23 research outputs found
Pharmacologic inhibition of the Menin-MLL interaction blocks progression of MLL leukemia in vivo
Chromosomal translocations affecting mixed lineage leukemia gene (MLL) result in acute leukemias resistant to therapy. The leukemogenic activity of MLL fusion proteins is dependent on their interaction with menin, providing basis for therapeutic intervention. Here we report the development of highly potent and orally bioavailable small-molecule inhibitors of the menin-MLL interaction, MI-463 and MI-503, and show their profound effects in MLL leukemia cells and substantial survival benefit in mouse models of MLL leukemia. Finally, we demonstrate the efficacy of these compounds in primary samples derived from MLL leukemia patients. Overall, we demonstrate that pharmacologic inhibition of the menin-MLL interaction represents an effective treatment for MLL leukemias in vivo and provide advanced molecular scaffold for clinical lead identification
Discovery of first-in-class inhibitors of ASH1L histone methyltransferase with anti-leukemic activity
ASH1L histone methyltransferase plays a crucial role in the pathogenesis of different diseases, including acute leukemia. While ASH1L represents an attractive drug target, developing ASH1L inhibitors is challenging, as the catalytic SET domain adapts an inactive conformation with autoinhibitory loop blocking the access to the active site. Here, by applying fragment-based screening followed by medicinal chemistry and a structure-based design, we developed first-in-class small molecule inhibitors of the ASH1L SET domain. The crystal structures of ASH1L-inhibitor complexes reveal compound binding to the autoinhibitory loop region in the SET domain. When tested in MLL leukemia models, our lead compound, AS-99, blocks cell proliferation, induces apoptosis and differentiation, downregulates MLL fusion target genes, and reduces the leukemia burden in vivo. This work validates the ASH1L SET domain as a druggable target and provides a chemical probe to further study the biological functions of ASH1L as well as to develop therapeutic agents
Synthesis and Biological Applications of Heterocyclic and Organofluorine Compounds
Heterocyclic and organofluorine compounds play a crucial role in human life, since they have exceptional biological activities. The traditional methods for their synthesis usually do not comply contemporary safety and environmental regulations. The goal of this work was to design new, safer and environmentally benign methods for synthesis of heterocyclic and organofluorine compounds for biological applications.
Initially work was focused on using solid acid catalysis for the synthesis of heterocyclic compounds. A new method was developed for the diastereoselective preparation of cis-aziridines from imines and ethyl diazoacetate using K-10 as catalyst. The reaction provided the products in excellent yields and exclusive selectivity. The same K-10 catalyst with combination of microwave irradiation was applied for the cyclocondensation of alkylhydrazines to alk-3-yn-1-ones leading to 1,3,5-trisubstituted pyrazoles in excellent yields. In both reactions the catalyst could be recycled and used in subsequent reactions without significant loss of activity.
Then we developed environmentally benign methods for the synthesis of organofluorine compounds. We designed a new method for synthesis of aryl-3,3,3-trifluoropropenes by Wittig olefination of ylides with trifluoroacetaldehyde ethyl hemiacetal. We also developed the first asymmetric synthetic preparation of trifluoro-1-(indol-3-yl)ethanols by an enantioselective hydroquinine-catalyzed reaction from indoles and inexpensive trifluoroacetaldehyde methyl hemiacetal. Trifluoro-1-(indol-3-yl)ethanols were produced in excellent yields and good enantioselectivities.
In the next two projects we worked on the biological applications of heterocyclic and organofluorine compounds. A highly diastereoselective microwave-assisted multicomponent synthesis of azabicyclo[2.2.2]octan-5-ones by a silicotungstic acid-catalyzed aza-Diels-Alder cyclization has been developed. The focus was on using a green catalyst and alternative source of energy. Preliminary assays were performed to determine the activity of the products in acetylcholinesterase enzyme as well as in amyloid beta self-assembly.
Finally the molecular docking of a broad variety of pyrrole, indole and pyrazole-based fructose 1,6-bisphosphatase inhibitors has been carried out and the potential of these compounds has been evaluated. 5 heterocyclic and organofluorine compounds were selected, synthesized and tested in the inhibition of the FBPase enzyme. The best inhibitor showed an IC50 value that was better than that of AMP, the natural inhibitor of FBPase, by over two orders of magnitude
Enantioselective Friedel-Crafts Reaction of Indoles with Trifluoroacetaldehyde Catalyzed by Cinchona Alkaloids
The first direct asymmetric synthetic preparation of trifluoro-1-(indol-3-yl)ethanols (TFIEs) is described by an enantioselective organocatalytic method from indoles and inexpensive trifluoroacetaldehyde methyl hemiacetal. The reaction is catalyzed by hydroquinine to produce TFIEs in an almost quantitative yield and with enantioselectivities up to 75% at room temperature. The enantioselectivity is strongly dependent on the concentration of substrates and catalyst due to the competitive noncatalyzed reaction. Chirality, 2011. © 2011 Wiley-Liss, Inc
Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentus complex) from the Eastern Ukraine
Background: Hybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid - P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes. Results: In order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)(n)-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes. Conclusions: The constructed cytological maps of lampbrush chromosomes of P. ridibundus and P. lessonae provide basis to define the type of genome transmitted within individual oocytes of P. esculentus females with different ploidy and from various population systems
Cytological maps of lampbrush chromosomes of European water frogs (Pelophylax esculentus complex) from the Eastern Ukraine
Background: Hybridogenesis (hemiclonal inheritance) is a kind of clonal reproduction in which hybrids between parental species are reproduced by crossing with one of the parental species. European water frogs (Pelophylax esculentus complex) represent an appropriate model for studying interspecies hybridization, processes of hemiclonal inheritance and polyploidization. P. esculentus complex consists of two parental species, P. ridibundus (the lake frog) and P. lessonae (the pool frog), and their hybridogenetic hybrid - P. esculentus (the edible frog). Parental and hybrid frogs can reproduce syntopically and form hemiclonal population systems. For studying mechanisms underlying the maintenance of water frog population systems it is required to characterize the karyotypes transmitted in gametes of parental and different hybrid animals of both sexes. Results: In order to obtain an instrument for characterization of oocyte karyotypes in hybrid female frogs, we constructed cytological maps of lampbrush chromosomes from oocytes of both parental species originating in Eastern Ukraine. We further identified certain molecular components of chromosomal marker structures and mapped coilin-rich spheres and granules, chromosome associated nucleoli and special loops accumulating splicing factors. We recorded the dissimilarities between P. ridibundus and P. lessonae lampbrush chromosomes in the length of orthologous chromosomes, number and location of marker structures and interstitial (TTAGGG)(n)-repeat sites as well as activity of nucleolus organizer. Satellite repeat RrS1 was mapped in centromere regions of lampbrush chromosomes of the both species. Additionally, we discovered transcripts of RrS1 repeat in oocytes of P. ridibundus and P. lessonae. Moreover, G-rich transcripts of telomere repeat were revealed in association with terminal regions of P. ridibundus and P. lessonae lampbrush chromosomes. Conclusions: The constructed cytological maps of lampbrush chromosomes of P. ridibundus and P. lessonae provide basis to define the type of genome transmitted within individual oocytes of P. esculentus females with different ploidy and from various population systems
Inhibition of CDC25B Phosphatase Through Disruption of Protein–Protein Interaction
CDC25
phosphatases are key cell cycle regulators and represent
very attractive but challenging targets for anticancer drug discovery.
Here, we explored whether fragment-based screening represents a valid
approach to identify inhibitors of CDC25B. This resulted in identification
of 2-fluoro-4-hydroxybenzonitrile, which directly binds to the catalytic
domain of CDC25B. Interestingly, NMR data and the crystal structure
demonstrate that this compound binds to the pocket distant from the
active site and adjacent to the protein–protein interaction
interface with CDK2/Cyclin A substrate. Furthermore, we developed
a more potent analogue that disrupts CDC25B interaction with CDK2/Cyclin
A and inhibits dephosphorylation of CDK2. Based on these studies,
we provide a proof of concept that targeting CDC25 phosphatases by
inhibiting their protein–protein interactions with CDK2/Cyclin
A substrate represents a novel, viable opportunity to target this
important class of enzymes
Rational Design of Orthogonal Multipolar Interactions with Fluorine in Protein–Ligand Complexes
Multipolar interactions involving
fluorine and the protein backbone
have been frequently observed in protein–ligand complexes.
Such fluorine–backbone interactions may substantially contribute
to the high affinity of small molecule inhibitors. Here we found that
introduction of trifluoromethyl groups into two different sites in
the thienopyrimidine class of menin–MLL inhibitors considerably
improved their inhibitory activity. In both cases, trifluoromethyl
groups are engaged in short interactions with the backbone of menin.
In order to understand the effect of fluorine, we synthesized a series
of analogues by systematically changing the number of fluorine atoms,
and we determined high-resolution crystal structures of the complexes
with menin. We found that introduction of fluorine at favorable geometry
for interactions with backbone carbonyls may improve the activity
of menin–MLL inhibitors as much as 5- to 10-fold. In order
to facilitate the design of multipolar fluorine–backbone interactions
in protein–ligand complexes, we developed a computational algorithm
named FMAP, which calculates fluorophilic sites in proximity to the
protein backbone. We demonstrated that FMAP could be used to rationalize
improvement in the activity of known protein inhibitors upon introduction
of fluorine. Furthermore, FMAP may also represent a valuable tool
for designing new fluorine substitutions and support ligand optimization
in drug discovery projects. Analysis of the menin–MLL inhibitor
complexes revealed that the backbone in secondary structures is particularly
accessible to the interactions with fluorine. Considering that secondary
structure elements are frequently exposed at protein interfaces, we
postulate that multipolar fluorine–backbone interactions may
represent a particularly attractive approach to improve inhibitors
of protein–protein interactions