Publications by authors named "George Vassiliou"

Myeloid malignancies carrying somatic DNMT3A mutations (DNMT3Amut) are usually resistant to standard therapy. DNMT3Amut leukemia cells accumulate toxic DNA double strand breaks (DSBs) and collapsed replication forks, rendering them dependent on DNA damage response (DDR). DNA polymerase theta (Polθ), a key element in Polθ-mediated DNA end-joining (TMEJ), is essential for survival and proliferation of DNMT3Amut leukemia cells.

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  • Adult haematopoietic stem cells (HSCs) are essential for creating blood and immune cells, and their function is influenced by signaling pathways like JAK/STAT, specifically through the activation of STAT5.
  • STAT5 deficiency leads to decreased ability for HSCs to self-renew and repopulate various blood lineages, as well as increased differentiation and reduced quiescence, caused by both loss of traditional pSTAT5 signaling and distinct roles played by unphosphorylated STAT5 (uSTAT5).
  • The study suggests that targeting the JAK1/2 pathway with inhibitors like ruxolitinib can improve HSC maintenance and reduce differentiation, potentially providing a strategy for enhancing stem cell function
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Clonal hematopoiesis (CH), the expansion of hematopoietic stem cells and their progeny driven by somatic mutations in leukemia-associated genes, is a common phenomenon that rises in prevalence with advancing age to affect most people older than 70 years. CH remains subclinical in most carriers, but, in a minority, it progresses to a myeloid neoplasm, such as acute myeloid leukemia, myelodysplastic syndrome, or myeloproliferative neoplasm. Over the last decade, advances in our understanding of CH, its molecular landscape, and the risks associated with different driver gene mutations have culminated in recent developments that allow for a more precise estimation of myeloid neoplasia risk in CH carriers.

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  • The DNA damage response is crucial for keeping our genes intact, and its disruption is often linked to cancer development, with PPM1D acting as a key negative regulator.
  • Researchers used CRISPR/Cas9 to find vulnerabilities in cancer cells with mutations in PPM1D, identifying superoxide dismutase-1 (SOD1) as a promising target.
  • The study showed that PPM1D-mutant cells have high levels of reactive oxygen species and struggle with oxidative stress, suggesting that targeting SOD1 could be a new treatment approach for these types of cancers.
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  • People with HIV experience higher mortality rates due to chronic immune activation and age-related health issues.
  • The study examined the link between clonal hematopoiesis (CH), immune markers, and HIV-related factors in a diverse group of 197 PWH, revealing a significant prevalence of CH (27.4%), especially in those with low CD4+ counts and prior opportunistic infections.
  • Results suggest that PWH, particularly those with a history of inflammatory complications, are at increased risk for CH, indicating the need for targeted interventions to reduce this risk.
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While the current approach to precursor hematologic conditions is to "watch and wait," this may change with the development of therapies that are safe and extend survival or delay the onset of symptomatic disease. The goal of future therapies in precursor hematologic conditions is to improve survival and prevent or delay the development of symptomatic disease while maximizing safety. Clinical trial considerations in this field include identifying an appropriate at-risk population, safety assessments, dose selection, primary and secondary trial endpoints including surrogate endpoints, control arms, and quality-of-life metrics, all of which may enable more precise benefit-risk assessment.

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Myeloproliferative neoplasms (MPNs) are chronic cancers characterized by overproduction of mature blood cells. Their causative somatic mutations, for example, JAK2, are common in the population, yet only a minority of carriers develop MPN. Here we show that the inherited polygenic loci that underlie common hematological traits influence JAK2 clonal expansion.

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Acute myeloid leukemia (AML) and myeloid neoplasms develop through acquisition of somatic mutations that confer mutation-specific fitness advantages to hematopoietic stem and progenitor cells. However, our understanding of mutational effects remains limited to the resolution attainable within immunophenotypically and clinically accessible bulk cell populations. To decipher heterogeneous cellular fitness to preleukemic mutational perturbations, we performed single-cell RNA sequencing of eight different mouse models with driver mutations of myeloid malignancies, generating 269,048 single-cell profiles.

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The study of somatic mutations and the associated clonal mosaicism across the human body has transformed our understanding of aging and its links to cancer. In proliferative human tissues, stem cells compete for dominance, and those with an advantage expand clonally to outgrow their peers. In the hematopoietic system, such expansion is termed clonal hematopoiesis (CH).

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  • The DNA damage response is crucial for keeping our genetic material stable and its disruption is often linked to cancer development.
  • PPM1D acts as a key negative regulator of this response, and mutations in this gene have been found in various cancers, making it a potential target for new treatments.
  • Using CRISPR/Cas9 screening, researchers identified SOD1 as a promising target for cells with PPM1D mutations, showing that these cells have higher levels of reactive oxygen species and struggle with oxidative stress, indicating a new cancer therapy approach.
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The myeloid neoplasms encompass acute myeloid leukemia, myelodysplastic syndromes and myeloproliferative neoplasms. Most cases arise from the shared ancestor of clonal hematopoiesis (CH). Here we analyze data from 454,340 UK Biobank participants, of whom 1,808 developed a myeloid neoplasm 0-15 years after recruitment.

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Germ line variants in the DDX41 gene have been linked to myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) development. However, the risks associated with different variants remain unknown, as do the basis of their leukemogenic properties, impact on steady-state hematopoiesis, and links to other cancers. Here, we investigate the frequency and significance of DDX41 variants in 454 792 United Kingdom Biobank (UKB) participants and identify 452 unique nonsynonymous DNA variants in 3538 (1/129) individuals.

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Many hematological diseases are characterized by altered abundance and morphology of blood cells and their progenitors. Myelodysplastic syndromes (MDS), for example, are a group of blood cancers characterised by cytopenias, dysplasia of hematopoietic cells and blast expansion. Examination of peripheral blood slides (PBS) in MDS often reveals changes such as abnormal granulocyte lobulation or granularity and altered red blood cell (RBC) morphology; however, some of these features are shared with conditions such as haematinic deficiency anemias.

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Clonal hematopoiesis (CH) is an age-related condition driven by stem and progenitor cells harboring recurrent mutations linked to myeloid neoplasms. Currently, potential effects on hematopoiesis, stem cell function and regenerative potential under stress conditions are unknown. We performed targeted DNA sequencing of 457 hematopoietic stem cell grafts collected for autologous stem cell transplantation (ASCT) in myeloma patients and correlated our findings with high-dimensional longitudinal clinical and laboratory data (26,510 data points for blood cell counts/serum values in 25 days around transplantation).

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  • - Aged hematopoietic stem cells (HSCs) have reduced self-renewal capacity and a tendency to differentiate into myeloid cells, but the reasons for this change are not fully understood.
  • - Young Aldh2Fancd2 mice's HSCs show an aging-related transcriptomic profile, increased genetic damage, and a preference for myeloid differentiation, alongside heightened activation of the p53 protein in response to damage.
  • - The study suggests that formaldehyde-induced DNA damage affects HSC aging and differentiation, with the activation of the p53 pathway contributing to accelerated aging and myeloid lineage bias in HSCs.
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Nature has evolved intricate machinery to target and degrade RNA, and some of these molecular mechanisms can be adapted for therapeutic use. Small interfering RNAs and RNase H-inducing oligonucleotides have yielded therapeutic agents against diseases that cannot be tackled using protein-centered approaches. Because these therapeutic agents are nucleic acid-based, they have several inherent drawbacks which include poor cellular uptake and stability.

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Resistance to standard and novel therapies remains the main obstacle to cure in acute myeloid leukaemia (AML) and is often driven by metabolic adaptations which are therapeutically actionable. Here we identify inhibition of mannose-6-phosphate isomerase (MPI), the first enzyme in the mannose metabolism pathway, as a sensitizer to both cytarabine and FLT3 inhibitors across multiple AML models. Mechanistically, we identify a connection between mannose metabolism and fatty acid metabolism, that is mediated via preferential activation of the ATF6 arm of the unfolded protein response (UPR).

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  • Scientists studied how changes in gene regulation, which are not directly about the genes themselves, affect cancer in mice.
  • They found that small variations in gene activity can play a big role in how tumors develop and grow.
  • Their research helped identify certain non-coding regions linked to cancer and showed how these changes can lead to serious tumors in specific types of cells.
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HOXA9 is commonly upregulated in acute myeloid leukemia (AML), in which it confers a poor prognosis. Characterizing the protein interactome of endogenous HOXA9 in human AML, we identified a chromatin complex of HOXA9 with the nuclear matrix attachment protein SAFB. SAFB perturbation phenocopied HOXA9 knockout to decrease AML proliferation, increase differentiation and apoptosis in vitro, and prolong survival in vivo.

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Transcriptional variability facilitates stochastic cell diversification and can in turn underpin adaptation to stress or injury. We hypothesize that it may analogously facilitate progression of premalignancy to cancer. To investigate this, we initiated preleukemia in mouse cells with enhanced transcriptional variability due to conditional disruption of the histone lysine acetyltransferase gene .

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