Cadmium-associated protein changes in residents of contaminated areas: Abandoned mine and smelter.

Cadmium (Cd), a serious environmental contaminant, is associated with adverse health effects. However, the specific changes that the human body experiences in response to exposure to varying concentrations of cadmium remain unknown. The high levels of heavy metal contamination, especially Cd, in abandoned mines and smelter sites make them ideal locations to investigate the physiological manifestations of Cd exposure. This study found that individuals inhabiting abandoned mine and smelter areas had higher concentrations of Cd in their urine and blood compared to those living outside these areas (i.e., the controls). Furthermore, proteomic profiling of blood samples from all study groups was performed to identify proteomic biomarkers associated with chronic and severe Cd exposure. This analysis showed statistically significant correlations between urine Cd levels and sixteen proteins. Among these proteins, seven exhibited significantly altered expressions in samples from contaminated areas compared with those from control areas. Therefore, these proteins were selected as potential markers representing Cd-related protein alterations. Multiple reaction monitoring analysis was performed to validate the expression patterns of the proteins and four proteins were found to exhibit consistent trends. The findings show that Cd exposure significantly affects the expression of certain proteins in the human body. Understanding the underlying mechanisms and diseases associated with Cd-induced protein alterations can aid in the development of effective preventive and therapeutic strategies for individuals exposed to Cd-linked pollution.

Bioaccumulation of Lead, Cadmium, and Arsenic in a Mining Area and Its Associated Health Effects.

Soil contamination is associated with a high potential for health issues. This study aimed to investigate the bioaccumulation of heavy metals and its associated health impact among residents near a mining area. We performed environmental monitoring by analyzing lead (Pb), cadmium (Cd), and arsenic (As) levels in soil and rice samples, as well as biomonitoring by analyzing blood and urine samples from 58 residents living near the mine. Additionally, concentration trends were investigated among 26 participants in a 2013 study. The Cd and As levels in the soil samples and Cd levels in the rice samples exceeded the criteria for concern. The geometric mean blood Cd level (2.12 µg/L) was two times higher than that in the general population aged > 40 years. The blood Cd level showed decreasing trends from the previous measurements of 4.56-2.25 µg/L, but was still higher than that in the general population. The blood and urine Cd levels were higher in those with a low estimated glomerular filtration rate (eGFR) than in those with normal eGFR. In conclusion, heavy metals from mining areas can accumulate in soil and rice, adversely impacting human health. Continuous environmental monitoring and biomonitoring are required to ensure the safety of residents.

In Silico Prospecting for Novel Bioactive Peptides from Seafoods: A Case Study on Pacific Oyster (Crassostrea gigas).

Pacific oyster (Crassostrea gigas), an abundant bivalve consumed across the Pacific, is known to possess a wide range of bioactivities. While there has been some work on its bioactive hydrolysates, the discovery of bioactive peptides (BAPs) remains limited due to the resource-intensive nature of the existing discovery pipeline. To overcome this constraint, in silico-based prospecting is employed to accelerate BAP discovery. Major oyster proteins were digested virtually under a simulated gastrointestinal condition to generate virtual peptide products that were screened against existing databases for peptide bioactivities, toxicity, bitterness, stability in the intestine and in the blood, and novelty. Five peptide candidates were shortlisted showing antidiabetic, anti-inflammatory, antihypertensive, antimicrobial, and anticancer potential. By employing this approach, oyster BAPs were identified at a faster rate, with a wider applicability reach. With the growing market for peptide-based nutraceuticals, this provides an efficient workflow for candidate scouting and end-use investigation for targeted functional product preparation.

Fish and Shellfish-Derived Anti-Inflammatory Protein Products: Properties and Mechanisms.

The interest in utilizing food-derived compounds therapeutically has been rising. With the growing prevalence of systematic chronic inflammation (SCI), efforts to find treatments that do not result in the side effects of current anti-inflammatory drugs are underway. Bioactive peptides (BAPs) are a particularly promising class of compounds for the treatment of SCI, and the abundance of high-quality seafood processing byproducts (SPB) makes it a favorable material to derive anti-inflammatory BAPs. Recent research into the structural properties of anti-inflammatory BAPs has found a few key tendencies including they tend to be short and of low molecular weight (LMW), have an overall positive charge, contain hydrophobic amino acids (AAs), and be rich in radical scavenging AAs. SPB-derived anti-inflammatory BAPs have been observed to work via inhibition of the NF-κB and MAPK pathways by disrupting the phosphorylation of IκBα and one or more kinases (ERK, JNK, and p38), respectively. Radical scavenging capacity has also been shown to play a significant role in the efficacy of SPB-derived anti-inflammatory BAPs. To determine if SPB-derived BAPs can serve as an effective treatment for SCI it will be important to understand their properties and mechanisms of action, and this review highlights such findings in recent research.

Therapeutic Potential of Tuna Backbone Peptide and Its Analogs: An In Vitro and In Silico Study.

Tuna backbone peptide (TBP) has been reported to exert potent inhibitory activity against lipid peroxidation in vitro. Since this bears relevant physiological implications, this study was undertaken to assess the impact of peptide modifications on its bioactivity and other therapeutic potential using in vitro and in silico approach. Some TBP analogs, despite lower purity than the parent peptide, exerted promising antioxidant activities in vitro demonstrated by ABTS radical scavenging assay and cellular antioxidant activity assay. In silico digestion of the peptides resulted in the generation of antioxidant, angiotensin-converting enzyme (ACE), and dipeptidyl peptidase-IV (DPPIV) inhibitory dipeptides. Using bioinformatics platforms, we found five stable TBP analogs that hold therapeutic potential with their predicted multifunctionality, stability, non-toxicity, and low bitterness intensity. This work shows how screening and prospecting for bioactive peptides can be improved with the use of in vitro and in silico approaches.

Endoplasmic reticulum chaperone GRP78 regulates macrophage function and insulin resistance in diet-induced obesity.

Obesity-mediated inflammation is a major cause of insulin resistance, and macrophages play an important role in this process. The 78-kDa glucose-regulated protein (GRP78) is a major endoplasmic reticulum chaperone that modulates unfolded protein response (UPR), and mice with GRP78 heterozygosity were resistant to diet-induced obesity. Here, we show that mice with macrophage-selective ablation of GRP78 (Lyz- GRP78-/-) are protected from skeletal muscle insulin resistance without changes in obesity compared with wild-type mice after 9 wk of high-fat diet. GRP78-deficient macrophages demonstrated adapted UPR with up-regulation of activating transcription factor (ATF)-4 and M2-polarization markers. Diet-induced adipose tissue inflammation was reduced, and bone marrow-derived macrophages from Lyz- GRP78-/- mice demonstrated a selective increase in IL-6 expression. Serum IL-13 levels were elevated by >4-fold in Lyz- GRP78-/- mice, and IL-6 stimulated the myocyte expression of IL-13 and IL-13 receptor. Lastly, recombinant IL-13 acutely increased glucose metabolism in Lyz- GRP78-/- mice. Taken together, our data indicate that GRP78 deficiency activates UPR by increasing ATF-4, and promotes M2-polarization of macrophages with a selective increase in IL-6 secretion. Macrophage-derived IL-6 stimulates the myocyte expression of IL-13 and regulates muscle glucose metabolism in a paracrine manner. Thus, our findings identify a novel crosstalk between macrophages and skeletal muscle in the modulation of obesity-mediated insulin resistance.-Kim, J. H., Lee, E., Friedline, R. H., Suk, S., Jung, D. Y., Dagdeviren, S., Hu, X., Inashima, K., Noh, H. L., Kwon, J. Y., Nambu, A., Huh, J. R., Han, M. S., Davis, R. J., Lee, A. S., Lee, K. W., Kim, J. K. Endoplasmic reticulum chaperone GRP78 regulates macrophage function and insulin resistance in diet-induced obesity.

Gingerenone A, a polyphenol present in ginger, suppresses obesity and adipose tissue inflammation in high-fat diet-fed mice.

SCOPE: Ginger exerts protective effects on obesity and its complications. Our objectives here are to identify bioactive compounds that inhibit adipogenesis and lipid accumulation in vitro, elucidate the anti-obesity effect of gingerenone A (GA) in diet-induced obesity (DIO), and investigate whether GA affects adipose tissue inflammation (ATI). METHODS AND RESULTS: Oil red O staining showed that GA had the most potent inhibitory effect on adipogenesis and lipid accumulation in 3T3-L1 cells among ginger components tested at a single concentration (40 µM). Consistent with in vitro data, GA attenuates DIO by reducing fat mass in mice. This was accompanied by a modulation of fatty acid metabolism via activation of AMP-activated protein kinase (AMPK) in vitro and in vivo. Additionally, GA suppressed ATI by inhibiting macrophage recruitment and downregulating pro-inflammatory cytokines. CONCLUSION: These results suggest that GA may be used as a potential therapeutic candidate for the treatment of obesity and its complications by suppressing adipose expansion and inflammation.

Theobroma cacao extract attenuates the development of Dermatophagoides farinae-induced atopic dermatitis-like symptoms in NC/Nga mice.

Cacao beans from Theobroma cacao are an abundant source of polyphenols, particularly flavonoids. Previous studies demonstrated that cacao flavanols decrease pro-inflammatory cytokines resulting in the alleviation of allergic symptoms. We sought to investigate the effects of cacao extract (CE) on Dermatophagoides farinae extract (DFE)-induced atopic dermatitis (AD)-like symptoms. CE attenuated DFE-induced AD-like symptoms as assessed by skin lesion analyses, dermatitis score, and skin thickness. Histopathological analysis revealed that CE suppressed DFE-induced immune cell infiltration into the skin. These observations occurred concomitantly with the downregulation of inflammatory markers including serum immunoglobulin (Ig) E, chemokine; thymus and activation-regulated chemokine and macrophage-derived chemokine as well as the skin-derived cytokines interleukin (IL)-4, IL-5, and interferon-γ. CE also significantly alleviated transepidermal water loss and increased skin hydration. These results suggest that CE, a natural phytochemical-rich food, has potential therapeutic efficacy for the treatment of AD.

Molecular mechanisms of green tea polyphenols with protective effects against skin photoaging.

Whereas green tea has historically been consumed in high quantities in Northeast Asia, its popularity is also increasing in many Western countries. Green tea is an abundant source of plant polyphenols exhibiting numerous effects that are potentially beneficial for human health. Accumulating evidence suggests that green tea polyphenols confer protective effects on the skin against ultraviolet (UV) irradiation-induced acceleration of skin aging, involving antimelanogenic, antiwrinkle, antioxidant, and anti-inflammatory effects as well as prevention of immunosuppression. Melanin pigmentation in the skin is a major defense mechanism against UV irradiation, but pigmentation abnormalities such as melasma, freckles, senile lentigines, and other forms of melanin hyperpigmentation can also cause serious health and aesthetic issues. Furthermore, UV irradiation initiates the degradation of fibrillar collagen and elastic fibers, promoting the process of skin aging through deep wrinkle formation and loss of tissue elasticity. UV irradiation-induced formation of free radicals also contributes to accelerated photoaging. Additionally, immunosuppression caused by UV irradiation plays an important role in photoaging and skin carcinogenesis. In this review, we summarize the current literature regarding the antimelanogenic, antiwrinkle, antioxidant, and immunosuppression preventive mechanisms of green tea polyphenols that have been demonstrated to protect against UV irradiation-stimulated skin photoaging, and gauge the quality of evidence supporting the need for clinical studies using green tea polyphenols as anti-photoaging agents in novel cosmeceuticals.

Methionine deprivation suppresses triple-negative breast cancer metastasis in vitro and in vivo.

Nutrient deprivation strategies have been proposed as an adjuvant therapy for cancer cells due to their increased metabolic demand. We examined the specific inhibitory effects of amino acid deprivation on the metastatic phenotypes of the human triple-negative breast cancer (TNBC) cell lines MDA-MB-231 and Hs 578T, as well as the orthotopic 4T1 mouse TNBC tumor model. Among the 10 essential amino acids tested, methionine deprivation elicited the strongest inhibitory effects on the migration and invasion of these cancer cells. Methionine deprivation reduced the phosphorylation of focal adhesion kinase, as well as the activity and mRNA expression of matrix metalloproteinases MMP-2 and MMP-9, two major markers of metastasis, while increasing the mRNA expression of tissue inhibitor of metalloproteinase 1 in MDA-MB-231 cells. Furthermore, methionine restriction downregulated the metastasis-related factor urokinase plasminogen activatior and upregulated plasminogen activator inhibitor 1 mRNA expression. Animals on the methionine-deprived diet showed lower lung metastasis rates compared to mice on the control diet. Taken together, these results suggest that methionine restriction could provide a potential nutritional strategy for more effective cancer therapy.

Brown Pine Leaf Extract and Its Active Component Trans-Communic Acid Inhibit UVB-Induced MMP-1 Expression by Targeting PI3K.

Japanese red pine (Pinus densiflora) is widely present in China, Japan, and Korea. Its green pine leaves have traditionally been used as a food as well as a coloring agent. After being shed, pine leaves change their color from green to brown within two years, and although the brown pine leaves are abundantly available, their value has not been closely assessed. In this study, we investigated the potential anti-photoaging properties of brown pine leaves for skin. Brown pine leaf extract (BPLE) inhibited UVB-induced matrix metalloproteinase-1 (MMP-1) expression to a greater extent than pine leaf extract (PLE) in human keratinocytes and a human skin equivalent model. HPLC analysis revealed that the quantity of trans-communic acid (TCA) and dehydroabietic acid (DAA) significantly increases when the pine leaf color changes from green to brown. BPLE and TCA elicited reductions in UVB-induced MMP-1 mRNA expression and activator protein-1 (AP-1) transactivation by reducing DNA binding activity of phospho-c-Jun, c-fos and Fra-1. BPLE and TCA also inhibited UVB-induced Akt phosphorylation, but not mitogen activated protein kinase (MAPK), known regulators of AP-1 transactivation. We additionally found that BPLE and TCA inhibited phosphoinositide 3-kinase (PI3K), the upstream kinase of Akt, in vitro. In summary, both BPLE and its active component TCA exhibit protective effects against UVB-induced skin aging. Taken together, these findings underline the potential for BPLE and TCA to be utilized as anti-wrinkling agents and cosmetic ingredients, as they suppress UVB-induced MMP-1 expression.

20-O-ß-D-glucopyranosyl-20(S)-protopanaxadiol, a metabolite of ginsenoside Rb1, enhances the production of hyaluronic acid through the activation of ERK and Akt mediated by Src tyrosin kinase in human keratinocytes.

The aim of the present study was to determine the mechanisms through which 20-O-ß-D-glucopyranosyl-20(S)-protopanaxadiol (20GPPD) promotes the production of hyaluronic acid (HA) in human keratinocytes. 20GPPD is the primary bioactive metabolite of Rb1, a major ginsenoside found in ginseng (Panax ginseng). We sought to elucidate the underlying mechanisms behind the 20GPPD-induced production of HA. We found that 20GPPD induced an increase in HA production by elevating hyaluronan synthase 2 (HAS2) expression in human keratinocytes. The phosphorylation of extracellular signal-regulated kinase (ERK) and Akt was also enhanced by 20GPPD in a dose-dependent manner. The pharmacological inhibition of ERK (using U0126) or Akt (using LY294002) suppressed the 20GPPD-induced expression of HAS2, whereas treatment with an epidermal growth factor receptor (EGFR) inhibitor (AG1478) or an intracellular Ca2+ chelator (BAPTA/AM) did not exert any observable effects. The increased Src phosphorylation was also confirmed following treatment with 20GPPD in the human keratinocytes. Following pre-treatment with the Src inhibitor, PP2, both HA production and HAS2 expression were attenuated. Furthermore, the 20GPPD-enhanced ERK and Akt signaling decreased following treatment with PP2. Taken together, our results suggest that Src kinase plays a critical role in the 20GPPD-induced production of HA by acting as an upstream modulator of ERK and Akt activity in human keratinocytes.

Caffeic acid phenethyl ester, a major component of propolis, suppresses high fat diet-induced obesity through inhibiting adipogenesis at the mitotic clonal expansion stage.

In the present study, we aimed to investigate the antiobesity effect of CAPE in vivo, and the mechanism by which CAPE regulates body weight in vitro. To confirm the antiobesity effect of CAPE in vivo, mice were fed with a high fat diet (HFD) with different concentrations of CAPE for 5 weeks. CAPE significantly reduced body weight gain and epididymal fat mass in obese mice fed a HFD. In accordance with in vivo results, Oil red O staining results showed that CAPE significantly suppressed MDI-induced adipogenesis of 3T3-L1 preadipocytes. FACS analysis results showed that CAPE delayed MDI-stimulated cell cycle progression, thereby contributing to inhibit mitotic clonal expansion (MCE), which is a prerequisite step for adipogenesis. Also, CAPE regulated the expression of cyclin D1 and the phosphorylation of ERK and Akt, which are upstream of cyclin D1. These results suggest that CAPE exerts an antiobesity effect in vivo, presumably through inhibiting adipogenesis at an early stage of adipogenesis.

A metabolite of daidzein, 6,7,4'-trihydroxyisoflavone, suppresses adipogenesis in 3T3-L1 preadipocytes via ATP-competitive inhibition of PI3K.

SCOPE: Daidzein is one of the major soy isoflavones. Following ingestion, daidzein is readily metabolized in the liver and converted into hydroxylated metabolites. One such metabolite is 6,7,4'-trihydroxyisoflavone (6,7,4'-THIF), which has been the focus of recent studies due to its various health benefits, however, its anti-adipogenic activity has not been investigated. Our objective was to determine the effects of 6,7,4'-THIF on adipogenesis in 3T3-L1 preadipocytes and elucidate the mechanisms of action involved. METHODS AND RESULTS: Adipogenesis was stimulated in 3T3-L1 preadipocytes. Both 6,7,4'-THIF and daidzein were treated in the presence and absence of mixture of isobutylmethylxanthine, dexamethasone, and insulin (MDI). We observed that 6,7,4'-THIF, but not daidzein, inhibited MDI-induced adipogenesis significantly at 40 and 80 µM, associated with decreased peroxisome proliferator-activated receptor-γ and C/EBP-α protein expression. 6,7,4'-THIF significantly suppressed MDI-induced lipid accumulation in the early stage of adipogenesis, attributable to a suppression of cell proliferation and the induction of cell cycle arrest. We also determined that 6,7,4'-THIF, but not daidzein, attenuated phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. 6,7,4'-THIF was found to inhibit PI3K activity via direct binding in an ATP-competitive manner. CONCLUSION: Our results suggest that 6,7,4'-THIF suppresses adipogenesis in 3T3-L1 preadipocytes by directly targeting PI3K. Soy isoflavones like 6,7,4'-THIF may have potential for development into novel treatment strategies for chronic obesity.

2'-Benzoyloxycinnamaldehyde inhibits nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 cells via regulation of AP-1 pathway.

Cinnamaldehyde, an active compound of cinnamon, has been reported to exert various biological functions such as anti-inflammatory and anti-tumor activities. Previously, we showed that 2'-hydroxycinnamaldehyde (HCA) has an inhibitory effect on nitric oxide (NO) production through the inhibition of NF-κB signaling. In an effort to find a more effective anti-atherosclerotic agent, here we evaluated the anti-inflammatory effect of 2'-benzoyloxycinnamaldehyde (BCA) in RAW 264.7 murine macrophage cells. We showed that BCA more effectively inhibited NO production than HCA with less cytotoxicity. We also demonstrated that BCA inhibited the lipopolysaccharide (LPS)-induced expression of iNOS in a concentration-dependent manner. Signal transduction studies showed that BCA significantly inhibited the phosphorylation of SAPK/JNK and AP-1-dependent reporter gene activity. LPS-induced expression levels of JunB, c-Jun and c-Fos were also decreased by BCA treatment. Moreover, the LPS-induced DNA binding activity of AP-1 was markedly inhibited by BCA. The direct injection of BCA into mice inhibited the LPS-induced increase in plasma nitrite levels, confirming the anti-inflammatory effect of BCA in vivo. Overall, these observations suggest that BCA has the potential for use as an anti-atherosclerotic agent.

An inhibitory effect of resveratrol in the mitotic clonal expansion and insulin signaling pathway in the early phase of adipogenesis.

Resveratrol is known as a potent antiobesity compound that acts partly through inhibition of adipogenesis. However, the direct targets responsible for its antiadipogenic action are unclear. Our hypothesis is that resveratrol inhibits adipogenesis through modulation of mitotic clonal expansion (MCE) and cell signaling pathways in the early phase of differentiation. To test this, we examined the effects of resveratrol on MCE and insulin signaling pathway in the early phase of adipogenesis in murine preadipocytes. We observed that the antiadipogenic action of resveratrol is largely limited to the early phase of adipogenesis. Specifically, the presence of resveratrol in the first 24 hours of adipogenesis was required for its antiadipogenic effect. During the first 24 hours of adipogenesis, resveratrol impaired the progression of MCE by suppressing the cell cycle entry of preadipocytes to G2/M phase, and expression of cell cycle regulators cyclin A and cyclin-dependent kinase 2. Concomitantly, resveratrol inhibited insulin signaling pathway in the early phase of adipogenesis. Furthermore, we revealed an inhibitory effect of resveratrol on insulin receptor (IR) activity, and this is likely through a direct physical interaction between resveratrol and IR. The antiadipogenic effect of resveratrol is through inhibition of the MCE and IR-dependent insulin signaling pathway in the early phase of adipogenesis.

Piceatannol, natural polyphenolic stilbene, inhibits adipogenesis via modulation of mitotic clonal expansion and insulin receptor-dependent insulin signaling in early phase of differentiation.

Piceatannol, a natural stilbene, is an analog and a metabolite of resveratrol. Despite a well documented health benefit of resveratrol in intervention of the development of obesity, the role of piceatannol in the development of adipose tissue and related diseases is unknown. Here, we sought to determine the function of piceatannol in adipogenesis and elucidate the underlying mechanism. We show that piceatannol inhibits adipogenesis of 3T3-L1 preadipocytes in a dose-dependent manner at noncytotoxic concentrations. This anti-adipogenic property of piceatannol was largely limited to the early event of adipogenesis. In the early phase of adipogenesis, piceatannol-treated preadipocytes displayed a delayed cell cycle entry into G(2)/M phase at 24 h after initiation of adipogenesis. Furthermore, the piceatannol-suppressed mitotic clonal expansion was accompanied by reduced activation of the insulin-signaling pathway. Piceatannol dose-dependently inhibited differentiation mixture-induced phosphorylation of insulin receptor (IR)/insulin receptor substrate-1 (IRS-1)/Akt pathway in the early phase of adipogenesis. Moreover, we showed that piceatannol is an inhibitor of IR kinase activity and phosphatidylinositol 3-kinase (PI3K). Our kinetics study of IR further identified a K(m) value for ATP of 57.8 µm and a K(i) value for piceatannol of 28.9 µm. We also showed that piceatannol directly binds to IR and inhibits IR kinase activity in a mixed noncompetitive manner to ATP, through which piceatannol appears to inhibit adipogenesis. Taken together, our study reveals an anti-adipogenic function of piceatannol and highlights IR and its downstream insulin signaling as novel targets for piceatannol in the early phase of adipogenesis.

Cyanidin-3-glucoside suppresses B[a]PDE-induced cyclooxygenase-2 expression by directly inhibiting Fyn kinase activity.

Benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE) is a well-known carcinogen that is associated with skin cancer. Abnormal expression of cyclooxygenase-2 (COX-2) is an important mediator in inflammation and tumor promotion. We investigated the inhibitory effect of cyanidin-3-glucoside (C3G), an anthocyanin present in fruits, on B[a]PDE-induced COX-2 expression in mouse epidermal JB6 P+ cells. Pretreatment with C3G resulted in the reduction of B[a]PDE-induced expression of COX-2 and COX-2 promoter activity. The activation of activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) induced by B[a]PDE was also attenuated by C3G. C3G attenuated the B[a]PDE-induced phosphorylation of MEK, MKK4, Akt, and mitogen-activated protein kinases (MAPKs), but no effect on the phosphorylation of the upstream MAPK regulator Fyn. However, kinase assays demonstrated that C3G suppressed Fyn kinase activity and C3G directly binds Fyn kinase noncompetitively with ATP. By using PP2, a pharmacological inhibitor for SFKs, we showed that Fyn kinase regulates B[a]PDE-induced COX-2 expression by activating MAPKs, AP-1 and NF-κB. These results suggest that C3G suppresses B[a]PDE-induced COX-2 expression mainly by blocking the activation of the Fyn signaling pathway, which may contribute to its chemopreventive potential.

Acrylamide up-regulates cyclooxygenase-2 expression through the MEK/ERK signaling pathway in mouse epidermal cells.

Acrylamide is formed during cooking processes and is present in many foods. Accumulating evidence suggests that AA is carcinogenic, but the underlying mechanism remains unclear. Here, we investigated the carcinogenesis mechanisms of AA. AA increased the COX-2 expression. Two major transcription factors, AP-1 and NF-κB, were activated by AA treatment. AA induced the ERK phosphorylation, and this was abolished by the treatment of U0126, a pharmacological inhibitor of MEK, an upstream kinase of ERK. AA-induced expression and promoter activity of COX-2 were suppressed by U0126. U0126 treatment attenuated AA-induced transactivation of AP-1 and NF-κB, suggesting that the MEK/ERK signaling pathway regulates COX-2 expression. In addition, myricetin, a natural inhibitor of the MEK/ERK signal pathway, reduced AA-induced activation of the COX-2 promoter as well as activation of AP-1 and NF-κB. Collectively, these results suggest that the ability of AA to up-regulate COX-2 expression through the MEK/ERK signaling pathway underlies AA carcinogenicity.

Cyanidin suppresses ultraviolet B-induced COX-2 expression in epidermal cells by targeting MKK4, MEK1, and Raf-1.

Skin cancer is the most frequently diagnosed cancer in the United States. Ultraviolet B (UVB) rays (wavelength: 280-320nm) play a pivotal role in the development of skin cancer by inducing the expression of inflammatory proteins such as cyclooxygenase-2 (COX-2). Cyanidin, the most plentiful of the plant pigments known as anthocyanidins, is a potent chemopreventive agent. In the present study, we examined the molecular mechanisms underlying the chemopreventive activity of cyanidin and identified its molecular targets. Cyanidin inhibited UVB-induced COX-2 expression and prostaglandin E(2) secretion in the epidermal skin cell line JB6 P+ by suppressing the transactivation of nuclear factor-kappaB and activator protein-1 which are well-known transcription factors regulated by mitogen-activated protein kinase. Cyanidin markedly inhibited the phosphorylation of JNK1/2, ERK1/2, and MEK1/2 than the of MKK4 and Raf-1, two upstream kinases of JNK1/2, ERK1/2, and MEK1/2. Cyanidin significantly suppressed the activities of MKK4, MEK1, and Raf-1 through direct binding. Transient transfection of a small interfering RNA specific for MKK4 inhibited the UVB-induced expression of COX-2 in JB6 P+ cells, as did the expression of a dominant-negative ERK2 mutant. We conclude that MKK4, MEK1, and Raf-1 are targets of cyanidin for the suppression of UVB-induced COX-2 expression.