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At least 1,045 records · Page 58
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DOE OSTI2013

Epithelial to mesenchymal transition in arsenic-transformed cells promotes angiogenesis through activating β-catenin–vascular endothelial growth factor pathway

Arsenic exposure represents a major health concern increasing cancer risks, yet the mechanism of arsenic carcinogenesis has not been elucidated. We and others recently reported that cell malignant transformation by arsenic is accompanied by epithelial to mesenchymal transition (EMT). However, the role of EMT in arsenic carcinogenesis is not well understood. Although previous studies showed that short term exposure of endothelial cells to arsenic stimulated angiogenesis, it remains to be determined whether cells that were malignantly transformed by long term arsenic exposure have a pro-angiogenic effect. The objective of this study was to investigate the effect of arsenic-transformed human bronchial epithelial cells that underwent EMT on angiogenesis and the underlying mechanism. It was found that the conditioned medium from arsenic-transformed cells strongly stimulated tube formation by human umbilical vein endothelial cells (HUVECs). Moreover, enhanced angiogenesis was detected in mouse xenograft tumor tissues resulting from inoculation of arsenic-transformed cells. Mechanistic studies revealed that β-catenin was activated in arsenic-transformed cells up-regulating its target gene expression including angiogenic-stimulating vascular endothelial growth factor (VEGF). Stably expressing microRNA-200b in arsenic-transformed cells that reversed EMT inhibited β-catenin activation, decreased VEGF expression and reduced tube formation by HUVECs. SiRNA knockdown β-catenin decreased VEGF expression. Adding a VEGF neutralizing antibody into the conditioned medium from arsenic-transformed cells impaired tube formation by HUVECs. Reverse transcriptase-PCR analysis revealed that the mRNA levels of canonical Wnt ligands were not increased in arsenic-transformed cells. These findings suggest that EMT in arsenic-transformed cells promotes angiogenesis through activating β-catenin–VEGF pathway. - Highlights: • Arsenic-transformed cells that underwent EMT displayed a pro-angiogenic effect. • EMT in arsenic-transformed cells activates β-catenin. • β-Catenin activation increases VEGF expression in arsenic-transformed cells. • β-Catenin activation is likely independent of canonical Wnt signaling. • EMT in arsenic-transformed cells promotes angiogenesis via β-catenin–VEGF pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Inhibition of inflammatory mediators contributes to the anti-inflammatory activity of KYKZL-1 via MAPK and NF-κB pathway

KYKZL-1, a newly synthesized compound with COX/5-LOX dual inhibition, was subjected to the anti-inflammatory activity test focusing on its modulation of inflammatory mediators as well as intracellular MAPK and NF-κB signaling pathways. In acute ear edema model, pretreatment with KYKZL-1 (p.o.) dose-dependently inhibited the xylene-induced ear edema in mice with a higher inhibition than diclofenac. In a three-day TPA-induced inflammation, KYKZL-1 also showed significant anti-inflammatory activity with inhibition ranging between 20% and 64%. In gastric lesion test, KYKZL-1 elicited markedly fewer stomach lesions with a low index of ulcer as compared to diclofenac in rats. In further studies, KYKZL-1 was found to significantly inhibit the production of NO, PGE{sub 2}, LTB{sub 4} in LPS challenged RAW264.7, which is parallel to its attenuation of the expression of iNOS, COX-2, 5-LOX mRNAs or proteins and inhibition of phosphorylation of p38 and ERK MAPKs and activation of NF-κB. Taken together, our data indicate that KYKZL-1 comprises dual inhibition of COX and 5-LOX and exerts an obvious anti-inflammatory activity with an enhanced gastric safety profile via simultaneous inhibition of phosphorylation of p38 and ERK MAPKs and activation of NF-κB. - Highlights: • KYKZL-1 is designed to exhibit COX/5-LOX dual inhibition. • KYKZL-1 inhibits NO, PGE{sub 2} and LTB{sub 4} and iNOS, COX-2 and 5-LOX mRNAs and MAPKs. • KYKZL-1 inhibits phosphorylation of MAPKs. • KYKZL-1 inactivates NF-κB pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

OSU-A9 inhibits angiogenesis in human umbilical vein endothelial cells via disrupting Akt–NF-κB and MAPK signaling pathways

Since the introduction of angiogenesis as a useful target for cancer therapy, few agents have been approved for clinical use due to the rapid development of resistance. This problem can be minimized by simultaneous targeting of multiple angiogenesis signaling pathways, a potential strategy in cancer management known as polypharmacology. The current study aimed at exploring the anti-angiogenic activity of OSU-A9, an indole-3-carbinol-derived pleotropic agent that targets mainly Akt–nuclear factor-kappa B (NF-κB) signaling which regulates many key players of angiogenesis such as vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). Human umbilical vein endothelial cells (HUVECs) were used to study the in vitro anti-angiogenic effect of OSU-A9 on several key steps of angiogenesis. Results showed that OSU-A9 effectively inhibited cell proliferation and induced apoptosis and cell cycle arrest in HUVECs. Besides, OSU-A9 inhibited angiogenesis as evidenced by abrogation of migration/invasion and Matrigel tube formation in HUVECs and attenuation of the in vivo neovascularization in the chicken chorioallantoic membrane assay. Mechanistically, Western blot, RT-PCR and ELISA analyses showed the ability of OSU-A9 to inhibit MMP-2 production and VEGF expression induced by hypoxia or phorbol-12-myristyl-13-acetate. Furthermore, dual inhibition of Akt–NF-κB and mitogen-activated protein kinase (MAPK) signaling, the key regulators of angiogenesis, was observed. Together, the current study highlights evidences for the promising anti-angiogenic activity of OSU-A9, at least in part through the inhibition of Akt–NF-κB and MAPK signaling and their consequent inhibition of VEGF and MMP-2. These findings support OSU-A9's clinical promise as a component of anticancer therapy. - Highlights: • The antiangiogenic activity of OSU-A9 in HUVECs was explored. • OSU-A9 inhibited HUVECs proliferation, migration, invasion and tube formation. • OSU-A9 targeted signaling pathways mediated by Akt-NF-kB, VEGF, and MMP-2. • The anti-angiogenic activity of OSU-A9 supports its clinical promise.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Anticancer effect of genistein on BG-1 ovarian cancer growth induced by 17 β-estradiol or bisphenol A via the suppression of the crosstalk between estrogen receptor alpha and insulin-like growth factor-1 receptor signaling pathways

The interaction between estrogen receptor (ER) and insulin-like growth factor-1 receptor (IGF-1R) signaling pathway plays an important role in proliferation of and resistance to endocrine therapy to estrogen dependent cancers. Estrogen (E2) upregulates the expression of components of IGF-1 system and induces the downstream of mitogenic signaling cascades via phosphorylation of insulin receptor substrate-1 (IRS-1). In the present study, we evaluated the xenoestrogenic effect of bisphenol A (BPA) and antiproliferative activity of genistein (GEN) in accordance with the influence on this crosstalk. BPA was determined to affect this crosstalk by upregulating mRNA expressions of ERα and IGF-1R and inducing phosphorylation of IRS-1 and Akt in protein level in BG-1 ovarian cancer cells as E2 did. In the mouse model xenografted with BG-1 cells, BPA significantly increased a tumor burden of mice and expressions of ERα, pIRS-1, and cyclin D1 in tumor mass compared to vehicle, indicating that BPA induces ovarian cancer growth by promoting the crosstalk between ER and IGF-1R signals. On the other hand, GEN effectively reversed estrogenicity of BPA by reversing mRNA and protein expressions of ERα, IGF-1R, pIRS-1, and pAkt induced by BPA in cellular model and also significantly decreased tumor growth and in vivo expressions of ERα, pIRS-1, and pAkt in xenografted mouse model. Also, GEN was confirmed to have an antiproliferative effect by inducing apoptotic signaling cascades. Taken together, these results suggest that GEN effectively reversed the increased proliferation of BG-1 ovarian cancer by suppressing the crosstalk between ERα and IGF-1R signaling pathways upregulated by BPA or E2.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

TRPM7 channel regulates PDGF-BB-induced proliferation of hepatic stellate cells via PI3K and ERK pathways

TRPM7, a non-selective cation channel of the TRP channel superfamily, is implicated in diverse physiological and pathological processes including cell proliferation. Recently, TRPM7 has been reported in hepatic stellate cells (HSCs). Here, we investigated the contribution role of TRPM7 in activated HSC-T6 cell (a rat hepatic stellate cell line) proliferation. TRPM7 mRNA and protein were measured by RT-PCR and Western blot in rat model of liver fibrosis in vivo and PDGF-BB-activated HSC-T6 cells in vitro. Both mRNA and protein of TRPM7 were dramatically increased in CCl{sub 4}-treated rat livers. Stimulation of HSC-T6 cells with PDGF-BB resulted in a time-dependent increase of TRPM7 mRNA and protein. However, PDGF-BB-induced HSC-T6 cell proliferation was inhibited by non-specific TRPM7 blocker 2-aminoethoxydiphenyl borate (2-APB) or synthetic siRNA targeting TRPM7, and this was accompanied by downregulation of cell cycle proteins, cyclin D1, PCNA and CDK4. Blockade of TRPM7 channels also attenuated PDGF-BB induced expression of myofibroblast markers as measured by the induction of α-SMA and Col1α1. Furthermore, the phosphorylation of ERK and AKT, associated with cell proliferation, decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TRPM7 channels contribute to perpetuated fibroblast activation and proliferation of PDGF-BB induced HSC-T6 cells via the activation of ERK and PI3K pathways. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis. - Highlights: • Upregulation of TRPM7 mRNA and protein in the fibrotic livers from CCl{sub 4}-treated rats. • Increasing expression of TRPM7 mRNA and protein during HSC activation. • Blockade of TRPM7 inhibited the PDGF-BB induced proliferation of HSC-T6 cells. • Blockade of TRPM7 decreased α-SMA and Col1α1 expressions in activated HSC-T6 cells. • TRPM7 up-regulation contributes to the activation of ERK and AKT pathways.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Carbon monoxide alleviates ethanol-induced oxidative damage and inflammatory stress through activating p38 MAPK pathway

Stress-inducible protein heme oxygenase-1(HO-1) is well-appreciative to counteract oxidative damage and inflammatory stress involving the pathogenesis of alcoholic liver diseases (ALD). The potential role and signaling pathways of HO-1 metabolite carbon monoxide (CO), however, still remained unclear. To explore the precise mechanisms, ethanol-dosed adult male Balb/c mice (5.0 g/kg.bw.) or ethanol-incubated primary rat hepatocytes (100 mmol/L) were pretreated by tricarbonyldichlororuthenium (II) dimmer (CORM-2, 8 mg/kg for mice or 20 μmol/L for hepatocytes), as well as other pharmacological reagents. Our data showed that CO released from HO-1 induction by quercetin prevented ethanol-derived oxidative injury, which was abolished by CO scavenger hemoglobin. The protection was mimicked by CORM-2 with the attenuation of GSH depletion, SOD inactivation, MDA overproduction, and the leakage of AST, ALT or LDH in serum and culture medium induced by ethanol. Moreover, CORM-2 injection or incubation stimulated p38 phosphorylation and suppressed abnormal Tnfa and IL-6, accompanying the alleviation of redox imbalance induced by ethanol and aggravated by inflammatory factors. The protective role of CORM-2 was abolished by SB203580 (p38 inhibitor) but not by PD98059 (ERK inhibitor) or SP600125 (JNK inhibitor). Thus, HO-1 released CO prevented ethanol-elicited hepatic oxidative damage and inflammatory stress through activating p38 MAPK pathway, suggesting a potential therapeutic role of gaseous signal molecule on ALD induced by naturally occurring phytochemicals. - Highlights: • CO alleviated ethanol-derived liver oxidative and inflammatory stress in mice. • CO eased ethanol and inflammatory factor-induced oxidative damage in hepatocytes. • The p38 MAPK is a key signaling mechanism for the protective function of CO in ALD.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Zinc ferrite nanoparticles activate IL-1b, NFKB1, CCL21 and NOS2 signaling to induce mitochondrial dependent intrinsic apoptotic pathway in WISH cells

The present study has demonstrated the translocation of zinc ferrite nanoparticles (ZnFe{sub 2}O{sub 4}-NPs) into the cytoplasm of human amnion epithelial (WISH) cells, and the ensuing cytotoxicity and genetic damage. The results suggested that in situ NPs induced oxidative stress, alterations in cellular membrane and DNA strand breaks. The [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) and neutral red uptake (NRU) cytotoxicity assays indicated 64.48 ± 1.6% and 50.73 ± 2.1% reduction in cell viability with 100 μg/ml of ZnFe{sub 2}O{sub 4}-NPs exposure. The treated WISH cells exhibited 1.2-fold higher ROS level with 0.9-fold decline in membrane potential (ΔΨm) and 7.4-fold higher DNA damage after 48 h of ZnFe{sub 2}O{sub 4}-NPs treatment. Real-time PCR (qPCR) analysis of p53, CASP 3 (caspase-3), and bax genes revealed 5.3, 1.6, and 14.9-fold upregulation, and 0.18-fold down regulation of bcl 2 gene vis-à-vis untreated control. RT{sup 2} Profiler™ PCR array data elucidated differential up-regulation of mRNA transcripts of IL-1b, NFKB1, NOS2 and CCL21 genes in the range of 1.5 to 3.7-folds. The flow cytometry based cell cycle analysis suggested the transfer of 15.2 ± 2.1% (p < 0.01) population of ZnFe{sub 2}O{sub 4}-NPs (100 μg/ml) treated cells into apoptotic phase through intrinsic pathway. Over all, the data revealed the potential of ZnFe{sub 2}O{sub 4}-NPs to induce cellular and genetic toxicity in cells of placental origin. Thus, the significant ROS production, reduction in ΔΨm, DNA damage, and activation of genes linked to inflammation, oxidative stress, proliferation, DNA damage and repair could serve as the predictive toxicity and stress markers for ecotoxicological assessment of ZnFe{sub 2}O{sub 4}-NPs induced cellular and genetic damage. - Highlights: • First report on the molecular toxicity of ZnFe{sub 2}O{sub 4}-NPs in cells of placental origin • WISH cells treated with ZnFe{sub 2}O{sub 4}-NPs exhibited cytoplasmic localization of NPs. • ZnFe{sub 2}O{sub 4}-NPs induce DNA damage and mitochondrial dysfunction in WISH cells. • ZnFe{sub 2}O{sub 4}-NPs activate inflammatory and oxidative stress signaling in WISH cells. • Elevation of p53, CASP 3, bax and bcl 2 genes affirms intrinsic apoptotic pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Ascofuranone suppresses EGF-induced HIF-1α protein synthesis by inhibition of the Akt/mTOR/p70S6K pathway in MDA-MB-231 breast cancer cells

Hypoxia-inducible factor (HIF)-1 plays an important role in tumor progression, angiogenesis and metastasis. In this study, we investigated the potential molecular mechanisms underlying the anti-angiogenic effect of ascofuranone, an isoprenoid antibiotic from Ascochyta viciae, in epidermal growth factor (EGF)-1 responsive human breast cancer cells. Ascofuranone significantly and selectively suppressed EGF-induced HIF-1α protein accumulation, whereas it did not affect the expression of HIF-1β. Furthermore, ascofuranone inhibited the transcriptional activation of vascular endothelial growth factor (VEGF) by reducing protein HIF-1α. Mechanistically, we found that the inhibitory effects of ascofuranone on HIF-1α protein expression are associated with the inhibition of synthesis HIF-1α through an EGF-dependent mechanism. In addition, ascofuranone suppressed EGF-induced phosphorylation of Akt/mTOR/p70S6 kinase, but the phosphorylation of ERK/JNK/p38 kinase was not affected by ascofuranone. These results suggest that ascofuranone suppresses EGF-induced HIF-1α protein translation through the inhibition of Akt/mTOR/p70S6 kinase signaling pathways and plays a novel role in the anti-angiogenic action. - Highlights: • Inhibitory effect of ascofuranone on HIF-1α expression is EGF-specific regulation. • Ascofuranone decreases HIF-1α protein synthesis through Akt/mTOR pathways. • Ascofuranone suppresses EGF-induced VEGF production and tumor angiogenesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Leptin induces CYP1B1 expression in MCF-7 cells through ligand-independent activation of the ERα pathway

Leptin, a hormone with multiple biological actions, is produced predominantly by adipose tissue. Among its functions, leptin can stimulate tumour cell growth. Oestrogen receptor α (ERα), which plays an essential role in breast cancer development, can be transcriptionally activated in a ligand-independent manner. In this study, we investigated the effect of leptin on CYP1B1 expression and its mechanism in breast cancer cells. Leptin induced CYP1B1 protein, messenger RNA expression and promoter activity in ERα-positive MCF-7 cells but not in ERα-negative MDA-MB-231 cells. Additionally, leptin increased 4-hydroxyoestradiol in MCF-7 cells. Also, ERα knockdown by siRNA significantly blocked the induction of CYP1B1 expression by leptin, indicating that leptin induced CYP1B1 expression via an ERα-dependent mechanism. Transient transfection with CYP1B1 deletion promoter constructs revealed that the oestrogen response element (ERE) plays important role in the up-regulation of CYP1B1 by leptin. Furthermore, leptin stimulated phosphorylation of ERα at serine residues 118 and 167 and increased ERE-luciferase activity, indicating that leptin induced CYP1B1 expression by ERα activation. Finally, we found that leptin activated ERK and Akt signalling pathways, which are upstream kinases related to ERα phosphorylation induced by leptin. Taken together, our results indicate that leptin-induced CYP1B1 expression is mediated by ligand-independent activation of the ERα pathway as a result of the activation of ERK and Akt in MCF-7 cells. - Highlights: • Leptin increased 4-hydroxyoestradiol in MCF-7 breast cancer cells. • Leptin activated ERK and Akt kinases related to ERα phosphorylation. • Leptin induces phosphorylation of ERα at serine residues 118 and 167. • Leptin induces ERE-luciferase activity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Oleanolic acid supplement attenuates liquid fructose-induced adipose tissue insulin resistance through the insulin receptor substrate-1/phosphatidylinositol 3-kinase/Akt signaling pathway in rats

Oleanolic acid, a triterpenoid contained in more than 1620 plants including various fruits and foodstuffs, has numerous metabolic effects, such as hepatoprotection. However, its underlying mechanisms remain poorly understood. Adipose tissue insulin resistance (Adipo-IR) may contribute to the development and progress of metabolic abnormalities through release of excessive free fatty acids from adipose tissue. This study investigated the effect of oleanolic acid on Adipo-IR. The results showed that supplement with oleanolic acid (25 mg/kg, once daily, by oral gavage) over 10 weeks attenuated liquid fructose-induced increase in plasma insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) index in rats. Simultaneously, oleanolic acid reversed the increase in the Adipo-IR index and plasma non-esterified fatty acid concentrations during the oral glucose tolerance test assessment. In white adipose tissue, oleanolic acid enhanced mRNA expression of the genes encoding insulin receptor, insulin receptor substrate (IRS)-1 and phosphatidylinositol 3-kinase. At the protein level, oleanolic acid upregulated total IRS-1 expression, suppressed the increased phosphorylated IRS-1 at serine-307, and restored the increased phosphorylated IRS-1 to total IRS-1 ratio. In contrast, phosphorylated Akt to total Akt ratio was increased. Furthermore, oleanolic acid reversed fructose-induced decrease in phosphorylated-Akt/Akt protein to plasma insulin concentration ratio. However, oleanolic acid did not affect IRS-2 mRNA expression. Therefore, these results suggest that oleanolic acid supplement ameliorates fructose-induced Adipo-IR in rats via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway. Our findings may provide new insights into the mechanisms of metabolic actions of oleanolic acid. - Highlights: • Adipose insulin resistance (Adipo-IR) contributes to metabolic abnormalities. • We investigated the effect of oleanolic acid (OA) on adipo-IR in fructose-fed rats. • OA attenuated fructose-induced increase in Adipo-IR index and NEFA concentrations. • OA modulated adipose IRS-1/phosphatidylinositol 3-kinase/Akt signaling. • OA ameliorates Adipo-IR via the IRS-1/PI3K/Akt signaling pathway in rats.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Dysregulation of protein degradation pathways may mediate the liver injury and phospholipidosis associated with a cationic amphiphilic antibiotic drug

A large number of antibiotics are known to cause drug-induced liver injury in the clinic; however, interpreting clinical risk is not straightforward owing to a lack of predictivity of the toxicity by standard preclinical species and a poor understanding of the mechanisms of toxicity. An example is PF-04287881, a novel ketolide antibiotic that caused elevations in liver function tests in Phase I clinical studies. In this study, a mouse diversity panel (MDP), comprised of 34 genetically diverse, inbred mouse strains, was utilized to model the toxicity observed with PF-04287881 treatment and investigate potential mechanisms that may mediate the liver response. Significant elevations in serum alanine aminotransferase (ALT) levels in PF-04287881-treated animals relative to vehicle-treated controls were observed in the majority (88%) of strains tested following a seven day exposure. The average fold elevation in ALT varied by genetic background and correlated with microscopic findings of hepatocellular hypertrophy, hepatocellular single cell necrosis, and Kupffer cell vacuolation (confirmed as phospholipidosis) in the liver. Global liver mRNA expression was evaluated in a subset of four strains to identify transcript and pathway differences that distinguish susceptible mice from resistant mice in the context of PF-04287881 treatment. The protein ubiquitination pathway was highly enriched among genes associated with PF-04287881-induced hepatocellular necrosis. Expression changes associated with PF-04287881-induced phospholipidosis included genes involved in drug transport, phospholipid metabolism, and lysosomal function. The findings suggest that perturbations in genes involved in protein degradation leading to accumulation of oxidized proteins may mediate the liver injury induced by this drug. - Highlights: • Identified susceptible and resistant mouse strains to liver injury induced by a CAD • Liver injury characterized by single cell necrosis, and phospholipidosis • Decreased gene expression associated with protein ubiquitination in sensitive mice • Altered protein ubiquitination may cause oxidized protein accumulation in the liver.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Upregulation of heme oxygenase-1 expression by dehydrodiconiferyl alcohol (DHCA) through the AMPK–Nrf2 dependent pathway

Oxidative stress is induced by the accumulation of free radicals, resulting in an imbalanced cellular redox state, which has been implicated in a variety of human diseases. Dehydrodiconiferyl alcohol (DHCA), a lignan compound isolated from Cucurbita moschata, has previously been reported to contain anti-adipogenic and anti-lipogenic effects on 3T3-L1 cells and primary MEFs (Abraham and Kappas, 2008). In this study, it was tested whether DHCA could affect the expression of HO-1, using Raw264.7 mouse macrophage cell line. DHCA increased the protein and RNA levels of HO-1 and upregulated its promoter activity. Data from transient transfection assays indicated that ARE located in the E1 region of the HO-1 promoter are important in this DHCA-mediated induction of HO-1 expression. DHCA was also shown to enhance the nuclear translocation and binding of Nrf2 to the respective DNA sequences. The upregulation of HO-1 expression by DHCA was also observed in primary macrophages derived from wild type animals, but not in those from Nrf2 KO mice. Effects of DHCA on HO-1 and Nrf2 were reduced when cells were treated with an AMPK inhibitor, Compound C, but not by PI3K/Akt or MAPK inhibitors. Data from an experiment using a specific siRNA or chemical inhibitor for HO-1 suggested that the DHCA-mediated induction of the HO-1 protein could suppress the LPS-stimulated production of NO. Taken together, our data suggest that DHCA induces the expression of HO-1 by controlling its promoter activity through the AMPK–Nrf2 pathway, eventually leading to the reduction of NO production, and may thus have potential as an effective antioxidant. - Highlights: • Dehydrodiconiferyl alcohol (DHCA) induced the expression of heme oxygenase (HO)-1. • The AMPK–Nrf2 pathway is critically involved in the DHCA-mediated induction of HO-1. • DHCA increased the expression of HO-1, Gclc and Gclm in primary macrophages. • DHCA-mediated induction of HO-1 contributed to the suppression of NO production.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Protocatechuic aldehyde ameliorates experimental pulmonary fibrosis by modulating HMGB1/RAGE pathway

An abnormal high mobility group box 1 (HMGB1) activation and a decrease in receptor for advanced glycation end-product (RAGE) play a key role in the pathogenesis of pulmonary fibrosis. Protocatechuic aldehyde (PA) is a naturally occurring compound, which is extracted from the degradation of phenolic acids. However, whether PA has anti-fibrotic functions is unknown. In this study, the effects of PA on the transforming growth factor-β1 (TGF-β1)-mediated epithelial–mesenchymal transition (EMT) in A549 cells, on the apoptosis of human type I alveolar epithelial cells (AT I), on the proliferation of human lung fibroblasts (HLF-1) in vitro, and on bleomycin (BLM)-induced pulmonary fibrosis in vivo were investigated. PA treatment resulted in a reduction of EMT in A549 cells with a decrease in vimentin and HMGB, an increase of E-cadherin and RAGE, a reduction of HLF-1 proliferation with a decrease of fibroblast growth factor 2 (FGF-2) and platelet-derived growth factor (PDGF). Apoptosis of AT I was attenuated with an increase of RAGE. PA ameliorated BLM-induced pulmonary fibrosis in rats with a reduction of histopathological scores and collagen deposition, and a lower FGF-2, PDGF, α-smooth muscle actin (α-SMA) and HMGB1 expression, whereas higher RAGE was found in BLM-instilled lungs. Through the decrease of HGMB1 and the regulation of RAGE, PA reversed the EMT, inhibited HLF-1 proliferation as well as reduced apoptosis in AT I, and prevented pulmonary fibrosis in vivo. Collectively, our results demonstrate that PA prevents experimental pulmonary fibrosis by modulating HMGB1/RAGE pathway. - Highlights: • PA prevents EMT, reduces the apoptosis of AT1 in vitro. • PA decreases proliferation of HLF-1, reduces PDGF and FGF expression in vitro. • PA prevents experimental pulmonary fibrosis by modulating the HMGB1/RAGE pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Honokiol activates the LKB1–AMPK signaling pathway and attenuates the lipid accumulation in hepatocytes

Honokiol is a bioactive neolignan compound isolated from the species of Magnolia. This study was designed to elucidate the cellular mechanism by which honokiol alleviates the development of non-alcoholic steatosis. HepG2 cells were treated with honokiol for 1 h, and then exposed to 1 mM free fatty acid (FFA) for 24 h to simulate non-alcoholic steatosis in vitro. C57BL/6 mice were fed with a high-fat diet for 28 days, and honokiol (10 mg/kg/day) was daily treated. Honokiol concentration-dependently attenuated intracellular fat overloading and triglyceride (TG) accumulation in FFA-exposed HepG2 cells. These effects were blocked by pretreatment with an AMP-activated protein kinase (AMPK) inhibitor. Honokiol significantly inhibited sterol regulatory element-binding protein-1c (SREBP-1c) maturation and the induction of lipogenic proteins, stearoyl-CoA desaturase-1 (SCD-1) and fatty acid synthase (FAS) in FFA-exposed HepG2 cells, but these effects were blocked by pretreatment of an AMPK inhibitor. Honokiol induced AMPK phosphorylation and subsequent acetyl-CoA carboxylase (ACC) phosphorylation, which were inhibited by genetic deletion of liver kinase B1 (LKB1). Honokiol stimulated LKB1 phosphorylation, and genetic deletion of LKB1 blocked the effect of honokiol on SREBP-1c maturation and the induction of SCD-1 and FAS proteins in FFA-exposed HepG2 cells. Honokiol attenuated the increases in hepatic TG and lipogenic protein levels and fat accumulation in the mice fed with high-fat diet, while significantly induced LKB1 and AMPK phosphorylation. Taken together, our findings suggest that honokiol has an anti-lipogenic effect in hepatocytes, and this effect may be mediated by the LKB1–AMPK signaling pathway, which induces ACC phosphorylation and inhibits SREBP-1c maturation in hepatocytes. - Highlights: • Honokiol attenuates lipid accumulation induced by free fatty acid in hepatocyte. • Honokiol inhibits the increase in lipogenic enzyme levels induced by free fatty acid. • Honokiol induces the phosphorylation of AMPK and ACC and inhibits SREBP-1c maturation. • LKB1–AMPK signaling pathway mediates anti-lipogenic effect of honokiol in hepatocyte. • Honokiol activates LKB1 and AMPK and inhibits nonalcoholic steatosis in HFD-fed mice.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Selenite exacerbates hepatic insulin resistance in mouse model of type 2 diabetes through oxidative stress-mediated JNK pathway

Recent evidence suggests a potential pro-diabetic effect of selenite treatment in type 2 diabetics; however, the underlying mechanisms remain elusive. Here we investigated the effects and the underlying mechanisms of selenite treatment in a nongenetic mouse model of type 2 diabetes. High-fat diet (HFD)/streptozotocin (STZ)-induced diabetic mice were orally gavaged with selenite at 0.5 or 2.0 mg/kg body weight/day or vehicle for 4 weeks. High-dose selenite treatment significantly elevated fasting plasma insulin levels and insulin resistance index, in parallel with impaired glucose tolerance, insulin tolerance and pyruvate tolerance. High-dose selenite treatment also attenuated hepatic IRS1/Akt/FoxO1 signaling and pyruvate kinase gene expressions, but elevated the gene expressions of phosphoenolpyruvate carboxyl kinase (PEPCK), glucose 6-phosphatase (G6Pase), peroxisomal proliferator-activated receptor-γ coactivator 1α (PGC-1α) and selenoprotein P (SelP) in the liver. Furthermore, high-dose selenite treatment caused significant increases in MDA contents, protein carbonyl contents, and a decrease in GSH/GSSG ratio in the liver, concurrent with enhanced ASK1/MKK4/JNK signaling. Taken together, these findings suggest that high-dose selenite treatment exacerbates hepatic insulin resistance in mouse model of type 2 diabetes, at least in part through oxidative stress-mediated JNK pathway, providing new mechanistic insights into the pro-diabetic effect of selenite in type 2 diabetes. - Highlights: • Selenite exacerbates hepatic insulin resistance in HFD/STZ-induced diabetic mice. • Selenite elevates hepatic gluconeogenesis and reduces glycolysis in diabetic mice. • Selenite exacerbates hepatic oxidative stress and triggers JNK signaling pathway. • Selenite elevates hepatic selenoprotein P expression in diabetic mice.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

H{sub 2}S induces vasoconstriction of rat cerebral arteries via cAMP/adenylyl cyclase pathway

Hydrogen sulfide (H{sub 2}S), traditionally known for its toxic effects, is now involved in regulating vascular tone. Here we investigated the vasoconstrictive effect of H{sub 2}S on cerebral artery and the underlying mechanism. Sodium hydrosulfide (NaHS), a donor of H{sub 2}S, concentration-dependently induced vasoconstriction on basilar artery, which was enhanced in the presence of isoprenaline, a β-adrenoceptor agonist or forskolin, an adenylyl cyclase activator. Administration of NaHS attenuated the vasorelaxant effects of isoprenaline or forskolin. Meanwhile, the NaHS-induced vasoconstriction was diminished in the presence of 8B-cAMP, an analog of cAMP, but was not affected by Bay K-8644, a selective L-type Ca{sup 2+} channel agonist. These results could be explained by the revised effects of NaHS on isoprenaline-induced cAMP elevation and forskolin-stimulated adenylyl cyclase activity. Additionally, NaHS-induced vasoconstriction was enhanced by removing the endothelium or in the presence of L-NAME, an inhibitor of nitric oxide synthase. L-NAME only partially attenuated the effect of NaHS which was given together with forskolin on the pre-contracted artery. In conclusion, H{sub 2}S induces vasoconstriction of cerebral artery via, at least in part, cAMP/adenylyl cyclase pathway. - Highlights: • The vasoactivity effect of NaHS, a donor of H{sub 2}S, was studied on rat cerebral arteries. • H{sub 2}S induces a constriction, not a relaxant effect on basilar arteries. • The vasoconstrictive effect is invovled in inhibiting adenylyl cyclase to reduce cAMP levels. • The vasoconstriction is partially antagonized by NO, and does not necessarily act via NO pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Ghrelin protects against depleted uranium-induced apoptosis of MC3T3-E1 cells through oxidative stress-mediated p38-mitogen-activated protein kinase pathway

Depleted uranium (DU) mainly accumulates in the bone over the long term. Osteoblast cells are responsible for the formation of bone, and they are sensitive to DU damage. However, studies investigating methods of reducing DU damage in osteoblasts are rarely reported. Ghrelin is a stomach hormone that stimulates growth hormones released from the hypothalamic–pituitary axis, and it is believed to play an important physiological role in bone metabolism. This study evaluates the impact of ghrelin on DU-induced apoptosis of the osteoblast MC3T3-E1 and investigates its underlying mechanisms. The results show that ghrelin relieved the intracellular oxidative stress induced by DU, eliminated reactive oxygen species (ROS) and reduced lipid peroxidation by increasing intracellular GSH levels; in addition, ghrelin effectively suppressed apoptosis, enhanced mitochondrial membrane potential, and inhibited cytochrome c release and caspase-3 activation after DU exposure. Moreover, ghrelin significantly reduced the expression of DU-induced phosphorylated p38-mitogen-activated protein kinase (MAPK). A specific inhibitor (SB203580) or specific siRNA of p38-MAPK could significantly suppress DU-induced apoptosis and related signals, whereas ROS production was not affected. In addition, ghrelin receptor inhibition could reduce the anti-apoptosis effect of ghrelin on DU and reverse the effect of ghrelin on intracellular ROS and p38-MAPK after DU exposure. These results suggest that ghrelin can suppress DU-induced apoptosis of MC3T3-E1 cells, reduce DU-induced oxidative stress by interacting with its receptor, and inhibit downstream p38-MAPK activation, thereby suppressing the mitochondrial-dependent apoptosis pathway. - Highlights: • Ghrelin suppressed DU-induced apoptosis of MC3T3-E1 cells. • Ghrelin inhibited DU-induced oxidative stress and further p38-MAPK activation. • Ghrelin further suppressed mitochondrial-dependent apoptosis pathway. • The anti-oxidation effect of ghrelin was regulated through its receptor. • Ghrelin has the potential for use in drug therapies for DU poisoning.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Fibroblast growth factor 21 attenuates hepatic fibrogenesis through TGF-β/smad2/3 and NF-κB signaling pathways

Fibroblast growth factor 21 (FGF-21) is a secreted protein, which has anti-diabetic and lipocaic effects, but its ability to protect against hepatic fibrosis has not been studied. In this study, we investigated the ability of FGF-21 to attenuate dimethylnitrosamine (DMN)-induced hepatic fibrogenesis in mice and the mechanism of its action. Hepatic fibrosis was induced by injection of DMN, FGF-21 was administered to the mice once daily in association with DMN injection till the end of the experiment. Histopathological examination, tissue 4-hydroxyproline content and expressions of smooth muscle α-actin (α-SMA) and collagen I were measured to assess hepatic fibrosis. Ethanol/PDGF-BB-activated hepatic stellate cells (HSCs) were used to understand the mechanisms of FGF-21 inhibited hepatic fibrogenesis. Results showed that FGF-21 treatment attenuated hepatic fibrogenesis and was associated with a significant decrease in intrahepatic fibrogenesis, 4-hydroxyproline accumulation, α-SMA expression and collagen I deposition. FGF-21 treatment inhibited the activation of HSCs via down-regulating the expression of TGF-β, NF-κB nuclear translocation, phosphorylation levels of smad2/3 and IκBα. Besides, FGF-21 treatment caused activated HSC apoptosis with increasing expression of Caspase-3, and decreased the ratio of Bcl-2 to Bax. In conclusion, FGF-21 attenuates hepatic fibrogenesis and inhibits the activation of HSC warranting the use of FGF-21 as a potential therapeutic agent in the treatment of hepatic fibrosis. - Highlights: • Fibroblast growth factor 21 attenuates hepatic fibrogenesis. • Fibroblast growth factor 21 attenuates hepatic fibrogenesis via TGF-β/smad2/3 signaling pathways. • Fibroblast growth factor 21 attenuates hepatic fibrogenesis via NF-κB signaling pathways.

60 APPLIED LIFE SCIENCES↗