Lipid fingerprint-based histology accurately classifies nevus, primary melanoma, and metastatic melanoma samples.

Probably, the most important factor for the survival of a melanoma patient is early detection and precise diagnosis. Although in most cases these tasks are readily carried out by pathologists and dermatologists, there are still difficult cases in which no consensus among experts is achieved. To deal with such cases, new methodologies are required. Following this motivation, we explore here the use of lipid imaging mass spectrometry as a complementary tool for the aid in the diagnosis. Thus, 53 samples (15 nevus, 24 primary melanomas, and 14 metastasis) were explored with the aid of a mass spectrometer, using negative polarity. The rich lipid fingerprint obtained from the samples allowed us to set up an artificial intelligence-based classification model that achieved 100% of specificity and precision both in training and validation data sets. A deeper analysis of the image data shows that the technique reports important information on the tumor microenvironment that may give invaluable insights in the prognosis of the lesion, with the correct interpretation.

Pirin is a prognostic marker of human melanoma that dampens the proliferation of malignant cells by downregulating JARID1B/KDM5B expression.

Originally considered to act as a transcriptional co-factor, Pirin has recently been reported to play a role in tumorigenesis and the malignant progression of many tumors. Here, we have analyzed the diagnostic and prognostic value of Pirin expression in the early stages of melanoma, and its role in the biology of melanocytic cells. Pirin expression was analyzed in a total of 314 melanoma biopsies, correlating this feature with the patient's clinical course. Moreover, PIR downregulated primary melanocytes were analyzed by RNA sequencing, and the data obtained were validated in human melanoma cell lines overexpressing PIR by functional assays. The immunohistochemistry multivariate analysis revealed that early melanomas with stronger Pirin expression were more than twice as likely to develop metastases during the follow-up. Transcriptome analysis of PIR downregulated melanocytes showed a dampening of genes involved in the G1/S transition, cell proliferation, and cell migration. In addition, an in silico approach predicted that JARID1B as a potential transcriptional regulator that lies between PIR and its downstream modulated genes, which was corroborated by co-transfection experiments and functional analysis. Together, the data obtained indicated that Pirin could be a useful marker for the metastatic progression of melanoma and that it participates in the proliferation of melanoma cells by regulating the slow-cycling JARID1B gene.

Melanoma and Nevi Subtype Histopathological Characterization with Optical Coherence Tomography.

BACKGROUND: Melanoma incidence has continued to rise in the latest decades, and the forecast is not optimistic. Non-invasive diagnostic imaging techniques such as optical coherence tomography (OCT) are largely studied; however, there is still no agreement on its use for the diagnosis of melanoma. For dermatologists, the differentiation of non-invasive (junctional nevus, compound nevus, intradermal nevus, and melanoma in-situ) versus invasive (superficial spreading melanoma and nodular melanoma) lesions is the key issue in their daily routine. METHODS: This work performs a comparative analysis of OCT images using haematoxylin-eosin (HE) and anatomopathological features identified by a pathologist. Then, optical and textural properties are extracted from OCT images with the aim to identify subtle features that could potentially maximize the usefulness of the imaging technique in the identification of the lesion's potential invasiveness. RESULTS: Preliminary features reveal differences discriminating melanoma in-situ from superficial spreading melanoma and also between melanoma and nevus subtypes that pose a promising baseline for further research. CONCLUSIONS: Answering the final goal of diagnosing non-invasive versus invasive lesions with OCT does not seem feasible in the short term, but the obtained results demonstrate a step forward to achieve this.

Association of TYR SNP rs1042602 with Melanoma Risk and Prognosis.

Cutaneous melanoma is the most aggressive of skin tumors. In order to discover new biomarkers that could help us improve prognostic prediction in melanoma patients, we have searched for germline DNA variants associated with melanoma progression. Thus, after exome sequencing of a set of melanoma patients and healthy control individuals, we identified rs1042602, an SNP within TYR, as a good candidate. After genotyping rs1042602 in 1025 patients and 773 healthy donors, we found that the rs1042602-A allele was significantly associated with susceptibility to melanoma (CATT test: p = 0.0035). Interestingly, we also observed significant differences between patients with good and bad prognosis (5 years of follow-up) (n = 664) (CATT test for all samples p = 0.0384 and for men alone p = 0.0054). Disease-free-survival (DFS) analyses also showed that patients with the A allele had shorter DFS periods. In men, the association remained significant even in a multivariate Cox Proportional-hazards model, which was adjusted for age at diagnosis, Breslow thickness, ulceration and melanoma subtype (HR 0.4; 95% confidence interval (CI) 0.20-0.83; p = 0.0139). Based on our results, we propose that rs1042602-A is a risk allele for melanoma, which also seems to be responsible for a poorer prognosis of the disease, particularly in men.

RKIP Regulates Differentiation-Related Features in Melanocytic Cells.

Raf Kinase Inhibitor Protein (RKIP) has been extensively reported as an inhibitor of key signaling pathways involved in the aggressive tumor phenotype and shows decreased expression in several types of cancers. However, little is known about RKIP in melanoma or regarding its function in normal cells. We examined the role of RKIP in both primary melanocytes and malignant melanoma cells and evaluated its diagnostic and prognostic value. IHC analysis revealed a significantly higher expression of RKIP in nevi compared with early-stage (stage I-II, AJCC 8th) melanoma biopsies. Proliferation, wound healing, and collagen-coated transwell assays uncovered the implication of RKIP on the motility but not on the proliferative capacity of melanoma cells as RKIP protein levels were inversely correlated with the migration capacity of both primary and metastatic melanoma cells but did not alter other parameters. As shown by RNA sequencing, endogenous RKIP knockdown in primary melanocytes triggered the deregulation of cellular differentiation-related processes, including genes (i.e., ZEB1, THY-1) closely related to the EMT. Interestingly, NANOG was identified as a putative transcriptional regulator of many of the deregulated genes, and RKIP was able to decrease the activation of the NANOG promoter. As a whole, our data support the utility of RKIP as a diagnostic marker for early-stage melanomas. In addition, these findings indicate its participation in the maintenance of a differentiated state of melanocytic cells by modulating genes intimately linked to the cellular motility and explain the progressive decrease of RKIP often described in tumors.

Vitronectin and dermcidin serum levels predict the metastatic progression of AJCC I-II early-stage melanoma.

Like many cancers, an early diagnosis of melanoma is fundamental to ensure a good prognosis, although an important proportion of stage I-II patients may still develop metastasis during follow-up. The aim of this work was to discover serum biomarkers in patients diagnosed with primary melanoma that identify those at a high risk of developing metastasis during the follow-up period. Proteomic and mass spectrophotometry analysis was performed on serum obtained from patients who developed metastasis during the first years after surgery for primary tumors and compared with that from patients who remained disease-free for more than 10 years after surgery. Five proteins were selected for validation as prognostic factors in 348 melanoma patients and 100 controls by ELISA: serum amyloid A and clusterin; immune system proteins; the cell adhesion molecules plakoglobin and vitronectin and the antimicrobial protein dermcidin. Compared to healthy controls, melanoma patients have high serum levels of these proteins at the moment of melanoma diagnosis, although the specific values were not related to the histopathological stage of the tumors. However, an analysis based on classification together with multivariate statistics showed that tumor stage, vitronectin and dermcidin levels were associated with the metastatic progression of patients with early-stage melanoma. Although melanoma patients have increased serum dermcidin levels, the REPTree classifier showed that levels of dermcidin <2.98 µg/ml predict metastasis in AJCC stage II patients. These data suggest that vitronectin and dermcidin are potent biomarkers of prognosis, which may help to improve the personalized medical care of melanoma patients and their survival.

Terfenadine induces apoptosis and autophagy in melanoma cells through ROS-dependent and -independent mechanisms.

Previously we found that terfenadine, an H1 histamine receptor antagonist, acts as a potent apoptosis inducer in melanoma cells through modulation of Ca(2+) homeostasis. In this report, focusing our attention on the apoptotic mechanisms activated by terfenadine, we show that this drug can potentially activate distinct intrinsic signaling pathways depending on culture conditions. Serum-deprived conditions enhance the cytotoxic effect of terfenadine and caspase-4 and -2 are activated upstream of caspase-9. Moreover, although we found an increase in ROS levels, the apoptosis was ROS independent. Conversely, terfenadine treatment in complete medium induced ROS-dependent apoptosis. Caspase-4, -2, and -9 were simultaneously activated and p73 and Noxa induction were involved. ROS inhibition prevented p73 and Noxa expression but not p53 and p21 expression, suggesting a role for Noxa in p53-independent apoptosis in melanoma cells. Finally, we found that terfenadine induced autophagy, that can promote apoptosis. These findings demonstrate the great potential of terfenadine to kill melanoma cells through different cellular signaling pathways and could contribute to define new therapeutic strategies in melanoma.

Histamine and histamine receptor antagonists in cancer biology.

Histamine has been demonstrated to be involved in cell proliferation, embryonic development, and tumour growth. These various biological effects are mediated through the activation of specific histamine receptors (H1, H2, H3, and H4) that differ in their tissue expression patterns and functions. Although many in vitro and in vivo studies of the modulatory roles of histamine in tumour development and metastasis have been reported, the effect of histamine in the progression of some types of tumours remains controversial; however, recent findings on the role of histamine in the immune system have shed new light on this question. This review focuses on the recent advances in understanding the roles of histamine and its receptors in tumour biology. We report our recent observations of the anti-tumoural effect of H1 histamine antagonists on experimental and human melanomas. We have found that in spite of exogenous histamine stimulated human melanoma cell proliferation, clonogenic ability and migration activity in a dose-dependent manner, the melanoma tumour growth was not modulated by in vivo histamine treatment. On the contrary, terfenadine-treatment in vitro induced melanoma cell death by apoptosis and in vivo terfenadine treatment significantly inhibited tumour growth in murine models. These observations increase our understanding of cancer biology and may inspire novel anticancer therapeutic strategies.

Imprinting of mammalian male gametes is gene specific and does not occur at a single stage of differentiation.

Epigenetic modifications such as DNA methylation and alterations to chromatin structure have been proposed as hallmarks of imprinting in somatic cells after fertilization. In the germ cell line, gene imprinting needs to be reset in order to transmit the correct sex-specific imprinting pattern to the next generation. The precise timing of imprint erasure and re-establishment for many genes remains to be determined and precise molecular mechanisms of genomic imprinting have not yet been fully characterized. Here, we have analysed the methylation state and DNase-I sensitivity of two genes with reciprocal genomic imprinting (U2af1-rs1 and H19 genes) in a male mouse primordial germ cell (PGC) derived cell line (EG-1), isolated post-natal spermatogonia and mature sperm cells. Our results show that establishment of imprinting of the U2af1-rs1 and H19 genes during male germ cell differentiation occurs at different stages of differentiation. Furthermore, the presence of DNase-I hypersensitive sites may constitute a molecular marker to identify alleles and subsequently acquire the appropriate methylation imprint. We propose that this molecular identifier may be present or absent for a specific gene according to the sex of the gamete.

Terfenadine-induced apoptosis in human melanoma cells is mediated through Ca2+ homeostasis modulation and tyrosine kinase activity, independently of H1 histamine receptors.

In our previous works, we have demonstrated that terfenadine (TEF) induces DNA damage and apoptosis in human melanoma cell lines. In this present work, we have studied the effect of histamine on viability of A375 human melanoma cells and the cell-signalling pathways through which TEF may induce its apoptotic effect. We have found that exogenous histamine stimulates A375 melanoma cell proliferation in a dose- and time-dependent manner. Moreover, TEF-induced apoptosis seems to occur via other cellular pathways independent of the histamine-signalling system since co-treatment of histamine with TEF did not protect melanoma cells from the cytotoxic effect of TEF, and alpha fluoromethylhistidine did not induce the same cytotoxic effect of TEF. In addition, we have observed that knocking down the H1 histamine receptor (HRH1) by small interference RNA approach protects melanoma cells only slightly from TEF-induced apoptosis. To explore the molecular mechanisms responsible for histamine and TEF effect on the cell growth, we analysed intracellular cyclic nucleotides and Ca(2+) levels. TEF did not modify intracellular levels of cyclic adenosine 3',5'-monophosphate and cyclic guanine 3',5'-monophosphate; however, TEF induced a very sharp and sustained increase in cytosolic Ca(2+) levels in A375 melanoma cells. On the contrary, histamine did not modulate intracellular Ca(2+). TEF-induced Ca(2+) rise and apoptosis appear to be phospholipase C (PLC) dependent since neomycin and U73122, two inhibitors of PLC, abolished cytosolic Ca(2+) increase and protected the cells completely from cell death. Furthermore, inhibition of tyrosine kinase activity by genistein blocked cytosolic Ca(2+) rise and TEF-induced apoptosis. These results suggest that TEF modulates Ca(2+) homeostasis and induces apoptosis through other cellular pathways involving tyrosine kinase activity, independently of HRH1.

Interleukin-2 induces the proliferation of mouse primordial germ cells in vitro.

Primordial germ cells (PGCs) are the stem cell precursors of the germ line. Several growth factors contribute to enlarging the PGC population by acting as mitogens, survival factors or both. Interleukin-2 (IL-2) has a growth-promoting activity for T and B-lymphocytes, but its role in PGCs had not yet been studied. Here, we show that PGCs isolated from 10.5, 11.5 and 12.5 day postcoitum (dpc) mouse embryos constitutively express the three subunits (alpha, beta and gamma) of the IL-2 receptor (IL-2R). In contrast, IL-2 mRNA was not detected in these cells. However, the addition of recombinant IL-2 to the culture medium increased the number of PGCs in vitro via a mitogenic effect, as indicated by bromodeoxyuridine incorporation assays. Neutralization of the IL-2 receptor using anti-IL-2R subunit antibodies inhibited this IL-2-mediated proliferative effect on PGCs from 11.5 dpc embryos. Together, these data are indicative of a paracrine effect of IL-2 on PGC proliferation. In this regard, we also compared the effect of IL-2 with other compounds such as basic fibroblast growth factor (bFGF), steel factor, leukemia inhibitory factor and forskolin, and found that the degree of proliferation induced by IL-2 was similar to that induced by bFGF and forskolin. These observations support the notion that similar patterns of molecular signaling may underlie the developmental pathways of hematopoietic and germ stem cell precursors.

Epigenetic regulation of the imprinted U2af1-rs1 gene during retinoic acid-induced differentiation of embryonic stem cells.

Epigenetic modifications such as DNA methylation and changes in chromatin structure are changes in the chemical composition or structure of DNA that work by regulating gene expression. Their mechanisms of action have been generally studied in imprinted genes. The present work analyzes the involvement of these mechanisms in the expression of the U2af1-rs1 imprinted gene during the differentiation process of embryonic stem (ES) cells induced by retinoic acid. By DNA digestion with methylation-dependent or independent restriction enzymes and consecutive Southern blot, we have found that methylation of the U2af1-rs1 gene increases in differentiated ES cells and in embryoid bodies. However, northern blot and real-time reverse transcription-polymerase chain reaction analysis showed a higher expression of the U2af1-rs1 gene in differentiated ES cells and in embryoid bodies than in undifferentiated ones. On the other hand, the sensitivity to DNase-I assay demonstrated an open chromatin conformation for differentiated cells with regard to undifferentiated ES cells. Our results suggest that the expression of the U2af1-rs1 gene would be regulated by changes in chromatin structure rather than by DNA methylation during the RA-induced process of differentiation of ES cells.

Apoptosis of human T-cell acute lymphoblastic leukemia cells by diphenhydramine, an H1 histamine receptor antagonist.

Recently, it has been demonstrated that histamine plays an important role in the proliferation of normal and malignant cells. We have examined the effects of histamine, diphenhydramine, and cimetidine (H1 and H2 histamine receptor antagonists, respectively) on the in vitro proliferation of two human T-cell acute lymphoblastic leukemia cell lines, namely CCRF-CEM and Jurkat. Exogenous histamine did not alter the proliferation or viability of these cells. In contrast, diphenhydramine induced apoptosis in a dose- and time-dependent manner in both cell lines, whereas cimetidine failed to induce significant effects at similar concentrations. Diphenhydramine-induced apoptosis was evaluated in terms of morphology, flow cytometry, and the release of cytochrome c to the cytosol. The latter was partially mitigated by Bcl-2 overexpression. In human peripheral blood mononuclear cells, diphenhydramine inhibited cell proliferation without inducing apoptosis. Our findings indicate that endogenous histamine may be an important factor for the survival of CCRF-CEM, Jurkat, and peripheral blood mononuclear cells, and point to the potential application of H1 receptor antagonists as cytotoxic agents for the specific treatment of certain types of leukemia.