A BODIPY-based fluorescent sensor for the detection of Pt2+ and Pt drugs.

A BODIPY-based fluorescent sensor PS with an NO4S2 podand ligand was studied for the selective detection of Pt2+ over 21 cations as well as selected platinum drugs in aqueous medium. The platinum sensor PS shows 28-fold, 22-fold and 14-fold fluorescence turn-on enhancements to Pt2+, cisplatin and nedaplatin, and was thereby employed to detect platinum drugs in A-549 human lung cancer cells.

Ribosome-Inactivating Protein α-Momorcharin Derived from Edible Plant Momordica charantia Induces Inflammatory Responses by Activating the NF-kappaB and JNK Pathways.

Alpha-momorcharin (α-MMC), a member of the ribosome-inactivating protein (RIP) family, has been found in the seeds of Momordica charantia (bitter melon). α-MMC contributes a number of pharmacological activities; however, its inflammatory properties have not been well studied. Here, we aim to determine the inflammatory responses induced by recombinant α-MMC and identify the underlying mechanisms using cell culture and animal models. Recombinant α-MMC was generated in Rosetta™(DE3)pLysS and purified by the way of nitrilotriacetic acid (NTA) chromatography. Treatment of recombinant α-MMC at 40 µg/mL exerted sub-lethal cytotoxic effect on THP-1 monocytic cells. Transcriptional profiling revealed that various genes coding for cytokines and other proinflammatory proteins were upregulated upon recombinant α-MMC treatment in THP-1 cells, including MCP-1, IL-8, IL-1ß, and TNF-α. Recombinant α-MMC was shown to activate IKK/NF-κB and JNK pathways and the α-MMC-induced inflammatory gene expression could be blocked by IKKß and JNK inhibitors. Furthermore, murine inflammatory models further demonstrated that α-MMC induced inflammatory responses in vivo. We conclude that α-MMC stimulates inflammatory responses in human monocytes by activating of IKK/NF-κB and JNK pathways, raising the possibility that consumption of α-MMC-containing food may lead to inflammatory-related diseases.

Synthesis and study of Au(iii)-indolizine derivatives: turn-on luminescence by photo-induced controlled release.

The photo- and structural properties of a series of Au(iii) indolizine complexes were determined. Controlled release of halogenated indolizine derivatives from the corresponding Au(iii) complexes was achieved by photoinduced C-X bond formation, which provided turn-on luminescence with an increase in emission intensity of up to 67 times.

An ethanolic extract of the aerial part of Siegesbeckia orientalis L. inhibits the production of inflammatory mediators regulated by AP-1, NF-κB and IRF3 in LPS-stimulated RAW 264.7 cells.

Herba Siegesbeckiae (HS, the dried aerial part of Siegesbeckia orientalis L.) is a commonly used traditional Chinese medicinal herb for treating inflammatory diseases. HS has been reported to exert anti-inflammatory effects by inhibiting the MAPKs and NF-κB pathways, the downstream effectors of TLR4 signalling. This study aims to further investigate the involvement of TLR4 signalling cascades in the effects of an ethanolic extract of HS (HS for short) on inflammatory mediators in murine macrophages. HS was extracted using 50% ethanol. Lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages were used as the cell model. ELISA was used to detect cytokine/chemokine secretion. Real time-PCR and immunoblotting were used to examine mRNA and protein levels, respectively. We observed that HS dose-dependently inhibited the secretion of PGE2, MCP-1, MIP-1α and RANTES, and down-regulated mRNA levels of iNOS, COX-2, IL-1ß, IL-6, TNF-α, mPGES-1, MCP-1, MIP-1α and RANTES in LPS-stimulated RAW264.7 cells. HS did not affect the protein levels of TAK1, TBK1, PI3K, Akt, IKK, c-Jun, c-Fos and IRF3, while, dose-dependently decreased levels of their phosphorylated forms. The protein levels of IRAK1 and IRAK4 were upregulated, while those of TRAF6 and TRAF3 were downregulated by HS. Moreover, the nuclear protein levels of AP-1, NF-κB and IRF3 were dose-dependently decreased by HS. These results indicate that suppression of the IRAK4/MAPKs/AP-1, IRAK4/MAPKs/NF-κB, IRAK4/PI3K/NF-κB and TRAF3/TBK1/IRF3 pathways is associated with the inhibitory effects of HS on inflammatory mediators in LPS-stimulated RAW264.7 cells. This study provides a pharmacological basis for the clinical application of this herb in the treatment of inflammatory disorders.

Comparison of the chemical profiles and inflammatory mediator-inhibitory effects of three Siegesbeckia herbs used as Herba Siegesbeckiae (Xixiancao).

BACKGROUND: Herba Siegesbeckiae (HS, Xixiancao in Chinese) is a commonly used traditional Chinese medicinal herb for soothing joints. In ancient materia medica books, HS is recorded to be the aerial part of Siegesbeckia pubescens Makino (SP) which is also the only origin of HS in the 1963 edition of the Chinese Pharmacopeia (ChP). The aerial parts of Siegesbeckia orientalis L. (SO) and Siegesbeckia glabrescens Makino (SG) have been included as two additional origins for HS in each edition of ChP since 1977. However, chemical and pharmacological comparisons among these three species have not been conducted. METHODS: An HPLC with diode array detector (HPLC-DAD) method combined with similarity analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA) was developed for comparing the fingerprint chromatograms of the three species. The inhibitory effects of the three species on NO production and IL-6 secretion in LPS-stimulated RAW264.7 macrophages were compared. RESULTS: Fingerprint chromatograms of the three species showed different profiles, but had 13 common peaks. Results from HCA and PCA of the common peaks demonstrated that all 14 herbal samples of the three species tended to be grouped and separated species dependently. The extents of inhibition on NO production and IL-6 secretion of the three species were different, with SG being the most and SP the least potent. CONCLUSIONS: Both chemical profiles and inflammatory mediator-inhibitory effects of the three species were different. These findings provide a chemical and pharmacological basis for determining whether the three species can all serve as the origins of HS.

Antrodia camphorata Mycelia Exert Anti-liver Cancer Effects and Inhibit STAT3 Signaling in vitro and in vivo.

Hepatocellular carcinoma (HCC), the major form of primary liver cancer, is a common cause of cancer-related death worldwide. Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in HCC and has been proposed as a chemotherapeutic target for HCC. Antrodia camphorata (AC), a medicinal mushroom unique to Taiwan, is traditionally used for treating HCC. Whereas natural AC is scarce, cultured AC mycelia are becoming alternatives. In this study, we investigated the anti-HCC effects of the ethyl acetate fraction of an ethanolic extract of AC mycelia (EEAC), particularly exploring the involvement of STAT3 signaling in these effects. We found that EEAC reduced cell viability, induced apoptosis, and retarded migration and invasion in cultured HepG2 and SMMC-7721 cells. Immunoblotting results showed that EEAC downregulated protein levels of phosphorylated and total STAT3 and JAK2 (an upstream kinase of STAT3) in HCC cells. Real-time PCR analyses showed that STAT3, but not JAK2, mRNA levels were decreased by EEAC. EEAC also lowered the protein level of nuclear STAT3, decreased the transcriptional activity of STAT3, and downregulated protein levels of STAT3-targeted molecules, including anti-apoptotic proteins Bcl-xL and Bcl-2, and invasion-related proteins MMP-2 and MMP-9. Over-activation of STAT3 in HCC cells diminished the cytotoxic effects of EEAC. In SMMC-7721 cell-bearing mice, EEAC (100 mg/kg, i.g. for 18 days) significantly inhibited tumor growth. Consistent with our in vitro data, EEAC induced apoptosis and suppressed JAK2/STAT3 activation/phosphorylation in the tumors. Taken together, EEAC exerts anti-HCC effects both in vitro and in vivo; and inhibition of STAT3 signaling is, at least in part, responsible for these effects. We did not observe significant toxicity of EEAC in normal human liver-derived cells, nude mice and rats. Our results provide a pharmacological basis for developing EEAC as a safe and effective agent for HCC management.

Computational and experimental prediction of molecules involved in the anti-melanoma action of berberine.

ETHNOPHARMACOLOGIC RELEVANCE: Berberine (BBR) is a naturally occurring alkaloid compound that can be found in Chinese medicinal herbs such as Rhizoma Coptidis and Phellodendri Cortex. These BBR containing herbs are commonly used by Chinese medicine doctors to treat cancers including melanoma. In this study, we explored proteins potentially involved in the anti-melanoma effects of BBR using computational and experimental approaches. MATERIALS AND METHODS: Target proteins of BBR were predicted using the reverse pharmacophore screening, molecular docking and molecular dynamics. Anti-melanoma activities of BBR in melanoma cells were examined by MTT and EdU proliferation assays. Effects of BBR on activities of target proteins in melanoma cells were examined by Western blotting or fluorescence assay. RESULTS: Ten proteins implicated in cancer and with high fit-score in the reverse pharmacophore screening were selected as potential targets of BBR. Molecular docking and molecular dynamics revealed that BBR could stably bind to four of the ten proteins, namely 3-phosphoinositide-dependent protein kinase 1 (PDK1), glucocorticoid receptor (GR), p38 mitogen-activated protein kinase (p38) and dihydroorotate dehydrogenase (DHODH). Cellular experiments showed that BBR inhibited cell proliferation, increased the phosphorylation of GR and p38, and inhibited the activity of DHODH in A375 human melanoma cells. CONCLUSIONS: These findings suggest that p38, GR and DHODH are potentially involved in the anti-melanoma action of BBR. This study provided a chemical and pharmacological justification for the clinical use of BBR-containing herbs in melanoma treatment.

Inhibiting STAT3 signaling is involved in the anti-melanoma effects of a herbal formula comprising Sophorae Flos and Lonicerae Japonicae Flos.

A herbal formula (SL) comprising Sophorae Flos and Lonicerae Japonicae Flos was traditionally used to treat melanoma. Constitutively active signal transducer and activator of transcription 3 (STAT3) has been proposed as a therapeutic target in melanoma. Here we investigated whether an ethanolic extract of SL (SLE) exerted anti-melanoma activities by inhibiting STAT3 signaling. B16F10 allograft model, A375 and B16F10 cells were employed to assess the in vivo and in vitro anti-melanoma activities of SLE. A375 cells stably expressing STAT3C, a constitutively active STAT3 mutant, were used to determine the role of STAT3 signaling in SLE's anti-melanoma effects. Intragastric administration of SLE (1.2 g/kg) potently inhibited melanoma growth in mice and inhibited STAT3 phosphorylation in the tumors. In cultured cells, SLE dramatically reduced cell viability, induced apoptosis, suppressed migration and invasion, and restrained STAT3 activation and nuclear localization. STAT3C overexpression in A375 cells diminished SLE's effects on cell viability, apoptosis and invasion. Collectively, SLE exerted potent anti-melanoma effects partially by inhibiting STAT3 signaling. This study provides pharmacological justification for the traditional use of this formula in treating melanoma, and suggests that SLE has the potential to be developed as a modern alternative and/or complimentary agent for melanoma treatment and prevention.

Sensitization of melanoma cells to alkylating agent-induced DNA damage and cell death via orchestrating oxidative stress and IKKß inhibition.

Nitrosourea represents one of the most active classes of chemotherapeutic alkylating agents for metastatic melanoma. Treatment with nitrosoureas caused severe systemic side effects which hamper its clinical use. Here, we provide pharmacological evidence that reactive oxygen species (ROS) induction and IKKß inhibition cooperatively enhance nitrosourea-induced cytotoxicity in melanoma cells. We identified SC-514 as a ROS-inducing IKKß inhibitor which enhanced the function of nitrosoureas. Elevated ROS level results in increased DNA crosslink efficiency triggered by nitrosoureas and IKKß inhibition enhances DNA damage signals and sensitizes nitrosourea-induced cell death. Using xenograft mouse model, we confirm that ROS-inducing IKKß inhibitor cooperates with nitrosourea to reduce tumor size and malignancy in vivo. Taken together, our results illustrate a new direction in nitrosourea treatment, and reveal that the combination of ROS-inducing IKKß inhibitors with nitrosoureas can be potentially exploited for melanoma therapy.

Icariside II overcomes TRAIL resistance of melanoma cells through ROS-mediated downregulation of STAT3/cFLIP signaling.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising antitumor agent. However, many melanoma cells show weak responses to TRAIL. Here, we investigated whether Icariside II (IS), an active component of Herba Epimedii, could potentiate antitumor effects of TRAIL in melanoma cells. Melanoma cells were treated with IS and/or TRAIL and cell death, apoptosis and signal transduction were analyzed. We showed that IS promoted TRAIL-induced cell death and apoptosis in A375 melanoma cells. Mechanistically, IS reduced the expression levels of cFLIP in a phospho-STAT3 (pSTAT3)-dependent manner. Ectopic expression of STAT3 abolished IS-induced cFLIP down-regulation and the associated potentiation of TRAIL-mediated cell death. Moreover, IS-induced reactive oxygen species (ROS) production preceded down-regulation of pSTAT3/cFLIP via activating AKT, and the consequent sensitization of cells to TRAIL. We also found that IS treatment down-regulated cFLIP via ROS-mediated NF-κB pathway. In addition, IS converted TRAIL-resistant melanoma MeWo and SK-MEL-28 cells into TRAIL-sensitive cells. Taken together, our results indicated that IS potentiated TRAIL-induced apoptosis through ROS-mediated down-regulation of STAT3/cFLIP signaling.

Iciartin, a novel FASN inhibitor, exerts anti-melanoma activities through IGF-1R/STAT3 signaling.

Icaritin (IT) is a flavonoid isolated from Herba Epimedii. In this study, we evaluated the anti-melanoma activities of IT, and determined its cytotoxic mechanism. We found that IT exerted cytotoxicity to melanoma cells. Furthermore, IT induced melanoma cell apoptosis, which was accompanied with PARP cleavage. Mechanistically, IT suppressed p-STAT3 (tyr705) level in parallel with increases of p-STAT3 (ser727), p-ERK and p-AKT. IT significantly inhibited STAT3 nuclear translocation and reduced the levels of STAT3 -targeted genes. IT also inhibited IGF-1-induced STAT3 activation through down-regulation of total IGF-1R level. No dramatic changes in IGF-1R mRNA levels were observed in IT-treated cells, suggesting that IT acted primarily at a post-transcriptional level. Using molecular docking analysis, IT was identified as a novel fatty acid synthase (FASN) inhibitor. We found that IT reduced the level of total IGF-1R via FASN inhibition. In summary, we reported that IT exerted anti-melanoma activities, and these effects were partially due to inhibition of FASN/IGF-1R/STAT3 signaling.

Inhibition of the STAT3 signaling pathway contributes to apigenin-mediated anti-metastatic effect in melanoma.

Signal transducer and activator of transcription 3 (STAT3) signaling is constantly activated in human melanoma, and promotes melanoma metastasis. The dietary flavonoid apigenin is a bioactive compound that possesses low toxicity and exerts anti-metastatic activity in melanoma. However, the anti-metastasis mechanism of apigenin has not been fully elucidated. In the present study, we showed that apigenin suppressed murine melanoma B16F10 cell lung metastasis in mice, and inhibited cell migration and invasion in human and murine melanoma cells. Further study indicated that apigenin effectively suppressed STAT3 phosphorylation, decreased STAT3 nuclear localization and inhibited STAT3 transcriptional activity. Apigenin also down-regulated STAT3 target genes MMP-2, MMP-9, VEGF and Twist1, which are involved in cell migration and invasion. More importantly, overexpression of STAT3 or Twist1 partially reversed apigenin-impaired cell migration and invasion. Our data not only reveal a novel anti-metastasis mechanism of apigenin but also support the notion that STAT3 is an attractive and promising target for melanoma treatment.

A herbal formula comprising Rosae Multiflorae Fructus and Lonicerae Japonicae Flos, attenuates collagen-induced arthritis and inhibits TLR4 signalling in rats.

RL, a traditional remedy for Rheumatoid arthritis (RA), comprises two edible herbs, Rosae Multiflorae Fructus and Lonicerae Japonicae Flos. We have reported that RL could inhibit the production of inflammatory mediators in immune cells. Here we investigated the effects and the mechanism of action of RL in collagen-induced arthritis (CIA) rats. RL significantly increased food intake and weight gain of CIA rats without any observable adverse effect; ameliorated joint erythema and swelling; inhibited immune cell infiltration, bone erosion and osteophyte formation in joints; reduced joint protein expression levels of TLR4, phospho-TAK1, phospho-NF-κB p65, phospho-c-Jun and phospho-IRF3; lowered levels of inflammatory factors (TNF-α, IL-6, IL-1ß, IL-17A and MCP-1 in sera and TNF-α, IL-6, IL-1ß and IL-17A in joints); elevated serum IL-10 level; reinvigorated activities of antioxidant SOD, CAT and GSH-Px in the liver and serum; reduced Th17 cell proportions in splenocytes; inhibited splenocyte proliferation and activation; and lowered serum IgG level. In conclusion, RL at nontoxic doses inhibited TLR4 signaling and potently improved clinical conditions of CIA rats. These findings provide further pharmacological justifications for the traditional use of RL in RA management.

Comparison of the toxicities, activities and chemical profiles of raw and processed Xanthii Fructus.

BACKGROUND: Although toxic, the Chinese medicinal herb Xanthii Fructus (XF) is commonly used to treat traditional Chinese medicine (TCM) symptoms that resemble cold, sinusitis and arthritis. According to TCM theory, stir-baking (a processing method) can reduce the toxicity and enhance the efficacy of XF. METHODS: Cytotoxicities of raw XF and processed XF (stir-baked XF, SBXF) were determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in normal liver derived MIHA cells. Nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA expression were measured by the Griess reagent and quantitative real-time PCR, respectively. The chemical profiles of XF and SBXF were compared using an established ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS) method. RESULTS: SBXF was less toxic than XF in MIHA cells. Both XF and SBXF had anti-inflammatory effects as demonstrated by their abilities to reduce nitric oxide production as well as inducible nitric oxide synthase mRNA expression in lipopolysaccharide-stimulated RAW 264.7 macrophages. Interestingly, the anti-inflammatory effects of SBXF were more potent than that of XF. By comparing the chemical profiles, we found that seven peaks were lower, while nine other peaks were higher in SBXF than in XF. Eleven compounds including carboxyatractyloside, atractyloside and chlorogenic acid corresponding to eleven individual changed peaks were tentatively identified by matching with empirical molecular formulae and mass fragments, as well as literature data. CONCLUSION: Our study showed that stir-baking significantly reduced the cytotoxicity and enhanced the anti-inflammatory effects of XF; moreover, with a developed ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry method we differentiated XF and SBXF by their chemical profiles. Further studies are warranted to establish the relationship between the alteration of chemical profiles and the changes of medicinal properties caused by stir-baking.

Centipeda minima (Ebushicao) extract inhibits PI3K-Akt-mTOR signaling in nasopharyngeal carcinoma CNE-1 cells.

BACKGROUND: Centipeda minima (Ebushicao) has been used for the treatment of various diseases, such as nasal allergies, rhinitis and sinusitis, nasopharyngeal carcinoma, cough, and headache. This study aims to investigate the anticancer activities of Centipeda minima ethanol extracts (CME) against nasopharyngeal carcinoma cell CNE-1 and their underlying mechanism. METHODS: CNE-1 cells were treated with different concentrations (15-50 µg/mL) of CME for different time intervals (24, 48, and 72 h). Cytotoxicity of CME was determined by MTT assay. Cell morphological changes were observed by fluorescence microscopy after HO 33258 staining. Cell cycle status was evaluated by flow cytometry following propidium iodide staining. Apoptosis was detected by flow cytometry following annexin V-FITC/PI staining. The levels of apoptosis-associated and PI3K-Akt-mTOR signaling related proteins were measured by western blotting analysis. RESULTS: CME (15-50 µg/mL) significantly inhibited the proliferation of CNE-1 in a dose- and time-dependent manner (P = 0.026 for 15 µg/mL, P < 0.001 for 25, 30, 40, and 50 µg/mL, respectively); the IC50 values (µg/mL) were 41.57 ± 0.17, 30.34 ± 0.06 and 24.98 ± 0.08 for 24, 48 and 72 h treatments, respectively. Significant morphological changes of CNE-1 cells displaying apoptosis were observed after CME treatment. CME showed low cytotoxicity toward normal LO2 cells. CNE-1 cells were arrested in the G2/M phase while treated with 15, 25, 40 µg/mL of CME, respectively (P = 0.032, P = 0.0053, P < 0.001). CME (15, 25, 40 µg/mL) down-regulated Bcl-2 expression (P = 0.032, P = 0.0074, P < 0.001), and up-regulated Bax (P = 0.026, P = 0.0056, P < 0.001) with activation of caspase-3, caspase-8, caspase-9, and PARP observed in CNE-1 cells (P = 0.015, P = 0.0067, P < 0.001 for caspase 3; P = 0.210, 0.028, < 0.001 for caspase 8; P = 0.152, 0.082, 0.0080 for caspase 9; P = 0.265, 0.0072, < 0.001 for PARP). CME suppressed the activation of the PI3K-AKT-mTOR pathway (P = 0.03, 0.0007, 0.004, 0.006, 0.022 for p-PI3K, p-Akt-Ser(473), p-Akt-Thr(308), p-mTOR-Ser(2448), p-mTOR-Ser(2481), respectively after 40 µg/mL of CME treated for 24 h). CONCLUSION: CME inhibited the proliferation of CNE-1 cells and activation of the PI3K-AKT-mTOR signaling pathway.

A herbal formula comprising Rosae Multiflorae Fructus and Lonicerae Japonicae Flos inhibits the production of inflammatory mediators and the IRAK-1/TAK1 and TBK1/IRF3 pathways in RAW 264.7 and THP-1 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: As documented in the Chinese Materia Medica Grand Dictionary (), a herbal formula (RL) consisting of Rosae Multiflorae Fructus (multiflora rose hips) and Lonicerae Japonicae Flos (Japanese honeysuckle flowers) has traditionally been used in treating inflammatory disorders. RL was previously reported to inhibit the expression of various inflammatory mediators regulated by NF-κB and MAPKs that are components of the TLR4 signalling pathways. AIM OF THE STUDY: This study aims to provide further justification for clinical application of RL in treating inflammatory disorders by further delineating the involvement of the TLR4 signalling cascades in the effects of RL on inflammatory mediators. MATERIALS AND METHODS: RL consisting of Rosae Multiflorae Fructus and Lonicerae Japonicae Flos (in 5:3 ratio) was extracted using absolute ethanol. We investigated the effect of RL on the production of cytokines and chemokines that are regulated by three key transcription factors of the TLR4 signalling pathways AP-1, NF-κB and IRF3 in LPS-stimulated RAW264.7 cells using the multiplex biometric immunoassay. Phosphorylation of AP-1, NF-κB, IRF3, IκB-α, IKKα/ß, Akt, TAK1, TBK1, IRAK-1 and IRAK-4 were examined in LPS-stimulated RAW264.7 cells and THP-1 cells using Western blotting. Nuclear localizations of AP-1, NF-κB and IRF3 were also examined using Western blotting. RESULTS: RL reduced the secretion of various pro-inflammatory cytokines and chemokines regulated by transcription factors AP-1, NF-κB and IRF3. Phosphorylation and nuclear protein levels of these transcription factors were decreased by RL treatment. Moreover, RL inhibited the activation/phosphorylation of IκB-α, IKKα/ß, TAK1, TBK1 and IRAK-1. CONCLUSIONS: Suppression of the IRAK-1/TAK1 and TBK1/IRF3 signalling pathways was associated with the effect of RL on inflammatory mediators in LPS-stimulated RAW264.7 and THP-1 cells. This provides further pharmacological basis for the clinical application of RL in the treatment of inflammatory disorders.

ERK/GSK3ß signaling is involved in atractylenolide I-induced apoptosis and cell cycle arrest in melanoma cells.

Novel agents need to be developed to overcome the limitations of the current melanoma therapeutics. Atractylenolide I (AT-I) is a sesquiterpene compound isolated from atractylodis macrocephalae rhizoma. Previous findings demonstrated that AT-I exhibited cytotoxic action in melanoma cells. However, the molecular mechanisms of AT­1's anti-melanoma properties remain to be elucidated. In the present study, the cell cycle-arrest and apoptosis-promoting effects as well as the ERK/GSK3ß signaling-related mechanism of action of AT-I were examined. B16 melanoma cells were treated with various concentrations of AT-1 (50, 75 and 100 µM) for 48 or 72 h. Cell cycle and apoptosis were analyzed by flow cytometry. Protein expression levels were detected by western blot analysis. AT-I treatment induced G1 phase arrest, which was accompanied by increased p21 and decreased CDK2 protein expression levels. Apoptosis was observed after AT-I treatment for 72 h, which was accompanied by activated caspase­3 and ­8. AT-I treatment significantly decreased phospho-ERK, phospho-GSK3ß, c-Jun and increased p53 protein expression levels. Lithium chloride (LiCl, 5 mM), a GSK3ß inhibitor, treatment alone did not increase the apoptosis of B16 cells, while pretreatment with LiCl markedly reversed AT-I-induced apoptosis. Additionally, AT-I-induced G1 phase arrest was partially reversed by LiCl pretreatment. In conclusion, ERK/GSK3ß signaling was involved in the apoptotic and G1 phase arrest effects of AT-I in melanoma cells.

Quercetin inhibits HGF/c-Met signaling and HGF-stimulated melanoma cell migration and invasion.

BACKGROUND: Melanoma is notorious for its propensity to metastasize, which makes treatment extremely difficult. Receptor tyrosine kinase c-Met is activated in human melanoma and is involved in melanoma progression and metastasis. Hepatocyte growth factor (HGF)-mediated activation of c-Met signaling has been suggested as a therapeutic target for melanoma metastasis. Quercetin is a dietary flavonoid that exerts anti-metastatic effect in various types of cancer including melanoma. In a previous report, we demonstrated that quercetin inhibited melanoma cell migration and invasion in vitro, and prevented melanoma cell lung metastasis in vivo. In this study, we sought to determine the involvement of HGF/c-Met signaling in the anti-metastatic action of quercetin in melanoma. METHODS: Transwell chamber assay was conducted to determine the cell migratory and invasive abilities. Western blotting was performed to determine the expression levels and activities of c-Met and its downstream molecules. And immunoblotting was performed in BS(3) cross-linked cells to examine the homo-dimerization of c-Met. Quantitative real-time PCR analysis was carried out to evaluate the mRNA expression level of HGF. Transient transfection was used to overexpress PAK or FAK in cell models. Student's t-test was used in analyzing differences between two groups. RESULTS: Quercetin dose-dependently suppressed HGF-stimulated melanoma cell migration and invasion. Further study indicated that quercetin inhibited c-Met phosphorylation, reduced c-Met homo-dimerization and decreased c-Met protein expression. The effect of quercetin on c-Met expression was associated with a reduced expression of fatty acid synthase. In addition, quercetin suppressed the phosphorylation of c-Met downstream molecules including Gab1 (GRB2-associated-binding protein 1), FAK (Focal Adhesion Kinase) and PAK (p21-activated kinases). More importantly, overexpression of FAK or PAK significantly reduced the inhibitory effect of quercetin on the migration of the melanoma cells. CONCLUSIONS: Our findings suggest that suppression of the HGF/c-Met signaling pathway contributes to the anti-metastatic action of quercetin in melanoma.

Inhibition of STAT3 signalling contributes to the antimelanoma action of atractylenolide II.

Our previous studies showed that atractylenolide II (AT-II) has antimelanoma effects in B16 melanoma cells. In this study, we investigated the involvement of STAT3 signalling in the antimelanoma action of AT-II. Daily administration of AT-II (12.5, 25 mg/kg, i.g.) for 14 days significantly inhibited tumor growth in a B16 xenograft mouse model and inhibited the activation/phosphorylation of STAT3 and Src in the xenografts. In B16 and A375 cells, AT-II (20, 40 µm) treatment for 48 h dose-dependently reduced protein expression levels of phospho-STAT3, phospho-Src, as well as STAT3-regulated Mcl-1 and Bcl-xL. Overexpression of a constitutively active variant of STAT3, STAT3C in A375 cells diminished the antiproliferative and apoptotic effects of AT-II. These data suggest that inhibition of STAT3 signalling contributes to the antimelanoma action of AT-II. Our findings shed new light on the mechanism of action underlying the antimelanoma effects of AT-II and provide further pharmacological basis for developing AT-II as a novel melanoma chemopreventive/chemotherapeutic agent.

Quercetin exerts anti-melanoma activities and inhibits STAT3 signaling.

Melanoma is highly resistant to chemotherapy, and the mortality rate is increasing rapidly worldwide. STAT3 signaling has been implicated in the pathogenesis of melanoma and constitutive activated STAT3 has been validated can as a target for melanoma therapy. Quercetin, a noncarcinogenic dietary flavonoid with low toxicity, has been shown to exert anti-melanoma activity. However, the anti-melanoma mechanisms of quercetin are not fully understood. In this study, we sought to test the involvement of STAT3 signaling in the inhibitory effects of quercetin on melanoma cell growth, migration and invasion. Our results showed that exposure to quercetin resulted in inhibition of proliferation of melanoma cells, induction of cell apoptosis, and suppression of migratory and invasive properties. Mechanistic study indicated that quercetin inhibited the activation of STAT3 signaling by interfering with STAT3 phosphorylation, and reducing STAT3 nuclear localization. This inhibited STAT3 transcription activity and down-regulated STAT3 targeted genes Mcl-1, MMP-2, MMP-9 and VEGF, which are involved in cell growth, migration and invasion. Importantly, overexpression of constitutively active STAT3 partially rescued the growth inhibiting effects induced by quercetin. Furthermore, quercetin suppressed A375 tumor growth and STAT3 activities in xenografted mice model, and inhibited murine B16F10 cells lung metastasis in an animal model. Overall, these results indicate that the antitumor activity of quercetin is at least partially due to inhibition of STAT3 signaling in melanoma cells. Our findings provided new insight into the action of quercetin potently inhibits the STAT3 signaling pathway, suggesting it has a potential role in the prevention and treatment of melanoma.