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Dendritic cells (DCs) are promising targets for cancer immunotherapies because of their central role in the initiation and control of immune responses. The rare cDC1 population is of particular interest because of its remarkable ability to cross-present antigens (Ag) to CD8+ T cells, to promote Th1 cell polarization and NK cell activation and recruitment. However, the spatial organization and specific functions of cDC1s in response to immunotherapy remain to be clearly characterized in human tumors. Here, we implemented a multiplexed immunofluorescence analysis pipeline coupled with computational image analysis to determine the spatial organization of the cDC1 subset in a cohort of skin lesions from advanced melanoma patients treated with immune checkpoint inhibitors (ICI). For this, we performed a whole-slide image analysis of cDC1 infiltration and distribution as well as their spatial interactions with key immune partners such as CD8+ T cells and pDC according to the response of patients to ICI. We also analyzed LAMP3+-DC, which correspond to a mature subset of tumor-infiltrating DCs. Distance and cell network analyses demonstrated that cDC1s exhibited a scattered distribution compared to tumor-infiltrating pDCs and LAMP3+-DCs, which were preferentially organized in dense areas with high homotypic connections. Interestingly, the proximity and interactions between CD8+ T cells and cDC1s were positively associated with the response to ICI. In conclusion, our study unravels the complex spatial organization of cDC1s and their interactions with CD8+ T cells in melanoma patient lesions, shedding light on their pivotal role in shaping the response to ICI.

Whereas immunotherapies have revolutionized the treatment of different solid and hematologic cancers, their efficacy in nodal peripheral T-cell lymphomas (PTCL) is limited, due to a lack of understanding of the immune response they trigger. To fully characterize the immune tumor microenvironment (TME) of PTCL, we performed spectral flow cytometry analyses on 11 angioimmunoblastic T-cell lymphomas (AITL), 7 PTCL, not otherwise specified (PTCL, NOS) lymph node samples, and 10 non-tumoral control samples. The PTCL TME contained a larger proportion of regulatory T cells and exhausted CD8+ T cells, with enriched expression of druggable immune checkpoints. Interestingly, CD39 expression was up-regulated at the surface of most immune cells, and a multi-immunofluorescence analysis on a retrospective cohort of 43 AITL patients demonstrated a significant association between high CD39 expression by T cells and poor patient prognosis. Together, our study unravels the complex TME of nodal PTCL, identifies targetable immune checkpoints, and highlights CD39 as a novel prognostic factor.

Gestational trophoblastic diseases derived from the chorionic-type intermediate trophoblast include benign placental site nodule (PSN) and malignant epithelioid trophoblastic tumor (ETT). Among PSNs, the World Health Organization classification introduced a new entity named atypical placental site nodule (APSN), corresponding to an ETT precursor, for which diagnostic criteria remain unclear, leading to a risk of overdiagnosis and difficulties in patient management. We retrospectively studied 8 PSNs, 7 APSNs, and 8 ETTs to better characterize this new entity and performed immunohistochemical analysis (p63, human placental lactogen, Cyclin E, and Ki67), transcriptional analysis using the NanoString method to quantify the expression of 760 genes involved in the main tumorigenesis pathways, and RNA sequencing to identify fusion transcripts. The immunohistochemical analysis did not reveal any significant difference in Cyclin E expression among the 3 groups (P = .476), whereas the Ki67 index was significantly (P < .001) higher in ETT samples than in APSN and PSN samples. None of the APSN samples harbored the LPCAT1::TERT fusion transcripts, in contrast to 1 of 6 ETT samples, as previously described in 2 of 3 ETT samples. The transcriptomic analysis allowed robust clustering of ETTs distinct from the APSN/PSN group but failed to differentiate APSNs from PSNs. Indeed, only 7 genes were differentially expressed between PSN and APSN samples; CCL19 upregulation and EPCAM downregulation were the most distinguishing features of APSNs. In contrast, 80 genes differentiated ETTs from APSNs, establishing a molecular signature for ETT. Gene set analysis identified significant enrichments in the DNA damage repair, immortality and stemness, and cell cycle signaling pathways when comparing ETTs and APSNs. These results suggested that APSN might not represent a distinct entity but rather a transitional stage between PSN and ETT. RNA sequencing and the transcriptional signature of ETT described herein could serve as triage for APSN from curettage or biopsy material, enabling the identification of cases that need further clinical investigations., (Copyright © 2022 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Background: The efficacy of immunotherapies in metastatic melanoma depends on a robust T cell infiltration. Oncogenic alterations of tumor cells have been associated to T cell exclusion. Identifying novel cancer cell-intrinsic non-genetic mechanisms of immune escape, the targeting of which would reinstate T cell recruitment, would allow to restore the response to anti-programmed cell death protein 1 (PD-1) antibody therapy. The epithelial-to-mesenchymal transition (EMT)-inducing transcription factor ZEB1 is a major regulator of melanoma cell plasticity, driving resistance to mitogen-activated protein kinase (MAPK) targeted therapies. We thus wondered whether ZEB1 signaling in melanoma cells may promote immune evasion and resistance to immunotherapy., Methods: We evaluated the putative correlation between ZEB1 expression in melanoma cells and the composition of the immune infiltrate in a cohort of 60 human melanoma samples by combining transcriptomic (RNA-sequencing) and seven-color spatial multi-immunofluorescence analyses. Algorithm-based spatial reconstitution of tumors allowed the quantification of CD8 + , CD4 + T cells number and their activation state (PD-1, Ki67). ZEB1 gain-of-function or loss-of-function approaches were then implemented in syngeneic melanoma mouse models, followed by monitoring of tumor growth, quantification of immune cell populations frequency and function by flow cytometry, cytokines secretion by multiplex analyses. Chromatin-immunoprecipitation was used to demonstrate the direct binding of this transcription factor on the promoters of cytokine-encoding genes. Finally, the sensitivity to anti-PD-1 antibody therapy upon ZEB1 gain-of-function or loss-of-function was evaluated., Results: Combined spatial and transcriptomic analyses of the immune infiltrates in human melanoma samples demonstrated that ZEB1 expression in melanoma cells is associated with decreased CD8 + T cell infiltration, independently of β-catenin pathway activation. ZEB1 ectopic expression in melanoma cells impairs CD8 + T cell recruitment in syngeneic mouse models, resulting in tumor immune evasion and resistance to immune checkpoint blockade. Mechanistically, we demonstrate that ZEB1 directly represses the secretion of T cell-attracting chemokines, including CXCL10. Finally, Zeb1 knock-out, by promoting CD8 + T cell infiltration, synergizes with anti-PD-1 antibody therapy in promoting tumor regression., Conclusions: We identify the ZEB1 transcription factor as a key determinant of melanoma immune escape, highlighting a previously unknown therapeutic target to increase efficacy of immunotherapy in melanoma., Trial Registration Number: NCT02828202., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: Gastric-type endocervical carcinoma is a rare entity of carcinoma of the cervix. In contrast to the intestinal type, the gastric type is not related to Human Papilloma Virus (HPV) infection and has been reported to be much more aggressive than the usual type. Oncogenic pathways involved in this poor-prognosis phenotype are largely unexplored., Methods: We compared activation of the main signaling pathways involved in cancer progression between the intestinal- (n = 5), gastric- (n = 6) and usual-type (n = 6) adenocarcinomas of the cervix using a targeted transcriptomic approach (expression of 770 genes) on FFPE samples., Results: We identified a gene-expression signature composed of 11 genes that allows the classification of these endocervical carcinoma as three distinct molecular entities. There were similarities between mucinous endocervical carcinomas (gastric and intestinal types) despite difference in pathogenesis related to HPV infection. Among HPV-related endocervical carcinoma, the intestinal type could be molecularly distinguished from the usual type by high expression of EIF2AK3 and low expression of PPFIBP2 genes, supporting its classification as a distinct entity. Overexpression of TAL1 and S1PR1 genes were characteristic of the gastric type. The usual type was characterized by high expression of occludin and VAV3 genes. Tight junction disruptions might play an essential role in the metastatic potential of mucinous endocervical carcinoma with concomitant loss of OCLN and claudin 4 proteins. An overexpression of NTRK1 transcript was observed in mucinous endocervical carcinomas when compared to the usual type., Conclusions: This transcriptomic study identified a signature that supports the classification of endocervical carcinomas as three distinct entities: usual-, intestinal- and gastric-type. It also points out to disruption of tight junctions as a potential mechanism of metastatic dissemination of these rare tumors., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Ectodysplasin receptor EDAR is seen as a typical Tumor Necrosis Factor receptor (TNFR) family member known to interact with its ligand Eda-A1, and signaling mainly through the nuclear factor-kappaB (NF-κB) and c-jun N-terminal kinases pathways. Mutations in genes that encode proteins involved in EDAR transduction cascade cause anhidrotic ectodermal dysplasia. Here, we report an unexpected pro-apoptotic activity of EDAR when unbound to its ligand Eda-A1, which is independent of NF-κB pathway. Contrarily to other death receptors, EDAR does recruit caspase-8 to trigger apoptosis but solely upon ligand withdrawal, thereby behaving as the so-called dependence receptors. We propose that pro-apoptotic activity of unbound EDAR confers it a tumor suppressive activity. Along this line, we identified loss-of-pro-apoptotic function mutations in EDAR gene in human melanoma. Moreover, we show that the invalidation of EDAR in mice promotes melanoma progression in a B-Raf mutant background. Together, these data support the view that EDAR constrains melanoma progression by acting as a dependence receptor.

Phenotypic plasticity and subsequent generation of intratumoral heterogeneity underly key traits in malignant melanoma such as drug resistance and metastasis. Melanoma plasticity promotes a switch between proliferative and invasive phenotypes characterized by different transcriptional programs of which MITF is a critical regulator. Here, we show that the acid ceramidase ASAH1, which controls sphingolipid metabolism, acted as a rheostat of the phenotypic switch in melanoma cells. Low ASAH1 expression was associated with an invasive behavior mediated by activation of the integrin alphavbeta5-FAK signaling cascade. In line with that, human melanoma biopsies revealed heterogeneous staining of ASAH1 and low ASAH1 expression at the melanoma invasive front. We also identified ASAH1 as a new target of MITF, thereby involving MITF in the regulation of sphingolipid metabolism. Together, our findings provide new cues to the mechanisms underlying the phenotypic plasticity of melanoma cells and identify new anti-metastatic targets.

Targeted therapies with MAPK inhibitors (MAPKi) are faced with severe problems of resistance in BRAF-mutant melanoma. In parallel to the acquisition of genetic mutations, melanoma cells may also adapt to the drugs through phenotype switching. The ZEB1 transcription factor, a known inducer of EMT and invasiveness, is now considered as a genuine oncogenic factor required for tumor initiation, cancer cell plasticity, and drug resistance in carcinomas. Here, we show that high levels of ZEB1 expression are associated with inherent resistance to MAPKi in BRAF V 600 -mutated cell lines and tumors. ZEB1 levels are also elevated in melanoma cells with acquired resistance and in biopsies from patients relapsing while under treatment. ZEB1 overexpression is sufficient to drive the emergence of resistance to MAPKi by promoting a reversible transition toward a MITF low /p75 high stem-like and tumorigenic phenotype. ZEB1 inhibition promotes cell differentiation, prevents tumorigenic growth in vivo, sensitizes naive melanoma cells to MAPKi, and induces cell death in resistant cells. Overall, our results demonstrate that ZEB1 is a major driver of melanoma cell plasticity, driving drug adaptation and phenotypic resistance to MAPKi., (© 2016 The Authors. Published under the terms of the CC BY 4.0 license.)