Melanotic Cell Research Articles

Bovine Renal Lipofuscinosis in a Tanzanian Crossbred Yearling Male Calf: A Case Report

Aim: To report a rare case of bovine renal lipofuscinosis (BRL) that was encountered incidentally at necropsy. Presentation of the Case: In June 2023 an yearling male calf was found dead in one of the dairy cattle farms in Mbeya city, Tanzania; after being sick for about a week. The owner requested a necropsy service to establish the cause of the death of the animal. Necropsy revealed significant gross pathological changes in a liver that was cooked-like and shrunken, with flabby consistence and large pale necrotic foci. Furthermore, dark blue discoloration of both kidneys with normal morphology was evident. Based on the history and gross pathological findings, the animal was diagnosed to have died from acute hepatitis. Differential diagnosis for kidney discoloration included hemachromatosis, renal hemosiderosis, BRL, and melanotic renal cell carcinoma (MRCC). After ruling out hemachromatosis, renal hemosiderosis and MRCC in the list of possible causes of kidney discoloration based on the lack of gross pathological findings, particularly hepatic fibrosis, pallor, and a mass of tumor tissue in the kidneys that are characteristic of hemachromatosis, renal hemosiderosis and MRCC, respectively; the cause of kidney discoloration was diagnosed as BRL. Discussion: In this necropsy, the history and gross pathology suggested that the animal’s death could be attributed to acute liver failure, which is one of the sequelae of acute hepatitis. Kidney discoloration was not considered an attribute factor to the animal’s death because, with the exception of discoloration, the kidneys did not have gross pathological changes. Moreover, to date there has been no report of a clinical disease in cattle associated with BRL. However, BRL is an important disorder because it leads to condemnation of the affected kidneys as unfit for human consumption. Conclusion: The case of BRL reported here was an incidental finding at necropsy, and is not associated with the death of the animal.

The Assessment of Anti-Melanoma Potential of Tigecycline-Cellular and Molecular Studies of Cell Proliferation, Apoptosis and Autophagy on Amelanotic and Melanotic Melanoma Cells.

High mortality, aggressiveness, and the relatively low effectiveness of therapy make melanoma the most dangerous of skin cancers. Previously published studies presented the promising therapeutic potential of minocycline, doxycycline, and chlortetracycline on melanoma cells. This study aimed to assess the cytotoxicity of tigecycline, a third-generation tetracycline, on melanotic (COLO 829) and amelanotic (A375) melanoma cell lines. The obtained results showed that tigecycline, proportionally to the concentration and incubation time, efficiently inhibited proliferation of both types of melanoma cells. The effect was accompanied by the dysregulation of the cell cycle, the depolarization of the mitochondrial membrane, and a decrease in the reduced thiols and the levels of MITF and p44/42 MAPK. However, the ability to induce apoptosis was only found in COLO 829 melanoma cells. A375 cells appeared to be more resistant to the treatment with tigecycline. The drug did not induce apoptosis but caused an increase in LC3A/B protein levels-an autophagy marker. The observed differences in drug action on the tested cell lines also involved an increase in p21 and p16 protein levels in melanotic melanoma, which was related to cell cycle arrest in the G1/G0 phase. The greater sensitivity of melanotic melanoma cells to the action of tigecycline suggests the possibility of considering the use of the drug in targeted therapy.

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

The 10boron neutron-capture therapy (BNCT) is an emerging antitumoral method that shows increasing biomedical interest. BNCT is based on the selective accumulation of the 10boron isotope within the tumor, which is then irradiated with low-energy thermal neutrons, generating nuclear fission that produces 7lithium, 4helium, and γ rays. Simple catechol-borate esters have been rather overlooked as precursors of melanin biosynthesis, and therefore, a proof-of-concept approach for using dopamine-borate (DABO) as a suitable boron-containing candidate for potential BNCT is presented here. DABO can spontaneously oxidize and autopolymerize in vitro, giving a soluble, eumelanin-like brown-black poly-DABO product. Melanotic melanoma cell cultures treated with 1 mM DABO for 24 and 48 h were viable and showed no signs of damage or cell death. The stability and possible trans-esterification of DABO is shortly discussed. Chemical calculations and quantitative structure-activity relationships (QSAR) analysis of DABO and the BNCT agent BPA indicated that they should be cell permeant and accumulate within lysosomes and melanosomes. Molecular modeling allows visualization of both the DABO precursor and the structure of a borate derivative of the proposed catechol-porphycene model for eumelanin, showing interesting features from molecular orbital calculations. The main difference between DABO and other agents, such as BPA, is that it is not a boronic acid nor a boron cluster. This simple catechol-borate ester (protected from oxidation and blackening) could be administrated to living cells and organisms, in which biosynthesis of boron-melanin in melanoma melanocytes can lead to improved BNCT.

Mitochondrial function is controlled by melatonin and its metabolites in vitro in human melanoma cells

Melanoma is a leading cause of cancer deaths worldwide. Although immunotherapy has revolutionized the treatment for some patients, resistance towards therapy and unwanted side effects remain a problem for numerous individuals. Broad anti-cancer activities of melatonin are recognized; however, additional investigations still need to be elucidated. Herein, using various human melanoma cell models, we explore in vitro the new insights into the regulation of melanoma by melatonin and its metabolites which possess, on the other side, high safety profiles and biological meaningful. In this study, using melanotic (MNT-1) and amelanotic (A375, G361, Sk-Mel-28) melanoma cell lines, the comparative oncostatic responses, the impact on melanin content (for melanotic MNT-1 melanoma cells) as well as the mitochondrial function controlled by melatonin, its precursor (serotonin), a kynuric (N1 -acetyl-N2 -formyl-5-methoxykynuramine, AFMK) and indolic pathway (6-hydroxymelatonin, 6(OH)MEL and 5-methoxytryptamine, 5-MT) metabolites were assessed. Namely, significant disturbances were observed in bioenergetics as follows: (i) uncoupling of oxidative phosphorylation (OXPHOS), (ii) attenuation of glycolysis, (iii) dissipation of mitochondrial transmembrane potential (mtΔΨ) accompanied by (iv) massive generation of reactive oxygen species (ROS), and (v) decrease of glucose uptake. Collectively, these results together with previously published reports provide a new biological potential and make an imperative to consider using melatonin or its metabolites for complementary future treatments of melanoma-affected patients; however, these associations should be additionally investigated in clinical setting.

Effects of curcumin based PDT on the viability and the organization of actin in melanotic (A375) and amelanotic melanoma (C32) – in vitro studies

Curcumin is a turmeric, antioxidative compound, well-known of its anti-cancer properties. Nowadays more and more effort is made in the field of enhancing the efficiency of the anticancer therapies. Combining the photoactive properties of curcumin with the superficial localization of melanoma and photodynamic therapy (PDT) seems to be a promising treatment method.The research focused on the evaluation of the curcumin effectiveness as an anticancer therapeutic agent in the in vitro treatment of melanotic (A375) and amelanotic (C32) melanoma cell lines. Keratinocytes (HaCat) and fibroblasts (HGF) were used to assess the impact of the therapy on the skin tissue. The aim of the study was to investigate the cell death after exposure to light irradiation after preincubation with curcumin. Additionaly the authors analized the interactions between curcumin and the actin cytoskeleton.The cytotoxic effect initiated by curcumin and increased by irradiation confirm the usefulness of the flavonoid in the PDT approach. Depending on curcumin concentration and incubation time, melanoma cells survival rate ranged from: 93.68 % (C32 cell line, 10 μM, 24 h) and 83.47 % (A375 cell line, 10 μM, 24 h) to 8.98 % (C32 cell line, 50 μM, 48 h) and 12.42 % (A375 cell line, 50 μM, 48 h). Moreover, photodynamic therapy with curcumin increased the number of apoptotic and necrotic cells in comparison to incubation with curcumin without irradiation. The study demonstrated that PDT induced caspase-3 overexpression and DNA cleavage in the studied cell lines. The cells revealed decreased proliferation after the therapy due to the actin cytoskeleton rearrangement. Although effective, the therapy remains not selective towards melanoma cells.

Cellular and Molecular Aspects of Anti-Melanoma Effect of Minocycline-A Study of Cytotoxicity and Apoptosis on Human Melanotic Melanoma Cells.

Minocycline is a tetracycline compound with pleiotropic pharmacological properties. In addition to its antibacterial action, it shows many non-antimicrobial effects, including an anti-cancer activity. The anti-cancer action was confirmed in studies on ovarian carcinoma cells, hepatocellular carcinoma cells, glioma cells, or acute myeloid leukemia cells. Malignant melanoma remains a serious medical problem despite the extensive knowledge of the disease. The low effectiveness of the standard treatment, as well as the resistance to therapy, result in high mortality rates. This work aimed to investigate the potential and mechanisms of anti-melanoma action of minocycline. Human skin melanotic melanoma cell line COLO 829 was used in the study. The obtained results showed that minocycline decreased cell viability and inhibited the growth of melanoma cells, proportional to the drug concentration as well as to the time of incubation. The EC50 values were calculated to be 78.6 µM, 31.7 µM, and 13.9 µM for 24 h, 48 h, and 72 h, respectively. It was observed that treated cells had a disturbed cell cycle and significantly changed morphology. Moreover, minocycline caused a decrease in mitochondrial membrane potential and an increase in cells with a low level of reduced thiols. Finally, it was found that the anti-melanoma effect of minocycline was related to the induction of apoptosis. The drug activated caspases 8, 9, and 3/7 as well as increased the number of annexin V-positive cells. The presented results show that minocycline possesses anti-melanoma potential.

Cytotoxic Effect of Vanicosides A and B from Reynoutria sachalinensis Against Melanotic and Amelanotic Melanoma Cell Lines and in silico Evaluation for Inhibition of BRAFV600E and MEK1.

Vanicosides A and B are the esters of hydroxycinnamic acids with sucrose, occurring in a few plant species from the Polygonaceae family. So far, vanicosides A and B have not been evaluated for anticancer activity against human malignant melanoma. In this study, we tested these two natural products, isolated from Reynoutria sachalinensis rhizomes, against two human melanoma cell lines (amelanotic C32 cell line and melanotic A375 cell line, both bearing endogenous BRAFV600E mutation) and two normal human cell lines—keratinocytes (HaCaT) and the primary fibroblast line. Additionally, a molecular docking of vanicoside A and vanicoside B with selected targets involved in melanoma progression was performed. Cell viability was studied using an MTT assay. A RealTime-Glo™ Annexin V Apoptosis and Necrosis assay was used for monitoring programmed cell death (PCD). Vanicoside A demonstrated strong cytotoxicity against the amelanotic C32 cell line (viability of the C32 cell line was decreased to 55% after 72 h incubation with 5.0 µM of vanicoside A), significantly stronger than vanicoside B. This stronger cytotoxic activity can be attributed to an additional acetyl group in vanicoside A. No significant differences in the cytotoxicity of vanicosides were observed against the less sensitive A375 cell line. Moreover, vanicosides caused the death of melanoma cells at concentrations from 2.5 to 50 µM, without harming the primary fibroblast line. The keratinocyte cell line (HaCaT) was more sensitive to vanicosides than fibroblasts, showing a clear decrease in viability after incubation with 25 µM of vanicoside A as well as a significant phosphatidylserine (PS) exposure, but without a measurable cell death-associated fluorescence. Vanicosides induced an apoptotic death pathway in melanoma cell lines, but because of the initial loss of cell membrane integrity, an additional cell death mechanism might be involved like permeability transition pore (PTP)-mediated necrosis that needs to be explored in the future. Molecular docking indicated that both compounds bind to the active site of the BRAFV600E kinase and MEK-1 kinase; further experiments on their specific inhibitory activity of these targets should be considered.

Synthesis and Biological Evaluation of Acridine/Acridone Analogs as Potential Anticancer Agents.

The lack of efficacious therapy for advanced melanoma and neuroblastoma makes new approaches necessary. Therefore, many scientists seek new, more effective, more selective and less toxic anticancer drugs. We propose the synthesis of the new functionalized analogs of 1-nitroacridine/4- nitroacridone connected to tuftsin/retro-tuftsin derivatives as potential anticancer agents. Acridine and acridone analogues were prepared by Ullmann condensation and then cyclization reaction. As a result of nucleophilic substitution reaction 1-nitro-9-phenoxyacridine or 1- chloro-4-nitro-9(10H)-acridone with the corresponding peptides, the planned acridine derivatives (10a-c, 12, 17-a-d, 19) have been obtained. The cytotoxic activity of the newly obtained analogs were evaluated against melanotic (Ma) and amelanotic (Ab) melanoma cell lines and neuroblastoma SH-SY5Y by using the XTT method. Apoptosis and cell cycle were analyzed by flow cytometry. Among the investigated analogs compound 12 exhibited the highest potency comparable to dacarbazine action for amelanotic Ab melanoma cells. FLICA test (flurochrome-labeled inhibitors of caspases) showed that this analog significantly increased the content of cells with activated caspases (C+) among both neuroblastoma lines and only Ab melanoma line. Using phosphatidylserine (PS) externalization assay, 12 induced changes in the Ab melanoma plasma membrane structure as the externalization of phosphatidylserine (An+ cells). These changes in neuroblastoma cells were less pronounced. Analog 12 could be proposed as the new potential chemotherapeutic against amelanotic melanoma form especially.

Inhibitory effects of methanol extracts of selected plants on proliferation of two human melanoma cell lines

Purpose: The aim of the current study was to investigate the in vitro antiproliferative activity of methanolic extracts of six plants regardless of their claimed ethnopharmacological application.Methods: Methanol extracts of different parts of Glycyrrhizaglabra L. (Licorice), Matricaria chamomilla L. (Chamomile), Salvia triloba L. (Sage), Rheum palmatum L. (Rhubarb), Trigonella foenum-graecum L. (Fenugreek) and Sambucusebulus L. (Dwarf Elder) were prepared. The antiproliferative effects of the extracts were tested on two skin cancer melanoma cell lines namely A375.S2 (low tyrosinase expression) and WM 136.1A (high tyrosinase expression) using MTT assay. The IC50 values for the active extracts were determined against the two melanoma cell lines.Results: The methanolic extracts of G.glabra, M. chamomilla, S. triloba, R. palmatum inhibited the melanotic WM1361A proliferation in a dose-dependent manner revealing IC50 values of 35.2, 25.2, 20.6, 17.8, μg/ml, respectively but not A375.S2 cell line. However, the extracts of T. foenum-graecum and S. ebulus did not exhibit any significant cytotoxic activity on both melanoma cell lines.Conclusion: The results of these experiments show that methanol extracts of licorice, chamomile, sage and rhubarb have significant antiproliferative activity onWM1361A cell line; a representative human melanotic melanocyte tumor cell line. This renders these plants as potential sources of new lead compounds for the development of new drugs for melanoma cancer.Keywords: Melanoma, Plant extract, tyrosinase, Licorice, Chamomile, Sage, Rhubarb, WM1361A

Caffeine modulates growth and vitality of human melanotic COLO829 and amelanotic C32 melanoma cells: Preliminary findings

Coffee is one of the most popular beverages consumed worldwide and therefore even small effects of coffee bioactive compounds on cellular homeostasis could have a large impact on public health. Recent cohort health studies have shown an impressive inverse correlation between caffeinated coffee consumption and malignant melanoma risk. The aim of presented study was to examine the effect of caffeine on cell viability and glutathione status of melanotic (COLO829) and amelanotic (C32) melanoma cell lines as well as normal human melanocytes. Cell viability was determined by WST-1 colorimetric assay and then confirmed by the cytometry analysis with NucleoCounter® NC-3000™. The intracellular level of reduced thiols was determined by the use of the fluorescence-based image cytometer. The obtained results indicate the ability of caffeine to induce reduced thiols depletion and pro-apoptotic effect selectively in melanoma cells. The COLO829 cell line was shown to be more susceptible to studied methylxanthine in comparison to C32 cells. These data may support, for the first time, the recent epidemiological studies and provide the basis for further research into the mechanism of chemopreventive properties of caffeine.

Inhibitory effects of methanol extracts of selected plants on the proliferation of two human melanoma cell lines

Purpose: The aim of the current study was to investigate the in vitro antiproliferative activity of methanolic extracts of six plants regardless of their claimed ethnopharmacological application. Methods: Methanol extracts of different parts of Glycyrrhizaglabra L. (Licorice), Matricaria chamomilla L. (Chamomile), Salvia triloba L. (Sage), Rheum palmatum L. (Rhubarb), Trigonella foenum-graecum L. (Fenugreek) and Sambucusebulus L. (Dwarf Elder) were prepared. The antiproliferative effects of the extracts were tested on two skin cancer melanoma cell lines namely A375.S2 (low tyrosinase expression) and WM 136.1A (high tyrosinase expression) using MTT assay. The IC 50 values for the active extracts were determined against the two melanoma cell lines. Results: The methanolic extracts of G.glabra , M. chamomilla , S. triloba , R. palmatum inhibited the melanotic WM1361A proliferation in a dose-dependent manner revealing IC 50 values of 35.2, 25.2, 20.6, 17.8, μg/ml, respectively but not A375.S2 cell line. However, the extracts of T. foenum-graecum and S. ebulus did not exhibit any significant cytotoxic activity on both melanoma cell lines. Conclusion: The results of these experiments show that methanol extracts of licorice, chamomile, sage and rhubarb have significant antiproliferative activity onWM1361A cell line; a representative human melanotic melanocyte tumor cell line. This renders these plants as potential sources of new lead compounds for the development of new drugs for melanoma cancer. Keywords: Melanoma, Plant extract, tyrosinase, Licorice, Chamomile, Sage, Rhubarb, WM1361A

UVA radiation augments cytotoxic activity of psoralens in melanoma cells

Purpose: Melanoma is an aggressive form of skin cancer. The aim of the study was to evaluate the influence of UVA radiation and psoralens: 5-methoxypsoralen (5-MOP) or 8-methoxypsoralen (8-MOP) on melanoma cells viability.Materials and methods: The amelanotic C32 and melanotic COLO829 human melanoma cell lines were exposed to increasing concentrations of psoralens (0.1–100 μM) in the presence or absence of UVA radiation. Cell viability was evaluated by the WST-1 assay.Results: We demonstrated that 8-MOP, in contrast to 5-MOP, has no cytotoxic effect on both melanoma cell lines. Simultaneous exposure of cells to 8-MOP and UVA radiation caused significant cytotoxic response in C32 cells where the EC50 value was estimated to be 131.0 μM (UVA dose: 1.3 J/cm2) and 105.3 μM (UVA dose: 2.6 J/cm2). The cytotoxicity of 5-MOP on both C32 and COLO829 cells was significantly augmented by UVA radiation – the EC50 was estimated to be 22.7 or 7.9 μM (UVA dose: 1.3 J/cm2) and 24.2 or 7.0 μM (UVA dose: 2.6 J/cm2), respectively.Conclusions: The demonstrated high cytotoxic response after simultaneous exposure of melanoma cells to psoralens and UVA radiation in vitro suggests the usefulness of PUVA therapy to treat melanoma in vivo.

Synthesis and characterization of a novel radioiodinated phenylacetamide and its homolog as theranostic agents for malignant melanoma

Melanin is an attractive target for the diagnosis and treatment of malignant melanoma. This study reports the preparation and biological characterizations of N-(2-(diethylamino)ethyl)-2-(3-123/131I-iodo-4-hydroxyphenyl)acetamide and N-(2-(diethylamino)ethyl)-3-(3-123/131I-iodo-4-hydroxyphenyl)propanamide (123/131I-IHPA and 123/131I-IHPP) as novel melanin-specific theranostic agents. These two tracers were hydrophilic, exhibited good serum stability and high binding affinity to melanin. In vitro and in vivo studies revealed rapid, high and tenacious uptakes of both 131I-IHPA and 131I-IHPP in melanotic B16F0 cell line and in C57BL/6 mice bearing B16F0 melanoma, but not in amelanonic A375 cell line and tumors. Small-animal SPECT imaging also clearly delineate B16F0 melanoma since 1h postinjection of 123I-IHPA and 123I-IHPP in tumor-bearing mice. Owing to the favorable biodistribution of 131I-IHPA and 131I-IHPP after intravenous administration, the estimated absorption dose was low in most normal organs and relatively high in melanotic tumor. The melanin-specific binding ability, sustained tumor retention, fast normal tissues clearance and acceptable projected human dosimetry supported that these two tracers are promising theranostic agents for melanin-positive melanoma.

Normal black kidney.

A black kidney has 3 major differential diagnoses: hemosiderosis, lipofuscin pigment and melanotic renal cell carcinoma. Excluding lipofuscin, the other 2 are accompanied by an abnormal renal function. We report on a 25-year-old man who intended to donate a kidney to his cousin. On the operating room table when we incised the left flank region and exposed the kidney, we found a firm and black kidney so the operation was cancelled due to potential vascular injuries. Days after the incomplete procedure, we reviewed the donor's biochemistry and imaging to reassess his renal function, but the results showed quite normal renal function again. The result of Ham test was also negative. Two weeks later, we began the operation, removed the same left kidney and found that it was in the same conditions as it was before. We took the opportunity to send needle biopsies of the kidney for histopathologic analysis. The analysis showed a melanotic kidney without pathological changes in glomeruli and interstitium and vessels. A black kidney may result in hemosiderin, lipofuscin or melanin deposits in the kidney, which can confirm the diagnosis; however, special tests for underlying disease and renal function should be considered. Some causes of black kidney lead to abnormal function, but our patients's kidney returned to normal.

Atg6 is required for multiple vesicle trafficking pathways and hematopoiesis in Drosophila

Atg6 (beclin 1 in mammals) is a core component of the Vps34 complex that is required for autophagy. Beclin 1 (Becn1) functions as a tumor suppressor, and Becn1+/- tumors in mice possess elevated cell stress and p62 levels, altered NF-κB signaling and genome instability. The tumor suppressor function of Becn1 has been attributed to its role in autophagy, and the potential functions of Atg6/Becn1 in other vesicle trafficking pathways for tumor development have not been considered. Here, we generate Atg6 mutant Drosophila and demonstrate that Atg6 is essential for autophagy, endocytosis and protein secretion. By contrast, the core autophagy gene Atg1 is required for autophagy and protein secretion, but it is not required for endocytosis. Unlike null mutants of other core autophagy genes, all Atg6 mutant animals possess blood cell masses. Atg6 mutants have enlarged lymph glands (the hematopoietic organ in Drosophila), possess elevated blood cell numbers, and the formation of melanotic blood cell masses in these mutants is not suppressed by mutations in either p62 or NFκB genes. Thus, like mammals, altered Atg6 function in flies causes hematopoietic abnormalities and lethality, and our data indicate that this is due to defects in multiple membrane trafficking processes.

Atg6 is required for multiple vesicle trafficking pathways and hematopoiesis in Drosophila

Atg6 (beclin 1 in mammals) is a core component of the Vps34 complex that is required for autophagy. Beclin 1 (Becn1) functions as a tumor suppressor, and Becn1(+/-) tumors in mice possess elevated cell stress and p62 levels, altered NF-κB signaling and genome instability. The tumor suppressor function of Becn1 has been attributed to its role in autophagy, and the potential functions of Atg6/Becn1 in other vesicle trafficking pathways for tumor development have not been considered. Here, we generate Atg6 mutant Drosophila and demonstrate that Atg6 is essential for autophagy, endocytosis and protein secretion. By contrast, the core autophagy gene Atg1 is required for autophagy and protein secretion, but it is not required for endocytosis. Unlike null mutants of other core autophagy genes, all Atg6 mutant animals possess blood cell masses. Atg6 mutants have enlarged lymph glands (the hematopoietic organ in Drosophila), possess elevated blood cell numbers, and the formation of melanotic blood cell masses in these mutants is not suppressed by mutations in either p62 or NFκB genes. Thus, like mammals, altered Atg6 function in flies causes hematopoietic abnormalities and lethality, and our data indicate that this is due to defects in multiple membrane trafficking processes.

99mTc(I)/Re(I) tricarbonyl complexes for in vivo targeting of melanotic melanoma: Synthesis and biological evaluation

The 99mTc (I) tricarbonyl complexes fac-[99mTc(κ3-L)(CO)3] (Tc1–Tc6) containing N-ethylpyrrolidine and N,N-diethylethylamine groups for melanin binding, were evaluated in vitro and in vivo as radioactive probes for the targeting of melanotic melanoma. Aiming at the modification of their size, topology and lipophilicity, Tc1–Tc6 were obtained based on an S,N,O-donor bifunctional chelator (BFC) derived from cysteamine and on pyridyl- and pyrazolyl-containing N,N,O-donor BFCs. Tc1–Tc6 were chemically identified by HPLC comparison with the Re congeners (Re1–Re6) that were synthesized at the macroscopic level and fully characterized by common analytical techniques. With the exception of Tc5 and Tc6, these 99mTc complexes are moderately lipophilic, and bind to melanin with moderate to high affinity (23–87%). The cell uptake of Tc1–Tc6, expressed as a percentage of total activity per million cells, spanned between 0.86 and 21.02% for the melanotic B16-F1 cell line and between 0.49% and 13.58% for the amelanotic A375 cell line. In the B16-F1 cell line, Tc1, Tc3 and Tc4 showed moderate cellular uptake values (>10% at 4 h of incubation). In the amelanotic A375 cell line, only Tc4 has shown a moderate cell uptake (>10% at 4 h of incubation), with all the other compounds displaying a relatively poor uptake, i.e. inferior to 5%. Competition studies with haloperidol have shown that the involvement of sigma receptors in cellular uptake and retention is likely to occur for Tc4. Complex Tc1, stabilized with the S,N,O-donor BFC and containing a N,N-diethylethylamine group, presented the most promising biological profile for in vivo targeting of melanoma, showing a moderate tumor uptake of 2.17% ID/g at 1 h p.i in a B16-F1 melanoma-bearing mouse and rather favorable target/non-target ratios with values as high as 16.9 and 5.2 for tumor/muscle and tumor/blood ratios, respectively.

Multiple plexiform schwannoma of a finger

ejd.2011.1609 Auteur(s) : Jiong Zhou, Xiao-Yong Man, Min Zheng, Sui-Qing Cai cai.suiqing@gmail.com Department of Dermatology, Second Affiliated Hospital, Hangzhou 310009, China Schwannomas are benign neurogenic tumors, first described by Verocay in 1908 [1]. There are 7 subtypes: classical (Verocay), cranial nerve, cellular, plexiform, degenerated (ancient), melanotic, and granular cell schwannoma [2]. Plexiform schwannoma is a rare subtype, accounting for approximately 5% of schwannomas [2]. Sometimes, [...]

Accumulation of 2‐Thiouracils by Melanotic Melanocytes

With the aid of a specific GC-MS method utilizing negative ion-chemical ionization, the extracellular and intracellular concentrations of the free 2-thiouracils, 2-thiouracil and 6-propyl-2-thiouracil were measured after their incubation with melanotic and amelanotic melanocytes. Only with the melanotic cell preparation exposed to low concentrations of thiouracil (40 ng/106 cells) was there a reduction of the thiouracil concentration. When the extracellular 2-thiouracil concentration was increased a thousandfold (40 μg/106 cells), appreciable accumulation by the melanotic melanocytes was observed only with the more lipophilic 2-thiouracil, propylthiouracil, which also paralleled its greater toxicity compared with thiouracil. Both these observations suggest increased propylthiouracil cell penetration compared with thiouracil due to its greater lipophilicity.

Inhibition of basal and ultraviolet B-induced melanogenesis by cannabinoid CB1 receptors: a keratinocyte-dependent effect

Ultraviolet radiation is the major environmental insult to the skin and stimulates the synthesis of melanin in melanocytes, which then distribute it to the neighboring keratinocytes where it confers photo-protection. Skin color results from the paracrine interaction between these two cell types. Recent studies suggest that endocannabinoids are potential mediators in the skin. Here, we investigated whether cannabinoid drugs play a role in melanogenesis and if ultraviolet radiation modifies the cutaneous endocannabinoid system. We used human melanotic melanoma cell line (SK-mel-1) in monoculture or co-culture with human keratinocytes (HaCat). Endocannabinoid levels, cannabinoid receptors expression, and melanin content were evaluated under basal conditions and after ultraviolet-B irradiation (311 nm). We provide evidence that human melanoma cells (SK-mel-1) express CB(1) receptors, and when in co-culture with keratinocytes (HaCat), the selective CB(1) receptor agonist arachidonyl-2-chloroethylamide (ACEA 1 and 10 μM) inhibited (by 33.4 and 37.3%, respectively) basal melanogenesis. In addition, ultraviolet-B-induced melanogenesis in co-cultures was abolished by ACEA 10 μM. Both ACEA inhibitory effects were reversed by AM251 (1 μM), a selective CB(1) antagonist. Furthermore, ultraviolet-B radiation increased endocannabinoids levels only in keratinocytes, whereas CB(1) cannabinoid receptor expression was up-regulated only in melanoma cells. Our results collectively suggest that ultraviolet radiation activates paracrine CB(1)-mediated endocannabinoid signaling to negatively regulate melanin synthesis. The endocannabinoid system in the skin may be a possible target for future therapies in pigmentary disorders.