Biology subjects

Barbie, D. A.

Publications and source records attributed to Barbie, D. A..

3 recordsLinked to original sources

bioRxiv2022

STING activation promotes robust immune response and tumor regression in glioblastoma models

Immunotherapy has had a tremendous impact on cancer treatment in the past decade, with hitherto unseen responses at advanced and metastatic stages of the disease. However, the aggressive brain tumor glioblastoma (GBM) is highly immunosuppressive and remains largely refractory to current immunotherapeutic approaches. The cGAS-STING cytoplasmic double stranded DNA (dsDNA) sensing pathway has emerged as a next-generation immunotherapy target with potent local immune stimulatory properties. Here, we investigated the status of the STING pathway in GBM and the modulation of the brain tumor microenvironment (TME) with the STING agonist ADU-S100. Our data reveal the presence of STING in human GBM specimens, where it stains strongly in the tumor vasculature. We show that human GBM explants can respond to STING agonist treatment by secretion of inflammatory cytokines. In murine GBM models, we show a profound shift in the tumor immune landscape after STING agonist treatment, with massive infiltration of the tumor-bearing hemisphere with innate immune cells including inflammatory macrophages, neutrophils and NK populations. Treatment of established murine intracranial GL261 and CT-2A tumors by biodegradable ADU-S100-loaded intracranial implants demonstrated a significant increase in survival in both models and long-term survival with immune memory in GL261. Responses to treatment were abolished by NK cell depletion. This study reveals therapeutic potential and deep remodeling of the TME by STING activation in GBM and warrants the further examination of STING agonists alone or in combination with other immunotherapies such as cancer vaccines, CAR T cells, NK therapies or immune checkpoint blockade. Significance statementModulation of the immune microenvironment is critical for immunosuppressive and therapy refractory tumors like glioblastoma. Activation of the STING pathway deeply remodels the brain tumor environment and attracts innate immune cells and natural killer cell populations, producing a robust antitumor effect with long-term immune memory. We further show that human glioblastoma tissue can respond to the therapy and lay the foundations for combined intracranial immunotherapies by using crosslinked biodegradable brain implants.

cancer biology↗

bioRxiv2021

Regulation of Neuroendocrine Plasticity by the RNA-Binding Protein ZFP36L1

Some small cell lung cancers (SCLCs) are highly sensitive to inhibitors of the histone demethylase LSD1. LSD1 inhibitors are thought to induce their anti-proliferative effects by blocking neuroendocrine differentiation, but the mechanisms by which LSD1 controls the SCLC neuroendocrine phenotype are not well understood. To identify genes required for LSD1 inhibitor sensitivity in SCLC, we performed a positive selection genome-wide CRISPR/Cas9 loss of function screen and found that ZFP36L1, an mRNA-binding protein that destabilizes mRNAs, is required for LSD1 inhibitor sensitivity. LSD1 binds and represses ZFP36L1 and upon LSD1 inhibition, ZFP36L1 expression is restored, which is sufficient to block the SCLC neuroendocrine differentiation phenotype and induce a non-neuroendocrine "inflammatory" phenotype. Mechanistically, ZFP36L1 binds and destabilizes SOX2 and INSM1 mRNAs, two transcription factors that are required for SCLC neuroendocrine differentiation. This work identifies ZFP36L1 as an LSD1 target gene that controls the SCLC neuroendocrine phenotype and demonstrates that modulating mRNA stability of lineage transcription factors controls neuroendocrine to non-neuroendocrine plasticity.

cancer biology↗

bioRxiv2021

Engineering the Immune Adaptor Protein STING as a Biologic

Activation of the stimulator of interferon genes (STING) pathway through cyclic dinucleotides (CDNs) has been explored extensively as potent vaccine adjuvants against infectious diseases as well as to increase tumor immunogenicity towards cancer immunotherapy in solid tumors. Over the last decade, a myriad of synthetic vehicles, including liposomes, polymers, and other nanoparticle platforms, have been developed to improve the bioavailability and therapeutic efficacy of STING agonists in preclinical mouse models. In comparison to synthetic materials, protein-based carriers represent an attractive delivery platform owing to their biocompatibility, amenability to genetic engineering, and intrinsic capacity to form well-defined structures. In the present work, we have engineered the immune adaptor STING as a protein-based delivery system for efficient encapsulation and intracellular delivery of CDNs. Through genetic fusion with a protein transduction domain, the recombinant STING can spontaneously penetrate cells to markedly enhance the delivery of CDNs in a mouse vaccination model and a syngeneic mouse melanoma model. Moreover, motivated by recent findings that certain tumor cells can evade immune surveillance via loss of STING expression, we further unveiled that our STING platform can serve as a functional vehicle to restore the STING signaling in a panel of lung and melanoma cell lines with impaired STING expression. Taken together, our STING-based protein delivery platform may offer a unique direction towards targeting STING-silenced tumors as well as augmenting the efficacy of STING-based vaccine adjuvants.

bioengineering↗