Upregulation of MYC is a hallmark of cancer, wherein MYC drives oncogenic gene expression and elevates total RNA synthesis across cancer cell transcriptomes. Although this transcriptional anabolism fuels cancer growth and survival, the consequences and metabolic stresses induced by excess cellular RNA are poorly understood. Herein, we discover that RNA degradation and downstream ribonucleotide catabolism is a novel mechanism of MYC-induced cancer cell death. Combining genetics and metabolomics, we find that MYC increases RNA decay through the cytoplasmic exosome, resulting in the accumulation of cytotoxic RNA catabolites and reactive oxygen species. Notably, tumor-derived exosome mutations abrogate MYC-induced cell death, suggesting excess RNA decay may be toxic to human cancers. In agreement, purine salvage acts as a compensatory pathway that mitigates MYC-induced ribonucleotide catabolism, and inhibitors of purine salvage impair MYC+ tumor progression. Together, these data suggest that MYC-induced RNA decay is an oncogenic stress that can be exploited therapeutically. Significance: MYC is the most common oncogenic driver of poor-prognosis cancers but has been recalcitrant to therapeutic inhibition. We discovered a new vulnerability in MYC+ cancer where MYC induces cell death through excess RNA decay. Therapeutics that exacerbate downstream ribonucleotide catabolism provide a therapeutically tractable approach to TNBC (Triple-negative Breast Cancer) and other MYC-driven cancers.

• MeSH
• lidé MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory prsu * metabolismus   genetika   patologie   MeSH
• protoonkogenní proteiny c-myc * metabolismus   genetika   MeSH
• regulace genové exprese u nádorů MeSH
• ribonukleotidy * farmakologie   MeSH
• stabilita RNA * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Inhibition of hypoxanthine-guanine-xanthine phosphoribosyltransferase activity decreases the pool of 6-oxo and 6-amino purine nucleoside monophosphates required for DNA and RNA synthesis, resulting in a reduction in cell growth. Therefore, inhibitors of this enzyme have potential to control infections, caused by Plasmodium falciparum and Plasmodium vivax, Trypanosoma brucei, Mycobacterium tuberculosis, and Helicobacter pylori. Five compounds synthesized here that contain a purine base covalently linked by a prolinol group to one or two phosphonate groups have Ki values ranging from 3 nM to >10 μM, depending on the structure of the inhibitor and the biological origin of the enzyme. X-ray crystal structures show that, on binding, these prolinol-containing inhibitors stimulated the movement of active site loops in the enzyme. Against TBr in cell culture, a prodrug exhibited an EC50 of 10 μM. Thus, these compounds are excellent candidates for further development as drug leads against infectious diseases as well as being potential anticancer agents.

• MeSH
• inhibitory enzymů * farmakologie   chemie   chemická syntéza   MeSH
• katalytická doména MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• pentosyltransferasy * antagonisté a inhibitory   metabolismus   MeSH
• racionální návrh léčiv * MeSH
• Trypanosoma brucei brucei účinky léků   enzymologie   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Pathogens such as Plasmodium and Trypanosoma spp. are unable to synthesize purine nucleobases. They rely on the salvage of these purines and their nucleosides from the host cell to synthesize the purine nucleotides required for DNA/RNA production. The key enzymes in this pathway are purine phosphoribosyltransferases (PRTs). Here, we synthesized 16 novel acyclic nucleoside phosphonates, 12 with a chiral center at C-2', and eight bearing a second chiral center at C-6'. Of these, bisphosphonate (S,S)-48 is the most potent inhibitor of the Plasmodium falciparum and P. vivax 6-oxopurine PRTs and the most potent inhibitor of two Trypanosoma brucei (Tbr) 6-oxopurine PRTs yet discovered, with Ki values as low as 2 nM. Crystal structures of (S,S)-48 in complex with human and Tbr 6-oxopurine PRTs show that the inhibitor binds to the enzymes in different conformations, providing an explanation for its potency and selectivity (i.e., 35-fold in favor of the parasite enzymes).

• MeSH
• antimalarika * farmakologie   MeSH
• inhibitory enzymů chemie   farmakologie   MeSH
• lidé MeSH
• nukleosidy chemie   farmakologie   MeSH
• organofosfonáty * chemie   farmakologie   MeSH
• paraziti * MeSH
• pentosyltransferasy metabolismus   MeSH
• Plasmodium falciparum MeSH
• purinony MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Helicobacter pylori (Hp) is a human pathogen that lives in the gastric mucosa of approximately 50% of the world's population causing gastritis, peptic ulcers, and gastric cancer. An increase in resistance to current drugs has sparked the search for new Hp drug targets and therapeutics. One target is the disruption of nucleic acid production, which can be achieved by impeding the synthesis of 6-oxopurine nucleoside monophosphates, the precursors of DNA and RNA. These metabolites are synthesized by Hp xanthine-guanine-hypoxanthine phosphoribosyltransferase (XGHPRT). Here, nucleoside phosphonates have been evaluated, which inhibit the activity of this enzyme with Ki values as low as 200 nM. The prodrugs of these compounds arrest the growth of Hp at a concentration of 50 μM in cell-based assays. The kinetic properties of HpXGHPRT have been determined together with its X-ray crystal structure in the absence and presence of 9-[(N-3-phosphonopropyl)-aminomethyl-9-deazahypoxanthine, providing a basis for new antibiotic development.

• MeSH
• antibakteriální látky chemie   metabolismus   farmakologie   terapeutické užití   MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• gastrointestinální nemoci farmakoterapie   mikrobiologie   patologie   MeSH
• Helicobacter pylori účinky léků   enzymologie   MeSH
• hypoxanthinfosforibosyltransferasa chemie   metabolismus   MeSH
• hypoxanthiny chemie   metabolismus   farmakologie   terapeutické užití   MeSH
• infekce vyvolané Helicobacter pylori farmakoterapie   patologie   MeSH
• kinetika MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• organofosfonáty chemie   metabolismus   farmakologie   terapeutické užití   MeSH
• pentosyltransferasy chemie   metabolismus   MeSH
• prekurzory léčiv chemie   metabolismus   farmakologie   terapeutické užití   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• simulace molekulární dynamiky MeSH
• vazebná místa MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Parasites of the Plasmodium genus are unable to produce purine nucleotides de novo and depend completely on the salvage pathway. This fact makes plasmodial hypoxanthine-guanine-(xanthine) phosphoribosyltransferase [HG(X)PRT] a valuable target for development of antimalarial agents. A series of nucleotide analogues was designed, synthesized and evaluated as potential inhibitors of Plasmodium falciparum HGXPRT, P. vivax HGPRT and human HGPRT. These novel nucleoside phosphonates have a pyrrolidine, piperidine or piperazine ring incorporated into the linker connecting the purine base to a phosphonate group(s) and exhibited a broad range of Ki values between 0.15 and 72 μM. The corresponding phosphoramidate prodrugs, able to cross cell membranes, have been synthesized and evaluated in a P. falciparum infected human erythrocyte assay. Of the eight prodrugs evaluated seven exhibited in vitro antimalarial activity with IC50 values within the range of 2.5-12.1 μM. The bis-phosphoramidate prodrug 13a with a mean (SD) IC50 of 2.5 ± 0.7 μM against the chloroquine-resistant P. falciparum W2 strain exhibited low cytotoxicity in the human hepatocellular liver carcinoma (HepG2) and normal human dermal fibroblasts (NHDF) cell lines at a concentration of 100 μM suggesting good selectivity for further structure-activity relationship investigations.

• MeSH
• antimalarika chemická syntéza   metabolismus   farmakologie   MeSH
• buněčné linie MeSH
• erytrocyty cytologie   metabolismus   parazitologie   MeSH
• inhibitory enzymů chemie   metabolismus   MeSH
• léková rezistence účinky léků   MeSH
• lidé MeSH
• nukleotidy chemie   metabolismus   MeSH
• pentosyltransferasy antagonisté a inhibitory   metabolismus   MeSH
• piperazin chemie   MeSH
• piperidiny chemie   MeSH
• Plasmodium falciparum účinky léků   enzymologie   MeSH
• Plasmodium vivax enzymologie   MeSH
• preklinické hodnocení léčiv MeSH
• prekurzory léčiv chemická syntéza   chemie   metabolismus   farmakologie   MeSH
• protozoální proteiny antagonisté a inhibitory   metabolismus   MeSH
• pyrrolidiny chemie   MeSH
• viabilita buněk účinky léků   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) is a recognized target for antimalarial chemotherapeutics. It synthesises all of the 6-oxopurine nucleoside monophosphates, IMP, GMP and XMP needed by the malarial parasite, Plasmodium falciparum (Pf). PfHGXPRT is also indirectly responsible for the synthesis of the adenosine monophosphate, AMP. The acyclic nucleoside phosphonates (ANPs) are a class of PfHGXPRT inhibitors. Prodrugs of these compounds are able to arrest the growth of Pf in cell culture. In the search for new inhibitors of PfHGXPRT, a series of sulfur containing ANPs (thia-ANPs) has been designed and synthesized. These compounds are based on the structure of 2-(phosphonoethoxy)ethylguanine (PEEG) and PEEHx which consist of a purine base (i.e. guanine or hypoxanthine) linked to a phosphonate group by five atoms i.e. four carbons and one oxygen. Here, PEEG and PEEHx were modified by substituting a sulfide, sulfoxide or a sulfone bridge for the oxygen atom in the linker. The effect of these substitutions on the Ki values for human HGPRT and PfHGXPRT was investigated and showed that most of the thia-ANPs distinctively favour PfHGXPRT. For example, the thia-analogue of PEEHx has a Ki value of 0.2 μM for PfHGXPRT, a value 25-fold lower than for the human counterpart. Prodrugs of these compounds have IC50 values in the 4-6 μM range in antimalarial cell-based assays, making them attractive compounds for further development as antimalarial drug leads.

• MeSH
• antimalarika chemická syntéza   farmakologie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• nukleosidy chemická syntéza   farmakologie   MeSH
• organofosfonáty chemická syntéza   farmakologie   MeSH
• oxidace-redukce MeSH
• pentosyltransferasy antagonisté a inhibitory   MeSH
• Plasmodium falciparum účinky léků   enzymologie   MeSH
• prekurzory léčiv chemická syntéza   farmakologie   MeSH
• sulfidy chemie   MeSH
• sulfony chemie   MeSH
• sulfoxidy chemie   MeSH
• termodynamika MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The 6-oxopurine phosphoribosyltransferases (PRTs) are drug targets for the treatment of parasitic diseases. This is due to the fact that parasites are auxotrophic for the 6-oxopurine bases relying on salvage enzymes for the synthesis of their 6-oxopurine nucleoside monophosphates. In Trypanosoma brucei, the parasite that is the aetiological agent for sleeping sickness, there are three 6-oxopurine PRT isoforms. Two are specific for hypoxanthine and guanine, whilst the third, characterized here, uses all three naturally occurring bases with similar efficiency. Here, we have determined crystal structures for TbrHGXPRT in complex with GMP, XMP and IMP to investigate the structural basis for substrate specificity. The results show that Y201 and E208, not commonly observed within the purine binding pocket of 6-oxopurine PRTs, contribute to the versatility of this enzyme. The structures further show that a nearby water can act as an adaptor to facilitate the binding of XMP and GMP. When GMP binds, a water can accept a proton from the 2-amino group but when XMP binds, the equivalent water can donate its proton to the 2-oxo group. However, when IMP is bound, no water molecule is observed at that location. DATABASE: Coordinates and structure factors were submitted to the Protein Data Bank and have accession codes of 6MXB, 6MXC, 6MXD and 6MXG for the TbrHGXPRT.XMP complex, TbrHGXPRT.GMP complex, TbrHGXPRT.IMP complex, and TbrHGPRT.XMP complex, respectively.

• MeSH
• inosinmonofosfát chemie   metabolismus   MeSH
• konformace proteinů MeSH
• kyselina 5'-guanylová chemie   metabolismus   MeSH
• pentosyltransferasy chemie   metabolismus   MeSH
• ribonukleotidy chemie   metabolismus   MeSH
• sekvence aminokyselin MeSH
• substrátová specifita MeSH
• Trypanosoma brucei brucei enzymologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) are the foremost causative agents of malaria. Due to the development of resistance to current antimalarial medications, new drugs for this parasitic disease need to be discovered. The activity of hypoxanthine-guanine-[xanthine]-phosphoribosyltransferase, HG[X]PRT, is reported to be essential for the growth of both of these parasites, making it an excellent target for antimalarial drug discovery. Here, we have used rational structure-based methods to design an inhibitor, [3R,4R]-4-guanin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine, of PvHGPRT and PfHGXPRT that has Ki values of 8 and 7 nM, respectively, for these two enzymes. The crystal structure of PvHGPRT in complex with this compound has been determined to 2.85 Å resolution. The corresponding complex with human HGPRT was also obtained to allow a direct comparison of the binding modes of this compound with the two enzymes. The tetra-(ethyl l-phenylalanine) tetraamide prodrug of this compound was synthesized, and it has an IC50 of 11.7 ± 3.2 μM against Pf lines grown in culture and a CC50 in human A549 cell lines of 102 ± 11 μM, thus giving it a ∼10-fold selectivity index.

• MeSH
• antimalarika chemie   farmakologie   MeSH
• bisfosfonáty chemie   farmakologie   MeSH
• hypoxanthinfosforibosyltransferasa antagonisté a inhibitory   chemie   metabolismus   MeSH
• katalytická doména MeSH
• konformace proteinů MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• molekulární modely MeSH
• pentosyltransferasy antagonisté a inhibitory   chemie   metabolismus   MeSH
• Plasmodium vivax enzymologie   MeSH
• proteiny z Escherichia coli chemie   MeSH
• racionální návrh léčiv MeSH
• techniky syntetické chemie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Therapeutic treatment of tuberculosis (TB) is becoming increasingly problematic due to the emergence of drug resistant Mycobacterium tuberculosis (Mt). Thus, new targets for anti-TB drug discovery need to be identified to combat and eradicate this disease. One such target is hypoxanthine-guanine phosphoribosyltransferase (HGPRT) which synthesises the 6-oxopurine nucleoside monophosphates essential for DNA/RNA production. [3R,4R]-4-Hypoxanthin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine and [3R,4R]-4-guanin-9-yl-3-((S)-2-hydroxy-2-phosphonoethyl)oxy-1-N-(phosphonopropionyl)pyrrolidine (compound 6) are the most potent inhibitors of MtHGPRT yet discovered having Ki values of 60 nM. The crystal structure of the MtHGPRT.6 complex was obtained and compared with that of human HGPRT in complex with the same inhibitor. These structures provide explanations for the 60-fold difference in the inhibition constants between these two enzymes and a foundation for the design of next generation inhibitors. In addition, crystal structures of MtHGPRT in complex with two pyrrolidine nucleoside phosphosphonate inhibitors plus pyrophosphate provide insights into the final stage of the catalytic reaction. As the first step in ascertaining if such compounds have the potential to be developed as anti-TB therapeutics, the tetra-(ethyl L-phenylalanine) tetraamide prodrug of 6 was tested in cell based assays. This compound arrested the growth of virulent Mt not only in its replicating phase (IC50 of 14 μΜ) but also in its latent phase (IC50 of 29 μΜ). Furthermore, it arrested the growth of Mt in infected macrophages (MIC50 of 85 μΜ) and has a low cytotoxicity in mammalian cells (CC50 of 132 ± 20 μM). These inhibitors are therefore viewed as forerunners of new anti-TB chemotherapeutics.

• MeSH
• antituberkulotika chemická syntéza   chemie   farmakologie   MeSH
• bisfosfonáty chemie   farmakologie   MeSH
• hypoxanthinfosforibosyltransferasa antagonisté a inhibitory   metabolismus   MeSH
• inhibitory enzymů chemická syntéza   chemie   farmakologie   MeSH
• kultivované buňky MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• molekulární struktura MeSH
• Mycobacterium tuberculosis cytologie   účinky léků   metabolismus   MeSH
• nukleosidy chemie   farmakologie   MeSH
• pyrrolidiny chemie   farmakologie   MeSH
• THP-1 buňky MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Acyclic nucleoside bisphosphonates (ANbPs) have previously been shown to be good inhibitors of human hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and Plasmodium falciparum (Pf) hypoxanthine-guanine-xanthine phosphoribosyltransferase (PfHGXPRT). On the basis of this scaffold, a new series of ANbPs was synthesized. One of these new ANbPs, [3-(guanine-9-yl)-2-((2-phosphonoethoxy)methyl)propoxy]methylphosphonic acid, exhibited Ki values of 6 and 70 nM for human HGPRT and Pf HGXPRT, respectively. These low Ki values were achieved by inserting an extra carbon atom in the linker connecting the N(9) atom of guanine to one of the phosphonate groups. The crystal structure of this ANbP in complex with human HGPRT was determined at 2.0 Å resolution and shows that it fills three key pockets in the active site. The most potent phosphoramidate prodrugs of these compounds have IC50 values in the low micromolar range in Pf lines and low toxicity in human A549 cells, demonstrating that these ANbPs are excellent antimalarial drug leads.

• MeSH
• antimalarika chemie   farmakologie   MeSH
• bisfosfonáty chemie   farmakologie   MeSH
• lidé MeSH
• nukleosidy chemie   farmakologie   MeSH
• pentosyltransferasy antagonisté a inhibitory   metabolismus   MeSH
• Plasmodium falciparum účinky léků   enzymologie   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• tropická malárie farmakoterapie   enzymologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH