti-G-CSF treatment is a potential therapeutic approach for CRC.

Introduction: Colorectal cancer is the third most common malignancy diagnosed for both men and women in the United States of America. High levels of inflammatory cytokines in colorectal tumors cause increased growth and invasion and carry a higher risk of metastasis. Identifying new targets to control inflammation is important for developing improved treatment approaches. Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a regulator of pro-inflammatory cytokines that may promote colorectal tumor progression. MK2 signaling is known to induce IL-1, IL-6, and TNF-α production. These pro-inflammatory cytokines are associated with CRC development, invasion, and metastasis. We hypothesized that the MK2 pathway could be an important component of CRC growth, invasion and tumor regrowth. Methods: To investigate this pathway, CT26 CRC cells were examined. Cells were flank-injected into Balb/c mice with and without MK2 inhibitor treatment. At day 19 after tumor injection, tumors were harvested and measured using calipers. Cytokines were quantitated by multiplex bead array in organ culture supernatants and in supernatants from tumor cells plated in fibronectin coated wells. In culture, tumor cell invasion was measured in scratch wound assays containing matrigel. Results: Treating CT26 cells with MK2 inhibitors markedly reduced tumor growth in mice by a mean of 60% compared to vehicle control treated cells. Inflammatory cytokines were also dramatically decreased with MK2 inhibition compared to controls by up to 80%. Cytokines affected included both known MK2 downstream cytokines (IL-1, IL-6, and TNF-α) and also chemokines such as MIP-1α and MCP-1 in both supernatants from cultured tumor cells and in organ culture supernatants. MK2 inhibition also decreased invasion of tumor cells in a cytokine dependent manner. Conclusions: The MK2 pathway regulates production of multiple pro-inflammatory cytokines in colorectal tumors, including several previously unreported chemokines. Inhibition of this pathway markedly decreases tumor growth and invasion. Thus, MK2 may be a promising tumor target to prevent colorectal cancer progression. Citation Format: Anita L. Ray, Amanda S. Peretti, Wade Johnson, Gregory Gan, Ellen J. Beswick. MK2 pathway blockade inhibits inflammatory cytokine production and colorectal cancer growth and invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2690. doi:10.1158/1538-7445.AM2017-2690