Deliberative bodies have recommended additional protections for persons with dementia included in clinical trials. This survey of experienced dementia researchers revealed that 45 to 64% considered ...that specific ones of these recommendations would increase subject protection, and 40 to 86% considered they would make research less feasible. The real tradeoff between protection and difficulty in conducting research on devastating illnesses needs to be confronted when new regulations in this area are debated.
Persons with impaired decision‐making capacity require special ethical protections during recruitment for and participation in research. To assess how fully basic protections for these persons were ...reported in the literature, the first structured review of a sample of reports of trials including Alzheimer's subjects was performed in 62 journals between January 1992 and December 1998. Neither institutional review board review nor informed consent was mentioned in 28% of the studies. In 48% of the studies, there was no mention of subject involvement in the consent process or that any potential subjects refused or withdrew. Protections may have been offered and simply not reported in the journal articles. The critical importance of these protections would be demonstrated if editors required that authors provide full documentation of ethical protections when submitting an article for review. These might be briefly reported in the articles but be made available electronically to interested readers. Authors could then specify in detail how they conducted their research involving persons with diminished decision‐making capacity.
Acute myeloid leukemia (AML) is induced by the cooperative action of deregulated genes that perturb self-renewal, proliferation, and differentiation. Internal tandem duplications (ITDs) in the FLT3 ...receptor tyrosine kinase are common mutations in AML, confer poor prognosis, and stimulate myeloproliferation. AML patient samples with FLT3-ITD express high levels of RUNX1, a transcription factor with known tumor-suppressor function. In this study, to understand this paradox, we investigated the impact of RUNX1 and FLT3-ITD coexpression. FLT3-ITD directly impacts on RUNX1 activity, whereby up-regulated and phosphorylated RUNX1 cooperates with FLT3-ITD to induce AML. Inactivating RUNX1 in tumors releases the differentiation block and down-regulates genes controlling ribosome biogenesis. We identified
as a direct target of RUNX1 and FLT3-ITD stimulation and confirmed high
expression in FLT3-ITD AMLs. HHEX could replace RUNX1 in cooperating with FLT3-ITD to induce AML. These results establish and elucidate the unanticipated oncogenic function of RUNX1 in AML. We predict that blocking RUNX1 activity will greatly enhance current therapeutic approaches using FLT3 inhibitors.
Disrupting mutations of the RUNX1 gene are found in 10% of patients with myelodysplasia (MDS) and 30% of patients with acute myeloid leukemia (AML). Previous studies have revealed an increase in ...hematopoietic stem cells (HSCs) and multipotent progenitor (MPP) cells in conditional Runx1-knockout (KO) mice, but the molecular mechanism is unresolved. We investigated the myeloid progenitor (MP) compartment in KO mice, arguing that disruptions at the HSC/MPP level may be amplified in downstream cells. We demonstrate that the MP compartment is increased by more than fivefold in Runx1 KO mice, with a prominent skewing toward megakaryocyte (Meg) progenitors. Runx1-deficient granulocyte-macrophage progenitors are characterized by increased cloning capacity, impaired development into mature cells, and HSC and Meg transcription signatures. An HSC/MPP subpopulation expressing Meg markers was also increased in Runx1-deficient mice. Rescue experiments coupled with transcriptome analysis and Runx1 DNA-binding assays demonstrated that granulocytic/monocytic (G/M) commitment is marked by Runx1 suppression of genes encoding adherence and motility proteins (Tek, Jam3, Plxnc1, Pcdh7, and Selp) that support HSC–Meg interactions with the BM niche. In vitro assays confirmed that enforced Tek expression in HSCs/MPPs increases Meg output. Interestingly, besides this key repressor function of Runx1 to control lineage decisions and cell numbers in progenitors, our study also revealed a critical activating function in erythroblast differentiation, in addition to its known importance in Meg and G/M maturation. Thus both repressor and activator functions of Runx1 at multiple hematopoietic stages and lineages likely contribute to the tumor suppressor activity in MDS and AML.
•Runx1 is a key determinant of megakaryocyte cell-fate decisions in multipotent progenitors.•Runx1 downregulates cell-adhesion factors that promote residency of stem cells and megakaryocytes in their bone marrow niche.
The Runx1 transcription factor is among the most frequently mutated genes in acute myeloid leukemia (AML). In addition to the generation of the RUNX1-RUNX1T1 fusion protein in patients with the ...translocation (8;21), circa 15% of patients with a normal karyotype harbor missense mutations or frame-shift mutations in the RUNX1 gene, in most cases resulting in either a highly compromised protein lacking DNA-binding activity or a null allele. Recent studies have demonstrated that AML transformation normally occurs at the level of the granulocyte-monocyte-progenitor (GMP), thus we sought to dissect the role of Runx1 at this critical stage of myeloid differentiation by examining the hematopoietic progenitor compartment in conditional Runx1 knockout (KO) mice. Earlier studies have demonstrated increased cell numbers in the stem cell compartment in these mice, but a rigorous assessment of myeloid progenitors has not been performed. Our analysis showed that loss of Runx1 resulted in increased levels of all myeloid progenitors, with a 2.2-fold increase in the absolute GMP numbers. Furthermore, Runx1-deficient GMPs gave rise to 40% more colonies than controls, demonstrating increased self-renewal activity within this population. Notably, in addition to being larger, Runx1-deficient colonies did not exhibit the typical structure of GM colonies, which reflects the differentiation status of the cells composing the colonies. Indeed, retarded or impaired differentiation of Runx1-defcient cells was demonstrated by analysis of cell morphology and cell surface markers, with little or no mature forms observed in colonies cultured for 7 to 10 days. Notably, no significant shift to either the G or M lineages was observed in vitro or in vivo.
To identify Runx1 target genes that impact at the level of the GMP, expression analysis of Runx1 wild-type and KO GMPs was performed. In addition, the transcriptome of primary KO GMPs genetically engineered to conditionally re-express RUNX1 in vivo was determined before or after Runx1 induction. A total of 36 reciprocally regulated genes were identified using stringent criteria to assess expression levels and fold-induction. Notably, many of the Runx1 target genes encode adhesion factors important for retaining HSPC in the stem cell niche, and which are normally down-regulated during differentiation. These genes were up-regulated in Runx1-deficient GMPs and down-regulated after Runx1 induction. Genome wide DNA-binding analysis established Runx1 binding to regulatory regions of target genes and furthermore revealed cooperative binding of Runx1 with several other TFs implicated in complex networks regulating self-renewal and differentiation of early hematopoietic progenitors. In vitro adhesion assays confirmed that loss of Runx1 resulted in increased adhesion to hematopoietic stromal cells.
In summary, we conclude that Runx1 has at least two critical functions in normal myeloid development. In the early stem cell and progenitor compartment, Runx1 represses genes that mediate adhesion to the stem cell niche, thereby facilitating the differentiation program at the expense of self-renewal. On the other hand, during myeloid maturation, Runx1 augments both G and M developmental programs, presumably by facilitating up-regulation of critical granulocytic and monocytic genes. We predict that this former function is of critical importance during leukemogenesis, in which reduced levels of functional Runx1 increases the number of myeloid progenitors with self-renewal potential, which are critical targets of secondary genetic mutations during the clonal evolution of the leukemic clone.
No relevant conflicts of interest to declare.
Primary Myelofibrosis (PMF) is a Myeloproliferating Neoplasm (MPN) of hematopoietic stem cell origin, characterized by expansion of aberrant myeloid progenitors in the chronic phase that can lead to ...bone marrow fibrosis development and/or osteosclerosis. In 20-25% of PMF cases transformation to acute myeloid leukemia (AML) is observed. Identification of multiple molecular lesions suggests complex clone dynamics that indicates exceeding sub-clone dominance as PMF progresses. Our aim is to determine the HSC hierarchy orchestrating initiation and development of PMF.
In our previous studies we reported a CD133+ HSC population in PMF peripheral blood that represents the aberrant long-term stem cell fraction responsible for PMF reproduction of chronic and acute phases in vivo. Molecular analysis of PMF xenografts indicates sustenance of genetically different HSC clones exhibiting variation in both their engraftment potential and reproduction of PMF parameters in the first mouse model of the disease.
To further characterize the succession of molecular lesions determining HSC clone propagation we performed targeted exon sequencing of PMF HSC from 100 PMF patients for 54 genes. Mutations in the epigenetic regulators ASXL1 and EZH2 were detected in 38% and 15% of PMF patients respectively. HSC clonal evolution was determined by single cell molecular and phenotypic analysis in vitro and graft analysis in vivo.
Mutations detected in the epigenetic regulators ASXL1 and EZH2 represent founding molecular lesions at the top of PMF HSC hierarchy. ASXL1 mutations precede and are connected with sustenance of clonal hematopoiesis without any significant influence on the HSC differentiation potential. EZH2 mutations are connected with impaired erythropoiesis in vitro and anemia, high engraftment and expansion of pre-leukemic clones in vivo. Occurrence of JAK2 and CALR mutations in the background of mutated epigenetic regulator genes is connected with expansion of HSC subclones and reproduction of chronic phase PMF as atypical myelopoiesis, splenomegaly and induction of fibrosis.
Our results indicate genetic heterogeneity of PMF neoplastic HSC is comprised of three different mutational clusters. Mutations in epigenetic regulator genes (Group 1) precede and shape the epigenetic landscape conferring genetic instability to sustain the expansion of pre-leukemic clones (Group 3 mutations). JAK2 and CALR mutations (Group 2) occur later on and are connected with aberrant myelopoiesis of chronic phase disease. HSC clonal dynamics reflect genotype related phenotypes as determinants of chronic and acute phases of PMF.
No relevant conflicts of interest to declare.
With great sadness, we learned of the passing of Professor Dr. med. Rolf-Dietmar Neth, the founder of the Wilsede meeting, on March 17, 2020, aged 93 in his home town Buchholz near Wilsede/Lüneburger ...Heide. Rolf Neth was born 6.10.1926. After the 2nd World War, Rolf Neth studied Medicine from 1949 to 1955 at the University of Göttingen. Then he was at the Max-Planck-Institut für Experimentelle Medizin (University Göttingen, 1956-1957), and promoted his skills in clinical and experimental hematology in St. George Hospital (1958-1959) in Hamburg.
From 1960, his activity was connected with the pediatric clinics of Hamburg University where he became a Professor at the Children Hospital in 1972. From 1970 to 1980, Rolf Neth was occupied implementing new laboratory diagnostic approaches in the booming field of clinical hematology. Blood cancer treatment was developed, due to novel drugs invented to combat leukemic cells and rescue the small patients which 10-20 years ago had only zero chance to survive. Histo- and immunochemical diagnostics became routine tests for evaluation of clinical forms of leukemias and efficiency of their therapy. Since 1982, he coordinated laboratory hematology at the Department of Clinical Chemistry, University Hamburg, until retirement in 1992.
Along with contribution to clinical laboratory science, Professor Neth, over 1973 to 2002, arranged a series of famous Wilsede Meetings "Modern Trends in Human Leukemia" dedicated to leukemia research and treatment. Rolf Neth and Robert Gallo decided time and topic of the meeting, and Rolf Neth proposed a place, i.e., a lonely village in the Luneburg heath, not far from his home. Hence, Leukemia and Viruses was selected as a specific topic for a meeting in Germany, because it was timely for convergence between clinical medicine and cancer biology.
Rolf Neth organized the first Wilsede meetings himself for more than 20 years, until he passed these efforts to Wolfram Ostertag and Axel Zander. In the late 1990s, Carol Stocking and Boris Fehse took on this responsibility. Over last years, Wilsede meetings were arranged by Nicolaus Kröger and Boris Fehse. And as long as his health permitted, Rolf Neth came along to see how his baby was doing. He participated and assisted at any stage of the next meeting. We are thankful to have had the privilege of knowing and cooperating with Rolf Neth and to cherish his legacy by keeping the Wilsede tradition alive. He was married with Hanne-Lore Cohrs, 8.11. 1958, survived by his wife of 62 years Hanne-Lore, and four sons and several grandchildren.
Prion diseases are fatal neurodegenerative disorders. An important step in disease pathophysiology is the conversion of cellular prion protein (PrP
C
) to disease-associated misfolded conformers (PrP
...Sc
). These misfolded PrP variants are a common component of prion infectivity and are detectable in diseased brain and lymphoreticular organs such as spleen. In the latter, PrP
Sc
is thought to replicate mainly in follicular dendritic cells within spleen follicles. Although the presence of PrP
Sc
is a hallmark for prion disease and serves as a main diagnostic criterion, in certain instances the amount of PrP
Sc
does not correlate well with neurotoxicity or prion infectivity. Therefore, it has been proposed that prions might be a mixture of different conformers and aggregates with differing properties. This study investigated the impact of disruption of spleen architecture by neoplasia on the abundance of different PrP species in spleens of prion-infected mice. Although follicular integrity was completely disturbed, titres of prion infectivity in neoplastic spleens were not significantly altered, yet no protease-resistant PrP
Sc
was detectable. Instead, unique protease-sensitive prion species could be detected in neoplastic spleens. These results indicate the dissociation of PrP
Sc
and prion infectivity and showed the presence of non-PrP
Sc
PrP species in spleen with divergent biochemical properties that become apparent after tissue architecture disruption.
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