Glioma stem-like cells (GSC) with tumor initiating activity orchestrate the cellular hierarchy in glioblastoma (GBM) and engender therapeutic resistance. Recent work has divided GSC into two subtypes with a mesenchymal (MES) GSC population as the more malignant subtype. In this study, we identify the FOXD1-ALDH1A3 signaling axis as a determinant of the MES GSC phenotype. The transcription factor FOXD1 is expressed predominantly in patient-derived cultures enriched with MES, but not with the proneural (PN) GSC subtype. shRNA-mediated attenuation of FOXD1 in MES GSC ablates their clonogenicity in vitro and in vivo. Mechanistically, FOXD1 regulates the transcriptional activity of ALDH1A3, an established functional marker for MES GSC. Indeed, the functional roles of FOXD1 and ALDH1A3 are likely evolutionally conserved, insofar as RNAi-mediated attenuation of their orthologous genes in Drosophila blocks formation of brain tumors engineered in that species. In clinical specimens of high-grade glioma, the levels of expression of both FOXD1 and ALDH1A3 are inversely correlated with patient prognosis. Lastly, a novel small molecule inhibitor of ALDH we developed, termed GA11, displays potent in vivo efficacy when administered systemically in a murine GSC-derived xenograft model of GBM. Collectively, our findings define a FOXD1-ALDH1A3 pathway in controlling the clonogenic and tumorigenic potential of MES GSC in GBM tumors.

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Creatine monohydrate (Cr), the most diffuse supplement in the sports industry, is receiving greater attention because of its beneficial effects in a wide number of human degenerative diseases and conditions. These effects can be barely explained on the basis of the sole ergogenic role of the Cr/CrP system. Indeed, a wide number of research articles indicate that Cr is capable of exerting multiple, non-energy related, effects on diverse and relevant cellular targets. Among these effects, the antioxidant activity of Cr emerges as an additional mechanism which is likely to play a supportive role in the Cr-cytoprotection paradigm.

An exhaustive description of the molecular recognition mechanism between a ligand and its biological target is of great value because it provides the opportunity for an exogenous control of the related process. Very often this aim can be pursued using high resolution structures of the complex in combination with inexpensive computational protocols such as docking algorithms. Unfortunately, in many other cases a number of factors, like protein flexibility or solvent effects, increase the degree of complexity of ligand/protein interaction and these standard techniques are no longer sufficient to describe the binding event. We have experienced and tested these limits in the present study in which we have developed and revealed the mechanism of binding of a new series of potent inhibitors of Adenosine Deaminase. We have first performed a large number of docking calculations, which unfortunately failed to yield reliable results due to the dynamical character of the enzyme and the complex role of the solvent. Thus, we have stepped up the computational strategy using a protocol based on metadynamics. Our approach has allowed dealing with protein motion and solvation during ligand binding and finally identifying the lowest energy binding modes of the most potent compound of the series, 4-decyl-pyrazolo[1,5-a]pyrimidin-7-one.ADA | well-tempered metadynamics | ligand/protein docking | path collective variables | reweighting algorithm A denosine Deaminase (ADA) regulates the purine metabolism by catalyzing the irreversible hydrolysis of adenosine to inosine and 2′-deoxyadenosine to 2′-deoxyinosine. Thus, this enzyme plays a crucial role in many pathologies such as inflammation, some types of cancer, and others which are strictly connected to the physiological level of these nucleosides (1-5). Despite great efforts in developing ADA inhibitors, only Pentostatin is currently in clinical use (I in Fig. S1) (3). However, recent progress has been reported by Terasaka et al. and by some of us who have developed a new generation of nonnucleoside ADA inhibitors (II, III, and IV in Fig. S1) (6-11). Unfortunately, the understanding at molecular level of the ligand/ADA interaction is hampered by the pronounced ability of the active site to accommodate different inhibitors and by the crucial role played by water molecules during ligand binding. A rational drug design is further complicated by the fact that in response to different inhibitors, ADA can assume either an open or a closed conformation by changing the position of the H3 α-helix (Thr57-Ala73). The open conformation corresponds to the apo-form (PDB ID code 3iar) and is preferred when a nonnucleoside inhibitor is bound (12, 13). In this case, the active site presents a hydrophilic subsite S0 and three hydrophobic subsites F0, F1, and F2 (Fig. 1A) (13). The S0 subsite is defined by the structural gate formed by a β-strand (Leu182-Asp185) and two leucine side chains attached to the H3 α-helix while the F0 site is formed by the hydrophobic side chains of the H3 α-helix. In the op...

pyrimidin-4-one derivatives bearing a phenol or a catechol moiety in position 2 were tested as aldose reductase (ALR2) inhibitors and exhibited activity levels in the micromolar/submicromolar range. Introduction of a hydroxy group in position 6 or 9 gave an enhancement of the inhibitory potency (compare 18, 19, 28, and 29 vs 13 and 14). Lengthening of the 2-side chain to benzyl determined a general reduction in activity. The lack or the methylation of the phenol or catechol hydroxyls gave inactive (10-12, 21, 22, 25-27) or scarcely active (15, 17, 20) compounds, thus demonstrating that the phenol or catechol hydroxyls are involved in the enzyme pharmacophoric recognition. Moreover, all the pyridopyrimidinones displayed significant antioxidant properties, with the best activity shown by the catechol derivatives. The theoretical binding mode of the most active compounds obtained by docking simulations into the ALR2 crystal structure was fully consistent with the structure-activity relationships in the pyrido[1,2-a]pyrimidin-4-one series.