Активність АТФ-аз постмітохондріальної фракції клітин лімфоми NK/Ly за дії бафіломіцинута НААДФ

Abstract

The system of active of transport of ions (ATPases) plays a critical role in cancer cells and is a potential target of anticancer therapy. A selective V-type H + -ATPase inhibitor – bafilomicine (Baf1A) was intensively studied as anticancer drug. It is known that H-ATPase creates the electrochemical gradients in the membranes of endo-lysosomal cells. These acidic stores are also Ca 2+ -containing organelles. The nicotinic acid adenine dinucleotide phosphate (NAADP) is a mediator of intracellular calcium signa­ling pathways. The role of NAADP-induced Ca 2+ transient in cancer cells is not understood. It’s correlation with activity of different ATPases in tumor cells is also poorly studied. The main goal of our study was to investigate the effects of Baf1A and NAADP on the activity of Na + /K + -ATPase, basal Mg 2+ -ATPase and Ca 2+ -ATPase of plasma membrane (PMCA) and endoplasmatic reticulum (SERCA) of NK/Ly murine lymphoma cells. All experiments were conducted on the postmitochondrial fraction of NK/Ly cells. We found that Baf1A (1 µМ) did not cause changes in activity of ATPase in postmitochondrial fraction of NK/Ly cells. It was revealed that NAADP (7 µМ) caused an increase of Na + /K + -ATPase activity by (54.18±7.84)% (n = 6, Р≤0.05) and PMCA by 3-fold (Р≤0.05) in subcellular fractions of NK/Ly cells. The activity of SERCA in membrane of cancer cells, as well as basal ATPase activity, were not changed upon NAADP application. Addition of Baf1A to the subcellular fraction of NK/Ly cells enhanced NAADP-induced increase in PMCA activity by 9.4-fold (n = 5, Р≤0.05), but NAADP-induced increase in Na + /K + -ATPase activity was slackened. We suggest that H + -ATPase functions independently on Na + /K + -ATPase as well as other ATPases identified in lymphoma membranes, due to its localization on cell surface. We found a correlation between the Н + -ATPase activity and pumps of PM (PMCA and Na + /K + -ATPase) only in presence of NAADP in subcellular fraction of NK/Ly cells. We consider that membranes of acidic stores are associated with PM in tumor cells. Keywords: tumor cells, NK/Ly lymphoma, ATPase, NAADP, Na + /K + -ATPase, PMCA, SERCA.