A375 Melanoma Cells Research Articles

The Inhibitory Effect of Polyphenon 60 from Green Tea on Melanin and Tyrosinase in Zebrafish and A375 Human Melanoma Cells.

Polyphenon 60 (PP60) from green tea has long been used as an antioxidant, anticancer, antimicrobial, and antimutagenic. Aim of the Study. To investigate tyrosinase inhibition-related kinetic mechanism and antimelanogenesis potential of PP60. Materials and Methods. The effect of PP60 on melanin and tyrosinase was evaluated in A375 melanoma cells and zebrafish embryos. The melanoma cells were treated with 20, 40, and 60 µg/mL of PP60, and tyrosinase expression was induced by using L-DOPA. The western blot method was used for the evaluation of tyrosinase expression. Cell lysates were prepared from treated and untreated cells for cellular tyrosinase and melanin quantification. Furthermore, zebrafish embryos were treated with 20, 40, and 60 µg/mL of PP60 and reference drug kojic acid for determination of depigmentation and melanin quantification. In vitro assays were also performed to examine the impact of PP60 on mushroom tyrosinase activity. To determine cytotoxicity, MTT was used against melanoma cell line A375. Results. PP60 showed good tyrosinase inhibitory activity with an IC50 value of 0.697 ± 0.021 µg/mL as compared to kojic acid a reference drug with an IC50 value of 2.486 ± 0.085 µg/mL. Kinetic analysis revealed its mixed type of inhibition against mushroom tyrosinase. In addition, western blot analysis showed that at 60 µg/mL dose of PP60 significantly reduced L-DOPA-induced tyrosinase expression in melanoma cells. PP60 significantly inhibits the cellular tyrosinase (p < 0.05) and reduces the melanin (p < 0.05) contents of melanoma cells. Furthermore, PP60 was found to be very potent in significantly reducing the zebrafish embryos' pigmentation (p < 0.05) and melanin (p < 0.05) content at the dose of 60 µg/mL. Conclusions. Our results demonstrate that PP60 has a strong potency to reduce pigmentation. It may be useful for the cosmetic industries to develop skin whitening agents with minimal toxic effects.

Novel Triterpenic Acid-Benzotriazole Esters Act as Pro-Apoptotic Antimelanoma Agents.

Pentacyclic triterpenes, such as betulinic, ursolic, and oleanolic acids are efficient and selective anticancer agents whose underlying mechanisms of action have been widely investigated. The introduction of N-bearing heterocycles (e.g., triazoles) into the structures of natural compounds (particularly pentacyclic triterpenes) has yielded semisynthetic derivatives with increased antiproliferative potential as opposed to unmodified starting compounds. In this work, we report the synthesis and biological assessment of benzotriazole esters of betulinic acid (BA), oleanolic acid (OA), and ursolic acid (UA) (compounds 1–3). The esters were obtained in moderate yields (28–42%). All three compounds showed dose-dependent reductions in cell viability against A375 melanoma cells and no cytotoxic effects against healthy human keratinocytes. The morphology analysis of treated cells showed characteristic apoptotic changes consisting of nuclear shrinkage, condensation, fragmentation, and cellular membrane disruption. rtPCR analysis reinforced the proapoptotic evidence, showing a reduction in anti-apoptotic Bcl-2 expression and upregulation of the pro-apoptotic Bax. High-resolution respirometry studies showed that all three compounds were able to significantly inhibit mitochondrial function. Molecular docking showed that compounds 1–3 showed an increase in binding affinity against Bcl-2 as opposed to BA, OA, and UA and similar binding patterns compared to known Bcl-2 inhibitors.

Imiquimod-induced ROS production causes lysosomal membrane permeabilization and activates caspase-8-mediated apoptosis in skin cancer cells

BackgroundLysosomal cell death is induced by lysosomal membrane permeabilization (LMP) and the subsequent release of lysosomal proteolytic enzymes, including cathepsins (CTSs), which results in mitochondrial dysfunction and apoptosis. Imiquimod (IMQ), a synthetic TLR7 ligand, has both antiviral and antitumor activity against various skin malignancies in clinical treatment. Previously, we demonstrated IMQ not only caused lysosomal dysfunction but also triggered lysosome biogenesis to achieve lysosomal adaptation in cancer cells. ObjectiveTo determine whether lysosomes are involved in IMQ-induced apoptosis. MethodsThe human skin cancer cell lines BCC, A375 and mouse melanoma cell line B16F10 were used in all experiments. Cell death was determined by the Cell Counting Kit-8 (CCK-8) assay and DNA content assay. Protein expression was determined by immunoblotting. Caspase-8 activity was assessed using a fluorescence caspase-8 kit and determined by flow cytometry and confocal microscopy. ResultsIMQ not only induced lysosome damage but also abrogated lysosome function in skin cancer cells. IMQ-induced caspase-8 activation contributed to the processes of lysosomal cell death. Moreover, the use of ROS scavengers significantly abolished caspase-8 activation and inhibited IMQ-induced LMP. Additionally, pharmacological inhibition of CTSD not only abrogated caspase-8 activation but also rescued IMQ-induced cell death. Finally, lysosome-alkalizing agents enhanced the cytotoxicity of IMQ in vitro and in vivo. ConclusionsIMQ-induced ROS accumulation promotes LMP, releases CTSs into the cytosol, stimulates caspase-8 activation and finally causes lysosomal cell death. Lysosomal cell death and the CTSD/caspase-8 axis may play a crucial role in IMQ-induced cell death.

Production of rutile titanium dioxide nanoparticles by trans-ferulic acid and their biomedical applications

Titanium dioxide nanoparticles (TiO2NPs) are popular materials with high annual production and increasing applications in different fields. In the current research, we synthesized TiO2NPs with the help of the reducing potential of trans-ferulic acid (FA). FA-TiO2NPs are principally characterized by X-Ray Diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-Ray Analysis (EDX), and Thermogravimetric (TGA) techniques. Then, their biomedical properties were investigated by in vitro hemolysis, anti-inflammatory, and cytotoxicity tests. According to physiochemical analysis, FA-TiO2NPs had mostly rod-shaped morphology with a rutile crystallographic phase. These NPs were non-hemolytic with high anti-denaturation and membrane stabilization activity and thus excellent in vitro anti-inflammatory effects. FA-TiO2NPs decreased the cell viability of A375 (melanoma cell line), MCF-7 (breast cancer cell line), and human skin fibroblast (normal cell line) in a dose-dependent manner. The IC50 values of FA-TiO2NPs were above 12.5, 25, and 50 µg/mL against A375, MCF-7, and skin fibroblast cell lines, respectively. In this study, we demonstrated the biocompatibility and valuable potential of FA-TiO2NPs in biomedical applications.

The Histone Deacetylase Inhibitor ITF2357 (Givinostat) Targets Oncogenic BRAF in Melanoma Cells and Promotes a Switch from Pro-Survival Autophagy to Apoptosis.

Histone deacetylase inhibitors (HDACI) are epigenetic compounds that have been widely considered very promising antitumor agents. Here, we focus on the effects of the pan-HDAC inhibitor ITF2357 (Givinostat) in comparison with SAHA (Vorinostat) in melanoma cells bearing BRAF V600E oncogenic mutation. Our results indicate both ITF2357 and SAHA dose-dependently reduce the viability of BRAF-mutated SK-MEL-28 and A375 melanoma cells. The comparison of IC50 values revealed that ITF2357 was much more effective than SAHA. Interestingly, both inhibitors markedly decreased oncogenic BRAF protein expression levels, ITF2357 being the most effective compound. Moreover, the BRAF decrease induced by ITF2357 was accompanied by a decrease in the level of phospho-ERK1/2. The inhibitor of upstream MEK activity, U0126, reduced ERK1/2 phosphorylation and dramatically potentiated the antitumor effect of ITF2357, exacerbating the reduction in the BRAF level. ITF2357 stimulated an early pro-survival autophagic response, which was followed by apoptosis, as indicated by apoptotic markers evaluation and the protective effects exerted by the pan-caspase inhibitor z-VADfmk. Overall, our data indicate for the first time that ITF2357 targets oncogenic BRAF in melanoma cells and induces a switch from autophagy to classic apoptosis, thus representing a possible candidate in melanoma targeted therapy.

Design, synthesis, and biological screening of a series of 4′-fluoro-benzotriazole-acrylonitrile derivatives as microtubule-destabilising agents (MDAs)

Introduction: Colchicine-binding site inhibitors are some of the most interesting ligands belonging to the wider family of microtubule-destabilising agents. Results: A novel series of 4′-fluoro-substituted ligands (5–13) was synthesised. The antiproliferative activity assays resulted in nM values for the new benzotriazole-acrylonitrile derivatives. Compound 5, the hit compound, showed an evident blockade of HeLa cell cycle in the G2-M phase, but also a pro-apoptotic potential, and an increase of early and late apoptotic cells in HeLa and MCF-7 cell cycle analysis. Confocal microscopy analysis showed a segmented shape and a collapse of the cytoskeleton, as well as a consistent cell shrinkage after administration of 5 at 100 nM. Derivative 5 was also proved to compete with colchicine at colchicine-binding site, lowering its activity against tubulin polymerisation. In addition, co-administration of 5 and doxorubicin in drug-resistant A375 melanoma cell line highlighted a synergic potential in terms of inhibition of cell viability. Discussion: The 4′-fluoro substitution of benzotriazole-acrylonitrile scaffold brought us a step forward in the optimisation process to obtain compound 5 as promising MDA antiproliferative agent at nanomolar concentration.

The molecular mechanisms of vulpinic acid induced programmed cell death in melanoma.

Malignant melanoma is an aggressive skin tumor with a rapidly increasing incidence and there is not yet a successful treatment strategy. Vulpinic acid (VA) is derived from secondary metabolites from lichen species. In the current study, we, for the first time, investigated the anti-cancer effects of VA and the underlying mechanism VA induced programmed cell death in melanoma. The anti-cancer effects of VA on melanoma cells were evaluated by the xCELLigence system, flow cytometry, caspase-3 activity and RT-PCR analysis. Our results showed that VA had a strong anti-proliferative effect on A-375 melanoma cells without damaging human epidermal melanocyte cells. Additionally, VA promoted apoptotic cell death through G2/M arrest and the activation of both intrinsic and extrinsic apoptosis pathways according to the analysis of 88 genes associated with apoptosis by qRT-PCR. Our findings suggest that VA could become an alternative topical and transdermal treatment strategy in the treatment of maligned melanoma cancer. However, further investigations are needed to assess the underlying molecular mechanism of VA mediated apoptotic cell death in the treatment of melanoma.

Glycoside oleandrin downregulates toll-like receptor pathway genes and associated miRNAs in human melanoma cells

Melanoma accounts for the majority of skin cancer-related deaths. Nerium oleander is a plant known to be toxic and consumed due to the cardiac glycosides it contains. Oleandrin is a cardiac glycoside obtained from of N. oleander. Beside capable of inhibiting proliferation and metastasis of cancer cells, cardiac glycoside derivative compounds cause cardiovascular side effects. Because of cardiovascular toxicity of clinically used cardiac glycosides, it is necessary to investigate cardiac glycoside derivative compounds capable of inhibiting proliferation and metastasis of cancer cells.It is known that oleandrin has anticarcinogenic effects in other cancers. Previous studies have shown that toll-like receptors (TLRs) and their related microRNAs (miRNAs) are associated with cancer. Therefore, aim was to investigate the effect of oleandrin on genes and miRNAs associated with TLRs in A375 melanoma cells in this study. The effects of oleandrin on cell viability, cytokines, apoptosis were evaluated using XTT, ELISA and TUNEL analyses, respectively. The effect of oleandrin on expression of TLR genes and 5 associated miRNAs in A375 cells has been determined by qRT-PCR. In addition, the levels of MyD88, TLR2 and TLR4 proteins were analyzed by western blot method.ELISA indicated that oleandrin treatment (47 nM at 48 h) reduced the level of proinflammatory cytokine IFNG. TUNEL analysis showed that apoptosis rate was significantly increased in the oleandrin dose group. According to qRT-PCR results, there was a significant decrease in IRAK1, IRAK4, MyD88, TLR2-TLR7 and TRAF3 expressions in the oleandrin treated group compared to the control (untreated cell). Also, a significant decrease in TLR4 protein expression has been observed. In addition, oleandrin significantly downregulated the levels of hsa-miRNA-146a-5p and hsa-miRNA-21-5p.In conclusion, it has been observed that oleandrin has an effect on TLR pathway-related genes and miRNAs in melanoma cells. We show that TLRs pathways and hsa-miR-146a-5p and hsa-miR-21-5p can participate in the oleandrin molecular mechanism of action.

Annona cherimola Mill. Leaf Extracts Affect Melanoma Cells Growth and Progression.

Cancer represents one of the major causes of mortality worldwide; indeed, 19.3 million new cases and almost 10.0 million deaths were estimated last year. Among the different type of cancers, malignant melanoma represents the most aggressive and deadly skin cancer. Unfortunately, the long-term efficacy of melanoma treatments is limited by the lack of clinical efficacy, onset of side effects and resistance. The latter is a major obstacle for the success of the melanoma therapy; thus, the exploration of new potent and safer anticancer agents is of great importance. Recently, numerous plant species, used for therapeutic purposes and containing various non-toxic nutraceuticals have been widely studied. Herein, we investigated the antioxidant and anticancer properties on melanoma cells of the ethanolic, methanolic and aqueous Annona cherimola leaf extracts (ACE, ACM and ACW, respectively). The ethanolic extract showed higher anticancer activity, mostly against the malignant A2058 melanoma cell line (IC50 = 5.6 ± 0.8 ng/mL), together with a very low activity on the normal cells. It blocks the melanoma cells migration process, and induces a clear disorganization of cytoskeleton, triggering cell apoptosis. Finally, some bioactive compounds were identified in the studied extracts.

MiR-767-3p suppresses melanoma progression by inhibiting ASF1B expression

BackgroundMelanoma, the type of skin cancer considered as most malignant, and known to be linked with a high incidence as well as high mortality rate. Although the dysregulation of ASF1B and miR-767-3p expression is involved in the progression of various cancers, their biological function in melanoma remains unclear. MethodsReal-time qPCR was the primary source for determining the levels of ASF1B and miR-767-3p in melanoma. For the validation of association among miR-767-3p and ASF1B, luciferase activity assay was used. Quantification of cell apoptosis, proliferation, migration and viability in melanoma cells were carried out by flow cytometry, BrdU, transwell assays, and CCK-8, respectively. Further evaluation of tumor growth was achieved by xenograft in vivo. ResultsResults showed an increased expression of ASF1B while declined expression of miR-767-3p in melanoma. ASF1B knockdown repressed cell migration, viability, proliferation, and tumor growth whereas boosted apoptosis in A375 as well as in A875 melanoma cells. Moreover, miR-767-3p attenuated the migration and proliferation of melanoma cells and encouraged cell apoptosis by reducing ASF1B levels. ConclusionIn this study, miR-767-3p was shown to inhibit ASF1B which will attenuate melanoma tumorigenesis, and by this it can be a potential new effective biomarker for the treatment of melanoma.

Bone Marrow Mesenchymal Stem Cell (BMSC) Downregulates Vascular Endothelial Growth Factor (VEGF) and Promotes the Apoptosis of Melanoma Cells

This study assessed BMSC’s effect on melanoma cells. The melanoma A375 cells were assigned into blank group, BMSC group, ERK agonist group, AKT agonist group, ERK + AKT agonist group and ERK + AKT repressor group followed by analysis of VEGF expression, cell apoptotic rate, and the expression of MEK/ERK and PI3K/AKT signal proteins. ERK and AKT agonist group showed highest VEGF expression, lowest cell apoptosis and Bcl-2 and Bcl-2/Bax expression as well as highest MEK/ERK and PI3K/AKT signaling proteins followed by ERK agonist group and AKT agonist group. The apoptosis of melanoma cells could be prompted by BMSC which might be through restraining the activity of MEK/ERK and PI3K/AKT signal pathway. In conclusion, the apoptosis of melanoma cells is prompted by BMSC through restraining the activity of MEK/ERK and PI3K/AKT signal pathway, indicating that BMSC might be used as a novel approach for the treatment of melanoma.

The mechanism of Tanshinone ⅡA on regulating EMT in cutaneous melanoma A375 cells through TAMs autophagy

The mechanism of Tanshinone ⅡA on regulating EMT in cutaneous melanoma A375 cells through TAMs autophagy

Quinolines and Oxazino-quinoline Derivatives as Small Molecule GLI1 Inhibitors Identified by Virtual Screening.

A virtual screening approach based on a five-feature pharmacophoric model for negative modulators of GLI1 was applied to databases of commercially available compounds. The resulting quinoline derivatives showed significant ability to reduce the GLI1 protein level and were characterized by submicromolar antiproliferative activity toward human melanoma A375 and medulloblastoma DAOY cell lines. Decoration of the quinoline ring and chemical rigidification to an oxazino-quinoline scaffold allowed us to deduce SAR considerations for future ligand optimization.

639 Identification of experimental therapeutics overcoming NRAS-based BRAFi-resistant malignant melanoma targeting brain metastases in a bioluminescent murine model

Molecularly targeted therapeutics have revolutionized the treatment of BRAFV600E-driven malignant melanoma, but the rapid development of resistance to BRAF kinase inhibitors (BRAFi) presents a significant obstacle. Here, we describe the identification of experimental melanoma therapeutics overcoming NRAS-based BRAFi-resistance employing a stringent genetic model of BRAFi-resistance, i.e. isogenic melanoma cell lines that differ only by NRAS mutational status (BRAFi-sensitive A375-BRAFV600E/NRASQ61 versus BRAFi-resistant A375 BRAFV600E/NRASQ61K). As a result of unbiased candidate screening, the clinical antimalarial mefloquine (MQ) was the only apoptogenic agent causing BRAFi-resistant A375 melanoma cell death at low micromolar concentrations. Comparative gene expression-array analysis (A375-BRAFV600E/NRASQ61 versus A375-BRAFV600E/NRASQ61K) revealed that MQ is a dual inducer of endoplasmic reticulum (ER) and redox stress responses that precede MQ-induced loss of viability. ER-trackerTM DPX fluorescence imaging and electron microscopy indicated ER swelling, accompanied by rapid induction of ER stress signaling (phospho-eIF2α, XBP-1s, ATF4). Fluo-4 AM-fluorescence indicated the occurrence of cytosolic calcium overload observable within seconds of MQ exposure. In a bioluminescent murine model employing intracranial injection of A375-Luc2 (BRAFV600E/NRASQ61K), an oral MQ regimen efficiently antagonized growth of brain metastases. Taken together, these data suggest feasibility of identifying valid candidates for drug repurposing aiming at chemotherapeutic elimination of malignant melanoma cells targeting BRAFV600E/NRASQ61K cells even if metastasized to the brain.

Influencing Mechanism of Nod-Like Receptor Protein 3 Inflammasome Activation in A375 Cell Activity in Human Cutaneous Malignant Melanoma.

This work was to investigate mechanism by which mir-22 targeting nod-like receptor protein 3 (NLRP3) inflammasome affected activity of human skin malignant melanoma (MM) A375 cells. Twenty-four mice were rolled into a control group (Group X) and an experimental group (Group Y) randomly. Without treatment in Group X, Group Y established MM model. After cell transfection, the mice were divided into group A (blank group), group B (negative group), group C (miR-22 mimics group), group D (miR-22 inhibitor group), and group E (miR-22 inhibitor+siNLRP3 group). The results were summarized as follows. The level of miR-22 mRNA in Group Y was obviously lower than that in Group X, and levels of NLRP3 and caspase-1 mRNA and NLRP3 and caspase-1 protein in Group Y were greatly higher than those in Group X (P < 0.05). The mRNA levels of miR-22 mRNA in group C were much higher in contrast to those in group A, and the mRNA levels of NLRP3 and caspase-1 were lower. The contrast results in group D and group A were the opposite, P < 0.05. The levels of NLRP3 and caspase-1 proteins in group C were greatly elevated, and those in group D were decreased compared with those in group A (P < 0.05). Therefore, miR-22 may target and inhibit the activation of the NLRP3 inflammasome to reduce the activity of cutaneous malignant melanoma A375 cells.

Onset of p53/NF-κB signaling crosstalk in human melanoma cells in response to anti-cancer theabrownin.

As a major tea component, theabrownin represents a promising anti-cancer candidate. However, its effect on the melanoma is unknown. To evaluate the in vitro and in vivo anti-melanoma efficacy of TB, we conducted cell viability, immunostaining, comet, and TUNEL assays on human A375 melanoma cells, and employed a zebrafish xenograft model of A375 cells. Real-time PCR (qPCR) and western blot were conducted to explore the molecular mechanisms of TB. In vitro, TB significantly inhibited the proliferation of A375 cells, and A375 cells showed the highest inhibitory rate among the other melanoma cell line (A875) and human dermal fibroblasts. TB triggered DNA damage and induced apoptosis of A375 cells and significantly inhibited the growth of A375 xenograft tumors in zebrafishes. Several key molecular events were activated by TB, including DNA damage-associated p53 and NF-κB pathways, through up-regulation of GADD45α, γ-H2A.X, phospho-ATM(p-ATM), phospho-ATR (p-ATR), phospho-p53 (p-p53), phospho-IKKα/β (p-IKKα/β), phospho-p65 (p-p65), etc. However, the TB-activated molecular events were counteracted by either knockdown of p53 or p65, and only dual knockdown of both p53 and p65 completed counteracted the anti-melanoma efficacy of TB. In conclusion, TB triggered DNA damage and thereby inhibited proliferation and induced cellular senescence and apoptosis of melanoma cells through mechanisms mediated by p53/NF-κB signaling crosstalk. This is the first report on the efficacy and mechanisms of TB on melanoma cells, making TB a promising candidate for anti-melanoma agent development.

Newly Substituted Anilino-Fluoroquinolones with Proliferation Inhibition Potential against a Panel of Cancer Cell Lines.

From a chemistry point of view, we hypothesized that superlative dual cytotoxicity-radical scavenging bioefficacies of series 4 FQs correlate to their acidic groups and C8-C7 ethylene diamine Chelation Bridge. Newly synthesized 16 lipophilic-acid chelating FQs have been screened for in vitro duality of proliferation inhibition and radical scavenging capacities. Substantially in LPS prompted RAW264.7 macrophages inflammation, IC50 values (µM) in the ascending order of new FQs' NO scavenging/antiinflammation capacity were 4e<4b<3d<4f<5c0.05). In comparison to classical and robust antineoplastic agent cisplatin and unlike triazoloFQs; nitroFQs (3a, 3b and 3f) and the reduced FQs (4a, 4c, 4d and 4e) exerted antiproliferation IC50 values <50 µM in leukaemia K562. Besides nitroFQ 3, the reduced FQs (4c and 4f) exhibited antineoplastic IC50 values <50 µM in lung A549 carcinoma. NitroFQ 3c and reduced FQs 4b, 4c, and 4f in breast MCF7 and reduced 4c in pancreatic PANC1 had reduction of viability IC50 values <50 µM. NitroFQ 3e, reduced FQs 4b and, 4c and triazoloFQ 5a exerted antiproliferation IC50 values <50 µM in breast T47D cells. Also nitroFQ 3e, reduced FQ 4c and triazoloFQ 5f exhibited antineoplastic IC50 values <50 µM in PC3 prostate cancer cells. Exceptionally triazoloFQ 5a, but neither nitro- nor reduced FQs, had cytotoxicity IC50 value <50 µM in resistant melanoma A375 cells. Unequivocally 4b antineoplastic effectiveness linked with its radical scavenging and antiinflammation effects while 3d and 5c lacked matching antiproliferation potentialities to their exquisite antiinflammation capacities. Explicitly reduced 4e and 4f exerted antiinflammation-selective cytotoxicity duality in vitro. Collectively, this work reveals lipophilic-acidic chelator FQs as authentic agents for the repurposing approach in anticancer chemotherapy/prevention.

Anti-melanogenesis effect from Wampee fruit pectin via α-MSH/TRY pathway in A375 cells

BackgroundPolysaccharides from wampee have been reported to process various biological activities, while the relationship between structure and bioactivities has been barely addressed. Pectin, an abundant water-soluble polysaccharide in wampee, showed significant antioxidant activity, which was associated with the anti-melanogenic activity. Therefore, this study investigated the physicochemical characteristics and the anti-melanogenesis effect of pectin extracted from wampee fruit in A375 cells.MethodsThe physicochemical characterization of pectin from wampee fruit was investigated by gel chromatography (GCP), FT-IR spectroscopy, and NMR spectroscopy methods. The anti-melanogenesis effects and mechanism were evaluated by mushroom tyrosine enzyme and human melanin cell model in vitro.ResultsThe results showed that a molecular weight of 5.271 × 105 Da wampee fruit pectin (WFP) were mainly composed of mannose (Man), ribose (Rib), rhamnose (Rha), glucuronic acid (Glc A), glucose (Glc), galacturonic acid (Gal A), galactose (Gal), and arabinose (Ara), which linked with →4)-β-D-Galp-(1 → units. The current study revealed that WFP could significantly suppress mushroom TRY activity in vitro. Furtherly, WFP significantly reduced intracellular and extracellular melanin formation in A375 melanoma cells depending on the presence of alpha-melanocyte stimulating hormone (α-MSH). TRY activity was only inhibited in α-MSH treated A375 cells. Western blot analysis demonstrated that WFP reverse α-MSH induced melanogenesis in A375 melanoma cells, including in down-regulated TRY, TYRP-1, TYRP-2, MITF and CREB expressions.ConclusionThese results indicated that WFP could inhibit α-MSH induced melanogenesis in A375 melanoma cells via α-MSH/TRY pathway. In conclusion, these data provided a new perspective to annotate WFP anti-melanogenesis activity mechanism.

Synergistic antitumor effect of a penicillin derivative combined with thapsigargin in melanoma cells

To investigate the effect of TAP7f, a penicillin derivative previously characterized as a potent antitumor agent that promotes ER stress and apoptosis, in combination with thapsigargin, an ER stress inducer, on melanoma cells. The synergistic antiproliferative effect of TAP7f in combination with thapsigargin was studied in vitro in murine B16-F0 melanoma cells, and in human A375 and SB2 melanoma cells. In vivo assays were performed with C57BL/6J mice challenged with B16-F0 cells. Immunofluorescence and Western blot assays were carried out to characterize the induction of ER stress and apoptosis. Necrotic tumor areas and the potential toxicity of the combined therapy were examined by histological analysis of tissue sections after hematoxylin-eosin staining. In vitro, the combination of TAP7f with thapsigargin synergistically inhibited the proliferation of murine B16-F0, and human A375 and SB2 melanoma cells. When non-inhibitory doses of each drug were simultaneously administered to C57BL/6J mice challenged with B16-F0 cells, a 50% reduction in tumor volumes was obtained in the combined group. An apoptotic response characterized by higher expression levels of Baxenhanced PARP-1 cleavage and the presence of active caspase 3 was observed in tumors from the combined treatment. In addition, higher expression levels of GADD153/CHOP and ATF4 were found in tumors of mice treated with both drugs with respect to each drug used alone, indicating the induction of an ER stress response. No signs of tissue toxicity were observed in histological sections of different organs extracted from mice receiving the combination. The synergistic and effective antitumor action of TAP7f in combination with thapsigargin could be considered as a potential therapeutic strategy for melanoma treatment.

Modulation of A375 human melanoma cell proliferation and apoptosis by nitric oxide

The present study aimed to assess the effect of NO• on melanoma A375 cell growth and apoptotic cell death. Trypan blue exclusion assay was employed to detect the cytotoxicity induced by controlled steady-state concentrations (given in µM • min) of NO•. The characteristics of the cellular cell cycle and apoptosis in NO•-treated A375 cells were also analyzed by Annexin V/PI and DNA fragmentation assays. Western blotting was applied to detect the expression of apoptosis-related proteins (p53, Bax, Fas, DR5, caspase-3 and -9, and PARP). When exposed to preformed 100% NO• for 8 h reactor system, a cumulative dose of 3360 μM • min reduced the viability by 22% 24 h after treatment and promoted apoptosis, 2.9- and 12.2-folds 24 and 48 h after treatment higher than the argon control, respectively. Cell cycle analysis 48 h after treatment revealed S-phase arrest in cells treated with 3360 μM • min NO•. It was also observed that the expression of p53, DR5, caspase 9 and PARP increased significantly upon NO• treatment. In addition, the present study assessed the inhibitory effects of endogenous NO• on the proliferation of human melanoma cells by employing specific (AMG, 1400W and/or SMTC) and nonspecific (NMA) NO• synthase (NOS) inhibitors resulting in melanoma cell growth inhibition; the highest cytotoxic effect was seen when inducible NOS inhibition by 1 mM 1400W treatment. Collectively, the present data suggest that NO• is involved in a key mechanism limiting melanoma proliferation and apoptosis, which may play in improving the efficacy of melanoma treatment.