Lithium salts cytotoxicity and accumulation in melanoma cells in vitro

Boron neutron capture therapy is a perspective selective technology for the destruction of cancer cells, while the use of lithium instead of boron may represent a new and promising vector for the development of neutron capture therapy (NCT). The aim of the study was a comparative assessment of the cytotoxicity of various lithium salts, as well as an analysis of the accumulation of lithium in tumor cells in vitro to determine the possibility of using lithium in NCT. The cytotoxicity of lithium salts was determined using MTT-test and colony forming assay on human fibroblasts BJ-5ta, human skin melanoma SK-Mel-28, and mouse skin melanoma B16 cell lines. An assessment of lithium concentration in cells was performed using inductively coupled plasma atomic emission spectrometry. Our results showed that three different lithium salts at a concentration of 40 μg/ml are not toxic for both tumor and normal cells. The highest uptake values were obtained on murine melanoma B16 cells when exposed to lithium carbonate (0.8 μg/106 cells); however, human melanoma SK-Mel-28 cells effectively accumulated both lithium carbonate and lithium citrate (about 0.46 μg/106 cells for two salts). Thus, our results demonstrate a range of non-toxic doses of lithium salts and a high uptake of lithium by tumor cells, which indicates the possibility to use the lithium in NCT.

Optimizing time prediction and error classification in early melanoma detection using a hybrid RCNN-LSTM model

Skin cancer is a terrifying disorder that affects all individuals. Due to the significant increase in the rate of melanoma skin cancer, early detection of skin cancer is now more critical than ever before. Malignant melanoma is one of the most serious forms of skin cancer, and it is caused by abnormal melanocyte cell growth. In recent years, skin cancer predictive categorization has become more accurate and predictive due to multiple deep learning algorithms. Malignant melanoma is diagnosed using the Recurrent Convolution Neural Network-Long Short-Term Memory (RCNN-LSTM), which is one of the deep learning classification approaches. Using the International Skin Image Collection and the RCNN-LSTM, the data are categorized and analyzed to gain a better understanding of skin cancer. The method begins with data preprocessing, which prepares the dataset for classification. Additionally, the RCNN is employed to extract the features that are vital to the prediction process. The LSTM is accountable for the final step, classification. There are further factors to examine, such as the precision of 94.60%, the sensitivity of 95.67%, and the F1-score of 95.13%. Other benefits of the suggested study include shorter prediction durations of 95.314, 122.530, and 131.205 s and lower model loss of 0.25%, 0.19%, and 0.15% for input sizes 10, 15, and 20, respectively. Three datasets had a reduced categorization error of 5.11% and an accuracy of 95.42%. In comparison to previous approaches, the work discussed here produces superior outcomes. RESEARCH HIGHLIGHTS: Recurrent convolutional neural network (RCNN) deep learning approach for optimizing time prediction and error classification in early melanoma detection. It extracts a high number of specific features from the skin disease image, making the classification process easier and more accurate. To reduce classification errors in accurately detecting melanoma, context dependency is considered in this work. By accounting for context dependency, the deprivation state is avoided, preventing performance degradation in the model. To minimize melanoma detection model loss, a skin disease image augmentation or regularization process is performed in this work. This strategy improves the accuracy of the model when applied to fresh, previously unobserved data.

Assessment of Autophagy in Tumor Cells of Human Skin Melanoma of Different Stages

High levels of autophagy can increase the viability of tumor cells as well as their resistance to chemotherapy. Evaluation of the dynamics of autophagy processes at different stages of carcinogenesis can extend our understanding of melanoma pathogenesis to develop new therapeutic approaches. We performed a comparative study of tumor cell autophagy in stages II and III human skin melanoma. Tumor cells were characterized by high content of structures associated with autophagy (autophagosomes and autolysosomes). In stage III melanoma characterized by the presence of regional metastases in the lymph nodes, tumor cells showed higher expression of the autophagy marker protein LC3beta in comparison with stage II melanoma cells, which can indicate the involvement of autophagy processes in tumor progression and the formation of metastases in the lymph nodes.

LncRNA LINC00847 accelerates melanoma progression by regulating miR-133a-3p/TGFBR1 axis

AIMS

Growing evidence has suggested that lncRNAs play a regulatory role in tumorigenesis. Dysregulation of a newly identified lncRNA (LINC00847) has been involved in several tumors. Nevertheless, the expression and roles of lncRNAs in skin melanoma remain unclear. Therefore, we attempted to investigate the expressions and roles of lncRNAs in this study.

MATERIALS AND METHODS

Expression levels of LINC00847 were quantified in tissue samples from the TCGA database and clinically recruited participants. LINC00847 was inhibited in cells by transfecting with si-LINC00847 or si-NC. Expressions of LINC00847 and miR-133a-3p were determined using RT-qPCR, and the TGFBR1 level was determined using Western blotting. Targeting sites of LINC00847 with miR-133a-3p and miR-133a-3p with TGFBR1 were predicted by bioinformatic tools and proved by dual-luciferase reporter system and RNA immunoprecipitation. Cell proliferation, invasion, and migration abilities were assessed using CCK8, cell colony formation, cell wound scratch, and transwell assay, respectively.

RESULTS

In both TCGA and clinical cohorts, the expression of LINC00847 was abnormally upregulated in skin melanoma tissues than that of benign nevus. Besides, LINC00847 expression increased more markedly in A375 and SK-MEL-28 cells than in normal epidermal melanocytes (HEMa-LP cells). LINC00847 knockdown remarkably restrained skin melanoma cell proliferation, metastasis, and wound healing rate. Furthermore, miR-133a-3p/TGFBR1 was the downstream target for LINC00847. LINC00847 negatively regulated miR-133a-3p expression in skin melanoma cells. Both miR-133a-3p inhibitors and TGFBR1 vector transfection reversed the effect of LINC00847 silence in skin melanoma cells.

CONCLUSION

LINC00847 was highly expressed in skin melanoma, and its overexpression accelerated the malignant tumor behavior of skin melanoma cells. The miR-133a-3p /TGFBR1 axis was involved in the roles of LINC00847 in skin melanoma.

Histopathologic and Molecular Features of Cutaneous Melanoma in a Moroccan Population

Background Cutaneous cancer is the most common malignancy type, among which melanomas are considered the most aggressive and lethal. In Morocco, skin melanoma is the 25th most common cancer. To our knowledge, this is the first and largest Moroccan study specifically describing cutaneous melanoma.  Materials and methods We obtained data for 100 patients diagnosed with cutaneous melanoma in the Department of Pathology of Hassan II University Hospital, Morocco. Clinical, histopathological, molecular, and follow-up data were recorded from pathology request forms and the patient's medical records.  Results The mean age of our patients was 65 years old. Histologically, the most prevalent were the nodular (48%) and acro-lentiginous (38%) melanoma subtypes. A total of 66% of the patients had a Breslow thickness of >4 mm. The presence of ulceration was noted in 46% of cases. The average mitoses was 9/1 mm². A total of 44% of patients had metastatic melanoma at the time of diagnosis. The BRAF V600E mutation was found in six cases, and the C-KIT mutation in five cases. The five-year overall survival and metastasis-free survival were 85% and 15%, respectively. There was a significant correlation between Breslow thickness and Clark's level (p<0.001), histologic subtype (p=0.012), and presence of metastasis (p=0.002). There was a significant difference between the head and neck melanomas and those of the feet, particularly in the histological subtype and the presence of ulceration. BRAF V600E mutation was found in six cases of metastatic melanomas of the head and neck, of which three cases were positive for this mutation, as compared with the 23 cases of acral melanomas, which tested negative for the same mutation.  Conclusion The results of our study showed that cutaneous melanomas were characterized by advanced age at diagnosis and late-stage diagnosis with a high Breslow index. The lower limbs were the most affected sites, especially in the plantar region. The acral lentiginous subtype was the most common. The presence of BRAF V600E mutation was associated with a better prognosis.

Study of Lithium Biodistribution and Nephrotoxicity in Skin Melanoma Mice Model: The First Step towards Implementing Lithium Neutron Capture Therapy

Boron neutron capture therapy (BNCT) is one of the promising treatment methods for malignant melanoma. The main issue of this technology is the insufficient selectivity of ¹⁰B accumulation in tumor cells. As a result of the neutron absorption by boron, an 84% energy release occurred within the cell by the nuclear reaction ¹⁰B (n, α)⁷Li, which lead to tumor cell death. The use of lithium instead of boron brings a new unique opportunity-local 100% energy release-since all products of the ⁶Li (n, α)³H reaction have high linear energy transfer characteristics. The aim of this study was to determine the concentrations of Li in the tumor, skin, blood, brain and kidney in experimental animals with B16 melanoma and to analyze the potential Li toxicity after lithium carbonate administration at single doses of 300 and 400 mg/kg. Lithium carbonate was chosen since there is a long-term experience of its use in clinical practice for the treatment of psychiatric disorders. The inductively coupled plasma atomic emission spectrometry was used to evaluate Li concentrations in tissue samples. The accumulation efficiency of Li in the tumor was the highest at a time point of 30 min (22.4 µg/g; at a dose of 400 mg/kg). Despite the high lithium accumulation in the kidneys, the pathological changes in kidney tissues were not found. Thus, lithium may actually be used for the Li-NCT development and future studies can be conducted using ⁶Li and following irradiation of tumor cells using the schemes of lithium administration tested in this work.

Mortality Trends Due to Skin Melanoma in Poland in the Years 2000-2020

The aim of this article is to assess mortality trends due to skin melanoma in Poland between the years 2000 and 2020, taking into account gender and place of residence (urban, rural). The subject of the analyses was data on 25,061 deaths that occurred between 2000 and 2020 due to skin melanoma (C43 according to ICD-10). Mortality rates due to this cancer, both crude (CDR) and standardised (SDR), were calculated. Trends on the calculated rates were analysed using the annual percentage change (APC) and average annual percentage change (AAPC), obtained from joinpoint regression models. Over the study period, the standardised death rate (SDR) due to skin melanoma in Poland increased from 3.60 to 4.03 per 100,000 population (AAPC = 1.1; p < 0.05), for urban residents it increased from 3.56 to 3.91 (APC = 1.2; p < 0.05) and for rural residents it increased from 3.00 to 4.24 (APC = 2.2; p < 0.05). A higher growth rate in terms of the SDR value between the years 2000 and 2020 was recorded in men compared to women and in rural when compared to urban residents. In Poland, mortality due to skin melanoma is on the rise. The early diagnosis of this cancer should become common practice in the Polish population.

Genomic landscape of the immunogenicity regulation in skin melanomas with diverse tumor mutation burden

Skin melanoma cells are tightly interconnected with their tumor microenvironment (TME), which influences their initiation, progression, and sensitivity/resistance to therapeutic interventions. An immune-active TME favors patient response to immune checkpoint inhibition (ICI), but not all patients respond to therapy. Here, we assessed differential gene expression in primary and metastatic tumors from the TCGA-SKCM dataset, compared to normal skin samples from the GTEx project and validated key findings across 4 independent GEO datasets, as well as using immunohistochemistry in independent patient cohorts. We focused our attention on examining the expression of various immune receptors, immune-cell fractions, immune-related signatures and mutational signatures across cutaneous melanomas with diverse tumor mutation burdens (TMB). Globally, the expression of most immunoreceptors correlated with patient survival, but did not differ between TMBhigh and TMBlow tumors. Melanomas were enriched in "naive T-cell", "effector memory T-cell", "exhausted T-cell", "resting Treg T-cell" and "Th1-like" signatures, irrespective of their BRAF, NF1 or RAS mutational status. Somatic mutations in IDO1 and HLA-DRA were frequent and could be involved in hindering patient response to ICI therapies. We finally analyzed transcriptome profiles of ICI-treated patients and associated their response with high levels of IFNγ, Merck18, CD274, CD8, and low levels of myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs) and M2 macrophages, irrespective of their TMB status. Overall, our findings highlight the importance of pre-existing T-cell immunity in ICI therapeutic outcomes in skin melanoma and suggest that TMBlow patients could also benefit from such therapies.

Case volume regionalization and volume-based outcome differences in cutaneous head and neck melanoma

BACKGROUND

Hospital volume has emerged as a prognostic factor in oncology but is not currently known whether volume is associated with improved outcomes for cutaneous head and neck (HN) melanoma.

METHODS

A total of 556 079 cutaneous melanoma cases reported by the 2004-2016 National Cancer Database were separated into two cohorts (HN and non-HN) and facilities within each cohort were classified by case volume. Analysis employed chi-square, analysis of variance, Kaplan-Meier, and Cox proportional hazards models.

RESULTS

Only 41 facilities (3.1% of 1326) treating HN melanoma and 50 facilities (3.7% of 1344) treating non-HN melanoma were classified as high-volume facilities (HVFs). The estimated 5-year overall survival (OS) was 62.7% (standard error [SE]: 0.4%) for patients with HN at low-volume facilities (LVFs), 69.3% (SE: 0.4%) at IVFs, and 71.8% (SE 0.4%) at HVFs (p < 0.001). Differences in OS remained significant between HVFs versus LVFs after adjusting for confounders.

CONCLUSION

Volume is independently associated with OS and improved surgical outcomes for HN melanoma.

Cutaneous Melanomas: A Single Center Experience on the Usage of Immunohistochemistry Applied for the Diagnosis

Cutaneous melanoma (cM) is the deadliest of all primary skin cancers. Its prognosis is strongly influenced by the stage at diagnosis, with early stages having a good prognosis and being potentially treatable with surgery alone; advanced stages display a much worse prognosis, with a high rate of recurrence and metastasis. For this reason, the accurate and early diagnosis of cM is crucial-misdiagnosis may have extremely dangerous consequences for the patient and drastically reduce their chances of survival. Although the histological exam remains the "gold standard" for the diagnosis of cM, a continuously increasing number of immunohistochemical markers that could help in diagnosis, prognostic characterization, and appropriate therapeutical choices are identified every day, with some of them becoming part of routine practice. This review aims to discuss and summarize all the data related to the immunohistochemical analyses that are potentially useful for the diagnosis of cM, thus rendering it easier to appropriately applicate to routine practice. We will discuss these topics, as well as the role of these molecules in the biology of cM and potential impact on diagnosis and treatment, integrating the literature data with the experience of our surgical pathology department.

Lithium Enhances Autophagy and Cell Death in Skin Melanoma: An Ultrastructural and Immunohistochemical Study

Lithium is an inhibitor of glycogen synthase kinase 3 beta, which is traditionally used in the treatment of bipolar disorders and has antitumor effects. The aim of the current study was to determine if lithium salt causes autophagy and apoptosis in skin melanoma cells to enhance cell death. Light microscopy, transmission electron microscopy, immunohistochemistry, and immunofluorescence were used to study the mechanism of action of lithium carbonate in B16 melanoma cells in vivo. Proliferating cell nuclear antigen immunofluorescence assay revealed that the proliferation of B16 melanoma cells was suppressed by lithium treatment for 7 days. Electron microscopy demonstrated a significant increase in the number of autophagic vacuoles in lithium-treated cells relative to control. In addition, levels of autophagy markers LC3 beta and LAMP1 found in lithium-treated tumor xenografts were higher than levels of these markers in the control tumors. Lithium induced caspase-3 expression and apoptotic cell death in tumor cells. Thus, lithium carbonate is the compound that inhibits cell proliferation and stimulates cell death in melanoma cells through induction of autophagy and apoptosis. Stimulation of autophagy by lithium could contribute to the development of autophagic cell death in tumor cells.

Molecular Pathology of Skin Melanoma: Epidemiology, Differential Diagnostics, Prognosis and Therapy Prediction

Similar to other malignancies, TCGA network efforts identified the detailed genomic picture of skin melanoma, laying down the basis of molecular classification. On the other hand, genome-wide association studies discovered the genetic background of the hereditary melanomas and the susceptibility genes. These genetic studies helped to fine-tune the differential diagnostics of malignant melanocytic lesions, using either FISH tests or the myPath gene expression signature. Although the original genomic studies on skin melanoma were mostly based on primary tumors, data started to accumulate on the genetic diversity of the progressing disease. The prognostication of skin melanoma is still based on staging but can be completed with gene expression analysis (DecisionDx). Meanwhile, this genetic knowledge base of skin melanoma did not turn to the expected wide array of target therapies, except the BRAF inhibitors. The major breakthrough of melanoma therapy was the introduction of immune checkpoint inhibitors, which showed outstanding efficacy in skin melanoma, probably due to their high immunogenicity. Unfortunately, beyond BRAF, KIT mutations and tumor mutation burden, no clinically validated predictive markers exist in melanoma, although several promising biomarkers have been described, such as the expression of immune-related genes or mutations in the IFN-signaling pathway. After the initial success of either target or immunotherapies, sooner or later, relapses occur in the majority of patients, due to various induced genetic alterations, the diagnosis of which could be developed to novel predictive genetic markers.

Aetiology and Pathogenesis of Cutaneous Melanoma: Current Concepts and Advances

Melanoma develops from malignant transformations of the pigment-producing melanocytes. If located in the basal layer of the skin epidermis, melanoma is referred to as cutaneous, which is more frequent. However, as melanocytes are be found in the eyes, ears, gastrointestinal tract, genitalia, urinary system, and meninges, cases of mucosal melanoma or other types (e.g., ocular) may occur. The incidence and morbidity of cutaneous melanoma (cM) are constantly increasing worldwide. Australia and New Zealand are world leaders in this regard with a morbidity rate of 54/100,000 and a mortality rate of 5.6/100,000 for 2015. The aim of this review is to consolidate and present the data related to the aetiology and pathogenesis of cutaneous melanoma, thus rendering them easier to understand. In this article we will discuss these problems and the possible impacts on treatment for this disease.

Identification of prognostic genes and construction of a novel gene signature in the skin melanoma based on the tumor microenvironment

Skin melanoma remains a highly prevalent and yet deadly form of cancer, with the exact degree of melanoma-associated mortality being strongly dependent upon the local tumor microenvironment. The exact composition of stromal and immune cells within this microenvironmental region has the potential to profoundly impact melanoma progression and prognosis. As such, the present study was designed with the goal of clarifying the predictive relevance of stromal and immune cell-related genes in melanoma patients through comprehensive bioinformatics analyses. We therefore analyzed melanoma sample gene expression within The Cancer Genome Atlas database and employed the ESTIMATE algorithm as a means of calculating both stromal and immune scores that were in turn used for identifying differentially expressed genes (DEGs). Subsequently, univariate analyses were used to detect DEGs associated with melanoma patient survival, and through additional functional enrichment analyses, we determined that these survival-related DEGs are largely related to inflammatory and immune responses. A prognostic signature comprised of 10 genes (IL15, CCL8, CLIC2, SAMD9L, TLR2, HLA.DQB1, IGHV1-18, RARRES3, GBP4, APOBEC3G) was generated. This 10-gene signature effectively separated melanoma patients into low- and high-risk groups based upon their survival. These low- and high-risk groups also exhibited distinct immune statuses and differing degrees of immune cell infiltration. In conclusion, our results offer novel insights into a number of microenvironment-associated genes that impact survival outcomes in melanoma patients, potentially highlighting these genes as viable therapeutic targets.

Ultrasound-Mediated Microbubble Destruction Inhibits Skin Melanoma Growth by Affecting YAP1 Translation Using Ribosome Imprinting Sequencing

Cutaneous melanoma (CMM) is a skin tumor with a high degree of malignancy. BRAF resistance imposes great difficulty to the treatment of CMM, and partially contributes to the poor prognosis of CMM. YAP is involved in the growth and drug resistance of a variety of tumors, and mechanical signals may affect the activation of YAP1. As a novel ultrasound treatment technology, ultrasound-mediated microbubble destruction (UMMD) has been reported to have a killing effect on isolated CMM cells. In this study, the tumor tissue samples were collected from 64 CMM patients. We found that YAP1 mRNA expression was irrelevant to the clinicopathological characteristics and prognostic survival of the CMM patients. The drug-resistant cell line was constructed and subcutaneously implanted into nude mice, which were further separately treated with UMMD, ultrasound (US), and microbubbles (MB). The result showed that UMMD significantly inhibited the growth of tumor tissues. Ribosome imprinting sequencing (Ribo-seq) is a genetic technology for studying protein translation at genetic level. Ribo-seq, RNA-seq, and RT-qPCR were applied to detect YAP1 expression in CMM mouse tumor tissues. Ribo-seq data revealed that UMMD greatly up-regulated the expression of YAP1, interestingly, the up-regulated YAP1 was found to be negatively correlated with the weight of tumor tissues, while no significant change in YAP1 expression was detected by RNA-seq or RT-qPCR assay. These results indicated that UMMD could inhibit the tumor growth of drug-resistant CMM by affecting the translation efficiency of YAP1, providing a strong basis for the clinical treatment of UMMD in CMM.

Computer vision for microscopic skin cancer diagnosis using handcrafted and non-handcrafted features

Skin covers the entire body and is the largest organ. Skin cancer is one of the most dreadful cancers that is primarily triggered by sensitivity to ultraviolet rays from the sun. However, the riskiest is melanoma, although it starts in a few different ways. The patient is extremely unaware of recognizing skin malignant growth at the initial stage. Literature is evident that various handcrafted and automatic deep learning features are employed to diagnose skin cancer using the traditional machine and deep learning techniques. The current research presents a comparison of skin cancer diagnosis techniques using handcrafted and non-handcrafted features. Additionally, clinical features such as Menzies method, seven-point detection, asymmetry, border color and diameter, visual textures (GRC), local binary patterns, Gabor filters, random fields of Markov, fractal dimension, and an oriental histography are also explored in the process of skin cancer detection. Several parameters, such as jacquard index, accuracy, dice efficiency, preciseness, sensitivity, and specificity, are compared on benchmark data sets to assess reported techniques. Finally, publicly available skin cancer data sets are described and the remaining issues are highlighted.

Skin melanoma survival is not superior in females in the new stage IIID of the 8th edition of the staging system: an analysis of data from the Surveillance, Epidemiology, and End Results (SEER) database

Background

In the 8th edition of the melanoma staging system, stage III was divided into stages IIIA-IIID. Previous studies have found that the long-term survival rate of females is much higher than that of males. This study was designed to explore whether this sex-specific advantage still exists in the new staging subgroups.

Methods

We obtained data from individuals diagnosed with skin melanoma between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. A total of 8,726 patients with stage III disease were enrolled in the study (5,370 males and 3,356 females). Among these patients, 505 had stage IIID disease (370 males and 135 females).

Results

In the 7th edition of the staging system, there were significant sex-specific differences in overall survival (OS) and melanoma-specific survival (MSS) in each subgroup of stage III. In stages IIIA-IIIC in the 8th edition, there were also significant differences between males and females (P<0.001), but in stage IIID patients, there were no significant differences in either OS (P=0.312) or MSS (P=0.288). Cox analysis confirmed that stage IIID does not affect prognosis in males. Further research found no difference between males and females with stage IIID disease in any age subgroup.

Conclusions

We compared sex-specific survival differences in patients with stage III disease according to the 8th edition of the staging system. Females with stage IIIA-IIIC disease have better survival rates than males. However, among patients with stage IIID disease, there is no significant difference in survival between males and females.

Immune Microenvironment Related Competitive Endogenous RNA Network as Powerful Predictors for Melanoma Prognosis Based on WGCNA Analysis

Cutaneous melanoma is the most life-threatening skin malignant tumor due to its increasing metastasis and mortality rate. The abnormal competitive endogenous RNA network promotes the development of tumors and becomes biomarkers for the prognosis of various tumors. At the same time, the tumor immune microenvironment (TIME) is of great significance for tumor outcome and prognosis. From the perspective of TIME and ceRNA network, this study aims to explain the prognostic factors of cutaneous melanoma systematically and find novel and powerful biomarkers for target therapies. We obtained the transcriptome data of cutaneous melanoma from The Cancer Genome Atlas (TCGA) database, 3 survival-related mRNAs co-expression modules and 2 survival-related lncRNAs co-expression modules were identified through weighted gene co-expression network analysis (WCGNA), and 144 prognostic miRNAs were screened out by univariate Cox proportional hazard regression. Cox regression model and Kaplan-Meier survival analysis were employed to identify 4 hub prognostic mRNAs, and the prognostic ceRNA network consisting of 7 lncRNAs, 1 miRNA and 4 mRNAs was established. After analyzing the composition and proportion of total immune cells in cutaneous melanoma microenvironment through CIBERSORT algorithm, it is found through correlation analysis that lncRNA-TUG1 in the ceRNA network was closely related to the TIME. In this study, we first established cutaneous melanoma’s TIME-related ceRNA network by WGCNA. Cutaneous melanoma prognostic markers have been identified from multiple levels, which has important guiding significance for clinical diagnosis, treatment, and further scientific research on cutaneous melanoma.

Characterization of Melanin Radicals in Paraffin-embedded Malignant Melanoma and Nevus Pigmentosus Using X-band EPR and EPR Imaging

Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens. The EPR results revealed that the peak-to-peak linewidths (ΔH_pp) of paraffin-embedded MM and NP samples were 0.65 ± 0.01 and 0.69 ± 0.01 mT, respectively. The g-value was 2.005 for both samples. Moreover, the two-dimensional (2D) EPRI of the MM showed different signal intensities at the different tumor stages, unlike the NP, which displayed fewer variations in signal intensity. Thus, the present results suggest that EPR and 2D EPRI can be useful for characterization of the two melanin radicals in the MM and for determination of their size and concentration.

CYP24A1 expression inversely correlates with melanoma progression: clinic-pathological studies

The major role of 24-hydroxylase (CYP24A1) is to maintain 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) homeostasis. Recently, it has been discovered that CYP24A1 also catalyses the hydroxylation of 20(OH)D3, producing dihydroxy-derivatives that show very effective antitumorigenic activities. Previously we showed a negative correlation of vitamin D receptor (VDR) and CYP27B1 expression with progression, aggressiveness and overall or disease-free survivals of skin melanomas. Therefore, we analyzed CYP24A1 expression in relation to clinicopathomorphological features of nevi, skin melanomas and metastases. In melanocytic tumors, the level of CYP24A1 was higher than in the normal epidermis. The statistically highest mean CYP24A1 level was found in nevi and early stage melanomas. With melanoma progression, CYP24A1 levels decreased and in advanced stages were comparable to the normal epidermis and metastases. Furthermore, the CYP24A1 expression positively correlated with VDR and CYP27B1, and negatively correlated with mitotic activity. Lower CYP24A1 levels correlated with the presence of ulceration, necrosis, nodular type and amelanotic phenotypes. Moreover, a lack of detectable CYP24A1 expression was related to shorter overall and disease-free survival. In conclusion, the local vitamin D endocrine system affects melanoma behavior and an elevated level of CYP24A1 appears to have an important impact on the formation of melanocytic nevi and melanomagenesis, or progression, at early stages of tumor development.