Autofagija i metaboličke promjene u diferencijaciji staničnih linija akutne mijeloične leukemije [Autography and metabolic changes in differentiation of acute myeloid leukemia cell lines]

Dembitz, Vilma (2017) Autofagija i metaboličke promjene u diferencijaciji staničnih linija akutne mijeloične leukemije [Autography and metabolic changes in differentiation of acute myeloid leukemia cell lines]. PhD thesis, Sveučilište u Zagrebu.

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Abstract

Pharmacological modulators of metabolism and AMP-dependent kinase (AMPK) inhibit proliferation of tumor cells. Our previous study demonstrated that 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), a compound commonly used as an AMPK-modulator, induced AMPK-independent differentiation of U937 cells. Autophagy has been described as an AMPK-independent effect of AICAR in other cells. Therefore, the aim of this study was to determine the role of autophagy and metabolism in differentiation of U937 cells. The results showed that AICAR-mediated effects were not mimicked by specific AMPK agonist and that AICAR had no significant effects on aerobic glycolysis. Long-term incubation of U937 cells with AICAR and other differentiation agents, all-trans-retinoic acid (ATRA) and phorbol 12-myristate 13-acetate, increased the expression of the autophagy marker LC3B-II. These effects were not observed in response to metformin, an AMPK agonist without differentiative properties. The increase in LC3B-II was due to the increase in autophagy flux and the autophagy inhibitor 3-methyladenine inhibited differentiation in response to all inducers. The effects of AICAR and ATRA on differentiation markers did not depend on Beclin-1, hVps34 and Atg7. These results show that AICAR and other differentiation agents induce autophagy flux in U937 cells and that differentiation does not depend on the classical or canonical autophagy pathway.

Abstract in Croatian

Farmakološki modulatori metabolizma i AMP-ovisne kinaze (AMPK) koče proliferaciju tumorskih stanica. U prethodnom radu pokazali smo da 5-aminoimidazol-4-karboksamid ribonukleotid (AICAR), spoj koji se često rabi kao agonist AMPK-a, potiče diferencijaciju stanica U937 neovisno o AMPK-u. Autofagija je opisana kao jedan od AMPK-neovisnih učinaka AICAR-a u drugim stanicama. Stoga je cilj ovog istraživanja bio odrediti ulogu autofagije i metabolizma u diferencijaciji stanica U937. Rezultati su pokazali da specifični aktivator AMPK-a ne oponaša učinke AICAR-a te da AICAR nema značajno djelovanje na aerobnu glikolizu. Dugotrajna inkubacija stanica U937 s AICAR-om i drugim diferencirajućim tvarima, sve-trans-retinskom kiselinom (ATRA-om) i forbol 12-miristatom 13-acetatom (PMA-om), povećala je izražaj biljega autofagije LC3B-II, a takvi učinci nisu zamijećeni u stanicama koje su inkubirane s metforminom, agonistom AMPK-a koji ne potiče diferencijaciju. Povećanje LC3B-II posljedica je povećanog protoka autofagije, a inhibitor autofagije 3-metiladenin je u potpunosti zakočio diferencijaciju u odgovoru na sve korištene diferencirajuće tvari. Učinci AICAR-a i ATRA-e na izražaj diferencijacijskih biljega ne ovise o količini Beclina-1, hVps34 i Atg7. Ovi rezultati pokazuju da AICAR i druge diferencirajuće tvari potiču autofagijski protok u stanicama U937 te da diferencijacija ne ovisi o klasičnom ili kanonskom putu autofagije.

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