Abstract Because of the ability to induce cell death in certain conditions, the fullerenes (C60 ) are potential anticancer and toxic agents. The colloidal suspension of crystalline C60 (nano-C60 , n ...C60 ) is extremely toxic, but the mechanisms of its cytotoxicity are not completely understood. By combining experimental analysis and mathematical modelling, we investigate the requirements for the reactive oxygen species (ROS)-mediated cytotoxicity of different n C60 suspensions, prepared by solvent exchange method in tetrahydrofuran (THF/ n C60 ) and ethanol (EtOH/ n C60 ), or by extended mixing in water (aqu/ n C60 ). With regard to their capacity to generate ROS and cause mitochondrial depolarization followed by necrotic cell death, the n C60 suspensions are ranked in the following order: THF/ n C60 >EtOH/ n C60 >aqu/ n C60 . Mathematical modelling of singlet oxygen (1 O2 ) generation indicates that the1 O2 -quenching power (THF/ n C60 <EtOH/ n C60 <aqu/ n C60 ) of the solvent intercalated in the fullerene crystals determines their ability to produce ROS and cause cell damage. These data could have important implications for toxicology and biomedical application of colloidal fullerenes.
In this review we analyze the ability of antipsychotic medications to modulate macroautophagy, a process of controlled lysosomal digestion of cellular macromolecules and organelles. We focus on its ...molecular mechanisms, consequences for the function/survival of neuronal and other cells, and the contribution to the beneficial and side-effects of antipsychotics in the treatment of schizophrenia, neurodegeneration, and cancer. A wide range of antipsychotics was able to induce neuronal autophagy as a part of the adaptive stress response apparently independent of mammalian target of rapamycin and dopamine receptor blockade. Autophagy induction by antipsychotics could contribute to reducing neuronal dysfunction in schizophrenia, but also to the adverse effects associated with their long-term use, such as brain volume loss and weight gain. In neurodegenerative diseases, antipsychotic-stimulated autophagy might help to increase the clearance and reduce neurotoxicity of aggregated proteotoxins. However, the possibility that some antipsychotics might block autophagic flux and potentially contribute to proteotoxin-mediated neurodegeneration must be considered. Finally, the anticancer effects of autophagy induction by antipsychotics make plausible their repurposing as adjuncts to standard cancer therapy.
Abstract The influence of fullerene (C60 ) nanoparticles on the cytotoxicity of a highly reactive free radical nitric oxide (NO) was investigated. Fullerene nanoparticles were prepared by ...mechanochemically assisted complexation with anionic surfactant sodium dodecyl sulfate, macrocyclic oligosaccharide γ-cyclodextrin or the copolymer ethylene vinyl acetate–ethylene vinyl versatate. C60 nanoparticles were characterized by UV–vis and atomic force microscopy. While readily internalized by mouse L929 fibroblasts, C60 nanoparticles were not cytotoxic. Moreover, they partially protected L929 cells from the cytotoxic effect of NO-releasing compounds sodium nitroprusside (SNP), S-nitroso- N -acetylpenicillamine (SNAP), S-nitrosoglutathione (GSNO) and 3-morpholino-sydnonimine (SIN-1). C60 nanoparticles reduced SNP-induced apoptotic cell death by preventing mitochondrial depolarization, caspase activation, cell membrane phosphatidylserine exposure and DNA fragmentation. The protective action of C60 nanoparticles was not exerted via direct interaction with NO, but through neutralization of mitochondria-produced superoxide radical in NO-treated cells, as demonstrated by using different redox-sensitive reporter fluorochromes. These data suggest that C60 complexes with appropriate host molecules might be plausible candidates for preventing NO-mediated cell injury in inflammatory/autoimmune disorders.
Abstract In the present study, we compared the effects of nanocrystalline fullerene suspension (nanoC60 ) on tumour cell growth in vitro and in vivo. NanoC60 suspension was prepared by solvent ...exchange using tetrahydrofuran to dissolve C60 . In vitro, nanoC60 caused oxidative stress, mitochondrial depolarization and caspase activation, leading to apoptotic and necrotic death in mouse B16 melanoma cells. Biodistribution studies demonstrated that intraperitoneally injected radiolabeled (125 I) nanoC60 readily accumulated in the tumour tissue of mice subcutaneously inoculated with B16 cells. However, intraperitoneal administration of nanoC60 over the course of two weeks starting from melanoma cell implantation not only failed to reduce, but significantly augmented tumour growth. The tumour-promoting effect of nanoC60 was accompanied by a significant increase in splenocyte production of the immunoregulatory free radical nitric oxide (NO), as well as by a reduction in splenocyte proliferative responses to T- and B-cell mitogens ConcanavalinA and bacterial lipopolysaccharide, respectively. A negative correlation between NO production and splenocyte proliferation indicated a possible role of NO in reducing the proliferation of splenocytes from nanoC60 -injected mice. These data demonstrate that nanoC60 , in contrast to its potent anticancer activity in vitro, can potentiate tumour growth in vivo, possibly by causing NO-dependent suppression of anticancer immune response.
We explored the interplay between the intracellular energy sensor AMP‐activated protein kinase (AMPK), extracellular signal‐regulated kinase (ERK), and autophagy in phorbol myristate acetate ...(PMA)‐induced neuronal differentiation of SH‐SY5Y human neuroblastoma cells. PMA‐triggered expression of neuronal markers (dopamine transporter, microtubule‐associated protein 2, β‐tubulin) was associated with an autophagic response, measured by the conversion of microtubule‐associated protein light chain 3 (LC3)‐I to autophagosome‐bound LC3‐II, increase in autophagic flux, and expression of autophagy‐related (Atg) proteins Atg7 and beclin‐1. This coincided with the transient activation of AMPK and sustained activation of ERK. Pharmacological inhibition or RNA interference‐mediated silencing of AMPK suppressed PMA‐induced expression of neuronal markers, as well as ERK activation and autophagy. A selective pharmacological blockade of ERK prevented PMA‐induced neuronal differentiation and autophagy induction without affecting AMPK phosphorylation. Conversely, the inhibition of autophagy downstream of AMPK/ERK, either by pharmacological agents or LC3 knockdown, promoted the expression of neuronal markers, thus indicating a role of autophagy in the suppression of PMA‐induced differentiation of SH‐SY5Y cells. Therefore, PMA‐induced neuronal differentiation of SH‐SY5Y cells depends on a complex interplay between AMPK, ERK, and autophagy, in which the stimulatory effects of AMPK/ERK signaling are counteracted by the coinciding autophagic response.
Phorbol myristate acetate (PMA) induces the expression of dopamine transporter, microtubule‐associated protein 2, and β‐tubulin, and subsequent neuronal differentiation of SH‐SY5Y neuroblastoma cells through AMP‐activated protein kinase (AMPK)‐dependent activation of extracellular signal‐regulated kinase (ERK). The activation of AMPK/ERK axis also induces the expression of beclin‐1 and Atg7, and increases LC3 conversion, thereby triggering the autophagic response that counteracts differentiation process.
Phorbol myristate acetate (PMA) induces the expression of dopamine transporter, microtubule‐associated protein 2, and β‐tubulin, and subsequent neuronal differentiation of SH‐SY5Y neuroblastoma cells through AMP‐activated protein kinase (AMPK)‐dependent activation of extracellular signal‐regulated kinase (ERK). The activation of AMPK/ERK axis also induces the expression of beclin‐1 and Atg7, and increases LC3 conversion, thereby triggering the autophagic response that counteracts differentiation process.
Cover Image for this issue: doi: 10.1111/jnc.12872.
We investigated the ability of 19 recently synthesized arylpiperazine compounds to protect human SH-SY5Y neuroblastoma cells from the neurotoxin 6-hydroxydopamine (6-OHDA). The compound with the most ...potent neuroprotective action was N-{3-2-(4-phenyl-piperazin-1-yl)-ethyl-phenyl}-picolinamide (6b), which reduced 6-OHDA-induced apoptotic death through stabilization of mitochondrial membrane and subsequent prevention of superoxide production, caspase activation and DNA fragmentation. 6-OHDA-triggered autophagic response was also reduced by 6b, which prevented inactivation of the main autophagy repressor mTOR, upregulation of proautophagic beclin-1, conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to autophagosome-associated LC3-II, as well as intracytoplasmic acidification induced by 6-OHDA. The inhibition of autophagy using LC3β gene silencing or pharmacological autophagy blockers 3-methyladenine or bafilomycin A1, mimicked the cytoprotective effect of 6b. While the treatment with 6b had no effect on the phosphorylation of proapoptotic MAP kinases ERK and JNK, it markedly increased the phosphorylation of the prosurvival kinase Akt in 6-OHDA-treated cells. Akt inhibitor DEBC or RNA interference-mediated Akt silencing reduced the ability of 6b to block 6-OHDA-triggered apoptotic and autophagic responses, thus confirming their dependency on Akt activation. The cytoprotective effect of 6b was also observed in 6-OHDA-treated neuronal PC12 cells, but not in SH–SY5Y or PC12 cells exposed to 1-methyl-4-phenylpyridinium, indicating that the observed neuroprotection was dependent on the cytotoxic stimulus. Because of the ability to prevent 6-OHDA induced apoptotic/autophagic cell death through activation of Akt, the investigated arylpiperazines could be potential candidates for treatment of neurodegenerative diseases.
•The in vitro neuroprotective action of novel arylpiperazine compounds was assessed.•Arylpiperazines protect SH-SY5Y neuroblastoma cells from the neurotoxin 6-OHDA.•Arylpiperazines block 6-OHDA-triggered mitochondrial damage and oxidative stress.•Arylpiperazines reduce 6-OHDA-induced apoptotic and autophagic cell death.•Neuroprotective action of arylpiperazines is mediated by Akt.
In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our ...knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
Metformin has been known to treat type 2 diabetes for decades and is widely prescribed antidiabetic drug. Recently, its anticancer potential has also been discovered. Moreover, metformin has low cost ...thus it has attained profound research interest. Comprehensing the complexity of the molecular regulatory networks in cancer provides a mode for advancement of research in cancer development and treatment. Metformin targets many pathways that play an important role in cancer cell survival outcome. Here, we described anticancer activity of metformin on the AMPK dependent/independent mechanisms regulating metabolism, oncogene/tumor suppressor signaling pathways together with the issue of clinical studies. We also provided brief overwiev about recently described metformin’s role in cancer immunity. Insight in these complex molecular networks, will simplify application of metformin in clinical trials and contribute to improvement of anti-cancer therapy.
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