A bioenergetikai profil vizsgálata 14C-glükóz és 14C-acetát oxidációjának összehasonlításával tumorsejtekben és tumoros szervezetben

A tumorsejtek anyagcseréjét a változó mikrokörnyezeti tényezõk mellett a tumornövekedést támogató genetikai mechanizmusok is befolyásolják. Napjainkban egyre nagyobb az igény a humán tumorok terápiás válaszreakcióinak vagy metabolikus profiljukra épülõ szubtípusainak vizsgálatára. A tumorsejtek és a tumort hordozó gazdaszervezet metabolikus/bioenergetikai jellegének tájékozódó igényû tanulmányozására alkalmas módszernek tartható a 14C-glükóz és 14C-acetát oxidációjának vizsgálata. Munkánkban radioaktívan jelölt bioenergetikai szubsztrátokból felszabaduló CO2 meghatározásával a tumorsejtek (in vitro sejtvonalak, illetve primer humán lymphocyták és leukaemiasejtek) és a tumoros szervezet (SCID, C57Bl/6) metabolikus aktivitását vizsgáltuk in vitro és in vivo. Megállapítottuk, hogy a szolid tumorból származó tumorsejtek többsége fokozottabban oxidálja a glükózt, mint az acetátot, míg a vérbõl izolált AML-, CML- és CLL-sejtek az acetátot oxidálták nagyobb mértékben, mint a glükózt in vitro. In vivo vizsgálatainkban azt tapasztaltuk, hogy a bioenergetikai szubsztrátok intravénás vagy per os adagolásakor kimutatható a tumorok hatása a gazdaszervezet glükóz-, illetve acetátoxidációjára. Elsõ adatot szolgáltattunk az emberi tumort hordozó gazdaszervezetek metabolikus profiljának változásáról xenograft modellen. Összefoglalva, eredményeink szerint több bioenergetikai szubsztrát oxidációjának összehasonlítása informatív módszer lehet a tumorsejtek in vitro, illetve a tumorok és a gazdaszervezet in vivo metabolikus profiljának vizsgálatában

Rapamycin (mTORC1 inhibitor) reduces the production of lactate and 2-hydroxyglutarate oncometabolites in IDH1 mutant fibrosarcoma cells

Background Multiple studies concluded that oncometabolites (e.g. D-2-hydroxyglutarate (2-HG) related to mutant isocitrate dehydrogenase 1/2 (IDH1/2) and lactate) have tumour promoting potential. Regulatory mechanisms implicated in the maintenance of oncometabolite production have great interest. mTOR (mammalian target of rapamycin) orchestrates different pathways, influences cellular growth and metabolism. Considering hyperactivation of mTOR in several malignancies, the question has been addressed whether mTOR operates through controlling of oncometabolite accumulation in metabolic reprogramming. Methods HT-1080 cells – carrying originally endogenous IDH1 mutation – were used in vitro and in vivo. Anti-tumour effects of rapamycin were studied using different assays. The main sources and productions of the oncometabolites (2-HG and lactate) were analysed by 13C-labeled substrates. Alterations at protein and metabolite levels were followed by Western blot, flow cytometry, immunohistochemistry and liquid chromatography mass spectrometry using rapamycin, PP242 and different glutaminase inhibitors, as well. Results Rapamycin (mTORC1 inhibitor) inhibited proliferation, migration and altered the metabolic activity of IDH1 mutant HT-1080 cells. Rapamycin reduced the level of 2-HG sourced mainly from glutamine and glucose derived lactate which correlated to the decreased incorporation of 13C atoms from 13C-substrates. Additionally, decreased expressions of lactate dehydrogenase A and glutaminase were also observed both in vitro and in vivo. Conclusions Considering the role of lactate and 2-HG in regulatory network and in metabolic symbiosis it could be assumed that mTOR inhibitors have additional effects besides their anti-proliferative effects in tumours with glycolytic phenotype, especially in case of IDH1 mutation (e.g. acute myeloid leukemias, gliomas, chondrosarcomas). Based on our new results, we suggest targeting mTOR activity depending on the metabolic and besides molecular genetic phenotype of tumours to increase the success of therapies

GABA, glutamine, glutamate oxidation and succinic semialdehyde dehydrogenase expression in human gliomas

Bioenergetic characterisation of malignant tissues revealed that different tumour cells can catabolise multiple substrates as salvage pathways, in response to metabolic stress. Altered metabolism in gliomas has received a lot of attention, especially in relation to IDH mutations, and the associated oncometabolite D-2-hydroxyglutarate (2-HG) that impact on metabolism, epigenetics and redox status. Astrocytomas and oligodendrogliomas, collectively called diffuse gliomas, are derived from astrocytes and oligodendrocytes that are in metabolic symbiosis with neurons; astrocytes can catabolise neuron-derived glutamate and gamma-aminobutyric acid (GABA) for supporting and regulating neuronal functions.Metabolic characteristics of human glioma cell models - including mitochondrial function, glycolytic pathway and energy substrate oxidation - in relation to IDH mutation status and after 2-HG incubation were studied to understand the Janus-faced role of IDH1 mutations in the progression of gliomas/astrocytomas. The metabolic and bioenergetic features were identified in glioma cells using wild-type and genetically engineered IDH1-mutant glioblastoma cell lines by metabolic analyses with Seahorse, protein expression studies and liquid chromatography-mass spectrometry.U251 glioma cells were characterised by high levels of glutamine, glutamate and GABA oxidation. Succinic semialdehyde dehydrogenase (SSADH) expression was correlated to GABA oxidation. GABA addition to glioma cells increased proliferation rates. Expression of mutated IDH1 and treatment with 2-HG reduced glutamine and GABA oxidation, diminished the pro-proliferative effect of GABA in SSADH expressing cells. SSADH protein overexpression was found in almost all studied human cases with no significant association between SSADH expression and clinicopathological parameters (e.g. IDH mutation).Our findings demonstrate that SSADH expression may participate in the oxidation and/or consumption of GABA in gliomas, furthermore, GABA oxidation capacity may contribute to proliferation and worse prognosis of gliomas. Moreover, IDH mutation and 2-HG production inhibit GABA oxidation in glioma cells. Based on these data, GABA oxidation and SSADH activity could be additional therapeutic targets in gliomas/glioblastomas

Determination of energy metabolites in cancer cells by porous graphitic carbon liquid chromatography – electrospray ionization mass spectrometry for the assessment of energy metabolism

A high performance liquid chromatography (HPLC) tandem mass spectrometric (MS/MS) method has been developed for the simultaneous determination of fifteen glucose, or acetate derived metabolites isolated from tumor cells. Glycolytic and tricarboxylic acid (TCA) cycle metabolites as well as acidic amino acids were separated on a HPLC porous graphitic carbon (PGC) column and simultaneously determined by means of triple quadrupole MS/MS using multiple reaction monitoring (MRM). Target compounds were eluted within 10 min with 8% v/v formic acid as an electronic modifier added to a 4:1 v/v methanol water mobile phase. The calibration is linear in the 1–100 μM concentration range for each analyte. The limit of detection ranges between 0.39 and 2.78 μM for the analytes concerned. To test the PGC–HPLC–MS/MS method in metabolomic studies, ZR-75.1 human mammary adenocarcinoma cells were labeled with U- 13C glucose or 1-13C acetate. Applying the MRM mode, the incorporation of 13C into metabolites, isolated from the tumor cells, and derived from glucose or acetate, could be properly identified

Additional file 2: Figure S2. of Rapamycin (mTORC1 inhibitor) reduces the production of lactate and 2-hydroxyglutarate oncometabolites in IDH1 mutant fibrosarcoma cells

The representative photos of p-mTOR, p-S6, LDH-A and Gls immunostainings in HT-1080 xenograft tumours. The expressions of p-mTOR, p-S6, LDH-A and Gls were studied in control and Rapamune treated xenograft tumours (DAB-brown staining; magnification 400X) (PDF 209 kb)