11 research outputs found
Sirtuin functions and modulation: from chemistry to the clinic
Sirtuins are NAD+
-dependent histone deacetylases regulating important metabolic pathways in prokaryotes and
eukaryotes and are involved in many biological processes such as cell survival, senescence, proliferation, apoptosis,
DNA repair, cell metabolism, and caloric restriction. The seven members of this family of enzymes are considered
potential targets for the treatment of human pathologies including neurodegenerative diseases, cardiovascular
diseases, and cancer. Furthermore, recent interest focusing on sirtuin modulators as epigenetic players in the
regulation of fundamental biological pathways has prompted increased efforts to discover new small molecules
able to modify sirtuin activity. Here, we review the role, mechanism of action, and biological function of the
seven sirtuins, as well as their inhibitors and activators
Polymyxins and quinazolines are LSD1/KDM1A inhibitors with unusual structural features
Because of its involvement in the progression of several malignant tumors, the histone lysine-specific demethylase 1 (LSD1) has become a prominent drug target in modern medicinal chemistry research. We report on the discovery of two classes of noncovalent inhibitors displaying unique structural features. The antibiotics polymyxins bind at the entrance of the substrate cleft, where their highly charged cyclic moiety interacts with a cluster of positively charged amino acids. The same site is occupied by quinazoline-based compounds, which were found to inhibit the enzyme through a most peculiar mode because they form a pile of five to seven molecules that obstruct access to the active center. These data significantly indicate unpredictable strategies for the development of epigenetic inhibitors
c-Jun N-terminal kinase activation by nitrobenzoxadiazoles leads to late-stage autophagy inhibition
Background: Nitrobenzoxadiazole derivatives (NBDs), including NBDHEX and the recently developed MC3181, are
promising anticancer agents able to target glutathione transferase and inhibit both its catalytic activity and ability
to sequester TNF-receptor associated factor 2 (TRAF2) and c-Jun N-terminal kinase (JNK). NBDs have been shown
to impair the growth and survival of a broad-spectrum of tumor types, in vitro and in vivo. Herein, we evaluated the
effects of the new compound MC3181 on U-2OS osteosarcoma cells and investigated the impact of both NBDHEX
and MC3181 on autophagy.
Methods: Cell viability was evaluated by sulforhodamine B assay. The dissociation of the TRAF2-GSTP1-1 complex
was detected by proximity ligation assay, while the phospho-activation of JNK was assessed by western blotting. The
effects of NBDs on autophagy were evaluated by GFP-LC3 puncta formation, western blotting for LC3-II and p62, and
LC3 turnover assay in the presence of bafilomycin A1. The role of JNK in the reduction of autophagic flux caused by
NBDs was investigated using JNK1 shRNA-transfected cells. Fluorogenic caspase activity assay and flow cytometric
analysis of DNA content were used to determine the cytotoxic effects of NBDs on JNK1-silenced cells.
Results: Similar to NBDHEX, MC3181 reduced viability and activated TRAF2/JNK signaling in U-2OS cells. Moreover,
NBDs induced the accumulation of autophagic vesicles and LC3-II while reducing both basal and nutritional stressinduced autophagic flux. Furthermore, increased levels of both LC3-II and the autophagy selective substrate p62 were
observed in different tumor cell lines treated with NBDs, the concurrent increase of these markers being consistent
with an impairment of autophagosome clearance. Autophagy inhibition by NBDs required JNK activity: NBDs caused
autophagy inhibition and caspase-3 activation in JNK-positive U-2OS, but no autophagic flux inhibition or caspase-3
activation in JNK-silenced cells.
Conclusions: Our demonstration that NBDs can act as late-phase autophagy inhibitors opens new opportunities to
fully exploit their therapeutic potential. This may not rely solely on their effectiveness in inducing cell cycle arrest and
apoptosis, but also on their ability to weaken the capacity of tumor cells to endure stress conditions via autophagy. In
addition, this study provides evidence that JNK can participate in impairing autophagy
Disruptor of telomeric silencing 1-like (DOT1L): disclosing a new class of non-nucleoside inhibitors by means of ligand-based and structure-based approaches
Chemical inhibition of chromatin-mediated signaling involved proteins is an established strategy to drive expression net-works and alter disease progression. Protein methyltransferases are among the most studied proteins in epigenetics and, in particular, disruptor of telomeric silencing 1-like (DOT1L) lysine methyltransferase plays a key role in MLL-rearranged acute leukemia Selective inhibition of DOT1L is an established attractive strategy to breakdown aberrant H3K79 methylation and thus overexpression of leukemia genes, and leukemogenesis. Although numerous DOT1L inhibitors have been several structural data published no pronounced computational efforts have been yet reported. In these studies a first tentative of multi-stage and LB/SB combined approach is reported in order to maximize the use of available data. Using co-crystallized ligand/DOT1L complexes, predictive 3-D QSAR and COMBINE models were built through a python implementation of previously reported methodologies. The models, validated by either modeled or experimental external test sets, proved to have good predictive abilities. The application of these models to an internal library led to the selection of two unreported compounds that were found able to inhibit DOT1L at micromolar level. To the best of our knowledge this is the first report of quantitative LB and SB DOT1L inhibitors models and their application to disclose new potential epigenetic modulators
Synthesis and structure-activity relationship of new cytotoxic agents targeting human glutathione-S-transferases.
The 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (NBDHEX, 1), a "suicide inhibitor" of the glutathione-S-transferase GSTP1-1, showed pro-apoptotic properties in tumor cells, but in vivo studies were limited by poor bioavailability and high affinity towards GSTM2-2, expressed in many non-cancerous tissues. Here we describe the synthesis and biological characterization of new 1 analogs (2-40), in which the hydroxyhexyl portion at the C4-sulfur atom has been replaced with phenyl-containing moieties as well as substituted alkyl chains. Some of the new compounds displayed 10-100 times increased water-solubility (8, 11, 17, 26-28, 34, 35), and most of them showed higher GSTP1-1 selectivity (2-20, 23-26, 31-33, 35) than 1. The presence of a phenyl ring with polar substituents is in general associated, with some exceptions (23, 24) to low cytotoxicity in osteosarcoma U-2OS cells. Differently, some alkyl derivatives possess cytotoxicity comparable (26, 34, 35) or higher (30, 32) than 1. Among the novel compounds, selected ones (26, 27, 34, and 35) deserve further investigation for their anticancer potential
Synthesis and structure-activity relationship of new cytotoxic agents targeting human glutathione-S-transferases.
The 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (NBDHEX, 1), a "suicide inhibitor" of the glutathione-S-transferase GSTP1-1, showed pro-apoptotic properties in tumor cells, but in vivo studies were limited by poor bioavailability and high affinity towards GSTM2-2, expressed in many non-cancerous tissues. Here we describe the synthesis and biological characterization of new 1 analogs (2-40), in which the hydroxyhexyl portion at the C4-sulfur atom has been replaced with phenyl-containing moieties as well as substituted alkyl chains. Some of the new compounds displayed 10-100 times increased water-solubility (8, 11, 17, 26-28, 34, 35), and most of them showed higher GSTP1-1 selectivity (2-20, 23-26, 31-33, 35) than 1. The presence of a phenyl ring with polar substituents is in general associated, with some exceptions (23, 24) to low cytotoxicity in osteosarcoma U-2OS cells. Differently, some alkyl derivatives possess cytotoxicity comparable (26, 34, 35) or higher (30, 32) than 1. Among the novel compounds, selected ones (26, 27, 34, and 35) deserve further investigation for their anticancer potential
Effect of α-methoxy substitution on the anti-HIV activity of dihydropyrimidin-4(3 H)-ones
Conformational restriction applied to dihydrobenzylpyrimidin-4-(3H)-ones (DABOs) by the intoduction of a methyl group at the α-benzylic position is known to massively improve the anti-HIV-1 activity of these compounds. Here, we report the effects of methoxy substitution at the α-benzylic position in S-, NH-, and N,N-DABOs carrying 2,6-difluoro, 2-chloro-6-fluoro, or 2,6-dichloro substituted benzyl moieties. The various α-methoxy DABO series (12-14) present different SAR at the dihalo benzyl substitution, with the most potent compounds (12d,e and 13c) showing similar (picomolar/nanomolar) anti-HIV-1 potency as the corresponding α-methyl analogues against wt HIV-1, and 10-100-fold increased potency (up to low nanomolar) against clinically relevant K103N, Y181C, Y188L, IRLL98, and K103N+Y181C HIV-1 mutant strains, highlighting the importance of the α-methoxy substitution to provide highly efficient DABOs as "second generation" NNRTIs. HPLC enantioseparation of three of the most potent derivatives (12d, 13c, and 14c) provided single enantiomers with significant enantioselectivity in HIV-1 inhibition. Computational studies allowed to correlate the best antiviral activity with the (R) absolute configuration at the α-methoxy stereogenic center