Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients.

BACKGROUND: Immunosuppressed organ-transplant recipients have an increased incidence of, and mortality from, skin cancer. Nicotinamide (vitamin B3) enhances the repair of ultraviolet (UV) radiation-induced DNA damage, reduces the cutaneous immunosuppressive effects of UV radiation, and reduces the incidence of keratinocyte cancers (including squamous-cell and basal-cell carcinomas) and actinic keratoses among high-risk immunocompetent patients. Whether oral nicotinamide is useful for skin-cancer chemoprevention in organ-transplant recipients is unclear. METHODS: In this phase 3 trial, we randomly assigned, in a 1:1 ratio, organ-transplant recipients who had had at least two keratinocyte cancers in the past 5 years to receive 500 mg of nicotinamide or placebo twice daily for 12 months. Participants were examined for skin lesions by dermatologists at 3-month intervals for 12 months. The primary end point was the number of new keratinocyte cancers during the 12-month intervention period. Secondary end points included the numbers of squamous-cell and basal-cell carcinomas during the 12-month intervention period, the number of actinic keratoses until 6 months after randomization, safety, and quality of life. RESULTS: A total of 158 participants were enrolled, with 79 assigned to the nicotinamide group and 79 to the placebo group. The trial was stopped early owing to poor recruitment. At 12 months, there were 207 new keratinocyte cancers in the nicotinamide group and 210 in the placebo group (rate ratio, 1.0; 95% confidence interval, 0.8 to 1.3; P = 0.96). No significant between-group differences in squamous-cell and basal-cell carcinoma counts, actinic keratosis counts, or quality-of-life scores were observed. Adverse events and changes in blood or urine laboratory variables were similar in the two groups. CONCLUSIONS: In this 12-month, placebo-controlled trial, oral nicotinamide therapy did not lead to lower numbers of keratinocyte cancers or actinic keratoses in immunosuppressed solid-organ transplant recipients. (Funded by the National Health and Medical Research Council; ONTRANS Australian New Zealand Clinical Trials Registry number, ACTRN12617000599370.).

H3K4me3 remodeling induced acquired resistance through O-GlcNAc transferase.

AIMS: Drivers of the drug tolerant proliferative persister (DTPP) state have not been well investigated. Histone H3 lysine-4 trimethylation (H3K4me3), an active histone mark, might enable slow cycling drug tolerant persisters (DTP) to regain proliferative capacity. This study aimed to determine H3K4me3 transcriptionally active sites identifying a key regulator of DTPPs. METHODS: Deploying a model of adaptive cancer drug tolerance, H3K4me3 ChIP-Seq data of DTPPs guided identification of top transcription factor binding motifs. These suggested involvement of O-linked N-acetylglucosamine transferase (OGT), which was confirmed by metabolomics analysis and biochemical assays. OGT impact on DTPPs and adaptive resistance was explored in vitro and in vivo. RESULTS: H3K4me3 remodeling was widespread in CPG island regions and DNA binding motifs associated with O-GlcNAc marked chromatin. Accordingly, we observed an upregulation of OGT, O-GlcNAc and its binding partner TET1 in chronically treated cancer cells. Inhibition of OGT led to loss of H3K4me3 and downregulation of genes contributing to drug resistance. Genetic ablation of OGT prevented acquired drug resistance in in vivo models. Upstream of OGT, we identified AMPK as an actionable target. AMPK activation by acetyl salicylic acid downregulated OGT with similar effects on delaying acquired resistance. CONCLUSION: Our findings uncover a fundamental mechanism of adaptive drug resistance that governs cancer cell reprogramming towards acquired drug resistance, a process that can be exploited to improve response duration and patient outcomes.

A systematic review and meta-analysis of locoregional treatments for in-transit melanoma.

BACKGROUND AND OBJECTIVES: In-transit melanoma (ITM) metastases present a therapeutic challenge and management decisions can be difficult. There are multiple treatments available, with differing efficacy, and supported by different levels of evidence. The primary objective was to perform a systematic review and where suitable, a meta-analysis of the literature reporting on the use of locoregional treatments for the management of ITM. METHODS: An independent review was conducted including a comprehensive search of the National Library of Medicine using PubMed, MEDLINE, Embase, and Cochrane Library databases. Key data were tabulated, synthesized and pooled to calculate relevant weighted effect sizes for each therapy using random-effect models. The statistical heterogeneity was calculated using the Higgins' method. RESULTS: Of the initial 32 612 articles identified, 57 original articles satisfied eligibility criteria. Eight treatment modalities were identified comprising: amputation (7); hyperthermic isolated limb perfusion (15); isolated limb infusion (8); carbon dioxide laser (9); PV-10 intralesional therapy (5); IL-2 intralesional therapy (8); imiquimod (7); diphenylcyclopropenone (3). Only amputation and topical imiquimod were suitable for formal meta-analysis. CONCLUSIONS: All of the assessed therapies have significant selection bias. Variable levels of evidence support the ongoing use of locoregional treatments and these may significantly improve disease-free survival.

The use of cinacalcet for the treatment of calciphylaxis in patients with chronic kidney disease: A comprehensive review.

Calciphylaxis is a rare but life-threatening condition, most commonly affecting patients with stage 4 or 5 chronic kidney disease. No universally accepted therapy exists so far. In an attempt to avoid surgical intervention with parathyroidectomy, which is of questionable efficacy and carries several risks, a number of noninvasive treatments have been trialled with variable success. These treatments are aimed at modifying risk factors for calciphylaxis, in particular hypercalcaemia, hyperphosphataemia and hyperparathyroidism. The aim of this review was to summarise the available evidence to determine the potential role of cinacalcet in the treatment of calciphylaxis in patients with chronic kidney disease. Demographic, clinical and laboratory data were retrospectively collected from the available English and non-English literature. Overall, there was a very high response rate (partial or complete) of calciphylaxis lesions to both cinacalcet monotherapy and cinacalcet as part of a combination therapy (83.4% and 82.8%, respectively). When examining complete response to treatment specifically, combination therapy with cinacalcet proved more efficacious than monotherapy (62.1% versus 41.7%). There was also an associated rapid reduction of intact parathyroid hormone over a period of 2-33 months in both groups. While there are limitations as to how our data can be interpreted due to the heterogeneity of the methods and follow-up of the included case reports and case series, prompt and consistent therapy including cinacalcet may help improve the disease outcome. Additional research needs to be performed in this area, to further define the optimal use of cinacalcet for the treatment of calciphylaxis.

Human lactoferricin derived di-peptides deploying loop structures induce apoptosis specifically in cancer cells through targeting membranous phosphatidylserine.

Host defense-derived peptides have emerged as a novel strategy for the development of alternative anticancer therapies. In this study we report on characteristic features of human lactoferricin (hLFcin) derivatives which facilitate specific killing of cancer cells of melanoma, glioblastoma and rhabdomyosarcoma compared with non-specific derivatives and the synthetic peptide RW-AH. Changes in amino acid sequence of hLFcin providing 9-11 amino acids stretched derivatives LF11-316, -318 and -322 only yielded low antitumor activity. However, the addition of the repeat (di-peptide) and the retro-repeat (di-retro-peptide) sequences highly improved cancer cell toxicity up to 100% at 20 µM peptide concentration. Compared to the complete parent sequence hLFcin the derivatives showed toxicity on the melanoma cell line A375 increased by 10-fold and on the glioblastoma cell line U-87mg by 2-3-fold. Reduced killing velocity, apoptotic blebbing, activation of caspase 3/7 and formation of apoptotic DNA fragments proved that the active and cancer selective peptides, e.g. R-DIM-P-LF11-322, trigger apoptosis, whereas highly active, though non-selective peptides, such as DIM-LF11-318 and RW-AH seem to kill rapidly via necrosis inducing membrane lyses. Structural studies revealed specific toxicity on cancer cells by peptide derivatives with loop structures, whereas non-specific peptides comprised α-helical structures without loop. Model studies with the cancer membrane mimic phosphatidylserine (PS) gave strong evidence that PS only exposed by cancer cells is an important target for specific hLFcin derivatives. Other negatively charged membrane exposed molecules as sialic acid, heparan and chondroitin sulfate were shown to have minor impact on peptide activity.

NR4A1-mediated apoptosis suppresses lymphomagenesis and is associated with a favorable cancer-specific survival in patients with aggressive B-cell lymphomas.

NR4A1 (Nur77) and NR4A3 (Nor-1) function as tumor suppressor genes as demonstrated by the rapid development of acute myeloid leukemia in the NR4A1 and NR4A3 knockout mouse. The aim of our study was to investigate NR4A1 and NR4A3 expression and function in lymphoid malignancies. We found a vastly reduced expression of NR4A1 and NR4A3 in chronic lymphocytic B-cell leukemia (71%), in follicular lymphoma (FL, 70%), and in diffuse large B-cell lymphoma (DLBCL, 74%). In aggressive lymphomas (DLBCL and FL grade 3), low NR4A1 expression was significantly associated with a non-germinal center B-cell subtype and with poor overall survival. To investigate the function of NR4A1 in lymphomas, we overexpressed NR4A1 in several lymphoma cell lines. Overexpression of NR4A1 led to a higher proportion of lymphoma cells undergoing apoptosis. To test the tumor suppressor function of NR4A1 in vivo, the stable lentiviral-transduced SuDHL4 lymphoma cell line harboring an inducible NR4A1 construct was further investigated in xenografts. Induction of NR4A1 abrogated tumor growth in the NSG mice, in contrast to vector controls, which formed massive tumors. Our data suggest that NR4A1 has proapoptotic functions in aggressive lymphoma cells and define NR4A1 as a novel gene with tumor suppressor properties involved in lymphomagenesis.

miR-206 controls LXRα expression and promotes LXR-mediated cholesterol efflux in macrophages.

Liver X receptors (LXRα and LXRß) are key transcription factors in cholesterol metabolism that regulate cholesterol biosynthesis/efflux and bile acid metabolism/excretion in the liver and numerous organs. In macrophages, LXR signaling modulates cholesterol handling and the inflammatory response, pathways involved in atherosclerosis. Since regulatory pathways of LXR transcription control are well understood, in the present study we aimed at identifying post-transcriptional regulators of LXR activity. MicroRNAs (miRs) are such post-transcriptional regulators of genes that in the canonical pathway mediate mRNA inactivation. In silico analysis identified miR-206 as a putative regulator of LXRα but not LXRß. Indeed, as recently shown, we found that miR-206 represses LXRα activity and expression of LXRα and its target genes in hepatic cells. Interestingly, miR-206 regulates LXRα differently in macrophages. Stably overexpressing miR-206 in THP-1 human macrophages revealed an up-regulation and miR-206 knockdown led to a down-regulation of LXRα and its target genes. In support of these results, bone marrow-derived macrophages (BMDMs) from miR-206 KO mice also exhibited lower expression of LXRα target genes. The physiological relevance of these findings was proven by gain- and loss-of-function of miR-206; overexpression of miR-206 enhanced cholesterol efflux in human macrophages and knocking out miR-206 decreased cholesterol efflux from MPMs. Moreover, we show that miR-206 expression in macrophages is repressed by LXRα activation, while oxidized LDL and inflammatory stimuli profoundly induced miR-206 expression. We therefore propose a feed-back loop between miR-206 and LXRα that might be part of an LXR auto-regulatory mechanism to fine tune LXR activity.

Gα13 mediates human cytomegalovirus-encoded chemokine receptor US28-induced cell death in melanoma.

US28, a constitutively active G-protein-coupled receptor encoded by the human cytomegalovirus, leads to mechanistically unknown programmed cell death. Here we show that expression of wild-type US28 in human melanoma cells leads to apoptotic cell death via caspase 3 activation along with reduced cell proliferation. Reduced tumor growth upon US28 expression was observed in a xenograft mouse model. The signaling mute US28R129A showed a reduced antiproliferative effect. On evaluating different G-proteins coupled to US28 for signal transduction, Gα13 was identified as the main G-protein executing the apoptotic effect. Silencing of Gα13 but not Gαq resulted in a substantial increase in cell survival. Overexpression of Gα13 but not Gαq and their GTPase deficient forms Gα13Q226L and GαqQ209L, respectively, confirmed the requirement of Gα13 for US28 mediated cell death. Increasing expression of Gα13 alone induced cell death underscoring its relay function for US28 mediated decreased cell viability. Further reduced expression of Gα13 in melanoma cell lines isolated from advanced lesions and melanoma tissue was observed. These findings identified Gα13 as crucial for US28-induced cell death, substantiating that the effect of US28 on cell fate depends on preferred G-protein binding.

Killing of melanoma cells and their metastases by human lactoferricin derivatives requires interaction with the cancer marker phosphatidylserine.

Despite favorable advancements in therapy cancer is still not curative in many cases, which is often due to inadequate specificity for tumor cells. In this study derivatives of a short cationic peptide derived from the human host defense peptide lactoferricin were optimized in their selective toxicity towards cancer cells. We proved that the target of these peptides is the negatively charged membrane lipid phosphatidylserine (PS), specifically exposed on the surface of cancer cells. We have studied the membrane interaction of three peptides namely LF11-322, its N-acyl derivative 6-methyloctanoyl-LF11-322 and its retro repeat derivative R(etro)-DIM-P-LF11-322 with liposomes mimicking cancerous and non-cancerous cell membranes composed of PS and phosphatidylcholine (PC), respectively. Calorimetric and permeability studies showed that N-acylation and even more the repeat derivative of LF11-322 leads to strongly improved interaction with the cancer mimic PS, whereas only the N-acyl derivative also slightly affects PC. Tryptophan fluorescence of selective peptide R-DIM-P-LF11-322 revealed specific peptide penetration into the PS membrane interface and circular dichroism showed change of its secondary structure by increase of proportion of ß-sheets just in the presence of the cancer mimic. Data correlated with in vitro studies with cell lines of human melanomas, their metastases and melanocytes, revealing R-DIM-P-LF11-322 to exhibit strongly increased specificity for cancer cells. This indicates the need of high affinity to the target PS, a minimum length and net positive charge, an adequate but moderate hydrophobicity, and capability of adoption of a defined structure exclusively in presence of the target membrane for high antitumor activity.

Distribution analyses of acquired melanocytic naevi on the trunk.

Acquired melanocytic naevi (AMN) are a well-known risk factor for the development of melanoma. Whereas previous studies have reviewed AMN distributions on individual body sites, the clinical distribution of AMN on the adult trunk has not been thoroughly investigated. We studied 40 participants with 1,282 naevi >5 mm, of which 781 were located on the trunk. Remarkably, 70% of these truncal naevi were located on the back and we produced a continuous mathematical description of decreasing naevus frequency moving dorsolaterally from the back midline. Furthermore we found that for both sexes the mean naevus size was larger on the front as well as on the lower trunk. This distinct pattern, whilst probably being unwritten knowledge (in the dermatology domain), has not been discussed before.

Chemokine receptors in gastric MALT lymphoma: loss of CXCR4 and upregulation of CXCR7 is associated with progression to diffuse large B-cell lymphoma.

Chemokine receptors have a crucial role in the development and progression of lymphoid neoplasms. To determine the chemokine receptor expression profile in gastric mucosa-associated lymphoid tissue (MALT) lymphoma, we performed an expression analysis of 19 chemokine receptors at mRNA levels by using real-time RT-PCR, as well as of five chemokine receptors--CCR8, CCR9, CXCR4, CXCR6 and CXCR7--by immunohistochemistry on human tissue samples of Helicobacter pylori-associated gastritis, gastric MALT lymphoma and gastric extranodal diffuse large B-cell lymphoma originating from MALT lymphoma (transformed MALT lymphoma). Following malignant transformation from H. pylori-associated gastritis to MALT lymphoma, an upregulation of CCR7, CXCR3 and CXCR7, and a loss of CXCR4 were detected. The transformation of gastric MALT lymphomas to gastric extranodal diffuse large B-cell lymphoma was accompanied by upregulation of CCR1, CCR5, CCR7, CCR8, CCR9, CXCR3, CXCR6, CXCR7 and XCR1. Remarkably, CXCR4 expression was exclusively found in nodal marginal B-cell lymphomas and nodal diffuse large B-cell lymphomas but not at extranodal manifestation sites, ie, in gastric MALT lymphomas or gastric extranodal diffuse large B-cell lymphomas. Furthermore, the incidence of bone marrow infiltration (16/51 with bone marrow involvement vs 35/51 with bone marrow involvement; Spearman ρ=0467 P<0.001) positively correlated with CXCR4 expression. CXCL12, the ligand of CXCR4 and CXCR7, was expressed by epithelial, endothelial and inflammatory cells, MALT lymphoma cells and was most strongly expressed by extranodal diffuse large B-cell lymphoma cells, suggesting at least in part an autocrine signaling pathway. Our data indicate that CXCR4 expression is associated with nodal manifestation and a more advanced stage of lymphomas and hence, might serve as useful clinical prognostic marker.

Skin cancer excisions and histopathology outcomes when following a contemporary population-based cohort longitudinally with 3D total-body photography.

Background: Skin cancer represents a significant health burden across the globe and early detection is critical to improve health outcomes. Three-dimensional (3D) total-body photography is a new and emerging technology which can support clinicians when they monitor people's skin over time. Objectives: The aim of this study was to improve our understanding of the epidemiology and natural history of melanocytic naevi in adults, and their relationship with melanoma and other skin cancers. Methods: Mind Your Moles was a 3-year prospective, population-based cohort study which ran from December 2016 to February 2020. Participants visited the Princess Alexandra Hospital every 6 months for 3 years to undergo both a clinical skin examination and 3D total-body photography. Results: A total of 1213 skin screening imaging sessions were completed. Fifty-six percent of participants (n = 108/193) received a referral to their own doctor for 250 lesions of concern, 101/108 (94%) for an excision/biopsy. Of those, 86 people (85%) visited their doctor and received an excision/biopsy for 138 lesions. Histopathology of these lesions found 39 non-melanoma skin cancers (across 32 participants) and six in situ melanomas (across four participants). Conclusions: 3D total-body imaging results in diagnosis of a high number of keratinocyte cancers (KCs) and their precursors in the general population.

The G-protein coupled receptor associated sorting protein GASP-1 regulates the signalling and trafficking of the viral chemokine receptor US28.

Human cytomegalovirus (HCMV) encodes the seven transmembrane(7TM)/G-protein coupled receptor (GPCR) US28, which signals and endocytoses in a constitutive, ligand-independent manner. Here we show that, following endocytosis, US28 is targeted to the lysosomes for degradation as a consequence of its interaction with the GPCR-associated sorting protein-1 (GASP-1). We find that GASP-1 binds to US28 in vitro and that disruption of the GASP-1/US28 interaction by either (i) overexpression of dominant negative cGASP-1 or by (ii) shRNA knock-down of endogenous GASP-1 is sufficient to inhibit the lysosomal targeting of US28 and slow its post-endocytic degradation. Furthermore, we found that GASP-1 affects US28-mediated signalling. The knock-down of endogenous GASP-1 impairs the US28-mediated Galphaq/PLC/inositol phosphate (IP) accumulation as well as the activation of the transcription factors Nuclear Factor-kappaB (NF-kappaB) and cyclic AMP responsive element binding protein (CREB). Overexpression of GASP-1 enhances both IP accumulation and transcription factor activity. Thus, GASP-1 is an important cellular determinant that not only regulates the post-endocytic trafficking of US28, but also regulates the signalling capacities of US28.

In search of a novel target - phosphatidylserine exposed by non-apoptotic tumor cells and metastases of malignancies with poor treatment efficacy.

This study was performed in the aim to identify potential targets for the development of novel therapy to treat cancer with poor outcome or treatment efficacy. We show that the negatively charged phospholipid phosphatidylserine (PS) is exposed in the outer leaflet of their plasma membrane not only in tumor cell lines, but also in metastases and primary cultures thereof, which contrasts with a lack of PS exposure by differentiated non-tumorigenic counterparts. Studied tumor cell lines were derived from non-tumorigenic and malignant melanomas, prostate- and renal cancer, glioblastoma and a rhabdomyosarcoma. Importantly, also metastases of melanoma expose PS and there is a correlation between malignancy of melanoma cell lines from different stages of tumor progression and PS exposure. The PS exposure we found was neither of apoptotic nor of experimental artificial origin. Finally potentially malignant and non-malignant cells could be differentiated by sorting of a primary cell culture derived from a glioblastoma based on PS exposure, which has so far not been possible within one culture due to lack of a specific marker. Our data provide clear evidence that PS could serve as uniform marker of tumor cells and metastases as well as a target for novel therapeutic approaches based on e.g. PS-specific host defense derived peptides.

Naphthoquinones from Onosma paniculata induce cell-cycle arrest and apoptosis in melanoma Cells.

Activity-guided fractionation of a petroleum ether-soluble extract of the roots of Onosma paniculata, which has been shown to affect the cell cycle and to induce apoptosis in melanoma cells, led to the isolation of several shikonin derivatives, namely, ß-hydroxyisovalerylshikonin (1), acetylshikonin (2), dimethylacrylshikonin (3), and a mixture of α-methylbutyrylshikonin and isovalerylshikonin (4+5). All compounds exhibited strong cytotoxicity against eight cancer cell lines and MRC-5 lung fibroblasts, with 3 found to possess the most potent cytotoxicity toward four melanoma cell lines (SBcl2, WM35, WM9, and WM164). Furthermore, 3 and the mixture of 4+5 were found to interfere with cell-cycle progression in these cell lines and led to an increasing number of cells in the subG1 region as well as to caspase-3/7 activation, indicating apoptotic cell death.

In-Depth Characterisation of Real-World Advanced Melanoma Patients Receiving Immunotherapies and/or Targeted Therapies: A Case Series.

Immunotherapies and targeted therapies have shown significant benefits for melanoma survival in the clinical trial setting. Much less is known about the characteristics and associated outcomes of those receiving such therapies in real-world settings. This study describes the characteristics of patients with advanced melanoma receiving immuno- and/or targeted therapies in a real-world setting. This prospective cohort study enrolled participants aged >18 years, diagnosed with advanced melanoma and currently undergoing immuno- and/or targeted therapies outside a clinical trial for follow-up with three-dimensional (3D) total-body imaging. Participants (n = 41) had a mean age of 62 years (range 29−86), 26 (63%) were male and the majority (n = 26, 63%) had ≥2 comorbidities. After a median of 39 months (range 1−52) follow-up, 59% (n = 24/41) of participants were alive. Despite multiple co-morbidities, the survival of participants with advanced melanoma treated using immuno- and/or targeted therapies was similar or better in our real-world setting compared to those treated in clinical trials using similar therapies. Larger studies powered to evaluate phenotypic and socio-economic characteristics, as well as specific comorbidities associated with survival in a real-world setting, are required to help determine those who will most benefit from immuno- and/or targeted therapies.

The Experience of 3D Total-Body Photography to Monitor Nevi: Results From an Australian General Population-Based Cohort Study.

BACKGROUND: Digital 3D total-body photography of the skin surface is an emerging imaging modality that can facilitate the identification of new and changing nevi. OBJECTIVE: We aimed to describe the experiences of study participants drawn from the general population who were provided 3D total-body photography and dermoscopy for the monitoring of nevi. METHODS: A population-based prospective study of adults aged 20-70 years from South East Queensland, Australia was conducted. Participants underwent 3D total-body photography and dermoscopy every 6 months over a 3-year period. Participants were asked to provide closed and open-ended feedback on their 3D total-body photography and dermoscopy experience (eg, comfort, trust, intended future use, and willingness to pay) at the halfway study time point (18 months) and final study time point (36 months). We assessed changes in participants' reported experience of 3D total-body photography, and patient characteristics associated with patient experience at the end of the study (36 months) were analyzed. RESULTS: A total of 149 participants completed the surveys at both the 18- and 36-month time points (median age 55, range 23-70 years; n=94, 63.1% were male). At the 18-month time point, most participants (n=103, 69.1%) stated they completely trusted 3D total-body imaging for the diagnosis and monitoring of their nevi, and this did not change at the 36-month (n=104, 69.8%) time point. The majority of participants reported that they were very comfortable or comfortable with the technology at both the 18- (n=138, 92.6%) and 36-month (n=140, 94%) time points, respectively; albeit, the number of participants reporting that they were very comfortable reduced significantly between the 18- and 36-month time points, from 71.1% (n=106) to 61.1% (n=91; P=.01). Almost all participants (n=140, 94%) would consider using this technology if it were to become commercially available, and this did not change during the two study time points. Half of the participants (n=74) cited barriers to participating in 3D total-body photography, including trust in the ability of this technology to detect and monitor suspicious lesions, digital privacy, cost, and travel requirements. CONCLUSIONS: The majority of participants expressed positive attitudes toward 3D total-body photography for the monitoring of their moles. Half of the participants identified potential barriers to uptake.

Genome-Scale DNA Methylation Analysis Identifies Repeat Element Alterations that Modulate the Genomic Stability of Melanocytic Nevi.

Acquired melanocytic nevi grow and persist in a stable form into adulthood. Using genome-wide methylation profiling, we evaluated 32 histopathologically and dermoscopically characterized nevi to identify the key epigenetic regulatory mechanisms involved in nevogenesis. Benign (69% globular and 31% nonspecific dermoscopic pattern) and dysplastic (95% reticular/nonspecific dermoscopic pattern) nevi were dissimilar, with only two shared differentially methylated loci. Benign nevi showed an increase in both genome-scale methylation and methylation of Alu/LINE-1 retrotransposable elements, a marker of genomic stability, as well as global methylation. In contrast, dysplastic nevi showed evidence for genomic instability through the hypomethylation of Alu/LINE-1 (Alu: P = 0.00019; LINE-1: P = 0.000035). Using dermoscopic classifications, reticular/nonspecific patterned nevi had 59,572 5'-C-phosphate-G-3' differentially methylated loci (Q < 0.05), whereas globular nevi had no significant differentially methylated loci. In reticular/nonspecific patterned nevi, the tumor suppressor PTEN had the greatest proportion of hypermethylated 5'-C-phosphate-G-3' loci in its promoter region than all other assayed gene promoters. The relative activity of reticular/nonspecific nevi was evidenced by 50,720 hypomethylated loci being enriched for accessible chromatin and 8,852 hypermethylated loci strongly enriched, for example, marks of active gene promoters, which suggests that gain of DNA methylation observed in these nevus types plays a role in gene regulation.