A Dimerosesquiterpene and Sesquiterpene Lactones from Artemisia argyi Inhibiting Oncogenic PI3K/AKT Signaling in Melanoma Cells.

A library of more than 2500 plant extracts was screened for activity on oncogenic signaling in melanoma cells. The ethyl acetate extract from the aerial parts of Artemisia argyi displayed pronounced inhibition of the PI3K/AKT pathway. Active compounds were tracked with the aid of HPLC-based activity profiling, and altogether 21 active compounds were isolated, including one novel dimerosequiterpenoid (1), one new disesquiterpenoid (2), three new guaianolides (3-5), 12 known sesquiterpenoids (6-17), and four known flavonoids (19-22). A new eudesmanolide derivative (13b) was isolated as an artifact formed by methanolysis. Compound 1 is the first adduct comprising a sesquiterpene lactone and a methyl jasmonate moiety. The absolute configurations of compounds 1 and 3-18 were established by comparison of their experimental and calculated ECD spectra. The absolute configuration for 2 was determined by X-ray diffraction analysis. Guaianolide 8 was the most potent sesquiterpene lactone, inhibiting the PI3K/AKT pathway with an IC50 value of 8.9 ± 0.9 µM.

Cajanin Suppresses Melanin Synthesis through Modulating MITF in Human Melanin-Producing Cells.

Despite its classification as a non-life-threatening disease, increased skin pigmentation adversely affects quality of life and leads to loss of self-confidence. Until now, there are no recommended remedies with high efficacy and human safety for hyperpigmentation. This study aimed to investigate anti-melanogenic activity and underlying mechanism of cajanin, an isoflavonoid extracted from Dalbergia parviflora Roxb. (Leguminosae) in human melanin-producing cells. Culture with 50 µM cajanin for 48-72 h significantly suppressed proliferation in human melanoma MNT1 cells assessed via MTT viability assay. Interestingly, cajanin also efficiently diminished melanin content in MNT1 cells with the half maximum inhibitory concentration (IC50) at 77.47 ± 9.28 µM. Instead of direct inactivating enzymatic function of human tyrosinase, down-regulated mRNA and protein expression levels of MITF and downstream melanogenic enzymes, including tyrosinase, TRP-1 and Dct (TRP-2) were observed in MNT1 cells treated with 50 µM cajanin for 24-72 h. Correspondingly, treatment with cajanin modulated the signaling pathway of CREB and ERK which both regulate MITF expression level. Targeted suppression on MITF-related proteins in human melanin-producing cells strengthens the potential development of cajanin as an effective treatment for human hyperpigmented disorders.

Berberine-photodynamic therapy sensitizes melanoma cells to cisplatin-induced apoptosis through ROS-mediated P38 MAPK pathways.

The clinical use of cisplatin are limited due to its drug resistance. Thus, it is urgent to find effective combination therapy that sensitizes tumor cells to this drug. The combined chemo-photodynamic therapy could increase anti-tumor efficacy while also reduce the side effects of cisplatin. Berberine is an isoquinoline alkaloid, which has been reported to show high photosensitizing activity. In this study, we have examined the effect of a combination of cisplatin and berberine-PDT in cisplatin-resistant melanoma cells. The cytotoxic effects of berberine-PDT alone or in combination with cisplatin were tested by MTT assays. We then examined the subcellular localization of berberine with confocal fluorescence microscopy. The percentage of apoptotic cells, the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) generation assessed using flow cytometry analysis. Western blotting used in this study to determine the expression levels of MAPK signaling pathways and apoptosis-related proteins. Experimental data revealed that the mode of cell death is the caspase-dependent mitochondrial apoptotic pathways. Excessive accumulation of ROS played a key role in this process, which is confirmed by alleviation of cytotoxicity upon pretreatment with NAC. Furthermore, we found that the combined treatment activated MAPK signaling pathway. The inhibition of p38 MAPK by pretreating with SB203580 block the combined treatment-induced apoptotic cell death. In conclusion, berberine-PDT could be used as a chemo-sensitizer by promoting cell death through activation of a ROS/p38/caspase cascade.

22ß-hydroxytingenone induces apoptosis and suppresses invasiveness of melanoma cells by inhibiting MMP-9 activity and MAPK signaling.

ETHNOPHARMACOLOGICAL RELEVANCE: 22ß-hydroxytingenone (22-HTG) is a quinonemethide triterpene isolated from Salacia impressifolia (Miers) A. C. Smith (family Celastraceae), which has been used in traditional medicine to treat a variety of diseases, including dengue, renal infections, rheumatism and cancer. However, the anticancer effects of 22-HTG and the underlying molecular mechanisms in melanoma cells have not yet been elucidated. AIM OF THE STUDY: The present study investigated apoptosis induction and antimetastatic potencial of 22-HTG in SK-MEL-28 human melanoma cells. MATERIALS AND METHODS: First, the in vitro cytotoxic activity of 22-HTG in cultured cancer cells was evaluated. Then, cell viability was determined using the trypan blue assay in melanoma cells (SK-MEL-28), which was followed by cell cycle, annexin V-FITC/propidium iodide assays (Annexin/PI), as well as assays to evaluate mitochondrial membrane potential, production of reactive oxygen species (ROS) using flow cytometry. Fluorescence microscopy using acridine orange/ethidium bromide (AO/BE) staining was also performed. RT-qPCR was carried out to evaluate the expression of BRAF, NRAS, and KRAS genes. The anti-invasiveness potential of 22-HTG was evaluated in a three-dimensional (3D) model of reconstructed human skin. RESULTS: 22-HTG reduced viability of SK-MEL-28 cells and caused morphological changes, as cell shrinkage, chromatin condensation, and nuclear fragmentation. Furthermore, 22-HTG caused apoptosis, which was demonstrated by increased staining with AO/BE and Annexin/PI. The apoptosis may have been caused by mitochondrial instability without the involvement of ROS production. The expression of BRAF, NRAS, and KRAS, which are important biomarkers in melanoma development, was reduced by the 22-HTG treatment. In the reconstructed skin model, 22-HTG was able to decrease the invasion capacity of melanoma cells in the dermis. CONCLUSIONS: Our data indicate that 22-HTG has anti-tumorigenic properties against melanoma cells through the induction of cell cycle arrest, apoptosis and inhibition of invasiveness potential, as observed in the 3D model. As such, the results provide new insights for future work on the utilization of 22-HTG in malignant melanoma treatment.

[Millimeter wave exposure induces apoptosis in human melanoma A375 cells in vitro].

OBJECTIVE: To investigate the effects of millimeter wave (MMW) exposure on apoptosis of human melanoma A375 cells and explore the mechanisms. METHODS: Through electromagnetic field calculation we simulated MMW exposure in cells and calculated the specific absorption rate (SAR). The optimal irradiation parameters were determined according to the uniformity and intensity of the SAR. A375 cells were then exposed to MMV for 15, 30, 60, or 90 min, with or without pretreatment with the caspase-3 inhibitor AC-DEVD-fmk (10 µmol/L) for 1 h at 90 min before the exposure. CCK-8 assay was used to assess the changes in the viability and Annexin-V/ PI staining was used to detect the apoptosis of the cells following the exposures; Western blotting was used to detect the expression of caspase-3 in the cells. RESULTS: The results of electromagnetic field calculation showed that for optimal MMV exposure, the incident field needed to be perpendicular to the bottom of the plastic Petri dish with the antenna placed below the dish. CCk-8 assay showed that MMW exposure significantly inhibited the cell viability in a time-dependent manner (P < 0.05); exposures for 15, 30, 60, and 90 min all resulted in significantly increased apoptosis of the cells (P < 0.05). The cells with MMW exposure showed significantly increased expression of caspase-3. The inhibitory effect of MMW on the cell viability was antagonized significantly by pretreatment of the cells with AC-DEVD-fmk (P < 0.05), which increased the cell viability rate from (36.7±0.09)% to (59.8±0.06)% (P < 0.05). CONCLUSIONS: 35.2 GHz millimeter wave irradiation induces apoptosis in A375 cells by activating the caspase-3 protein.

Anti-Oxidant and Anti-Melanogenic Properties of Essential Oil from Peel of Pomelo cv. Guan Xi.

Here, we investigated the anti-oxidant and anti-melanogenic effects of pomelo peel essential oil (PPEO) from pomelo cv. Guan Xi. The volatile chemical composition of PPEO was analyzed with gas chromatography⁻mass spectrometry (GC/MS). The most abundant component of PPEO was limonene (55.92%), followed by ß-myrcene (31.17%), and ß-pinene (3.16%). PPEO showed strong anti-oxidant activities against 1,1-diphenyl-2-picryhydrazyl (DPPH) (,2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) (, and superoxide anion free radicals. Based on the B16 melanoma cell system, the effects of PPEO on the viability and morphology of B16 cells and the production of melanin were evaluated. The results revealed that PPEO at concentrations below 50 µg/mL could decrease the melanin content without affecting cell viability and morphology. Intracellular tyrosinase (TYR) activity and Western blot analysis showed that PPEO could down-regulate the expression level of TYR in B16 cells and dose-dependently inhibit TYR activity (by a maximum of 64.54%). Meanwhile, the main active components responsible for the effect are citral and ß-myrcene. In conclusion, PPEO has good anti-oxidant and anti-melanogenic activity, and thus can be widely used as a natural antioxidant in the food, pharmaceutical, and cosmetic industries.

Downregulation of α-Melanocyte-Stimulating Hormone-Induced Activation of the Pax3-MITF-Tyrosinase Axis by Sorghum Ethanolic Extract in B16F10 Melanoma Cells.

Ultraviolet irradiation-induced hyperpigmentation of the skin is associated with excessive melanin production in melanocytes. Tyrosinase (TYR) is a key enzyme catalyzing the rate-limiting step in melanogenesis. TYR expression is controlled by microphthalmia-associated transcription factor (MITF) expression. Sorghum is a cereal crop widely used in a variety of foods worldwide. Sorghum contains many bioactive compounds and is beneficial to human health. However, the effects of sorghum in anti-melanogenesis have not been well characterized. In this study, the biological activity of sorghum ethanolic extract (SEE) on α-melanocyte-stimulating hormone (α-MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated α-MSH-induced TYR gene promoter activity through the downregulation of the transcription factor MITF. We found that paired box gene 3 (Pax3) contributes to the maximal induction of MITF gene promoter activity. Further analysis demonstrated that SEE inhibited α-MSH-induced Pax3 expression. The collective results indicate that SEE attenuates α-MSH-induced TYR expression through the suppression of Pax3-mediated MITF gene promoter activity. Targeting the Pax3-MITF axis pathway could be considered a potential strategy to increase the efficacy of anti-melanogenesis.

The Dietary Supplement Chondroitin-4-Sulfate Exhibits Oncogene-Specific Pro-tumor Effects on BRAF V600E Melanoma Cells.

Dietary supplements such as vitamins and minerals are widely used in the hope of improving health but may have unidentified risks and side effects. In particular, a pathogenic link between dietary supplements and specific oncogenes remains unknown. Here we report that chondroitin-4-sulfate (CHSA), a natural glycosaminoglycan approved as a dietary supplement used for osteoarthritis, selectively promotes the tumor growth potential of BRAF V600E-expressing human melanoma cells in patient- and cell line-derived xenograft mice and confers resistance to BRAF inhibitors. Mechanistically, chondroitin sulfate glucuronyltransferase (CSGlcA-T) signals through its product CHSA to enhance casein kinase 2 (CK2)-PTEN binding and consequent phosphorylation and inhibition of PTEN, which requires CHSA chains and is essential to sustain AKT activation in BRAF V600E-expressing melanoma cells. However, this CHSA-dependent PTEN inhibition is dispensable in cancer cells expressing mutant NRAS or PI3KCA, which directly activate the PI3K-AKT pathway. These results suggest that dietary supplements may exhibit oncogene-dependent pro-tumor effects.

Anti-Melanogenic Properties of Greek Plants. A Novel Depigmenting Agent from Morus alba Wood.

In therapeutic interventions associated with melanin hyperpigmentation, tyrosinase is regarded as a target enzyme as it catalyzes the rate-limiting steps in mammalian melanogenesis. Since many known agents have been proven to be toxic, there has been increasing impetus to identify alternative tyrosinase inhibitors, especially from natural sources. In this study, we investigated 900 extracts from Greek plants for potential tyrosinase inhibitive properties. Among the five most potent extracts, the methanol extract of Morus alba wood (MAM) demonstrated a significant reduction in intracellular tyrosinase and melanin content in B16F10 melanoma cells. Bioassay-guided isolation led to the acquisition of twelve compounds: oxyresveratrol (1), kuwanon C (2), mulberroside A (3), resorcinol (4), dihydrooxyresveratol (5), trans-dihydromorin (6), 2,4,3'-trihydroxydihydrostilbene (7), kuwanon H (8), 2,4-dihydroxybenzaldehyde (9), morusin (10), moracin M (11) and kuwanon G (12). Among these, 2,4,3'-trihydroxydihydrostilbene (7) is isolated for the first time from Morus alba and constitutes a novel potent tyrosinase inhibitor (IC50 0.8 ± 0.15). We report here for the first time dihydrooxyresveratrol (5) as a potent natural tyrosinase inhibitor (IC50 0.3 ± 0.05). Computational docking analysis indicated the binding modes of six tyrosinase inhibitors with the aminoacids of the active centre of tyrosinase. Finally, we found both MAM extract and compounds 1, 6 and 7 to significantly suppress in vivo melanogenesis during zebrafish embryogenesis.

The Inhibitory Effect of Abietic Acid on Melanoma Cancer Metastasis and Invasiveness In Vitro and In Vivo.

Melanoma cell metastasis is the primary cause of patient death. Thus, various treatment strategies have been developed to prevent metastasis. Abietic acid (AA) is an organic compound commonly found in trees. This study is aimed to investigate the antimetastatic activity of AA in B16F10-xenografted C57BL/6 mice and assess the anticancer activity of AA in combination with Taxol in melanoma cells. AA effectively reduced the formation of lung metastases by approximately 92.8%. AA treatment inhibited migratory potential (p < 0.001), invasion (p < 0.001), and motility (p < 0.001) of highly metastatic B16F10 melanoma cells in vitro. Zymography revealed that AA reduced the proteinase activities of matrix metalloproteinase-2 and urokinase-type plasminogen activator. Molecular analyses showed that AA reduced Akt phosphorylation and activating protein-1 DNA-binding activity by Western blot and electrophoretic mobility shift assay (EMSA), respectively. In summary, AA effectively inhibited B16F10 lung metastasis, and 50[Formula: see text][Formula: see text]M AA did not affect the viability of B16F10 cells. AA improved the efficacy of Taxol and demonstrated strong anticancer activity on melanoma cells. These results suggested that AA could be used as an antimetastatic agent or as an adjuvant for anticancer therapy.

Trametinib in the treatment of melanoma.

INTRODUCTION: Aberrant MAPK pathway signaling is a hallmark of melanoma. Mitogen/extracellular signal-regulated kinase (MEK) 1/2 are integral components of MAPK signaling. Several MEK inhibitors have demonstrated activity as single agents and in combination with other therapies. Trametinib was the first MEK inhibitor approved for use in treatment of advanced BRAF(V600) mutant melanoma as a single agent and in combination with BRAF inhibitor, dabrafenib. AREAS COVERED: In this article, we discuss the underlying biology of MEK inhibition and its rationale in melanoma treatment with special emphasis on the clinical development of trametinib, from initial Phase I studies to randomized Phase II and III studies, both as monotherapy and in combination with other therapeutics. Furthermore, we briefly comment on trametinib for NRAS mutant and other non-BRAF mutant subsets of melanoma. EXPERT OPINION: Trametinib is a novel oral MEK inhibitor with clinical activity in BRAF(V600) mutant metastatic melanoma alone and in combination with dabrafenib. Trametinib is currently being explored in other genetic subsets as well, particularly those with NRAS mutations or atypical BRAF alterations. Furthermore, to maximize efficacy and overcome acquired resistance, studies evaluating the combination of trametinib with other targeted agents and immunotherapy are underway.

Oridonin induces apoptosis in uveal melanoma cells by upregulation of Bim and downregulation of Fatty Acid Synthase.

Oridonin is an orally available drug isolated from Traditional Chinese Medicine. Previous studies with oridonin have demonstrated broad-spectrum anticancer activity in a variety of cancer types. However, the effect of oridonin in uveal melanoma has not been addressed. In this study, we aimed to investigate whether oridonin elicited anticancer activity and its underlying mechanism in human uveal melanoma cells. We demonstrated that oridonin potently reduced cell viability, induced apoptosis and inhibited clonogenic survival and growth with single digit micromolar concentrations in uveal melanoma OCM-1 and MUM2B cell lines. We found that oridonin markedly increased the expression of proapoptotic Bcl-2 family protein Bim in uveal melanoma cells, and knockdown Bim by small interfering RNA significantly attenuated oridonin-induced cell death, indicating an essential role of Bim in oridonin-mediated anticancer activity. Additionally, we observed that oridonin suppressed Fatty Acid Synthase (FAS) expression in uveal melanoma cells, and enforced FAS expression by insulin partially rescued the cells from oridonin-induced apoptosis, showing that inhibition of FAS also contributed to oridonin-mediated apoptosis. Taken together, we reported that oridonin displays potent anticancer effect against uveal melanoma cells through upregulation of Bim and inhibition of FAS. Since oridonin is a popular anticancer agent, our study therefore may have translational implication on the management of patients with uveal melanoma.

[Effects of Xiaoyao Powder Extract in co-culture model of melanoma cells and keratinocytes on expression of tyrosinase and its related protein].

OBJECTIVE: To observe the effects and mechanism of Xiaoyao Powder extract on the content of melanin in co-culture model of melanoma cells and keratinocytes. METHODS: Eluting components of Xiaoyao Powder was collected by AB-8 macroporous resin column. Different concentration extracts of Xiaoyao Powder were added into the co-culture model of A375 melanoma cells and HaCat ke- ratinocytes. Hunt method was used to detected the content of melanin. RT-PCR assay was used to detect the effects of the extract of Xi- aoyao Powder on the TYR,TRP-1 and TRP-2 mRNA expression in A375 melanoma cells. RESULTS: Compared with the control group,the extract of Xiaoyao Powder down-regulated content of melanin and mRNA expression of TYR,TRP-1 and TRP-2 in A375 melanoma cells by 82.23% ,93. 01% and 29. 11% ,23.78% ,20. 05% ;25. 13% ,15.02% ,11.64% ,respectively(P < 0. 01). CONCLUSION: The extract of Xiaoyao Powder can decrease the melanogenesis by down-regulating the mRNA expression of tyrosinase and its related protein.

Melanoma expression of matrix metalloproteinase-23 is associated with blunted tumor immunity and poor responses to immunotherapy.

BACKGROUND: Matrix metalloproteinase-23 (MMP-23) can block the voltage-gated potassium channel Kv1.3, whose function is important for sustained Ca(2+) signaling during T cell activation. MMP-23 may also alter T cell activity and phenotype through cleavage of proteins affecting cytokine and chemokine signaling. We therefore tested the hypothesis that MMP-23 can negatively regulate the anti-tumor T cell response in human melanoma. METHODS: We characterized MMP-23 expression in primary melanoma patients who received adjuvant immunotherapy. We examined the association of MMP-23 with the anti-tumor immune response - as assessed by the prevalence of tumor-infiltrating lymphocytes and Foxp3(+) regulatory T cells. Further, we examined the association between MMP-23 expression and response to immunotherapy. Considering also an in trans mechanism, we examined the association of melanoma MMP-23 and melanoma Kv1.3 expression. RESULTS: Our data revealed an inverse association between primary melanoma MMP-23 expression and the anti-tumor T cell response, as demonstrated by decreased tumor-infiltrating lymphocytes (TIL) (P = 0.05), in particular brisk TILs (P = 0.04), and a trend towards an increased proportion of immunosuppressive Foxp3(+) regulatory T cells (P = 0.07). High melanoma MMP-23 expression is also associated with recurrence in patients treated with immune biologics (P = 0.037) but not in those treated with vaccines (P = 0.64). Further, high melanoma MMP-23 expression is associated with shorter periods of progression-free survival for patients receiving immune biologics (P = 0.025). On the other hand, there is no relationship between melanoma MMP-23 and melanoma Kv1.3 expression (P = 0.27). CONCLUSIONS: Our data support a role for MMP-23 as a potential immunosuppressive target in melanoma, as well as a possible biomarker for informing melanoma immunotherapies.

Honokiol affects melanoma cell growth by targeting the AMP-activated protein kinase signaling pathway.

BACKGROUND: Malignant melanoma is an aggressive form of skin cancer with limited effective therapeutic options. Melanoma research concentrates on maximizing the effect on cancer cells with minimal toxicity to normal cells. AMP-activated protein kinase (AMPK) is an important regulator of cellular energy homeostasis and has been shown to control tumor progression regulating the cell cycle, protein synthesis, and cell growth and/or survival. Honokiol (HNK) is a biphenolic compound derived from Magnolia officinalis, a plant that has been used in traditional Chinese and Japanese medicine for the treatment of various pathological conditions. Recent studies have shown that HNK has antitumor activity with relatively low toxicity. In this study, we demonstrated that the growth inhibitory effects of HNK on melanoma and melanoma cancer stem cells were mediated through the activation of AMPK and hence AMPK signaling in melanoma cells. METHODS: We determined the effects of HNK treatment on various melanoma cell lines. HNK-induced cell growth inhibitory effects were determined using hexosaminidase assay. Protein expression studies were done by immunoblotting. Primary spheroid assay was used to assess stemness by growing single suspension cells in ultralow attachment plates. RESULTS: HNK is highly effective in inhibiting melanoma cells by attenuating protein kinase B/mammalian target of rapamycin and AMPK signaling. HNK showed significant inhibition of the spheroid-forming capacity of melanoma cells and, hence, stemness. HNK significantly decreased the number and size of melanospheres in a dose-dependent manner. Western blot analyses showed enhanced phosphorylation of AMPK in melanoma cells. Furthermore, HNK decreased the cellular adenosine triphosphate pool in a dose-dependent manner with maximum effects observed at 48 hours. CONCLUSIONS: The results suggest that HNK can target melanoma cells and mark them for cell death through AMPK signaling. Further studies are warranted for developing HNK as an effective chemopreventive/therapeutic agent in melanoma.

Evaluation of anti-melanoma activities of (1S,2E,4R,6E,8R,11S,12R)-8,12-epoxy-2,6-cembradiene-4,11-diol, (1S,2E,4R,6E,8S,11R,12S)-8,11-epoxy-4,12-epoxy-2,6-cembradiene and (1S,4R,13S)-cembra-2E,7E,11E-trien-4,13-diol from the Red Sea soft coral Sarcophyton glaucum.

Three natural cembranoids from the Red Sea soft coral Sarcophyton glaucum namely (1S,2E,4R,6E,8R,11S,12R)-8,12-epoxy-2,6-cembradiene-4,11-diol, (1S,2E,4R,6E,8S,11R,12S)-8,11-epoxy-4,12-epoxy-2,6-cembradiene and (1S,4R,13S)-cembra-2E,7E,11E-trien-4,13-diol were evaluated for their inhibitory effects on mouse melanoma B16F10 cell growth. Results show that all the cembranoids strongly inhibit viability of melanoma cells particularly during 48 -72 hrs treatment and also inhibit de novo DNA synthesis and PARP activity and stimulate fragmentation of DNA. (1S,2E,4R,6E,8R,11S,12R)-8,12-epoxy-2,6-cembradiene-4,11-diol was not cytotoxic to monkey kidney CV-1 cells at the concentration that produces the anti-melanoma effects which indicates that this compound may be a good candidate for further development. (1S,2E,4R,6E,8S,11R,12S)-8,11-epoxy-4,12-epoxy-2,6-cembradiene and (1S,4R,13S)-cembra-2E,7E,11E-trien-4,13-diol were found to be cytotoxic to healthy cells.

Xanthoceraside induces apoptosis in melanoma cells through the activation of caspases and the suppression of the IGF-1R/Raf/MEK/ERK signaling pathway.

Xanthoceraside, a saponin extracted from the husks of Xanthoceras sorbifolia Bunge, suppresses inflammation and oxidative stress. However, the antitumor properties of xanthoceraside as well as its mechanism of action remain unclear. Therefore, we proposed to investigate its potential anticancer property. In this study, the viability of cells was measured by the MTT assay. Cell cycle and mitochondrial membrane potential were measured by flow cytometry, and the expressions of procaspase-9, procaspase-3, Cyto.c, Apaf-1, Bcl-2, Bcl-xL, Bad, p53, and IGF-1R/Raf/MEK/ERK were tested by Western blotting. Xanthoceraside significantly inhibited the proliferation of human melanoma A375.S2 cells in a concentration- and time-dependent manner but did not impair the viability of normal cells (peripheral blood mononuclear cells). Further analysis revealed that xanthoceraside induced apoptosis by activating caspase-3 and caspase-9 in a time-dependent manner through the mitochondrial pathway but did not activate caspase-8 in the cells. In addition, xanthoceraside inhibited the expression of the insulin-like growth factor-1 receptor (IGF-1R), which is an important prosurvival, antiapoptotic signaling growth factor receptor that is frequently overexpressed in cancer cells and used as a therapeutic target for multiple cancers. Interestingly, xanthoceraside also decreased the expression of Raf, p-MEK, and p-ERK, the downstream effectors of IGF-1R. Taken together, these findings indicate that xanthoceraside induces apoptosis through a mitochondria-mediated apoptotic pathway, which is induced by the downregulation of IGF-1R/Raf/MEK/ERK cascades in A375.S2 cells.

Spine venom of crown-of-thorns starfish (Acanthaster planci) induces antiproliferation and apoptosis of human melanoma cells (A375.S2).

The crown-of-thorns starfish (Acanthaster planci) is a venomous starfish. In this study, the extraction of A. planci spine venom (ASV) was performed by phosphate saline buffer, followed by assaying the cytotoxicity on human normal and tumor cells. It was found that human melanoma cells (A375.S2) were the most sensitive to the ASV solution. The cells, after incubation with ASV, significantly appeared to decrease cell viability and increase lactate dehydrogenase (LDH) release with a dose-dependent relationship. The extract of spine promoted loss of mitochondrial membrane potential (ΔΨm) and induced inter-nucleosomal DNA fragmentation in human melanoma cells. The cells exhibited apoptosis by using propidium iodide (PI) staining of DNA fragmentation; it was then determined by flow cytometry (sub-G1 peak). The molecular cytotoxicity of ASV was tested through evaluation of the apoptosis/necrosis ratio by double staining with annexin V and PI assay. The A. planci spine venom showed significant antiproliferation. The human melanoma cells revealed apoptosis at low dose (1.25 µg/ml), and necrosis occurred at high dose (5 µg/ml).

The protective effect of coffee consumption on cutaneous melanoma risk and the role of GSTM1 and GSTT1 polymorphisms.

PURPOSES: The authors examined the association between coffee consumption and cutaneous melanoma and the implication of GSTM1 and GSTT1 polymorphisms. METHODS: A hospital-based case-control study was conducted in the inpatient wards of IDI-San Carlo Rome, Italy, including 304 incident cases of cutaneous melanoma and 305 controls. Information on socio-demographic characteristics, medical history, smoking, sun exposure, pigmentary characteristics and diet was collected for all subjects. Within the study, individual patterns at two polymorphic genes (GSTM1 and GSTT1) belonging to glutathione S-transferases family were investigated in 188 cases of cutaneous melanoma and 152 controls. Logistic regression was the method used to estimate odds ratio and 95 % confidence intervals. RESULTS: High frequency of coffee drinking (>once daily), compared with low-frequency consumption of coffee (≤7 times weekly) was associated with a protective effect for cutaneous melanoma (OR 0.46; 95 % CI 0.31-0.68) after adjusting for sex, age, education, hair colour, common nevi, skin phototype, and sunburn episodes in childhood. When stratified by GSTM1 and GSTT1 genotype, the protective effect of coffee was extremely high for subjects with both GSTM1 and GSTT1 null polymorphisms (OR 0.01; 95 % CI 0.0003-0.54). CONCLUSIONS: Our results show a protective effect of coffee consumption for cutaneous melanoma, in particular for those with homozygous deletion for GSTM1 and GSTT1.

Recurrent BRAF kinase fusions in melanocytic tumors offer an opportunity for targeted therapy.

BRAF is the most prevalent oncogene and an important therapeutic target in melanoma. In some cancers, BRAF is activated by rearrangements that fuse its kinase domain to 5' partner genes. We examined 848 comparative genomic hybridization profiles of melanocytic tumors and found copy number transitions within BRAF in 10 tumors, of which six could be further characterized by sequencing. In all, the BRAF kinase domain was fused in-frame to six N-terminal partners. No other mutations were identified in melanoma oncogenes. One of the seven melanoma cell lines without known oncogenic mutations harbored a similar BRAF fusion, which constitutively activated the MAP kinase pathway. Sorafenib, but not vemurafenib, could block MAP kinase pathway activation and proliferation of the cell line at clinically relevant concentrations, whereas BRAF(V) (600E) mutant melanoma cell lines were significantly more sensitive to vemurafenib. The patient from whom the cell line was derived showed a durable clinical response to sorafenib.