Biology subjects

LeBleu, V.

Publications and source records attributed to LeBleu, V..

4 recordsLinked to original sources

bioRxiv2023

Engineered immunomodulatory extracellular vesicles derived from epithelial cells acquire capacity for positive and negative T cell co-stimulation in cancer and autoimmunity

Extracellular vesicles (EVs) are generated by all cells and systemic administration of allogenic EVs derived from epithelial and mesenchymal cells have been shown to be safe, despite carrying an array of functional molecules, including thousands of proteins. To address whether epithelial cells derived EVs can be modified to acquire the capacity to induce immune response, we engineered 293T EVs to harbor the immunomodulatory CD80, OX40L and PD-L1 molecules. We demonstrated abundant levels of these proteins on the engineered cells and EVs. Functionally, the engineered EVs efficiently elicit positive and negative co-stimulation in human and murine T cells. In the setting of cancer and auto-immune hepatitis, the engineered EVs modulate T cell functions and alter disease progression. Moreover, OX40L EVs provide additional benefit to anti-CTLA-4 treatment in melanoma-bearing mice. Our work provides evidence that epithelial cell derived EVs can be engineered to induce immune responses with translational potential to modulate T cell functions in distinct pathological settings.

cancer biology↗

bioRxiv2023

Oncogenic KrasG12D specific non-covalent small molecule inhibitor reprograms tumor microenvironment and reverses early precursor lesions and in combination with immunotherapy regresses advanced PDAC in a CD8+ T cells dependent manner

Pancreatic ductal adenocarcinoma (PDAC) is associated with mutations in Kras, a known oncogenic driver of PDAC; and the KRASG12D mutation is present in nearly half of PDAC patients. Recently, a non-covalent small molecule inhibitor (MRTX1133) was identified with specificity to the KrasG12D mutant protein. Here we explore the impact of KrasG12D inhibition by MRTX1133 on advanced PDAC and its influence on the tumor microenvironment. Employing different orthotopic xenograft and syngeneic tumor models, eight different PDXs, and two different autochthonous genetic models, we demonstrate that MRTX1133 reverses early PDAC growth, increases intratumoral CD8+ effector T cells, decreases myeloid infiltration, and reprograms cancer associated fibroblasts. Autochthonous genetic mouse models treated with MRTX1133 leads to regression of both established PanINs and advanced PDAC. Regression of advanced PDAC requires CD8+ T cells and immune checkpoint blockade therapy (iCBT) synergizes with MRTX1133 to eradicate PDAC and prolong overall survival. Mechanistically, inhibition of mutant Kras in advanced PDAC and human patient derived organoids (PDOs) induces Fas expression in cancer cells and facilitates CD8+T cell mediated death. These results demonstrate the efficacy of MRTX1133 in different mouse models of PDAC associated with reprogramming of stromal fibroblasts and a dependency on CD8+ T cell mediated tumor clearance. Collectively, this study provides a rationale for a synergistic combination of MRTX1133 with iCBT in clinical trials.

cancer biology↗

bioRxiv2022

Autophagy is associated with survival and resiliency of fibroblasts in long-term decaying post-mortem parenchymal tissue

Fibroblasts are spindle-shaped mesenchymal cells and an abundantly studied cell type that are easy to culture. Their adaptive response in culture conditions allows for use in many different cell biological experiments, including their utility in generating induced pluripotent stem cells. Despite extensive use of fibroblasts in cell and molecular biology and genetics experiments, fundamental evaluation of their resiliency and survival programs, in comparison with other cell types, is undetermined. Here, we demonstrate that fibroblasts exhibit remarkable survival capacity in post-mortem tissue decaying at room temperature and can be cultured from ear, tail tips, kidney, lung, fetal, and mammary tumor tissue after 12-hours of post-mortem tissue decay. Fibroblasts can be cultured from ear and lung tissue after 24-hours, and from ear after up to 120-hours of post-mortem tissue decay. Gene expression profiling of post-mortem lung tissue fibroblasts compared to fresh tissue cultured fibroblasts suggested a transition to a more quiescent phenotype with activation of nutrient scavenging pathways as evidenced by downregulation of genes associated with DNA replication, ribosomes, cell cycle, and spliceosomes as well as upregulation of genes associated metabolism, autophagy, and lysosomes. Measurement of light chain 3B (LC3B)-I/LC3B-II ratio and lysosomal-associated membrane protein (LAMP)-1 indicate that autophagy is increased in post-mortem fibroblasts, with evidence for potential increase in autolysosomes and senescence program. Our study provides evidence for the ability of normal fibroblasts to overcome extreme stress conditions and offers new insights into cell survival mechanisms and aging, with potential utility in tissue regeneration and repair.

cell biology↗

bioRxiv2017

Multiple antibodies identify Glypican-1 on serum exosomes from patients with pancreatic cancer

Exosomes are man-sized vesicles shed by all cells, including cancer cells. Exosomes can serve as novel liquid biopsies for diagnosis of cancer with potential prognostic value. The exact mechanism/s associated with sorting or enrichment of cellular components into exosomes are still largely unknown. We reported Glypican-1 (GPC1) on the surface of cancer exosomes and provided evidence for the enrichment of GPC1 in exosomes from patients with pancreatic cancer1. Several different laboratories have validated this novel conceptual advance and reproduced the original experiments using multiple antibodies from different sources. These include anti-GPC1 antibodies from ThermoFisher (PA5-28055 and PA-5-24972)1,2, Sigma (SAB270028), Abnova (MAB8351, monoclonal antibodies clone E9E)3, EMD Millipore (MAB2600-monoclonal antibodies)4, SantaCruz5, and R&D Systems (BAF4519)2. This report complements such independent findings and report on the specific detection of Glypican-1 on the exosomes derived from the serum of pancreas cancer patients using multiple antibodies. Additionally, the specificity of the antibodies to GPC1 was determined by western blot and Protein Simple analyses of pancreatic cancer cells and their exosomes. Interestingly, our results highlight a specific enrichment of high molecular weight GPC1 on exosomes, potentially contributed by heparan sulfate and other glycosylation modifications.

cancer biology↗