SDH complex
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The most important findings revealing pathogenesis, molecular characteristics, genotyping and targeted therapy of gastrointestinal stromal tumors (GISTs) are activated oncogenic mutations in KIT and PDGFRA genes. Imatinib mesylate (IM), which inhibits both KIT and PDGFRA receptors, significantly improved treatment of advanced (metastatic, recurrent, and/or inoperable) GISTs. However, in a significant number of patients the treatment fails due to the primary or secondary resistance to targeted therapy. Most common cause of secondary resistance is a presence of secondary mutations. Approximately 15% of adult patients with GISTs are negative for mutations in KIT or PDGFRA genes. These so-called wild-type GISTs appear to be characterized by other oncogenetic drivers, including mutations in BRAF, RAS, NF1 genes, and subunits of succinate dehydrogenase (SDH) complex. In the present study we investigated 261 tumour specimens from 239 patients with GIST. Primary mutations were detected in 82 % tumor specimens. 66 of them were in KIT, and 16 % in PDGFRA genes. Remaining 18 % were KIT/PDGFRA wild-type. Secondary KIT mutations were detected in 10 from 133 (7 %) patients treated with IM. We examined secondary KIT mutations in exons 13 and 17 and secondary PDGFRA mutation in exon 18 in sixteen progressive tumors and/or metastasis (from overall 22 samples). We identified BRAF V600E point mutation in 4 % of KIT/PDGFRA wild-type GIST patients. Moreover, we analysed SDH complex mutations in 4 younger patients (15, 33, 37, and 45 years old) from 44 patients without KIT, PDGFRA, and BRAF mutations. Two patients (a 37-year old man, and a 33-year old woman) had defects of the SDH complex. Our findings of mutational status of the primary and secondary KIT/PDGFRA mutations in patients with GIST confirm mechanisms of primary and secondary resistance, and also intralesional and interlesional heterogeneity of secondary mutations within and between progressive lesions. Moreover, detection of V600E BRAF mutation and defects of SDH complex in KIT/PDGFRA wild-type GISTs confirm their activation and allow for a selection of targeted therapy.
- MeSH
- chemorezistence genetika MeSH
- dospělí MeSH
- gastrointestinální nádory farmakoterapie genetika patologie MeSH
- gastrointestinální stromální tumory farmakoterapie genetika patologie MeSH
- genetická heterogenita MeSH
- genetická predispozice k nemoci MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mutace * MeSH
- mutační analýza DNA MeSH
- nádorové biomarkery genetika MeSH
- protinádorové látky terapeutické užití MeSH
- protoonkogenní proteiny B-raf genetika MeSH
- protoonkogenní proteiny c-kit genetika MeSH
- růstový faktor odvozený z trombocytů - receptor alfa genetika MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- sukcinátdehydrogenasa genetika MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Respiratory complex II (CII, succinate dehydrogenase, SDH) inhibition can induce cell death, but the mechanistic details need clarification. To elucidate the role of reactive oxygen species (ROS) formation upon the ubiquinone-binding (Qp) site blockade, we substituted CII subunit C (SDHC) residues lining the Qp site by site-directed mutagenesis. Cell lines carrying these mutations were characterized on the bases of CII activity and exposed to Qp site inhibitors MitoVES, thenoyltrifluoroacetone (TTFA) and Atpenin A5. We found that I56F and S68A SDHC variants, which support succinate-mediated respiration and maintain low intracellular succinate, were less efficiently inhibited by MitoVES than the wild-type (WT) variant. Importantly, associated ROS generation and cell death induction was also impaired, and cell death in the WT cells was malonate and catalase sensitive. In contrast, the S68A variant was much more susceptible to TTFA inhibition than the I56F variant or the WT CII, which was again reflected by enhanced ROS formation and increased malonate- and catalase-sensitive cell death induction. The R72C variant that accumulates intracellular succinate due to compromised CII activity was resistant to MitoVES and TTFA treatment and did not increase ROS, even though TTFA efficiently generated ROS at low succinate in mitochondria isolated from R72C cells. Similarly, the high-affinity Qp site inhibitor Atpenin A5 rapidly increased intracellular succinate in WT cells but did not induce ROS or cell death, unlike MitoVES and TTFA that upregulated succinate only moderately. These results demonstrate that cell death initiation upon CII inhibition depends on ROS and that the extent of cell death correlates with the potency of inhibition at the Qp site unless intracellular succinate is high. In addition, this validates the Qp site of CII as a target for cell death induction with relevance to cancer therapy.
- MeSH
- buněčná smrt fyziologie MeSH
- konformace proteinů MeSH
- lidé MeSH
- mitochondrie metabolismus fyziologie MeSH
- molekulární sekvence - údaje MeSH
- mutageneze cílená MeSH
- respirační komplex II chemie genetika metabolismus fyziologie MeSH
- sekvence aminokyselin MeSH
- ubichinon chemie genetika metabolismus MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Complex II of the respiratory chain (RC) recently emerged as a prominent regulator of cell death. In both cancer cells as well as neurodegenerative diseases, mutations in subunits have been found along with other genetic alterations indirectly affecting this complex. Anticancer compounds were developed that target complex II and cause cell death in a tumor-specific way. Our mechanistic understanding of how complex II is activated for cell death induction has recently been made clearer in recent studies, the results of which are covered in this review. This protein assembly is specifically activated for cell death via the dissociation of its SDHA and SDHB subunits from the membrane-anchoring proteins through pH change or mitochondrial Ca(2+) influx. The SDH activity contained in the SDHA/SDHB subcomplex remains intact and then generates, in an uncontrolled fashion, excessive amounts of reactive oxygen species (ROS) for cell death. Future studies on this mitochondrial complex will further elucidate it as a target for cancer treatments and reveal its role as a nexus for many diverse stimuli in cell death signaling.
- MeSH
- buněčná smrt fyziologie MeSH
- elektronový transportní řetězec fyziologie MeSH
- energetický metabolismus fyziologie MeSH
- mitochondrie fyziologie MeSH
- regulace genové exprese fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Mitochondrial complex II (CII), also called succinate dehydrogenase (SDH), is a central purveyor of the reprogramming of metabolic and respiratory adaptation in response to various intrinsic and extrinsic stimuli and abnormalities. In this review we discuss recent findings regarding SDH biogenesis, which requires four known assembly factors, and modulation of its enzymatic activity by acetylation, succinylation, phosphorylation, and proteolysis. We further focus on the emerging role of both genetic and epigenetic aberrations leading to SDH dysfunction associated with various clinical manifestations. This review also covers the recent discovery of the role of SDH in inflammation-linked pathologies. Conceivably, SDH is a potential target for several hard-to-treat conditions, including cancer, that remains to be fully exploited.
- MeSH
- lidé MeSH
- mitochondrie enzymologie metabolismus MeSH
- sukcinátdehydrogenasa metabolismus MeSH
- zánět metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Mitochondrial complex II or succinate dehydrogenase (SDH) is at the crossroads of oxidative phosphorylation and the tricarboxylic acid cycle. It has been shown that Sdh5 (SDHAF2/SDH5 in mammals) is required for flavination of the subunit Sdh1 (SDHA in human cells) in yeast. Here we demonstrate that in human breast cancer cells, SDHAF2/SDH5 is dispensable for SDHA flavination. In contrast to yeast, CRISPR-Cas9 nickase-mediated SDHAF2 KO breast cancer cells feature flavinated SDHA and retain fully assembled and functional complex II, as well as normal mitochondrial respiration. Our data show that SDHA flavination is independent of SDHAF2 in breast cancer cells, employing an alternative mechanism.
- MeSH
- flaviny MeSH
- genový knockdown MeSH
- lidé MeSH
- mitochondriální proteiny genetika metabolismus MeSH
- mitochondrie genetika metabolismus MeSH
- nádorové buněčné linie MeSH
- nádorové proteiny genetika metabolismus MeSH
- nádory prsu genetika metabolismus MeSH
- posttranslační úpravy proteinů * MeSH
- respirační komplex II genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Lipophilic bisphosphonium salts are among the most promising antiprotozoal leads currently under investigation. As part of their preclinical evaluation we here report on their mode of action against African trypanosomes, the etiological agents of sleeping sickness. The bisphosphonium compounds CD38 and AHI-9 exhibited rapid inhibition of Trypanosoma brucei growth, apparently the result of cell cycle arrest that blocked the replication of mitochondrial DNA, contained in the kinetoplast, thereby preventing the initiation of S-phase. Incubation with either compound led to a rapid reduction in mitochondrial membrane potential, and ATP levels decreased by approximately 50% within 1 h. Between 4 and 8 h, cellular calcium levels increased, consistent with release from the depolarized mitochondria. Within the mitochondria, the Succinate Dehydrogenase complex (SDH) was investigated as a target for bisphosphonium salts, but while its subunit 1 (SDH1) was present at low levels in the bloodstream form trypanosomes, the assembled complex was hardly detectable. RNAi knockdown of the SDH1 subunit produced no growth phenotype, either in bloodstream or in the procyclic (insect) forms and we conclude that in trypanosomes SDH is not the target for bisphosphonium salts. Instead, the compounds inhibited ATP production in intact mitochondria, as well as the purified F1 ATPase, to a level that was similar to 1 mM azide. Co-incubation with azide and bisphosphonium compounds did not inhibit ATPase activity more than either product alone. The results show that, in T. brucei, bisphosphonium compounds do not principally act on succinate dehydrogenase but on the mitochondrial FoF1 ATPase.
- MeSH
- adenosintrifosfát metabolismus MeSH
- azidy farmakologie MeSH
- buněčné linie MeSH
- membránový potenciál mitochondrií účinky léků MeSH
- mitochondriální DNA metabolismus MeSH
- mitochondrie účinky léků genetika metabolismus MeSH
- organofosforové sloučeniny chemie farmakologie MeSH
- protonové ATPasy metabolismus MeSH
- RNA interference MeSH
- sukcinátdehydrogenasa metabolismus MeSH
- trypanocidální látky farmakologie MeSH
- Trypanosoma brucei brucei cytologie účinky léků růst a vývoj MeSH
- trypanozomóza africká parazitologie MeSH
- vápník metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Feochromocytomy a paragangliomy jsou nádory vznikající z chromafinních buněk, mohou metabolizovat, skladovat, ale ne vždy vylučovat katecholaminy. Typickými projevy feochromocytomu nebo paragangliomu jsou hypertenze (trvalá i záchvatovitá), palpitace, bolesti hlavy a pocení. Se vznikem těchto nádorů je dnes spojeno deset genů a předpokládá se, že další budou objeveny. Oba typy nádorů se vyskytují také v rámci genetických syndromů: syndromu familiární paragangliomatózy (geny SDH, SDHAF2), syndromu von Hippel-Lindau (gen VHL), syndromu mnohočetné endokrinní neoplazie typu 2 (gen RET) a neurofibromatózy typu 1 (gen NF1). U některých syndromů jsou tyto nádory prvním a jediným manifestovaným onemocněním. Některé typy mutací, především v genu SDHB, jsou spojeny s vysokým počtem maligních onemocnění, která jsou v současné době standardními postupy nevyléčitelná. Z těchto důvodů je nezbytné provádět genetické vyšetření nejen u pacienta, ale v celé rodině, a nabídnout nositelům mutací dlouhodobé nebo celoživotní sledování a případně včasnou léčbu. Péče o pacienty s těmito onemocněními proto vyžaduje multidisciplinární spolupráci a měla by být prováděna pouze ve specializovaných centrech, která mají s tímto druhem onemocnění dostatečné zkušenosti.
Pheochromocytomas and paragangliomas are tumors arising from chromaffin cells. These tumors produce catecholamines and are typically found with symptoms and signs that may include hypertension (persistent or episodic), palpitations, headache and sweating. So far, 10 different genes have been associated with both tumors and other genes are expected to be detected. Pheochromocytoma and paraganglioma can occur as a part of genetic syndromes – familial paragangliomas (SDH genes, SDHAF2 gene), von Hippel-Lindau syndrome (VHL gene), multiple endocrine neoplasia type 2 (RET gene), and neurofibromatosis type 1 (NF1 gene). These tumors may be the first and only manifestation of these genetic syndromes. Patients with SDHB mutations are at high risk to develop malignant disease and unfortunately current therapeutic options for malignant form of disease are poor. Genetic testing plays a key role in the management of these tumors and therefore not only index patients with pheochromocytoma but also relatives should be tested. Management of this disease requires multidisciplinary cooperation and should be performed in the specialized medical centres.
- Klíčová slova
- genetické vyšetření, sledování,
- MeSH
- biologické markery krev MeSH
- bolesti hlavy MeSH
- chirurgie operační metody využití MeSH
- chromafinní buňky cytologie patologie MeSH
- diagnostické zobrazování metody využití MeSH
- feochromocytom diagnóza genetika terapie MeSH
- financování organizované MeSH
- genetické nemoci vrozené diagnóza genetika prevence a kontrola MeSH
- genetické testování MeSH
- hypertenze MeSH
- katecholaminy izolace a purifikace škodlivé účinky MeSH
- klinický obraz nemoci MeSH
- lidé MeSH
- paragangliom diagnóza genetika terapie MeSH
- podjednotky proteinů MeSH
- pooperační péče MeSH
- preventivní lékařství MeSH
- respirační komplex II genetika izolace a purifikace MeSH
- sukcinátdehydrogenasa genetika izolace a purifikace MeSH
- Check Tag
- lidé MeSH
Mitochondria play a pivotal role in apoptosis: permeabilization of the outer mitochondrial membrane and the release of pro-apoptotic proteins from the intermembrane space of mitochondria are regarded as the key event in apoptosis induction. Here we demonstrate how non-toxic doses of the mitochondrial Complex II inhibitor thenoyltrifluoroacetone (TTFA), which specifically inhibits the ubiquinone-binding site of succinate dehydrogenase (SDH), synergistically stimulated cell death, induced by harmless doses of cisplatin in a panel of chemoresistant neuroblastoma cell lines. Apoptotic cell death was confirmed by cytochrome c release from the mitochondria, cleavage of poly ADP-ribose polymerase, processing of caspase-3, which is an important executive enzyme in apoptosis, and caspase-3-like activity. Methyl malonate, an inhibitor of the SDHA subunit partially reversed apoptosis stimulated by TTFA in SK-N-BE(2) neuroblastoma cells (NB), indicating that sensitization requires oxidation of succinate. In contrast, in IMR-32 NB cells, the same concentrations of TTFA markedly suppressed cisplatin-induced apoptosis. Comparison of oxygen consumption in cisplatin-resistant SK-N-BE(2) and cisplatin-sensitive IMR-32 cells clearly demonstrated impaired Complex II activity in IMR-32 cells. We also found that in SK-N-BE(2) cells co-treatment with cisplatin and TTFA markedly stimulated formation of reactive oxygen species (ROS), whereas in IMR cells, cisplatin-mediated ROS production was attenuated by TTFA, which explains apoptosis suppression in these cells. Thus, functionally active SDH is a prerequisite for the ROS-mediated sensitization to treatment by TTFA.
- MeSH
- apoptóza účinky léků MeSH
- chemorezistence MeSH
- cílená molekulární terapie * MeSH
- cisplatina farmakologie MeSH
- kyselina jantarová metabolismus MeSH
- lidé MeSH
- mitochondrie účinky léků enzymologie MeSH
- nádorové buněčné linie MeSH
- nádorové proteiny antagonisté a inhibitory MeSH
- neuroblastom patologie MeSH
- oxidace-redukce MeSH
- protinádorové látky farmakologie MeSH
- reaktivní formy kyslíku metabolismus MeSH
- respirační komplex II antagonisté a inhibitory MeSH
- screeningové testy protinádorových léčiv MeSH
- spotřeba kyslíku účinky léků MeSH
- superoxidy metabolismus MeSH
- synergismus léků MeSH
- thenoyltrifluoraceton farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Inhibitors of the shikimate pathway are widely used as herbicides, antibiotics, and anti-infectious drugs. However, the regulation of the shikimic pathway is complex, and little is known about the feedback regulation of the shikimate dehydrogenase (SDH, EC 1.1.1.25) in plants. Thus, the aim of this study was to elucidate the kinetic mechanism of SDH purified from the root of Petroselinum crispum (parsley), to determine all possible reaction products and to identify phenylpropanoid compounds that affect its activity. Our results showed that the bisubstrate reaction catalyzed by P. crispum SDH follows a sequential ordered mechanism, except for three dead-end complexes. The main and lateral reactions of SDH were monitored by mass spectrometry, thereby detecting protocatechuic acid as a byproduct. Gallic acid was formed non-enzymatically, whereas quinate was not detected. Several polyphenolic compounds inhibited SDH activity, especially tannic, caffeic and chlorogenic acids, with IC50 0.014 mM, 0.15 mM, and 0.19 mM, respectively. The number of hydroxyl groups influenced their inhibition effect on SDH, and p-coumaric, t-ferulic, sinapic, syringic and salicylic acids were less effective SDH inhibitors. Nevertheless, one branch of the phenylpropanoid pathway may affect SDH activity through feedback regulation.
- MeSH
- alkoholoxidoreduktasy * MeSH
- katalýza MeSH
- kyselina shikimová MeSH
- petržel (rod) * MeSH
- Publikační typ
- časopisecké články MeSH
Succinate dehydrogenase (SDH), formed by four subunits SDHA, SDHB, SDHC, SDHD, and an assembly factor SDHAF2, functions as a key respiratory enzyme. Biallelic inactivation of genes encoding any of the components, almost always in the presence of a germline mutation, causes loss of function of the entire enzyme complex (so-called SDH deficiency) and subsequent development of SDH-deficient neoplasms which include pheochromocytoma/paraganglioma, gastrointestinal stromal tumor, and renal cell carcinoma (RCC). These tumors may occur in the same patient or kindred. SDH-deficient RCC shows distinctive morphological features with vacuolated eosinophilic cytoplasm due to distinctive cytoplasmatic inclusions containing flocculent material. The diagnosis is confirmed by loss of SDHB on immunohistochemistry with positive internal control. The majority of tumors occur in the setting of germline mutations in one of the SDH genes, most commonly SDHB. The prognosis is excellent for low-grade tumors but worse for high-grade tumors with high-grade nuclei, sarcomatoid change, or coagulative necrosis. Awareness of the morphological features and low-threshold for applying SDHB immunohistochemistry help identify patients with SDH-deficient RCC and hereditary SDH-deficient tumor syndromes. In this review we summarize recent development on the clinical and genetic features, diagnostic approach, and pitfalls of SDH-deficient syndrome, focusing on SDH-deficient renal cell carcinomas.
