Author Correction: Inhibition of autophagic flux differently modulates cannabidiol-induced death in 2D and 3D glioblastoma cell cultures.
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ABSTRACT:
SUBMITTER: Ivanov VN
PROVIDER: S-EPMC8440618 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Radiotherapy combined with chemotherapy is the major treatment modality for human glioblastoma multiforme (GBM). GBMs eventually relapse after treatment and the average survival of GBM patients is less than two years. There is some evidence that cannabidiol (CBD) can induce cell death and increases the radiosensitivity of GBM by enhancing apoptosis. Beside initiation of death, CBD has been demonstrated as an inducer of autophagy. In the present study, we address the question whether CBD simultaneously induces a protective effect in GBM by upregulating autophagy. Addition of chloroquine that suppressed autophagic flux to 2D GBM cultures increased CBD-induced cell death, presenting proof for the protective autophagy. Blockage of autophagy upregulated radiation-induced cytotoxicity but only modestly affected the levels of cell death in CBD- or CBD/γ-irradiated 3D GBM cultures. Furthermore, CBD enhanced the pro-apoptotic activities of JNK1/2 and MAPK p38 signaling cascades while partially downregulated the pro-survival PI3K-AKT cascade, thereby changing a balance between cell death and survival. Suppression of JNK activation partially reduced CBD-induced cell death in 3D GBM cultures. In contrast, co-treatment of CBD-targeted cells with inhibitors of PI3K-AKT-NF-κB, IKK-NF-κB or JAK2-STAT3 pathways killed surviving GBM cells in both 2D and 3D cultures, potentially improving the therapeutic ratio of GBM.
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Project description:Autophagy (macroautophagy) is a highly conserved eukaryotic degradation pathway in which cytosolic components and organelles are sequestered by specialized autophagic membranes and degraded through the lysosomal system. The autophagic pathway maintains basal cellular homeostasis and helps cells adapt during stress; thus, defects in autophagy can cause detrimental effects. It is therefore crucial that autophagy is properly regulated. In this study, we show that the cysteine protease Atg4B, a key enzyme in autophagy that cleaves LC3, is an interactor of the small GTPase Rab7b. Indeed, Atg4B interacts and co-localizes with Rab7b on vesicles. Depletion of Rab7b increases autophagic flux as indicated by the increased size of autophagic structures as well as the magnitude of macroautophagic sequestration and degradation. Importantly, we demonstrate that Rab7b regulates LC3 processing by modulating Atg4B activity. Taken together, our findings reveal Rab7b as a novel negative regulator of autophagy through its interaction with Atg4B.
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Project description:Autophagy is a cell-survival pathway with dual role in tumorigenesis, promoting either tumor survival or tumor death. WNK2 gene, a member of the WNK (with no lysine (K)) subfamily, acts as a tumor suppressor gene in gliomas, regulating cell migration and invasion; however, its role in autophagy process is poorly explored. The WNK2-methylated human glioblastoma cell line A172 WT (wild type) was compared to transfected clones A172 EV (empty vector), and A172 WNK2 (WNK2 overexpression) for the evaluation of autophagy using an inhibitor (bafilomycin A1-baf A1) and an inducer (everolimus) of autophagic flux. Western blot and immunofluorescence approaches were used to monitor autophagic markers, LC3A/B and SQSTM1/p62. A172 WNK2 cells presented a significant decrease in LC3B and p62 protein levels, and in LC3A/B ratio when compared with control cells, after treatment with baf A1 + everolimus, suggesting that WNK2 overexpression inhibits the autophagic flux in gliomas. The mTOR pathway was also evaluated under the same conditions, and the observed results suggest that the inhibition of autophagy mediated by WNK2 occurs through a mTOR-independent pathway. In conclusion, the evaluation of the autophagic process demonstrated that WNK2 inhibits the autophagic flux in glioblastoma cell line.
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Project description:Diosmin, a natural flavone glycoside acquired through dehydrogenation of the analogous flavanone glycoside hesperidin, is plentiful in many citrus fruits. Glioblastoma multiforme (GBM) is the most malignant primary brain tumor; the average survival time of GBM patients is less than 18 months after standard treatment. The present study demonstrated that diosmin, which is able to cross the blood-brain barrier, inhibited GBM cell growth in vitro and in vivo. Diosmin also impeded migration and invasion by GBM8401and LN229 GBM cells by suppressing epithelial-mesenchymal transition, as indicated by increased expression of E-cadherin and decreased expression of Snail and Twist. Diosmin also suppressed autophagic flux, as indicated by increased expression of LC3-II and p62, and induced cell cycle arrest at G1 phase. Importantly, diosmin did not exert serious cytotoxic effects toward control SVG-p12 astrocytes, though it did reduce astrocyte viability at high concentrations. These findings provide potentially helpful support to the development of new therapies for the treatment of GBM.
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Project description:Drug resistance to temozolomide (TMZ) contributes to the majority of tumor recurrence and treatment failure in patients with glioblastoma multiforme (GBM). Autophagy has been reported to play a role in chemoresistance in various types of cancer, including GBM. The anticancer effect of statins is arousing great research interests and has been demonstrated to modulate autophagic function. In this study, we investigated the combinational effects of lovastatin and TMZ on treating U87 and U251 GBM cell lines. Cytotoxicity was measured by MTT and colony formation assays; apoptosis was measured by flow cytometry; the cellular autophagic function was detected by the EGFP-mRFP-LC3 reporter and western blot assay. The results showed that lovastatin might enhance the cytotoxicity of TMZ, increase the TMZ-induced cellular apoptosis, and impair the autophagic flux in GBM cells. Lovastatin triggered autophagy initiation possibly by inhibiting the Akt/mTOR signaling pathway. Moreover, lovastatin might impair the autophagosome-lysosome fusion machinery by suppressing LAMP2 and dynein. These results suggested that lovastatin could enhance the chemotherapy efficacy of TMZ in treating GBM cells. The mechanism may be associated with impaired autophagic flux and thereby the enhancement of cellular apoptosis. Combining TMZ with lovastatin could be a promising strategy for GBM treatment.
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Project description:Miz1 is a zinc finger protein that regulates expression of cell cycle inhibitors as part of a complex with Myc. Cell cycle-independent functions of Miz1 are poorly understood. Here, we use a Nestin-Cre transgene to delete an essential domain of Miz1 in the central nervous system (Miz1M-NM-^TPOZNes). Miz1M-NM-^TPOZNes mice display cerebellar neurodegeneration characterized by the progressive loss of Purkinje cells. Chromatin immunoprecipitation sequencing and biochemical analyses show that Miz1 activates transcription upon binding to a non-palindromic sequence present in core promoters. Target genes of Miz1 encode regulators of autophagy and proteins involved in vesicular transport that are required for autophagy. Miz1M-NM-^TPOZ neuronal progenitors and fibroblasts show reduced autophagic flux. Consistently, polyubiquitinated proteins and p62/Sqtm1 accumulate in the cerebella of Miz1M-NM-^TPOZNes mice, characteristic features of defective autophagy. Our data suggest that Miz1 may link cell growth and ribosome biogenesis to the transcriptional regulation of vesicular transport and autophagy. ChIP-Seq with H190 and G18 on an Illumina Genome Analyzer IIx.
2013-09-27 | E-GEOD-48602 | biostudies-arrayexpress
Project description:Impaired autophagy is known to cause mitochondrial dysfunction and heart failure, in part due to altered mitophagy and protein quality control. However, whether additional mechanisms are involved in the development of mitochondrial dysfunction and heart failure in the setting of deficient autophagic flux remains poorly explored. Here, we show that impaired autophagic flux reduces nicotinamide adenine dinucleotide (NAD+) availability in cardiomyocytes. NAD+ deficiency upon autophagic impairment is attributable to induction of nicotinamide N-methyltransferase (NNMT), which methylates the NAD+ precursor nicotinamide (NAM) to generate N-methyl-nicotinamide (MeNAM). The administration of nicotinamide mononucleotide (NMN) or inhibition of NNMT activity in autophagy-deficient hearts and cardiomyocytes restores NAD+ levels and ameliorates cardiac and mitochondrial dysfunction. Mechanistically, autophagic inhibition causes accumulation of SQSTM1, which activates NF-kB signaling and promotes NNMT transcription. In summary, we describe a novel mechanism illustrating how autophagic flux maintains mitochondrial and cardiac function by mediating SQSTM1-NF-kB-NNMT signaling and controlling the cellular levels of NAD+.
| S-SCDT-10_1038-S44318-023-00009-W | biostudies-other
Project description:Glioblastomas (GBM) grow in a rich neurochemical milieu, but the impact of neurochemicals on GBM growth is largely unexplored. We interrogated 680 neurochemical compounds in patient-derived GBM neural stem cells (GNS) to determine the effects on proliferation and survival. Compounds that modulate dopaminergic, serotonergic, and cholinergic signaling pathways selectively affected GNS growth. In particular, dopamine receptor D4 (DRD4) antagonists selectively inhibited GNS growth and promoted differentiation of normal neural stem cells. DRD4 antagonists inhibited the downstream effectors PDGFRβ, ERK1/2, and mTOR and disrupted the autophagy-lysosomal pathway, leading to accumulation of autophagic vacuoles followed by G0/G1 arrest and apoptosis. These results demonstrate a role for neurochemical pathways in governing GBM stem cell proliferation and suggest therapeutic approaches for GBM.
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Project description:Miz1 is a zinc finger protein that regulates expression of cell cycle inhibitors as part of a complex with Myc. Cell cycle-independent functions of Miz1 are poorly understood. Here, we use a Nestin-Cre transgene to delete an essential domain of Miz1 in the central nervous system (Miz1ΔPOZNes). Miz1ΔPOZNes mice display cerebellar neurodegeneration characterized by the progressive loss of Purkinje cells. Chromatin immunoprecipitation sequencing and biochemical analyses show that Miz1 activates transcription upon binding to a non-palindromic sequence present in core promoters. Target genes of Miz1 encode regulators of autophagy and proteins involved in vesicular transport that are required for autophagy. Miz1ΔPOZ neuronal progenitors and fibroblasts show reduced autophagic flux. Consistently, polyubiquitinated proteins and p62/Sqtm1 accumulate in the cerebella of Miz1ΔPOZNes mice, characteristic features of defective autophagy. Our data suggest that Miz1 may link cell growth and ribosome biogenesis to the transcriptional regulation of vesicular transport and autophagy.
2013-09-27 | GSE48602 | GEO
Project description:Doxorubicin (DOX) cardiotoxicity is an important factor of heart failure. The only clinically approved drug is dexrazoxane, while its side effect of secondary malignancies severely limited its application. It is urgent to find other alternative efficacious molecular for these chemotherapy patients. Colchicine is a safe and well tolerated anti-inflammation drug which also functions in attenuating the reactive oxygen species (ROS) generation. High dose of colchicine was reported block the autophagosome-lysosome fusion in cancer cells due to its destabilization effect to the microtubule system, while how colchicine affects the autophagic flux in cardiomyocytes is largely unknown. Recent years low dose of colchicine administration was reported helpful to the patients with pericarditis, postprocedural atrial fibrillation and coronary artery disease, most of the research attributed it to its anti-inflammation effect. Whether the autophagic flux regulated by colchicine also benefits to DOX induced heart failure remains unclear. Doxorubicin (DOX) administration was used to establish heart failure models in vivo and in vitro. Results showed that DOX blocked the autophagic vacuoles degradation, leading to damaged mitochondria and ROS accumulation. Heart failure characteristics were obviously improved after low dose of colchicine administration. Mechanistically, low dose of colchicine promoted the autolysosome degradation, cleared the damaged mitochondria, and ROS accumulation induced by the DOX and as a result attenuated DOX cardiotoxicity.
2024-06-20 | GSE247345 | GEO