Endocytosis-mediated mitochondrial transplantation: Transferring normal human astrocytic mitochondria into glioma cells rescues aerobic respiration and enhances radiosensitivity

Abstract

Emerging evidence indicates that reprogramming of energy metabolism involving disturbances in energy production from a defect in cellular respiration with a shift to glycolysis is a core hallmark of cancer. Alterations in cancer cell energy metabolism are linked to abnormalities in mitochondrial function. Mitochondrial dysfunction of cancer cells includes increased glycolysis, decreased apoptosis, and resistance to radiotherapy. The study was designed for two main points: firstly, to investigate whether exogenous functional mitochondria can transfer into glioma cells and explore the underlying molecular mechanisms from the perspective of endocytosis; secondly, to further verify whether the mitochondrial transplantation is able to rescue aerobic respiration, attenuate the Warburg effect and enhance the radiosensitivity of gliomas. Methods: Mitochondria were isolated from normal human astrocytes (HA) and immediately co-incubated with starved human glioma cells (U87). Confocal microscopy and gene sequencing were performed to evaluate the ability of isolated mitochondria internalization into U87 cells. The interaction between endocytosis and isolated mitochondria transfer were captured by 3D tomographic microscopy and transmission electron microscopy. NAD + , CD38, cADPR and Ca 2+ release were determined by commercial kits, western blot, HLPC-MS and Fluo-3 AM respectively. PCR array expression profiling and Seahorse XF analysis were used to evaluate the effect of mitochondrial transplantation on energy phenotypes of U87 cells. U87 cells and U87 xenografts were both treated with mitochondrial transplantation, radiation, or a combination of mitochondrial transplantation and radiation. Apoptosis in vitro and in vivo were detected by cytochrome C, cleaved caspase 9 and TUNEL staining. Results: We found that mitochondria from HA could be transferred into starved U87 cells by simple co-incubation. Starvation treatment slowed the rate of glycolysis and decreased the transformation of NAD + to NADH in U87 cells. A large amount of accumulated NAD + was released into the extracellular space. CD38 is a member of the NAD + glycohydrolase family that catalyzes the cyclization of extracellular NAD + to intracellular cADPR. cADPR triggered release of Ca 2+ to promote cytoskeleton remodeling and plasma membrane invagination. Thus, endocytosis involving isolated mitochondria internalization was mediated by NAD + -CD38-cADPR-Ca 2+ signaling. Mitochondrial transfer enhanced gene and protein expression related to the tricarboxylic acid (TCA) cycle, increased aerobic respiration, attenuated glycolysis, reactivated the mitochondrial apoptotic pathway, inhibited malignant proliferation of U87 cells. Isolated mitochondria injected into U87...

Multifaceted Roles of Mitochondrial Components and Metabolites in Metabolic Diseases and Cancer

“…Beyond mitochondrial disease treatment, the transplantation of exogenous mitochondrial has been evaluated in the attempt to mitigate mitochondrial dysfunction of cancer cells. This approach has been shown to attenuate the Warburg effect and to enhance the sensitivity to anti-tumoral treatments (i.e., chemotherapy or radiotherapy) in breast cancer [ 188 ] or glioma cells [ 189 ].…”

“…Overall, and similar to what is observed in the rescue of damaged cells following intercellular mitochondria transfer from MSCs, studies testing the therapeutic efficacy of mitochondria transplantation indicate that mitochondria need to be functional to exert their beneficial effects [ 178 , 182 , 188 ]. Strikingly, mitochondria used for therapeutic purposes may be of autologous, allogeneic, or xenogeneic origin, because, in all the cases, transplanted mitochondria have been reported to be non-immunogenic [ 178 , 185 , 186 , 187 , 188 , 189 , 190 ]. Although the mitochondrial transplantation procedure remains largely experimental, this technique has been successfully applied in the damaged hearts of five pediatric patients sharing ischemia-reperfusion-associated myocardial dysfunction [ 191 ].…”

Improvement of cognitive and motor performance with mitotherapy in aged mice

“…When the microvesicles enter the cells, the fusion of the vesicle membrane with the cytosol membrane would potentially make the intact mitochondria into the cytosol [33]. The entry mechanism of mitochondria into cells would be associated with actin-mediated endocytosis because actin polymerization inhibitors can prevent the internalization of mitochondria by cells [34,35]. After the mitochondria enter cells, they are transported to lysosomes, then majority of the mitochondria can escape from the lysosomes and play roles in cytosol [36].…”

Mitochondrial Transplantation Improves Stroke-induced Brain Injury: Possible Involvement of Selective Component Recombination

“…No. C2006, Beyotime Biotechnology, Shanghai, China) based on a previously described method [41,42]. Single-cell suspensions of mNSCs and Neuro-2a cells were prepared and then coincubated with JC-1 working solution for 20 min at 37 ℃.…”