GRASP55 Regulates Sorting and Maturation of the Lysosomal Enzyme β-Hexosaminidase A.

The Golgi apparatus plays a crucial role in the delivery of lysosomal enzymes. Golgi Reassembly Stacking Proteins, GRASP55 and GRASP65, are vital for maintaining Golgi structure and function. GRASP55 depletion results in the missorting and secretion of the lysosomal enzyme Cathepsin D (Xiang .

Plasticity and structural alterations of mitochondria and sarcoplasmic organelles in muscles of mice deficient in α-dystrobrevin, a component of the dystrophin-glycoprotein complex.

The dystrophin-glycoprotein complex (DGC) plays a crucial role in maintaining the structural integrity of the plasma membrane and the neuromuscular junction. In this study, we investigated the impact of the deficiency of α-dystrobrevin (αdbn), a component of the DGC, on the homeostasis of intracellular organelles, specifically mitochondria and the sarcoplasmic reticulum (SR). In αdbn deficient muscles, we observed a significant increase in the membrane-bound ATP synthase complex levels, a marker for mitochondria in oxidative muscle fiber types compared to wild-type.

Hereditary Alpha Tryptasemia: Validation of a Single-Well Multiplex Digital Droplet PCR Assay in a Cohort of Symptomatic Patients.

Background: Hereditary alpha tryptasemia (HαT) has significant prevalence and potential morbidity in the general population. However, it remains largely undiagnosed in routine clinical diagnostics due to low availability of efficient assessment methods. To address this issue, we developed a reliable and efficient single-well multiplex digital droplet PCR assay.

The nonessential amino acid cysteine is required to prevent ferroptosis in acute myeloid leukemia.

Cysteine is a nonessential amino acid required for protein synthesis, the generation of the antioxidant glutathione, and for synthesizing the nonproteinogenic amino acid taurine. Here, we highlight the broad sensitivity of leukemic stem and progenitor cells to cysteine depletion. By CRISPR/CRISPR-associated protein 9-mediated knockout of cystathionine-γ-lyase, the cystathionine-to-cysteine converting enzyme, and by metabolite supplementation studies upstream of cysteine, we functionally prove that cysteine is not synthesized from methionine in acute myeloid leukemia (AML) cells.

Increased Histological Tumor Pigmentation in Uveal Melanoma Is Related to Eye Color and Loss of Chromosome 3/BAP1.

Purpose: Heavy pigmentation is known to be a prognostic risk factor in uveal melanoma (UM). We analyzed whether genetic tumor parameters were associated with tumor pigmentation and whether pigmentation should be included in prognostic tests.

Design: Retrospective comparison of clinical, histopathological, and genetic features and survival in UM with different pigmentation.

Zebrafish Patient-Derived Xenograft Model as a Preclinical Platform for Uveal Melanoma Drug Discovery.

Uveal melanoma (UM) is a rare malignant cancer of the eye, with up to 50% of patients dying from metastasis, for which no effective treatment is available. Due to the rarity of the disease, there is a great need to harness the limited material available from primary tumors and metastases for advanced research and preclinical drug screening. We established a platform to isolate, preserve, and transiently recover viable tissues, followed by the generation of spheroid cultures derived from primary UM.

Dietary methionine starvation impairs acute myeloid leukemia progression.

Targeting altered tumor cell metabolism might provide an attractive opportunity for patients with acute myeloid leukemia (AML). An amino acid dropout screen on primary leukemic stem cells and progenitor populations revealed a number of amino acid dependencies, of which methionine was one of the strongest. By using various metabolite rescue experiments, nuclear magnetic resonance-based metabolite quantifications and 13C-tracing, polysomal profiling, and chromatin immunoprecipitation sequencing, we identified that methionine is used predominantly for protein translation and to provide methyl groups to histones via S-adenosylmethionine for epigenetic marking.

Inhibition of the succinyl dehydrogenase complex in acute myeloid leukemia leads to a lactate-fuelled respiratory metabolic vulnerability.

Metabolic programs can differ substantially across genetically distinct subtypes of acute myeloid leukemia (AML). These programs are not static entities but can change swiftly as a consequence of extracellular changes or in response to pathway-inhibiting drugs. Here, we uncover that AML patients with FLT3 internal tandem duplications (FLT3-ITD) are characterized by a high expression of succinate-CoA ligases and high activity of mitochondrial electron transport chain (ETC) complex II, thereby driving high mitochondrial respiration activity linked to the Krebs cycle.

Presence of mutant p53 increases stem cell frequency and is associated with reduced binding to classic TP53 binding sites in cell lines and primary AMLs.

With an overall 5%-10% incidence rate in acute myeloid leukemia (AML), the occurrence of TP53 mutations is low compared with that in solid tumors. However, when focusing on high-risk groups including secondary AML (sAML) and therapy-related AMLs, the frequency of mutations reaches up to 35%. Mutations may include loss of heterozygosity (LOH) or deletion of the 17p allele, but are mostly missense substitutions that are located in the DNA-binding domain.

The Glycolytic Gatekeeper PDK1 defines different metabolic states between genetically distinct subtypes of human acute myeloid leukemia.

Acute myeloid leukemia remains difficult to treat due to strong genetic heterogeneity between and within individual patients. Here, we show that Pyruvate dehydrogenase kinase 1 (PDK1) acts as a targetable determinant of different metabolic states in acute myeloid leukemia (AML). PDK1 AMLs are OXPHOS-driven, are enriched for leukemic granulocyte-monocyte progenitor (L-GMP) signatures, and are associated with FLT3-ITD and NPM1cyt mutations.

Chromosome 3 and 8q Aberrations in Uveal Melanoma Show Greater Impact on Survival in Patients with Light Iris versus Dark Iris Color.

Purpose: Individuals with gray, blue, or green eyes have a higher chance of developing uveal melanoma (UM) than those with brown eyes. We wondered whether iris pigmentation might be related not only to predisposition to UM but also to its behavior; therefore, we compared the clinical, histopathologic, and genetic characteristics of UM between eyes with different colors.

Design: We determined iris color in a large cohort of patients enucleated for UM.

and Its Ligands Show Increased Expression in High-Risk Uveal Melanoma.

Uveal melanoma (UM) is a rare ocular malignancy which originates in the uveal tract, and often gives rise to metastases. Potential targets for immune checkpoint inhibition are lymphocyte-activation gene 3 (LAG3) and its ligands. We set out to analyse the distribution of these molecules in UM.

Expression of HDACs 1, 3 and 8 Is Upregulated in the Presence of Infiltrating Lymphocytes in Uveal Melanoma.

In Uveal Melanoma (UM), an inflammatory phenotype is strongly associated with the development of metastases and with chromosome 3/BAP1 expression loss. As an increased expression of several Histone Deacetylases (HDACs) was associated with loss of chromosome 3, this suggested that HDAC expression might also be related to inflammation. We analyzed HDAC expression and the presence of leukocytes by mRNA expression in two sets of UM (Leiden and TCGA) and determined the T lymphocyte fraction through ddPCR.

MiRNAs Correlate with HLA Expression in Uveal Melanoma: Both Up- and Downregulation Are Related to Monosomy 3.

MicroRNAs are known to play a role in the regulation of inflammation. As a high HLA Class I expression is associated with a bad prognosis in UM, we set out to determine whether any miRNAs were related to a high HLA Class I expression and inflammation. We also determined whether such miRNAs were related to the UM's genetic status.

In Uveal Melanoma, Angiopoietin-2 but Not Angiopoietin-1 Is Increased in High-Risk Tumors, Providing a Potential Druggable Target.

Uveal melanoma (UM) metastasize haematogeneously, and tumor blood vessel density is an important prognostic factor. We hypothesized that proangiogenic factors such as angiopoietin-1 (ANG-1) and angiopoietin-2 (ANG-2), two targetable cytokines, might play a role in tumor development and metastatic behavior. mRNA levels of ANG-1 and ANG-2 were determined in 64 tumors using an Illumina HT-12 v4 mRNA chip and compared to clinical, pathologic, and genetic tumor parameters.

Five Decades of Enucleations for Uveal Melanoma in One Center: More Tumors with High Risk Factors, No Improvement in Survival over Time.

Background: In order to improve medical care for uveal melanoma (UM) patients, we need to monitor disease and survival to guide our research efforts. We analyzed the data of UM patients who underwent an enucleation at the Leiden University Medical Center over the last five decades and investigated trends in patient and tumor characteristics and survival.

Methods: Data were collected from charts and pathology reports from all patients who underwent an enucleation for UM between 1973 and 2019 ( = 1,212), of which 1,066 were primary enucleations; data were analyzed according to five time periods: 1973-1979 ( = 209), 1980-1989 ( = 148), 1990-1999 ( = 174), 2000-2009 ( = 280), and 2010-2019 ( = 401).

HDAC Inhibition Increases HLA Class I Expression in Uveal Melanoma.

The treatment of uveal melanoma (UM) metastases or adjuvant treatment may imply immunological approaches or chemotherapy. It is to date unknown how epigenetic modifiers affect the expression of immunologically relevant targets, such as the HLA Class I antigens, in UM. We investigated the expression of HDACs and the histone methyl transferase EZH2 in a set of 64 UMs, using an Illumina HT12V4 array, and determined whether a histone deacetylase (HDAC) inhibitor and EZH2 inhibitor modified the expression of HLA Class I on three UM cell lines.

Iris Colour and the Risk of Developing Uveal Melanoma.

Uveal melanoma (UM) is a global disease which especially occurs in elderly people. Its incidence varies widely between populations, with the highest incidence among Caucasians, and a South-to-North increase in Europe. As northern Europeans often have blond hair and light eyes, we wondered whether iris colour may be a predisposing factor for UM and if so, why.

mutated acute myeloid leukemia in a child with metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria.

D-2-hydroxyglutaric aciduria (D-2-HGA) is a rare metabolic disorder characterized by developmental delay, hypotonia, and bi-allelic mutations in D-2-hydroxyglutarate dehydrogenase or a single gain-of-function mutation in isocitrate dehydrogenase 2 Metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria (MC-HGA) is a type of D-2-HGA that has been previously reported in ten patients (OMIM 614875), three of whom had somatic mosaicism for R132 variants in isocitrate dehydrogenase 1 (). We describe a 3-year-old boy with MC-HGA who subsequently developed acute myeloid leukemia (AML) and was found to have an R132C mutation in a leukemic bone marrow sample. Further testing revealed presence of somatic mosaicism for R132C variant, suggesting an association of in inducing myeloid leukemogenesis.

HIF1/2-exerted control over glycolytic gene expression is not functionally relevant for glycolysis in human leukemic stem/progenitor cells.

Background: Hypoxia-inducible factors (HIF)1 and 2 are transcription factors that regulate the homeostatic response to low oxygen conditions. Since data related to the importance of HIF1 and 2 in hematopoietic stem and progenitors is conflicting, we investigated the chromatin binding profiles of HIF1 and HIF2 and linked that to transcriptional networks and the cellular metabolic state.

Methods: Genome-wide ChIPseq and ChIP-PCR experiments were performed to identify HIF1 and HIF2 binding sites in human acute myeloid leukemia (AML) cells and healthy CD34 hematopoietic stem/progenitor cells.

Aqueous Humor Biomarkers Identify Three Prognostic Groups in Uveal Melanoma.

Purpose: To investigate whether we can identify different patterns of inflammation in the aqueous humor of a uveal melanoma (UM)-containing eye, and whether these are related to prognosis.

Methods: Ninety samples of aqueous humor from UM-containing eyes were analyzed using a high-throughput multiplex immunoassay that enables simultaneous analysis of 92 predefined protein biomarkers. Cytokine expression was compared to clinical and histopathological characteristics.

Soluble HLA in the Aqueous Humour of Uveal Melanoma Is Associated with Unfavourable Tumour Characteristics.

A high HLA expression in uveal melanoma (UM) is part of the prognostically unfavorable inflammatory phenotype. We wondered whether the presence of soluble HLA (sHLA) in the aqueous humour is associated with clinical, histopathological or genetic tumour characteristics, and represents tumour HLA expression and intratumoural inflammation. Aqueous humour from 108 UM patients was analysed for the presence of sHLA, using a Luminex assay specific for HLA Class I.