Biology subjects

Randall, R.

Publications and source records attributed to Randall, R..

3 recordsLinked to original sources

bioRxiv2022

Transformation of Human Mesenchymal Stem Cells into High-Grade Sarcomas by YAP1 and K-RAS Reflects the Undifferentiated Pleomorphic Sarcoma-Myxofibrosarcoma Disease Spectrum

High-grade complex karyotype sarcomas are a heterogeneous group of more than seventy tumors that vary in histology, clinical course, and patient demographics. Despite these clear differences, these high-grade sarcomas are treated similarly with a uniformly high metastatic rate. Pre-clinical models that allow for rigorous comparisons of distinct human sarcoma subtypes would advance insights into the relationships between sarcomas and inform therapeutic decisions. We describe the robust transformation of human mesenchymal stem cells into multiple subtypes of high-grade sarcoma. Using a pooled genetic screening approach, we identified key drivers and potential modifiers of transformation. YAP1 and KRAS were validated as drivers of two distinct sarcoma subtypes, undifferentiated pleomorphic sarcoma (UPS) and myxofibrosarcoma (MFS), respectively. In addition, the pathology of tumors driven by CDK4 and PIK3CA reflected leiomyosarcoma (LMS) and osteosarcoma (OS) indicating that further iterations of this model could result in additional sarcoma subtypes. Histologically and phenotypically these tumors reflect human sarcomas including the pathognomonic complex karyotype. In addition, CDK4 and PIK3CA driven tumors demonstrated endogenous YAP1 amplification which is seen across a subset of human tumors. While all tumors overlapped transcriptionally with the TCGA sarcoma data, further analysis confirmed that YAP1 and KRAS tumors recapitulate the UPS and MFS subtypes. Co-analysis of TCGA and model tumors support that these sarcoma subtypes lie along a spectrum of disease and adds guidance for further transcriptome-based refinement of sarcoma subtyping. Within complex karyotype sarcomas, there are multiple genetic changes but identifying those that are clinically relevant has been challenging. Comparing differentially expressed genes in YAP1 and KRAS tumors to human UPS and MFS identified the enrichment of oxidative phosphorylation pathways in both YAP1 tumors and UPS. Treatment of a panel of sarcoma cell lines with the combination of an oxidative phosphorylation inhibitor and Hippo pathway inhibitor led to a significant impairment in growth identifying new therapeutic targets. A subset of human UPS tumors showed an even greater enrichment in these pathways indicating this model can be used to identify clinically relevant subtypes. This model can be used to begin to understand pathways and mechanisms driving human sarcoma development, the relationship between sarcoma subtypes and to identify and test new therapeutic vulnerabilities for this aggressive and heterogeneous disease. Statement of SignificanceWe have created the first model to study the development, growth, and metastasis of multiple human sarcoma subtypes. This system can be used as a platform to investigate sarcoma biology and identify new therapeutic targets across a heterogeneous disease.

cancer biology↗

bioRxiv2018

Mini viral RNAs act as innate immune agonists during influenza virus infection

Influenza A virus infection usually causes a mild to moderately severe respiratory disease in humans. However, infection with the 1918 H1N1 pandemic or highly pathogenic avian influenza viruses (HPAIV) of the H5N1 subtype, can lead to viral pneumonia, systemic disease and death. The molecular processes that determine the outcome of influenza virus infection are multifactorial and involve a complex interplay between host, viral, and bacterial factors1. However, it is generally accepted that a strong innate immune dysregulation known as cytokine storm contributes to the pathology of pandemic and avian influenza virus infections2-4. The RNA sensor Retinoic acid-inducible gene I (RIG-I) plays an important role in sensing viral infection and initiating a signalling cascade that leads to interferon (IFN) expression5. Here we show that short aberrant RNAs (mini viral RNAs; mvRNAs), produced by the viral RNA polymerase during the replication of the viral RNA genome, bind and activate the intracellular pathogen sensor RIG-I, and lead to the expression of interferon-{beta}. We find that erroneous polymerase activity, dysregulation of viral RNA replication, or the presence of avian-specific amino acids underlie mvRNA generation and cytokine expression in mammalian cells and propose an intramolecular copy-choice mechanism for mvRNA generation. By deep-sequencing RNA samples from lungs of ferrets infected with influenza viruses we show that mvRNAs are generated during infection of animal models. We propose that mvRNAs act as main agonists of RIG-I during influenza virus infection and the ability of influenza virus strains to generate mvRNAs should be considered when assessing their virulence potential.

microbiology↗

bioRxiv2018

Strange Stable Replicators Generated From Mumps Virus cDNA Clones

In reverse genetic experiments we have isolated recombinant mumps viruses (rMuV) based on a recent clinical isolate that carry large numbers of mutations clustered in small parts of their genome and which are not caused by biased hyper-mutation. In two separate experiments we obtained such rMuV: one virus had 19 mutations in the V/P region of the genome; the other, which also contained an extra transcription unit encoding green fluorescent protein (EGFP), had 32 mutations in the N gene. These specific constellations of mutations have not been observed in naturally occurring MuV isolates. The vast majority of the mutations (48/51) are synonymous.\n\nOn passage in Vero cells and human B-LCL cells, a B lymphocyte-like cell Line, these mutations appear stable as no reversal occurs to the original consensus sequences, though mutations in other genes occur and change in frequency during passage. Defective Interfering RNAs accumulate in passage in Vero cells but not in B-LCL cells. Interestingly, in all passaged samples the level of variation in the EGFP gene is the same as in the viral genes, though it is unlikely that this gene is under any functionality constraint. The stability in repeated high multiplicity passage indicates that the constellation of mutations is placing the virus on a fitness peak from which it cannot escape. What mechanism gave rise to these mutant viruses and their stability remain open questions of interest to a wider field than mumps reverse genetics alone.

microbiology↗