Differentiation of murine melanocyte precursors induced by 1,25-dihydroxyvitamin D3 is associated with the stimulation of endothelin B receptor expression

The correlation analysis between alterations of serum vitamin D, IL-33 levels, and clinical improvement after narrow-band UVB treatment in vitiligo patients: A case-control study

BACKGROUND

The etiology of vitiligo has not been completely elucidated. Recently, 25-hydroxyvitamin D (25(OH)D) and IL-33 levels were found to be associated with the development of the vitiligo. The aim was to assess relationship between 25(OH)D, IL-33 levels, and clinical improvement after narrow-band UVB treatment in vitiligo.

METHOD

Patients with vitiligo who underwent at least 48 sessions of narrow-band UVB treatment were included in this study. Age, gender, smoking status, family history of vitiligo, type of vitiligo, body surface area affected by vitiligo, and vitiligo activity were recorded. 25(OH)D and IL-33 were measured and compared at baseline, second month, and fourth month.

RESULTS

Twenty patients with vitiligo and 20 healthy controls were included in this study. The mean baseline 25(OH)D level of vitiligo group was statistically significantly lower than the control group's (p < .05). The mean baseline IL-33 level was higher in vitiligo group with no statistically significantly difference (p > .05). The increase in 25(OH)D level and the decrease in vitiligo-affected body surface area were found to be statistically significant during treatment (p < .05). The mean IL-33 levels were found to be lower at the second and fourth month compared to baseline. However, there were no statistical significance (p > .05).

CONCLUSION

Low levels of 25(OH)D are thought to play a role in the etiopathogenesis of vitiligo. 25(OH)D increase due to phototherapy may have a role in repigmentation independently from the direct effect of narrow-band UVB.

Impact of narrow-band ultraviolet B radiation therapy on the quality of life of patients with vitiligo

Objectives

Patients with vitiligo experience emotional and psychological stress as they undergo long-term therapy. The debilitating psychosocial effects of this disease on patients' quality of life is well-documented. This study evaluates the effect of the introduction of narrow-band ultraviolet-B (NB-UVB) therapy on the quality of life of patients with vitiligo in Almadinah Almunawwarah, KSA.

Methods

Thirty-eight patients from the main dermatology center of Ohud Hospital, Almadinah Almunawwarah, were interviewed between June 2017 and March 2019 using the Dermatology Life Quality Index (DLQI) questionnaire. The interviews were conducted before and one year after the course of NB-UVB therapy, which was added as a new treatment modality to the basic therapeutic regimen of topical medications.

Results

The patients' response to vitiligo therapy was positive. The overall patient satisfaction score regarding the NB-UVB therapy was as high as 9.1 out of 10. The initial overall DLQI score (5.67 ± 0.90) markedly decreased after the NB-UVB therapy (3.08 ± 0.56), indicating a significant improvement. The patients' adherence to the follow-up visits also improved.

Conclusion

NB-UVB therapy is effective in alleviating psychological stress and improving the quality of life of patients with vitiligo.

Vitamin D: Skin, sunshine, and beyond

Vitamin D is a steroid hormone of importance to the field of dermatology. Skin is unique in that it is the site of vitamin D synthesis upon sun exposure and a target organ for its activity. We explore the physiology and metabolic mechanism of action of vitamin D, as well as its effects on the skin. We also discuss the current evidence of the efficacy and safety of oral and topical vitamin D analogues on skin conditions such as psoriasis, atopic dermatitis, vitiligo, sunburn, actinic keratosis, and fibrosing skin disorders. Based on currently available scientific evidence, the National Academy of Medicine's recommended dietary allowance for vitamin D ranges from 400 IU to 800 IU daily based on age categories.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Association Between Parkinson's Disease and Melanoma: Putting the Pieces Together

Patients with Parkinson’s disease (PD) generally have reduced risk of developing many types of cancers, except melanoma—a malignant tumor of melanin-producing cells in the skin. For decades, a large number of epidemiological studies have reported that the occurrence of melanoma is higher than expected among subjects with PD, and the occurrence of PD is reciprocally higher than expected among patients with melanoma. More recent epidemiological studies further indicated a bidirectional association, not only in the patients themselves but also in their relatives. This association between PD and melanoma offers a unique opportunity to understand PD. Here, we summarize epidemiological, clinical, and biological evidence in regard to shared risk factors and possible underlying mechanisms for these two seemingly distinct conditions.

Assessment of Serum Vitamin D Levels in Patients with Vitiligo in Jordan: A Case-Control Study

Background

Low vitamin D serum levels have been associated with many autoimmune disorders and several other skin diseases. Vitiligo is an autoimmune disease characterized by destruction of melanocytes by immune mechanisms. Melanocytes express vitamin D receptors, and their function can be affected by vitamin D status.

Objectives

The main objective of this study is to compare vitamin D levels in patients with vitiligo vs normal population and whether vitamin D deficiency is associated with vitiligo.

Methods

A case-control study was conducted. 100 vitiligo patients and 100 as controls were included in this study. Serum vitamin D level was measured for both vitiligo patients and controls, results were compared, and statistical analysis was done to compare the results.

Results

The median age of vitiligo cases was 23 years (ranges, 2–80). 58% of vitiligo patients were females. The median vitamin D level was not significantly different between the two groups (vitiligo = 14.1 (IQR 9.9–20.4) vs control = 16.5 (IQR 10.3–25.3) (P=0.28)). Most vitiligo cases and controls were found to have low levels of vitamin D (either insufficient 20–30 ng/mL or low <20 ng/mL).

Conclusions

There was no significant difference in vitamin D levels in vitiligo patients compared to controls. However, vitamin D levels were generally low in both groups.

Evidence of a possible therapeutic role of vitamin D in a cohort of adult Caucasian vitiligo patients

Reduced serum 25(OH)D levels have been largely reported in vitiligo, which is an autoimmune skin disorder characterized by the appearance of achromic macules. Since vitamin D can positively modulate immune function and stimulate melanogenesis in vitro, a possible role of sufficient vitamin D levels in promoting the stability of the disease and repigmentation process might be hypothesized in vitiligo. Hence, we conducted an observational study on medical records related to 101 vitiligo patients, in order to correlate baseline 25(OH)D levels with the baseline vitiligo activity and repigmentation of vitiligo macules on a 6-month follow-up. According to our results, at baseline we found that active vitiligo was significantly associated with 25(OH)D deficiency (≤20 ng/mL) (P = 0.036) or insufficiency (21-29 ng/mL) (P = 0.041), while stable disease was significantly associated with sufficient 25(OH)D levels (30-100 ng/mL) (P = 0.043). After 6 months, vitiligo patients with sufficient 25(OH)D levels (30-100 ng/mL) achieved a significantly higher degree of repigmentation. In conclusion, our study provides a novel evidence of a significant positive association of sufficient 25(OH)D levels with the stability of the disease and a satisfactory repigmentation process in Caucasian adult vitiligo patients and strengthen the need to assess vitamin D status in vitiligo. The correlation between sufficient vitamin D levels and a satisfactory course of the disease opens the way for future randomized controlled trials assessing a possible beneficial role of vitamin D supplementation on vitiligo.

Vitamin D protects human melanocytes against oxidative damage by activation of Wnt/β-catenin signaling

Vitamin D analogs have been widely utilized for the treatment of vitiligo, but the molecular mechanism underlying their pharmacological effects (especially their antioxidant properties) has not yet been investigated. We evaluated the relationship between serum vitamin D level and oxidative damage severity in vitiligo patients, and investigated the molecular mechanism of vitamin D in protecting melanocytes against oxidative stress. Serum levels of 25-hydroxyvitamin D and malondialdehyde (MDA) were first measured in patients. A variety of in vitro experiments such as intracellular reactive oxygen species (ROS), cellular viability, migration, and apoptotic assays were then performed to detect the effects of vitamin D or β-catenin silencing on H₂O₂-treated melanocytes. Expression of Wnt/β-catenin, Nrf2, apoptotic, and MITF pathways was finally examined using quantitative real-time PCR and western blot. In this study, we initially found that vitamin D insufficiency was closely associated with the severity of oxidative stress in vitiligo patients. Using ex vivo cell models, we further showed that vitamin D positively modulated β-catenin signaling at both translational and posttranslational levels in melanocytes under oxidative stress. Like WNT agonists, vitamin D significantly inhibited ROS accumulation and cell apoptosis in H₂O₂-treated melanocytes and promoted their proliferative and migratory activity, while the protective effects of vitamin D against oxidative stress were abolished by β-catenin silencing in melanocytes. Furthermore, β-catenin deficiency also blocked the activation of Nrf2 and MITF as well as the inhibition of apoptosis induced by vitamin D. Taken together, vitamin D insufficiency was associated with severity of oxidative stress in vitiligo patients. Our work also provides new insights into the mechanism of vitamin D against vitiligo, in which vitamin D protects melanocytes against oxidative stress by activating Wnt/β-catenin signaling.

Vitamin D receptor gene polymorphism, serum 25-hydroxyvitamin D levels, and risk of vitiligo: A meta-analysis

OBJECTIVES

To explore the relationship among the vitamin D receptor (VDR) gene polymorphisms, serum 25-hydroxyvitamin D levels, and vitiligo.

METHODS

Databases including PubMed, Cochrane Library, Ovid, Web of Science, CNKI, SinoMed, and Wanfang Data were systematically searched. The association was assessed using odds ratios (ORs), standard mean difference (SMD), and 95% confidence intervals (CIs). The statistical tests were performed using Review Manager 5.3.3.

RESULTS

We identified a total of 17 studies. The relationship between VDR gene polymorphisms (BsmI, ApaI, TaqI, and FokI), serum 25 (OH)D levels, and incidence of vitiligo was investigated. The results of this meta-analysis showed that the dominant genetic model (CC+AC vs AA, P = .007, OR = 1.41, 95% CI = 1.10-1.80), recessive genetic model (CC vs AC+AA, P = .01, OR = 4.10, 95% CI = 1.36-12.35), and allelic contrast model (C vs A, P = .005, OR = 1.87, 95% CI = 1.21-2.90) of VDR Apal locus increased the risk of vitiligo, and BsmI, TaqI, and FokI loci and the risk of vitiligo have no obvious correlation. Serum 25 (OH)D deficiency was positively associated with the incidence of vitiligo (P < .0001, SMD = -0.94, 95% CI = -1.39, -0.48).

CONCLUSION

This meta-analysis revealed that VDR Apal polymorphism increased the susceptibility risk of vitiligo, and there is a positive correlation between serum 25 (OH)D deficiency and the incidence of vitiligo.

The convergence theory for vitiligo: A reappraisal

Vitiligo is characterized by progressive loss of skin pigmentation. The search for aetiologic factors has led to the biochemical, the neurologic and the autoimmune theory. The convergence theory was then proposed several years ago to incorporate existing theories of vitiligo development into a single overview of vitiligo aetiology. The viewpoint that vitiligo is not caused only by predisposing mutations, or only by melanocytes responding to chemical/radiation exposure, or only by hyperreactive T cells, but rather results from a combination of aetiologic factors that impact melanocyte viability, has certainly stood the test of time. New findings have since informed the description of progressive depigmentation. Understanding the relative importance of such aetiologic factors combined with a careful selection of the most targetable pathways will continue to drive the next phase in vitiligo research: the development of effective therapeutics. In that arena, it is likewise important to acknowledge that pathways affected in some patients may not be altered in others. Taken together, the convergence theory continues to provide a comprehensive viewpoint of vitiligo aetiology. The theory serves to intertwine aetiologic pathways and will help to define pathways amenable to disease intervention in individual patients.

Vitamin D signaling and melanoma: role of vitamin D and its receptors in melanoma progression and management

Ultraviolet B (UVB), in addition to having carcinogenic activity, is required for the production of vitamin D3 (D3) in the skin which supplies >90% of the body's requirement. Vitamin D is activated through hydroxylation by 25-hydroxylases (CYP2R1 or CYP27A1) and 1α-hydroxylase (CYP27B1) to produce 1,25(OH)₂D3, or through the action of CYP11A1 to produce mono-di- and trihydroxy-D3 products that can be further modified by CYP27B1, CYP27A1, and CYP24A1. The active forms of D3, in addition to regulating calcium metabolism, exert pleiotropic activities, which include anticarcinogenic and anti-melanoma effects in experimental models, with photoprotection against UVB-induced damage. These diverse effects are mediated through an interaction with the vitamin D receptor (VDR) and/or as most recently demonstrated through action on retinoic acid orphan receptors (ROR)α and RORγ. With respect to melanoma, low levels of 25(OH)D are associated with thicker tumors and reduced patient survival. Furthermore, single-nucleotide polymorphisms of VDR and the vitamin D-binding protein (VDP) genes affect melanomagenesis or disease outcome. Clinicopathological analyses have shown positive correlation between low or undetectable expression of VDR and/or CYP27B1 in melanoma with tumor progression and shorter overall (OS) and disease-free survival (DFS) times. Paradoxically, this correlation was reversed for CYP24A1 (inactivating 24-hydroxylase), indicating that this enzyme, while inactivating 1,25(OH)₂D3, can activate other forms of D3 that are products of the non-canonical pathway initiated by CYP11A1. An inverse correlation has been found between the levels of RORα and RORγ expression and melanoma progression and disease outcome. Therefore, we propose that defects in vitamin D signaling including D3 activation/inactivation, and the expression and activity of the corresponding receptors, affect melanoma progression and the outcome of the disease. The existence of multiple bioactive forms of D3 and alternative receptors affecting the behavior of melanoma should be taken into consideration when applying vitamin D management for melanoma therapy.

Development of Asymmetric Facial Depigmentation in a Patient Treated with Dasatinib with New-Onset Hypovitaminosis D: Case Report and Review of the Literature

Dasatinib is a second-generation tyrosine kinase inhibitor (TKI) used to treat imatinib-resistant chronic myelogenous leukemia (CML), as well as other Philadelphia chromosome-positive lymphoproliferative disorders. While the most commonly reported cutaneous side effects with this therapy include a morbilliform eruption, skin exfoliation, and skin irritation, pigmentary abnormalities have also been observed, albeit much more rarely. We present the case of a 72-year-old South Asian male with CML who presented with new-onset hypopigmentation of his face and scalp three years after a dose increase of dasatinib therapy, in the setting of newly discovered borderline hypovitaminosis D. Dasatinib and the other TKIs are believed to induce dyschromias via modulation of the c-kit receptor and its associated signaling pathway, which is involved in melanocyte survival, proliferation, and migration.

Vitamin D Receptor Expression in Vitiligo

Background:

Vitiligo is a progressive depigmenting disorder characterized by loss of functional melanocytes from the epidermis. The etiopathogenesis of vitiligo is still unclear. Vitamin D has stimulatory effects on melanocytes and acts through its nuclear Vitamin D receptor (VDR) on target cells.

Aims and Objectives:

The purpose of this study was to declare the role of Vitamin D in the pathogenesis of vitiligo.

Materials and Methods:

This case-control study included 30 vitiligo patients and 30 age, gender-matched healthy controls. Blood samples were withdrawn from the study subjects, and the serum 25(OH) D level was determined by an enzyme-linked immunosorbent assay technique. Serum 25(OH) D levels were divided into: Normal or sufficient (≥30 ng/ml), insufficient (< 30-> 20ng/ml), and deficient (≤20 ng/ml) levels. Skin biopsies were obtained from the depigmented lesions and clinically normal skin of vitiligo patients and from the controls, and VDR gene expression was determined using real-time polymerase chain reaction.

Results:

Only 10 patients with vitiligo (33.3%) had sufficient serum 25(OH) D levels (≥30 ng/ml), 12 patients (40%) had insufficient levels, and 8 patients (26.7%) had deficient levels. On the other hand, most of the controls (96.7%) had sufficient levels. The mean serum 25(OH) D level in patients was significantly decreased compared to controls (P < 0.001). The VDR-mRNA expression was also significantly decreased in lesional and nonlesional skin of patients compared to controls (P < 0.001, P < 0.001, respectively).

Conclusion:

Vitamin D deficiency influences the extent of vitiligo and could contribute to the pathogenesis of vitiligo through its immunomodulatory role and its role in melanogenesis.

Pilot study on the bioactivity of vitamin d in the skin after oral supplementation

Laboratory studies suggest that vitamin D (VD) supplementation inhibits skin carcinogenesis. However, epidemiologic studies report mixed findings in the association between circulating VD levels and skin cancer risk. We conducted a clinical study to determine whether oral cholecalciferol supplementation would exert direct bioactivity in human skin through modulation of the VD receptor (VDR). We enrolled 25 individuals with serum 25-hydroxyvitamin-D levels <30 ng/mL and with skin photodamage to take 50,000 IU of cholecalciferol biweekly for 8 to 9 weeks. Then, we obtained baseline and end-of-study skin biopsies from photodamaged (PD) and photoprotected (PP) skin, and from benign nevi (BN) and tested for mRNA expression of VDR and cytochrome P450-24 (CYP24), and markers of keratinocytic differentiation. High-dose cholecalciferol supplementation significantly elevated circulating levels of 25-hydroxyvitamin-D (P < 0.0001) and 1,25-dihydroxyvitamin-D (P < 0.0001). VDR expression in PD- and PP-skin showed minimum changes after supplementation. CYP24 expression in PD- and PP-skin was increased after supplementation by 186%, P = 0.08, and 134%, P = 0.07, respectively. In BNs from 11 participants, a trend for higher VDR and CYP24 expression was observed (average of 20%, P = 0.08, and 544%, P = 0.09, respectively). Caspase-14 expression at the basal layer in PD skin samples was the only epidermal differentiation marker that was significantly increased (49%, P < 0.0001). High-dose cholecalciferol supplementation raised serum VD metabolite levels concurrently with CYP24 mRNA and caspase-14 levels in the skin. Our findings of significant variability in the range of VDR and CYP24 expression across study samples represent an important consideration in studies evaluating the role of VD as a skin cancer chemopreventive agent.

Correlation of Vitamin D Levels with Pigmentation in Vitiligo Patients Treated with NBUVB Therapy

Cholecalciferol (vitamin D) might play a physiological role in photo-induced melanogenesis in human skin. We estimated the levels of 25-hydroxy vitamin D [25(OH)D] before, during, and after Narrow Band Ultraviolet B (NBUVB) radiation in patients of vitiligo and their correlation with NBUVB induced pigmentation. Thirty patients of vitiligo and equal number of age and sex matched controls were recruited for the study. Vitiligo patients were treated with NBUVB thrice weekly for 12 weeks. [25(OH)D] levels and Vitiligo Area and Severity Index (VASI) were calculated at 0 (baseline), 6, and 12 weeks. Baseline [25(OH)D] levels were measured in controls. Significant reduction in VASI score was observed after 12 weeks of therapy. Comparison and correlation between mean improvement in VASI and [25(OH)D] levels at 12 weeks showed moderate correlation, and the results were statistically insignificant. Mean reduction in VASI and increase in [25(OH)D] levels after 12 weeks of NBUVB showed moderate correlation. Thus, vitamin D might play a significant role in photo-induced melanogenesis. However, there might be additional effects of the phototherapy on melanogenesis. The complete mechanism of NBUVB induced pigmentation in vitiligo needs to be elucidated.

Optimization of the method for the culture of melanocyte precursors from hair follicles and their activation by 1,25-dihydroxyvitamin D3

The melanocytes in vitiligo repigmentation are derived predominantly from melanocyte precursors (MPs) present in the outer root sheath (ORS) of hair follicles. The methods currently used for culturing MPs are unstable, and the cultured cells have the capacity to produce melanin. These factors are problematic when conducting in vitro studies to investigate the mechanism of repigmentation. Although 1,25-dihydroxyvitamin D3 (VID) has been demonstrated to be highly effective in the treatment of vitiligo in the clinic, its precise mode of action has yet to be elucidated. In the present study, the method for the culture of MPs from the ORS of hair follicles was optimized and the ability of VID to activate MPs was investigated. The results suggested that the MPs cultured using the optimized method mainly exhibited bipolar morphology. The cells proliferated well and were negative for 3,4-dihydroxy-L-phenylalanine (DOPA) staining. Transmission electron microscopy revealed that the cytoplasm of the MPs contained numerous stage I and stage II melanosomes; however, stage III and IV melanosomes were not observed. Following VID treatment, the MPs showed increased dendritic morphology, the cells stained positive for DOPA and stage III and IV melanosomes appeared in the cells. Western blotting revealed that microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1) and TRP-2 were expressed in the MPs and that VID increased the expression levels of MITF, TYR and TRP-1. However, the levels of MITF, TYR and TRP-1 in the MPs prior to and following VID treatment were significantly lower compared with those in cultured epidermal melanocytes, while the levels of TRP-2 in these three groups were not significantly different. Subsequent to VID treatment, the TYR activity in the MPs increased significantly, as did the corresponding melanin levels. In conclusion, the present study successfully optimized the method for MP culture. The MPs demonstrated no significant TYR activity or melanin synthesis; therefore, the MP cultures exhibited the features of MPs in vivo. In addition, VID significantly promoted the differentiation of MPs.

Vitamin D in cutaneous carcinogenesis: part II

The role of vitamin D in health maintenance and disease prevention in fields ranging from bone metabolism to cancer is currently under intensive investigation. A number of epidemiologic studies have suggested that vitamin D may have a protective effect on cancer risk and cancer-associated mortality. With regard to skin cancer, epidemiologic and laboratory studies suggest that vitamin D and its metabolites may have a similar risk reducing effect. Potential mechanisms of action include inhibition of the hedgehog signaling pathway and upregulation of nucleotide excision repair enzymes. The key factor complicating the association between vitamin D and skin cancer is ultraviolet B radiation. The same spectrum of ultraviolet B radiation that catalyzes the production of vitamin D in the skin also causes DNA damage that can lead to epidermal malignancies. Part II of this continuing medical education article will summarize the literature on vitamin D and skin cancer to identify evidence-based optimal serum levels of vitamin D and to recommend ways of achieving those levels while minimizing the risk of skin cancer.

New vitamin D analogs as potential therapeutics in melanoma

Extensive evidence shows that the active form of vitamin D3--1α,25-dihydroxyvitamin D3--plays an important role in cancer prevention, has tumorostatic activity and may potentially be used in therapy for melanoma. Vitamin D3 and its analogs (secosteroids) exert multiple effects on cancer cells, including inhibition of cell growth and induction of differentiation. Activity of secosteroids depends on multiple cellular factors, including expression of the vitamin D receptor. Despite its endogenous origin, the key drawback for the use of pharmacologically effective doses of 1α,25-dihydroxyvitamin D3 is its hypercalcemic effect leading to profound toxicity. The solution may lie in properties of vitamin D3 analogs with modified side chains, which demonstrate low calcemic activity but conserve the anti-tumor properties. Noncalcemic vitamin D compounds were found to be potent in multiple studies that mandate further clinical testing. Finally, recent studies revealed alternative metabolic pathways for secosteroids and new targets in the cells, which opens up new therapeutic possibilities.

Off-target effects of BCR-ABL1 inhibitors and their potential long-term implications in patients with chronic myeloid leukemia

In patients with chronic myeloid leukemia (CML), use of the BCR-ABL1-specific tyrosine kinase inhibitors (TKIs) imatinib, nilotinib and dasatinib has greatly improved patient survival and prolonged disease remission. More than 10 years of data from imatinib clinical studies and many years of data for nilotinib and dasatinib have demonstrated that these TKIs are well tolerated in most patients with CML. However, these inhibitors are not entirely BCR-ABL1-specific, and this lack of specificity could account for the off-target effects of these drugs. Adverse events (AEs) are off-target effects that are detrimental to the patient. The underlying mechanisms that contribute to these effects are poorly understood and the long-term consequences of chronic TKI therapy remain largely unknown, particularly with the newer agents. Here, we review the preclinical and clinical data for several of the more frequent AEs associated with TKIs and discuss the therapeutic relevance of these AEs for patients with CML.

Double-blind, placebo-controlled, randomized study comparing 0.0003% calcitriol with 0.1% tacrolimus ointments for the treatment of endemic pityriasis alba

Background. Pityriasis alba (PA) is a frequent cause of consultation in tropical areas due to its chronic course, frequent relapses, and notorious hypopigmented lesions in pediatric dark skin populations. Currently, no treatment is widely accepted. Objective. To assess the efficacy of 0.0003% calcitriol and 0.1% tacrolimus ointments compared with placebo in the treatment of endemic PA. Methods. Twenty-eight children aged 3–17 years with 56 symmetrical lesions and phototype IV-V, were randomly assigned to receive the treatments on target lesions on the face. Improvement was evaluated at baseline and 8 weeks later clinically and by digital quantification of the affected area, colorimetry, and transepidermal water loss (TEWL). Results. Tacrolimus and calcitriol ointments induced a mean improvement of 68%, compared to 44% of placebo. We found an elevated TEWL in PA lesions. In the treated plaques, the reduction of the affected area was associated with improvement of pigmentation and TEWL. Conclusions. Calcitriol and tacrolimus induced similar repigmentation in endemic PA lesions. Melanogenic, anti-inflammatory, and barrier defect restoration properties of these drugs may explain these findings.

Melanotic neuroectodermal tumour of infancy

Melanotic neuroectodermal tumour of infancy is an extremely rare neoplasm arising in newborns and young children, typically involving the face or cranium. A case arising from the maxilla, requiring extensive resection with a near-total maxillectomy, is presented. A thorough review of the literature on this unusual tumour is provided, with emphasis on prognostic factors and appropriate treatment.

The potential role of vitamin D in the progression of benign and malignant melanocytic neoplasms

Hormonally active vitamin D3, 1,25-(OH)2D3, is believed to have a role in the prevention of cancer formation and in limiting the aggressiveness of cancers that do arise. Therefore,much interest is presently being focused on 1,25-(OH)2D3 and its analogues as potential treatments for various cancers including melanoma. This article discusses the evidence in favour of a role for 1,25-(OH)2D3 in protection against the progression of melanocytic lesions and also summarizes the mechanisms by which 1,25-(OH)2D3 may act to protect against melanoma development and progression.

PPAR-gamma agonist, ciglitazone, increases pigmentation and migration of human melanocytes

Peroxisome proliferator-activated receptors (PPARs) play an important role in cellular responses. It was reported that three subtypes of PPAR are expressed in human melanocytes. In this study, we investigated the effects of the PPAR-gamma agonist, ciglitazone, on pigmentation and migration of human melanocytes. Ciglitazone stimulated the melanin content of cells and cultured skin. This increase in pigmentation was due to the stimulation of tyrosinase activity and expression of tyrosinase and microphthalmia-associated transcription factor protein of the melanocytes. Migration was increased after ciglitazone treatment, which was observed by the Boyden chamber checkerboard analysis and a scratch motility assay. These results suggest the regulatory role of PPAR-gamma in pigmentation and migration of human melanocytes.

Establishment of a Kit-negative cell line of melanocyte precursors from mouse neural crest cells

We previously established a mouse neural crest cell line named NCCmelb4, which is positive for Kit and negative for tyrosinase. NCCmelb4 cells were useful to study the effects of extrinsic factors such as retinoic acids and vitamin D(3) on melanocyte differentiation, but in order to study the development of melanocytes from multipotent neural crest cells, cell lines of melanocyte progenitors in earlier developmental stages are needed. In the present study, we established an immortal cell line named NCCmelb4M5 that was derived from NCCmelb4 cells. NCCmelb4M5 cells do not express Kit and are immortal and stable in the absence of Kit ligand. They are positive for melanocyte markers such as tyrosinase-related protein 1 and DOPAchrome tautomerase and they contain stage I melanosomes. Interestingly, glial fibrillary acidic protein, which is a marker for glial cells, is also positive in NCCmelb4M5 cells, while NCCmelb4 cells are negative for this protein. Immunostaining and a cell ELISA assay revealed that 12-O-tetradecanoylphorbol 13-acetate (TPA) and cholera toxin (CT) induce Kit expression in NCCmelb4M5 cells. Real-time polymerase chain reaction analysis also demonstrated the induction of Kit mRNA by TPA and CT. Microphthalmia-associated transcription factor mRNA is simultaneously enhanced by the same treatment. Kit induced by TPA/CT in NCCmelb4M5 cells disappeared after the cells were subcultured and incubated without TPA/CT. These findings show that NCCmelb4M5 cells have the potential to differentiate into Kit-positive melanocyte precursors and may be useful to study mechanisms of development and differentiation of melanocytes in mouse neural crest cells.

Establishment and characterization of new cell lines derived from melanotic neuroectodermal tumor of infancy arising in the mandible

Three cell systems (MINT1/2/3) derived from a melanotic neuroectodermal tumor of infancy (MNTI) arising in the mandible of a 1-month-old newborn boy have been established, and their cytological natures have been characterized. The cells had immunopositivities for pan-keratin, vimentin, neuron-specific enolase, S-100 protein and melanoma-associated antigen (HMB-45). These immunohistochemical phenotypes were basically the same as those observed in tissue sections, in which, synaptophysin, myelin basic protein, c-myc gene products, carcinoembryonic antigen, and epithelial membrane antigen were also immunolocalized in tumor cells. Karyotyping analyzes revealed that the chromosome numbers of the three cell systems ranged from 60 to 67 with 3n ploidies, and that there were many structural aberrations, such as del(11)(q13), del(22)(q13), add(2)(p11), add(7)(q22), extra copies for chromosomes 1, 2, 3, 5, 7, 9, 10, 11, 12, 16, 20, and 22, der(9)t(9;13)(p13;q12)add(9)(q34), and der(13;21)(q10;q10), which were shared by the three cell systems, while der(19)t(11;19)(q13;p13) was found in MINT1 and MINT3. When stimulated by endothelin-3 and vitamin D(3), the cells had spinous cell shapes with immunopositivities for HMB-45, neurofilament protein and glial fibrillary acidic protein, which indicated more neural differentiation. The established cell systems will be useful for further investigation on the molecular and genetic basis of MNTI to understand its pathogenesis, which is largely unknown.

Bcl-2 Reduced and Fas Activated by the Inhibition of Stem Cell Factor/KIT Signaling in Murine Melanocyte Precursors

Stem cell factor (SCF) and its receptor, KIT, are essential to the migration and differentiation of melanocytes during embryogenesis. We previously demonstrated that apoptosis is induced by blocking survival function of the SCF/KIT interaction in a mouse neural crest cell (NCC) primary culture. Using the NCCmelb4 cell line, we investigated the occurrence of apoptosis in the cultured cells when KIT receptors were blocked by the monoclonal anti-KIT antibody (ACK2). Apoptosis following treatment with ACK2 was detected by DNA fragmentation assay, in situ apoptosis detection, and electron microscopy. We noted a decrease in extracellular signal-related kinase (ERK) and ribosomal S6 kinase (RSK) protein expression following ACK2 incubation. Western blot analysis and real-time quantitative RT-PCR revealed an apparent time-dependent reduction in Bcl-2 protein levels with respect to ACK2 within the NCCmelb4 cells. In terms of Bax expression, a difference was not found. Fas and caspase8 proteins increased time-dependently in proportion to ACK2 incubation. We noted apoptotic cell death upon addition of ACK2, with evidence of possible involvement of Bcl-2 and Fas in the induction of apoptosis. In contrast, no significant correlation between Fas ligand (Fas-L) expression and ACK2 was found. Fas activation appears to occur independent of Fas-L during ACK2-induced cell death. Therefore, we propose that Fas-L expression in NCCmelb4 cells does not play a major role in facilitating apoptosis. Furthermore, we hypothesize that these molecules combined with SCF/KIT play an important role in regulating the induction of vertebrate NCC apoptosis during embryogenesis.

Melanin pigmentation in mammalian skin and its hormonal regulation

Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. Melanogenesis is under complex regulatory control by multiple agents interacting via pathways activated by receptor-dependent and -independent mechanisms, in hormonal, auto-, para-, or intracrine fashion. Because of the multidirectional nature and heterogeneous character of the melanogenesis modifying agents, its controlling factors are not organized into simple linear sequences, but they interphase instead in a multidimensional network, with extensive functional overlapping with connections arranged both in series and in parallel. The most important positive regulator of melanogenesis is the MC1 receptor with its ligands melanocortins and ACTH, whereas among the negative regulators agouti protein stands out, determining intensity of melanogenesis and also the type of melanin synthesized. Within the context of the skin as a stress organ, melanogenic activity serves as a unique molecular sensor and transducer of noxious signals and as regulator of local homeostasis. In keeping with these multiple roles, melanogenesis is controlled by a highly structured system, active since early embryogenesis and capable of superselective functional regulation that may reach down to the cellular level represented by single melanocytes. Indeed, the significance of melanogenesis extends beyond the mere assignment of a color trait.

Melanocyte Development: With a Message of Encouragement to Young Women Scientists

This is a semi-biographical review describing my research on melanocyte development and related personal experiences. Having been educated and trained as a dermatologist, I have been involved in many clinically-oriented studies, however, what has always interested me the most is pigment cell biology. Since I started working at St Marianna University in 1991, I have been undertaking research on melanocyte development and relevant growth factors using mice as models. My research in this field was inspired by my collaborations with various scientists, mostly from the field of biology. Many of these specialists I have met at meetings of the Societies of Pigment Cell Research (PCR). Stem cell factor (SCF, Kitl) and endothelin 3 (EDN3) have been identified as indispensable factors regulating the development of melanocytes. Mice mutant at loci encoding those factors (or their receptors) such as Sl/Sl (receptors W/W) and ls/ls (receptors s/s) have white coat colors and white patches, respectively. Our murine neural crest cell (NCC) primary cultures derived from Sl/Sl embryos showed that EDN3 cannot develop melanocyte precursors without SCF and that EDN3 can elicit proliferation and differentiation in the presence of SCF. These results suggest that without EDN3 and the endothelin type B receptor (EDNRB), melanocytes can not fully increase in number, which could well be the cause of the partial white coat color of ls/ls and s/s mice. Contamination with factors derived from the serum in medium or in feeder cells sometimes causes experimental errors, and therefore we established three immortal cell lines derived from NCC in different developmental stages and designated them as NCCmelb4, NCCmelb4M5 and NCCmelan5, all of which can survive without feeder cells. Using these cell lines and NCC primary cultures, we studied the effect of many factors related to melanocyte development. From the results, it has become evident that Vitamin D3 induces EDNRB expression by NCCmelb4 cells. In addition to the International Pigment Cell Conference (IPCC), I have also taken part in many annual meetings of the Japanese Society for Pigment Cell Research (JSPCR), Pan American Society for Pigment Cell Research (PASPCR) and European Society for Pigment Cell Research (ESPCR). Not only have I learned a great deal, I have enjoyed myself immensely at those meetings. Moreover, I have made many good friends there, some of whom I have collaborated with in my research. To conclude, I would like to give my message 'be ambitious' to young scientists, especially young women.

Expression and function of peroxisome proliferator-activated receptors in human melanocytes

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) belong to the superfamily of nuclear receptors that heterodimerize with the retinoic X receptor. Agonists of PPAR have been known to play an important role in cellular responses including proliferation and differentiation. The expression and function of PPARs have not been investigated in human melanocytes, although they have been widely demonstrated in keratinocytes of the skin.

OBJECTIVES

To investigate the expression of PPARs in human melanocytes and the effects of PPAR activators on melanocyte growth and melanogenesis.

METHODS

We used immunocytochemistry and Western blot analysis to determine whether PPARs are expressed in melanocytes. To investigate further expression of PPAR subtypes, reverse transcriptase-polymerase chain reaction analysis was performed using PPAR subtype-specific oligonucleotides. The cell proliferation was measured using the Coulter counter. The effects on pigmentation were investigated with measurement of melanin contents, tyrosinase activity and its expression.

RESULTS

The mRNA of all three PPAR subtypes, PPAR-alpha, PPAR-beta/delta and PPAR-gamma, were expressed in melanocytes. Activators for PPAR-alpha (WY-14643) and PPAR-gamma (ciglitazone) inhibited proliferation of melanocytes in a dose-dependent manner, whereas bezafibrate, a preferential activator for PPAR-beta/delta, had no effect. This growth inhibition was accompanied by the morphological change of the melanocytes to an activated form with an increased number of dendrites and enlarged cell area compared with the control. The WY-14643 and ciglitazone also appeared to stimulate the melanin synthesis of melanocytes. This increase in pigmentation was due to stimulation of the tyrosinase activity without an increase in the expression of tyrosinase.

CONCLUSIONS

PPARs are expressed in human melanocytes and PPAR-alpha and PPAR-gamma activators inhibit melanocyte growth and stimulate melanogenesis.

Dct::lacZ ES Cells: A Novel Cellular Model to Study Melanocyte Determination and Differentiation

Embryonic stem (ES) cells differentiate into various cell lineages in vitro. A procedure was previously designed to promote the differentiation of ES cells towards the melanocyte lineage and to obtain large and reproducible amounts of melanocytes. To elucidate the main events that lead to the development of melanocytes in vitro, we used transgenic Dct::lacZ mouse blastocysts to establish ES cell lines expressing the lacZ reporter gene under the control of the Dct promoter. Dct, a melanoblast marker, is expressed just after melanoblast determination in vivo. We evaluated the importance of recruitment, proliferation and differentiation during melanocyte ontogeny after the in vitro differentiation of Dct::lacZ ES cells into melanocytes. We showed that bFGF and cholera toxin induce precocious melanoblast determination, associated with early melanocyte differentiation. Edn3 induced melanoblast proliferation and long-term melanoblast recruitment, but not precocious determination. The lack of basic Fibroblast Growth Factor (bFGF) and cholera toxin can be partially compensated by Edn3. Thus, Dct::lacZ ES cells can be used as a model to study determination, proliferation and differentiation in the melanocyte lineage in vitro.