Publications by authors named "George Kassiotis"

Using joint genomic-transcriptomic analysis of 243 samples, we reveal recurrent patterns of nongenetic evolution in ccRCC not exclusively governed by genetic factors, including T-cell depletion, tumor T-cell receptor coevolution, potential cGAS-STING repression, and increased cell proliferation. These patterns can aid clinical management and guide novel treatment approaches.

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While the key aspects of genetic evolution and their clinical implications in clear cell renal-cell carcinoma (ccRCC) are well-documented, how genetic features co-evolve with the phenotype and tumor microenvironment (TME) remains elusive. Here, through joint genomic-transcriptomic analysis of 243 samples from 79 patients recruited to the TRACERx Renal study, we identify pervasive non-genetic intratumor heterogeneity, with over 40% not attributable to genetic alterations. By integrating tumor transcriptomes and phylogenetic structures, we observe convergent evolution to specific phenotypic traits, including cell proliferation, metabolic reprogramming and overexpression of putative cGAS-STING repressors amid high aneuploidy.

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Background: The emergence of SARS-CoV-2 variants and COVID-19 vaccination have resulted in complex exposure histories. Rapid assessment of the effects of these exposures on neutralising antibodies against SARS-CoV-2 infection is crucial for informing vaccine strategy and epidemic management. We aimed to investigate heterogeneity in individual-level and population-level antibody kinetics to emerging variants by previous SARS-CoV-2 exposure history, to examine implications for real-time estimation, and to examine the effects of vaccine-campaign timing.

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The human genome harbors hundreds of thousands of integrations of ancient retroviruses, amassed over millions of years of evolution. To reduce further amplification in the genome, the host prevents transcription of these now endogenous retroviruses (ERVs) through epigenetic repression and, with evolutionary time, ERVs are incapacitated by accumulating mutations and deletions. However, several members of recently endogenized ERV groups still retain the capacity to produce viral RNA, retroviral proteins, and higher order structures, including virions.

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Cells secrete extracellular vesicles (EVs) and non-vesicular extracellular (nano)particles (NVEPs or ENPs) that may play a role in intercellular communication. Tumor-derived EVs have been proposed to induce immune priming of antigen presenting cells or to be immuno-suppressive agents. We suspect that such disparate functions are due to variable compositions in EV subtypes and ENPs.

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Article Synopsis
  • The first Dark Genome Symposium took place in November 2022 in Boston, organized by biotech companies Rome Therapeutics and Enara Bio to discuss advancements in genetic research and its potential for treating diseases.
  • The event featured welcoming speeches, defining talks by leading academics, and panels that combined perspectives from both academia and industry on various related topics.
  • Richard Young and David Ting concluded the meeting by sharing insights on how the ongoing research into the Dark Genome could positively affect patient outcomes in the future.
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  • * In esophageal adenocarcinoma (EAC) and Barrett's esophagus (BE), researchers found high levels of RTEs in the EAC transcriptome, mainly from genes near RTEs rather than from RTEs themselves.
  • * The study revealed issues with mRNA splicing in EAC, leading to overexpression of specific chimeric transcripts and loss of fully functional mRNAs, which relates to the disease's progression and prognosis, indicating varied molecular features among EAC subtypes.
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  • Increased levels and variety of human endogenous retrovirus (HERV) transcription are found in many cancer types and are associated with disease outcomes, although the mechanisms are not fully understood.
  • The study identified that higher transcription of HERVH in lung squamous cell carcinoma (LUSC) is linked to patient survival and is driven by a CALB1 isoform influenced by HERVH, which begins to express in early preinvasive stages.
  • While calbindin (the protein encoded by CALB1) promotes growth in LUSC, its absence triggers cellular senescence and affects the cancer environment by altering the secretion of factors like CXCL8, leading to increased neutrophil presence and poorer patient prognosis in advanced tumors
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Although all multicellular organisms have germ line-encoded innate receptors to sense pathogen-associated molecular patterns, vertebrates also evolved adaptive immunity based on somatically generated antigen receptors on B and T cells. Because randomly generated antigen receptors may also react with self-antigens, tolerance checkpoints operate to limit but not completely prevent autoimmunity. These two systems are intricately linked, with innate immunity playing an instrumental role in the induction of adaptive antiviral immunity.

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CD4 T cells are typically considered as 'helper' or 'regulatory' populations that support and orchestrate the responses of other lymphocytes. However, they can also develop potent granzyme (Gzm)-mediated cytotoxic activity and CD4 cytotoxic T cells (CTLs) have been amply documented both in humans and in mice, particularly in the context of human chronic infection and cancer. Despite the established description of CD4 CTLs, as well as of the critical cytotoxic activity they exert against MHC class II-expressing targets, their developmental and memory maintenance requirements remain elusive.

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Article Synopsis
  • - Patients with blood cancers have a weakened immune response to the Omicron variants of SARS-CoV-2.
  • - The study shows that Sotrovimab, a monoclonal antibody treatment, continues to effectively neutralize all examined Omicron subvariants.
  • - These findings highlight the need for close monitoring and potential treatment strategies for immunocompromised patients during the pandemic.
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B cells are frequently found in the margins of solid tumours as organized follicles in ectopic lymphoid organs called tertiary lymphoid structures (TLS). Although TLS have been found to correlate with improved patient survival and response to immune checkpoint blockade (ICB), the underlying mechanisms of this association remain elusive. Here we investigate lung-resident B cell responses in patients from the TRACERx 421 (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy) and other lung cancer cohorts, and in a recently established immunogenic mouse model for lung adenocarcinoma.

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Our defenses against infection rely on the ability of the immune system to distinguish invading pathogens from self. This task is exceptionally challenging, if not seemingly impossible, in the case of retroviruses that have integrated almost seamlessly into the host. This review examines the limits of innate and adaptive immune responses elicited by endogenous retroviruses and other retroelements, the targets of immune recognition, and the consequences for host health and disease.

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Mammalian genomes are a battleground for genetic conflict between repetitive elements and KRAB-zinc finger proteins (KZFPs). We asked whether KZFPs can regulate cell fate by using ZFP819, which targets a satellite DNA array, ZP3AR. ZP3AR coats megabase regions of chromosome 7 encompassing genes encoding ZSCAN4, a master transcription factor of totipotency.

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Patients with blood cancer continue to have a greater risk of inadequate immune responses following three COVID-19 vaccine doses and risk of severe COVID-19 disease. In the context of the CAPTURE study (NCT03226886), we report immune responses in 80 patients with blood cancer who received a fourth dose of BNT162b2. We measured neutralizing antibody titers (NAbTs) using a live virus microneutralization assay against wild-type (WT), Delta, and Omicron BA.

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Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a severe acute inflammatory reaction to SARS-CoV-2 infection in children. There is a lack of data describing differential expression of immune genes in MIS-C compared to healthy children or those with other inflammatory conditions and how expression changes over time. In this study, we investigated expression of immune-related genes in South African MIS-C patients and controls.

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Unlabelled: Mutations in oncogenes such as KRAS and EGFR cause a high proportion of lung cancers. Drugs targeting these proteins cause tumor regression but ultimately fail to elicit cures. As a result, there is an intense interest in how to best combine targeted therapies with other treatments, such as immunotherapies.

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Several variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged during the current coronavirus disease 2019 (COVID-19) pandemic. Although antibody cross-reactivity with the spike glycoproteins (S) of diverse coronaviruses, including endemic common cold coronaviruses (HCoVs), has been documented, it remains unclear whether such antibody responses, typically targeting the conserved S2 subunit, contribute to protection when induced by infection or through vaccination. Using a mouse model, we found that prior HCoV-OC43 S-targeted immunity primes neutralizing antibody responses to otherwise subimmunogenic SARS-CoV-2 S exposure and promotes S2-targeting antibody responses.

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Mutations of the ADAR1 gene encoding an RNA deaminase cause severe diseases associated with chronic activation of type I interferon (IFN) responses, including Aicardi-Goutières syndrome and bilateral striatal necrosis. The IFN-inducible p150 isoform of ADAR1 contains a Zα domain that recognizes RNA with an alternative left-handed double-helix structure, termed Z-RNA. Hemizygous ADAR1 mutations in the Zα domain cause type I IFN-mediated pathologies in humans and mice; however, it remains unclear how the interaction of ADAR1 with Z-RNA prevents IFN activation.

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Article Synopsis
  • * Out of those tested, 118 had COVID-19, with 94 showing symptoms and only 2 fatalities, revealing high levels of S1-reactive and neutralizing antibodies against the virus.
  • * Immune responses varied, particularly with hematological cancer patients showing unique challenges but still managing clinical recovery, highlighting the need for more research on immune durability against different SARS-CoV-2 variants.
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