Constitutively active GSK3β as a means to bolster dendritic cell functionality in the face of tumour-mediated immune suppression

Targeting BCL9/BCL9L enhances antigen presentation by promoting conventional type 1 dendritic cell (cDC1) activation and tumor infiltration

Conventional type 1 dendritic cells (cDC1) are the essential antigen-presenting DC subset in antitumor immunity. Suppressing B-cell lymphoma 9 and B-cell lymphoma 9-like (BCL9/BCL9L) inhibits tumor growth and boosts immune responses against cancer. However, whether oncogenic BCL9/BCL9L impairs antigen presentation in tumors is still not completely understood. Here, we show that targeting BCL9/BCL9L enhanced antigen presentation by stimulating cDC1 activation and infiltration into tumor. Pharmacological inhibition of BCL9/BCL9L with a novel inhibitor hsBCL9z96 or Bcl9/Bcl9l knockout mice markedly delayed tumor growth and promoted antitumor CD8+ T cell responses. Mechanistically, targeting BCL9/BCL9L promoted antigen presentation in tumors. This is due to the increase of cDC1 activation and tumor infiltration by the XCL1-XCR1 axis. Importantly, using single-cell transcriptomics analysis, we found that Bcl9/Bcl9l deficient cDC1 were superior to wild-type (WT) cDC1 at activation and antigen presentation via NF-κB/IRF1 signaling. Together, we demonstrate that targeting BCL9/BCL9L plays a crucial role in cDC1-modulated antigen presentation of tumor-derived antigens, as well as CD8+ T cell activation and tumor infiltration. Targeting BCL9/BCL9L to regulate cDC1 function and directly orchestrate a positive feedback loop necessary for optimal antitumor immunity could serve as a potential strategy to counter immune suppression and enhance cancer immunotherapy.

Allogeneic NK cells induce the in vitro activation of monocyte-derived and conventional type-2 dendritic cells and trigger an inflammatory response under cancer-associated conditions

Natural killer (NK) cells are innate lymphocytes capable to recognize and kill virus-infected and cancer cells. In the past years, the use of allogeneic NK cells as anti-cancer therapy gained interest due to their ability to induce graft-versus-cancer responses without causing graft-versus-host disease and multiple protocols have been developed to produce high numbers of activated NK cells. While the ability of these cells to mediate tumor kill has been extensively studied, less is known about their capacity to influence the activity of other immune cells that may contribute to a concerted anti-tumor response in the tumor microenvironment (TME). In this study, we analyzed how an allogeneic off-the-shelf cord blood stem cell-derived NK-cell product influenced the activation of dendritic cells (DC). Crosstalk between NK cells and healthy donor monocyte-derived DC (MoDC) resulted in the release of IFNγ and TNF, MoDC activation, and the release of the T-cell-recruiting chemokines CXCL9 and CXCL10. Moreover, in the presence of prostaglandin-E2, NK cell/MoDC crosstalk antagonized the detrimental effect of IL-10 on MoDC maturation leading to higher expression of multiple (co-)stimulatory markers. The NK cells also induced activation of conventional DC2 (cDC2) and CD8+ T cells, and the release of TNF, GM-CSF, and CXCL9/10 in peripheral blood mononuclear cells of patients with metastatic colorectal cancer. The activated phenotype of MoDC/cDC2 and the increased release of pro-inflammatory cytokines and T-cell-recruiting chemokines resulting from NK cell/DC crosstalk should contribute to a more inflamed TME and may thus enhance the efficacy of T-cell-based therapies.

At the Crossroads of Molecular Biology and Immunology: Molecular Pathways for Immunological Targeting of Head and Neck Squamous Cell Carcinoma

Background: Recent advances in immunotherapy for head and neck squamous cell carcinoma (HNSCC) have led to implementation of anti-programmed death receptor 1 (PD-1) immunotherapy to standard of care for recurrent/metastatic HNSCC. However, the majority of tumors do not respond to these therapies, indicating that these tumors are not immunogenic or other immunosuppressive mechanisms might be at play. Aim: Given their role in carcinogenesis as well as in immune modulation, we discuss the relation between the STAT3, PI3K/AKT/mTOR and Wnt signaling pathways to identify potential targets to empower the immune response against HNSCC. Results: We focused on three pathways. First, STAT3 is often overactivated in HNSCC and induces the secretion of immunosuppressive cytokines, thereby promoting recruitment of immune suppressive regulatory T cells and myeloid-derived suppressor cells to the tumor microenvironment (TME) while hampering the development of dendritic cells. Second, PI3K/AKT/mTOR mutational activation results in increased tumor proliferation but could also be important in HNSCC immune evasion due to the downregulation of components in the antigen-processing machinery. Third, canonical Wnt signaling is overactivated in >20% of HNSCC and could be an interesting pleotropic target since it is related to increased tumor cell proliferation and the development of an immunosuppressive HNSCC TME. Conclusion: The molecular pathology of HNSCC is complex and heterogeneous, varying between sites and disease etiology (i.e., HPV). The in HNSCC widely affected signaling pathways STAT3, PI3K/AKT/mTOR and Wnt are implicated in some of the very mechanisms underlying immune evasion of HNSCC, thereby representing promising targets to possibly facilitate immunotherapy response.

Micro-environmental cross-talk in an organotypic human melanoma-in-skin model directs M2-like monocyte differentiation via IL-10

Preclinical assessment of novel therapies to fight cancer requires models that reflect the human physiology and immune response. Here, we established an in vitro three-dimensional (3D) reconstructed organotypic human melanoma-in-skin (Mel-RhS) model to investigate cellular and molecular features of tumor formation over a period of 6 weeks. Tumor nests developed over time at the epidermal-dermal junction and spread towards the dermis, in places disrupting the basement membrane. This coincided with secretion of matrix metalloproteinase 9 (MMP-9) by melanoma cells. These features resemble the initial stages of invasive melanoma. Interestingly, while the SK-MEL-28 cell line did not secrete detectable levels of interleukin-10 (IL-10) in traditional two-dimensional monolayers, it did express IL-10 in the 3D Mel-RhS, as did the surrounding keratinocytes and fibroblasts. This cellular cross-talk-induced secretion of IL-10 in the Mel-RhS indicated the generation of an immune suppressive microenvironment. Culture supernatants from Mel-RhS interfered with monocyte-to-dendritic-cell differentiation, leading to the development of M2-like macrophages, which was in part prevented by antibody-mediated IL-10 blockade. Indeed, high-dimensional single-cell analysis revealed a shift within the monocyte population away from a CD163+PD-L1+ M2-like phenotype upon IL-10 blockade. Thus, the 3D configuration of the Mel-RhS model revealed a role for IL-10 in immune escape through misdirected myeloid differentiation, which would have been missed in classical monolayer cultures.

Tumor Microenvironment: Implications in Melanoma Resistance to Targeted Therapy and Immunotherapy

Simple Summary

The response to pharmacological treatments is deeply influenced by the tight interactions between the tumor cells and the microenvironment. In this review we describe, for melanoma, the most important mechanisms of resistance to targeted therapy and immunotherapy mediated by the components of the microenvironment. In addition, we briefly describe the most recent therapeutic advances for this pathology. The knowledge of molecular mechanisms, which are underlying of drug resistance, is fundamental for the development of new therapeutic approaches for the treatment of melanoma patients.

Abstract

Antitumor therapies have made great strides in recent decades. Chemotherapy, aggressive and unable to discriminate cancer from healthy cells, has given way to personalized treatments that, recognizing and blocking specific molecular targets, have paved the way for targeted and effective therapies. Melanoma was one of the first tumor types to benefit from this new care frontier by introducing specific inhibitors for v-Raf murine sarcoma viral oncogene homolog B (BRAF), mitogen-activated protein kinase kinase (MEK), v-kit Hardy–Zuckerman 4 feline sarcoma viral oncogene homolog (KIT), and, recently, immunotherapy. However, despite the progress made in the melanoma treatment, primary and/or acquired drug resistance remains an unresolved problem. The molecular dynamics that promote this phenomenon are very complex but several studies have shown that the tumor microenvironment (TME) plays, certainly, a key role. In this review, we will describe the new melanoma treatment approaches and we will analyze the mechanisms by which TME promotes resistance to targeted therapy and immunotherapy.

Adenocarcinoma of the Uterine Cervix Shows Impaired Recruitment of cDC1 and CD8+ T Cells and Elevated β-Catenin Activation Compared with Squamous Cell Carcinoma

PURPOSE

Adenocarcinoma of the uterine cervix is the second most common type of cervical cancer after squamous cell carcinoma (SCC). Although both subtypes are treated similarly, patients with adenocarcinoma have a worse prognosis. In this study, immunologic features of the tumor microenvironment in these two subsets were pursued with potential therapeutic implications.

EXPERIMENTAL DESIGN

The immune microenvironment of primary tumors and nonmetastatic tumor-draining lymph nodes (TDLN) was compared between patients with cervical adenocarcinoma (n = 16) and SCC (n = 20) by polychromatic flow cytometry and by transcriptional profiling of the primary tumors (n = 299) using publicly available data from The Cancer Genome Atlas (TCGA).

RESULTS

Flow cytometric analyses revealed intact T-cell differentiation in TDLNs, but hampered effector T-cell trafficking to the primary tumors in adenocarcinoma, as compared with SCC. TCGA analysis demonstrated higher expression of chemokines involved in effector T-cell homing (CXCL9/10/11) in SCC primary tumors as compared with adenocarcinoma primary tumors, which was highly correlated to a transcriptional signature for type I conventional dendritic cells (cDC1). This was consistent with elevated frequencies of CD141/BDCA3⁺cDC1 in primary tumor SCC samples relative to adenocarcinoma and correspondingly elevated levels of CXCL9 and CXCL10 in 24-hour ex vivo cultures. Hampered cDC1 recruitment in adenocarcinoma was in turn related to lower transcript levels of cDC1-recruiting chemokines and an elevated β-catenin activation score and was associated with poor overall survival.

CONCLUSIONS

Our data have identified an opportunity for the investigation of potentially novel therapeutic interventions in adenocarcinoma of the cervix, that is, β-catenin inhibition and cDC1 mobilization.

Wnt Signaling Cascade in Dendritic Cells and Regulation of Anti-tumor Immunity

Dendritic cells (DCs) control the strength and quality of antigen-specific adaptive immune responses. This is critical for launching a robust immunity against invading pathogens while maintaining a state of tolerance to self-antigens. However, this also represents a fundamental barrier to anti-tumor immune responses and cancer immunotherapy. DCs in the tumor microenvironment (TME) play a key role in this process. The factors in the TME and signaling networks that program DCs to a regulatory state are not fully understood. Recent advances point to novel mechanisms by which the canonical Wnt signaling cascade in DCs regulates immune suppression, and the same pathway in tumors is associated with the evasion of anti-tumor immunity. Here, we review these recent advances in the context of the pleiotropic effects of the Wnts in shaping anti-tumor immune responses by modulating DC functions. In addition, we will discuss how Wnt/β-catenin pathway in DCs can be targeted for successful cancer immunotherapy.