4-O-methylascochlorin (MAC) is a derivative of ascochlorin, a prenyl-phenol compound antibiotic isolated from the fungus Ascochyta viciae. MAC induces caspase/poly (ADP-ribose) polymerase-mediated apoptosis in leukemi...
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4-O-methylascochlorin (MAC) is a derivative of ascochlorin, a prenyl-phenol compound antibiotic isolated from the fungus Ascochyta viciae. MAC induces caspase/poly (ADP-ribose) polymerase-mediated apoptosis in leukemia cells. However, the effects of MAC on autophagy in cancer cells and the underlying molecular mechanisms remain unknown. Here, we show that MAC induces autophagy in lung cancer cells. MAC significantly induced the expression of autophagy marker proteins including LC3-II, Beclin1, and ATG7. MAC promoted AMP-activated protein kinase (AMPK) phosphorylation and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream signalling proteins P70S6K and 4EBP1. The AMPK activator AICAR upregulated LC3-II expression through the AMPK/mTOR pathway similar to the effects of MAC. MAC-induced LC3-II protein expression was slightly reduced in AMPK siRNA transfected cells. MAC upregulated hypoxia-inducible factor-1 alpha (HIF-1 alpha) and bnip3, which are HIF-1 alpha-dependent autophagic proteins. Treatment with CoCl2, which mimics hypoxia, induced autophagy similar to the effect of MAC. The HIF-1 alpha inhibitor YC-1 and HIF-1 alpha siRNA inhibited the MAC-induced upregulation of LC3-II and bnip3. These results suggest that MAC induces autophagy via the AMPK/mTOR signalling pathway and by upregulating HIF-1 alpha and bnip3 protein expression in lung cancer cells.
Ginsenoside Rb1 (Rb1) possesses a cardioprotective effect via mediating microRNAs (miRs), while it is unexplored whether miR-210 is regulated by Rb1 in response to oxidative stress. Human endothelial ***926 cells were...
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Ginsenoside Rb1 (Rb1) possesses a cardioprotective effect via mediating microRNAs (miRs), while it is unexplored whether miR-210 is regulated by Rb1 in response to oxidative stress. Human endothelial ***926 cells were stimulated with H2O2 before Rb1 treatment. After transfection, cell viability, apoptosis, migration, and invasion assays were conducted. Western blot was applied to quantify protein. BCL2/adenovirus E1B 19-kDa interacting protein 3 (bnip3) and miR-210 were analyzed with quantitative reverse transcription polymerase chain reaction. Dual luciferase activity assay was performed. Rb1 elevated viability, migration, and invasion of H2O2-treated cells. H2O2-induced apoptosis was moderated by Rb1. miR-210 was augmented in H2O2-treated cells after Rb1 stimulation. miR-210 inhibitor abolished the positive effects of Rb1. bnip3 was negatively modulated by miR-210 and implicated in modulating viability, apoptosis, and migration and invasion. In addition, bnip3 modulated phosphorylation of regulators. Rb1 repressed oxidative injury via elevating miR-210. miR-210 negatively mediated bnip3, which participated in oxidative damage via regulating mammalian targets of rapamycin (mTOR) and nuclear factor-kappa B (NF-kappa B).
2020年8月12日,《自噬》(Autophagy)在线发表了陈忠教授、张翔南教授团队的最新研究成果“bnip3L/NIX degradation leads to mitophagy deficiency in ischemic brains”(https://***/doi/full/10.1080/15548627.2020.1802089)。
2020年8月12日,《自噬》(Autophagy)在线发表了陈忠教授、张翔南教授团队的最新研究成果“bnip3L/NIX degradation leads to mitophagy deficiency in ischemic brains”(https://***/doi/full/10.1080/15548627.2020.1802089)。
bnip3 is an atypical BH3-only member of the BCL-2 family of proteins with reported pro-death as well as pro-autophagic and cytoprotective functions, depending on the type of stress and cellular context. In line with t...
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bnip3 is an atypical BH3-only member of the BCL-2 family of proteins with reported pro-death as well as pro-autophagic and cytoprotective functions, depending on the type of stress and cellular context. In line with this, the role of bnip3 in cancer is highly controversial and increased bnip3 levels in cancer patients have been linked with both good as well as poor prognosis. In this study, using small hairpin RNA (shRNA) lentiviral transduction to stably knockdown bnip3 (bnip3-shRNA) expression levels in melanoma cells, we show that bnip3 supports cancer cell survival and long-term clonogenic growth. Although bnip3-shRNA increased mitochondrial mass and baseline levels of reactive oxygen species production, which are features associated with aggressive cancer cell behavior, it also prevented cell migration and completely abolished the ability to form a tubular-like network on matrigel, a hallmark of vasculogenic mimicry (VM). We found that this attenuated aggressive behavior of these melanoma cells was underscored by severe changes in cell morphology and remodeling of the actin cytoskeleton associated with loss of bnip3. Indeed, bnip3-silenced melanoma cells displayed enhanced formation of actin stress fibers and membrane ruffles, while lamellopodial protrusions and filopodia, tight junctions and adherens junctions were reduced. Moreover, loss of bnip3 resulted in re-organization of focal adhesion sites associated with increased levels of phosphorylated focal adhesion kinase. Remarkably, bnip3 silencing led to a drop of the protein levels of the integrin-associated protein CD47 and its downstream signaling effectors Rac1 and Cdc42. These observations underscore that bnip3 is required to maintain steady-state levels of intracellular complexes orchestrating the plasticity of the actin cytoskeleton, which is integral to cell migration and other vital processes stimulating cancer progression. All together these results unveil an unprecedented pro-tumorigenic role of BN
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