The synergism between DHODH inhibitors and dipyridamole leads to metabolic lethality in acute myeloid leukemia

Dihydroorotate Dehydrogenase (DHODH) is a key enzyme of the de novo pyrimidine biosynthesis, whose inhibition can induce differentiation and apoptosis in acute myeloid leukemia (AML). DHODH inhibitors had shown promising in vitro and in vivo activity on solid tumors, but their effectiveness was not confirmed in clinical trials, probably because cancer cells exploited the pyrimidine salvage pathway to survive. Here, we investigated the antileukemic activity of MEDS433, the DHODH inhibitor developed by our group, against AML. Learning from previous failures, we mimicked human conditions (performing experiments in the presence of physiological uridine plasma levels) and looked for synergic combinations to boost apoptosis, including classical antileukemic drugs and dipyridamole, a blocker of the pyrimidine salvage pathway. MEDS433 induced apoptosis in multiple AML cell lines, not only as a consequence of differentiation, but also directly. Its combination with antileukemic agents further increased the apoptotic rate, but when experiments were performed in the presence of physiological uridine concentrations, results were less impressive. Conversely, the combination of MEDS433 with dipyridamole induced metabolic lethality and differentiation in all AML cell lines; this extraordinary synergism was confirmed on AML primary cells with different genetic backgrounds and was unaffected by physiological uridine concentrations, predicting in human activity

Embedded Fixers, Pragmatic Experimenters, Dedicated Activists: Evaluating Third-Party Labour Market Actors’ Initiatives for Skilled Project-Based Workers in the Gig Economy

Non-standard career paths — in which workers jump from one employment arrangement to another according to the projects they work on — have become more frequent in modern labour markets. The traditional solutions for organizing and managing work relationships and job transitions have become less effective for such workers regarding the risks of precariousness and economic dependence they may experience. Envisioning ways forward requires an appreciation of what was achieved over the past century and an understanding of what is needed to replace and adapt these achievements. Emerging solutions for managing work relationships are provided by a growing range of third-party labour market actors, but the evaluation of their contributions in the literature remains limited. In this article, we build an original theoretical framework to evaluate such contributions according to the kind of services they provide and their respective engagement in institutional innovation. We give examples of solutions developed for skilled workers in two institutional contexts: the Netherlands and Belgium and show how our framework can help distinguish at least three groups of actors that contribute to labour market development in different ways

Intragenic DNA methylation prevents spurious transcription initiation.

In mammals, DNA methylation occurs mainly at CpG dinucleotides. Methylation of the promoter suppresses gene expression, but the functional role of gene-body DNA methylation in highly expressed genes has yet to be clarified. Here we show that, in mouse embryonic stem cells, Dnmt3b-dependent intragenic DNA methylation protects the gene body from spurious RNA polymerase II entry and cryptic transcription initiation. Using different genome-wide approaches, we demonstrate that this Dnmt3b function is dependent on its enzymatic activity and recruitment to the gene body by H3K36me3. Furthermore, the spurious transcripts can either be degraded by the RNA exosome complex or capped, polyadenylated, and delivered to the ribosome to produce aberrant proteins. Elongating RNA polymerase II therefore triggers an epigenetic crosstalk mechanism that involves SetD2, H3K36me3, Dnmt3b and DNA methylation to ensure the fidelity of gene transcription initiation, with implications for intragenic hypomethylation in cance