Biology subjects

Olivier, G.

Publications and source records attributed to Olivier, G..

3 recordsLinked to original sources

bioRxiv2025

DAF-18/PTEN prevents oocyte wastage in spermless C. elegans hermaphrodites by blocking spermatheca neck dilation through RHO-1/RhoA disinhibition

Loss of the Phosphatase and TENsin homolog PTEN drives cancer in humans. In C. elegans hermaphrodites that lack sperm, the PTEN ortholog DAF-18 is required for oocyte quiescence and their proximal accumulation, along with the concomitant homeostatic downregulation of germline stem cell proliferation. As such, spermless daf-18(o) mutants undergo full-scale oogenesis and ovulation in a futile manner, wasting all produced oocytes. When oocyte laying is prevented in these mutants, oocytes hyperaccumulate to form differentiated benign tumors. Here, we show that daf-18 expression in the spermatheca neck myoepithelium is sufficient to induce oocyte arrest and homeostatic downregulation of germline stem cell proliferation in spermless hermaphrodites, altogether prohibiting tumorigenesis. We demonstrate that DAF-18 promotes spermatheca neck contractility through limiting PIP3 levels and AKT activity, preventing the latter from inactivating RHO-1/RhoA by direct phosphorylation at a conserved site. Loss of PTEN may therefore promote benign tumorigenesis in humans through similar cell non-autonomous effects.

genetics↗

bioRxiv2024

Optimized CART Cell Therapy for Metastatic Aggressive Thyroid Cancer

Most thyroid cancer deaths are attributed to a subset of poorly differentiated, metastatic tumors. To improve treatment options for aggressive thyroid cancers, we developed a novel thyroid-stimulating hormone receptor (TSHR)-targeted chimeric antigen receptor T (CART) cell therapy, which demonstrated antigen-specific activation and antitumor efficacy against TSHR+ cell lines in vitro and in vivo. However, de-differentiated thyroid cancers downregulate TSHR. We therefore developed a potent treatment strategy by combining our novel TSHR-CART cells with mitogen-activated protein kinase (MAPK) inhibitors, which redifferentiate thyroid tumors and upregulate TSHR expression. In patient-derived anaplastic thyroid cancer xenografts, combination therapy of TSHR-CART cells and MAPK inhibitors led to increased TSHR expression on the tumor tissue and significantly enhanced antitumor efficacy and prolonged survival compared to TSHR-CART monotherapy. Based on our data, we are launching a phase I clinical trial for TSHR-CART cell therapy alone or in combination with MAPK inhibitors in patients with metastatic thyroid cancers. STATEMENT OF SIGNIFICANCEPoor target selection and antigen escape limit CART cell efficacy in solid tumors. We developed TSHR-CART cells to treat differentiated thyroid cancers but observed TSHR downregulation in dedifferentiated thyroid cancers. We found that MAPK inhibitors restored TSHR expression and sensitized these cancers to TSHR-CART cell therapy.

immunology↗

bioRxiv2021

Comparison of Mucosal and Intramuscular Immunization against SARS-CoV-2 with Replication-Defective and Replicating Single-cycle Adenovirus Vaccines

SARS-CoV-2 enters the body at mucosal surfaces, such as the nose and lungs. These events involve a small number of virions at these mucosal barriers and are therefore a strategic point to stop a COVID-19 infection before it starts. Despite this, most vaccines against COVID-19 are being injected into the muscle where they will not generate the highest levels of mucosal protection. The vaccines that are approved for use in humans are all replication-defective (RD) mRNA, DNA, or adenovirus (Ad) vaccines that do not amplify antigen transgenes. We developed single cycle adenovirus (SC-Ad) vectors that replicate antigen genes up to 10,000-fold in human cells, but that are disabled from producing infectious Ad particles. We show here that SC-Ad expressing the full-length SARS-CoV-2 spike protein produces 100-fold more spike protein than a matched RD-Ad-Spike vector. When Ad-permissive hamsters were immunized with these vaccines by intranasal (IN) or intramuscular (IM) routes, SC-Ad produced significantly stronger antibody responses as compared to RD-Ad against the spike protein that rose over 14 weeks after one immunization. Single IN or IM immunizations generated significant antibody responses in serum and in bronchoalveolar lavages (BALs). IN priming, but not IM priming, generated HLA-restricted CD8 T cell responses in BALs. SC-Ad-Spike generated antibodies that retain binding to spike receptor binding domains (RBDs) with mutations from new viral variants. These data suggest empowering the genomes of gene-based vaccines with the ability to amplify antigen genes can increase potency. This may be particularly advantageous when applying mucosal vaccines to combat mucosal pathogens like SARS-CoV-2. One Sentence SummaryArming adenovirus vaccines with the ability to replicate vaccine antigen genes may increase potency for systemic, or more importantly, mucosal immunization against mucosal pathogens.

immunology↗