Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is known for specifically killing cancer cells, whereas in resistant cancers, TRAIL/TRAIL-R can promote metastasis via Rac1 and ...PI3K. It remains unknown, however, whether and to what extent TRAIL/TRAIL-R signaling in cancer cells can affect the immune microenvironment. Here we show that TRAIL-triggered cytokine secretion from TRAIL-resistant cancer cells is FADD dependent and identify the TRAIL-induced secretome to drive monocyte polarization to myeloid-derived suppressor cells (MDSCs) and M2-like macrophages. TRAIL-R suppression in tumor cells impaired CCL2 production and diminished both lung MDSC presence and tumor growth. In accordance, the receptor of CCL2, CCR2, is required to facilitate increased MDSC presence and tumor growth. Finally, TRAIL and CCL2 are co-regulated with MDSC/M2 markers in lung adenocarcinoma patients. Collectively, endogenous TRAIL/TRAIL-R-mediated CCL2 secretion promotes accumulation of tumor-supportive immune cells in the cancer microenvironment, thereby revealing a tumor-supportive immune-modulatory role of the TRAIL/TRAIL-R system in cancer biology.
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•TRAIL induces a cytokine cancer secretome in a FADD- and caspase-8-dependent manner•FADD promotes tumor growth along with accumulation of M2-like immune cells in vivo•The TRAIL-induced secretome recruits M2-like immune cells to tumors via CCR2•TRAIL/CCL2 correlate with a tumor-supportive immune profile in lung cancer patients
Hartwig et al. show that endogenous TRAIL signaling in cancer cells induces a FADD-dependent secretome that promotes the accumulation of M2-like immune cells and tumor growth via host CCR2.
Ubiquitination and deubiquitination are crucial for assembly and disassembly of signaling complexes. LUBAC-generated linear (M1) ubiquitin is important for signaling via various immune receptors. We ...show here that the deubiquitinases CYLD and A20, but not OTULIN, are recruited to the TNFR1- and NOD2-associated signaling complexes (TNF-RSC and NOD2-SC), at which they cooperate to limit gene activation. Whereas CYLD recruitment depends on its interaction with LUBAC, but not on LUBAC’s M1-chain-forming capacity, A20 recruitment requires this activity. Intriguingly, CYLD and A20 exert opposing effects on M1 chain stability in the TNF-RSC and NOD2-SC. While CYLD cleaves M1 chains, and thereby sensitizes cells to TNF-induced death, A20 binding to them prevents their removal and, consequently, inhibits cell death. Thus, CYLD and A20 cooperatively restrict gene activation and regulate cell death via their respective activities on M1 chains. Hence, the interplay between LUBAC, M1-ubiquitin, CYLD, and A20 is central for physiological signaling through innate immune receptors.
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•LUBAC directly recruits CYLD to the TNFR1 complex where it antagonizes M1 linkages•M1-ubiquitin chains recruit A20, which, in turn, protects them from degradation•CYLD and A20 inhibit gene activation but oppose each other in regulating cell death•OTULIN controls LUBAC activity prior to stimulation but not in signaling complexes
Linear ubiquitin is an important regulator of immune signaling. Draber et al. show that the deubiquitinase CYLD antagonizes linear ubiquitin in signaling complexes. A20 is recruited to complexes via linear ubiquitin and, in turn, protects linear ubiquitin from cleavage. A20 and CYLD cooperatively inhibit gene activation but oppose each other to regulate TNF-induced cell death via their respective activities on linear ubiquitin.
The linear ubiquitin chain assembly complex (LUBAC) is the only known E3 ubiquitin ligase which catalyses the generation of linear ubiquitin linkages de novo. LUBAC is a crucial component of various ...immune receptor signalling pathways. Here, we show that LUBAC forms part of the TRAIL‐R‐associated complex I as well as of the cytoplasmic TRAIL‐induced complex II. In both of these complexes, HOIP limits caspase‐8 activity and, consequently, apoptosis whilst being itself cleaved in a caspase‐8‐dependent manner. Yet, by limiting the formation of a RIPK1/RIPK3/MLKL‐containing complex, LUBAC also restricts TRAIL‐induced necroptosis. We identify RIPK1 and caspase‐8 as linearly ubiquitinated targets of LUBAC following TRAIL stimulation. Contrary to its role in preventing TRAIL‐induced RIPK1‐independent apoptosis, HOIP presence, but not its activity, is required for preventing necroptosis. By promoting recruitment of the IKK complex to complex I, LUBAC also promotes TRAIL‐induced activation of NF‐κB and, consequently, the production of cytokines, downstream of FADD, caspase‐8 and cIAP1/2. Hence, LUBAC controls the TRAIL signalling outcome from complex I and II, two platforms which both trigger cell death and gene activation.
Synopsis
The linear ubiquitin chain assembly complex (LUBAC), known to play key role in various immune receptor pathways, is identified as a crucial regulator of TRAIL‐induced signalling complexes, restricting apoptosis and necroptosis while promoting cytokine production.
TRAIL‐induced complex I and II both act as death‐inducing and gene‐activatory signalling platforms.
LUBAC is recruited to TRAIL complex I downstream of FADD, caspase‐8 and cIAP1/2, yet independently of RIPK1.
LUBAC is recruited to complex I and II in TRAIL signalling and restricts TRAIL‐induced necroptosis and apoptosis.
LUBAC promotes gene expression and cytokine production by recruiting the IKK complex to TRAIL complexes I and II.
LUBAC emerges as a crucial component of TRAIL signalling complexes I and II, restricting apoptosis and necroptosis while promoting cytokine production.
The linear ubiquitin chain assembly complex (LUBAC), composed of HOIP, HOIL-1 and SHARPIN, is required for optimal TNF-mediated gene activation and to prevent cell death induced by TNF. Here, we ...demonstrate that keratinocyte-specific deletion of HOIP or HOIL-1 (E-KO) results in severe dermatitis causing postnatal lethality. We provide genetic and pharmacological evidence that the postnatal lethal dermatitis in Hoip
and Hoil-1
mice is caused by TNFR1-induced, caspase-8-mediated apoptosis that occurs independently of the kinase activity of RIPK1. In the absence of TNFR1, however, dermatitis develops in adulthood, triggered by RIPK1-kinase-activity-dependent apoptosis and necroptosis. Strikingly, TRAIL or CD95L can redundantly induce this disease-causing cell death, as combined loss of their respective receptors is required to prevent TNFR1-independent dermatitis. These findings may have implications for the treatment of patients with mutations that perturb linear ubiquitination and potentially also for patients with inflammation-associated disorders that are refractory to inhibition of TNF alone.
TNF-related apoptosis-inducing ligand (TRAIL) receptor 2 (TRAIL-R2) can induce apoptosis in cancer cells upon crosslinking by TRAIL. However, TRAIL-R2 is highly expressed by many cancers suggesting ...pro-tumor functions. Indeed, TRAIL/TRAIL-R2 also activate pro-inflammatory pathways enhancing tumor cell invasion, migration, and proliferation. In addition, nuclear TRAIL-R2 (nTRAIL-R2) promotes malignancy by inhibiting miRNA let-7-maturation. Here, we show that TRAIL-R2 interacts with the tumor suppressor protein p53 in the nucleus, assigning a novel pro-tumor function to TRAIL-R2. Knockdown of TRAIL-R2 in p53 wild-type cells increases the half-life of p53 and the expression of its target genes, whereas its re-expression decreases p53 protein levels. Interestingly, TRAIL-R2 also interacts with promyelocytic leukemia protein (PML), a major regulator of p53 stability. PML-nuclear bodies are also the main sites of TRAIL-R2/p53 co-localization. Notably, knockdown or destruction of PML abolishes the TRAIL-R2-mediated regulation of p53 levels. In summary, our finding that nTRAIL-R2 facilitates p53 degradation and thereby negatively regulates p53 target gene expression provides insight into an oncogenic role of TRAIL-R2 in tumorigenesis that particularly manifests in p53 wild-type tumors.
The linear ubiquitin chain assembly complex (LUBAC), consisting of SHANK-associated RH-domain-interacting protein (SHARPIN), heme-oxidized IRP2 ubiquitin ligase-1 (HOIL-1), and HOIL-1-interacting ...protein (HOIP), is a critical regulator of inflammation and immunity. This is highlighted by the fact that patients with perturbed linear ubiquitination caused by mutations in the Hoip or Hoil-1 genes, resulting in knockouts of these proteins, may simultaneously suffer from immunodeficiency and autoinflammation. TLR3 plays a crucial, albeit controversial, role in viral infection and tissue damage. We identify a pivotal role of LUBAC in TLR3 signaling and discover a functional interaction between LUBAC components and TLR3 as crucial for immunity to influenza A virus infection. On the biochemical level, we identify LUBAC components as interacting with the TLR3-signaling complex (SC), thereby enabling TLR3-mediated gene activation. Absence of LUBAC components increases formation of a previously unrecognized TLR3-induced death-inducing SC, leading to enhanced cell death. Intriguingly, excessive TLR3-mediated cell death, induced by double-stranded RNA present in the skin of SHARPIN-deficient chronic proliferative dermatitis mice (cpdm), is a major contributor to their autoinflammatory skin phenotype, as genetic coablation of Tlr3 substantially ameliorated cpdm dermatitis. Thus, LUBAC components control TLR3-mediated innate immunity, thereby preventing development of immunodeficiency and autoinflammation.
Despite its name, signalling induced by the tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is versatile. Besides eliciting cell death by both apoptosis and necroptosis, TRAIL ...can also induce migration, proliferation, and cytokine production in cancerous and non-cancerous cells. Unravelling the mechanisms regulating the intricate balance between these different outputs could therefore facilitate our understanding of the role of TRAIL in tissue homeostasis, immunity, and cancer. Ubiquitination and its reversal, deubiquitination, are crucial modulators of immune receptor signalling. This review discusses recent progress on the orchestration of TRAIL signalling outcomes by ubiquitination of various components of the signalling complexes, our understanding of the molecular switches that decide between cell death and gene activation, and what remains to be discovered.
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced complexes I and II both act as cell death-inducing and gene-activatory signalling platforms.
The core components of TRAIL-induced signalling – TRAIL receptor (TRAIL-R)1/2, FADD, caspase-8, RIPK1, and cFLIPL/S – are regulated by ubiquitination.
Ubiquitin writers, erasers, and binders such as TRAF2, cIAP1/2, the linear ubiquitin chain-assembly complex (LUBAC), A20, TABs, and NEMO are major regulatory components in TRAIL-induced signalling complexes.
Both degradative (K48) and non-degradative (K63 and M1) polyubiquitination events control the TRAIL-induced signalling outcome.
Tight regulation of the function and expression of TRAIL-induced signalling complex components by ubiquitination is required to ensure appropriate activation of downstream signalling outputs.
Due to their decisive regulatory roles in mediating TRAIL signalling outputs in cancer cells, modulators of ubiquitination are promising therapeutic targets.
The linear ubiquitin chain assembly complex (LUBAC) is required for optimal gene activation and prevention of cell death upon activation of immune receptors, including TNFR1
. Deficiency in the LUBAC ...components SHARPIN or HOIP in mice results in severe inflammation in adulthood or embryonic lethality, respectively, owing to deregulation of TNFR1-mediated cell death
. In humans, deficiency in the third LUBAC component HOIL-1 causes autoimmunity and inflammatory disease, similar to HOIP deficiency, whereas HOIL-1 deficiency in mice was reported to cause no overt phenotype
. Here we show, by creating HOIL-1-deficient mice, that HOIL-1 is as essential for LUBAC function as HOIP, albeit for different reasons: whereas HOIP is the catalytically active component of LUBAC, HOIL-1 is required for LUBAC assembly, stability and optimal retention in the TNFR1 signalling complex, thereby preventing aberrant cell death. Both HOIL-1 and HOIP prevent embryonic lethality at mid-gestation by interfering with aberrant TNFR1-mediated endothelial cell death, which only partially depends on RIPK1 kinase activity. Co-deletion of caspase-8 with RIPK3 or MLKL prevents cell death in Hoil-1
(also known as Rbck1
) embryos, yet only the combined loss of caspase-8 with MLKL results in viable HOIL-1-deficient mice. Notably, triple-knockout Ripk3
Casp8
Hoil-1
embryos die at late gestation owing to haematopoietic defects that are rescued by co-deletion of RIPK1 but not MLKL. Collectively, these results demonstrate that both HOIP and HOIL-1 are essential LUBAC components and are required for embryogenesis by preventing aberrant cell death. Furthermore, they reveal that when LUBAC and caspase-8 are absent, RIPK3 prevents RIPK1 from inducing embryonic lethality by causing defects in fetal haematopoiesis.
Many cancers harbor oncogenic mutations of KRAS. Effectors mediating cancer progression, invasion, and metastasis in KRAS-mutated cancers are only incompletely understood. Here we identify cancer ...cell-expressed murine TRAIL-R, whose main function ascribed so far has been the induction of apoptosis as a crucial mediator of KRAS-driven cancer progression, invasion, and metastasis and in vivo Rac-1 activation. Cancer cell-restricted genetic ablation of murine TRAIL-R in autochthonous KRAS-driven models of non-small-cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) reduces tumor growth, blunts metastasis, and prolongs survival by inhibiting cancer cell-autonomous migration, proliferation, and invasion. Consistent with this, high TRAIL-R2 expression correlates with invasion of human PDAC into lymph vessels and with shortened metastasis-free survival of KRAS-mutated colorectal cancer patients.
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•mTRAIL-R promotes KRAS-driven lung and pancreatic cancer growth and metastasis•Human TRAIL-R2 promotes tumor growth, migration, invasion, and metastasis•Endogenous mTRAIL-R constitutively activates Rac1 in vivo in tumors•TRAIL-R2 expression positively correlates with the onset of metastasis in patients
von Karstedt et al. show that mouse TRAIL-R and human TRAIL-R2, but not TRAIL-R1, are important for the progression, invasion, and metastasis of KRAS-mutant tumors through the regulation of Rac-1.
Abstract
Tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) is known for specifically killing many cancer cells. This has led to the clinical development of several agonists for ...TRAIL-Rs. However, while some cancer cells die in response to TRAIL, most primary cancer cells are resistant to TRAIL-based monotherapy. In resistant cells, TRAIL signaling can induce non-apoptotic, tumor-supporting effects. Hence, efficient therapy design requires understanding of the bivalent nature of TRAIL signaling. Here we demonstrate that, on the one hand, TRAIL–TRAIL-R signaling in cancer cells elicits the production of cytokines, most importantly CCL2, which promote the accumulation of alternatively activated, M2-like myeloid cells in the tumor microenvironment, consequently promoting tumor growth via a CCL2/CCR2 axis. On the other hand, we identified CDK9 inhibition as a powerful means to render many TRAIL-resistant cancer cells highly sensitive to TRAIL-induced apoptosis. Importantly, this combination was also highly effective in vivo and led to significant tumor regression in mouse models of lung cancer. Therefore, in certain cancer patients antagonizing endogenous TRAIL–TRAIL-R signaling may modulate the tumor microenvironment in favour of tumor regression, while in other cancer patients the combination of TRAIL-R agonists with CDK9 inhibitors should be considered as a highly active alternative therapy.
Citation Format: Antonella Montinaro, Torsten Hartwig, Silvia von Karstedt, Itziar Areso Zubiaur, Johannes Lemke, Lucia Taraborelli, Silvia Surinova, Mona A. El-Bahrawy, Henning Walczak. Characterization and therapeutic harnessing of TRAIL’s pro-tumorigenic and pro-apoptotic functions in cancer abstract. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B18.
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