Aberrant DNA Methylation in Cutaneous Malignancies

5-Methylcytosine immunohistochemistry for predicting cutaneous melanoma prognosis

There is a correlation between DNA methylation and the diseased stage and poor survival. 5-methylcytosine (5-mC) is one of the epigenetic modifications of bases that researchers focus on. Staining with 5-mC immunohistochemistry was used to examine pathological samples taken from individuals diagnosed with cutaneous melanoma. Between Breslow levels 2 and 4, there was a significant difference in the H-score of 5-mC expression (p = 0.046). A significant reduction in 5-mC expression H-scores was seen in patients who were diagnosed with ulcers (p = 0.039). It was shown that patients with low 5-mC had a significantly worse overall survival rate (p = 0.027).

Genetic polymorphism in Methylenetetrahydrofolate Reductase chloride transport protein 6 (MTHFR CLCN6) gene is associated with keratinocyte skin cancer in a cohort of renal transplant recipients

Background

Renal transplant recipients (RTRs) are at increased risk of keratinocyte cancer (KC), especially cutaneous squamous cell carcinoma (cSCC). Previous studies identified a genetic variant of the Methylenetetrahydrofolate Reductase (MTHFR) gene, C677T, which conferred a risk for diagnosis of cSCC in Irish RTRs.

Objective

We sought to find further genetic variation in MTHFR and overlap genes that may be associated with a diagnosis of KC in RTRs.

Methods

Genotyping of a combined RTR population (n = 821) from two centres, Ireland (n = 546) and the USA (n = 275), was performed. This included 290 RTRs with KC and 444 without. Eleven single nucleotide polymorphisms (SNPs) in the MTHFR gene and seven in the overlap gene MTHFR Chloride transport protein 6 (CLCN6) were evaluated and association explored by time to event analysis (from transplant to first KC) using Cox proportional hazards model.

Results

Polymorphism at MTHFR CLCN6 (rs9651118) was significantly associated with KC in RTRs (HR 1.50, 95% CI 1.17–1.91, p < 0.00061) and cSCC (HR 1.63, 95% CI 1.14–2.34, p = 0.007). A separate SNP, MTHFR C677T, was also significantly associated with KC in the Irish population (HR 1.31, 95% CI 1.05–1.63, p = 0.016), but not American RTRs.

Conclusions

We report the association of a SNP in the MTHFR overlap gene, CLCN6 and KC in a combined RTR population. While the exact function of CLCN6 is not known, it is proposed to be involved in folate availability. Future applications could include incorporation in a polygenic risk score for KC in RTRs to help identify those at increased risk beyond traditional risk factor assessment.

UVB induces cutaneous squamous cell carcinoma progression by de novo ID4 methylation via methylation regulating enzymes

BACKGROUND

Little is known about whether UVB can directly influence epigenetic regulatory pathways to induce cutaneous squamous cell carcinoma (CSCC). This study aimed to identify epigenetic-regulated signalling pathways through global methylation and gene expression profiling and to elucidate their function in CSCC development.

METHODS

Global DNA methylation profiling by reduced representation bisulfite sequencing (RRBS) and genome-wide gene expression analysis by RNA sequencing (RNA-seq) in eight pairs of matched CSCC and adjacent normal skin tissues were used to investigate the potential candidate gene(s). Clinical samples, animal models, cell lines, and UVB irradiation were applied to validate the mechanism and function of the genes of interest.

FINDINGS

We identified the downregulation of the TGF-β/BMP-SMAD-ID4 signalling pathway in CSCC and increased methylation of inhibitor of DNA binding/differentiation 4 (ID4). In normal human and mouse skin tissues and cutaneous cell lines, UVB exposure induced ID4 DNA methylation, upregulated DNMT1 and downregulated ten-eleven translocation (TETs). Similarly, we detected the upregulation of DNMT1 and downregulation of TETs accompanying ID4 DNA methylation in CSCC tissues. Silencing of DNMT1 and overexpression of TET1 and TET2 in A431 and Colo16 cells led to increased ID4 expression. Finally, we showed that overexpression of ID4 reduced cell proliferation, migration, and invasion, and increased apoptosis in CSCC cell lines and reduced tumourigenesis in mouse models.

INTERPRETATION

The results indicate that ID4 is downregulated by UVB irradiation via DNA methylation. ID4 acts as a tumour suppressor gene in CSCC development.

FUNDING

CAMS Innovation Fund for Medical Sciences (CIFMS) (2016-I2M-3-021, 2017-I2M-1-017), the Natural Science Foundation of Jiangsu Province (BK20191136), and the Fundamental Research Funds for the Central Universities (3332019104).

Genome wide DNA methylation profiling identifies specific epigenetic features in high-risk cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer. Although most cSCCs have good prognosis, a subgroup of high-risk cSCC has a higher frequency of recurrence and mortality. Therefore, the identification of molecular risk factors associated with this aggressive subtype is of major interest. In this work we carried out a global-scale approach to investigate the DNA-methylation profile in patients at different stages, from premalignant actinic keratosis to low-risk invasive and high-risk non-metastatic and metastatic cSCC. The results showed massive non-sequential changes in DNA-methylome and identified a minimal methylation signature that discriminates between stages. Importantly, a direct comparison of low-risk and high-risk stages revealed epigenetic traits characteristic of high-risk tumours. Finally, a prognostic prediction model in cSCC patients identified a methylation signature able to predict the overall survival of patients. Thus, the analysis of DNA-methylation in cSCC revealed changes during the evolution of the disease through the different stages that can be of great value not only in the diagnosis but also in the prognosis of the disease.

DNA methylome and transcriptome alterations and cancer prevention by triterpenoid ursolic acid in UVB-induced skin tumor in mice

Nonmelanoma skin cancers (NMSCs) are the most common type of skin cancers. Major risk factors for NMSCs include exposure to ultraviolet (UV) irradiation. Ursolic acid (UA) is a natural triterpenoid enriched in blueberries and herbal medicinal products, and possess anticancer activities. This study focuses on the impact of UA on epigenomic, genomic mechanisms and prevention of UVB-mediated NMSC. CpG methylome and RNA transcriptome alterations of early, promotion and late stages of UA treated on UVB-induced NMSC in SKH-1 hairless mice were conducted using CpG methyl-seq and RNA-seq. Samples were collected at weeks 2, 15, and 25, and integrated bioinformatic analyses were performed to identify key pathways and genes modified by UA against UVB-induced NMSC. Morphologically, UA significantly reduced NMSC tumor volume and tumor number. DNA methylome showed inflammatory pathways IL-8, NF-κB, and Nrf2 pathways were highly involved. Antioxidative stress master regulator Nrf2, cyclin D1, DNA damage, and anti-inflammatory pathways were induced by UA. Nrf2, cyclin D1, TNFrsf1b, and Mybl1 at early (2 weeks) and late (25 weeks) stages were identified and validated by quantitative polymerase chain reaction. In summary, integration of CpG methylome and RNA transcriptome studies show UA alters antioxidative, anti-inflammatory, and anticancer pathways in UVB-induced NMSC carcinogenesis. Particularly, UA appears to drive Nrf2 and its upstream/downstream genes, anti-inflammatory (at early stages) and cell cycle regulatory (both early and late stages) genes, of which might contribute to the overall chemopreventive effects of UVB-induced MNSC. This study may provide potential biomarkers/targets for chemoprevention of early stage of UVB-induced NMSC in human.

CpG methyl-seq and RNA-seq epigenomic and transcriptomic studies on the preventive effects of Moringa isothiocyanate in mouse epidermal JB6 cells induced by the tumor promoter TPA

Epigenetic mechanisms play an important role in the early stages of carcinogenesis. Moringa isothiocyanate (MIC-1) is a major bioactive component derived from Moringa oleifera that has considerable antioxidant and anti-inflammatory effects. However, how MIC-1 influences epigenomic alterations in TPA-mediated JB6 cell carcinogenic transformation has not been evaluated. In this study, DNA and RNA isolated from TPA-induced JB6 cells in the presence or absence of MIC-1 were subjected to DNA Methyl-seq and RNA-seq to identify differentially methylated regions (DMRs) and differentially expressed genes (DEGs), respectively. When JB6 cells were challenged with TPA alone, there was a significant alteration of DEGs and DMRs; importantly, MIC-1 treatment reversed the patterns of some of the DEGs and DMRs. Transcriptome and CpG methylome profiling was performed in Ingenuity® Pathway Analysis (IPA) software to analyze the altered signaling pathways. Several anti-inflammatory responses, antioxidative stress-related pathways, and anticancer-related pathways were identified to be affected by MIC-1. These pathways included NF-kB, IL-1, LPS/IL-1-mediated inhibition of RXR function, Nrf2-mediated oxidative stress response, p53, and PTEN signaling pathways. Examination of correlations between transcriptomic and CpG methylome profiles yielded a small subset of genes, including the cancer-related genes Tmpt, Tubb3, and Muc2; the GTPases Gchfr and Igtp; and the cell cycle-related gene Cdc7. Taken together, our results show the potential contributions of epigenomic changes in DNA CpG methylation to gene expression to molecular pathways active in TPA-induced JB6 cells and demonstrate that MIC-1 can reverse these changes, supporting the potential preventive/treatment effects of MIC-1 against skin carcinogenesis.

Fucoxanthin Elicits Epigenetic Modifications, Nrf2 Activation and Blocking Transformation in Mouse Skin JB6 P+ Cells

Nuclear factor erythroid-2-related factor-2 (Nrf2 or NFE2L2) is a master regulator of the anti-oxidative stress response, which is involved in the defense against many oxidative stress/inflammation-mediated diseases, including anticancer effects elicited by an increasing number of natural products. Our previous studies showed that the epigenetic modification of the Nrf2 gene plays a key role in restoring the expression of Nrf2. In this study, we aimed to investigate the epigenetic regulation of Nrf2 by astaxanthin (AST) and fucoxanthin (FX), carotenoids which are abundant in microalgae and seaweeds, in mouse skin epidermal JB6 P+ cells. FX induced the anti-oxidant response element (ARE)-luciferase and upregulated the mRNA and protein levels of Nrf2 and Nrf2 downstream genes in HepG2-C8 cells overexpressing the ARE-luciferase reporter. Both FX and AST decreased colony formation in 12-Otetradecanoylphorbol-13-acetate (TPA)-induced transformation of JB6 P+ cells. FX decreased the methylation of the Nrf2 promoter region in the JB6 P+ cells by the bisulfite conversion and pyrosequencing. Both FX and AST significantly reduced DNA methyltransferase (DNMT) activity but did not affect histone deacetylase (HDAC) activity in JB6 P+ cells. In summary, our results show that FX activates the Nrf2 signaling pathway, induces the epigenetic demethylation of CpG sites in Nrf2 and blocks the TPA-induced transformation of JB6 P+ cells, indicating the potential health-promoting effects of FX in skin cancer prevention.

Correction to: In Vitro-In Vivo Dose Response of Ursolic Acid, Sulforaphane, PEITC, and Curcumin in Cancer Prevention

The citation of the author name "Ah-Ng Tony Kong" in PubMed is not the author's preference. Instead of "Kong AT", the author prefers "Kong AN".

In Vitro-In Vivo Dose Response of Ursolic Acid, Sulforaphane, PEITC, and Curcumin in Cancer Prevention

According to the National Center of Health Statistics, cancer was the culprit of nearly 600,000 deaths in 2016 in the USA. It is by far one of the most heterogeneous diseases to treat. Treatment for metastasized cancers remains a challenge despite modern diagnostics and treatment regimens. For this reason, alternative approaches are needed. Chemoprevention using dietary phytochemicals such as triterpenoids, isothiocyanates, and curcumin in the prevention of initiation and/or progression of cancer poses a promising alternative strategy. However, significant challenges exist in the extrapolation of in vitro cell culture data to in vivo efficacy in animal models and to humans. In this review, the dose at which these phytochemicals elicit a response in vitro and in vivo of a multitude of cellular signaling pathways will be reviewed highlighting Nrf2-mediated antioxidative stress, anti-inflammation, epigenetics, cytoprotection, differentiation, and growth inhibition. The in vitro-in vivo dose response of phytochemicals can vary due, in part, to the cell line/animal model used, the assay system of the biomarker used for the readout, chemical structure of the functional analog of the phytochemical, and the source of compounds used for the treatment study. While the dose response varies across different experimental designs, the chemopreventive efficacy appears to remain and demonstrate the therapeutic potential of triterpenoids, isothiocyanates, and curcumin in cancer prevention and in health in general.

Aberrant Methylation Changes Detected in Cutaneous Squamous Cell Carcinoma of Immunocompetent Individuals

In order to elucidate the role of epigenetic alterations in the development of cutaneous squamous cell carcinoma (SCC), we analyzed both gene-specific promoter hypermethylation and repetitive sequence hypomethylation in cutaneous SCC as well as normal skin tissue samples. We showed that methylation of DAPK1 and CDH13 was associated with cutaneous SCC. While methylation frequency of DAPK1 was increased from sun-protected normal skin, sun-exposed normal skin, perilesional to lesional tissues, methylation of CDH13 was almost exclusively detected in cutaneous SCC tissues. Further, methylation of DAPK1 and CDH13 was neither correlated with the presence of HPV nor with the presence of p53 mutations in lesional skin tissues. Finally, we detected trend of reduced methylation level of repetitive sequences from sun-protected, sun-exposed normal skin samples to perilesional, and lesional tissues from SCC patients. We conclude that both gene-specific hypermethylation and repetitive sequence hypomethylation are present in cutaneous SCC tissue samples; these epigenetic changes might represent an independent pathway in the development of cutaneous SCC.

The Impact of External Factors on the Epigenome: In Utero and over Lifetime

Epigenetic marks change during fetal development, adult life, and aging. Some changes play an important role in the establishment and regulation of gene programs, but others seem to occur without any apparent physiological role. An important future challenge in the field of epigenetics will be to describe how the environment affects both of these types of epigenetic change and to learn if interaction between them can determine healthy and disease phenotypes during lifetime. Here we discuss how chemical and physical environmental stressors, diet, life habits, and pharmacological treatments can affect the epigenome during lifetime and the possible impact of these epigenetic changes on pathophysiological processes.

β-Adducin siRNA disruption of the spectrin-based cytoskeleton in differentiating keratinocytes prevented by calcium acting through calmodulin/epidermal growth factor receptor/cadherin pathway

Here, we report that siRNA transfection of β-adducin significantly disrupted the spectrin-based cytoskeleton and cytoskeletal arrangements of both β-adducin and PKCδ by substantially inhibiting the expression of β-adducin, spectrin and PKCδ proteins in differentiating keratinocytes. However, extracellular Ca2+ treatment blocked the inhibitory effects of the β-adducin siRNA. Ca2+ also prevented the significant down-regulation of two differentiation markers involucrin and K1/10 and the distinct up-regulation of proliferation marker K14 in β-adducin siRNA transfected keratinocytes. In addition, β-adducin knockdown resulted in a substantial reduction of epidermal growth factor receptor (EGFR), cadherin and β-catenin and enhanced phosphorylation of EGFR on tyrosine 1173 and Ca2+ prevented these changes. Furthermore, Ca2+ blocked the inhibitory effects of β-adducin siRNA on the expression of calmodulin, phosphorylated-calmodulin (P-CaM((Tyr138))) and myristoylated alanine-rich C-kinase substrate (MARCKS) in keratinocytes. Co-immunoprecipitation studies further revealed that calmodulin, not MARCKS, strongly interacted with EGFR, cadherin and β-catenin. Our data suggest that Ca2+ plays an important role in regulating the expression and function of β-adducin to sustain normal organization of the spectrin-based cytoskeleton and the differentiation properties in keratinocytes through the calmodulin/EGFR/cadherin signaling pathway.

Epigenetic alterations in sporadic basal cell carcinomas

Basal cell carcinoma (BCC) is the most common malignant human neoplasm characterized by slow growth and virtual absence of metastases. Recently, it has become evident that along with genetic mutations epigenetic alterations play a key role in the pathogenesis of human cancer. We searched for promoter methylation of hMLH1, RASSF1A, DAPK, APC, DCR1 and DCR2 genes and BRAF mutations in BCCs in association with the clinicopathological parameters and the histological subtypes of the tumours. Fifty-two BCCs, 17 FFPE along with 35 fresh tissue samples with matching normal tissues for 26 cases were analyzed by methylation-specific PCR to assess the methylation status of hMLH1, RASSF1A, DAPK, APC, DCR1 and DCR2 genes after sodium bisulfite treatment of the tumour and normal DNA. hMLH1 and DCR1 gene expression was investigated by immunohistochemistry. BRAF mutations were studied by high resolution melting analysis. Methylation was detected at a variable frequency of 44, 33, 32.5, 32 and 14 % of DCR2, APC, DCR1, RASSF1 and DAPK promoters, respectively, whereas methylation of hMLH1 promoter was absent. No BRAF mutations were found. There was no correlation between the frequency of the promoter methylation of the above-mentioned genes and the clinicopathological features or the histological subtypes of the tumours. The relatively high frequency of RASSF1A, DCR1, DCR2 and APC promoter methylation may imply that methylation constitutes an important pathway in the tumourigenesis of BCC that could provide new opportunities in developing epigenetic therapies for BCC patients. Nevertheless, further studies are needed to establish the above-mentioned hypothesis.

UVB irradiation does not directly induce detectable changes of DNA methylation in human keratinocytes

Unprotected exposure to UVB radiation from the sun and the resulting DNA damage are thought to be responsible for physiological changes in the skin and for a variety of skin cancers, including basal cell and squamous cell carcinoma and malignant melanoma. Although the mutagenic effects of UVB have been well documented and studied mechanistically, there is only limited information as to whether UV light may also be responsible for inducing epigenetic changes in the genome of exposed cells. DNA methylation is a stable epigenetic modification involved in gene control. To study the effects of UVB radiation on DNA methylation, we repeatedly exposed normal human keratinocytes to a UVB light source. After a recovery period, we analyzed global DNA methylation patterns in the irradiated and control cells using the methylated-CpG island recovery assay (MIRA) method in combination with high-resolution microarrays. Bioinformatics analysis revealed only a limited number of possible differences between UVB-exposed and control cells. However, these minor apparent changes could not be independently confirmed by bisulfite sequencing-based approaches. This study reveals that UVB irradiation of keratinocytes has no recognizable global effect on DNA methylation patterns and suggests that changes in DNA methylation, as observed in skin cancers, are not immediate consequences of human exposure to solar UVB irradiation.

Epigenetic changes in Basal Cell Carcinoma affect SHH and WNT signaling components

Background

The genetic background of Basal Cell Carcinoma (BCC) has been studied extensively, while its epigenetic makeup has received comparatively little attention. Epigenetic alterations such as promoter hypermethylation silence tumor suppressor genes (TSG) in several malignancies.

Objective

We sought to analyze the promoter methylation status of ten putative (tumor suppressor) genes that are associated with Sonic Hedgehog (SHH), WNT signaling and (hair follicle) tumors in a large series of 112 BCC and 124 healthy control samples by methylation-specific PCR.

Results

Gene promoters of SHH (P = 0.016), adenomatous polyposis coli (APC) (P = 0.003), secreted frizzled-related protein 5 (SFRP5) (P = 0.004) and Ras association domain family 1A (RASSF1A) (P = 0.023) showed significantly more methylation in BCC versus normal skin. mRNA levels of these four genes were reduced for APC and SFRP5 in BCC (n = 6) vs normal skin (n = 6). Down regulation of SHH, APC and RASSF1A could be confirmed on protein level as well (P<0.001 for all genes) by immunohistochemical staining. Increased canonical WNT activity was visualized by β-catenin staining, showing nuclear β-catenin in only 28/101 (27.7%) of BCC. Absence of nuclear β-catenin in some samples may be due to high levels of membranous E-cadherin (in 94.1% of the samples).

Conclusions

We provide evidence that promoter hypermethylation of key players within the SHH and WNT pathways is frequent in BCC, consistent with their known constitutive activation in BCC. Epigenetic gene silencing putatively contributes to BCC tumorigenesis, indicating new venues for treatment.

Genetics and epigenetics of cutaneous malignant melanoma: a concert out of tune

Cutaneous malignant melanoma (CMM) is the most life-threatening neoplasm of the skin and is considered a major health problem as both incidence and mortality rates continue to rise. Once CMM has metastasized it becomes therapy-resistant and is an inevitably deadly disease. Understanding the molecular mechanisms that are involved in the initiation and progression of CMM is crucial for overcoming the commonly observed drug resistance as well as developing novel targeted treatment strategies. This molecular knowledge may further lead to the identification of clinically relevant biomarkers for early CMM detection, risk stratification, or prediction of response to therapy, altogether improving the clinical management of this disease. In this review we summarize the currently identified genetic and epigenetic alterations in CMM development. Although the genetic components underlying CMM are clearly emerging, a complete picture of the epigenetic alterations on DNA (DNA methylation), RNA (non-coding RNAs), and protein level (histone modifications, Polycomb group proteins, and chromatin remodeling) and the combinatorial interactions between these events is lacking. More detailed knowledge, however, is accumulating for genetic and epigenetic interactions in the aberrant regulation of the INK4b-ARF-INK4a and microphthalmia-associated transcription factor (MITF) loci. Importantly, we point out that it is this interplay of genetics and epigenetics that effectively leads to distorted gene expression patterns in CMM.

Induction of cyclin D1 by arsenite and UVB-irradiation in human keratinocytes

Arsenic is an environmental pollutant with carcinogenic properties that is found in many regions of the world but that poses a health risk primarily in economically disadvantaged areas. In these areas, arsenic ingestion affects various tissues, especially skin in which it acts as a comutagen with the ultraviolet component of solar radiation. Both epidemiological and experimental evidence indicates that arsenic and ultraviolet radiation act on signaling pathways that effect the expression of cyclin D1. We have previously employed an in vitro model system of human epidermal keratinocytes to study the effects of submicromolar concentrations of sodium arsenite on cyclin D1 expression. Here, we employed this system to demonstrate concordant cyclin D1-related induction profiles of ultraviolet B radiation and arsenite using cDNA microarray analysis. We also show that both of these agents act epigenetically to bring about demethylation of the cyclin D1 promoter.

Epigenetic biomarkers in skin cancer

Epigenetic aberrations have been associated with cutaneous melanoma tumorigenesis and progression including dysregulated DNA gene promoter region methylation, histone modification, and microRNA. Several of these major epigenetic aberrations have been developed into biomarkers. Epigenetic biomarkers can be detected in tissue and in blood as circulating DNA in melanoma patients. There is strong evidence that biomarkers in cutaneous melanoma will have an important role as companions to therapeutics and overall patient management. Important progress has been made in epigenetic melanoma biomarker development and verification of clinical utility, and this review discusses some of the key current developments and existing challenges.

UVA-induced epigenetic regulation of P16(INK4a) in human epidermal keratinocytes and skin tumor derived cells

UVA-radiation (315-400 nm) has been demonstrated to be capable of inducing DNA damage and is regarded as a carcinogen. While chromosomal aberrations found in UVA-irradiated cells and skin tumors provided evidence of the genetic involvement in UVA-carcinogenesis, its epigenetic participation is still illusive. We thus analysed the epigenetic patterns of 5 specific genes that are involved in stem cell fate (KLF4, NANOG), telomere maintenance (hTERT) and tumor suppression in cell cycle control (P16(INK4a), P21(WAFI/CIPI)) in chronically UVA-irradiated HaCaT human keratinocytes. A striking reduction of the permissive histone mark H3K4me3 has been detected in the promoter of P16(INK4a) (4-fold and 9-fold reduction for 10 and 15 weeks UVA-irradiated cells, respectively), which has often been found deregulated in skin cancers. This alteration in histone modification together with a severe promoter hypermethylation strongly impaired the transcription of P16(INK4a) (20-fold and 40-fold for 10 weeks and 15 weeks UVA-irradiation, respectively). Analysis of the skin tumor-derived cells revealed the same severe impairment of the P16(INK4a) transcription attributed to promoter hypermethylation and enrichment of the heterochromatin histone mark H3K9me3 and the repressive mark H3K27me3. Less pronounced UVA-induced epigenetic alterations were also detected for the other genes, demonstrating for the first time that UVA is able to modify transcription of skin cancer associated genes by means of epigenetic DNA and histone alterations.

Molecular markers in cutaneous squamous cell carcinoma

Nonmelanoma skin carcinoma (NMSC) is the most frequent cancer in the USA with over 1.3 million new diagnoses a year; however due to an underappreciation of its associated mortality and growing incidence and its ability to be highly aggressive, the molecular mechanism is not well delineated. Whereas the molecular profiles of melanoma have been well characterized, those for cutaneous squamous cell carcinoma (cSCC) have trailed behind. This importance of the new staging paradigm is linked to the ability currently to better clinically cluster similar biologic behavior in order to risk-stratify lesions and patients. In this paper we discuss the trends in NMSC and the etiologies for the subset of NMSC with the most mortality, cutaneous SCC, as well as where the field stands in the discovery of a molecular profile. The molecular markers are highlighted to demonstrate the recent advances in cSCC.

The human health effects of ozone depletion and interactions with climate change

Depletion of the stratospheric ozone layer has led to increased solar UV-B radiation (280-315 nm) at the surface of the Earth. This change is likely to have had an impact on human exposure to UV-B radiation with consequential detrimental and beneficial effects on health, although behavioural changes in society over the past 60 years or so with regard to sun exposure are of considerable importance. The present report concentrates on information published since our previous report in 2007. The adverse effects of UV radiation are primarily on the eye and the skin. While solar UV radiation is a recognised risk factor for some types of cataract and for pterygium, the evidence is less strong, although increasing, for ocular melanoma, and is equivocal at present for age-related macular degeneration. For the skin, the most common harmful outcome is skin cancer, including melanoma and the non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma. The incidence of all three of these tumours has risen significantly over the past five decades, particularly in people with fair skin, and is projected to continue to increase, thus posing a significant world-wide health burden. Overexposure to the sun is the major identified environmental risk factor in skin cancer, in association with various genetic risk factors and immune effects. Suppression of some aspects of immunity follows exposure to UV radiation and the consequences of this modulation for the immune control of infectious diseases, for vaccination and for tumours, are additional concerns. In a common sun allergy (polymorphic light eruption), there is an imbalance in the immune response to UV radiation, resulting in a sun-evoked rash. The major health benefit of exposure to solar UV-B radiation is the production of vitamin D. Vitamin D plays a crucial role in bone metabolism and is also implicated in protection against a wide range of diseases. Although there is some evidence supporting protective effects for a range of internal cancers, this is not yet conclusive, but strongest for colorectal cancer, at present. A role for vitamin D in protection against several autoimmune diseases has been studied, with the most convincing results to date for multiple sclerosis. Vitamin D is starting to be assessed for its protective properties against several infectious and coronary diseases. Current methods for protecting the eye and the skin from the adverse effects of solar UV radiation are evaluated, including seeking shade, wearing protective clothing and sunglasses, and using sunscreens. Newer possibilities are considered such as creams that repair UV-induced DNA damage, and substances applied topically to the skin or eaten in the diet that protect against some of the detrimental effects of sun exposure. It is difficult to provide easily understandable public health messages regarding "safe" sun exposure, so that the positive effects of vitamin D production are balanced against the negative effects of excessive exposure. The international response to ozone depletion has included the development and deployment of replacement technologies and chemicals. To date, limited evidence suggests that substitutes for the ozone-depleting substances do not have significant effects on human health. In addition to stratospheric ozone depletion, climate change is predicted to affect human health, and potential interactions between these two parameters are considered. These include altering the risk of developing skin tumours, infectious diseases and various skin diseases, in addition to altering the efficiency by which pathogenic microorganisms are inactivated in the environment.

MAGE-A10 is a nuclear protein frequently expressed in high percentages of tumor cells in lung, skin and urothelial malignancies

MAGE-A10 is a highly immunogenic member of the MAGE-A family of cancer/testis tumor-associated antigens (C/T TAAs). Studies performed with broadly reactive antibodies have helped to initially characterize this TAA. However, no specific reagents have been developed so far, thus preventing a thorough analysis of its expression in healthy and tumoral tissues. We have produced MAGE-A10 gene product in soluble recombinant form, and we have used it to generate specific monoclonal antibodies (mAbs). One of these reagents, recognizing an epitope located at the COOH terminus of the MAGE-A10 gene product, was used to stain a multitumor tissue microarray comprising more than 2,500 paraffin-embedded specimens including healthy tissues, benign tumors and malignancies of different histological origin. MAGE-A10 protein was identified as an intranuclear protein of an apparent molecular weight of 70 kDa, expressed in normal spermatogonia and spermatocytes but in no other healthy tissue. Most importantly, this C/T TAA appears to be expressed in high (>50%) percentages of cancer cells from a number of malignancies, including lung, skin and urothelial tumors. Unexpectedly, high expression of MAGE-A10 TAA at the protein level was also detectable in gynecological malignancies and stomach and gall bladder cancers. The characterization of MAGE-A10-specific reagents might set the stage for the development of targeted active immunotherapy by clarifying potential indications and by allowing the selection of patients eligible for treatment and the monitoring of its effectiveness.

Examination of AKAP12 promoter methylation in skin cancer using methylation-sensitive high-resolution melting analysis

BACKGROUND

A kinase anchor protein 12 (AKAP12/gravin) belongs to a family of scaffold proteins and organizes protein kinase (PK)A and PKC. DNA hypermethylation in the AKAP12 promoter region has been reported in a variety of human cancers with the exception of skin cancer. Methylation-specific high-resolution melting (MS-HRM) analysis is a novel tool for analysis of promoter methylation.

AIM

To use MS-HRM analysis to detect the methylation levels of the AKAP12 gene in skin samples.

METHODS

In total, 195 samples, including basal cell carcinoma, squamous cell carcinoma and actinic keratosis were examined. MS-HRM analysis was used to detect methylation levels of the AKAP12 gene in these samples.

RESULTS

MS-HRM analysis successfully detected the methylation of AKAP12 in skin samples. The frequencies of AKAP12 methylation in all three types of skin abnormalities were significantly higher than in normal tissues.

CONCLUSIONS

Application of MS-HRM analysis proved to be a fast and high-throughput method to investigate the epigenetic status of AKAP12. Methylation of AKAP12 can be detected in different skin abnormalities.

Targeting histone deacetyalses in the treatment of B- and T-cell malignancies

HDAC inhibitors (HDACI) are now emerging as one of the most promising new classes of drugs for the treatment of select forms of non-Hodgkin’s lymphoma (NHL). They are particularly active in T-cell lymphomas, possibly hodgkin’s lymphoma and indolent B cell lymphomas. Presently, two of these agents, vorinostat and romidepsin, have been approved in the US for the treatment of relapsed and refractory cutaneous T cell lymphomas (CTCL). Initially, these agents were developed with the idea that they affected transcriptional activation and thus gene expression, by modulating chromatin condensation and decondensation. It is now clear that their effects go beyond chromatin and by affecting the acetylation status of histones and other intra-cellular proteins, they modify gene expression and cellular function via multiple pathways. Gene expression profiles and functional genetic analysis has led to further understanding of the various molecular pathways that are affected by these agents including cell cycle regulation, pathways of cellular proliferation, apoptosis and angiogenesis all important in lymphomagenesis. There is also increasing data to support the effects of these agents on T cell receptor and immune function which may explain the high level of activity of these agents in T cell lymphomas and hodgkin’s lymphoma. There is ample evidence of epigenetic dysregulation in lymphomas which may underlie the mechanisms of action of these agents but how these agents work is still not clear. Current HDAC inhibitors can be divided into at least four classes based on their chemical structure. At present several of these HDAC inhibitors are in clinical trials both as single agents and in combination with chemotherapy or other biological agents. They are easy to administer and are generally well tolerated with minimal side effects. Different dosing levels and schedules and the use of isospecific HDAC inhibitors are some of the strategies that are being employed to increase the therapeutic effect of these agents in the treatment of lymphomas. There may also be class differences that translate into specific activity against different lymphoma. HDAC inhibitors will likely be incorporated into combinations of targeted therapies both in the upfront and relapsed setting for lymphomas.

Vitamin D in health and disease: an insight into traditional functions and new roles for the 'sunshine vitamin'

Vitamin D is unique among the vitamins in that man can synthesise it via the action of UV radiation upon the skin. This combined with its ability to act on specific target tissues via vitamin D receptors (VDR) make its classification as a steroid hormone more appropriate. While vitamin D deficiency is a recognised problem in some northern latitude countries, recent studies have shown that even in sunny countries, such as Australia, vitamin D deficiency may be more prevalent than first thought. Vitamin D is most well known for its role in bone health; however, the discovery of VDR on a wide variety of tissue types has also opened up roles for vitamin D far beyond traditional bone health. These include possible associations with autoimmune diseases such as multiple sclerosis and inflammatory bowel diseases, cancer, CVD and muscle strength. First, this paper presents an overview of the two sources of vitamin D: exposure to UVB radiation and food sources of vitamin D, with particular focus on both Australian and international studies on dietary vitamin D intake and national fortification strategies. Second, the paper reviews recent epidemiological and experimental evidence linking vitamin D and its role in health and disease for the major conditions linked to suboptimal vitamin D, while identifying significant gaps in the research and possible future directions for research.

CDKN2A-CDKN2B deletion defines an aggressive subset of cutaneous T-cell lymphoma

Inactivation of the CDKN2A-CDKN2B locus has been reported in the most frequent subtypes of cutaneous T-cell lymphomas (CTCLs), mycosis fungoides, Sézary syndrome (SS) and CD30+ cutaneous anaplastic large cell lymphoma. To investigate whether genetic or epigenetic inactivation of CDKN2A-CDKN2B is more specifically observed in certain CTCL subtypes with clinical impact, we used array-comparative genomic hybridization, quantitative PCR, interphase fluorescent in situ hybridization and methylation analyses of p14(ARF) p16(INK4A) and p15(INK4B) promoters. We studied 67 samples from 58 patients with either transformed mycosis fungoides (n=24), SS (n=16) or CD30+ cutaneous anaplastic large cell lymphoma (n=18). We observed combined CDKN2A-CDKN2B deletion in both transformed mycosis fungoides (n=17, 71%) and SS patients (n=7, 44%), but, surprisingly, in only one CD30+ cutaneous anaplastic large cell lymphoma case. Interphase fluorescent in situ hybridization showed 9p21 loss in 17 out of 19 cases, with 9p21 deletion indicating either hemizygous (n=4) or homozygous (n=2) deletion, with mixed patterns in most patients (n=11). The limited size of 9p21 deletion was found to account for false-negative detection by either BAC arrays (n=9) or fluorescent in situ hybridization (n=2), especially in patients with Sézary syndrome (n=6). Methylation was found to be restricted to the p15(INK4B) gene promoter in patients with or without 9p21 deletion and did not correlate with prognosis. In contrast, CDKN2A-CDKN2B genetic loss was strongly associated with a shorter survival in CTCL patients (P=0.002) and more specifically at 24 months in transformed mycosis fungoides and SS patients (P=0.02). As immunohistochemistry for p16(INK4A) protein was not found to be informative, the genetic status of the CDKN2A-CDKN2B locus would be relevant in assessing patients with epidermotropic CTCLs in order to identify those cases where the disease was more aggressive.

FOXE1 is a target for aberrant methylation in cutaneous squamous cell carcinoma

BACKGROUND

Several cancer-related genes are silenced by promoter hypermethylation in skin cancers. However, to date the somatic epigenetic events that occur in cutaneous squamous cell carcinoma (SCC) tumorigenesis have not been well defined.

OBJECTIVES

To examine epigenetic abnormalities of FOXE1, a gene located on chromosome 9q22, a region frequently lost in SCC.

METHODS

We investigated the methylation status of FOXE1 in 60 cases of cutaneous SCC by methylation-specific polymerase chain reaction, and comparatively examined mRNA and protein expression by real-time polymerase chain reaction and Western blot, respectively.

RESULTS

We found a higher frequency of FOXE1 promoter hypermethylation in SCCs (55%), as compared with the adjacent uninvolved skin (12%) and blood control samples (9.5%). FOXE1 methylation was frequently seen in association with a complete absence of or downregulated gene expression. Treatment with the demethylating agent 5-Aza-2'-deoxycytidine resulted in profound reactivation of FOXE1 expression.

CONCLUSIONS

These results indicate that FOXE1 is a crucial player in development of cutaneous SCC.

Aberrant DNA methylation in skin diseases

Epigenetic mechanisms are involved in regulating cell growth and differentiation without inducing changes in the gene sequence. The main epigenetic mechanisms include DNA methylation, histone modification, and microRNA. Recent studies indicate that aberrant DNA methylation is a common feature of many human disorders, including cancer, autoimmune diseases, heart diseases, skin diseases, and others. Skin diseases comprise various diseases that have a complex etiology and pathogenesis, including genetics and acquired factors such as environment and diet. These acquired factors often have pathogenic effects through modification of DNA and histones, of which DNA methylation is the most common mechanism. Aberrant DNA methylation has been demonstrated in skin diseases, including skin tumors and autoimmune-related skin disorders. Herein, we review the role of DNA methylation in the pathogenesis of skin diseases.

Epigenetics of cutaneous melanoma

Tumorigenesis is traditionally thought to be caused by the imbalance between oncogenes and tumor-suppressor genes. Epigenetics is a recently described phenomenon that uses an alternative mechanism to explain the transcriptional inactivation of tumor-suppressor genes predominantly by hypermethylation of the promoter regions. Hypermethylation of these regions has been described extensively in many neoplasms, including cutaneous melanoma. Histone modification, primarily by acetylation and deacetylation, is a current potential target for melanoma therapy, but more research is required to understand the mechanisms involved and the therapeutic effectiveness of regimens involving these agents. These mechanisms not only are important for understanding the origin and progression of neoplasms but also have important potential therapeutic implications. Understanding the epigenetic mechanisms involved in melanoma can provide valuable information with significant implications in diagnosis, treatment, and prevention.

From UVs to metastases: modeling melanoma initiation and progression in the mouse

Cutaneous malignant melanoma is highly invasive and capable of metastasizing to distant sites where it is typically resistant to available therapy. While striving to prevent or eradicate melanoma, researchers have two significant advantages not shared by those working on many other cancers. The main environmental etiological agent, UV radiation, is known and melanocytic lesions are excisable for molecular analysis from most stages. Yet knowledge about how UV initiates melanoma has been insufficient to achieve prevention, and the understanding of metastatic mechanisms has been inadequate to reduce mortality. Here, we review the value of melanoma mouse models, focusing on these critical early and late stages.

The methylation pattern of p16INK4a gene promoter in psoriatic epidermis and its clinical significance

BACKGROUND

Alteration of the p16INK4a gene by epigenetic changes has been described in some hyperproliferative skin diseases, but its importance in psoriasis has not yet been established.

OBJECTIVES

To investigate the methylation status of the p16INK4a gene in psoriatic epidermis, its clinical significance and the possible epigenetic mechanisms of psoriasis.

METHODS

DNA and RNA specimens were obtained from the lesional epidermis of 56 patients with plaque psoriasis. Methylation-specific polymerase chain reaction (PCR) and DNA sequencing were used to detect the density and sites of methylation in the p16INK4a promoter region. The reverse transcription-PCR technique was applied to detect the mRNA expression of p16INK4a.

RESULTS

p16INK4a gene promoter methylation was shown in 17 of 56 (30%) patients with psoriasis. Psoriasis Area and Severity Index scores in patients showing methylation were higher than in those who did not (P<0.05). The mRNA expression level of p16INK4a in the methylated group was significantly lower than in the unmethylated group (t=2.515, P=0.015). In the methylated group, about 50% of the CpG islands were methylated in the promoter region.

CONCLUSIONS

Overall, methylation of the p16INK4a gene promoter is found in psoriatic epidermis, which is associated with the mRNA level of p16INK4a expression and activity of the disease. These data indicate that methylation of the p16INK4a promoter may play a potential role in the pathogenesis of psoriasis.

Decreased expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in basal cell carcinomas

Thymidine phosphorylase (TP)/platelet-derived endothelial cell growth factor is associated with tumor angiogenesis. We evaluated the TP mRNA and protein expression in basal cell carcinomas (BCC) and in various skin tumors including numerous BCC histological simulants. Immunohistochemistry was performed on 99 paraffin sections of formalin-fixed skin tumors using monoclonal antibodies (mAb) against TP. TP mRNA levels were measured by real time RT-PCR in whole BCCs (wBCC) and laser capture microdissected (LCM) BCC tumor cells. TP immunostaining was negative in all BCC variants and in most of the benign trichogeneic tumors studied. By contrast, TP was constantly immunodetected in actinic keratosis (AK), squamous cell carcinomas (SCC), syringomatous carcinomas (SC), basosquamous carcinomas (BSC) and melanomas. TP mRNA levels were low and statistically not different in wBCC and normal skin but were strongly downregulated in LCM-BCC as compared with LCM-normal epidermis. We concluded that (i) anti-TP mAb is an useful marker to differentiate BCC from AK, SCC, BSC and SC but not from trichoblastic tumors, (ii) the lack of TP protein expression in BCC tumoral cells is linked to transcriptional regulatory mechanisms, (iii) the low TP mRNA levels in whole BCC may be related to the low intra-tumoral microvessel density, the slow growth and the very low metastatic potential of these tumors.

Practical applications for epigenetic biomarkers in cancer diagnostics

Cancer represents a major global health problem and improvement of cancer treatment requires the development of new and useful molecular diagnostic tests that enable the detection of occult tumors, direction of personalized treatments, monitoring of patients during therapeutic intervention and prediction of long-term clinical outcomes. The ideal molecular diagnostic for cancer testing will be based upon non-invasive sources of DNA and will employ biomarkers that have excellent sensitivity, specificity and overall predictive value. Numerous genes are known to be hypermethylated during cancer development and progression. These methylation-sensitive genes represent potentially valuable epigenetic biomarkers for development of practical cancer molecular diagnostics. In fact, many epigenetic biomarkers have proven to possess excellent predictive value in assays designed to detect occult (or developing) neoplasms and/or forecast clinical course/outcome. The progress to date in this emerging area of cancer diagnostics suggests that we are not far away from a time when testing for epigenetic biomarkers will represent an integral part of cancer screening protocols that can be effectively applied to the general population and/or to groups of people with defined risk factors for specific cancer types.

Association of Methylenetetrahydrofolate Reductase Polymorphism and the Risk of Squamous Cell Carcinoma in Renal Transplant Patients

The relative risk of developing cutaneous squamous cell carcinoma (SCC) is significantly increased after organ transplantation. We investigated the genetic association of SCC in two pathways associated with cancer risks, with the potential for modification by vitamin supplementation. A total of 367 renal transplant recipients (117 with SCC and 250 without any skin cancer) were genotyped for key polymorphisms in the folate pathway (methylene tetrahydrofolate reductase; MTHFR:C677T), and the vitamin D pathway (vitamin D receptor: Intron8G/T;). Individuals carrying the MTHFR 677T allele had a marked increase in risk of SCC (adjusted odds ratio=2.54, P=0.002, after adjustment for age, ender, skin type, sun exposure score, and immunosuppression duration; lower 95% confidence boundary odds ratio of 1.41). In contrast, vitamin D receptor polymorphisms were not significantly associated. Folate-sensitive pathways may play a critical role in the elevated rate of SCC in renal transplant recipients.

Epigenetic events in malignant melanoma

Irreversible changes in the DNA sequence, including chromosomal deletions or amplification, activating or inactivating mutations in genes, have been implicated in the development and progression of melanoma. However, increasing attention is being turned towards the participation of 'epigenetic' events in melanoma progression that do not affect DNA sequence, but which nevertheless may lead to stable inherited changes in gene expression. Epigenetic events including histone modifications and DNA methylation play a key role in normal development and are crucial to establishing the correct program of gene expression. In contrast, mistargeting of such epigenetic modifications can lead to aberrant patterns of gene expression and loss of anti-cancer checkpoints. Thus, to date at least 50 genes have been reported to be dysregulated in melanoma by aberrant DNA methylation and accumulating evidence also suggests that mistargetting of histone modifications and altered chromatin remodeling activities will play a key role in melanoma. This review gives an overview of the many different types of epigenetic modifications and their involvement in cancer and especially in melanoma development and progression.

Genetic factors associated with skin cancer in renal transplant patients

BACKGROUND

Non-melanoma skin cancer represents a significant cause of morbidity and mortality among renal transplant recipients. Established risk factors that increase susceptibility to skin cancer after transplantation include skin type, sun exposure and level of immunosuppression.

METHODS

A comprehensive literature review was carried out to discuss relevant genetic polymorphism for the development of skin cancer in organ transplant recipients. These include genetic polymorphisms in glutathione S-transferase, interleukin-10, retinoblastoma and p53 genes. We also discuss genetic polymorphisms in the folate pathway, melanocortin 1 receptor and vitamin D receptor recently discovered in our group.

RESULTS

No single factor is causative in cutaneous carcinogenesis in transplant recipients. Interactions of some of the above mechanisms with known environmental factors lead to increased risk.

CONCLUSION

Polymorphisms in methylenetetrahydrofolate reductase are potentially correctable with folic acid supplementation; however, further evaluation is required in adequately powered prospective clinical trials. Avoidance of known oncogenic environmental factors and genetic risk evaluation may improve outcomes in transplant patients.

Epigenetic abnormalities in cutaneous squamous cell carcinomas: frequent inactivation of the RB1/p16 and p53 pathways

BACKGROUND

Aberrant methylation of CpG islands in the promoter regions of cancer-related genes has been demonstrated in many human tumours. However, the methylation profile of these regions in cutaneous squamous cell carcinomas (SCCs) has not been well studied.

OBJECTIVES

To examine epigenetic abnormalities of a wide range of cancer-related genes in SCCs.

METHODS

We investigated the methylation status of 11 candidate cancer-related genes (CDH1, p16(INK4a), p14(ARF), DAPK1, MGMT, RB1, RASSF1, p15(INK4b), PTEN, PRDM2 and p53) in 20 cases of SCC by methylation-specific polymerase chain reaction, and comparatively examined the protein production of E-cadherin (CDH1), p16, RB1, p14, BMI1 and cyclin A by immunohistochemical analysis.

RESULTS

The frequency of cancer-related gene methylation in SCCs was: CDH1 (95%), p16 (20%), p14 (15%), DAPK1 (15%), MGMT (15%), RB1 (5%), RASSF1 (5%), p15 (0%), PTEN (0%), PRDM2 (0%) and p53 (0%). Almost all cases with hypermethylation of CDH1, p16, RB1 and p14 showed no obvious production of each protein, suggesting that promoter hypermethylation of these genes contributes to the loss of protein production. The results of methylation analysis, in combination with the results of our previous mutation analysis of CDKN2A locus and p53, revealed that 70% of SCCs have alterations in the RB1/p16 or p53 pathway.

CONCLUSIONS

Our findings indicate that the promoter hypermethylation of cancer-related genes, especially CDH1, is frequently shown in SCCs, and dysregulation of the RB1/p16 and/or p53 pathway through either genetic or epigenetic mechanisms, except for epigenetic abnormalities of p53 itself, should contribute to the carcinogenesis of SCCs.

Aberrant expression of deoxyribonucleic acid methyltransferases DNMT1, DNMT3A, and DNMT3B in women with endometriosis

OBJECTIVE

Since endometriosis is a persistent disease with substantial gene dysregulation, there must be cellular memory of some sort that constitutes a unique cell identity for endometriotic cells. Epigenetic regulation, especially through DNA methylation, is a flexible, yet stable, mechanism for maintaining such a cellular memory. The aim of this study was to determine gene expression levels of DNMT1, DNMT3A, and DNMT3B, the three genes coding for DNA methyltransferases that are responsible for methylation.

DESIGN

Cross-sectional measurements of gene expression levels of DNMT1, DNMT3A, and DNMT3B on endometriotic tissue.

SETTING

Academic.

PATIENT(S)

Seventeen patients with laparoscopically confirmed endometriosis and 8 healthy women who underwent tubal sterilization who were free of endometriosis were recruited for the study.

INTERVENTION(S)

Epithelial cells were harvested from tissue samples by laser capture microdissection and messenger RNA abundance was measured by quantitative real-time reverse transcription-polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

The expression levels of these genes in epithelial cells from 13 ectopic endometrial tissue samples, 10 eutopic endometrial tissue samples taken from women with endometriosis, and 8 normal endometrial tissue samples from women without endometriosis.

RESULT(S)

The genes DNMT1, DNMT3A, and DNMT3B were over-expressed in the ectopic endometrium as compared with normal control subjects or the eutopic endometrium of women with endometriosis, and their expression levels were correlated positively with each other.

CONCLUSION(S)

The aberrant expression of these genes suggests that aberrant methylation may be rampant in endometriosis. This also provides a strong piece of evidence that endometriosis ultimately may be an epigenetic disease.