bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2020.05.20.107706

Non-canonical cell death by reassortant reovirus

Rodriguez Stewart, R. M.·Raghuram, V.·Berry, J. T. L.·Mainou, B. A.
View original source ↗Export metadata ↓

Abstract

Triple-negative breast cancer (TNBC) constitutes 12% of all breast cancer and is associated with worse prognosis compared to other subtypes of breast cancer. Current therapies are limited to cytotoxic chemotherapy, radiation, and surgery, leaving a need for targeted therapeutics to improve outcomes for TNBC patients. Mammalian orthoreovirus (reovirus) is a nonenveloped, segmented, dsRNA virus in the Reoviridae family. Reovirus preferentially kills transformed cells and is in clinical trials to assess its efficacy against several types of cancer. We previously engineered a reassortant reovirus, r2Reovirus, that infects TNBC cells more efficiently and induces cell death with faster kinetics than parental reoviruses. In this study, we sought to understand the mechanisms by which r2Reovirus induces cell death in TNBC cells. We show that r2Reovirus infection of TNBC cells of a mesenchymal-stem like (MSL) lineage downregulates the MAPK/ERK pathway and induces non-conventional cell death that is caspase dependent, but caspase 3-independent. Infection of different MSL lineage TNBC cells with r2Reovirus results in caspase 3-dependent cell death. We map the enhanced oncolytic properties of r2Reovirus in TNBC to epistatic interactions between the Type 3 Dearing M2 gene segment and Type 1 Lang genes. These findings suggest that the genetic composition of the host cell impacts the mechanism of reovirus-induced cell death in TNBC. Together, our data show that understanding host and virus determinants of cell death can identify novel properties and interactions between host and viral gene products that can be exploited for the development of improved viral oncolytics. ImportanceTriple negative breast cancer (TNBC) is unresponsive to hormone therapies, leaving patients afflicted with this disease with limited treatment options. We previously engineered an oncolytic reovirus (r2Reovirus) with enhanced infective and cytotoxic properties in TNBC cells. However, how r2Reovirus promotes TNBC cell death is not known. In this study, we show that reassortant r2Reovirus can promote non-conventional caspase-dependent but caspase 3-independent cell death and that the mechanism of cell death depends on the genetic composition of the host cell. We also map the enhanced oncolytic properties of r2Reovirus in TNBC to interactions between a Type 3 M2 gene segment and Type 1 genes. Our data show that understanding the interplay between the host cell environment and the genetic composition of oncolytic viruses is crucial for the development of efficacious viral oncolytics.

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Rodriguez Stewart, R. M., Raghuram, V., Berry, J. T. L., Mainou, B. A.. 2020-05-21. Non-canonical cell death by reassortant reovirus. https://doi.org/10.1101/2020.05.20.107706

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile

Clostridioides difficile is a Gram-positive bacterium that causes C. difficile infection (CDI). In healthy adults, it has been proposed that the gut microbiota provides colonization resistance against C. difficile by competition through nutrient limitation and antagonism through secondary bile acid metabolism, the latter of which is mediated by the deconjugation of host-derived bile acids with bacterial bile salt hydrolases (BSH). Recently, BSHs have also shown an ability to reconjugate non-canonical (i.e., not glycine or taurine) amino acids to sterol cores, resulting in novel microbially conjugated bile acids (MCBAs). MCBAs have been associated with the resolution of recurrent CDI, though the mechanism underlying these effects are not well understood. To address this gap, we synthesized 36 MCBAs with nine amino acids (cysteine, isoleucine, leucine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) conjugated to the primary and secondary bile acids found in the human gut (CA, DCA, CDCA, and LCA) and tested their impact on various stages of C. difficiles lifecycle including bacterial outgrowth, membrane integrity, sporulation, and toxin activity. We show that BSH-mediated amidation of bile acid sterol cores can either increase or decrease inhibitory effects on C. difficile in an amino acid-dependent manner. For example, serine MCBAs enhanced C. difficiles ability to grow in otherwise inhibitory bile acid concentrations, increased spore production, and elevated toxin activity. Tryptophan MCBAs increased inhibition. By demonstrating these variable effects, our work clarifies the molecular determinants of MCBA activity and highlights specific MCBAs as promising targets for the development of C. difficile microbial-based therapeutics.

microbiology↗
bioRxiv2026

Magnetic organelle gene clusters enable bacterial growth and ATP homeostasis under oxidizing conditions

Biological organisms can produce magnetic nanoparticles made of magnetite to detect the Earth's magnetic field for orientation. The evolutionary mechanisms that led to the acquisition of this capacity remain unknown. The most ancient organisms known to perform magnetic orientation are magnetotactic bacteria. Under tight genetic control, they produce chains of magnetite nanoparticles in dedicated organelles to allow efficient navigation in aquatic environments containing molecular oxygen. Yet, these bacteria have been proposed to emerge before molecular oxygen became abundant on Earth, at a time when this navigation system could not have served its current function. Here, we show that gene clusters responsible of magnetite formation and organization enable resistance against hydrogen peroxide, a toxic oxygen-derived compound that was produced during the early stages of Earth's oxygenation when iron oxidation consumed molecular oxygen. Characterization of the nanoparticle's oxidation state supported the involvement of magnetite in resistance to hydrogen peroxide-induced oxidative stress. These findings are compatible with an early emergence of magnetotactic bacteria, before natural waters became oxygenated. We propose a conceptual framework to explain the origin of magnetic orientation in bacteria, and offer tools to identify the initiation of Earth's oxygenation in a time-resolved manner.

microbiology↗
bioRxiv2026

Identification and characterization of new P. aeruginosa phages using a surface receptor platform

Bacteriophages are of increasing interest for their potential use as alternatives to antibiotics for treating drug-resistant infections. Phage steering, specifically receptor-based steering, involves use of phages that bias the development of resistance in bacteria towards phenotypes such as reduced fitness. Phage therapy typically involves administering cocktails of phages with different targets to reduce the likelihood of resistance emerging. To ensure effective steering and cocktail design, there is a need to identify the receptors used by phages of interest, and to isolate phages that use diverse receptors. Here we describe a SURFAce Receptor (SURFAR) platform consisting of a set of defined Pseudomonas aeruginosa strains and mutants for rapid characterization of phage receptors. This platform can also be used to enrich for and isolate diverse phages from environmental samples, yielding novel phage genomes from wastewater. Using the SURFAR platform, two new phages were isolated and characterized: Dalewood, which targets both flagella and the conserved LPS outer core, and Bowman, a biofilm targeting phage capable of supressing growth of a subset of carbapenem-resistant clinical isolates. This tool helps to standardize the laborious but important task of phage receptor characterization, with the goal of expanding the known repertoire of P. aeruginosa phage receptors and phages.

microbiology↗