Bisphenol A is more potent than bisphenol S in influencing the physiological and pathological functions of lungs via inducing lung fibrosis and stimulating metastasis.

Bisphenol A (BPA) is widely used in the production of plastics, food containers, and receipt ink globally. However, research has identified it as an endocrine disruptor, affecting the hormonal balance in living organisms. Bisphenol S (BPS), one of the alternative substances, was developed, but its effects on human health and the underlying mechanisms remain unclarified. Specifically, research on the effects of oral exposure to bisphenol on the lungs is lacking. We examined the potential differences in toxicity between these compounds in lung cells in vitro and in vivo. Our toxicity mechanism studies on MRC5 and A549 cells exposed to BPA or BPS revealed that BPA induced actin filament abnormalities and activated epithelial-mesenchymal transition (EMT). This finding suggests an increased potential for lung fibrosis and metastasis in lung cancer. However, given that BPS was not detected at the administered dose and under the specific experimental conditions, the probability of these occurrences is considered minimal. Additionally, animal experiments confirmed that oral exposure to BPA activates EMT in the lungs. Our study provides evidence that prolonged oral exposure to BPA can lead to EMT activation in lung tissue, similar to that observed in cell experiments, suggesting the potential to induce lung fibrosis. This research emphasizes the importance of regulating the use of BPA to mitigate its associated pulmonary toxicity. Furthermore, it is significant that within the parameters of our experimental conditions, BPS did not exhibit the toxicological pathways clearly evident in BPA.

Long-chain perfluoroalkyl carboxylates induce cytoskeletal abnormalities and activate epithelial-mesenchymal transition in both renal cell carcinoma 3D cultures and Caki-1 xenografted mouse model.

Exposure to perfluorooctanoate (PFOA; a type of perfluoroalkyl carboxylates [PFACs]) may be correlated with the incidence of kidney cancer in individuals exposed to high levels of PFOA. However, mechanistic studies on the influence of PFACs on renal cell carcinoma (RCC) development are lacking. We explored the effects of five types of PFACs on RCC using in vitro and in vivo models to fill this knowledge gap and provide information for environmental/usage regulations. Using 2D/3D cultures of Caki-1 cells, a human clear cell RCC line, we examined the effects of short-chain (SC) PFACs and long-chain (LC) PFACs on RCC physio/pathological markers, including the cytoskeleton, epithelial-mesenchymal transition (EMT)-related proteins, and Na+/K+-ATPase. We also administered three different PFACs orally to mice harboring Caki-1 xenografts to assess the impact of these compounds on engrafted RCC in vivo. Compared with the effects of SCPFACs, mice with Caki-1 xenografts treated with LCPFACs showed increased EMT-related protein expression and exhibited liver toxicity. Therefore, LCPFACs induced EMT, influencing cancer metastasis activity, and displayed higher toxicity in vivo compared with SCPFACs. These findings improve our understanding of the effects of PFACs on RCC development and their corresponding in vivo toxicity, which is crucial for regulating these substances to protect public health.

Bisphenol A impairs renal function by reducing Na+/K+-ATPase and F-actin expression, kidney tubule formation in vitro and in vivo.

The kidney proximal tubule is responsible for reabsorbing water and NaCl to maintain the homeostasis of the body fluids, electrolytes, and nutrients. Thus, abnormal functioning of the renal proximal tubule can lead to life-threatening imbalances. Bisphenol A (BPA) has been used for decades as a representative chemical in household plastic products, but studies on its effects on the kidney proximal tubule are insufficient. In this study, immunocytochemical and cytotoxicity tests were performed using two- and three-dimensional human renal proximal tubular epithelial cell (hRPTEC) cultures to investigate the impact of low-dose BPA (1-10 µM) exposure. BPA was found to interfere with straight tubule formation as observed by low filamentous actin formation and reduced Na+/K+-ATPase expression in the tubules of hRPTEC 3D cultures. Similar results were observed in rat pup kidneys following oral administration of 250 mg/kg BPA. Moreover, the expression of HO-1 and 8-OHdG, key markers for oxidative stress, was increased in vitro and in vivo following BPA administration, whereas that of OAT1 and OAT, important transporters of the renal proximal tubules, was not altered. Overall, no-observed-adverse-effect-level (NOAEL)-dose BPA exposure can decrease renal function by promoting abnormal tubular formation both in vitro and in vivo. Therefore, we propose that although it does not exhibit life-threatening toxicity, exposure to low levels of BPA can negatively affect homeostasis in the body by means of long-term deterioration of renal proximal tubular function in humans.

Characteristics of Extracellular Vesicles and Preclinical Testing Considerations Prior to Clinical Applications.

Cell therapy products have significant limitations, such as storage instability, difficulties with transportation, and toxicity issues such as tumorigenicity and immunogenicity. Extracellular vesicles (EVs) secreted from cells show potential for therapeutic agent development. EVs have not been widely examined as investigational drugs, and non-clinical studies for the clinical approval of EV therapeutic agents are challenging. EVs contain various materials, such as DNA, cellular RNA, cytokines, chemokines, and microRNAs, but do not proliferate or divide like cells, thus avoiding safety concerns related to tumorigenicity. However, the constituents of EVs may induce the proliferation of normal cells; therefore, the suitability of vesicles should be verified through non-clinical safety evaluations. In this review, the findings of non-clinical studies on EVs are summarized. We describe non-clinical toxicity studies of EVs, which should be useful for researchers who aim to develop these vesicles into therapeutic agents. A new method for evaluating the immunotoxicity and tumorigenicity of EVs should also be developed.

Role of zinc dyshomeostasis in inflammasome formation in cultured cortical cells following lipopolysaccharide or oxygen-glucose deprivation/reperfusion exposure.

Exposure of mouse mixed cortical cell cultures to lipopolysaccharide (LPS) resulted in inflammasome formation in neurons and astrocytes, as indicated by increases in the levels of NLRP3, ASC, caspase-1, and IL-1ß. LPS exposure concurrently increased the level of free zinc in the cytosol of both cell types. Addition of the membrane-permeant zinc chelator TPEN blocked the increases in the levels of NLRP3 and caspase-1 as well as the release of inflammatory cytokines, indicating a role for increased zinc in LPS-induced inflammasome formation. Oxygen-glucose deprivation (OGD), a cellular model of hypoxia, also induced inflammasome formation and zinc dyshomeostasis in cortical cells, effects that were abolished upon zinc chelation with TPEN. A similar mechanism appeared to be at work in vivo. Whereas intraperitoneal injection of LPS in mice resulted in inflammasome formation and microglial activation in the brain, it caused little induction of inflammasome formation in ZnT3-null mice, which lack synaptic zinc, suggesting a specific role for synaptic zinc in LPS-induced formation of inflammasomes in the mouse brain.

Autism phenotypes in ZnT3 null mice: Involvement of zinc dyshomeostasis, MMP-9 activation and BDNF upregulation.

To investigate the role of synaptic zinc in the ASD pathogenesis, we examined zinc transporter 3 (ZnT3) null mice. At 4-5 weeks of age, male but not female ZnT3 null mice exhibited autistic-like behaviors. Cortical volume and neurite density were significantly greater in male ZnT3 null mice than in WT mice. In male ZnT3 null mice, consistent with enhanced neurotrophic stimuli, the level of BDNF as well as activity of MMP-9 was increased. Consistent with known roles for MMPs in BDNF upregulation, 2.5-week treatment with minocycline, an MMP inhibitor, significantly attenuated BDNF levels as well as megalencephaly and autistic-like behaviors. Although the ZnT3 null state removed synaptic zinc, it rather increased free zinc in the cytosol of brain cells, which appeared to increase MMP-9 activity and BDNF levels. The present results suggest that zinc dyshomeostasis during the critical period of brain development may be a possible contributing mechanism for ASD.

Abnormalities in the zinc-metalloprotease-BDNF axis may contribute to megalencephaly and cortical hyperconnectivity in young autism spectrum disorder patients.

Whereas aberrant brain connectivity is likely the core pathology of autism-spectrum disorder (ASD), studies do not agree as to whether hypo- or hyper-connectivity is the main underlying problem. Recent functional imaging studies have shown that, in most young ASD patients, cerebral cortical regions appear hyperconnected, and cortical thickness/brain size is increased. Collectively, these findings indicate that developing ASD brains may exist in an altered neurotrophic milieu. Consistently, some ASD patients, as well as some animal models of ASD, show increased levels of brain-derived neurotrophic factor (BDNF). However, how BDNF is upregulated in ASD is unknown. To address this question, we propose the novel hypothesis that a putative zinc-metalloprotease-BDNF (ZMB) axis in the forebrain plays a pivotal role in the development of hyperconnectivity and megalencephaly in ASD. We have previously demonstrated that extracellular zinc at micromolar concentrations can rapidly increase BDNF levels and phosphorylate the receptor tyrosine kinase TrkB via the activation of metalloproteases. The role of metalloproteases in ASD is still uncertain, but in fragile X syndrome, a monogenic disease with an autistic phenotype, the levels of MMP are increased. Early exposure to lipopolysaccharides (LPS) and other MMP activators such as organic mercurials also have been implicated in ASD pathogenesis. The resultant increases in BDNF levels at synapses, especially those involved in the zinc-containing, associative glutamatergic system may produce abnormal brain circuit development. Various genetic mutations that lead to ASD are also known to affect BDNF signaling: some down-regulate, and others up-regulate it. We hypothesize that, although both up- and down-regulation of BDNF may induce autism symptoms, only BDNF up-regulation is associated with the hyperconnectivity and large brain size observed in most young idiopathic ASD patients. To test this hypothesis, we propose to examine the ZMB axis in animal models of ASD. Synaptic zinc can be examined by fluorescence zinc staining. MMP activation can be measured by in situ zymography and Western blot analysis. Finally, regional levels of BDNF can be measured. Validating this hypothesis may shed light on the central pathogenic mechanism of ASD and aid in the identification of useful biomarkers and the development of preventive/therapeutic strategies.

Acridine yellow G blocks glioblastoma growth via dual inhibition of epidermal growth factor receptor and protein kinase C kinases.

Amplification of the epidermal growth factor receptor (EGFR), frequently expressed as a constitutively active deletion mutant (EGFRvIII), occurs commonly in glioblastoma multiformes (GBM). However, blockade of EGFR is therapeutically disappointing for gliomas with PTEN deletion. To search for small molecules treating this aggressive cancer, we have established a cell-based screening and successfully identified acridine yellow G that preferentially blocks cell proliferation of the most malignant U87MG/EGFRvIII cells over the less malignant U87MG/PTEN cells. Oral administration of this compound markedly diminishes the brain tumor volumes in both subcutaneous and intracranial models. It directly inhibits EGFR and PKCs with IC(50) values of ~7.5 and 5 µM, respectively. It dually inhibits EGFR and PKCs, resulting in a blockade of mammalian target of rapamycin signaling and cell cycle arrest in the G(1) phase, which leads to activation of apoptosis in the tumors. Hence, combinatorial inhibition of EGFR and PKCs might provide proof of concept in developing therapeutic agents for treating malignant glioma and other human cancers.

Akt-phosphorylated PIKE-A inhibits UNC5B-induced apoptosis in cancer cell lines in a p53-dependent manner.

UNC5B acts as a tumor suppressor, and it induces apoptosis in the absence of its cognate ligand netrins. UNC5B is a direct transcriptional target of p53 upon UV stimulation. Here we show that Akt phosphorylates PIKE-A and regulates its association with UNC5B and inhibits UNC5B-provoked apoptosis in a p53-dependent manner. PIKE-A GTPase binds active Akt and stimulates its kinase activity in a guanine-nucleotide-dependent way. Akt feeds back and phosphorylates PIKE-A on Ser-472 and subsequently enhances its stimulatory effect on Akt kinase activity. Akt activity is significantly reduced in PIKE -/- Mouse Embryonic Fibroblast (MEF) cells as compared to wild-type cells. PIKE-A directly interacts with UNC5B, which is regulated by netrin-1-activated Akt. Overexpression of PIKE-A diminishes UNC5B expression through down-regulation of p53. Knocking down PIKE-A stabilizes p53, increases UNC5B, and escalates UV-triggered apoptosis. Depletion of Akt abrogates PIKE-A's inhibitory effect on both p53 and UNC5B. Hence our findings support the notion that Akt--phosphorylated PIKE-A inhibits UNC5B-elicited apoptosis and reduces its expression level through inactivation of p53.

Insulin increases retinal hemorrhage in mild oxygen-induced retinopathy in the rat: inhibition by riluzole.

PURPOSE: Although hyperglycemia is likely the main stimulus for VEGF induction in diabetic retinopathy (DR), a switch from oral hypoglycemic therapy to parenteral insulin injection, despite producing better glucose control, sometimes paradoxically aggravates DR. The induction of VEGF by insulin, as observed in certain conditions, may be a plausible mechanism for this phenomenon. In the present study, to determine the role of insulin in proliferative diabetic retinopathy, the authors examined whether insulin treatment affected the outcome of oxygen-induced retinopathy (OIR) in rats and whether the anti-amyotrophic lateral sclerosis (ALS) drug riluzole with protein kinase C-inhibiting activity can attenuate the effects of insulin. METHODS: To examine in vivo the effects of insulin, mild OIR was produced in 7-day-old rat pups by raising them with a nursing mother in a 55% oxygen environment for 5 days. After that, rat pups were injected daily with subcutaneous saline or insulin (4 U/d) with or without additional riluzole injection (10 mg/kg/d, intraperitoneally) for 5 days in room air. RESULTS: Insulin treatment substantially increased VEGF levels, extraretinal vessel formation, matrix metalloproteinase activity, and the extent of retinal hemorrhage in rat pups with mild OIR compared with saline controls. Riluzole substantially reduced all these changes induced by insulin. CONCLUSIONS: In the present study, OIR was used as a surrogate model for DR because the core pathology and the VEGF-mediated mechanism are shared by both conditions. As in human DR, in rat pups with mild OIR, insulin treatment aggravated retinal hemorrhage, which was blocked by riluzole. Riluzole is a Food and Drug Administration-approved anti-ALS drug with a favorable adverse effect profile. It may be useful as an anti-VEGF treatment in DR, especially in reducing the retinal hemorrhage that often occurs shortly after the switch from oral hypoglycemics to parenteral insulin.

Riluzole inhibits VEGF-induced endothelial cell proliferation in vitro and hyperoxia-induced abnormal vessel formation in vivo.

PURPOSE: The present study examined the effects of riluzole, a Food and Drug Administration-approved drug for amyotrophic lateral sclerosis, on VEGF-stimulated endothelial cell proliferation in culture, and on neovascularization in a rat model of retinopathy of prematurity (ROP). METHODS: Human umbilical vein endothelial cell and bovine retinal endothelial cell cultures were treated with VEGF to induce endothelial cell proliferation in the presence or absence of riluzole. Activation of PKC betaII was examined by quantifying its phosphorylated form on immunoblots. ROP was induced in 5-day-old rat pups by raising them in hyperoxic conditions for 7 days and in normoxic conditions for the next 5 days. Dextran fluorescence retinal angiography was used to quantitatively assess ROP. RESULTS: Riluzole inhibited VEGF-stimulated PKC betaII activation and cell proliferation in bovine retinal endothelial cell and human umbilical vein endothelial cell cultures. In addition, systemic administration of riluzole substantially ameliorated abnormal new vessel formation in the rat ROP model. CONCLUSIONS: The present results suggest that riluzole is a potent inhibitor of VEGF-induced endothelial cell proliferation both in vivo and in vitro. Since long-term use of riluzole has already been proven safe in humans, the present data indicate that clinical trials of riluzole for proliferative retinopathies should be implemented expeditiously.

Protection by pyruvate of rat retinal cells against zinc toxicity in vitro, and pressure-induced ischemia in vivo.

PURPOSE: To examine whether zinc accumulation occurs during retinal neuronal death after pressure-induced ischemia in rats and whether pyruvate protects against such death. METHODS: To induce transient retinal ischemia, intraocular pressure was increased above systolic pressure for 65 minutes. Pyruvate was administered through the tail vein for 12 hours after ischemia to determine its effect on degeneration of retinal neurons. Retinas were removed and sectioned, and zinc accumulation was visualized with N-(6-methoxy-8-quinolyul)-p-carboxybenzoyl-sylphonamide (TFL-Zn) fluorescence microscopy, and neuronal death was determined with acid fuchsin staining. For in vitro studies, retinal cell cultures were prepared from newborn rat pups and used for experiments at days in vitro (DIV) 7 to 10. RESULTS: After retinal ischemia, staining revealed that most zinc-accumulating neurons were injured neurons, suggesting that endogenous zinc may contribute to ischemic neuronal death in the retina. In vitro studies showed that 15 minutes of exposure to 300 to 500 microM zinc resulted in the death of a substantial number of retinal cells in culture, and that this death was preceded by poly(ADP-ribose) polymerase (PARP)-mediated depletion of nicotinamide-adenine dinucleotide (NAD+) and adenosine triphosphate (ATP). Pyruvate, but not lactate, protected against this zinc-induced cell death in vitro. Consistent with this finding, in vivo studies showed that compared with control rats, pyruvate-treated rats had a substantial reduction in the number of cells showing signs of cell death. CONCLUSIONS: The present results suggest endogenous zinc contributes to retinal cell death after ischemia. Pyruvate potently protected against zinc toxicity in cultured rat retinal cells and reduced ischemia-induced cell death in rat retinas.