Ching Shu Lai

Rosmanol Potently Inhibits Lipopolysaccharide-Induced iNOS and COX-2 Expression through Downregulating MAPK, NF-κB, STAT3 and C/EBP Signaling Pathways

Rosmanol is a natural polyphenol from the herb rosemary (Rosmarinus officinalis L.) with high antioxidant activity. In this study, we investigated the inhibitory effects of rosmanol on the induction of NO synthase (NOS) and COX-2 in RAW 264.7 cells induced by lipopolysaccharide (LPS). Rosmanol markedly inhibited LPS-stimulated iNOS and COX-2 protein and gene expression, as well as the downstream products, NO and PGE2. Treatment with rosmanol also reduced translocation of the nuclear factor-kappaB (NF-kappaB) subunits by prevention of the degradation and phosphorylation of inhibitor kappaB (IkappaB). Western blot analysis showed that rosmanol significantly inhibited translocation and phosphorylation of NF-kappaB, signal transducer and activator of transcription-3 (STAT3), and the protein expression of C/EBPbeta and C/EBPdelta. We also found that rosmanol suppressed LPS-induced phosphorylation of ERK1/2, p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling. Our results demonstrate that rosmanol downregulates inflammatory iNOS and COX-2 gene expression by inhibiting the activation of NF-kappaB and STAT3 through interfering with the activation of PI3K/Akt and MAPK signaling. Taken together, rosmanol might contribute to the potent anti-inflammatory effect of rosemary and may have potential to be developed into an effective anti-inflammatory agent.

Xanthigen Suppresses Preadipocyte Differentiation and Adipogenesis through Down-regulation of PPARγ and C/EBPs and Modulation of SIRT-1, AMPK, and FoxO Pathways

Xanthigen is a source of punicic acid and fucoxanthin derived from pomegranate seed and brown seaweed, respectively with recognized triacylglycerol-lowering effects in humans, yet the mechanism remains to be fully elucidated. The present study investigated the inhibitory effects of Xanthigen, fucoxanthin, and punicic acid (70% in pomegranate seed oil) on the differentiation of 3T3-L1 preadipocytes. Xanthigen potently and dose-dependently suppressed accumulation of lipid droplets in adipocytes compared to its individual components, fucoxanthin and pomegranate seed oil. Western blot analysis revealed that Xanthigen markedly down-regulated the protein levels of key adipogenesis transcription factors peroxisome proliferator-activated receptor (PPAR)γ, CCAAT/enhancer binding protein (C/EBP) β, and C/EBPδ as well as a key enzyme involved in adipogenesis, fatty acid synthase (FAS). Xanthigen up-regulated the NAD(+)-dependent histone deacetylases (SIRT1) and activated AMP-activated protein kinase (AMPK) signaling in differentiated 3T3-L1 adipocytes. In addition, Xanthigen may also stimulate insulin trigger signaling and result in Akt-dependent phosphorylation of forkhead/winged helix O (FoxO)1 and FoxO3a. These results indicate that Xanthigen suppresses adipocyte differentiation and lipid accumulation through multiple mechanisms and may have applications for the treatment of obesity.

Hexavalent chromium induced ROS formation, Akt, NF-κB, and MAPK activation, and TNF-α and IL-1α production in keratinocytes

In certain cell types, it has been found that, hexavalent chromium could increase ROS formation, activate cell signaling and stimulate the release of cytokines. But, in keratinocytes, these effects have not yet fully been demonstrated. Our aim is to observe the above effects of hexavalent chromium on keratinocytes. By utilizing HaCaT cells and the skin of albino guinea pigs, we showed that hexavalent chromium could increase ROS formation, activate the Akt, NF-kB, and MAPK pathways as well as increase the production of cytokines, including TNF-alpha and IL-1alpha. The release of these cytokines from keratinocytes is considered to be a key participant in the pathogenesis of contact hypersensitivity. Among cement workers, chromium hypersensitivity is an important occupational skin disease issue. Therefore, the observations of our study help us better understand the role of hexavalent chromium on the development of chromium hypersensitivity, which might provide clues for clinicians in the development of chemopreventative agents for the prevention of chromium hypersensitivity among cement workers.

Chemopreventative effects of tetrahydrocurcumin on human diseases

Chemoprevention is a relatively new and promising strategy to prevent human degenerative diseases, including cancer, and is defined as the use of natural dietary compounds and/or synthetic substances to block, inhibit, reverse, or retard the progress of human diseases. Tetrahydrocurcumin (THC) is a major metabolite of curcumin (extracted from the roots of the Curcuma longa Linn). THC has been demonstrated to prevent oxidative stress and inflammation, to act against neurodegeneration, and to possess anti-cancer activity. In this review, we summarize the current knowledge and underlying molecular mechanisms of the chemopreventative activities of THC and its potential effects on the development of various human diseases.

Combination treatment with arsenic trioxide and irradiation enhances apoptotic effects in U937 cells through increased mitotic arrest and ROS generation.

Arsenic compounds have been used as anti-cancer agents in traditional Chinese medicine. Ionizing radiation (IR) is one of the most effective tools in the clinical treatment of cancer. The induction of apoptotic cell death is a significant mechanism of tumor cells under the influence of radio-/chemotherapy, and resistance to these treatments has been linked to some cancer cell lines with a low propensity for apoptosis. A combination of different anti-tumoral treatment modalities is advantageous in limiting non-specific toxicity often observed by an exceedingly high dose of single regimen. The present study aimed at investigating the enhanced effects and mechanisms in cell cycle distribution and apoptosis of U937 cells, a human pre-monocytic leukemia cell line lacking functional p53 protein, after combination treatment with irradiation and As(2)O(3). Our results indicated that combined treatment led to activation of cdc-2, which is related to the expression of cyclin B. In addition, combined treatment increased apoptotic cell death in U937 cells, which is correlated with the induction of mitotic arrest, the increase in intracellular reactive oxygen species (ROS) generation, the decrease in B-cell leukemia/lymphoma 2 (Bcl-2) and B-cell leukemia/lymphoma XL (Bcl-XL) levels, the loss of mitochondria membrane potential, and the activation of caspase-3. We found that combining radiation and As(2)O(3) may be an effective strategy against p53-deficient leukemia cells.

Potent Anti-Cancer Effect of 3′-Hydroxypterostilbene in Human Colon Xenograft Tumors

Here we report that 3′-hydroxypterostilbene (HPSB), a natural pterostilbene analogue, was more potent than pterostilbene against the growth of human cancer cells (COLO 205, HCT-116, and HT-29) with measured IC50 values of 9.0, 40.2, and 70.9 µM, respectively. We found that HPSB effectively inhibited the growth of human colon cancer cells by inducing apoptosis and autophagy. Autophagy occurred at an early stage and was observed through the formation of acidic vesicular organelles and microtubule-associated protein 1 light chain 3-II production. At the molecular levels, the results from western blot analysis showed that HPSB significantly down-regulated phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs) signalings including decreased the phosphorylation of mammalian target of rapamycin (mTOR). Significant therapeutic effects were demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with HPSB (10 mg/kg i.p.). These inhibitory effects were accompanied by mechanistic down-regulation of the protein levels of cyclooxygenase-2 (COX-2), matrix metallopeptidase-9 (MMP-9), vascular endothelial growth factor (VEGF), and cyclin D1, as well as by the induction of apoptosis in colon tumors. Our findings suggest that HPSB could serve as a novel promising agent for colon cancer treatment.

Differential inhibitory effects of inotilone on inflammatory mediators, inducible nitric oxide synthase and cyclooxygenase‐2, in LPS‐stimulated murine macrophage

The inhibitory effects of inotilone and methylinotilone on the induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in murine RAW 264.7 cells activated with LPS were investigated. The results show that both hydroxyl groups on the benzene ring of the inotilone molecule are required for better anti-inflammatory effect. Western blotting and RT-PCR analyses demonstrated that inotilone blocked protein and mRNA expression of iNOS but not COX-2. Instead, inotilone inhibited prostaglandin E(2) production through decreasing the enzyme activity of COX-2. The repression of iNOS but not COX-2 expression may come from the differential effect of inotilone on nuclear factor-kappaB (NFkappaB) and CCAAT/enhancer-binding protein beta Treatment with inotilone resulted in the reduction of LPS-induced nuclear translocation of NFkappaB subunit and the NFkappaB-dependent transcriptional activity by blocking phosphorylation of inhibitor kappaB(IkappaB)alpha and p65 and subsequent degradation of inhibitor kappaBalpha. Inotilone also inhibited LPS-induced activation of PI3K/Akt and extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase. Our results suggest that inotilone may have potential to be developed into an effective anti-inflammatory agent.

Hexahydro-β-acids potently inhibit 12-O-tetradecanoylphorbol 13-acetate-induced skin inflammation and tumor promotion in mice.

We previously reported that hexahydro-beta-acids (HBAs), reduced derivatives of beta-acids (BA) from hop (Humulus lupulus L.), displayed more potent anti-inflammatory activity than BA in lipopolysaccharide-stimulated murine macrophages. In this study, we investigated the effects and underlying molecular mechanisms of hexahydro-β-acids (HBAs) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated mouse skin inflammation and in the two-stage carcinogenesis model. Female ICR mice pretreated with HBA at 1 and 10 μg significantly reduced ear edema, epidermal hyperplasia, and infiltration of inflammatory cells caused by TPA. Molecular analysis exhibited that HBA suppressed iNOS, COX-2, and ornithine decarboxylase (ODC) protein and gene expression through interfering with mitogen-activated protein kinases (MAPKs) and phosphatidylinositiol 3-kinase (PI3K)/Akt signaling as well as the activation of transcription factor NF-κB. Furthermore, application of HBA (1 and 10 μg) prior to each TPA treatment (17.2 ± 0.9 tumors/mouse) resulted in the significant reduction of tumor multiplicity (5.1 ± 1.2, P < 0.01 and 2.3 ± 1.2, P < 0.001, respectively) in 7,12-dimethyl-benzanthracene (DMBA)-initiated mouse skin. The tumor incidence was significantly lowered to 75% (P < 0.05) and 58.7% (P < 0.01) by HBA pretreatment, respectively, and significantly reduced the tumor weight (0.34 ± 0.14 g, P < 0.01 and 0.09 ± 0.10 g, P < 0.001, respectively) as compared to DMBA/TPA-induced tumors (0.76 ± 0.04 g).

Se-Methyl-L-selenocysteine Induces Apoptosis via Endoplasmic Reticulum Stress and the Death Receptor Pathway in Human Colon Adenocarcinoma COLO 205 Cells.

Selenomethionine (SeMet) and Se-methyl-L-selenocysteine (MSeC) are natural organoselenium compounds found in garlic, onion, and broccoli. In addition, these compounds have lower toxicity and better anticancer activities than inorganic Se. This study investigated the effects of MSeC treatment on the growth of COLO 205 human colorectal adenocarcinoma cells and evaluated the mechanisms related to the MSeC-induced effects. When COLO 205 cells were treated with 200 μM MSeC for 24 h, MSeC caused 80% apoptosis in cells. MSeC increased the expression of Fas and FasL, followed by the cleavage of caspase-3, caspase-8, DNA fragmentation factor (DFF45), and poly(ADP-ribose) polymerase (PARP). MSeC also increased the levels of Bax protein and decreased the levels of Bid and Bcl-2 proteins. However, MSeC did not cause apoptosis through reactive oxygen species (ROS) stress but instead through endoplasmic reticulum (ER) stress. The cleavage of caspase-12 and caspase-9 was shown to increase the growth arrest and protein levels of DNA-damage inducible genes (GADD) 153 and 45. MSeC also downregulated the ERK1/2 and PI3K/AKT protein levels and upregulated the p38 and JNK protein levels in COLO 205 cells. These results showed that the mechanism by which MSeC induced apoptosis in COLO 205 cells involved caspase activation, the extrinsic apoptotic pathway, and the regulation of ER-stress-induced apoptosis.

Chemopreventive effect of natural dietary compounds on xenobiotic-induced toxicity

Contaminants (or pollutants) that affect human health have become an important issue, spawning a myriad of studies on how to prevent harmful contaminant-induced effects. Recently, a variety of biological functions of natural dietary compounds derived from consumed foods and plants have been demonstrated in a number of studies. Natural dietary compounds exhibited several beneficial effects for the prevention of disease and the inhibition of chemically-induced carcinogenesis. Contaminant-induced toxicity and carcinogenesis are mostly attributed to the mutagenic activity of reactive metabolites and the disruption of normal biological functions. Therefore, the metabolic regulation of hazardous chemicals is key to reducing contaminant-induced adverse health effects. Moreover, promoting contaminant excretion from the body through Phase I and II metabolizing enzymes is also a useful strategy for reducing contaminant-induced toxicity. This review focuses on summarizing the natural dietary compounds derived from common dietary foods and plants and their possible mechanisms of action in the prevention/suppression of contaminant-induced toxicity.