Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword.

The evolutionary conserved Notch pathway that first developed in metazoans and that was first discovered in fruit flies (Drosophila melanogaster) governs fundamental cell fate decisions and many other cellular key processes not only in embryonic development but also during initiation, promotion, and progression of cancer. On a first look, the Notch pathway appears remarkably simple, with its key feature representing a direct connection between an extracellular signal and transcriptional output without the need of a long chain of protein intermediaries as known from many other signaling pathways. However, on a second, closer look, this obvious simplicity exerts surprising complexity. There is no doubt that the enormous scientific progress in unraveling the functional mechanisms that underlie this complexity has recently greatly increased our knowledge about the role of Notch signaling for pathogenesis and progression of many types of cancer. Moreover, these new scientific findings have shown promise in opening new avenues for cancer prevention and therapy, although this goal is still challenging. Vol. III of the second edition of the book Notch Signaling in Embryology and Cancer, entitled Notch Signaling in Cancer, summarizes important recent developments in this fast-moving and fascinating field. Here, we give an introduction to this book and a short summary of the individual chapters that are written by leading scientists, covering the latest developments in this intriguing research area.

The Impact of Notch Signaling for Carcinogenesis and Progression of Nonmelanoma Skin Cancer: Lessons Learned from Cancer Stem Cells, Tumor Angiogenesis, and Beyond.

Since many decades, nonmelanoma skin cancer (NMSCs) is the most common malignancy worldwide. Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) are the major types of NMSCs, representing approximately 70% and 25% of these neoplasias, respectively. Because of their continuously rising incidence rates, NMSCs represent a constantly increasing global challenge for healthcare, although they are in most cases nonlethal and curable (e.g., by surgery). While at present, carcinogenesis of NMSC is still not fully understood, the relevance of genetic and molecular alterations in several pathways, including evolutionary highly conserved Notch signaling, has now been shown convincingly. The Notch pathway, which was first developed during evolution in metazoans and that was first discovered in fruit flies (Drosophila melanogaster), governs cell fate decisions and many other fundamental processes that are of high relevance not only for embryonic development, but also for initiation, promotion, and progression of cancer. Choosing NMSC as a model, we give in this review a brief overview on the interaction of Notch signaling with important oncogenic and tumor suppressor pathways and on its role for several hallmarks of carcinogenesis and cancer progression, including the regulation of cancer stem cells, tumor angiogenesis, and senescence.

Crosstalk Between Vitamin D and p53 Signaling in Cancer: An Update.

It has now been convincingly shown that vitamin D and p53 signaling protect against spontaneous or carcinogen-induced malignant transformation of cells. The vitamin D receptor (VDR) and the p53/p63/p73 proteins (the p53 family hereafter) exert their effects as receptors/sensors that turn into transcriptional regulators upon stimulus. While the p53 clan, mostly in the nucleoplasm, responds to a large and still growing number of alterations in cellular homeostasis commonly referred to as stress, the nuclear VDR is transcriptionally activated after binding its naturally occurring biologically active ligand 1,25-dihydroxyvitamin D with high affinity. Interestingly, a crosstalk between vitamin D and p53 signaling has been demonstrated that occurs at different levels, has genome-wide implications, and is of high importance for many malignancies, including non-melanoma skin cancer. These interactions include the ability of p53 to upregulate skin pigmentation via POMC derivatives including alpha-MSH and ACTH. Increased pigmentation protects the skin against UV-induced DNA damage and skin photocarcinogenesis, but also inhibits cutaneous synthesis of vitamin D. A second level of interaction is characterized by binding of VDR and p53 protein, an observation that may be of relevance for the ability of 1,25-dihydroxyvitamin D to increase the survival of skin cells after UV irradiation. UV irradiation-surviving cells show significant reductions in thymine dimers in the presence of 1,25-dihydroxyvitamin D that are associated with increased nuclear p53 protein expression and significantly reduced NO products. A third level of interaction is documented by the ability of vitamin D compounds to regulate the expression of the murine double minute (MDM2) gene in dependence of the presence of wild-type p53. MDM2 has a well-established role as a key negative regulator of p53 activity. Finally, p53 and its family members have been implicated in the direct regulation of the VDR. This review gives an update on some of the implications of the crosstalk between vitamin D and p53 signaling for carcinogenesis in the skin and other tissues, focusing on a genome-wide perspective.

A Snapshot of the Molecular Biology of Notch Signaling: Challenges and Promises.

Evolutionary conserved Notch signaling is of high importance for embryogenesis and adult tissues, representing one of the most fascinating pathways that regulate key cell fate decisions and other core processes. This chapter gives a short introduction to the first volume of the book entitled Notch Signaling in Embryology and Cancer, that is intended to provide both basic scientists and clinicians who seek today`s clearest understanding of the molecular mechanisms that mediate Notch signaling with an authoritative day-to-day source. On a first look, Notch signaling, that first developed in metazoans and that was first discovered in a fruit fly, seems fallaciously simple, with its key feature being a direct link between an extracellular signal and transcriptional output without the requirement of an extended chain of protein intermediaries as needed by the majority of other signaling pathways. However, on a second, closer look, this obvious simplicity hides remarkable complexity. Notch signaling, that relies on an extensive collection of mechanisms that it exerts alongside of its core transcriptional machinery, orchestrates and governs cellular development by inducing and regulating communication between adjacent cells. In general, a cell expressing the Notch receptor can be activated in trans by ligands on an adjacent cell leading to alteration of transcription and cellular fate. However, ligands also have the ability to inhibit Notch signaling and this can be accomplished when both receptor and ligands are co-expressed in cis on the same cell. The so called non-canonical Notch pathways further diversify the potential outputs of Notch, and allow it to coordinate regulation of many aspects of cell biology. Fortunately, the generation and investigation of knockout mice and other animal models have in recent years resulted in a huge volume of new scientific informations concerning Notch gene function, allowing to dissect the role of specific Notch components for human development and health, and showing promise in opening new avenues for prevention and therapy of a broad variety of independent diseases, including cancer, although this goal is still challenging.

Notch Signaling and Tissue Patterning in Embryology: An Introduction.

The attention of science first turned to the gene that later earned the name Notch over a century ago, when the American scientist John S. Dexter discovered in his laboratory at Olivet College the characteristic notched-wing phenotype (a nick or notch in the wingtip) in mutant fruit flies Drosophila melanogaster. At present, it is generally accepted that the Notch pathway governs tissue patterning and many key cell fate decisions and other core processes during embryonic development and in adult tissues. Not surprisingly, a broad variety of independent inherited diseases (including CADASIL, Alagille, Adams-Oliver, and Hajdu-Cheney syndromes) have now convincingly been linked to defective Notch signaling. In the second edition of the book entitled Notch Signaling in Embryology and Cancer, leading researchers provide a comprehensive, highly readable overview on molecular mechanisms of Notch signaling (Volume I), and notch's roles in embryology (Vol. II) and cancer (Vol. III). In these introductory pages of Vol. II, we give a short overview on its individual chapters, which are intended to provide both basic scientists and clinicians who seek today's clearest understanding of the broad role of Notch signaling in embryology with an authoritative day-to-day source.

Notch Signaling and Embryonic Development: An Ancient Friend, Revisited.

The evolutionary highly conserved Notch pathway, which first developed during evolution in metazoans and was first discovered in fruit flies (Drosophila melanogaster), governs many core processes including cell fate decisions during embryonic development. A huge mountain of scientific evidence convincingly demonstrates that Notch signaling represents one of the most important pathways that regulate embryogenesis from sponges, roundworms, Drosophila melanogaster, and mice to humans. In this review, we give a brief introduction on how Notch orchestrates the embryonic development of several selected tissues, summarizing some of the most relevant findings in the central nervous system, skin, kidneys, liver, pancreas, inner ear, eye, skeleton, heart, and vascular system.

Notch Pathway and Inherited Diseases: Challenge and Promise.

The evolutionary highly conserved Notch pathway governs many cellular core processes including cell fate decisions. Although it is characterized by a simple molecular design, Notch signaling, which first developed in metazoans, represents one of the most important pathways that govern embryonic development. Consequently, a broad variety of independent inherited diseases linked to defective Notch signaling has now been identified, including Alagille, Adams-Oliver, and Hajdu-Cheney syndromes, CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), early-onset arteriopathy with cavitating leukodystrophy, lateral meningocele syndrome, and infantile myofibromatosis. In this review, we give a brief overview on molecular pathology and clinical findings in congenital diseases linked to the Notch pathway. Moreover, we discuss future developments in basic science and clinical practice that may emerge from recent progress in our understanding of the role of Notch in health and disease.

A snapshot of anatomy teaching: Peer-led anatomy boot camps - Priming for success?

INTRODUCTION: Pending changes regarding the medical curricula in Germany prompted us, members of the Department of Anatomy at the Medical Faculty of Saarland University, to critically evaluate anatomy teaching with special attention to macroscopic anatomy and the dissection class. Aiming at a thorough assessment we were particularly interested to which extend an optional peer-led tutorial ("anatomy boot camp"), which had preceded the dissection class, impacted the outcome in a series of oral exams of those who had participated. METHODS: We evaluated a student cohort of 307 students in the fall/winter semester 2015/16 at Saarland University, including those enrolled in medicine and dentistry, by implementing a series of questionnaires specifically designed for five mandatory oral exams during the course of the dissection class. The questionnaires contained different exam-relevant questions as well as several demographic items. The evaluation was complemented by interviews with students and examiners. RESULTS: Participants of the anatomy boot camp generally performed better in all exams and in three of them statistically significant. Items such as gender, age, and previous experiences in the health care professions contributed marginally - if at all - to the overall students' performance. Intriguingly, most students welcomed the idea of implementing questionnaire-based oral exams to balance out the different experience level of the respective examiner. CONCLUSION: Our study showed that a comparable minimal timely investment on the part of the students to choose to participate in an optional anatomy boot camp was positively correlated with students' performance.

Solarium Use and Risk for Malignant Melanoma: Meta-analysis and Evidence-based Medicine Systematic Review.

BACKGROUND: There is an ongoing debate whether solarium use (indoor tanning/artificial UV) may increase the risk for primary cutaneous malignant melanoma. AIM: A systematic literature search was conducted using MEDLINE and ISI Web of Science. Included studies were critically assessed regarding their risk of bias, and methodological shortcomings. Levels of evidence and grades of recommendation were determined according to guidelines of the Oxford Centre for Evidence-Based Medicine. Summary risk estimates and 95% confidence intervals for four different outcomes (ever exposure, exposure at younger age, high/low exposure vs. non-exposure) were derived from random-effects meta-analyses to account for possible heterogeneity across studies. RESULTS: Two cohort and twenty-nine case-control studies were eligible. Overall, quality of included studies was poor as a result of severe limitations, including possible recall and selection bias, and due to lack of interventional trials. Summary risk estimates suggested a weak association (odds ratio (OR)=1.19, 95% confidence interval (CI)=1.04-1.35, p=0.009) for ever-exposure to UV radiation from a solarium with melanoma risk. However, sensitivity analyses did not show an association for studies from Europe (OR=1.10; 95%CI=0.95-1.27, p=0.218), studies with low risk of bias (OR=1.15; 95%CI=0.94-1.41, p=0.179), and studies conducted after 1990 (OR 1.09; 95%CI=0.93-1.29, p=0.295). Moreover, moderate associations were found for first exposure to UV radiation from a solarium at younger age (<25 years) and high exposure (>10 sessions in lifetime) with melanoma risk. However, for all outcomes analyzed, overall study quality and resulting levels of evidence (3a-) and grades of recommendation (D) were low due to lack of interventional studies and severe limitations including unobserved or unrecorded confounding. CONCLUSION: Current scientific knowledge is mainly based on observational studies with poor quality data, which report associations but do not prove causality. At present, there is no convincing evidence that moderate/responsible solarium use increases melanoma risk.

Modulation of macrophage phagocytosis in vitro-A role for cholinergic stimulation?

Acetylcholine is synthetized and released from neural cells, but also by non-neuronal cells such as epithelial cells or keratinocytes. Cholinergic agonists enhance the phagocytosis of zymosan particles in primary peritoneal macrophages. The aim of this study was to investigate the effect of carbachol stimulation on phagocytosis in a macrophage cell line using microspheres. The murine cell line MH-S was used in a phagocytosis assay with fluorescent latex beads. The amount of the ingested beads was determined using flow cytometry. Gene expression was investigated using polymerase chain reaction. Gene expression of the muscarinic receptors M1, M3, M4 and M5 but not M2 was found. Carbachol slightly increased the phagocytosis of microspheres in the macrophages. A co-stimulation using lipopolysaccharide and carbachol did not increase the effect of lipopolysaccharide alone. In conclusion, cholinergic stimulation in vitro only moderately modulates the phagocytosis of microspheres. M2 might have a role in stimulation of macrophage phagocytosis.

Targeting the non-neuronal cholinergic system in macrophages for the management of infectious diseases and cancer: challenge and promise.

Macrophages represent key players of the immune system exerting highly effective defense mechanisms against microbial infections and cancer that include phagocytosis and programmed cell removal. Recent findings highlight the relevance of the non-neuronal cholinergic system for the regulation of macrophage function that opens promising new concepts for the treatment of infectious diseases and cancer. This mini review summarizes our present knowledge on this topic and gives an outlook on future developments.

Human Pigmentation, Cutaneous Vitamin D Synthesis and Evolution: Variants of Genes (SNPs) Involved in Skin Pigmentation Are Associated with 25(OH)D Serum Concentration.

Vitamin D deficiency is common and associated with higher risk for and unfavourable outcome of many diseases. Limited data exist on genetic determinants of serum 25(OH)D concentration. In a cohort of the LURIC study (n=2974, median 25(OH)D concentration 15.5 ng/ml), we tested the hypothesis that variants (SNPs, n=244) of several genes (n=15) involved in different aspects of skin pigmentation, including melanosomal biogenesis (ATP7A, DTNBP1, BLOC1S5, PLDN, PMEL), melanosomal transport within melanocytes (RAB27A, MYO5A, MLPH); or various melanocyte signaling pathways (MC1R, MITF, PAX3, SOX10, DKK1, RACK1, CNR1) are predictive of serum 25(OH)D levels. Eleven SNPs located in 6 genes were associated (p<0.05) with low or high serum 25(OH)D levels, 3 out of these 11 SNPs reached the aimed significance level after correction for multiple comparisons (FDR). In the linear regression model adjusted for sex, body mass index (BMI), year of birth and month of blood sample rs7565264 (MLPH), rs10932949 (PAX3), and rs9328451 (BLOC1S5) showed a significant association with 25(OH)D. The combined impact on variation of 25(OH)D serum levels (coefficient of determination (R(2))) for the 11 SNPs was 1.6% and for the 3 SNPs after FDR 0.3%. In Cox Regression we identified rs2292881 (MLPH) as having a significant association (advantage) with overall survival. Kaplan-Meier analysis did not show any significant impact of individual SNPs on overall survival. In conclusion, these results shed new light on the role of sunlight, skin pigmentation and vitamin D for human evolution.

Sunlight, vitamin D and malignant melanoma: an update.

Solar radiation represents an essential requirement for life, not only by spending the thermal energy for photosynthesis in plants, which provides our atmosphere with oxygen, but also by facilitating the cutaneous synthesis of vitamin D in vertebrates and many other organisms. It is well known that humans and most vertebrates have to obtain an adequate source of vitamin D, in order to develop and maintain a healthy mineralized skeleton and in order to be protected against cancer and a broad variety of other diseases. On the other hand, solar UV radiation can be assumed to be the most relevant environmental carcinogen causing melanoma and nonmelanoma skin cancer with increasing incidences. During the last decades, epidemiological studies and experimental animal models, including genetically engineered mice, the Xiphophorus hybrid fish, the south american oppossum and human skin xenografts, have further elucidated the multi-step process of UV-induced melanomagenesis. It has to be emphasized that, in contrast to intermittent, short-term high-dose solar UV-exposure, more chronic less intense exposure (which is recommended by many experts in the field to obtain a sufficient vitamin D status) has not been found to be a risk factor for the development of melanoma and in fact has been found in several studies to be protective. Interestingly, several independent lines of investigation have demonstrated convincing evidence that vitamin D and/or analogs may be effective in the prevention and treatment of melanoma. This essay summarizes our present understanding about the pathogenic role of UV radiation and of vitamin D for malignant melanoma.

Tumor suppression in skin and other tissues via cross-talk between vitamin D- and p53-signaling.

P53 and its family members have been implicated in the direct regulation of the vitamin D receptor (VDR). Vitamin D- and p53-signaling pathways have a significant impact on spontaneous or carcinogen-induced malignant transformation of cells, with VDR and p53 representing important tumor suppressors. VDR and the p53/p63/p73 proteins all function typically as receptors or sensors that turn into transcriptional regulators upon stimulus, with the main difference being that the nuclear VDR is activated as a transcription factor after binding its naturally occurring ligand 1,25-dihydroxyvitamin D with high affinity while the p53 family of transcription factors, mostly in the nucleoplasm, responds to a large number of alterations in cell homeostasis commonly referred to as stress. An increasing body of evidence now convincingly demonstrates a cross-talk between vitamin D- and p53-signaling that occurs at different levels, has genome-wide implications and that should be of high importance for many malignancies, including non-melanoma skin cancer. One interaction involves the ability of p53 to increase skin pigmentation via POMC derivatives including alpha-MSH and ACTH. Pigmentation protects the skin against UV-induced DNA damage and skin carcinogenesis, yet on the other hand reduces cutaneous synthesis of vitamin D. A second level of interaction may be through the ability of 1,25-dihydroxyvitamin D to increase the survival of skin cells after UV irradiation. UV irradiation-surviving cells show significant reductions in thymine dimers in the presence of 1,25-dihydroxyvitamin D that are associated with increased nuclear p53 protein expression, and significantly reduced NO products. A third level of interaction is documented by the ability of vitamin D compounds to regulate the expression of the murine double minute 2 (MDM2) gene in dependence of the presence of wild-type p53. MDM2 has a well-established role as a key negative regulator of p53 activity. Finally, p53 and family members have been implicated in the direct regulation of VDR. This overview summarizes some of the implications of the cross-talk between vitamin D- and p53-signaling for carcinogenesis in the skin and other tissues.

The relevance of the vitamin D endocrine system (VDES) for tumorigenesis, prevention, and treatment of non-melanoma skin cancer (NMSC): Present concepts and future perspectives.

Solar UV (UV)-B-radiation exerts both beneficial and adverse effects on human health. On the one hand, it is the most important environmental risk factor for the development of non-melanoma skin cancer [NMSC; most importantly basal (BCC) and squamous (SCC) cell carcinomas], that represent the most common malignancies in Caucasian populations. On the other hand, the human body's requirements of vitamin D are mainly achieved by UV-B-induced cutaneous photosynthesis. This dilemma represents a serious problem in many populations, for an association of vitamin D-deficiency and multiple independent diseases including various types of cancer has been convincingly demonstrated. In line with these findings, epidemiologic and laboratory investigations now indicate that vitamin D and its metabolites have a risk reducing effect for NMSC. Potential mechanisms of action include inhibition of the hedgehog signaling pathway (BCC) and modulation of p53-mediated DNA damage response (SCC). As a consequence of these new findings it can be concluded that UV-B-radiation exerts both beneficial and adverse effects on risk and prognosis of NMSC. It can be assumed that many independent factors, including frequency and dose of UV-B exposure, skin area exposed, and individual factors (such as skin type and genetic determinants of the skin`s vitamin D status and of signaling pathways that are involved in the tumorigenesis of NMSC) determine whether UV-B exposure promotes or inhibits tumorigenesis of NMSC. Moreover, these findings may help to explain many of the differential effects of UV-B radiation on risk of NMSC, including variation in the dose-dependent risk for development of SCC in situ (actinic keratosis, AK), invasive SCC, and BCC. In this review, we analyze the relevance of the vitamin D endocrine system (VDES) for tumorigenesis, prevention, and treatment of NMSC and give an overview of present concepts and future perspectives.

No evidence for induction of key components of the Notch signaling pathway (Notch-1, Jagged-1) by treatment with UV-B, 1,25(OH)(2)D(3), and/or epigenetic drugs (TSA, 5-Aza) in human keratinocytes in vitro.

Notch signaling is of high importance for growth and survival of various cell types. We now analyzed the protein expression of two key components of the Notch signaling pathway (Notch-1, Jagged-1) in spontaneously immortalized (HaCaT) and in malignant (SCL-1) human keratinocytes, using western analysis. We found that Notch-1 and its corresponding ligand Jagged-1 are expressed in both cell lines, with no marked change following UV-B treatment. Moreover, treatment of both cell lines before or after UV-B irradiation with 1,25-dihydroxyvitamin D(3), the biologically active form of vitamin D, and/or epigenetic modulating drugs (TSA; 5-Aza) did not result in a marked modulation of the protein expression of Notch-1 or Jagged-1. Under the experimental conditions of this study, treatment with 1,25(OH)(2)D(3) protected human keratinocytes in part against the antiproliferative effects of UV-B-radiation. In conclusion, our findings do not point at a differential expression of these two key components of Notch signaling in non-malignant as compared to malignant human keratinocytes, indicating that alterations in their expression are not of importance for the photocarcinogenesis of human squamous cell carcinomas. Moreover, our findings do not support the hypothesis that modulation of Notch signaling may be involved in the photoprotective effect of 1,25-dihydroxyvitamin D(3), that we and others reported previously. Additionally, we demonstrate that epigenetic modulating drugs (TSA, 5-Aza) do not markedly modulate the expression Notch-1 or Jagged-1 in UV-B-treated human keratinocytes in vitro.

Hope and challenge: the importance of ultraviolet (UV) radiation for cutaneous vitamin D synthesis and skin cancer.

Abstract Solar ultraviolet (UV)-radiation is the most important environmental risk factor for the development of non-melanoma skin cancer (most importantly basal and squamous cell carcinomas), that represent the most common malignancies in Caucasian populations. To prevent these malignancies, public health campaigns were developed to improve the awareness of the general population of the role of UV-radiation. The requirements of vitamin D is mainly achieved by UV-B-induced cutaneous photosynthesis, and the vitamin D-mediated positive effects of UV-radiation were not always adequately considered in these campaigns; a strict "no sun policy" might lead to vitamin D-deficiency. This dilemma represents a serious problem in many populations, for an association of vitamin D-deficiency and multiple independent diseases has been convincingly demonstrated. It is crucial that guidelines for UV-exposure (e.g. in skin cancer prevention campaigns) consider these facts and give recommendations how to prevent vitamin D-deficiency. In this review, we analyze the present literature to help developing well-balanced guidelines on UV-protection that ensure an adequate vitamin D-status without increasing the risk to develop UV-induced skin cancer.

Notch-signaling and nonmelanoma skin cancer: an ancient friend, revisited.

In humans and other species, Notch-signaling is of critical importance for carcinogenesis in several organs, including the skin. Interestingly, Notch-signaling appears to exert opposite roles in skin carcinogenesis as compared to carcinogenesis in other tissues. While the Notch1 receptor (Notch1) acts as a proto-oncogene in most tissues, it has been shown that Notch1 deletion in epidermal keratinocytes causes skin carcinogenesis. Recent results indicate that loss of Notch1 is not involved in the initiating event of multistage skin carcinogenesis, but acts as a skin cancer-promoting event. Moreover, recent findings underline the importance of multiple other factors, including the microenvironment, for Notch signaling in skin carcinogenesis. It can be speculated that pharmacologic modulation of Notch signaling may be an interesting target for the prevention and therapy of skin cancer.

Association of genetic variants of the vitamin D receptor (VDR) with cutaneous squamous cell carcinomas (SCC) and basal cell carcinomas (BCC): a pilot study in a German population.

BACKGROUND: Vitamin D receptor (VDR) polymorphisms have important implications for vitamin D signalling and are associated with various malignancies. PATIENTS AND METHODS: In a German population, the frequency of several VDR polymorphisms (Apa1, Taq1, Bgl1) in basal cell carcinomas (BCCs, n=90) and cutaneous squamous cell carcinomas (SCCs, n=100) as compared to healthy controls (n=51) was analyzed. RESULTS: Impressive variations in the frequency of some VDR genotypes were found when comparing skin of cancer patients and controls. An association of the genotype AaTtBb with BCC risk was found (BCC: 45.7%, SCC: 39.8% and controls: 38.0%). The genotype aaTTBB was exclusively found in the control group (20%), which suggested that this genotype may be protective against skin carcinogenesis. Moreover, the aaTTbb genotype was associated with skin cancer risk, being found at a much higher frequency in BCCs (21%) and SCCs (17%) as compared to controls (8.0%). Comparison of the frequencies of the VDR genotypes in sunlight-exposed vs. not sunlight-exposed skin areas revealed BB 30.1% vs. 7.1% respectively in BCCs and BB 28.1% vs. 0.0% respectively in SCCs, indicating that vitamin D signalling may be of importance for photocarcinogenesis of the skin. Associations also indicated that the Apa1 and Taq1 genotypes may be of importance for photocarcinogenesis of BCCs, but not for SCCs. Comparison of the VDR genotype frequencies by age (younger than 60 years vs. 60 years or older) revealed no evidence of age-dependent variations in patients with BCCs or SCCs. CONCLUSION: VDR polymorphisms are of importance for the development of BCCs and cutaneous SCCs, but further explorations of these findings and their implications are required.

Signature of VDR miRNAs and epigenetic modulation of vitamin D signaling in melanoma cell lines.

BACKGROUND: Melanoma cells express the nuclear vitamin D receptor (VDR), indicating that malignant melanoma represents a promising target for treatment with 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D(3)) or its analogs. We previously showed that some melanoma cell lines are resistant to the antiproliferative effects of 1,25(OH)(2)D(3) and that 1,25(OH)(2)D(3)-sensitivity can, at least in part, be restored by co-treatment with the histone deacetylase inhibitor (HDACI) Trichostatin A (TSA) or with the DNA methyltransferase inhibitor (DNMTI), 5-azacytidine (5-Aza). This study aimed at gaining further insights into the molecular mechanisms that underlie the epigenetic modulation of 1,25(OH)(2)D(3)-sensitivity in melanoma cells. MATERIALS AND METHODS: The expression of VDR mRNA, protein and two candidates of VDR microRNAs (miR-125b, miR-27b) were compared in 1,25(OH)(2)D(3)-responsive (MeWo, SK-Mel28) and -resistant (SK-Mel5, IGR) melanoma cell lines and in normal human melanocytes (NHM) using real time PCR and western blot analysis. Additionally, the effect of 1,25(OH)(2)D(3), epigenetic modulating drugs (TSA, 5-Aza) and miR-125b antisense on the expression of VDR messenger RNA (mRNA)/protein, miR-125b and miR-27b was investigated. RESULTS: Treatment with 1,25(OH)(2)D(3) and/or epigenetic drugs (5-Aza, TSA) modulated the VDR mRNA expression in the 1,25(OH)(2)D(3)-responsive and - resistant melanoma cell lines and in the NHM. Treatment with 5-Aza, but not with TSA, reduced the expression of miR-125b in the 1,25(OH)(2)D(3)-responsive and -resistant melanoma cell lines and in the NHM. Treatment with 1,25(OH)(2)D(3) and/or epigenetic drugs (5-Aza, TSA) reduced the miR-27b expression in three out of four melanoma cell lines. Moreover, no difference was observed in VDR protein expression in the 1,25(OH)(2)D(3)-responsive as compared to the 1,25(OH)(2)D(3)-resistant melanoma cell lines. Transfection with miR-125b antisense did not affect the VDR mRNA/protein expression in the IGR cells. CONCLUSION: Responsiveness to 1,25(OH)(2)D(3) corresponds to the expression level of VDR mRNA which in turn might be regulated by VDR microRNAs or epigenetic modulating drugs.