Human innate immune cell crosstalk induces melanoma cell senescence.
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ABSTRACT:
SUBMITTER: Funck F
PROVIDER: S-EPMC7470184 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundImmune-stimulatory agents, like agonists of the innate immune receptor RIG-I, are currently tested in clinical trials as an intratumoral treatment option for patients with unresectable melanoma, aiming to enhance anti-tumor T cell responses. Switching of melanoma toward a dedifferentiated cell state has recently been linked to T cell and therapy resistance. It remains to be determined whether RIG-I agonists affect melanoma differentiation, potentially leading to T cell resistance.MethodsPatient metastases-derived melanoma cell lines were treated with the synthetic RIG-I agonist 3pRNA, and effects on tumor cell survival, phenotype and differentiation were determined. Transcriptomic data sets from cell lines and metastases were analyzed for associations between RIG-I (DDX58) and melanoma differentiation markers and used to define signaling pathways involved in RIG-I-driven dedifferentiation. The impact of 3pRNA-induced melanoma dedifferentiation on CD8 T cell activation was studied in autologous tumor T cell models.ResultsRIG-I activation by 3pRNA induced apoptosis in a subpopulation of melanoma cells, while the majority of tumor cells switched into a non-proliferative cell state. Those persisters displayed a dedifferentiated cell phenotype, marked by downregulation of the melanocytic lineage transcription factor MITF and its target genes, including melanoma differentiation antigens (MDA). Transition into the MITFlow/MDAlow cell state was JAK-dependent, with some cells acquiring nerve growth factor receptor expression. MITFlow/MDAlow persisters switched back to the proliferative differentiated cell state when RIG-I signaling declined. Consistent with our in vitro findings, an association between melanoma dedifferentiation and high RIG-I (DDX58) levels was detected in transcriptomic data from patient metastases. Notably, despite their dedifferentiated cell phenotype, 3pRNA-induced MITFlow/MDAlow persisters were still efficiently targeted by autologous CD8 tumor-infiltrating T lymphocytes (TILs).ConclusionsOur results demonstrate that RIG-I signaling in melanoma cells drives a transient phenotypic switch toward a non-proliferative dedifferentiated persister cell state. Despite their dedifferentiation, those persisters are highly immunogenic and sensitive toward autologous TILs, challenging the concept of melanoma dedifferentiation as a general indicator of T cell resistance. In sum, our findings support the application of RIG-I agonists as a therapeutic tool for the generation of long-term clinical benefit in non-resectable melanoma.
| S-EPMC9196182 | biostudies-literature
Project description:Temozolomide (TMZ), a DNA alkylating agent used in the treatment of melanoma, is believed to mediate its effect by addition of a methyl group to the O(6) position of guanine in DNA. Resistance to the agent may be in part due to the activity of O(6)-methylguanine-DNA methyl transferase (MGMT). In the present study, we show that sensitivity of melanoma cells to TMZ was dependent on their p53 status and levels of MGMT. Analysis of the mechanisms underlying reduced viability showed no evidence for induction of apoptosis even though marked levels of apoptosis was seen in TK6 lymphoma cells. Sensitivity of melanoma cells was associated with p53-dependent G2/M cell cycle arrest and induction of senescence. To verify the role of p53, the assays were repeated in presence of pifithrin-alpha, an inhibitor of p53. This resulted in increased viability of melanoma cells with wild-type p53 and reversed G2/M cell cycle arrest. Paradoxically, apoptosis was increased in melanoma but decreased as expected in TK6 lymphoma cells. These results are consistent with the view that TMZ is relatively ineffective against melanoma due to defective apoptotic signalling resulting from activation of p53. The nature of the defects in apoptotic signalling remains to be explored.
| S-EPMC2360470 | biostudies-literature
Project description:The tumor microenvironment encompasses various innate immune cells which regulate tumor progression. Exploiting innate immune cells is a new frontier of cancer immunotherapy. However, the classical surface markers for cell-type classification cannot always well-conclude the phenotype, which will further hinge our understanding. The innate immune cells include dendritic cells, monocytes/macrophages, natural killer cells, and innate lymphoid cells. They play important roles in tumor growth and survival, in some cases promoting cancer, in other cases negating cancer. The precise characterization of innate immune cells at the single-cell level will boost the potential of cancer immunotherapy. With the development of single-cell RNA sequencing technology, the transcriptome of each cell in the tumor microenvironment can be dissected at a single-cell level, which paves a way for a better understanding of the cell type and its functions. Here, we summarize the subtypes and functions of innate immune cells in the tumor microenvironment based on recent literature on single-cell technology. We provide updates on recent achievements and prospects for how to exploit novel functions of tumor-associated innate immune cells and target them for cancer immunotherapy.
| S-EPMC9140036 | biostudies-literature
Project description:The innate immune system provides the first response to infection and is now recognized to be partially pathogen-specific. Mycobacterium tuberculosis (MTB) is able to subvert the innate immune response and survive inside macrophages. Curiously, only 5-10% of otherwise healthy individuals infected with MTB develop active tuberculosis (TB). We do not yet understand the genetic basis underlying this individual-specific susceptibility. Moreover, we still do not know which properties of the innate immune response are specific to MTB infection. To identify immune responses that are specific to MTB, we infected macrophages with eight different bacteria, including different MTB strains and related mycobacteria, and studied their transcriptional response. We identified a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. This subset includes genes involved in phagosome maturation, superoxide production, response to vitamin D, macrophage chemotaxis, and sialic acid synthesis. We suggest that genetic variants that affect the function or regulation of these genes should be considered candidate loci for explaining TB susceptibility.
| S-EPMC4653619 | biostudies-literature
Project description:Merkel cell polyomavirus (MCPyV) infects most of the human population asymptomatically, but in rare cases it leads to a highly aggressive skin cancer called Merkel cell carcinoma (MCC). MCC incidence is much higher in aging and immunocompromised populations. The epidemiology of MCC suggests that dysbiosis between the host immune response and the MCPyV infectious cycle could contribute to the development of MCPyV-associated MCC. Insufficient restriction of MCPyV by normal cellular processes, for example, could promote the incidental oncogenic MCPyV integration events and/or entry into the original cell of MCC. Progress toward understanding MCPyV biology has been hindered by its narrow cellular tropism. Our discovery that primary human dermal fibroblasts (HDFs) support MCPyV infection has made it possible to closely model cellular responses to different stages of the infectious cycle. The present study reveals that the onset of MCPyV replication and early gene expression induces an inflammatory cytokine and interferon-stimulated gene (ISG) response. The cGAS-STING pathway, in coordination with NF-κB, mediates induction of this innate immune gene expression program. Further, silencing of cGAS or NF-κB pathway factors led to elevated MCPyV replication. We also discovered that the PYHIN protein IFI16 localizes to MCPyV replication centers but does not contribute to the induction of ISGs. Instead, IFI16 upregulates inflammatory cytokines in response to MCPyV infection by an alternative mechanism. The work described herein establishes a foundation for exploring how changes to the skin microenvironment induced by aging or immunodeficiency might alter the fate of MCPyV and its host cell to encourage carcinogenesis. IMPORTANCE MCC has a high rate of mortality and an increasing incidence. Immune-checkpoint therapies have improved the prognosis of patients with metastatic MCC. Still, a significant proportion of the patients fail to respond to immune-checkpoint therapies or have a medical need for iatrogenic immune-suppression. A greater understanding of MCPyV biology could inform targeted therapies for MCPyV-associated MCC. Moreover, cellular events preceding MCC oncogenesis remain largely unknown. The present study aims to explore how MCPyV interfaces with innate immunity during its infectious cycle. We describe how MCPyV replication and/or transcription elicit an innate immune response via cGAS-STING, NF-κB, and IFI16. We also explore the effects of this response on MCPyV replication. Our findings illustrate how healthy cellular conditions may allow low-level infection that evades immune destruction until highly active replication is restricted by host responses. Conversely, pathological conditions could result in unbridled MCPyV replication that licenses MCC tumorigenesis.
| S-EPMC8437356 | biostudies-literature
Project description:Nuclear dot protein 52 kDa (NDP52, also known as CALCOCO2) functions as a selective autophagy receptor. The linear ubiquitin chain assembly complex (LUBAC) specifically generates the N-terminal Met1-linked linear ubiquitin chain, and regulates innate immune responses, such as nuclear factor-κB (NF-κB), interferon (IFN) antiviral, and apoptotic pathways. Although NDP52 and LUBAC cooperatively regulate bacterial invasion-induced xenophagy, their functional crosstalk remains enigmatic. Here we show that NDP52 suppresses canonical NF-κB signaling through the broad specificity of ubiquitin-binding at the C-terminal UBZ domain. Upon TNF-α-stimulation, NDP52 associates with LUBAC through the HOIP subunit, but does not disturb its ubiquitin ligase activity, and has a modest suppressive effect on NF-κB activation by functioning as a component of TNF-α receptor signaling complex I. NDP52 also regulates the TNF-α-induced apoptotic pathway, but not doxorubicin-induced intrinsic apoptosis. A chemical inhibitor of LUBAC (HOIPIN-8) cancelled the increased activation of the NF-κB and IFN antiviral pathways, and enhanced apoptosis in NDP52-knockout and -knockdown HeLa cells. Upon Salmonella-infection, colocalization of Salmonella, LC3, and linear ubiquitin was detected in parental HeLa cells to induce xenophagy. Treatment with HOIPIN-8 disturbed the colocalization and facilitated Salmonella expansion. In contrast, HOIPIN-8 showed little effect on the colocalization of LC3 and Salmonella in NDP52-knockout cells, suggesting that NDP52 is a weak regulator in LUBAC-mediated xenophagy. These results indicate that the crosstalk between NDP52 and LUBAC regulates innate immune responses, apoptosis, and xenophagy.
| S-EPMC8017197 | biostudies-literature
Project description:BackgroundMicro RNAs (miRs) have emerged as key regulators during oncogenesis. They have been found to regulate cell proliferation, differentiation, and apoptosis. Mir-125b has been identified as an oncomir in various forms of tumours, but we have previously proposed that miR-125b is a suppressor of lymph node metastasis in cutaneous malignant melanoma. Our goal was therefore to further examine this theory.MethodsWe used in-situ-hybridization to visualise miR-125b expression in primary tumours and in lymph node metastasis. Then using a miRVector plasmid containing a miR-125b-1 insert we transfected melanoma cell line Mel-Juso and then investigated the effect of the presence of a stable overexpression of miR-125b on growth by western blotting, flow cytometry and ?-galactosidase staining. The tumourogenicity of the transfected cells was tested using a murine model and the tumours were further examined with in-situ-hybridization.ResultsIn primary human tumours and in lymph node metastases increased expression of miR-125b was found in single, large tumour cells with abundant cytoplasm. A stable overexpression of miR-125b in human melanoma cell line Mel-Juso resulted in a G0/G1 cell cycle block and emergence of large cells expressing senescence markers: senescence-associated beta-galactosidase, p21, p27 and p53. Mel-Juso cells overexpressing miR-125b were tumourigenic in mice, but the tumours exhibited higher level of cell senescence and decreased expression of proliferation markers, cyclin D1 and Ki67 than the control tumours.ConclusionsOur results confirm the theory that miR-125b functions as a tumour supressor in cutaneous malignant melanoma by regulating cellular senescence, which is one of the central mechanisms protecting against the development and progression of malignant melanoma.
| S-EPMC4021480 | biostudies-literature
Project description:MicroRNAs regulate gene expression by repressing translation or directing sequence-specific degradation of their complementary mRNA. We recently reported that miR-203 is down-regulated, and its exogenous expression inhibits cell growth in canine oral malignant melanoma tissue specimens as well as in canine and human malignant melanoma cells. A microRNA target database predicted E2F3 and ZBP-89 as putative targets of microRNA-203 (miR-203). The expression levels of E2F3a, E2F3b, and ZBP-89 were markedly up-regulated in human malignant melanoma Mewo cells compared with those in human epidermal melanocytes. miR-203 significantly suppressed the luciferase activity of reporter plasmids containing the 3'-UTR sequence of either E2F3 or ZBP-89 complementary to miR-203. The ectopic expression of miR-203 in melanoma cells reduced the levels of E2F3a, E2F3b, and ZBP-89 protein expression. At the same time, miR-203 induced cell cycle arrest and senescence phenotypes, such as elevated expression of hypophosphorylated retinoblastoma and other markers for senescence. Silencing of E2F3, but not of ZBP-89, inhibited cell growth and induced cell cycle arrest and senescence. These results demonstrate a novel role for miR-203 as a tumor suppressor acting by inducing senescence in melanoma cells.
| S-EPMC3320925 | biostudies-literature
Project description:BackgroundThe application of immune-based therapies has revolutionized cancer treatment. Yet how the immune system responds to phenotypically heterogeneous populations within tumors is poorly understood. In melanoma, one of the major determinants of phenotypic identity is the lineage survival oncogene MITF that integrates diverse microenvironmental cues to coordinate melanoma survival, senescence bypass, differentiation, proliferation, invasion, metabolism and DNA damage repair. Whether MITF also controls the immune response is unknown.MethodsBy using several mouse melanoma models, we examine the potential role of MITF to modulate the anti-melanoma immune response. ChIP-seq data analysis, ChIP-qPCR, CRISPR-Cas9 genome editing, and luciferase reporter assays were utilized to identify ADAM10 as a direct MITF target gene. Western blotting, confocal microscopy, flow cytometry, and natural killer (NK) cytotoxicity assays were used to determine the underlying mechanisms by which MITF-driven phenotypic plasticity modulates melanoma NK cell-mediated killing.ResultsHere we show that MITF regulates expression of ADAM10, a key sheddase that cleaves the MICA/B family of ligands for NK cells. By controlling melanoma recognition by NK-cells MITF thereby controls the melanoma response to the innate immune system. Consequently, while melanoma MITFLow cells can be effectively suppressed by NK-mediated killing, MITF-expressing cells escape NK cell surveillance.ConclusionOur results reveal how modulation of MITF activity can impact the anti-melanoma immune response with implications for the application of anti-melanoma immunotherapies.
| S-EPMC8015040 | biostudies-literature
Project description:MicroRNAs (miRNAs) regulate gene expression by repressing translation or directing sequence-specific degradation of complementary mRNA. Here, we report that expression of miR-205 is significantly suppressed in melanoma specimens when compared with nevi and is correlated inversely with melanoma progression. miRNA target databases predicted E2F1 and E2F5 as putative targets. The expression levels of E2F1 and E2F5 were correlated inversely with that of miR-205 in melanoma cell lines. miR-205 significantly suppressed the luciferase activity of reporter plasmids containing the 3'-UTR sequences complementary to either E2F1 or E2F5. Overexpression of miR-205 in melanoma cells reduced E2F1 and E2F5 protein levels. The proliferative capacity of melanoma cells was suppressed by miR-205 and mediated by E2F-regulated AKT phosphorylation. miR-205 overexpression resulted in induction of apoptosis, as evidenced by increased cleaved caspase-3, poly-(ADP-ribose) polymerase, and cytochrome c release. Stable overexpression of miR-205 suppressed melanoma cell proliferation, colony formation, and tumor cell growth in vivo and induced a senescence phenotype accompanied by elevated expression of p16INK4A and other markers for senescence. E2F1 overexpression in miR-205-expressing cells partially reversed the effects on melanoma cell growth and senescence. These results demonstrate a novel role for miR-205 as a tumor suppressor in melanoma.
| S-EPMC3089503 | biostudies-literature