Biology subjects

Fournier, N.

Publications and source records attributed to Fournier, N..

8 recordsLinked to original sources

bioRxiv2026

Structural basis of phosphatidylserine enhancement of Gas6 ligand-induced Axl activation

TAMs (Tyro3, Axl, and MerTK) are receptor tyrosine kinases with primary roles in apoptotic clearance and immune suppression. In apoptosis, bridging complexes form between TAM receptors on phagocytic cells and TAM ligand bound to phosphatidylserine exposed on the surface of dying cells, but how these complexes form or why lipid is required for receptor activation is poorly understood. We present the first structures of a complete TAM receptor (Axl) and ligand (Gas6) 2:2 bridging complex with and without lipid, which suggest that the lipid functions to stabilize and promote active complexes. We also observe a stable 1:1 complex, presumed to be inactive, and provide evidence that these complexes are conversely able to form higher-order oligomers. We propose a mechanism for how lipids promote TAM receptor activation, providing a structural and biochemical basis for developing therapies that selectively target the lipid-dependent, immunosuppressive arm of TAM signaling exploited by tumors.

biophysics↗

bioRxiv2026

An IL-34-IGF-1 inflammatory axis fuels KRAS-mutant lung cancer progression

Macrophages are innate immune cells of embryonic or adult origin with tissue specific roles in homeostasis, disease surveillance, and wound repair that can be co-opted to promote tumor growth and spread1-11. An understanding of the specific roles of macrophage subsets in lung tumor initiation and progression could promote new therapeutic approaches for this deadly disease. Here, we show that KRASG12D mutations in lung epithelium drive proliferation of resident, embryonically-derived alveolar macrophages, which then promote tumor cell proliferation and protection from ferroptosis, leading to tumor progression. Using genetically engineered mouse models of mutant KRASG12D non-small cell lung cancer12,13, we found that alveolar macrophages accumulate by proliferation in response to tumor cell-secreted IL-34, recapitulating events observed in late embryonic lung development. Tumor alveolar macrophages in turn drive IGF-1-dependent tumor cell proliferation. Neutralization or deletion of IL-34 suppresses IGF-1 expression, reduces macrophage and tumor cell proliferation and inhibits tumor progression. High IL34 and IGF1 correlate with poor survival in KRASG12D/V lung adenocarcinomas and in other solid tumors, indicating that bi-directional proliferative signaling between resident macrophages and tumor cells can drive human lung tumor progression. These studies identify resident macrophage-tumor cell interactions as key interception points for lung cancer therapy.

cancer biology↗

bioRxiv2026

Neutrophil-Derived S100A8/A9 Drives Inflammation that Promotes Dnmt3a -Mutant Hematopoiesis

Clonal hematopoiesis (CH) is an age-associated condiion defined by over-representation of hematopoietic stem cells (HSCs) and their progeny carrying somatic mutations or variants that confer a selective advantage. CH is associated with increased risk of hematologic malignancies (1), cardiovascular disease and inflammatory bone loss (2, 3). Chronic inflammation is increasingly recognized as a central mediator of CH-mutant hematopoietic stem and progenitor cell (HSPC) expansion underlying CH (4). DNA methyltransferase 3a ( Dnmt3a )-mutant cells produce higher levels of tumor necrosis factor-α (TNFα) and interleukin-6 (IL-6) (5), and blocking these pathways reduces the competitive advantage of Dnmt3a -mutant HSPCs (4, 6). The upstream mediators initiating inflammatory signaling in CH are unknown. Strong candidates are S100A8 and S100A9, members of the S100 calcium-binding protein family that regulate inflammatory signaling in the hematopoietic system. These proteins form a heterodimer complex and activate innate immune signaling through receptors including Toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE) (7). S100A8/A9 signaling promotes production of pro-inflammatory cytokines and inflammasome activation leading to poor prognosis in myelodysplastic syndrome and myeloproliferative neoplasms (8, 9). Across multiple myeloid malignancies, neutrophils are the primary bone marrow (BM) source of this alarmin (8, 10, 11) and pharmacologic inhibition of S100A9 with tasquinimod reduces disease severity without disrupting normal hematopoiesis (10, 12). Given the role of S100A8/A9 in establishing an inflammatory milieu, here we investigated the role of S100A8/A9 in Dnmt3a -mutant hematopoiesis. We identify neutrophils as a major source of elevated S100A8/A9 in the BM of Dnmt3a -mutant mice and this increase correlates with production of the inflammatory cytokines TNFα and IL-6. We show that tasquinimod reduces TNFα and IL-6 levels and selectively reduces the Dnmt3a -mutant HSPC compartment.

Cell Biology↗

bioRxiv2026

Multiomic profiling of human and canine soft-tissue sarcomas reveals extensive molecular homology across species and identifies clinically relevant subgroups

Soft-tissue sarcoma (STS) are rare and heterogeneous mesenchymal tumours with over 100 recognized human subtypes. Despite advances in cytogenetic and molecular characterization, diagnostic precision and therapeutic options remain limited for most subtypes. Spontaneously occurring canine STS could represent valuable translational models, due to their higher incidence and clinical similarity to human counterparts. However, molecular cross-species comparisons of specific subtypes are largely missing. Here, we performed a tissue-resolved, cross-species analysis of tumour and matched adjacent normal tissue (NT) in human and canine fibrosarcoma (FSA) and myxofibrosarcoma (MFS) by laser-capture microdissection of FFPE specimens combined with RNAseq and LC-MS/MS. Multimodal profiling revealed FSA and MFS to represent a molecular continuum rather than distinct entities in both species, resulted in identification of clinically relevant subgroups based on immune activation, proliferative activity and copy number alterations, and identified a novel canine STS subtype associated with a gene fusion. Moreover, our analyses revealed cross-species conserved transcriptomic and proteomic alterations distinguishing tumour from NT, including pathways linked to extracellular matrix remodelling, immune modulation, and cell proliferation. These data establish the first comprehensive molecular comparison of canine and human FSA and MFS, highlight the translational relevance of canine models, and identify candidate biomarkers for diagnostic refinement and development of targeted therapeutic modalities.

cancer biology↗

bioRxiv2024

The Immune Landscape of Tumor-Associated Macrophage Reprogramming

Tumor-associated macrophages (TAMs) generally acquire immunosuppressive and tumor-promoting phenotypes, which may contribute to tumor resistance to immunotherapy. We previously showed that suppression of microRNA activity through genetic Dicer1 inactivation rewires TAMs transcriptomes and prompts their immunostimulatory activation. This phenotypic switch enhanced recruitment and activation of CD8+ cytotoxic T cells (CTLs) and improved the efficacy of immunotherapy in mouse cancer models. Here, we performed single-cell RNA sequencing of whole tumors grown in either wild-type mice or mice with macrophage-specific Dicer1 deletion. The analysis of multiple cell populations, including several discrete monocyte and macrophage subsets, indicated broad and convergent immunostimulatory programming of the tumor microenvironment, which was dependent on CTL-derived interferon-gamma (IFN{gamma}), in mice with DICER-deficient macrophages. Intriguingly, dynamic inferences on monocyte/macrophage ontogeny and differentiation by pseudotime analysis revealed trajectories associated with progression into cell cycle, monocyte-to-macrophage differentiation, and transition from an immunostimulatory to an immunosuppressive phenotype in tumors with DICER-proficient macrophages. Dicer1 deficiency interfered with this trajectory and stalled TAMs at an intermediate state between immature monocytes and macrophages with T cell-stimulatory capacity, thereby impeding immunosuppressive TAM development. This translated into enhanced response to antiangiogenic immunotherapy in an immunotherapy-resistant model of non-small cell lung cancer. Cycling/M2-like macrophages were conserved in human melanoma and hepatocellular carcinoma and should represent a more promising therapeutic target than the bulk of TAMs.

cancer biology↗

bioRxiv2022

Resistance mechanism to Notch inhibition and combination therapy in human T cell acute lymphoblastic leukemia

Gain-of-function mutations in NOTCH1 are among the most frequent genetic alterations in T cell acute lymphoblastic leukemia (T-ALL), making the Notch signaling pathway a promising therapeutic target for personalized medicine. Yet, a major limitation for long-term success of targeted therapy is relapse due to tumor heterogeneity or acquired resistance. Thus, we performed a genome-wide CRISPR-Cas9 screen to identify prospective resistance mechanisms to pharmacological NOTCH inhibitors and novel targeted combination therapies to efficiently combat T-ALL. Mutational loss of Phosphoinositide-3-Kinase regulatory subunit 1 (PIK3R1) causes resistance to Notch inhibition. PIK3R1 deficiency leads to increased PIK3/Akt signaling which regulates the cell cycle and spliceosome machinery, both at the transcriptional and post-translational level. Moreover, several therapeutic combinations have been identified, where simultaneous targeting of the cyclin-dependent kinases 4 and 6 (CDK4/6) and NOTCH proved to be the most efficacious in T-ALL xenotransplantation models. Key pointsO_LIMutational loss of PIK3R1 induces resistance to NOTCH1 inhibition in T-ALL C_LIO_LIPharmacological Notch inhibition synergizes with CDK4/6 inhibitors in T-ALL C_LI

cancer biology↗

bioRxiv2022

Tumor-educated Gr1+CD11b+ cells instigate breast cancer metastasis by twisting cancer cells plasticity via OSM/IL6-JAK signaling

Cancer cell plasticity contributes to tumor therapy resistance and metastasis formation, which represent the main causes of cancer-related death for most cancers, including breast cancer. The tumor microenvironment drives cancer cell plasticity and metastasis and, thus, unravelling the underlying cues may provide novel effective strategies to manage metastatic disease. Here, we show that stem cell antigen-1 positive (Sca-1+) murine breast cancer cells enriched during tumor progression and metastasis have higher in vitro cancer stem cell-like properties, enhanced in vivo metastatic ability, and initiate primary tumors rich in Gr1highCD11b+Ly6Clow cells. In turn, tumor-educated Gr1+CD11b+ (Tu-Gr1+CD11b+) cells rapidly and transiently convert low metastatic 4T1-Sca-1- cells into highly metastatic 4T1-Sca-1+ cells via secreted OSM and IL6. Moreover, chemotherapy- resistant and highly metastatic 4T1-derived cells maintain high Sca-1+ frequency through cell autonomous IL6 production. Inhibition of OSM, IL6 or JAK suppressed Tu-Gr1+CD11b+-induced Sca-1+ population enrichment in vitro, while JAK inhibition abrogated metastasis of chemotherapy-enriched Sca-1+ cells in vivo. Importantly, Tu-Gr1+CD11b+ cells invoked a gene signature in tumor cells predicting shorter OS and RFS in breast cancer patients. Collectively, our data identified OSM/IL6-JAK as a clinically relevant paracrine/autocrine axis instigating breast cancer cell plasticity triggering metastasis.

cancer biology↗

bioRxiv2020

Transgenic goats producing an improved version of cetuximab in milk

Therapeutic monoclonal antibodies (mAbs) represent one of the most important classes of pharmaceutical proteins to treat human diseases. Most are produced in cultured mammalian cells which is expensive, limiting their availability. Goats, striking a good balance between a relatively short generation time and copious milk yield, present an alternative platform for the cost-effective, flexible, large-scale production of therapeutic mAbs. Here, we focused on cetuximab, a mAb against epidermal growth factor receptor, that is commercially produced under the brand name Erbitux and approved for anti-cancer treatments. We generated several transgenic goat lines that produce cetuximab in their milk. Two lines were selected for detailed characterization. Both showed stable genotypes and cetuximab production levels of up to 10g/L. The mAb could be readily purified and showed improved characteristics compared to Erbitux. The goat-produced cetuximab (gCetuximab) lacked a highly immunogenic epitope that is part of Erbitux. Moreover, it showed enhanced binding to CD16 and increased antibody-dependent cell-dependent cytotoxicity compared to Erbitux. This indicates that these goats produce an improved cetuximab version with the potential for enhanced effectiveness and better safety profile compared to treatments with Erbitux. In addition, our study validates transgenic goats as an excellent platform for large-scale production of therapeutic mAbs.

molecular biology↗