lignans and Melanoma

Topics: Benzodioxoles; Dioxoles; Humans; Lignans; Melanoma; Phenols

Magnoliae Flos is a traditional herbal medicine used to treat nasal congestion associated with headache, empyema, and allergic rhinitis. In our preliminary screening of crude drugs used in Japanese Kampo formulas for melanin synthesis, the methanol extract of Magnoliae Flos was found to exhibit strong melanin synthesis activity. However, there have been no studies evaluating the effects of Magnoliae Flos or its constituents on melanogenesis. The present study aimed to isolate the active compounds from Magnoliae Flos that activate melanin synthesis in melanoma cells and three-dimensional human skin equivalent, and to investigate the molecular mechanism underlying melanin induction. The methanol extract of Magnoliae Flos induced an increase of melanin content in both B16-F1 and HMV-II cells. A comparison of melanin induction by three fractions prepared from the extract showed that the ethyl acetate fraction markedly induced melanin synthesis. Bioassay-guided separation of the ethyl acetate fraction resulted in the isolation of seven lignans (1:  - 7: ). Among them, (+)-magnolin (5: ) strongly induced melanin synthesis and intracellular tyrosinase activity. Furthermore, the ethyl acetate fraction and 5: clearly induced melanin content in a three-dimensional human skin equivalent. Molecular analysis revealed that 5: triggered the protein expression of tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2. Further analysis of transcriptional factors and signaling pathways demonstrated that 5: induces the protein expression of tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2 activated by the protein kinase A- and p38 mitogen-activated protein kinase-dependent pathways, leading to cAMP-responsive element-binding protein phosphorylation and microphthalmia-associated transcription factor expression. These findings demonstrate the potential of 5: as a potent therapeutic agent for hypopigmentation.

Topics: Animals; Cell Line, Tumor; Cyclic AMP-Dependent Protein Kinases; Humans; Lignans; Melanins; Melanoma; Melanoma, Experimental; Methanol; Microphthalmia-Associated Transcription Factor; Monophenol Monooxygenase; p38 Mitogen-Activated Protein Kinases; Signal Transduction

Honokiol (HK) is a natural bioactive compound with proven antineoplastic properties against melanoma. However, it shows very low bioavailability when administered orally. Alternatively, topical administration may offer a promising route. The objective of the current study was to fabricate HK transfersomes (HKTs) for topical treatment of melanoma. As an ultradeformable carrier system, transfersomes can overcome the physiological barriers to topical treatment of melanoma: the stratum corneum and the anomalous tumor microenvironment. Moreover, the immunomodulatory and stemness-regulation roles of HKTs were the main interest of this study.. TFs were prepared using the modified scalable heating method. A three-factor, three-level Box-Behnken design was utilized for the optimization of the process and formulation variables. Intracellular uptake and cytotoxicity of HKTs were evaluated in nonactivated and stromal cell-activated B16F10 melanoma cells to investigate the influence of the complex tumor microenvironment on the efficacy of HK. Finally, ELISA and Western blot were performed to evaluate the expression levels of TGF-β and clusters of differentiation (CD47 and CD133, respectively).. The optimized formula exhibited a mean size of 190 nm, highly negative surface charge, high entrapment efficiency, and sustained release profile. HKTs showed potential to alleviate the immunosuppressive characteristics of B16F10 melanoma in vitro via downregulation of TGF-β signaling. In addition, HKTs reduced expression of the "do not eat me" signal - CD47. Moreover, HKTs possessed additional interesting potential to reduce the expression of the stem-like cell marker CD133. These outcomes were boosted upon combination with metformin, an antihyperglycemic drug recently reported to possess different functions in cancer, while combination with collagenase, an extracellular matrix-depleting enzyme, produced detrimental effects.. HKTs represent a promising scalable formulation for treatment of the aggressive B16F10 melanoma, which is jam-packed with immunosuppressive and stem-like cell markers.

Topics: Antineoplastic Agents; Biphenyl Compounds; Humans; Lignans; Melanoma; Tumor Microenvironment

Gomisin A (G.A), a lignan compound extracted from the fruits of Schisandra chinensis, is known to exert anti-tumor effects on hepatocarcinoma and colorectal cancer cells. Suppression of proliferation and metastatic abilities of cancer cells are some effective cancer treatment methods.. The objective of this study is to investigate the effects of G.A on metastatic melanoma, and the mechanism by which it affects metastatic melanoma.. The anti-proliferative and anti-metastatic effects of G.A were observed in in vitro and in vivo.. WST assay and flow cytometry were conducted to investigate the effect of G.A on proliferation, cell cycle arrest, and apoptosis in metastatic melanoma cell lines. Migration and invasion abilities of G.A-treated melanoma cells were observed by wound healing and invasion assays.. G.A (25-100 μM) decreased the viability of melanoma cells by inducing cell cycle arrest and apoptosis. These anti-proliferative effects of G.A were found to be mediated by AMPK, ERK, and JNK activation. G.A (5-20 μM) decreased the migration and invasion of melanoma cells by suppressing epithelial-mesenchymal transition (EMT). Consequently, G.A (2-50 mg/kg) inhibited lung metastasis by suppressing EMT and inducing cell cycle arrest and apoptosis in melanoma cells.. These results conclude that G.A has the potential to reduce metastatic melanoma through its anti-proliferative and anti-metastatic effects.

Topics: AMP-Activated Protein Kinases; Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Cyclooctanes; Dioxoles; Epithelial-Mesenchymal Transition; Extracellular Signal-Regulated MAP Kinases; Humans; Lignans; Lung Neoplasms; MAP Kinase Kinase 4; Melanoma; Mice, Inbred C57BL; Xenograft Model Antitumor Assays

Melanoma is an aggressive form of skin cancer for which there are no effective drugs for prolonged treatment. The existing kinase inhibitor antiglycolytic drugs (B-Raf serine/threonine kinase or BRAF inhibitors) are effective for a short time followed by a rapid onset of drug resistance.. Here, we show that a mitochondria-targeted analog of magnolol, Mito-magnolol (Mito-MGN), inhibits oxidative phosphorylation (OXPHOS) and proliferation of melanoma cells more potently than untargeted magnolol. Mito-MGN also inhibited tumor growth in murine melanoma xenografts. Mito-MGN decreased mitochondrial membrane potential and modulated energetic and mitophagy signaling proteins.. Results indicate that Mito-MGN is significantly more potent than the FDA-approved OXPHOS inhibitor in inhibiting proliferation of melanoma cells.. These findings have implications in the treatment of melanomas with enhanced OXPHOS status due to metabolic reprogramming or drug resistance.

Topics: Animals; Autophagy; Biphenyl Compounds; Cell Line, Tumor; Cytoprotection; Humans; Lignans; Melanoma; Mice; Mice, Nude; Mitophagy; Nitric Oxide Synthase; Oxidative Phosphorylation

Malignant melanoma (MM) is one of the malignant tumors with highly metastatic and aggressive biological actions. Schizandrin A (SchA) is a bioactive lignin compound with strong anti-oxidant and anti-aging properties, which is stable at room temperature and is often stored in a cool dry place. Hence, we investigated the effects of SchA on MM cell line A375 and its underlying mechanism. A375 cells were used to construct an in vitro MM cell model. Cell viability, proliferation, apoptosis, and migration were detected by Cell Counting Kit-8, BrdU assay, flow cytometry, and transwell two-chamber assay, respectively. The cell cycle-related protein cyclin D1 and cell apoptotic proteins (Bcl-2, Bax, cleaved-caspase-3, and cleaved-caspase-9) were analyzed by western blot. Alteration of H19 expression was achieved by transfecting with pEX-H19. PI3K/AKT pathway was measured by detecting phosphorylation of PI3K and AKT. SchA significantly decreased cell viability in a dose-dependent manner. Furthermore, SchA inhibited cell proliferation and cyclin D1 expression. SchA increased cell apoptosis along with the up-regulation of pro-apoptotic proteins (cleaved-caspase-3, cleaved-caspase-9, and Bax) and the down-regulation of anti-apoptotic protein (Bcl-2). Besides, SchA decreased migration and down-regulated matrix metalloproteinases (MMP)-2 and MMP-9. SchA down-regulated lncRNA H19. Overexpression of H19 blockaded the inhibitory effects of SchA on A375 cells. SchA decreased the phosphorylation of PI3K and AKT while H19 overexpression promoted the phosphorylation of PI3K and AKT. SchA inhibited A375 cell growth, migration, and the PI3K/AKT pathway through down-regulating H19.

Topics: Apoptosis; Blotting, Western; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclooctanes; Down-Regulation; Gene Expression Regulation, Neoplastic; Humans; Lignans; Melanoma; MicroRNAs; Polycyclic Compounds; Real-Time Polymerase Chain Reaction; RNA, Long Noncoding; Signal Transduction

There is increasing global incidence of highly metastatic melanoma and therapeutic strategies like those focusing on the downstream beta-catenin/MITF axis of invading melanoma cells are urgently needed. Targeting endoplasmic reticulum (ER) stress can promote cancer cell death and inhibit epithelial mesenchymal transition (EMT) in metastatic tumors. This study aimed to determine if Honokiol could promote ER stress-dependent apoptosis and regulate metastatic melanoma. The therapeutic efficacy of Honokiol was assessed using the highly metastatic melanoma xenograft mouse model for peritoneal metastasis and evaluated by computed tomography imaging. The ER stress marker, Calpain-10, delineated a novel proteolytic cleavage enzyme, while CHOP/GADD153-regulated apoptosis was used for gene silencing to determine the role of the β-catenin/MITF axis in melanoma cells. The results showed that Honokiol effectively decreased peritoneal dissemination and organ metastasis via ER stress activation and EMT marker inhibition. Knockdown Calpain-10 or CHOP/GADD153 blocked all of the biological effects in Honokiol-induced β-catenin/MITF cleavage, ERSE or TCF/LEF luciferase activity, and β-catenin kinase activity. These findings suggest that Honokiol can significantly thwart the progression of highly metastatic melanoma using the β-catenin/MITF axis via prompt Calpain-10 and CHOP/GADD153 regulated cascades.

Topics: Animals; Antineoplastic Agents, Phytogenic; beta Catenin; Biphenyl Compounds; Calpain; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclin-Dependent Kinase 2; Endoplasmic Reticulum Stress; Gene Expression Regulation, Neoplastic; Humans; Lignans; Male; Melanoma; Mice, Inbred BALB C; Mice, Nude; Microphthalmia-Associated Transcription Factor; Peritoneal Neoplasms; Skin Neoplasms; Transcription Factor CHOP; Wnt Signaling Pathway; Xenograft Model Antitumor Assays

Topics: Cell Line, Tumor; Cell Survival; Comet Assay; Cytotoxins; DNA Damage; Humans; Lauraceae; Lignans; Melanoma; Micronucleus Tests; Plant Stems

Most BRAF-mutant melanoma patients experience a fulminate relapse after several months of treatment with BRAF/MEK inhibitors. To improve therapeutic efficacy, natural plant-derived compounds might be considered as potent additives. Here, we show that magnolol, a constituent of Magnolia officinalis, induced G1 arrest, apoptosis and cell death in BRAF- and NRAS-mutant melanoma cells at low concentration, with no effect in BRAF- and NRAS wild-type melanoma cells and human keratinocytes. This was confirmed in a 3D spheroid model. The apoptosis-inducing effect of magnolol was completely rescued by activating Akt suggesting a mechanism relying primarily on Akt signaling. Magnolol significantly downregulated the PI3K/Akt pathway which led to a global decrease of the active histone mark H3K4me3. Alongside, the repressive histone mark H3K9me3 was increased as a response to DNA damage. Magnolol-induced alterations of histone modifications are reversible upon activation of the Akt pathway. Magnolol-induced a synergistic effect in combination with either BRAF/MEK inhibitors dabrafenib/trametinib or docetaxel at a lower concentration than usually applied in melanoma patients. Combination of magnolol with targeted therapy or chemotherapy also led to analogous effects on histone marks, which was rescued by Akt pathway activation. Our study revealed a novel epigenetic mechanism of magnolol-induced cell death in melanoma. Magnolol might therefore be a clinically useful addition to BRAF/MEK inhibitors with enhanced efficacy delaying or preventing disease recurrence.

Topics: Apoptosis; Biphenyl Compounds; Cell Death; Cell Line, Tumor; Epigenesis, Genetic; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; GTP Phosphohydrolases; Humans; Lignans; Melanoma; Membrane Proteins; Models, Biological; Mutation; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins c-akt; Signal Transduction

Six neolignans including three previously undescribed metabolites: 1-[(7R)-hydroxy-8-propenyl]-3-[3'-methoxy-1'-(8'-propenyl)-phenoxy]-4,5-dimethoxybenzene, 4-hydroxy-5-methoxy-3-[3'-methoxy-1'-(8'-propenyl)phenoxy]-1-(7-oxo-8-propenyl)benzene and 4,5-dimethoxy-3-[3'-methoxy-1'-(8'-propenyl)phenoxy]-1-(7-oxo-8-propenyl)benzene were isolated from twigs of Nectandra leucantha Nees & Mart (Lauraceae) using bioactivity-guided fractionation. Cytotoxic activity of isolated compounds was evaluated in vitro against cancer cell lines (SK BR-3, HCT, U87-MG, A2058, and B16F10), being dehydrodieugenol B and 4-hydroxy-5-methoxy-3-[3'-methoxy-1'-(8'-propenyl)phenoxy]-1-(7-oxo-8-propenyl)benzene the most active metabolites. These compounds displayed IC

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Cell Line, Tumor; Humans; Lauraceae; Lignans; Melanoma; Membrane Potential, Mitochondrial; Mice; Mitochondria; Molecular Structure; Oxidation-Reduction

Honokiol, a plant lignan has been shown to have antineoplastic effects against nonmelanoma skin cancer developments in mice. In this study, antineoplastic effects of honokiol were investigated in malignant melanoma models. In vitro effects of honokiol treatment on SKMEL-2 and UACC-62 melanoma cells were evaluated by measuring the cell viability, proliferation, apoptosis, cell cycle analysis, and expressions of various proteins associated with cell cycle progression and apoptosis. For the in vivo study, male nude mice inoculated with SKMEL-2 or UACC-62 cells received injections of sesame oil or honokiol for two to seven weeks. In vitro honokiol treatment caused significant decrease in cell viability, proliferation, cell cycle arrest, increased apoptosis, and modulation of apoptotic and cell cycle regulatory proteins. Honokiol caused an accumulation of cells in the G2/M phase of the cell cycle in SKMEL-2 and G0/G1 phase in UACC-62 cells. An elevated level of caspases and PARP were observed in both cell lines treated with honokiol. A decrease in the expression of various cell cycle regulatory proteins was also observed in honokiol treated cells. Honokiol caused a significant reduction of tumor growth in SKMEL-2 and UACC-62 melanoma xenografts. These findings suggest that honokiol is a good candidate for further studies as a possible treatment for malignant melanoma.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Biphenyl Compounds; Cell Cycle; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; Humans; Lignans; Male; Melanoma; Mice; Mice, Nude; Neoplasm Proteins; Xenograft Model Antitumor Assays

Overexpression of NADPH oxidase 1 (Nox1) in melanoma cells is often associated with increased migration/metastasis rate. To develop effective treatment options, we have examined the effect of honokiol, a phytochemical from Magnolia plant, on the migratory potential of human melanoma cell lines (A375, Hs294t, SK-Mel119 and SK-Mel28) and assessed whether Nox1 is the target. Using an in vitro cell migration assay, we observed that treatment of different melanoma cell lines with honokiol for 24 h resulted in a dose-dependent inhibition of cell migration that was associated with reduction in Nox1 expression and reduced levels of oxidative stress. Treatment of cells with N-acetyl-L-cysteine, an anti-oxidant, also inhibited the migration of melanoma cells. Treatment of cells with diphenyleneiodonium chloride, an inhibitor of Nox1, significantly decreased the migration ability of Hs294t and SK-Mel28 cells. Further, we examined the effect of honokiol on the levels of core proteins (p22(phox) and p47(phox)) of the NADPH oxidase complex. Treatment of Hs294t and SK-Mel28 cells with honokiol resulted in accumulation of the cytosolic p47(phox) protein and decreased levels of the membrane-bound p22(phox) protein, thus blocking their interaction and inhibiting Nox1 activation. Our in vivo bioluminescence imaging data indicate that oral administration of honokiol inhibited the migration/extravasation and growth of intravenously injected melanoma cells in internal body organs, such as liver, lung and kidney in nude mice, and that this was associated with an inhibitory effect on Nox1 activity in these internal organs/tissues.

Topics: Animals; Apoptosis; Biphenyl Compounds; Blotting, Western; Cell Membrane; Cell Movement; Cell Proliferation; Cytosol; Enzyme Inhibitors; Female; Fluorescent Antibody Technique; Humans; Lignans; Melanoma; Mice; Mice, Nude; NADPH Oxidase 1; NADPH Oxidases; Oxidative Stress; Protein Binding; Reactive Oxygen Species; Tumor Cells, Cultured; Wound Healing; Xenograft Model Antitumor Assays

The majority of human melanomas bears BRAF mutations and thus is treated with inhibitors of BRAF, such as vemurafenib. While patients with BRAF mutations often demonstrate an initial dramatic response to vemurafenib, relapse is extremely common. Thus, novel agents are needed for the treatment of these aggressive melanomas. Honokiol is a small molecule compound derived from Magnolia grandiflora that has activity against solid tumors and hematopoietic neoplasms. In order to increase the lipophilicity of honokiol, we have synthesized honokiol DCA, the dichloroacetate ester of honokiol. In addition, we synthesized a novel fluorinated honokiol analog, bis-trifluoromethyl-bis-(4-hydroxy-3-allylphenyl) methane (hexafluoro). Both compounds exhibited activity against A375 melanoma in vivo, but honokiol DCA was more active. Gene arrays comparing treated with vehicle control tumors demonstrated induction of the respiratory enzyme succinate dehydrogenase B (SDHB) by treatment, suggesting that our honokiol analogs induce respiration in vivo. We then examined its effect against a pair of melanomas, LM36 and LM36R, in which LM36R differs from LM36 in that LM36R has acquired vemurafenib resistance. Honokiol DCA demonstrated in vivo activity against LM36R (vemurafenib resistant) but not against parental LM36. Honokiol DCA and hexafluoro inhibited the phosphorylation of DRP1, thus stimulating a phenotype suggestive of respiration through mitochondrial normalization. Honokiol DCA may act in vemurafenib resistant melanomas to increase both respiration and reactive oxygen generation, leading to activity against aggressive melanoma in vivo.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Biphenyl Compounds; Cell Line, Tumor; Drug Resistance, Neoplasm; Humans; Indoles; Lignans; Melanoma; Mice; Signal Transduction; Sulfonamides; Vemurafenib; Xenograft Model Antitumor Assays

Melanoma is an aggressive disease with limited therapeutic options. Here, we determined the effects of honokiol (HNK), a biphenolic natural compound on melanoma cells and stemness. HNK significantly inhibited melanoma cell proliferation, viability, clonogenicity and induced autophagy. In addition, HNK significantly inhibited melanosphere formation in a dose dependent manner. Western blot analyses also demonstrated reduction in stem cell markers CD271, CD166, Jarid1b, and ABCB5. We next examined the effect of HNK on Notch signaling, a pathway involved in stem cell self-renewal. Four different Notch receptors exist in cells, which when cleaved by a series of enzymatic reactions catalyzed by Tumor Necrosis Factor-α-Converting Enzyme (TACE) and γ-secretase protein complex, results in the release of the Notch intracellular domain (NICD), which then translocates to the nucleus and induces target gene expression. Western blot analyses demonstrated that in HNK treated cells there is a significant reduction in the expression of cleaved Notch-2. In addition, there was a reduction in the expression of downstream target proteins, Hes-1 and cyclin D1. Moreover, HNK treatment suppressed the expression of TACE and γ-secretase complex proteins in melanoma cells. To confirm that suppression of Notch-2 activation is critical for HNK activity, we overexpressed NICD1, NICD2, and performed HNK treatment. NICD2, but not NICD1, partially restored the expression of Hes-1 and cyclin D1, and increased melanosphere formation. Taken together, these data suggest that HNK is a potent inhibitor of melanoma cells, in part, through the targeting of melanoma stem cells by suppressing Notch-2 signaling.

Topics: ADAM Proteins; ADAM17 Protein; Amyloid Precursor Protein Secretases; Autophagy; Basic Helix-Loop-Helix Transcription Factors; Biomarkers, Tumor; Biphenyl Compounds; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin D1; Homeodomain Proteins; Humans; Lignans; Melanoma; Neoplastic Stem Cells; Receptor, Notch2; Receptors, Notch; Signal Transduction; Transcription Factor HES-1

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.. 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.. 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.. 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.

Topics: AMP-Activated Protein Kinases; Antineoplastic Agents, Phytogenic; Biphenyl Compounds; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Humans; Immunoblotting; Lignans; Melanoma; Melanoma, Cutaneous Malignant; Microscopy, Electron, Scanning; Signal Transduction; Skin Neoplasms

Melanomas are aggressive neoplasms with limited therapeutic options. Therefore, developing new therapies with low toxicity is of utmost importance. Honokiol is a natural compound that recently has shown promise as an effective anticancer agent.. The effect of honokiol on melanoma cancer cells was assessed in vitro. Proliferation and physiologic changes were determined using hexosaminidase assay and transmission electron microscopy. Protein expression was assessed by immunoblotting.. Honokiol treatment inhibited cell proliferation and induced death. Electron microscopy showed autophagosome formation. Reduced levels of cyclin D1 accompanied cell-cycle arrest. Honokiol also decreased phosphorylation of AKT (known as protein kinase B) and mammalian target of rapamycin, and inhibited γ-secretase activity by down-regulating the expression of γ-secretase complex proteins, especially anterior pharynx-defective 1.. Honokiol is highly effective in inhibiting melanoma cancer cells by attenuating AKT/mammalian target of rapamycin and Notch signaling. These studies warrant further clinical evaluation for honokiol alone or with present chemotherapeutic regimens for the treatment of melanomas.

Topics: Amyloid Precursor Protein Secretases; Animals; Antineoplastic Agents, Phytogenic; Autophagy; Biomarkers, Tumor; Biphenyl Compounds; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Dose-Response Relationship, Drug; Down-Regulation; Immunoblotting; Lignans; Melanoma; Mice; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases

Melanoma continues to be a therapeutic challenge for the medical community owing to the scarcity of effective agents available to treat the disease. Honokiol, a traditional Chinese herb, has been proven to have anti-cancer effects in various cell types, therefore we hypothesized it may have similar cytotoxic capabilities against melanoma cells in vitro.. Two cell lines, SK-MEL2 and MeWo, were grown in culture and exposed to increasing doses of Honokiol. Cell proliferation, cytochrome c release into the cytosol, intra-cellular caspase activity, and mitochondrial depolarization were then evaluated after treatment with honokiol.. Melanoma cells in culture underwent cell death, had increased cytosolic cytochrome c, showed greater caspase activity, and demonstrated increased mitochondrial depolarization after treatment when compared to controls.. It appears that honokiol is an effective inhibitor of cultured human melanoma cells.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Biphenyl Compounds; Blotting, Western; Caspases; Cell Proliferation; Cytochromes c; Drugs, Chinese Herbal; Enzyme-Linked Immunosorbent Assay; Humans; In Vitro Techniques; Lignans; Melanoma; Tumor Cells, Cultured

In this study, we confirmed that sesamin, an active lignan isolated from sesame seed and oil, is a novel skin-tanning compound. The melanin content and tyrosinase activity were increased by sesamin in a dose-dependent manner in B16 melanoma cells. The mRNA and protein levels of tyrosinase were also enhanced after the treatment with sesamin. Western blot analysis revealed that sesamin induced and sustained up-regulation of microphthalmia-associated transcription factor (MITF). Sesamin could activate cAMP response element (CRE) binding protein (CREB), but it had no effect on the phosphorylation of p38 mitogen-activated protein kinase (MAPK) or Akt. Moreover, sesamin activated protein kinase A (PKA) via a cAMP-dependent pathway. Consistent with these results, sesamin-mediated increase of melanin synthesis was reduced significantly by H-89, a PKA inhibitor, but not by SB203580, a p38 MAPK inhibitor or by LY294002, a phosphatidylinositol-3-kinase (PI3K) inhibitor. Sesamin-mediated phosphorylation of CREB and induction of MITF and tyrosinase expression were also inhibited by H-89. These findings indicated that sesamin could stimulate melanogenesis in B16 cells via the up-regulation of MITF and tyrosinase, which was, in turn, due to the activation of cAMP signaling.

Topics: Animals; Antioxidants; Cyclic AMP; Dioxoles; Lignans; Melanoma; Melanosomes; Mice; Microphthalmia-Associated Transcription Factor; Monophenol Monooxygenase; Signal Transduction; Up-Regulation

Intracellular cAMP stimulates microphthalmia-associated transcription factor (MITF) induction in melanocytes through cAMP-responsive element binding protein (CREB), which plays a pivotal role in the gene expression of tyrosinase for melanin biosynthesis. In the present study, saucerneol D as a lignan constituent of Saururus chinensis (Saururaceae family) efficiently inhibited melanin production with IC(50) values of 188-297 nM in B16 melanoma cells stimulated with α-melanocyte stimulating hormone (α-MSH) or other cAMP elevators. Moreover, saucerneol D down-regulated α-MSH-induced gene expression of tyrosinase at the transcription level in B16 cells, but it did not directly inhibit the catalytic activity of cell-free tyrosinase. As to the molecular basis of hypopigmenting action, saucerneol D inhibited α-MSH-induced phosphorylation of CREB in the cells, and sequentially suppressed MITF induction. Taken together, this study provides saucerneol D down-regulated the gene expression of tyrosinase, resulting in the inhibition of cAMP-induced melanin biosynthesis, and suggests pharmacological potential of the lignan structure in skin hyperpigmentation.

Topics: alpha-MSH; Cell Survival; Cyclic AMP; Cyclic AMP Response Element-Binding Protein; Down-Regulation; Drug Evaluation, Preclinical; Gene Expression; Hormones; Humans; Hyperpigmentation; Lignans; Luciferases; Melanins; Melanocytes; Melanoma; Melanoma, Experimental; Microphthalmia-Associated Transcription Factor; Monophenol Monooxygenase; Phosphorylation; Saururaceae

(-)-Cubebin showed a melanogenesis stimulation activity in a concentration-dependent manner in murine B16 melanoma cells without any significant effects on cell proliferation. Tyrosinase activity was increased at 24-72 h after addition of cubebin to B16 cells, and then intracellular melanin amount was increased at 48-96 h after the treatment. The expression levels of tyrosinase were time-dependently enhanced after the treatment with cubebin. At the same time, the expression levels of tyrosinase mRNA were also increased after addition of cubebin. Furthermore Western blot analysis revealed that cubebin elevated the level of phosphorylation of p38 mitogen-activated protein kinase (MAPK). SB203580, a selective inhibitor of p38 MAPK, completely blocked cubebin-induced expression of tyrosinase mRNA in B16 cells. These results suggested that cubebin increased melanogenesis in B16 cells through the enhancement of tyrosinase expression mediated by activation of p38 MAPK.

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Enzymologic; Imidazoles; Lignans; Melanins; Melanoma; Mice; Monophenol Monooxygenase; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Pyridines; RNA, Messenger

Six lignans, including the cyclolignan 3,4'-dihydroxy-3',4'-dimethoxy-6,7'-cyclolignan, were isolated from the flowering tops of Larrea tridentata. Additionally the flavanone, (S)-4',5-dihydroxy-7-methoxyflavanone, was isolated for the first time from L. tridentata or any member of the family Zygophyllaceae. All of the compounds were assessed for their growth inhibitory activity against human breast cancer, human colon cancer and human melanoma cell lines. The lignans had IC50 values of 5-60 microM with the linear butane-type lignans being the most potent, and it was found that colon cancer cells were the least sensitive cell type tested. The relative potency of linear butane type lignans against human breast cancer appears to correlate positively with the number of O-methyl groups present on the molecule.

Topics: Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cell Line, Tumor; Colonic Neoplasms; Humans; Inhibitory Concentration 50; Larrea; Lignans; Melanoma; Molecular Structure

Larrea tridentata (Moc & Sess) Cov. (Zygophyllaceae) is an ethnobotanically important plant found in the American Southwest and northern Mexico. Although numerous beneficial effects have been attributed to this plant, several case reports have demonstrated high doses of Larrea-containing herbals induce hepatotoxicity and nephrotoxicity in humans. Nordihydriguaiaretic acid (NDGA) is a lignan found in high amounts (up to 10% by dry weight) in the leaves and twigs of L. tridentata. Previously, NDGA has been shown to induce cystic nephropathy in the rat, however, no reports have been made concerning this compound's hepatotoxic potential. Here, we report that intraperitoneal administration of NDGA is lethal in the mouse (LD(50)=75 mg/kg). Administration is associated with a time and dose-dependent increase in serum alanine aminotransferase levels, which suggest liver damage. Indeed, freshly isolated mouse hepatocytes are more sensitive to NDGA than human melanoma cells. Furthermore, we have identified glucuronidation as a potential detoxification mechanism for NDGA. Both mono and diglucuronide conjugates of NDGA are formed after intravenous dosing. The monoglucuronide is also formed after incubation of NDGA with human hepatic microsomes; suggesting that glucuronide conjugation is important in the metabolism of NDGA by humans. In summary, this report indicates that NDGA may contribute to the hepatotoxicity of L. tridentata and provides preliminary information on NDGA metabolism.

Topics: Alanine Transaminase; Animals; Antioxidants; Cell Survival; Chemical and Drug Induced Liver Injury; Dose-Response Relationship, Drug; Female; Hepatocytes; Humans; Inactivation, Metabolic; Injections, Intraperitoneal; Larrea; Lignans; Masoprocol; Melanoma; Mice; Mice, Inbred BALB C; Microsomes, Liver; Plant Components, Aerial; Plant Extracts; Time Factors; Tumor Cells, Cultured