Mitochondria generate energy and building blocks required for cellular growth and function. The notion that mitochondria are not involved in the cancer growth has been challenged in recent years together with the emerging idea of mitochondria as a promising therapeutic target for oncologic diseases. Pentamethinium salts, cyan dyes with positively charged nitrogen on the benzothiazole or indole part of the molecule, were originally designed as mitochondrial probes. In this study, we show that pentamethinium salts have a strong effect on mitochondria, suppressing cancer cell proliferation and migration. This is likely linked to the strong inhibitory effect of the salts on dihydroorotate dehydrogenase (DHODH)-dependent respiration that has a key role in the de novo pyrimidine synthesis pathway. We also show that pentamethinium salts cause oxidative stress, redistribution of mitochondria, and a decrease in mitochondria mass. In conclusion, pentamethinium salts present novel anti-cancer agents worthy of further studies.
p53-mutated tumors often exhibit increased resistance to standard chemotherapy and enhanced metastatic potential. Here we demonstrate that inhibition of dihydroorotate dehydrogenase (DHODH), a key enzyme of the de novo pyrimidine synthesis pathway, effectively decreases proliferation of cancer cells via induction of replication and ribosomal stress in a p53- and checkpoint kinase 1 (Chk1)-dependent manner. Mechanistically, a block in replication and ribosomal biogenesis result in p53 activation paralleled by accumulation of replication forks that activate the ataxia telangiectasia and Rad3-related kinase/Chk1 pathway, both of which lead to cell cycle arrest. Since in the absence of functional p53 the cell cycle arrest fully depends on Chk1, combined DHODH/Chk1 inhibition in p53-dysfunctional cancer cells induces aberrant cell cycle re-entry and erroneous mitosis, resulting in massive cell death. Combined DHODH/Chk1 inhibition effectively suppresses p53-mutated tumors and their metastasis, and therefore presents a promising therapeutic strategy for p53-mutated cancers.
- MeSH
- checkpoint kinasa 1 antagonisté a inhibitory genetika metabolismus MeSH
- fenylmočovinové sloučeniny farmakologie MeSH
- geny erbB-2 MeSH
- HCT116 buňky MeSH
- inhibitory proteinkinas farmakologie MeSH
- kontrolní body buněčného cyklu * účinky léků MeSH
- leflunomid farmakologie MeSH
- lidé MeSH
- MFC-7 buňky MeSH
- myši inbrední BALB C MeSH
- myši inbrední NOD MeSH
- myši SCID MeSH
- myši transgenní MeSH
- nádorový supresorový protein p53 nedostatek genetika MeSH
- nádory prsu farmakoterapie genetika metabolismus patologie MeSH
- oxidoreduktasy působící na CH-CH vazby antagonisté a inhibitory genetika metabolismus MeSH
- proliferace buněk * účinky léků MeSH
- protokoly antitumorózní kombinované chemoterapie farmakologie MeSH
- pyraziny farmakologie MeSH
- pyrimidiny biosyntéza MeSH
- regulace genové exprese u nádorů MeSH
- ribozomy genetika metabolismus MeSH
- signální transdukce MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Unlike any protein studied so far, the active site of bilirubin oxidase from Myrothecium verrucaria contains a unique type of covalent link between tryptophan and histidine side chains. The role of this post-translational modification in substrate binding and oxidation is not sufficiently understood. Our structural and mutational studies provide evidence that this Trp396-His398 adduct modifies T1 copper coordination and is an important part of the substrate binding and oxidation site. The presence of the adduct is crucial for oxidation of substituted phenols and it substantially influences the rate of oxidation of bilirubin. Additionally, we bring the first structure of bilirubin oxidase in complex with one of its products, ferricyanide ion, interacting with the modified tryptophan side chain, Arg356 and the active site-forming loop 393-398. The results imply that structurally and chemically distinct types of substrates, including bilirubin, utilize the Trp-His adduct mainly for binding and to a smaller extent for electron transfer.
- MeSH
- bilirubin metabolismus MeSH
- Hypocreales metabolismus MeSH
- konformace proteinů MeSH
- molekulární modely * MeSH
- oxidace-redukce MeSH
- oxidoreduktasy působící na CH-CH vazby metabolismus MeSH
- transport elektronů fyziologie MeSH
- vazba proteinů fyziologie MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The development of non-genotoxic therapies that activate wild-type p53 in tumors is of great interest since the discovery of p53 as a tumor suppressor. Here we report the identification of over 100 small-molecules activating p53 in cells. We elucidate the mechanism of action of a chiral tetrahydroindazole (HZ00), and through target deconvolution, we deduce that its active enantiomer (R)-HZ00, inhibits dihydroorotate dehydrogenase (DHODH). The chiral specificity of HZ05, a more potent analog, is revealed by the crystal structure of the (R)-HZ05/DHODH complex. Twelve other DHODH inhibitor chemotypes are detailed among the p53 activators, which identifies DHODH as a frequent target for structurally diverse compounds. We observe that HZ compounds accumulate cancer cells in S-phase, increase p53 synthesis, and synergize with an inhibitor of p53 degradation to reduce tumor growth in vivo. We, therefore, propose a strategy to promote cancer cell killing by p53 instead of its reversible cell cycle arresting effect.
- MeSH
- antitumorózní látky farmakologie MeSH
- buněčný cyklus účinky léků MeSH
- indazoly farmakologie MeSH
- inhibitory enzymů farmakologie MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádorový supresorový protein p53 genetika metabolismus MeSH
- nádory farmakoterapie enzymologie genetika metabolismus MeSH
- oxidoreduktasy působící na CH-CH vazby antagonisté a inhibitory chemie genetika metabolismus MeSH
- proliferace buněk účinky léků MeSH
- proteolýza účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
Unlike angiosperms, gymnosperms use two different enzymes for the reduction of protochlorophyllide to chlorophyllide: the light-dependent protochlorophyllide oxidoreductase (LPOR) and the dark-operative protochlorophyllide oxidoreductase (DPOR). In this study, we examined the specific role of both enzymes for chlorophyll synthesis in response to different light/dark and temperature conditions at different developmental stages (cotyledons and needles) of Norway spruce (Picea abies Karst.). The accumulation of chlorophyll and chlorophyll-binding proteins strongly decreased during dark growth in secondary needles at room temperature as well as in cotyledons at low temperature (7 °C) indicating suppression of DPOR activity. The levels of the three DPOR subunits ChlL, ChlN, and ChlB and the transcripts of their encoding genes were diminished in dark-grown secondary needles. The low temperature had minor effects on the transcription and translation of these genes in cotyledons, which is suggestive for post-translational control in chlorophyll biosynthesis. Taking into account the higher solubility of oxygen at low temperature and oxygen sensitivity of DPOR, we mimicked low-temperature condition by the exposure of seedlings to higher oxygen content (33%). The treatment resulted in an etiolated phenotype of dark-grown seedlings, confirming an oxygen-dependent control of DPOR activity in spruce cotyledons. Moreover, light-dependent suppression of mRNA and protein level of DPOR subunits indicates that more efficiently operating LPOR takes over the DPOR function under light conditions, especially in secondary needles.
- MeSH
- chlorofyl genetika metabolismus MeSH
- oxidoreduktasy působící na CH-CH vazby biosyntéza metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- smrk enzymologie genetika metabolismus MeSH
- světlo MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Norsko MeSH
Leflunomide (LEF) is a disease-modifying anti-rheumatic drug used for treating rheumatoid arthritis (RA). More than 50% of patients are withdrawn from LEF treatment within one year, mainly due to AEs. Importantly, it is not possible to predict which patients will respond to LEF therapy nor if adverse outcome occurs. Pharmacogenetic studies indicate an impact of single nucleotid polymorphisms (SNPs) on the variability in LEF serum levels with potential relevance to effectiveness and tolerability in individual RA patients. In vitro studies have demonstrated that cytochromes P450 (CYPs), mainly CYP1A2, CYP2C19, and CYP3A4, are involved in LEF metabolite activation. It was shown that CYP1A2*1F allele may be associated with LEF toxicity in patients with RA. In case of dihydroorotate dehydrogenase (DHODH) gene SNP (rs3213422, 19C>A), it was shown that C allele may be associated with LEF toxicity and therapeutic effect. Finally, oestrogen receptor genes SNPs in females may be associated with LEF therapy efficacy. In summary, the results of the current studies suggest a possible diagnostic value of genotyping for patients with RA as biomarkers of LEF therapy efficacy or conversely as indicators of serious side effects. In the future, it will be necessary to corroborate these results in studies with larger numbers of patients and longer follow-up. Moreover, it would be appropriate to focus on CYP2C19, ATP5A1 and PKD1L3 genes.
- MeSH
- ABC transportéry genetika metabolismus MeSH
- antirevmatika škodlivé účinky farmakokinetika MeSH
- biotransformace genetika MeSH
- farmakogenetika MeSH
- fenotyp MeSH
- genotyp MeSH
- isoxazoly škodlivé účinky farmakokinetika MeSH
- izoenzymy MeSH
- jednonukleotidový polymorfismus * MeSH
- lidé MeSH
- nádorové proteiny genetika metabolismus MeSH
- oxidoreduktasy působící na CH-CH vazby genetika metabolismus MeSH
- receptory pro estrogeny genetika metabolismus MeSH
- revmatoidní artritida diagnóza farmakoterapie MeSH
- rizikové faktory MeSH
- systém (enzymů) cytochromů P-450 genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
In most oxygenic phototrophs, including cyanobacteria, two independent enzymes catalyze the reduction of protochlorophyllide to chlorophyllide, which is the penultimate step in chlorophyll (Chl) biosynthesis. One is light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) and the second type is dark-operative protochlorophyllide oxidoreductase (DPOR). To clarify the roles of both enzymes, we assessed synthesis and accumulation of Chl-binding proteins in mutants of cyanobacterium Synechocystis PCC 6803 that either completely lack LPOR or possess low levels of the active enzyme due to its ectopic regulatable expression. The LPOR-less mutant grew photoautotrophically in moderate light and contained a maximum of 20 % of the wild-type (WT) Chl level. Both Photosystem II (PSII) and Photosystem I (PSI) were reduced to the same degree. Accumulation of PSII was mostly limited by the synthesis of antennae CP43 and especially CP47 as indicated by the accumulation of reaction center assembly complexes. The phenotype of the LPOR-less mutant was comparable to the strain lacking DPOR that also contained <25 % of the wild-type level of PSII and PSI when cultivated under light-activated heterotrophic growth conditions. However, in the latter case, we detected no reaction center assembly complexes, indicating that synthesis was almost completely inhibited for all Chl-proteins, including the D1 and D2 proteins.
- MeSH
- 2D gelová elektroforéza MeSH
- aktivace enzymů MeSH
- bakteriální proteiny genetika metabolismus MeSH
- buněčná membrána enzymologie metabolismus MeSH
- chlorofyl biosyntéza genetika MeSH
- elektroforéza v polyakrylamidovém gelu MeSH
- fenotyp MeSH
- fotosystém I - proteinový komplex genetika metabolismus MeSH
- fotosystém II - proteinový komplex genetika metabolismus MeSH
- fototrofní procesy MeSH
- oxidoreduktasy působící na CH-CH vazby genetika metabolismus MeSH
- protochlorofylid metabolismus MeSH
- regulace genové exprese enzymů * MeSH
- regulace genové exprese u rostlin MeSH
- světlo MeSH
- Synechocystis enzymologie genetika metabolismus účinky záření MeSH
- transformace genetická MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
