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In this issue honoring the contributions of Greg Lemke, the Earp and Graham lab teams discuss several threads in the discovery, action, signaling, and translational/clinical potential of MERTK, originally called c-mer, a member of the TYRO3, AXL, and MERTK (TAM) family of receptor tyrosine kinases. The 30-year history of the TAM RTK family began slowly as all three members were orphan RTKs without known ligands and/or functions when discovered by three distinct alternate molecular cloning strategies in the pre-genome sequencing era. The pace of understanding their physiologic and pathophysiologic roles has accelerated over the last decade. The activation of ligands bridging externalized phosphatidylserine (PtdSer) has placed these RTKs in a myriad of processes including neurodevelopment, cancer, and autoimmunity. The field is ripe for further advancement and this article hopefully sets the stage for further understanding and therapeutic intervention. Our review will focus on progress made through the collaborations of the Earp and Graham labs over the past 30 years.
Assuntos
Neoplasias , c-Mer Tirosina Quinase , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , c-Mer Tirosina Quinase/metabolismo , c-Mer Tirosina Quinase/antagonistas & inibidores , c-Mer Tirosina Quinase/genética , Inibidores de Proteínas Quinases/uso terapêutico , Inibidores de Proteínas Quinases/farmacologia , Animais , Terapia de Alvo Molecular , Transdução de Sinais/efeitos dos fármacos , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , Receptores Proteína Tirosina Quinases/metabolismo , Receptores Proteína Tirosina Quinases/antagonistas & inibidoresRESUMO
Checkpoint inhibitors, specifically anti-PD-1, have shown success in treating metastatic melanoma; however, some patients develop resistance. Dendritic cells (DCs) play a key role in initiating an immune response but in certain circumstances they become ineffective. We investigated the role of MerTK, a receptor tyrosine kinase responsible for myeloid cell clearance of dead cells, in the regulation of DC function and metabolism in the tumor microenvironment. Tumors resistant to anti-PD-1 exhibited increased levels of MerTK+ DCs. Treating wild-type DCs with apoptotic dead melanoma cells in vitro resulted in increased MerTK expression, elevated mitochondrial respiration and fatty acid oxidation, and reduced T-cell stimulatory capacity, all characteristics of dysfunctional DCs. In contrast, dead cells had only limited effect on the metabolism of MerTK-deficient DCs, which instead maintained an antigen presenting, stimulatory phenotype. The efficacy of anti-PD-1 to slow tumor progression and induce specific T-cell infiltration was markedly increased in mice with selective ablation of MerTK in the DC compartment, suggesting the possibility of therapeutically targeting MerTK to modulate DC metabolism and function and enhance anti-PD-1 therapy.
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Conventional dendritic cells (DCs) are essential mediators of antitumor immunity. As a result, cancers have developed poorly understood mechanisms to render DCs dysfunctional within the tumor microenvironment (TME). After identification of CD63 as a specific surface marker, we demonstrate that mature regulatory DCs (mregDCs) migrate to tumor-draining lymph node tissues and suppress DC antigen cross-presentation in trans while promoting T helper 2 and regulatory T cell differentiation. Transcriptional and metabolic studies showed that mregDC functionality is dependent on the mevalonate biosynthetic pathway and its master transcription factor, SREBP2. We found that melanoma-derived lactate activates SREBP2 in tumor DCs and drives conventional DC transformation into mregDCs via homeostatic or tolerogenic maturation. DC-specific genetic silencing and pharmacologic inhibition of SREBP2 promoted antitumor CD8+ T cell activation and suppressed melanoma progression. CD63+ mregDCs were found to reside within the lymph nodes of several preclinical tumor models and in the sentinel lymph nodes of patients with melanoma. Collectively, this work suggests that a tumor lactate-stimulated SREBP2-dependent program promotes CD63+ mregDC development and function while serving as a promising therapeutic target for overcoming immune tolerance in the TME.
Assuntos
Células Dendríticas , Ácido Láctico , Melanoma , Transdução de Sinais , Proteína de Ligação a Elemento Regulador de Esterol 2 , Animais , Feminino , Humanos , Camundongos , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Progressão da Doença , Tolerância Imunológica/imunologia , Ácido Láctico/metabolismo , Melanoma/imunologia , Melanoma/patologia , Melanoma Experimental/imunologia , Melanoma Experimental/patologia , Camundongos Endogâmicos C57BL , Transdução de Sinais/imunologia , Proteína de Ligação a Elemento Regulador de Esterol 2/imunologia , Microambiente Tumoral/imunologiaRESUMO
Dendritic cells (cDCs) are essential mediators of anti-tumor immunity. Cancers have developed mechanisms to render DCs dysfunctional within the tumor microenvironment. Utilizing CD63 as a unique surface marker, we demonstrate that mature regulatory DCs (mregDCs) suppress DC antigen cross-presentation while driving T H 2 and regulatory T cell differentiation within tumor-draining lymph node tissues. Transcriptional and metabolic studies show that mregDC functionality is dependent upon the mevalonate biosynthetic pathway and the master transcription factor, SREBP2. Melanoma-derived lactate activates DC SREBP2 in the tumor microenvironment (TME) and drives mregDC development from conventional DCs. DC-specific genetic silencing and pharmacologic inhibition of SREBP2 promotes anti-tumor CD8 + T cell activation and suppresses melanoma progression. CD63 + mregDCs reside within the sentinel lymph nodes of melanoma patients. Collectively, this work describes a tumor-driven SREBP2-dependent program that promotes CD63 + mregDC development and function while serving as a promising therapeutic target for overcoming immune tolerance in the TME. One Sentence Summary: The metabolic transcription factor, SREBF2, regulates the development and tolerogenic function of the mregDC population within the tumor microenvironment.
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The tumor-intrinsic NOD-, LRR- and pyrin domain-containing protein-3 (NLRP3) inflammasome-heat shock protein 70 (HSP70) signaling axis is triggered by CD8+ T cell cytotoxicity and contributes to the development of adaptive resistance to anti-programmed cell death protein 1 (PD-1) immunotherapy by recruiting granulocytic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) into the tumor microenvironment. Here, we demonstrate that the tumor NLRP3-HSP70 axis also drives the accumulation of PMN-MDSCs into distant lung tissues in a manner that depends on lung epithelial cell Toll-like receptor 4 (TLR4) signaling, establishing a premetastatic niche that supports disease hyperprogression in response to anti-PD-1 immunotherapy. Lung epithelial HSP70-TLR4 signaling induces the downstream Wnt5a-dependent release of granulocyte colony-stimulating factor (G-CSF) and C-X-C motif chemokine ligand 5 (CXCL5), thus promoting myeloid granulopoiesis and recruitment of PMN-MDSCs into pulmonary tissues. Treatment with anti-PD-1 immunotherapy enhanced the activation of this pathway through immunologic pressure and drove disease progression in the setting of Nlrp3 amplification. Genetic and pharmacologic inhibition of NLRP3 and HSP70 blocked PMN-MDSC accumulation in the lung in response to anti-PD-1 therapy and suppressed metastatic progression in preclinical models of melanoma and breast cancer. Elevated baseline concentrations of plasma HSP70 and evidence of NLRP3 signaling activity in tumor tissue specimens correlated with the development of disease hyperprogression and inferior survival in patients with stage IV melanoma undergoing anti-PD-1 immunotherapy. Together, this work describes a pathogenic mechanism underlying the phenomenon of disease hyperprogression in melanoma and offers candidate targets and markers capable of improving the management of patients with melanoma.
Assuntos
Melanoma , Receptor 4 Toll-Like , Humanos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Imunoterapia , Melanoma/patologia , Progressão da Doença , Microambiente TumoralRESUMO
The mechanisms underlying tumor immunosurveillance and their association with the immune-related adverse events (irAEs) associated with checkpoint inhibitor immunotherapies remain poorly understood. We describe a metastatic melanoma patient exhibiting multiple episodes of spontaneous disease regression followed by the development of several irAEs during the course of anti-programmed cell death protein 1 antibody immunotherapy. Whole-exome next-generation sequencing studies revealed this patient to harbor a pyrin inflammasome variant previously described to be associated with an atypical presentation of familial Mediterranean fever. This work highlights a potential role for inflammasomes in the regulation of tumor immunosurveillance and the pathogenesis of irAEs.
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Antineoplásicos Imunológicos , Melanoma , Segunda Neoplasia Primária , Antineoplásicos Imunológicos/uso terapêutico , Humanos , Imunoterapia/efeitos adversos , Melanoma/diagnóstico , Melanoma/tratamento farmacológico , Melanoma/genética , Segunda Neoplasia Primária/etiologia , PirinaRESUMO
The tumor-intrinsic NOD-like receptor family, pyrin-domain-containing-3 (NLRP3) inflammasome, plays an important role in regulating immunosuppressive myeloid cell populations in the tumor microenvironment (TME). While prior studies have described the activation of this inflammasome in driving pro-tumorigenic mechanisms, emerging data is now revealing the tumor NLRP3 inflammasome and the downstream release of heat shock protein-70 (HSP70) to regulate anti-tumor immunity and contribute to the development of adaptive resistance to anti-PD-1 immunotherapy. Genetic alterations that influence the activity of the NLRP3 signaling axis are likely to impact T cell-mediated tumor cell killing and may indicate which tumors rely on this pathway for immune escape. These studies suggest that the NLRP3 inflammasome and its secreted product, HSP70, represent promising pharmacologic targets for manipulating innate immune cell populations in the TME while enhancing responses to anti-PD-1 immunotherapy. Additional studies are needed to better understand tumor-specific regulatory mechanisms of NLRP3 to enable the development of tumor-selective pharmacologic strategies capable of augmenting responses to checkpoint inhibitor immunotherapy while minimizing unwanted off-target effects. The execution of upcoming clinical trials investigating this strategy to overcome anti-PD-1 resistance promises to provide novel insight into the role of this pathway in immuno-oncology.
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While immune checkpoint blockade is associated with prolonged responses in multiple cancers, most patients still do not benefit from this therapeutic strategy. The Wnt-ß-catenin pathway is associated with diminished T cell infiltration; however, activating mutations are rare, implicating a role for autocrine/paracrine Wnt ligand-driven signaling in immune evasion. In this study, we show that proximal mediators of the Wnt signaling pathway are associated with anti-PD-1 resistance, and pharmacologic inhibition of Wnt ligand signaling supports anti-PD-1 efficacy by reversing dendritic cell tolerization and the recruitment of granulocytic myeloid-derived suppressor cells in autochthonous tumor models. We further demonstrate that the inhibition of Wnt signaling promotes the development of a tumor microenvironment that is more conducive to favorable responses to checkpoint blockade in cancer patients. These findings support a rationale for Wnt ligand-focused treatment approaches in future immunotherapy clinical trials and suggest a strategy for selecting those tumors more responsive to Wnt inhibition.
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Imunoterapia/métodos , Ligantes , Proteína Wnt1/metabolismo , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Microambiente TumoralRESUMO
An in-depth understanding of immune escape mechanisms in cancer is likely to lead to innovative advances in immunotherapeutic strategies. However, much remains unknown regarding these mechanisms and how they impact immunotherapy resistance. Using several preclinical tumor models as well as clinical specimens, we identified a mechanism whereby CD8+ T cell activation in response to programmed cell death 1 (PD-1) blockade induced a programmed death ligand 1/NOD-, LRR-, and pyrin domain-containing protein 3 (PD-L1/NLRP3) inflammasome signaling cascade that ultimately led to the recruitment of granulocytic myeloid-derived suppressor cells (PMN-MDSCs) into tumor tissues, thereby dampening the resulting antitumor immune response. The genetic and pharmacologic inhibition of NLRP3 suppressed PMN-MDSC tumor infiltration and significantly augmented the efficacy of anti-PD-1 antibody immunotherapy. This pathway therefore represents a tumor-intrinsic mechanism of adaptive resistance to anti-PD-1 checkpoint inhibitor immunotherapy and is a promising target for future translational research.
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Antígeno B7-H1/imunologia , Inflamassomos/imunologia , Melanoma/terapia , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Animais , Antígeno B7-H1/antagonistas & inibidores , Linfócitos T CD8-Positivos/imunologia , Linhagem Celular Tumoral , Feminino , Humanos , Imunoterapia , Masculino , Melanoma/imunologia , Melanoma Experimental/imunologia , Melanoma Experimental/terapia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Imunológicos , Células Supressoras Mieloides/imunologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/antagonistas & inibidores , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Transdução de Sinais/imunologia , Pesquisa Translacional Biomédica , Evasão Tumoral/imunologia , Microambiente Tumoral/imunologiaRESUMO
Myeloid cell receptor tyrosine kinases TYRO3, AXL, and MERTK and their ligands, GAS6 and PROTEIN S, physiologically suppress innate immune responses, including in the tumor microenvironment. Here, we showed that myeloid-derived suppressor cells (MDSC) dramatically upregulated TYRO3, AXL, and MERTK and their ligands [monocytic MDSCs (M-MDSC)>20-fold, polymorphonuclear MDSCs (PMN-MDSC)>15-fold] in tumor-bearing mice. MDSCs from tumor-bearing Mertk-/-, Axl-/- , and Tyro3-/- mice exhibited diminished suppressive enzymatic capabilities, displayed deficits in T-cell suppression, and migrated poorly to tumor-draining lymph nodes. In coimplantation experiments using TYRO3-/-, AXL-/-, and MERTK-/- MDSCs, we showed the absence of these RTKs reversed the protumorigenic properties of MDSCs in vivo Consistent with these findings, in vivo pharmacologic TYRO3, AXL, and MERTK inhibition diminished MDSC suppressive capability, slowed tumor growth, increased CD8+ T-cell infiltration, and augmented anti-PD-1 checkpoint inhibitor immunotherapy. Mechanistically, MERTK regulated MDSC suppression and differentiation in part through regulation of STAT3 serine phosphorylation and nuclear localization. Analysis of metastatic melanoma patients demonstrated an enrichment of circulating MERTK+ and TYRO3+ M-MDSCs, PMN-MDSCs, and early-stage MDSCs (e-MDSC) relative to these MDSC populations in healthy controls. These studies demonstrated that TYRO3, AXL, and MERTK control MDSC functionality and serve as promising pharmacologic targets for regulating MDSC-mediated immune suppression in cancer patients.
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Antineoplásicos Imunológicos/farmacologia , Linfócitos T CD8-Positivos/imunologia , Melanoma/tratamento farmacológico , Células Supressoras Mieloides/metabolismo , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Proteínas Proto-Oncogênicas/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , c-Mer Tirosina Quinase/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Linhagem Celular Tumoral , Feminino , Voluntários Saudáveis , Humanos , Masculino , Melanoma/metabolismo , Melanoma/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Células Supressoras Mieloides/efeitos dos fármacos , Células Supressoras Mieloides/imunologia , Microambiente Tumoral , Adulto Jovem , Receptor Tirosina Quinase AxlRESUMO
Akt plays indispensable roles in cell proliferation, survival and metabolism. Mechanisms underlying posttranslational modification-mediated Akt activation have been extensively studied yet the Akt interactome is less understood. Here, we report that SAV1, a Hippo signaling component, inhibits Akt, a function independent of its role in Hippo signaling. Binding to a proline-tyrosine motif in the Akt-PH domain, SAV1 suppresses Akt activation by blocking Akt's movement to plasma membrane. We further identify cancer-associated SAV1 mutations with impaired ability to bind Akt, leading to Akt hyperactivation. We also determine that MERTK phosphorylates Akt1-Y26, releasing SAV1 binding and allowing Akt responsiveness to canonical PI-3K pathway activation. This work provides a mechanism underlying MERTK-mediated Akt activation and survival signaling in kidney cancer. Akt activation drives oncogenesis and therapeutic resistance; this mechanism of Akt regulation by MERTK/SAV1 provides yet another complexity in an extensively studied pathway, and may yield prognostic information and therapeutic targets.
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Proteínas de Ciclo Celular/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , c-Mer Tirosina Quinase/metabolismo , Animais , Carcinoma de Células Renais/metabolismo , Carcinoma de Células Renais/patologia , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Feminino , Células HEK293 , Células HeLa , Xenoenxertos , Via de Sinalização Hippo , Humanos , Neoplasias Renais/metabolismo , Neoplasias Renais/patologia , Camundongos , Camundongos Nus , Mutação , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de SinaisRESUMO
Although anti-PD-1 therapy has improved clinical outcomes for select patients with advanced cancer, many patients exhibit either primary or adaptive resistance to checkpoint inhibitor immunotherapy. The role of the tumor stroma in the development of these mechanisms of resistance to checkpoint inhibitors remains unclear. We demonstrated that pharmacologic inhibition of the TGFß signaling pathway synergistically enhanced the efficacy of anti-CTLA-4 immunotherapy but failed to augment anti-PD-1/PD-L1 responses in an autochthonous model of BRAFV600E melanoma. Additional mechanistic studies revealed that TGFß pathway inhibition promoted the proliferative expansion of stromal fibroblasts, thereby facilitating MMP-9-dependent cleavage of PD-L1 surface expression, leading to anti-PD-1 resistance in this model. Further work demonstrated that melanomas escaping anti-PD-1 therapy exhibited a mesenchymal phenotype associated with enhanced TGFß signaling activity. Delayed TGFß inhibitor therapy, following anti-PD-1 escape, better served to control further disease progression and was superior to a continuous combination of anti-PD-1 and TGFß inhibition. This work illustrates that formulating immunotherapy combination regimens to enhance the efficacy of checkpoint blockade requires an in-depth understanding of the impact of these agents on the tumor microenvironment. These data indicated that stromal fibroblast MMP-9 may desensitize tumors to anti-PD-1 and suggests that TGFß inhibition may generate greater immunologic efficacy when administered following the development of acquired anti-PD-1 resistance.See related Spotlight on p. 1444.
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Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Metaloproteinase 9 da Matriz/metabolismo , Melanoma/tratamento farmacológico , Melanoma/imunologia , Fator de Crescimento Transformador beta/antagonistas & inibidores , Animais , Antígeno B7-H1/imunologia , Antígeno B7-H1/metabolismo , Antígeno CTLA-4/antagonistas & inibidores , Antígeno CTLA-4/imunologia , Resistencia a Medicamentos Antineoplásicos/fisiologia , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/patologia , Imunoterapia/métodos , Masculino , Metaloproteinase 9 da Matriz/imunologia , Melanoma/metabolismo , Melanoma/patologia , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Proto-Oncogênicas B-raf/genética , Pirazóis/farmacologia , Quinolinas/farmacologia , Fator de Crescimento Transformador beta/metabolismo , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Tyro3, Axl, Mer (TAM) receptor tyrosine kinases reduce inflammatory, innate immune responses. We demonstrate that tumor-secreted protein S (Pros1), a Mer/Tyro3 ligand, decreased macrophage M1 cytokine expression in vitro and in vivo. In contrast, tumor cells with CRISPR-based deletion of Pros1 failed to inhibit M1 polarization. Tumor cell-associated Pros1 action was abrogated in macrophages from Mer- and Tyro3- but not Axl-KO mice. In addition, several other murine and human tumor cell lines suppressed macrophage M1 cytokine expression induced by IFN-γ and LPS. Investigation of the suppressive pathway demonstrated a role for PTP1b complexing with Mer. Substantiating the role of PTP1b, M1 cytokine suppression was also lost in macrophages from PTP1b-KO mice. Mice bearing Pros1-deficient tumors showed increased innate and adaptive immune infiltration, as well as increased median survival. TAM activation can also inhibit TLR-mediated M1 polarization. Treatment with resiquimod, a TLR7/8 agonist, did not improve survival in mice bearing Pros1-secreting tumors but doubled survival for Pros1-deleted tumors. The tumor-derived Pros1 immune suppressive system, like PD-L1, was cytokine responsive, with IFN-γ inducing Pros1 transcription and secretion. Inhibition of Pros1/TAM interaction represents a potential novel strategy to block tumor-derived immune suppression.
Assuntos
Proteínas de Transporte/imunologia , Macrófagos/imunologia , Neoplasias Experimentais/imunologia , Animais , Antígeno B7-H1/genética , Antígeno B7-H1/imunologia , Proteínas de Ligação ao Cálcio , Proteínas de Transporte/genética , Citocinas/genética , Citocinas/imunologia , Humanos , Imidazóis/farmacologia , Macrófagos/patologia , Glicoproteínas de Membrana/agonistas , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Camundongos , Camundongos Knockout , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , Receptor 7 Toll-Like/agonistas , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/imunologia , Receptor 8 Toll-Like/agonistas , Receptor 8 Toll-Like/genética , Receptor 8 Toll-Like/imunologiaRESUMO
Lung cancer is the leading cause of cancer-related deaths worldwide, and lung squamous carcinomas (LUSC) represent about 30% of cases. Molecular aberrations in lung adenocarcinomas have allowed for effective targeted treatments, but corresponding therapeutic advances in LUSC have not materialized. However, immune checkpoint inhibitors in sub-populations of LUSC patients have led to exciting responses. Using computational analyses of The Cancer Genome Atlas, we identified a subset of LUSC tumors characterized by dense infiltration of inflammatory monocytes (IMs) and poor survival. With novel, immunocompetent metastasis models, we demonstrated that tumor cell derived CCL2-mediated recruitment of IMs is necessary and sufficient for LUSC metastasis. Pharmacologic inhibition of IM recruitment had substantial anti-metastatic effects. Notably, we show that IMs highly express Factor XIIIA, which promotes fibrin cross-linking to create a scaffold for LUSC cell invasion and metastases. Consistently, human LUSC samples containing extensive cross-linked fibrin in the microenvironment correlated with poor survival.
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Carcinoma de Células Escamosas/imunologia , Fator XIIIa/imunologia , Fibrina/química , Neoplasias Pulmonares/imunologia , Monócitos/imunologia , Animais , Biomarcadores Tumorais/química , Biomarcadores Tumorais/imunologia , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Quimiocina CCL2/genética , Quimiocina CCL2/imunologia , Fator XIIIa/genética , Feminino , Fibrina/imunologia , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Masculino , Camundongos , Camundongos Endogâmicos DBA , Invasividade NeoplásicaRESUMO
Despite recent advances, many cancers remain refractory to available immunotherapeutic strategies. Emerging evidence indicates that the tolerization of local dendritic cells (DCs) within the tumor microenvironment promotes immune evasion. Here, we have described a mechanism by which melanomas establish a site of immune privilege via a paracrine Wnt5a-ß-catenin-peroxisome proliferator-activated receptor-γ (PPAR-γ) signaling pathway that drives fatty acid oxidation (FAO) in DCs by upregulating the expression of the carnitine palmitoyltransferase-1A (CPT1A) fatty acid transporter. This FAO shift increased the protoporphyrin IX prosthetic group of indoleamine 2,3-dioxgenase-1 (IDO) while suppressing interleukin(IL)-6 and IL-12 cytokine expression, culminating in enhanced IDO activity and the generation of regulatory T cells. We demonstrated that blockade of this pathway augmented anti-melanoma immunity, enhanced the activity of anti-PD-1 antibody immunotherapy, and suppressed disease progression in a transgenic melanoma model. This work implicates a role for tumor-mediated metabolic reprogramming of local DCs in immune evasion and immunotherapy resistance.
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Células Dendríticas/metabolismo , Melanoma/imunologia , Proteína Wnt-5a/metabolismo , beta Catenina/metabolismo , Animais , Linhagem Celular , Células Dendríticas/imunologia , Ensaio de Imunoadsorção Enzimática , Ácidos Graxos/metabolismo , Feminino , Citometria de Fluxo , Immunoblotting , Masculino , Melanoma/metabolismo , Camundongos , Camundongos Transgênicos , PPAR gama/metabolismo , Comunicação Parácrina/fisiologia , Reação em Cadeia da Polimerase , Transdução de Sinais/fisiologiaRESUMO
The ß-catenin signaling pathway has been demonstrated to promote the development of a tolerogenic dendritic cell (DC) population capable of driving regulatory T-cell (Treg) differentiation. Further studies have implicated tolerogenic DCs in promoting carcinogenesis in preclinical models. The molecular mechanisms underlying the establishment of immune tolerance by this DC population are poorly understood, and the methods by which developing cancers can co-opt this pathway to subvert immune surveillance are currently unknown. This work demonstrates that melanoma-derived Wnt5a ligand upregulates the durable expression and activity of the indoleamine 2,3-dioxygenase-1 (IDO) enzyme by local DCs in a manner that depends upon the ß-catenin signaling pathway. These data indicate that Wnt5a-conditioned DCs promote the differentiation of Tregs in an IDO-dependent manner, and that this process serves to suppress melanoma immune surveillance. We further show that the genetic silencing of the PORCN membrane-bound O-acyl transferase, which is necessary for melanoma Wnt ligand secretion, enhances antitumor T-cell immunity, and that the pharmacologic inhibition of this enzyme synergistically suppresses melanoma progression when combined with anti-CTLA-4 antibody therapy. Finally, our data suggest that ß-catenin signaling activity, based on a target gene expression profile that includes IDO in human sentinel lymph node-derived DCs, is associated with melanoma disease burden and diminished progression-free survival. This work implicates the Wnt-ß-catenin signaling pathway as a novel therapeutic target in the melanoma immune microenvironment and demonstrates the potential impact of manipulating DC function as a strategy for optimizing tumor immunotherapy.
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Células Dendríticas/enzimologia , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Melanoma/metabolismo , Proteínas Proto-Oncogênicas/fisiologia , Proteínas Wnt/fisiologia , Aciltransferases , Animais , Anticorpos Monoclonais/uso terapêutico , Benzenoacetamidas/farmacologia , Benzenoacetamidas/uso terapêutico , Antígeno CTLA-4/antagonistas & inibidores , Comunicação Celular/imunologia , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Progressão da Doença , Humanos , Tolerância Imunológica/imunologia , Imunoterapia/métodos , Linfonodos/imunologia , Melanoma/imunologia , Melanoma/patologia , Melanoma/terapia , Proteínas de Membrana/antagonistas & inibidores , Camundongos Endogâmicos , Camundongos Transgênicos , Terapia de Alvo Molecular/métodos , Transplante de Neoplasias , Piridinas/farmacologia , Piridinas/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Linfócitos T Reguladores/imunologia , Proteína Wnt-5a , beta Catenina/metabolismoRESUMO
Although prolonged genetic pressure has been conjectured to be necessary for the eventual development of tumor immune evasion mechanisms, recent work is demonstrating that early genetic mutations are capable of moonlighting as both intrinsic and extrinsic modulators of the tumor immune microenvironment. The indoleamine 2,3-dioxygenase-1 (IDO) immunoregulatory enzyme is emerging as a key player in tumor-mediated immune tolerance. While loss of the tumor suppressor, BIN-1, and the over-expression of cyclooxygenase-2 have been implicated in intrinsic regulation of IDO, recent findings have demonstrated the loss of TßRIII and the upregulation of Wnt5a by developing cancers to play a role in the extrinsic control of IDO activity by local dendritic cell populations residing within tumor and tumor-draining lymph node tissues. Together, these genetic changes are capable of modulating paracrine signaling pathways in the early stages of carcinogenesis to establish a site of immune privilege by promoting the differentiation and activation of local regulatory T cells. Additional investigation of these immune evasion pathways promises to provide opportunities for the development of novel strategies to synergistically enhance the efficacy of the evolving class of T cell-targeted "checkpoint" inhibitors.
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The bone morphogenetic protein (BMP) signaling pathways have important roles in embryonic development and cellular homeostasis, with aberrant BMP signaling resulting in a broad spectrum of human disease. We report that BMPs unexpectedly signal through the canonical transforming growth factor ß (TGF-ß)-responsive Smad2 and Smad3. BMP-induced Smad2/3 signaling occurs preferentially in embryonic cells and transformed cells. BMPs signal to Smad2/3 by stimulating complex formation between the BMP-binding TGF-ß superfamily receptors, activin receptor-like kinase (ALK)3/6, and the Smad2/3 phosphorylating receptors ALK5/7. BMP signaling through Smad2 mediates, in part, dorsoventral axis patterning in zebrafish embryos, whereas BMP signaling through Smad3 facilitates cancer cell invasion. Consistent with increased BMP-mediated Smad2/3 signaling during cancer progression, Smad1/5 and Smad 2/3 signaling converge in human cancer specimens. Thus, the signaling mechanisms used by BMPs and TGF-ß superfamily receptors are broader than previously appreciated.
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Proteínas Morfogenéticas Ósseas/metabolismo , Transdução de Sinais , Proteína Smad2/metabolismo , Proteína Smad3/metabolismo , Animais , Humanos , FosforilaçãoRESUMO
Cancers subvert the host immune system to facilitate disease progression. These evolved immunosuppressive mechanisms are also implicated in circumventing immunotherapeutic strategies. Emerging data indicate that local tumor-associated DC populations exhibit tolerogenic features by promoting Treg development; however, the mechanisms by which tumors manipulate DC and Treg function in the tumor microenvironment remain unclear. Type III TGF-ß receptor (TGFBR3) and its shed extracellular domain (sTGFBR3) regulate TGF-ß signaling and maintain epithelial homeostasis, with loss of TGFBR3 expression promoting progression early in breast cancer development. Using murine models of breast cancer and melanoma, we elucidated a tumor immunoevasion mechanism whereby loss of tumor-expressed TGFBR3/sTGFBR3 enhanced TGF-ß signaling within locoregional DC populations and upregulated both the immunoregulatory enzyme indoleamine 2,3-dioxygenase (IDO) in plasmacytoid DCs and the CCL22 chemokine in myeloid DCs. Alterations in these DC populations mediated Treg infiltration and the suppression of antitumor immunity. Our findings provide mechanistic support for using TGF-ß inhibitors to enhance the efficacy of tumor immunotherapy, indicate that sTGFBR3 levels could serve as a predictive immunotherapy biomarker, and expand the mechanisms by which TGFBR3 suppresses cancer progression to include effects on the tumor immune microenvironment.
Assuntos
Neoplasias Mamárias Experimentais/imunologia , Melanoma Experimental/imunologia , Proteoglicanas/genética , Receptores de Fatores de Crescimento Transformadores beta/genética , Evasão Tumoral , Microambiente Tumoral/imunologia , Animais , Linhagem Celular Tumoral , Quimiocina CCL22/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Regulação para Baixo , Feminino , Humanos , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transplante de Neoplasias , Proteoglicanas/metabolismo , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
The type III TGF-ß receptor (TßRIII or betagylcan) is a TGF-ß superfamily coreceptor with emerging roles in regulating TGF-ß superfamily signaling and cancer progression. Alterations in TGF-ß superfamily signaling are common in colon cancer; however, the role of TßRIII has not been examined. Although TßRIII expression is frequently lost at the message and protein level in human cancers and suppresses cancer progression in these contexts, here we demonstrate that, in colon cancer, TßRIII messenger RNA expression is not significantly altered and TßRIII expression is more frequently increased at the protein level, suggesting a distinct role for TßRIII in colon cancer. Increasing TßRIII expression in colon cancer model systems enhanced ligand-mediated phosphorylation of p38 and the Smad proteins, while switching TGF-ß and BMP-2 from inhibitors to stimulators of colon cancer cell proliferation, inhibiting ligand-induced p21 and p27 expression. In addition, increasing TßRIII expression increased ligand-stimulated anchorage-independent growth, a resistance to ligand- and chemotherapy-induced apoptosis, cell migration and modestly increased tumorigenicity in vivo. In a reciprocal manner, silencing endogenous TßRIII expression decreased colon cancer cell migration. These data support a model whereby TßRIII mediates TGF-ß superfamily ligand-induced colon cancer progression and support a context-dependent role for TßRIII in regulating cancer progression.