Immune-related adverse events (irAEs), particularly colitis, are major limitations of immune checkpoint inhibitor (ICI) therapy, but their mechanisms remain poorly understood. Here we show that endogenous autoantibodies (AAbs) can promote ICI-associated colitis through Fcγ receptor-dependent pathways. IgG from melanoma patients treated with pembrolizumab, nivolumab, or ipilimumab, with or without severe colitis, was transferred into wild-type or humanized FcγR (hFcγR) mice receiving comparable ICI therapy. Wild-type mice did not develop changes in the colon. In contrast, hFcγR mice given IgG from patients with colitis developed colon inflammation marked by a significant increase in submucosal lymphocyte infiltration, goblet cell loss, and circulating cytokines, including IL-1β, IL-17a, and IL-22. Single-cell RNA sequencing identified an IgG-regulated inflammatory network involving IFNγ-producing ILC1, Th1 and cytotoxic T cells, IL-1β+ M1 macrophages, plasma B cells/plasmablasts, and IL-22-producing ILC3-LTi cells. Patient serum autoantibody profiling further identified CCR5 and CXCR4 receptors as candidate immune-related targets associated with ICC susceptibility. Immune-related adverse events (irAEs), particularly colitis, are major limitations of immune checkpoint inhibitor (ICI) therapy, but their mechanisms remain poorly understood. Here we show that endogenous autoantibodies (AAbs) can promote ICI-associated colitis through Fc gamma receptor (FcgR)-dependent pathways. IgG from melanoma patients treated with pembrolizumab, nivolumab, or ipilimumab, with or without severe colitis, was transferred into wild-type or humanized FcgR (hFcgR) mice receiving comparable ICI therapy. Wild-type mice did not develop changes in the colon. In contrast, hFcgR mice given IgG from patients with colitis developed colon inflammation marked by a significant increase in submucosal lymphocyte infiltration, goblet cell loss, and circulating cytokines, including IL-6, IL-17, and IL-22. Single-cell RNA sequencing identified an IgG-regulated inflammatory network involving IFNg-producing ILC1, Th1 and cytotoxic T cells, IL-1betta-M1 macrophages, plasma B cells/plasmablasts, and IL-22-producing ILC3-LTi cells. Patient serum autoantibody profiling further identified CCR5 and CXCR4 receptors as candidate immune-related targets associated with ICC susceptibility.

Background: We previously reported a higher incidence of a pathogenic germline variant in the kinase insert domain receptor (KDR) in melanoma patients compared to the general population. Here, we dissect the impact of this genotype on melanoma tumor growth kinetics, tumor phenotype, and response to treatment with immune checkpoint inhibitors (ICIs) or targeted therapy. Methods: The KDR genotype was determined and the associations between the KDR Q472H variant (KDR-Var), angiogenesis, tumor immunophenotype, and response to MAPK inhibition or ICI treatment were examined. Melanoma B16 cell lines were transfected with KDR-Var or KDR wild type (KDR-WT), and the differences in tumor kinetics were evaluated. We also examined the impact of KDR-Var on the response of melanoma cells to a combination of VEGFR inhibition with MAPKi. Results: We identified the KDR-Var genotype in 81/489 (37%) patients, and it was associated with a more angiogenic (p = 0.003) and immune-suppressive tumor phenotype. KDR-Var was also associated with decreased PFS to MAPKi (p = 0.022) and a trend with worse PFS to anti-PD1 therapy (p = 0.06). KDR-Var B16 murine models had increased average tumor volume (p = 0.0027) and decreased CD45 tumor-infiltrating lymphocytes (p = 0.0282). The anti-VEGFR treatment Lenvatinib reduced the tumor size of KDR-Var murine tumors (p = 0.0159), and KDR-Var cells showed synergistic cytotoxicity to the combination of dabrafenib and lenvatinib. Conclusions: Our data demonstrate a role of germline KDR-Var in modulating melanoma behavior, including response to treatment. Our data also suggest that anti-angiogenic therapy might be beneficial in patients harboring this genotype, which needs to be tested in clinical trials.

Supplementary Materials and Methods. Description of additional methods and procedures used in the study.

Supplementary Figure and Table Legend. Legend for Supplementary Figures S1-S8 and Supplementary Tables S1-S4.

Supplementary Table S3. Excel file containing the GO-term analysis with all differentially expressed genes.

Supplementary Table S1. Key characteristics of the cell lines used in this study.

Supplementary Table S2. Excel-file with all differentially expressed genes.

Supplementary Table S4. Loss of oncogenic B-Raf signaling induces transcripts associated with intestinal differentiation.

Supplementary Figures S1-S8. Effects of oncogenic B-Raf signaling on the phenotype of HT29 and Caco2-tet cells in conventional tissue culture (S1); Analysis of the loss of oncogenic B-Raf signaling on the phenotype of HT29 and Colo-205 cells (S2); Effects of B-RafV600E knockdown on Colo-205 cells (S3); Additional information on the transcriptome analysis of HT29 and Colo-205 spheroids, including further validation at the protein level (S4); Additional data supporting the (inverse) relationship between B-RafV600E signaling and the expression of Cdx-2, KIAA1199 and Claudins in HT29 and Colo-205 cells (S5); Additional data addressing the effects of B-RafV600E signaling on transcripts associated with invasion and stemness, on xenograft growth and tight junction proteins (S6); Supplementary data showing the single-channel images corresponding to Fig. 2C and 3D, respectively (S7); Inhibition of B-RafV600E modulates transcripts associated with intestinal differentiation (S8).

(S1) Supplemental Figure S1 shows the flow cytometry based analysis of B16 cells transformed with a lentiviral vector with Luc-GFP-neo (S2-S7) Supplemental Figures S2-S7 show complete western blot images (S8) Supplemental Figure S8 shows the impact of IFN gamma on melanoma cells with respect to gene expression, OCR and ROS production (S9) Supplemental Figure S9 shows the effect of prolonging combination therapy regimen in melanoma bearing mice (S10) Supplemental Figure S10 shows the combined effects of IFN-γ and miR-146a inhibition on melanoma cells in vitro (S11) Supplemental Figure S11 shows the proposed mechanism of action.

10060 Background: Preclinical data suggest that melanoma angiogenesis promotes resistance to MAPK-pathway (MAPKi) and immune checkpoint inhibitors (ICIs). However, phase II clinical trials of anti-angiogenic therapy in melanoma were disappointing. We previously identified a pathogenic germline variant Q472H in the kinase insert domain receptor [KDR Q472H; vascular endothelial growth factor receptor-2 (VEGFR-2)] in 35% of primary melanoma patients. We hypothesize that KDR Q472H promotes resistance to MAPKi or ICIs, and that combined MAPKi or ICI and VEGF pathway inhibition may improve outcomes in patients harboring the variant. Methods: Metastatic melanoma (MM) patient clinical data and biospecimens enrolled in the NYU Langone Medical Center Melanoma program were studied. KDR status was determined by TaqMan assays. Tumor microvessel density (MVD) was assessed by CD34 immunohistochemistry. The impact of KDR Q472H on the tumor microenvironment was determined by RNA-seq and Nanostring. Synergy between BRAF (dabrafenib) and VEGFR-2 (lenvatinib) inhibitors in KDR-genotyped MM cell lines was assessed using cell proliferation assays and the Chou-Talalay method. Synergy between ICIs and anti-VEGFR-2 was evaluated in vivo using a B16 melanoma model. Results: We studied 221 MM patients (38% KDR Q472H variants). KDR Q472H variant was significantly associated with higher tumor MVD (P = 0.002). Among the MAPKi-treated patients, KDR Q472H homozygotes had shorter median progression-free survival (PFS, 3.3 vs 9.7 months, P = 0.009) than KDR wild type (WT). In patients treated with anti-PD-1-based therapies, response rates were lower in KDR Q472H variant patients compared to WT (P = 0.012), with shorter median PFS (8.4 months vs not reached, P = 0.0443). Transcriptomic analyses identified an immunosuppressive phenotype in KDR Q472H tumors, with reduced expression of genes associated with chemotaxis, inflammation, T cell activity, and antigen presentation. Consistent with this finding, VEGFR-2 blockade in a KDR Q472H B16 mouse melanoma model augmented the anti-melanoma immune response. KDR Q472H cell lines displayed synergistic cytotoxicity with dabrafenib and lenvatinib, compared to KDR WT cells. Conclusions: Our data demonstrate that melanoma patients with pathogenic germline variant KDR Q472H may be more resistant to both ICIs and MAPKi. Anti-angiogenic therapy should be reconsidered within this specific subset of patients in prospective clinical trials.

The transcription factor SNAIL1 is a master regulator of epithelial-to-mesenchymal transition (EMT), a process entailing massive gene expression changes. To better understand SNAIL1-induced transcriptional reprogramming we performed time-resolved transcriptome analysis upon conditional SNAIL1 expression in colorectal cancer cells. Gene set variation analyses indicated that SNAIL1 strongly affected features related to cell cycle and Wnt/β-Catenin signalling. This correlated with upregulation of LEF1, a nuclear binding partner of β-Catenin. Likewise, transcriptomes of cell lines and colorectal cancers, including poor-prognosis mesenchymal tumours, exhibit positively correlated SNAI1 and LEF1 expression, and elevated LEF1 levels parallel increased patient mortality. To delineate the functional contribution of LEF1 to SNAIL1-induced EMT, we used the CRISPR/Cas9 system to knock-out LEF1 in colorectal cancer cells, and to engineer cells that express LEF1 mutants unable to interact with β-Catenin. Both complete LEF1-deficiency and prevention of the β-Catenin-LEF1 interaction impaired the ability of SNAIL1 to elicit expression of an alternative set of Wnt/β-catenin targets, and to promote cancer cell invasion. Conversely, overexpression of wildtype, but not of mutant LEF1, stimulated alternative Wnt/β-Catenin target gene expression, and caused cell-cycle arrest. Moreover, like SNAIL1, LEF1 retarded tumour growth in xenotransplantations. Thus, LEF1 phenocopies SNAIL1 with respect to several critical aspects of EMT. Indeed, comparative transcriptomics suggested that 35% of SNAIL1-induced transcriptional changes are attributable to LEF1. However, LEF1 did not autonomously induce EMT. Rather, LEF1 appears to be a strictly β-Catenin-dependent downstream effector of SNAIL1. Apparently, SNAIL1 employs β-Catenin-LEF1 complexes to redirect Wnt/β-Catenin pathway activity towards pro-invasive and anti-proliferative gene expression.

Rationale: The interaction of circulating cells within the vascular wall is a critical event in chronic inflammatory processes, such as atherosclerosis, but the control of the vascular inflammatory state is still largely unclear. Objective: This study was undertaken to characterize the function of the endothelial-enriched microRNA miR-100 during vascular inflammation and atherogenesis. Methods and Results: Based on a transcriptome analysis of endothelial cells after miR-100 overexpression, we identified miR-100 as a potent suppressor of endothelial adhesion molecule expression, resulting in attenuated leukocyte–endothelial interaction in vitro and in vivo as shown by flow cytometry and intravital imaging. Mechanistically, miR-100 directly repressed several components of mammalian target of rapamycin complex 1-signaling, including mammalian target of rapamycin and raptor, which resulted in a stimulation of endothelial autophagy and attenuated nuclear factor κB signaling in vitro and in vivo. In a low-density lipoprotein receptor–deficient atherosclerotic mouse model, pharmacological inhibition of miR-100 resulted in enhanced plaque lesion formation and a higher macrophage content of the plaque, whereas a systemic miR-100 replacement therapy had protective effects and attenuated atherogenesis, resulting in a decrease of plaque area by 45%. Finally, analysis of miR-100 expression in >70 samples obtained during carotid endarterectomy revealed that local miR-100 expression was inversely correlated with inflammatory cell content in patients. Conclusions: In summary, we describe an anti-inflammatory function of miR-100 in the vascular response to injury and inflammation and identify an important novel modulator of mammalian target of rapamycin signaling and autophagy in the vascular system. Our findings of miR-100 as a potential protective anti-athero-miR suggest that the therapeutic replacement of this microRNA could be a potential strategy for the treatment of chronic inflammatory diseases, such as atherosclerosis, in the future.

Abstract MicroRNAs (miR) are small noncoding RNAs that regulate gene expression, posttranscription, and manipulate immune responses in different types of cancers. In this study, we identify miR-146a as a negative regulator of immune activation, comparable to immune-checkpoint molecules. miR-146a levels were increased in melanoma microenvironmental tissue, and miR-146a−/− mice survived longer and developed less metastases in comparison with wild-type melanoma-bearing mice. T cells isolated from miR-146a−/− mice revealed higher expression levels of the miR-146a target gene Stat1 and the Stat1-regulated cytokine IFNγ. Neutralization of IFNγ in miR-146a−/− mice decreased survival and increased melanoma metastasis patterns to those of wild-type mice. In vitro, IFNγ reduced melanoma cell migration, cell-cycle activity, and basal metabolic rate. Conversely, IFNγ also increased PD-L1 levels on the melanoma cells, which may counterbalance some of the beneficial effects increasing immune escape in vivo. Combined treatment with a miR-146a antagomiR and anti–PD-1 resulted in improved survival over isotype control or anti–PD-1 treatment alone. In summary, these data show that miR-146a plays a central role within the STAT1/IFNγ axis in the melanoma microenvironment, affecting melanoma migration, proliferation, and mitochondrial fitness as well as PD-L1 levels. Additionally, combined inhibition of PD-1 and miR-146a could be a novel strategy to enhance antitumor immune response elicited by checkpoint therapy. Significance: These findings identify a microRNA–based mechanism by which melanoma cells escape the immune system, providing a new therapeutic strategy to improve the current management of patients with melanoma.

Autoantibodies have been associated with autoimmune diseases. However, studies have identified autoantibodies in healthy donors (HD) who do not develop autoimmune disorders. Here we provide evidence of a network of immunoglobulin G (IgG) autoantibodies targeting G protein-coupled receptors (GPCR) in HD compared to patients with systemic sclerosis, Alzheimer's disease, and ovarian cancer. Sex, age and pathological conditions affect autoantibody correlation and hierarchical clustering signatures, yet many of the correlations are shared across all groups, indicating alterations to homeostasis. Furthermore, we identify relationships between autoantibodies targeting structurally and functionally related molecules, such as vascular, neuronal or chemokine receptors. Finally, autoantibodies targeting the endothelin receptor type A (EDNRA) exhibit chemotactic activity, as demonstrated by neutrophil migration toward HD-IgG in an EDNRA-dependent manner and in the direction of IgG from EDNRA-immunized mice. Our data characterizing the in vivo signatures of anti-GPCR autoantibodies thus suggest that they are a physiological part of the immune system.

Despite being overexpressed in different tumor entities, RIO kinases are hardly characterized in mammalian cells. We investigated the role of these atypical kinases in different cancer cells. Using isogenic colon-, breast- and lung cancer cell lines, we demonstrate that knockdown of RIOK1, but not of RIOK2 or RIOK3, strongly impairs proliferation and invasiveness in conventional and 3D culture systems. Interestingly, these effects were mainly observed in RAS mutant cancer cells. In contrast, growth of RAS wildtype Caco-2 and Bcr-Abl-driven K562 cells is not affected by RIOK1 knockdown, suggesting a specific requirement for RIOK1 in the context of oncogenic RAS signaling. Furthermore, we show that RIOK1 activates NF-κB signaling and promotes cell cycle progression. Using proteomics, we identified the pro-invasive proteins Metadherin and Stathmin1 to be regulated by RIOK1. Additionally, we demonstrate that RIOK1 promotes lung colonization in vivo and that RIOK1 is overexpressed in different subtypes of human lung- and breast cancer. Altogether, our data suggest RIOK1 as a potential therapeutic target, especially in RAS-driven cancers.

Novel targeted and immunotherapeutic approaches have revolutionized the treatment of metastatic melanoma. A better understanding of the melanoma-microenvironment, in particular the interaction of cells with extracellular matrix molecules, may help to further improve these new therapeutic strategies.We observed that the extracellular matrix molecule biglycan (Bgn) was expressed in certain human melanoma cells and primary fibroblasts when evaluated by microarray-based gene expression analysis. Bgn expression in the melanoma tissues correlated with low overall-survival and low progression-free-survival in patients. To understand the functional role of Bgn we used gene-targeted mice lacking functional Bgn. Here we observed that melanoma growth, metastasis-formation and tumor-related death were reduced in Bgn-/- mice compared to Bgn+/+ mice. In vitro invasion of melanoma cells into organotypic-matrices derived from Bgn-/- fibroblasts was reduced compared to melanoma invasion into Bgn-proficient matrices. Tissue stiffness as determined by atomic-force-microscopy was reduced in Bgn-/- matrices. Isolation of melanoma cells and fibroblasts from the stiffer Bgn+/+ matrices revealed an increase in integrin-β1 expression compared to the Bgn-/- fibroblast matrices. Overexpression of integrin-β1 in B16-melanoma cells abolished the survival benefit seen in Bgn-/- mice. Consistent with the studies performed in mice, the abundance of Bgn-expression in human melanoma samples positively correlated with the expression of integrin-β1, which is in agreement with results from the organotypic invasion-assay and the in vivo mouse studies.This study describes a novel role for Bgn-related tissue stiffness in the melanoma-microenvironment via regulation of integrin-β1 expression by melanoma cells in both mice and humans.

The lipolysis-stimulated lipoprotein receptor (LSR) is a lipoprotein receptor, serves as host receptor for clostridial iota-like toxins and is involved in the formation of tricellular contacts. Of particular interest is the role of LSR in progression of various cancers. Here we aimed to study the tumor growth of LSR-deficient colon carcinoma-derived cell lines HCT116 and CaCo-2 in a mouse xenograft model. Whereas knockout of LSR had no effect on tumor growth of HCT116 cells, we observed that CaCo-2 LSR knockout tumors grew to a smaller size than their wild-type counterparts. Histological analysis revealed increased apoptotic and necrotic cell death in a tumor originating from LSR-deficient CaCo-2 cells. LSR-deficient CaCo-2 cells exhibited increased cell proliferation in vitro and an altered epithelial morphology with impaired targeting of tricellulin to tricellular contacts. In addition, loss of LSR reduced the transepithelial electrical resistance of CaCo-2 cell monolayers and increased permeability for small molecules. Moreover, LSR-deficient CaCo-2 cells formed larger cysts in 3D culture than their wild-type counterparts. Our study provides evidence that LSR affects epithelial morphology and barrier formation in CaCo-2 cells and examines for the first time the effects of LSR deficiency on the tumor growth properties of colon carcinoma-derived cell lines.