Fusaric acid induces NRF2 as a cytoprotective response to prevent NLRP3 activation in the liver derived HepG2 cell line

Autophagy modulation changes mechano-chemical sensitivity of T24 bladder cancer cells

Bladder cancer cells possess unique adaptive capabilities: shaped by their environment, cells face a complex chemical mixture of metabolites and xenobiotics accompanied by physiological mechanical cues. These responses might translate into resistance to chemotherapeutical regimens and can largely rely on autophagy. Considering molecules capable of rewiring tumor plasticity, compounds of natural origin promise to offer valuable options. Fungal derived metabolites, such as bafilomycin and wortmannin are widely acknowledged as autophagy inhibitors. Here, their potential to tune bladder cancer cells´ adaptability to chemical and physical stimuli was assessed. Additionally, dietary occurring mycotoxins were also investigated, namely deoxynivalenol (DON, 0.1-10 µM) and fusaric acid (FA, 0.1-1 mM). Endowing a Janus' face behavior, DON and FA are on the one side described as toxins with detrimental health effects. Concomitantly, they are also explored experimentally for selective pharmacological applications including anticancer activities. In non-cytotoxic concentrations, bafilomycin (BAFI, 1-10 nM) and wortmannin (WORT, 1 µM) modified cell morphology and reduced cancer cell migration. Application of shear stress and inhibition of mechano-gated PIEZO channels reduced cellular sensitivity to BAFI treatment (1 nM). Similarly, for FA (0.5 mM) PIEZO1 expression and inhibition largely aligned with the modulatory potential on cancer cells motility. Additionally, this study highlighted that the activity profile of compounds with similar cytotoxic potential (e.g. co-incubation DON with BAFI or FA with WORT) can diverge substantially in the regulation of cell mechanotransduction. Considering the interdependence between tumor progression and response to mechanical cues, these data promise to provide a novel viewpoint for the study of chemoresistance and associated pathways.

Bisphenol A induces non-alcoholic fatty liver disease by promoting the O-GlcNAcylation of NLRP3

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease. The mechanism by which bisphenol A (BPA) promots NAFLD remains unclear. Palmitic acid (PA) and lipopolysaccharide (LPS) were used to simulate NAFLD in HepG2 cells in vitro. Total cholesterol (TC), triglyceride (TG) content, and lipid accumulation were measured to evaluate lipid metabolism. The caspase-1-stained cells and NLRP3 inflammasome-associated proteins were evaluated for pyroptosis. Western blot analysis was used to detect protein levels and co-immunoprecipitation (Co-IP) was used to detect the association between the proteins. Cycloheximide (CHX) treatment combined with western blot was performed to access protein stability. This data have shown that BPA induces lipid metabolism dysfunction and pyroptosis by upregulating O-GlcNAc transferase (OGT) level. NLRP3 directly interacts with OGT, and elevated OGT enhanced the stability of NLRP3 protein. BPA promoted OGT-mediated O-GlcNAcylation to stabilised NLRP3, thus accelerating NAFLD progress in vitro. Our study reveals that BPA, as an environmental factor, may be involved in the promotion of NAFLD, and that targeting NLRP3 and OGT may inhibit BPA's induction of NAFLD.

Determination of the effects of fusaric acid, a mycotoxin, on cytotoxicity, gamma-H2AX, 8-hydroxy-2 deoxyguanosine and DNA repair gene expressions in pancreatic cancer cells

Pancreatic cancer has a poor prognosis and is an important public health problem for developing countries. Oxidative stress plays an important role in cancer initiation, progression, proliferation, invasion, angiogenesis and metastasis. For this reason, one of the important strategic targets of new cancer therapeutics is to drive cancer cells into apoptosis through oxidative stress. In nuclear and mitochondrial DNA, 8-hydroxy-2'-deoxyguanosine and gamma-H2AX (γ-H2AX) are used as important oxidative stress biomarkers. Fusaric acid (FA) is a mycotoxin that mediates toxicity produced by Fusarium species and exhibits anticancer effects in various cancers via inducing apoptosis, cell cycle arrest, or other cellular mechanisms. The aim of this study was to determine the effects of fusaric acid on cytotoxic and oxidative damage in MIA PaCa-2 and PANC-1 cell lines. In this context, dose and time dependent cytotoxic effect of fusaric acid was determined by XTT method, mRNA expression levels of genes related to DNA repair were determined by RT-PCR, and its effect on 8-hydroxy-2'-deoxyguanosine and γ-H2AX levels was revealed by ELISA assay. According to XTT results, fusaric acid inhibits cell proliferation in MIA PaCa-2 and Panc-1 cells in a dose- and time-dependent manner. IC50 doses were determined as 187.74 μM at 48 h in MIA PaCa-2 cells and 134.83 μM at 48 h in PANC-1 cells, respectively. γ-H2AX and 8-OHdG changes were not found significant in pancreatic cancer cells. The mRNA expression levels of DNA repair-related genes NEIL1, OGG1, XRCC and Apex-1 change with exposure to fusaric acid. This study contributes to the therapeutic approaches to be developed for pancreatic cancer and demonstrates the potential of fusaric acid as an anticancer agent.

Moringa oleifera Lam Leaf Extract Stimulates NRF2 and Attenuates ARV-Induced Toxicity in Human Liver Cells (HepG2)

The World Health Organization (WHO) reported that there are 37 million individuals living with the human immunodeficiency virus (HIV) worldwide, with the majority in South Africa. This chronic disease is managed by the effective use of antiretroviral (ARV) drugs. However, with prolonged use, ARV drug-induced toxicity remains a clinically complex problem. This study investigated the toxicity of ARV drugs on mitochondria and the NRF2 antioxidant pathway and its possible amelioration using Moringa oleifera Lam (MO) leaf extracts. This medicinal plant has a range of functional bioactive compounds. Liver (HepG2) cells were treated with individual ARV drugs: Tenofovir disoproxil fumarate (TDF), Emtricitabine (FTC), and Lamivudine (3TC) for 96 h, followed by MO leaf extracts for 24 h. Intracellular ROS, cytotoxicity, lipid peroxidation, total and reduced glutathione (GSH), ATP, and mitochondrial polarisation were determined. Finally, protein (pNRF2, NRF2, SOD2, CAT, and Sirt3) and mRNA (NRF2, CAT, NQO1 SOD2, Sirt3, and PGC1α) expression were measured using Western blot and qPCR, respectively. TDF, FTC, and 3TC significantly increased intracellular ROS and extracellular levels of both MDA and LDH. ARVs also reduced the GSH and ATP levels and altered the mitochondrial polarization. Further, ARVs reduced the expression of NRF2 SOD2, Sirt3, CAT, NQO1, UCP2 and PGC1α mRNA and consequently pNRF2, NRF2, SOD2, Sirt3 and CAT protein. In contrast, there was a significant reduction in the extracellular MDA and LDH levels post-MO treatment. MO significantly reduced intracellular ROS while significantly increasing GSH, ATP, and mitochondrial membrane polarization. The addition of MO to ARV-treated cells significantly upregulated the expression of NRF2, SOD2, Sirt3, CAT, UCP2, PGC1α, and NQO1 mRNA and pNRF2, NRF2, SOD2, Sirt3 proteins. Thus, MO ameliorates ARV-induced hepatotoxicity by scavenging oxidants by inducing the NRF2 antioxidant pathway. MO shows great therapeutic potential and may be considered a potential supplement to ameliorate ARV drug toxicity.

NEAT1 Confers Radioresistance to Hepatocellular Carcinoma Cells by Inducing PINK1/Parkin-Mediated Mitophagy

A long noncoding RNA, nuclear paraspeckle assembly transcript 1 (NEAT1) variant 1 (NEAT1v1), confers radioresistance to hepatocellular carcinoma (HCC) cells by inducing autophagy via γ-aminobutyric acid A receptor-associated protein (GABARAP). Radiation induces oxidative stress to damage cellular components and organelles, but it remains unclear how NEAT1v1 protects HCC cells from radiation-induced oxidative stress via autophagy. To address this, we precisely investigated NEAT1v1-induced autophagy in irradiated HCC cell lines. X-ray irradiation significantly increased cellular and mitochondrial oxidative stress and mitochondrial DNA content in HCC cells while NEAT1v1 suppressed them. NEAT1v1 concomitantly induced the phosphatase and tensin homolog-induced kinase 1 (PINK1)/parkin-mediated mitophagy. Interestingly, parkin expression was constitutively upregulated in NEAT1v1-overexpressing HCC cells, leading to increased mitochondrial parkin levels. Superoxide dismutase 2 (SOD2) was also upregulated by NEAT1v1, and GABARAP or SOD2 knockdown in NEAT1v1-overexpressing cells increased mitochondrial oxidative stress and mitochondrial DNA content after irradiation. Moreover, it was suggested that SOD2 was involved in NEAT1v1-induced parkin expression, and that GABARAP promoted parkin degradation via mitophagy. This study highlights the unprecedented roles of NEAT1v1 in connecting radioresistance and mitophagy in HCC.

Metformin protects against neuroinflammation through integrated mechanisms of miR-141 and the NF-ĸB-mediated inflammasome pathway in a diabetic mouse model

The brain responds to diabetic stress by inducing the inflammatory response. Under normal circumstances this process is tightly regulated. However, uncontrolled inflammatory responses lead to compromised function and eventual neurodegeneration. The microRNA (miR)-200 family, specifically miR-141, is differentially expressed in diseased states including cognitive decline, thereby triggering changes in downstream genes. We hypothesised that Metformin (MF) regulates the miR-141/protein phosphatase 2A (PP2A) axis, and associated NF-ĸB-mediated inflammasome expression in diabetic mice brain. Diabetes was induced by intraperitoneal injection of Streptozotocin (STZ), thereafter mice were treated with MF (20 mg/kg BW). Whole brain tissue was harvested for further analysis. In silico analysis showed that Sirt1 and PP2A are prediction targets of miR-141. Selected protein and gene expressions were established through western blotting and qPCR, respectively. Diabetic mice brain tissue demonstrated overexpression of miR-141 and related pro-inflammatory factors as well as decreased PP2A gene expression. MF was able to counteract this by regulating expression of miR-141, PP2A, and p-tau at Ser396 protein expressions. Further experimentation revealed MF's inhibitory action on the inflammasome system by regulating the expression of the upstream controller NLRP3, related cytokines and NF-κB signalling pathway. Collectively, we demonstrate that MF promotes neuroprotection in diabetic mice by dampening inflammatory responses through its inhibitory effects on various signalling pathways. CATEGORIES: Inflammation and Immunopharmacology, Metabolic Disorders and Endocrinology, Neuropharmacology.