On the role of classical and novel forms of vitamin D in melanoma progression and management

ICAT mediates the inhibition of stemness and tumorigenesis in acute myeloid leukemia cells induced by 1,25-(OH)2D3

Background

The role of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) in cancer prevention and treatment is an emerging topic of interest. However, its effects on the stemness of acute myeloid leukemia (AML) cells are poorly understood.

Methods

The proliferation and differentiation of AML cells (HL60 and NB4) were investigated by the CCK-8 assay, immunocytochemical staining, and flow cytometry. The abilities of HL60 and NB4 cells to form spheres were examined by the cell sphere formation assay. In addition, the levels of stemness-associated markers (SOX2, Nanog, OCT4, and c-Myc) in HL60 and NB4 cells were measured by western blotting and quantitative real-time polymerase chain reaction. Moreover, we obtained β-catenin-interacting protein 1 (ICAT)-knockout and ICAT-overexpressing HL-60 cells using gene editing and lentiviral infection techniques and investigated the role of ICAT in modulating the stemness-inhibiting effects of 1,25-(OH)2D3 using the aforementioned experimental methods. Finally, we validated our findings in vivo using NOD/SCID mice.

Results

1,25-(OH)2D3 inhibited the proliferation and stemness of AML cells (HL60 and NB4) and induced their differentiation into monocytes. Additionally, the knockdown of ICAT in HL60 cells attenuated the inhibitory effects of 1,25-(OH)2D3 on proliferation and stemness and suppressed the expression of stemness markers. Conversely, overexpression of ICAT enhanced the aforementioned inhibitory effects of 1,25-(OH)2D3. Consistently, in NOD/SCID mice, 1,25-(OH)2D3 suppressed tumor formation by HL-60 cells, and the effects of ICAT knockdown or overexpression on 1,25-(OH)2D3 aligned with the in vitro findings.

Conclusion

1,25-(OH)2D3 inhibits AML cell stemness, possibly through modulation of the ICAT-mediated Wnt/β-catenin signaling pathway.

Anticancer Activity of Vitamin D, Lumisterol and Selected Derivatives against Human Malignant Melanoma Cell Lines

Despite the recent development of improved methods of treating melanoma such as targeted therapy, immunotherapy or combined treatment, the number of new cases worldwide is increasing. It is well known that active metabolites of vitamin D3 and lumisterol (L3) exert photoprotective and antiproliferative effects on the skin, while UV radiation is a major environmental risk factor for melanoma. Thus, many natural metabolites and synthetic analogs of steroidal and secosteroidal molecules have been tested on various cancer cells and in animal models. In this study, we tested the anti-melanoma properties of several natural derivatives of vitamin D3 and L3 in comparison to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). A significant decrease in melanoma cell proliferation and cell mobility was observed for selected derivatives, with (25R)-27-hydroxyL3 showing the highest potency (lowest IC50) in A375 cells but lower potency in SK-MEL-28 cells, whereas the parent L3 failed to inhibit proliferation. The efficacy (% inhibition) by 1,24,25(OH)3D3 and 1,25(OH)2D3 were similar in both cell types. 1,25(OH)2D3 showed higher potency than 1,24,25(OH)3D3 in SK-MEL-28 cells, but lower potency in A375 cells for the inhibition of proliferation. As for 1,25(OH)2D3, but not the other derivatives tested, treatment of melanoma cells with 1,24,25(OH)3D3 markedly increased the expression of CYP24A1, enhanced translocation of the vitamin D receptor (VDR) from the cytoplasm to the nucleus and also decreased the expression of the proliferation marker Ki67. The effects of the other compounds tested were weaker and occurred only under certain conditions. Our data indicate that 1,24,25(OH)3D3, which has undergone the first step in 1,25(OH)2D3 inactivation by being hydroxylated at C24, still shows anti-melanoma properties, displaying higher potency than 1,25(OH)2D3 in SK-MEL-28 cells. Furthermore, hydroxylation increases the potency of some of the lumisterol hydroxy-derivatives, as in contrast to L3, (25R)-27(OH)L3 effectively inhibits proliferation and migration of the human malignant melanoma cell line A375.

Biological Effects of CYP11A1-Derived Vitamin D and Lumisterol Metabolites in the Skin

Novel pathways of vitamin D3, lumisterol 3 (L3), and tachysterol 3 (T3) activation have been discovered, initiated by CYP11A1 and/or CYP27A1 in the case of L3 and T3. The resulting hydroxymetabolites enhance protection of skin against DNA damage and oxidative stress; stimulate keratinocyte differentiation; exert anti-inflammatory, antifibrogenic, and anticancer activities; and inhibit cell proliferation in a structure-dependent manner. They act on nuclear receptors, including vitamin D receptor, aryl hydrocarbon receptor, LXRα/β, RAR-related orphan receptor α/γ, and peroxisome proliferator-activated receptor-γ, with selectivity defined by their core structure and distribution of hydroxyl groups. They can activate NRF2 and p53 and inhibit NF-κB, IL-17, Shh, and Wnt/β-catenin signaling. Thus, they protect skin integrity and physiology.

Evolutionary formation of melatonin and vitamin D in early life forms: insects take centre stage

Melatonin, a product of tryptophan metabolism via serotonin, is a molecule with an indole backbone that is widely produced by bacteria, unicellular eukaryotic organisms, plants, fungi and all animal taxa. Aside from its role in the regulation of circadian rhythms, it has diverse biological actions including regulation of cytoprotective responses and other functions crucial for survival across different species. The latter properties are also shared by its metabolites including kynuric products generated by reactive oxygen species or phototransfomation induced by ultraviolet radiation. Vitamins D and related photoproducts originate from phototransformation of ∆5,7 sterols, of which 7-dehydrocholesterol and ergosterol are examples. Their ∆5,7 bonds in the B ring absorb solar ultraviolet radiation [290-315 nm, ultraviolet B (UVB) radiation] resulting in B ring opening to produce previtamin D, also referred to as a secosteroid. Once formed, previtamin D can either undergo thermal-induced isomerization to vitamin D or absorb UVB radiation to be transformed into photoproducts including lumisterol and tachysterol. Vitamin D, as well as the previtamin D photoproducts lumisterol and tachysterol, are hydroxylated by cyochrome P450 (CYP) enzymes to produce biologically active hydroxyderivatives. The best known of these is 1,25-dihydroxyvitamin D (1,25(OH)2D) for which the major function in vertebrates is regulation of calcium and phosphorus metabolism. Herein we review data on melatonin production and metabolism and discuss their functions in insects. We discuss production of previtamin D and vitamin D, and their photoproducts in fungi, plants and insects, as well as mechanisms for their enzymatic activation and suggest possible biological functions for them in these groups of organisms. For the detection of these secosteroids and their precursors and photoderivatives, as well as melatonin metabolites, we focus on honey produced by bees and on body extracts of Drosophila melanogaster. Common biological functions for melatonin derivatives and secosteroids such as cytoprotective and photoprotective actions in insects are discussed. We provide hypotheses for the photoproduction of other secosteroids and of kynuric metabolites of melatonin, based on the known photobiology of ∆5,7 sterols and of the indole ring, respectively. We also offer possible mechanisms of actions for these unique molecules and summarise differences and similarities of melatoninergic and secosteroidogenic pathways in diverse organisms including insects.

Antioxidant Functions of Vitamin D and CYP11A1-Derived Vitamin D, Tachysterol, and Lumisterol Metabolites: Mechanisms, Clinical Implications, and Future Directions

Evidence is increasing that vitamin D and CYP11A1-derived vitamin D, tachysterol, and lumisterol metabolites play a significant antioxidant role beyond its classical functions in bone health and calcium metabolism. Several recent studies have linked these elements to reduced oxidative stress as well as improved immune, cardiovascular, and neurological functions as a result of chronic kidney disease and cancer. Additionally, supplementation with this vitamin has been shown to be one of the most cost-effective micronutrient interventions worldwide, highlighting its potential as a therapeutic approach. The underlying mechanisms and implications of this antioxidant function of vitamin D or CYP11A1-derived vitamin D, tachysterol, and lumisterol metabolites are not well understood. This comprehensive and narrative review is aimed at summarizing the current evidence regarding the molecular mechanisms implicated in this antioxidant function of vitamin D, as well as to provide a general overview and to identify key research areas for the future, offering an extensive perspective that can guide both researchers and clinicians in the management of diseases associated with oxidative stress and/or insufficient vitamin D status.

Advances in biomedical applications of vitamin D for VDR targeted management of obesity and cancer

BACKGROUND

1,25(OH)2D3 is a fat-soluble vitamin, involved in regulating Ca2+ homeostasis in the body. Its storage in adipose tissue depends on the fat content of the body. Obesity is the result of abnormal lipid deposition due to the prolonged positive energy balance and increases the risk of several cancer types. Furthermore, it has been associated with vitamin D deficiency and defined as a low 25(OH)2D3 blood level. In addition, 1,25(OH)2D3 plays vital roles in Ca2+-Pi and glucose metabolism in the adipocytes of obese individuals and regulates the expressions of adipogenesis-associated genes in mature adipocytes.

SCOPE AND APPROACH

The present contribution focused on the VDR mediated mechanisms interconnecting the obese condition and cancer proliferation due to 1,25(OH)2D3-deficiency in humans. This contribution also summarizes the identification and development of molecular targets for VDR-targeted drug discovery.

KEY FINDINGS AND CONCLUSIONS

Several studies have revealed that cancer development in a background of 1,25(OH)2D3 deficient obesity involves the VDR gene. Moreover, 1,25(OH)2D3 is also known to influence several cellular processes, including differentiation, proliferation, and adhesion. The multifaceted physiology of obesity has improved our understanding of the cancer therapeutic targets. However, currently available anti-cancer drugs are notorious for their side effects, which have raised safety issues. Thus, there is interest in developing 1,25(OH)2D3-based therapies without any side effects.

Malignant Melanoma: An Overview, New Perspectives, and Vitamin D Signaling

Melanoma, originating through malignant transformation of melanin-producing melanocytes, is a formidable malignancy, characterized by local invasiveness, recurrence, early metastasis, resistance to therapy, and a high mortality rate. This review discusses etiologic and risk factors for melanoma, diagnostic and prognostic tools, including recent advances in molecular biology, omics, and bioinformatics, and provides an overview of its therapy. Since the incidence of melanoma is rising and mortality remains unacceptably high, we discuss its inherent properties, including melanogenesis, that make this disease resilient to treatment and propose to use AI to solve the above complex and multidimensional problems. We provide an overview on vitamin D and its anticancerogenic properties, and report recent advances in this field that can provide solutions for the prevention and/or therapy of melanoma. Experimental papers and clinicopathological studies on the role of vitamin D status and signaling pathways initiated by its active metabolites in melanoma prognosis and therapy are reviewed. We conclude that vitamin D signaling, defined by specific nuclear receptors and selective activation by specific vitamin D hydroxyderivatives, can provide a benefit for new or existing therapeutic approaches. We propose to target vitamin D signaling with the use of computational biology and AI tools to provide a solution to the melanoma problem.

Melatonin/Sericin Wound Healing Patches: Implications for Melanoma Therapy

Melatonin and sericin exhibit antioxidant properties and may be useful in topical wound healing patches by maintaining redox balance, cell integrity, and regulating the inflammatory response. In human skin, melatonin suppresses damage caused by ultraviolet radiation (UVR) which involves numerous mechanisms associated with reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and enhancing apoptosis. Sericin is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). It is of interest because of its biodegradability, anti-oxidative, and anti-bacterial properties. Sericin inhibits tyrosinase activity and promotes cell proliferation that can be supportive and useful in melanoma treatment. In recent years, wound healing patches containing sericin and melatonin individually have attracted significant attention by the scientific community. In this review, we summarize the state of innovation of such patches during 2021-2023. To date, melatonin/sericin-polymer patches for application in post-operational wound healing treatment has been only sparingly investigated and it is an imperative to consider these materials as a promising approach targeting for skin tissue engineering or regenerative dermatology.

Vitamin D in Melanoma: Potential Role of Cytochrome P450 Enzymes

Vitamin D is a promising anticancer agent for the prevention and treatment of several cancers, including melanoma. Low 25-hydroxyvitamin D levels, a routinely used marker for vitamin D, have been suggested as one of the factors in the development and progression of melanoma. The parent vitamin D needs activation by cytochrome P450 (CYP) enzymes to exert its actions via the vitamin D receptor (VDR). This review discusses the role of vitamin D in melanoma and how CYP-mediated metabolism can potentially affect the actions of vitamin D. Through interacting with the retinoid X receptor, VDR signaling leads to anti-inflammatory, antioxidative, and anticancer actions. Calcitriol, the dihydroxylated form of vitamin D3, is the most active and potent ligand of VDR. CYP27A1, CYP27B1, and CYP2R1 are involved in the activation of vitamin D, whereas CYP24A1 and CYP3A4 are responsible for the degradation of the active vitamin D. CYP24A1, the primary catabolic enzyme of calcitriol, is overexpressed in melanoma tissues and cells. Several drug classes and natural health products can modulate vitamin D-related CYP enzymes and eventually cause lower levels of vitamin D and its active metabolites in tissues. Although the role of vitamin D in the development of melanoma is yet to be fully elucidated, it has been proposed that melanoma prevention may be significantly aided by increased vitamin D signaling. Furthermore, selective targeting of the catabolic enzymes responsible for vitamin D degradation could be a plausible strategy in melanoma therapy. Vitamin D signaling can be improved by utilizing dietary supplements or by modulating CYP metabolism. A positive association exists between the intake of vitamin D supplements and improved prognosis for melanoma patients. Further investigation is required to determine the function of vitamin D supplementation and specific enzyme targeting in the prevention of melanoma.

Causal association between serum 25-Hydroxyvitamin D levels and cutaneous melanoma: a two-sample Mendelian randomization study

Background

Despite numerous observational studies on the association between serum 25-Hydroxyvitamin D levels and cutaneous melanoma, causal inferences remain ambiguous due to confounding and reverse causality. This study aimed to elucidate the causal relationship between serum 25-Hydroxyvitamin D levels and melanoma incidence using Mendelian randomization (MR).

Methods

A two-sample MR was conducted using genetic variants associated with serum 25-Hydroxyvitamin D levels as instrumental variables. Summary statistics for these variants were derived from genome-wide association studies, and those for melanoma risk were obtained from a comprehensive melanoma case-control study. Robustness of the results was assessed through sensitivity analyses, including the "leave-one-out" approach and tests for potential pleiotropy.

Results

The MR analysis provided substantial evidence of a positive causal relationship between serum 25-Hydroxyvitamin D levels and the incidence of cutaneous melanoma, suggesting that each unit increase in serum 25-Hydroxyvitamin D levels corresponds with an increased risk of melanoma. Tests for pleiotropy showed minimal effects, and the sensitivity analysis confirmed no disproportionate influence by any individual single nucleotide polymorphism (SNP).

Conclusion

The findings indicated a potentially causal positive association between serum 25-Hydroxyvitamin D levels and melanoma risk, challenging traditional beliefs about vitamin D's role in melanoma. This emphasizes the need for a balanced and personalized approach to vitamin D supplementation and sun exposure, particularly in high-risk populations. These results should be interpreted with caution due to potential unrecognized pleiotropy and confounding factors. Future research should focus on validating these findings in diverse populations and exploring underlying biological mechanisms.

Environmental Air Pollutants Affecting Skin Functions with Systemic Implications

The increase in air pollution worldwide represents an environmental risk factor that has global implications for the health of humans worldwide. The skin of billions of people is exposed to a mixture of harmful air pollutants, which can affect its physiology and are responsible for cutaneous damage. Some polycyclic aromatic hydrocarbons are photoreactive and could be activated by ultraviolet radiation (UVR). Therefore, such UVR exposure would enhance their deleterious effects on the skin. Air pollution also affects vitamin D synthesis by reducing UVB radiation, which is essential for the production of vitamin D3, tachysterol, and lumisterol derivatives. Ambient air pollutants, photopollution, blue-light pollution, and cigarette smoke compromise cutaneous structural integrity, can interact with human skin microbiota, and trigger or exacerbate a range of skin diseases through various mechanisms. Generally, air pollution elicits an oxidative stress response on the skin that can activate the inflammatory responses. The aryl hydrocarbon receptor (AhR) can act as a sensor for small molecules such as air pollutants and plays a crucial role in responses to (photo)pollution. On the other hand, targeting AhR/Nrf2 is emerging as a novel treatment option for air pollutants that induce or exacerbate inflammatory skin diseases. Therefore, AhR with downstream regulatory pathways would represent a crucial signaling system regulating the skin phenotype in a Yin and Yang fashion defined by the chemical nature of the activating factor and the cellular and tissue context.

Vitamin D Modulates the Response of Patient-Derived Metastatic Melanoma Cells to Anticancer Drugs

Melanoma is considered a lethal and treatment-resistant skin cancer with a high risk of recurrence, making it a major clinical challenge. Our earlier studies documented that 1,25(OH)₂D₃ and its low-calcaemic analogues potentiate the effectiveness of dacarbazine and cediranib, a pan-VEGFR inhibitor. In the current study, a set of patient-derived melanoma cultures was established and characterised as a preclinical model of human melanoma. Thus, patient-derived cells were preconditioned with 1,25(OH)₂D₃ and treated with cediranib or vemurafenib, a BRAF inhibitor, depending on the BRAF mutation status of the patients enrolled in the study. 1,25(OH)₂D₃ preconditioning exacerbated the inhibition of patient-derived melanoma cell growth and motility in comparison to monotherapy with cediranib. A significant decrease in mitochondrial respiration parameters, such as non-mitochondrial oxygen consumption, basal respiration and ATP-linked respiration, was observed. It seems that 1,25(OH)₂D₃ preconditioning enhanced cediranib efficacy via the modulation of mitochondrial bioenergetics. Additionally, 1,25(OH)₂D₃ also decreased the viability and mobility of the BRAF+ patient-derived cells treated with vemurafenib. Interestingly, regardless of the strict selection, cancer-derived fibroblasts (CAFs) became the major fraction of cultured cells over time, suggesting that melanoma growth is dependent on CAFs. In conclusion, the results of our study strongly emphasise that the active form of vitamin D, 1,25(OH)₂D₃, might be considered as an adjuvant agent in the treatment of malignant melanoma.

Nongenomic Activities of Vitamin D

Vitamin D shows a variety of pleiotropic activities which cannot be fully explained by the stimulation of classic pathway- and vitamin D receptor (VDR)-dependent transcriptional modulation. Thus, existence of rapid and nongenomic responses to vitamin D was suggested. An active form of vitamin D (calcitriol, 1,25(OH)₂D₃) is an essential regulator of calcium-phosphate homeostasis, and this process is tightly regulated by VDR genomic activity. However, it seems that early in evolution, the production of secosteroids (vitamin-D-like steroids) and their subsequent photodegradation served as a protective mechanism against ultraviolet radiation and oxidative stress. Consequently, direct cell-protective activities of vitamin D were proven. Furthermore, calcitriol triggers rapid calcium influx through epithelia and its uptake by a variety of cells. Subsequently, protein disulfide-isomerase A3 (PDIA3) was described as a membrane vitamin D receptor responsible for rapid nongenomic responses. Vitamin D was also found to stimulate a release of secondary massagers and modulate several intracellular processes-including cell cycle, proliferation, or immune responses-through wingless (WNT), sonic hedgehog (SSH), STAT1-3, or NF-kappaB pathways. Megalin and its coreceptor, cubilin, facilitate the import of vitamin D complex with vitamin-D-binding protein (DBP), and its involvement in rapid membrane responses was suggested. Vitamin D also directly and indirectly influences mitochondrial function, including fusion-fission, energy production, mitochondrial membrane potential, activity of ion channels, and apoptosis. Although mechanisms of the nongenomic responses to vitamin D are still not fully understood, in this review, their impact on physiology, pathology, and potential clinical applications will be discussed.

Circadian clock-mediated nuclear receptors in cancer

Circadian system coordinates the daily periodicity of physiological and biochemical functions to adapt to environmental changes. Circadian disruption has been identified to increase the risk of cancer and promote cancer progression, but the underlying mechanism remains unclear. And further mechanistic understanding of the crosstalk between clock components and cancer is urgent to achieve clinical anticancer benefits from chronochemotherapy. Recent studies discover that several nuclear receptors regulating circadian clock, also play crucial roles in mediating multiple cancer processes. In this review, we aim to summarize the latest developments of clock-related nuclear receptors in cancer biology and dissect mechanistic insights into how nuclear receptors coordinate with circadian clock to regulate tumorigenesis and cancer treatment. A better understanding of circadian clock-related nuclear receptors in cancer could help prevent tumorigenesis and improve anticancer efficacy.

Vitamin D Signaling in Psoriasis: Pathogenesis and Therapy

Psoriasis is a systemic, chronic, immune-mediated disease that affects approximately 2-3% of the world's population. The etiology and pathophysiology of psoriasis are still unknown, but the activation of the adaptive immune system with the main role of T-cells is key in psoriasis pathogenesis. The modulation of the local neuroendocrine system with the downregulation of pro-inflammatory and the upregulation of anti-inflammatory messengers represent a promising adjuvant treatment in psoriasis therapies. Vitamin D receptors and vitamin D-mediated signaling pathways function in the skin and are essential in maintaining the skin homeostasis. The active forms of vitamin D act as powerful immunomodulators of clinical response in psoriatic patients and represent the effective and safe adjuvant treatments for psoriasis, even when high doses of vitamin D are administered. The phototherapy of psoriasis, especially UVB-based, changes the serum level of 25(OH)D, but the correlation of 25(OH)D changes and psoriasis improvement need more clinical trials, since contradictory data have been published. Vitamin D derivatives can improve the efficacy of psoriasis phototherapy without inducing adverse side effects. The anti-psoriatic treatment could include non-calcemic CYP11A1-derived vitamin D hydroxyderivatives that would act on the VDR or as inverse agonists on RORs or activate alternative nuclear receptors including AhR and LXRs. In conclusion, vitamin D signaling can play an important role in the natural history of psoriasis. Selective targeting of proper nuclear receptors could represent potential treatment options in psoriasis.

CYP11A1‑derived vitamin D hydroxyderivatives as candidates for therapy of basal and squamous cell carcinomas

Hydroxyderivatives of vitamin D3, including classical 1,25(OH)2D3 and novel CYP11A1‑derived hydroxyderivatives, exert their biological activity by acting as agonists on the vitamin D receptor (VDR) and inverse agonists on retinoid‑related orphan receptors (ROR)α and γ. The anticancer activities of CYP11A1‑derived hydroxyderivatives were tested using cell biology, tumor biology and molecular biology methods in human A431 and SCC13 squamous (SCC)‑ and murine ASZ001 basal (BCC)‑cell carcinomas, in comparison with classical 1,25(OH)2D3. Vitamin D3‑hydroxyderivatives with or without a C1α(OH) inhibited cell proliferation in a dose‑dependent manner. While all the compounds tested had similar effects on spheroid formation by A431 and SCC13 cells, those with a C1α(OH) group were more potent in inhibiting colony and spheroid formation in the BCC line. Potent anti‑tumorigenic activity against the BCC line was exerted by 1,25(OH)2D3, 1,20(OH)2D3, 1,20,23(OH)3D3, 1,20,24(OH)3D3, 1,20,25(OH)3D3 and 1,20,26(OH)3D3, with smaller effects seen for 25(OH)D3, 20(OH)D3 and 20,23(OH)2D3. 1,25(OH)2D3, 1,20(OH)2D3 and 20(OH)D3 inhibited the expression of GLI1 and β‑catenin in ASZ001 cells. In A431 cells, these compounds also decreased the expression of GLI1 and stimulated involucrin expression. VDR, RORγ, RORα and CYP27B1 were detected in A431, SCC13 and ASZ001 lines, however, with different expression patterns. Immunohistochemistry performed on human skin with SCC and BCC showed nuclear expression of all three of these receptors, as well as megalin (transmembrane receptor for vitamin D‑binding protein), the level of which was dependent on the type of cancer and antigen tested in comparison with normal epidermis. Classical and CYP11A1‑derived vitamin D3‑derivatives exhibited anticancer‑activities on skin cancer cell lines and inhibited GLI1 and β‑catenin signaling in a manner that was dependent on the position of hydroxyl groups. The observed expression of VDR, RORγ, RORα and megalin in human SCC and BCC suggested that they might provide targets for endogenously produced or exogenously applied vitamin D hydroxyderivatives and provide excellent candidates for anti‑cancer therapy.

Metabolic activation of tachysterol3 to biologically active hydroxyderivatives that act on VDR, AhR, LXRs, and PPARγ receptors

CYP11A1 and CYP27A1 hydroxylate tachysterol3 , a photoproduct of previtamin D3 , producing 20S-hydroxytachysterol3 [20S(OH)T3 ] and 25(OH)T3 , respectively. Both metabolites were detected in the human epidermis and serum. Tachysterol3 was also detected in human serum at a concentration of 7.3 ± 2.5 ng/ml. 20S(OH)T3 and 25(OH)T3 inhibited the proliferation of epidermal keratinocytes and dermal fibroblasts and stimulated the expression of differentiation and anti-oxidative genes in keratinocytes in a similar manner to 1,25-dihydroxyvitamin D3 [1,25(OH)2 D3 ]. They acted on the vitamin D receptor (VDR) as demonstrated by image flow cytometry and the translocation of VDR coupled GFP from the cytoplasm to the nucleus of melanoma cells, as well as by the stimulation of CYP24A1 expression. Functional studies using a human aryl hydrocarbon receptor (AhR) reporter assay system revealed marked activation of AhR by 20S(OH)T3 , a smaller effect by 25(OH)T3 , and a minimal effect for their precursor, tachysterol3 . Tachysterol3 hydroxyderivatives showed high-affinity binding to the ligan-binding domain (LBD) of the liver X receptor (LXR) α and β, and the peroxisome proliferator-activated receptor γ (PPARγ) in LanthaScreen TR-FRET coactivator assays. Molecular docking using crystal structures of the LBDs of VDR, AhR, LXRs, and PPARγ revealed high docking scores for 20S(OH)T3 and 25(OH)T3 , comparable to their natural ligands. The scores for the non-genomic-binding site of the VDR were very low indicating a lack of interaction with tachysterol3 ligands. Our identification of endogenous production of 20S(OH)T3 and 25(OH)T3 that are biologically active and interact with VDR, AhR, LXRs, and PPARγ, provides a new understanding of the biological function of tachysterol3 .

Consideration of possible effects of vitamin D on established cancer, with reference to malignant melanoma

Epidemiological studies indicate that Vitamin D has a beneficial, inhibitory effect on cancer development and subsequent progression, including melanoma (MM), and favourable MM outcome has been reported as directly related to vitamin D3 status, assessed by serum 25-hydroxyvitamin D3 (25[OH]D3 ) levels taken at diagnosis. It has been recommended that MM patients with deficient levels of 25(OH)D3 be given vitamin D3 . We examine possible beneficial or detrimental effects of treating established cancer with vitamin D3 . We consider the likely biological determinants of cancer outcome, the reported effects of vitamin D3 on these in both cancerous and non-cancerous settings, and how the effect of vitamin D3 might change depending on the integrity of tumour vitamin D receptor (VDR) signalling. We would argue that the effect of defective tumour VDR signalling could result in loss of suppression of growth, reduction of anti-tumour immunity, with potential antagonism of the elimination phase and enhancement of the escape phase of tumour immunoediting, possibly increased angiogenesis but continued suppression of inflammation. In animal models, having defective VDR signalling, vitamin D3 administration decreased survival and increased metastases. Comparable studies in man are lacking but in advanced disease, a likely marker of defective VDR signalling, studies have shown modest or no improvement in outcome with some evidence of worsening. Work is needed in assessing the integrity of tumour VDR signalling and the safety of vitamin D3 supplementation when defective.

Vitamin D: A Potential Star for Treating Chronic Pancreatitis

Chronic pancreatitis (CP) is a chronic inflammatory and fibrotic disease of the pancreas. The incidence of CP is increasing worldwide but the effective therapies are lacking. Hence, it is necessary to identify economical and effective agents for the treatment of CP patients. Vitamin D (VD) and its analogues have been confirmed as pleiotropic regulators of cell proliferation, apoptosis, differentiation and autophagy. Clinical studies show that VD deficiency is prevalent in CP patients. However, the correlation between VD level and the risk of CP remains controversial. VD and its analogues have been demonstrated to inhibit pancreatic fibrosis by suppressing the activation of pancreatic stellate cells and the production of extracellular matrix. Limited clinical trials have shown that the supplement of VD can improve VD deficiency in patients with CP, suggesting a potential therapeutic value of VD in CP. However, the mechanisms by which VD and its analogues inhibit pancreatic fibrosis have not been fully elucidated. We are reviewing the current literature concerning the risk factors for developing CP, prevalence of VD deficiency in CP, mechanisms of VD action in PSC-mediated fibrogenesis during the development of CP and potential therapeutic applications of VD and its analogues in the treatment of CP.

Molecular and structural basis of interactions of vitamin D3 hydroxyderivatives with aryl hydrocarbon receptor (AhR): An integrated experimental and computational study

To better understand the molecular and structural basis underlying the interaction of vitamin D3 hydroxyderivatives with AhR, molecular simulation was used to probe the binding of 1,20(OH)₂D3, 1,25(OH)₂D3, 20,23(OH)₂D3 and 20(OH)D3 to AhR. qPCR showed that vitamin D3 derivatives stimulate expression of cyp1A1 and cyp1B1 genes that are downstream targets of AhR signaling. These secosteroids stimulated the translocation of the AhR to the nucleus, as measured by flow cytometry and western blotting. Molecular dynamics simulations were used to model the binding of vitamin D3 derivatives to AhR to examine their influence on the structure, conformation and dynamics of the AhR ligand binding domain (LBD). Binding thermodynamics, conformation, secondary structure, dynamical motion and electrostatic potential of AhR were analyzed. The molecular docking scores and binding free energy were all favorable for the binding of D3 derivatives to the AhR. These established ligands and the D3 derivatives are predicted to have different patterns of hydrogen bond formation with the AhR, and varied residue conformational fluctuations and dynamical motion for the LBD. These changes could alter the shape, size and electrostatic potential distribution of the ligand binding pocket, contributing to the different binding affinities of AhR for the natural ligands and D3 derivatives.

Low Vitamin D Status Predicts Poor Clinical Outcome in Advanced Melanoma Treated With Immune Checkpoint or BRAF/MEK Inhibitors: A Prospective Non-Interventional Side-by-Side Analysis

In melanoma and other malignancies, low vitamin D status is associated with increased risk and poor prognosis. However, there are limited data of the impact of 25(OH)D serum concentration (s.c.) on clinical outcome in advanced melanoma. We tested the hypothesis that vitamin D status is predictive of efficacy and safety in patients treated for metastasized melanoma with B-rapidly accelerated fibrosarcoma (BRAF), mitogen-activated protein kinase kinase (MEK), cytotoxic T lymphocyte-associated protein-4 (CTLA-4), and/or programmed cell death protein-1 (PD-1) inhibitors. Severe vitamin D deficiency [defined as 25(OH)D s.c. <10 ng/ml] was associated with markedly reduced overall (OS) and progress-free (PFS) survival, with increased tumor load [TL; measured as s.c. of S100 protein or lactate dehydrogenase (LDH)], and with a trend for higher frequency of adverse events (AEs). An increase in average 25(OH)D s.c. of 1 ng/ml was associated with a 3.9% reduced risk for progressive disease [hazard ratio (HR) = 0.961, p = 0.044], with a reduction of LDH s.c. of 3.86 U/l (p = 0.034, indicating a reduction of TL), and with a trend for reduced frequency of AEs (AE ratio -0.005; p = 0.295). Patients with average 25(OH)D s.c. ≥10 ng/ml and BRAF-mutant melanoma showed a trend for a higher frequency of AEs as compared to individuals with BRAF wild-type melanomas. Our data indicate that vitamin D deficiency is associated with poor clinical outcome in patients treated for metastasized melanoma with BRAF/MEK inhibitors or immunotherapy. Although it needs to be proven in future interventional trials whether optimizing serum 25(OH)D improves clinical outcome in these patients, we recommend that 25(OH)D s.c. should be analyzed and vitamin D deficiency treated in all patients with advanced melanoma.

Determinants of 25-hydroxyvitamin D Status in a Cutaneous Melanoma Population

Vitamin D status is influenced by well-known determinants, but factors associated with low 25-hydroxyvitamin D levels in the cutaneous melanoma population are not well defined. The aim of this study was to confirm the well-known determinants and to assess new determinants for 25-hydroxyvitamin D levels in a cutaneous melanoma population. In a prospectively included cohort of 387 patients with cutaneous melanoma the association of 25-hydroxyvitamin D levels with sex, age, body mass index, time of blood withdrawal, Fitzpatrick phototype, vitamin D supplementation, score for intensity of lifetime sun exposure, smoking, education level, hair and skin colour, eye colour, total number of benign naevi, freckles and parameters of chronic sun damage was investigated. In addition, 25-hydroxyvitamin D levels were correlated with pathological parameters of the primary tumour and melanoma stage (8th edition of the American Joint Committee on Cancer (AJCC). Univariate and multivariate logistic regressions were performed using R software. The following factors had a significant effect on vitamin D status: body mass index, seasonal time of blood sampling, vitamin D supplementation, and a subtype of skin, and hair colour.

Chemical synthesis, biological activities and action on nuclear receptors of 20S(OH)D3, 20S,25(OH)2D3, 20S,23S(OH)2D3 and 20S,23R(OH)2D3

New and more efficient routes of chemical synthesis of vitamin D₃ (D₃) hydroxy (OH) metabolites, including 20S(OH)D₃, 20S,23S(OH)₂D₃ and 20S,25(OH)₂D₃, that are endogenously produced in the human body by CYP11A1, and of 20S,23R(OH)₂D₃ were established. The biological evaluation showed that these compounds exhibited similar properties to each other regarding inhibition of cell proliferation and induction of cell differentiation but with subtle and quantitative differences. They showed both overlapping and differential effects on T-cell immune activity. They also showed similar interactions with nuclear receptors with all secosteroids activating vitamin D, liver X, retinoic acid orphan and aryl hydrocarbon receptors in functional assays and also as indicated by molecular modeling. They functioned as substrates for CYP27B1 with enzymatic activity being the highest towards 20S,25(OH)₂D₃ and the lowest towards 20S(OH)D₃. In conclusion, defining new routes for large scale synthesis of endogenously produced D₃-hydroxy derivatives by pathways initiated by CYP11A1 opens an exciting era to analyze their common and differential activities in vivo, particularly on the immune system and inflammatory diseases.

PTEN: A novel target for vitamin D in melanoma

Melanoma is the most dangerous form of skin cancer, with poor prognosis in advanced stages. Vitamin D, also produced by ultraviolet radiation, is known for its anti-proliferative properties in some cancers including melanoma. While vitamin D deficiency has been associated with advanced melanoma stage and higher levels of vitamin D have been associated with better outcomes, the role for vitamin D in melanoma remains unclear. Vitamin D synthesis is initiated upon UVB exposure of skin cells and results in formation of the active metabolite 1,25-dihydroxyvitamin D3 (1,25D). We have previously demonstrated that 1,25D plays a role in protection against ultraviolet radiation-induced DNA damage, immune suppression, and skin carcinogenesis. In this study 1,25D significantly reduced cell viability and increased caspase levels in human melanoma cell lines. This effect was not present in cells that lacked both phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a well-known tumour suppressor, and the vitamin D receptor (VDR). PTEN is frequently lost or mutated in melanoma. Incubation of selected melanoma cell lines with 1,25D resulted in significant increases in PTEN levels and downregulation of the AKT pathway and its downstream effectors. This suggests that 1,25D may act to reduce melanoma cell viability by targeting PTEN.

Vitamin D and Hypoxia: Points of Interplay in Cancer

Vitamin D is a hormone that, through its action, elicits a broad spectrum of physiological responses ranging from classic to nonclassical actions such as bone morphogenesis and immune function. In parallel, many studies describe the antiproliferative, proapoptotic, antiangiogenic effects of calcitriol (the active hormonal form) that contribute to its anticancer activity. Additionally, epidemiological data signify the inverse correlation between vitamin D levels and cancer risk. On the contrary, tumors possess several adaptive mechanisms that enable them to evade the anticancer effects of calcitriol. Such maladaptive processes are often a characteristic of the cancer microenvironment, which in solid tumors is frequently hypoxic and elicits the overexpression of Hypoxia-Inducible Factors (HIFs). HIF-mediated signaling not only contributes to cancer cell survival and proliferation but also confers resistance to anticancer agents. Taking into consideration that calcitriol intertwines with signaling events elicited by the hypoxic status cells, this review examines their interplay in cellular signaling to give the opportunity to better understand their relationship in cancer development and their prospect for the treatment of cancer.

The Challenge of Melanoma Chemoprevention

Melanoma is a treatment-resistant cancer of melanocytes. There is a serious unmet need for chemopreventive agents that can inhibit their evolution from preexisting dysplastic nevi. Low-dose aspirin and NSAIDs are potential chemopreventive candidates because they inhibit the enzyme COX-2 which has a number of procarcinogenic effects. Unfortunately, the clinical trial reported by Okwundu and colleagues in this issue of Cancer Prevention Research did not show an effect of aspirin on biomarkers associated with progression of premalignant dysplastic nevi to melanomas. Further clinical trials with other aspirin or NSAID biomarkers or clinical trials with other potential chemopreventive agents offer hope to those who are at increased risk for melanomas.See related article, p. 129.

Vitamin D Enhances Anticancer Properties of Cediranib, a VEGFR Inhibitor, by Modulation of VEGFR2 Expression in Melanoma Cells

Regardless of the recent groundbreaking introduction of personalized therapy, melanoma continues to be one of the most lethal skin malignancies. Still, a substantial proportion of patients either fail to respond to the therapy or will relapse over time, representing a challenging clinical problem. Recently, we have shown that vitamin D enhances the effectiveness of classical chemotherapeutics in the human malignant melanoma A375 cell line. In search for new combination strategies and adjuvant settings to improve melanoma patient outcomes in the current study, the effects of cediranib (AZD2171), an oral tyrosine kinase inhibitor of VEGFR1-3, PDGFR, and c-KIT, used in combination either with 1,25(OH)₂D₃ or with low-calcemic analog calcipotriol were tested on four human malignant melanoma cell lines (A375, MNT-1, RPMI-7951, and SK-MEL-28). Melanoma cells were pretreated with vitamin D and subsequently exposed to cediranib. We observed a marked decrease in melanoma cell proliferation (A375 and SK-MEL-28), G2/M cell cycle arrest, and a significant decrease in melanoma cell mobility in experimental conditions used (A375). Surprisingly, concurrently with a very desirable decrease in melanoma cell proliferation and mobility, we noticed the upregulation of VEGFR2 at both protein and mRNA levels. No effect of vitamin D was observed in MNT-1 and RPMI-7951 melanoma cells. It seems that vitamin D derivatives enhance cediranib efficacy by modulation of VEGFR2 expression in melanoma cells expressing VEGFR2. In conclusion, our experiments demonstrated that vitamin D derivatives hold promise as novel adjuvant candidates to conquer melanoma, especially in patients suffering from vitamin D deficiency. However, further extensive research is indispensable to reliably assess their potential benefits for melanoma patients.

Nutrition and melanoma prevention

There has been considerable research in recent years on dietary factors and/or nutritional elements that might impact melanoma risk. A wide variety of dietary compounds have been studied, but only a selected group will be discussed in this review. Many have promising in vitro evidence supporting their potential, and some have been associated with decreased melanoma risk in epidemiologic studies; however, data from randomized controlled trials in humans are lacking. Future studies may be able to clarify the potential role of dietary components in melanoma risk reduction.

The Role of the Vitamin D Receptor in the Pathogenesis, Prognosis, and Treatment of Cutaneous Melanoma

Melanoma is the malignant transformation of melanocytes and represents the most lethal form of skin cancer. While early-stage melanoma localized to the skin can be cured with surgical excision, metastatic melanoma often requires a multi-pronged approach and even then can exhibit treatment resistance. Understanding the molecular mechanisms involved in the pathogenesis of melanoma could lead to novel diagnostic, prognostic, and therapeutic strategies to ultimately decrease morbidity and mortality. One emerging candidate that may have value as both a prognostic marker and in a therapeutic context is the vitamin D receptor (VDR). VDR is a nuclear steroid hormone receptor activated by 1,25 dihydroxy-vitamin D3 [calcitriol, 1,25(OH)2D3]. While 1,25 dihydroxy-vitamin D3 is typically thought of in relation to calcium metabolism, it also plays an important role in cell proliferation, differentiation, programmed-cell death as well as photoprotection. This review discusses the role of VDR in the crosstalk between keratinocytes and melanocytes during melanomagenesis and summarizes the clinical data regarding VDR polymorphisms, VDR as a prognostic marker, and potential uses of vitamin D and its analogs as an adjuvant treatment for melanoma.

Unraveling the physiological roles of retinoic acid receptor-related orphan receptor α

Retinoic acid receptor-related orphan receptor-α (RORα) is a member of the orphan nuclear receptor family and functions as a transcriptional activator in response to circadian changes. Circadian rhythms are complex cellular mechanisms regulating diverse metabolic, inflammatory, and tumorigenic gene expression pathways that govern cyclic cellular physiology. Disruption of circadian regulators, including RORα, plays a critical role in tumorigenesis and facilitates the development of inflammatory hallmarks. Although RORα contributes to overall fitness among anticancer, anti-inflammatory, lipid homeostasis, and circadian clock mechanisms, the molecular mechanisms underlying the mode of transcriptional regulation by RORα remain unclear. Nonetheless, RORα has important implications for pharmacological prevention of cancer, inflammation, and metabolic diseases, and understanding context-dependent RORα regulation will provide an innovative approach for unraveling the functional link between cancer metabolism and rhythm changes.

The Impact of Vitamin D on Skin Aging

The active metabolites of vitamin D₃ (D₃) and lumisterol (L₃) exert a variety of antiaging and photoprotective effects on the skin. These are achieved through immunomodulation and include anti-inflammatory actions, regulation of keratinocytes proliferation, and differentiation programs to build the epidermal barrier necessary for maintaining skin homeostasis. In addition, they induce antioxidative responses, inhibit DNA damage and induce DNA repair mechanisms to attenuate premature skin aging and cancerogenesis. The mechanism of action would involve interaction with multiple nuclear receptors including VDR, AhR, LXR, reverse agonism on RORα and -γ, and nongenomic actions through 1,25D₃-MARRS receptor and interaction with the nongenomic binding site of the VDR. Therefore, active forms of vitamin D₃ including its canonical (1,25(OH)₂D₃) and noncanonical (CYP11A1-intitated) D₃ derivatives as well as L₃ derivatives are promising agents for the prevention, attenuation, or treatment of premature skin aging. They could be administrated orally and/or topically. Other forms of parenteral application of vitamin D₃ precursor should be considered to avoid its predominant metabolism to 25(OH)D₃ that is not recognized by CYP11A1 enzyme. The efficacy of topically applied vitamin D₃ and L₃ derivatives needs further clinical evaluation in future trials.

Knocking out the Vitamin D Receptor Enhances Malignancy and Decreases Responsiveness to Vitamin D3 Hydroxyderivatives in Human Melanoma Cells

Simple Summary

Active forms of vitamin D3, including 1,25(OH)₂D3, 20(OH)D3 and 1,20(OH)₂D3, inhibited cell proliferation, migration rate and the ability to form colonies and spheroids in the wild-type melanoma cell line, while cells with the vitamin D receptor (VDR) silenced showed an increased but not complete resistance to their action. Furthermore, silencing of the VDR in melanoma cells enhanced their proliferation as well as spheroid and colony formation and increased their migration rate. Previous clinicopathological studies have shown an inverse correlation between VDR expression, melanoma progression and poor outcome of the disease. Thus, the expression of VDR is not only necessary for the inhibition of melanoma growth by active forms of vitamin D, but the VDR can also function as a melanoma tumor suppressor gene.

Abstract

Vitamin D3 is not only involved in calcium and phosphate metabolism in humans, but it can also affect proliferation and differentiation of normal and cancer cells, including melanoma. The mechanism of the anti-cancer action of vitamin D3 is not fully understood. The nuclear vitamin D receptor (VDR) is crucial for the phenotypic effects of vitamin D hydroxyderivatives. VDR expression shows an inverse correlation with melanoma progression and poor outcome of the disease. In this study we knocked out the VDR in a human melanoma cell line using CRISPR methodology. This enhanced the proliferation of melanoma cells grown in monolayer culture, spheroids or colonies and their migration. Activated forms of vitamin D, including classical 1,25(OH)₂D3, 20(OH)D3 and 1,20(OH)₂D3, inhibited cell proliferation, migration rate and the ability to form colonies and spheroids in the wild-type melanoma cell line, while VDR KO cells showed a degree of resistance to their action. These results indicate that expression of VDR is important for the inhibition of melanoma growth induced by activated forms of vitamin D. In conclusion, based on our previous clinicopathological analyses and the current study, we suggest that the VDR can function as a melanoma tumor suppressor gene.

The significance of CYP11A1 expression in skin physiology and pathology

CYP11A1, a member of the cytochrome P450 family, plays several key roles in the human body. It catalyzes the first and rate-limiting step in steroidogenesis, converting cholesterol to pregnenolone. Aside from the classical steroidogenic tissues such as the adrenals, gonads and placenta, CYP11A1 has also been found in the brain, gastrointestinal tract, immune systems, and finally the skin. CYP11A1 activity in the skin is regulated predominately by StAR protein and hence cholesterol levels in the mitochondria. However, UVB, UVC, CRH, ACTH, cAMP, and cytokines IL-1, IL-6 and TNFα can also regulate its expression and activity. Indeed, CYP11A1 plays several critical roles in the skin through its initiation of local steroidogenesis and specific metabolism of vitamin D, lumisterol, and 7-dehydrocholesterol. Products of these pathways regulate the protective barrier and skin immune functions in a context-dependent fashion through interactions with a number of receptors. Disturbances in CYP11A1 activity can lead to skin pathology.

Vitamin D and lumisterol derivatives can act on liver X receptors (LXRs)

The interactions of derivatives of lumisterol (L3) and vitamin D3 (D3) with liver X receptors (LXRs) were investigated. Molecular docking using crystal structures of the ligand binding domains (LBDs) of LXRα and β revealed high docking scores for L3 and D3 hydroxymetabolites, similar to those of the natural ligands, predicting good binding to the receptor. RNA sequencing of murine dermal fibroblasts stimulated with D3-hydroxyderivatives revealed LXR as the second nuclear receptor pathway for several D3-hydroxyderivatives, including 1,25(OH)2D3. This was validated by their induction of genes downstream of LXR. L3 and D3-derivatives activated an LXR-response element (LXRE)-driven reporter in CHO cells and human keratinocytes, and by enhanced expression of LXR target genes. L3 and D3 derivatives showed high affinity binding to the LBD of the LXRα and β in LanthaScreen TR-FRET LXRα and β coactivator assays. The majority of metabolites functioned as LXRα/β agonists; however, 1,20,25(OH)3D3, 1,25(OH)2D3, 1,20(OH)2D3 and 25(OH)D3 acted as inverse agonists of LXRα, but as agonists of LXRβ. Molecular dynamics simulations for the selected compounds, including 1,25(OH)2D3, 1,20(OH)2D3, 25(OH)D3, 20(OH)D3, 20(OH)L3 and 20,22(OH)2L3, showed different but overlapping interactions with LXRs. Identification of D3 and L3 derivatives as ligands for LXRs suggests a new mechanism of action for these compounds.

Loss of retinoic acid receptor-related receptor alpha (Rorα) promotes the progression of UV-induced cSCC

Cutaneous squamous cell carcinoma (cSCC) is prevalent in the world, accounting for a huge part of non-melanoma skin cancer. Most cSCCs are associated with a distinct pre-cancerous lesion, the actinic keratosis (AK). However, the progression trajectory from normal skin to AK and cSCC has not been fully demonstrated yet. To identify genes involved in this progression trajectory and possible therapeutic targets for cSCC, here we constructed a UV-induced cSCC mouse model covering the progression from normal skin to AK to cSCC, which mimicked the solar UV radiation perfectly using the solar-like ratio of UVA and UVB, firstly. Then, transcriptome analysis and a series of bioinformatics analyses and cell experiments proved that Rorα is a key transcript factor during cSCC progression. Rorα could downregulate the expressions of S100a9 and Sprr2f in cSCC cells, which can inhibit the proliferation and migration in cSCC cells, but not the normal keratinocyte. Finally, further animal experiments confirmed the inhibitory effect of cSCC growth by Rorα in vivo. Our findings showed that Rorα would serve as a potential novel target for cSCC, which will facilitate the treatment of cSCC in the future.

Vitamin D regulation of energy metabolism in cancer

Vitamin D exerts anti-cancer effects in recent clinical trials and preclinical models. The actions of vitamin D are primarily mediated through its hormonal form, 1,25-dihydroxyvitamin D (1,25(OH)₂ D). Previous literature describing in vitro studies has predominantly focused on the anti-tumourigenic effects of the hormone, such as proliferation and apoptosis. However, recent evidence has identified 1,25(OH)₂ D as a regulator of energy metabolism in cancer cells, where requirements for specific energy sources at different stages of progression are dramatically altered. The literature suggests that 1,25(OH)₂ D regulates energy metabolism, including glucose, glutamine and lipid metabolism during cancer progression, as well as oxidative stress protection, as it is closely associated with energy metabolism. Mechanisms involved in energy metabolism regulation are an emerging area in which vitamin D may inhibit multiple stages of cancer progression.

Association among Vitamin D, Retinoic Acid-Related Orphan Receptors, and Vitamin D Hydroxyderivatives in Ovarian Cancer

Vitamin D and its derivatives, acting via the vitamin D receptor (VDR) and retinoic acid-related orphan receptors γ and α (RORγ and RORα), show anticancer properties. Since pathological conditions are characterized by disturbances in the expression of these receptors, in this study, we investigated their expression in ovarian cancers (OCs), as well as explored the phenotypic effects of vitamin D hydroxyderivatives and RORγ/α agonists on OC cells. The VDR and RORγ showed both a nuclear and a cytoplasmic location, and their expression levels were found to be reduced in the primary and metastatic OCs in comparison to normal ovarian epithelium, as well as correlated to the tumor grade. This reduction in VDR and RORγ expression correlated with a shorter overall disease-free survival. VDR, RORγ, and RORα were also detected in SKOV-3 and OVCAR-3 cell lines with increased expression in the latter line. 20-Hydroxy-lumisterol3 (20(OH)L3) and synthetic RORα/RORγ agonist SR1078 inhibited proliferation only in the OVCAR-3 line, while 20-hydroxyvitamin-D3 (20(OH)D3) only inhibited SKOV-3 cell proliferation. 1,25(OH)2D3, 20(OH)L3, and SR1078, but not 20(OH)D3, inhibited spheroid formation in SKOV-3 cells. In summary, decreases in VDR, RORγ, and RORα expression correlated with an unfavorable outcome for OC, and compounds targeting these receptors had a context-dependent anti-tumor activity in vitro. We conclude that VDR and RORγ expression can be used in the diagnosis and prognosis of OC and suggest their ligands as potential candidates for OC therapy.

Down-regulated HDAC3 elevates microRNA-495-3p to restrain epithelial-mesenchymal transition and oncogenicity of melanoma cells via reducing TRAF5

MicroRNAs (miRNAs) are emerging biomarkers in biological processes and the role of miR‐495‐3p has been identified in melanoma, while the detailed molecular mechanisms remain to be further explored. We aim to explore the effect of histone deacetylase 3 (HDAC3) and miR‐495‐3p on epithelial‐mesenchymal transition (EMT) and oncogenicity of melanoma cells by regulating tumour necrosis factor receptor‐associated factor 5 (TRAF5). Levels of HDAC3, miR‐495‐3p and TRAF5 in melanoma tissues and pigmented nevus tissues were determined, and the predictive roles of HDAC3 and miR‐495‐3p in prognosis of melanoma patients were measured. The melanoma cells were screened and transfected with relative oligonucleotides and plasmids, and the expression of HDAC3, miR‐495‐3p and TRAF5, and phenotypes of melanoma cells were gauged by a series of assays. The relations between HDAC3 and miR‐495‐3p, and between miR‐495‐3p and TRAF5 were confirmed. HDAC3 and TRAF5 were increased while miR‐495‐3p was decreased in melanoma cells and tissues, and the low expression of miR‐495‐3p as well as high expression of HDAC3 indicated a poor prognosis of melanoma patients. Inhibited HDAC3 elevated miR‐495‐3p to suppress EMT and oncogenicity of melanoma cells by reducing TRAF5. HDAC3 particularly bound to miR‐495‐3p and TRAF5 was the target gene of miR‐495‐3p. Our results revealed that down‐regulated HDAC3 elevates miR‐495‐3p to suppress malignant phenotypes of melanoma cells by inhibiting TRAF5, thereby repressing EMT progression of melanoma cells. This study may provide novel targets for melanoma treatment.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

[Power station sun and hormone factory skin : A current assessment of the importance of vitamin D metabolism during human evolution and strategies for UV prevention]

The sun is of great importance for human health. One important reason for this is the production of vitamin D, endorphins and many other hormones by the skin due to stimulation by sunlight. Insufficient access to sunlight increases the risk for vitamin D deficiency, a pandemic which would affect more than one billion people worldwide and under which ca. 60% of the population in Germany would suffer. The skin has a unique position in vitamin D metabolism as elementary steps for vitamin D production take place here and it is furthermore a target organ for actions of vitamin D. Due to the many positive effects of the sun, a healthy balance must be found between UV protection to shield against skin cancer but also ensuring sufficient vitamin D production. For regulation of this fragile balance between photoprotection and vitamin D production, which has accompanied mankind throughout evolution, sunscreens are an integral part of the modern lifestyle, although critical reports on possible risks for their use have recently become more frequent. This article discusses the current state of knowledge on the importance of vitamin D metabolism in human skin and the use of sun creams.

An Update on Vitamin D Metabolism

Vitamin D is a steroid hormone classically involved in the calcium metabolism and bone homeostasis. Recently, new and interesting aspects of vitamin D metabolism has been elucidated, namely the special role of the skin, the metabolic control of liver hydroxylase CYP2R1, the specificity of 1α-hydroxylase in different tissues and cell types and the genomic, non-genomic and epigenomic effects of vitamin D receptor, which will be addressed in the present review. Moreover, in the last decades, several extraskeletal effects which can be attributed to vitamin D have been shown. These beneficial effects will be here summarized, focusing on the immune system and cardiovascular system.

The vitamin D receptor Taq I polymorphism is associated with reduced VDR and increased PDIA3 protein levels in human intestinal fibroblasts

The synonymous single nucleotide polymorphism (SNP) rs731236, located in the vitamin D receptor (VDR) gene (Taq I) has been associated with both decreased levels of the protein in peripheral blood mononuclear cells and a fibrosis-related complication in Crohn´s disease (CD). Interactions between VDR and a protein-disulfide isomerase-associated 3 (PDIA3) in the regulation of extracellular matrix have been reported and we aim to analyze the relevance of the VDR genotypes and the effects of Vitamin D (VD) in the expression of VDR, PDIA3 and proliferation of intestinal fibroblasts. Human intestinal fibroblasts were isolated from the non-affected surgical resections of colorectal patients and classified according to the VDR genotype. In some cases, cells were transfected with specific PDIA3 siRNA. Basal and VD-stimulated expression of VDR, PDIA3 and Collagen 1A1 (COL1A1) as well as fibroblast migration/proliferation were analyzed. Our data show that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited lower VDR protein levels and higher proliferation than cells homozygous for the T allele. VD increased VDR and attenuated the accelerated proliferation of CC fibroblasts. The diminished VDR level detected in CC cells was associated with increased levels of both PDIA3 and COL1A1 expression and the transient silencing of PDIA3 significantly reduced COL1A1 expression. We conclude that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited: reduced VDR protein levels, increased proliferation and increased PDIA3/COL1A1 expression. Treatment with VD increased VDR and attenuated proliferation of these cells.

Obtaining and Investigation of the β-Cyclodextrin Inclusion Complex with Vitamin D 3 Oil Solution

Background. The research results of fat-soluble vitamin D 3 (cholecalciferol) encapsulation with β-cyclodextrin have been presented in this work. The vitamin D 3 inclusion complex with β-cyclodextrin was obtained under microwave radiation. The surface morphology of obtained clathrate inclusion complexes was described with the help of a scanning electron microscope. The thermographic measurement results on a differential scanning calorimeter have been presented. The activation energy of the β-cyclodextrin : vitamin D 3 clathrate complex thermal oxidative destruction reaction was calculated. The clathrate thermal destruction kinetic parameters were determined. The inclusion complex spectral properties were characterized by IR-Fourier and 1H and 13C NMR spectroscopy. The existence of β-cyclodextrin inclusion complex with vitamin D 3 in a 2 : 1 ratio was confirmed by the experimental results. The activation energy of thermal destruction of the inclusion complex of β-cyclodextrin with vitamin D 3 was calculated using four different methods.

Role of vitamin D3 in selected malignant neoplasms

Vitamin D₃ is a fat-soluble essential nutrient that affects multiple biologic functions in the organism through calcitriol and the vitamin D₃ receptor. This review article focuses on the results of studies on the relationship between the level of vitamin D₃ and cancer incidence or mortality, but also on the anticancer properties of vitamin D₃ that support its significant role in the prevention, clinical course, and overall survival rates of selected cancers (colorectal, prostate, breast, ovarian, endometrial, bladder, and malignant melanoma). The mechanisms of vitamin D₃ action involve, among others, polymorphism of vitamin D₃ receptor, cell cycle, caspases, and cancer stem cells. The level of vitamin D₃ has been also demonstrated to serve as a biomarker in some cancers, and high levels of vitamin D₃ can be conducive to successful cancer therapy.

MicroRNA-21-Enriched Exosomes as Epigenetic Regulators in Melanomagenesis and Melanoma Progression: The Impact of Western Lifestyle Factors

DNA mutation-induced activation of RAS-BRAF-MEK-ERK signaling associated with intermittent or chronic ultraviolet (UV) irradiation cannot exclusively explain the excessive increase of malignant melanoma (MM) incidence since the 1950s. Malignant conversion of a melanocyte to an MM cell and metastatic MM is associated with a steady increase in microRNA-21 (miR-21). At the epigenetic level, miR-21 inhibits key tumor suppressors of the RAS-BRAF signaling pathway enhancing proliferation and MM progression. Increased MM cell levels of miR-21 either result from endogenous upregulation of melanocytic miR-21 expression or by uptake of miR-21-enriched exogenous exosomes. Based on epidemiological data and translational evidence, this review provides deeper insights into environmentally and metabolically induced exosomal miR-21 trafficking beyond UV-irradiation in melanomagenesis and MM progression. Sources of miR-21-enriched exosomes include UV-irradiated keratinocytes, adipocyte-derived exosomes in obesity, airway epithelium-derived exosomes generated by smoking and pollution, diet-related exosomes and inflammation-induced exosomes, which may synergistically increase the exosomal miR-21 burden of the melanocyte, the transformed MM cell and its tumor environment. Several therapeutic agents that suppress MM cell growth and proliferation attenuate miR-21 expression. These include miR-21 antagonists, metformin, kinase inhibitors, beta-blockers, vitamin D, and plant-derived bioactive compounds, which may represent new options for the prevention and treatment of MM.

Detection of 7-Dehydrocholesterol and Vitamin D3 Derivatives in Honey

20(S)-Hydroxyvitamin D3 (20(OH)D3) is an endogenous metabolite produced by the action of CYP11A1 on the side chain of vitamin D3 (D3). 20(OH)D3 can be further hydroxylated by CYP11A1, CYP27A1, CYP24A1 and/or CYP27B1 to several hydroxyderivatives. CYP11A1 also hydroxylates D3 to 22-monohydroxyvitamin D3 (22(OH)D3), which is detectable in the epidermis. 20-Hydroxy-7-dehydrocholesterol (20(OH)-7DHC) has been detected in the human epidermis and can be phototransformed into 20(OH)D3 following the absorption of ultraviolet B (UVB) energy by the B-ring. 20(OH)D3 and its hydroxyderivatives have anti-inflammatory, pro-differentiation and anti-proliferative effects, comparable to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Since cytochromes P450 with 20- or 25-hydroxylase activity are found in insects participating in ecdysone synthesis from 7-dehydrocholesterol (7DHC), we tested whether D3-hydroxyderivatives are present in honey, implying their production in bees. Honey was collected during summer in the Birmingham area of Alabama or purchased commercially and extracted and analyzed using LC-MS. We detected a clear peak of m/z = 423.324 [M + Na]+ for 20(OH)D3 corresponding to a concentration in honey of 256 ng/g. We also detected peaks of m/z = 383.331 [M + H - H2O]+ for 20(OH)-7DHC and 25(OH)D3 with retention times corresponding to the standards. We further detected species with m/z = 407.329 [M + Na]+ corresponding to the RT of 7DHC, D3 and lumisterol3 (L3). Similarly, peaks with m/z = 399.326 [M + H - H2O]+ were detected at the RT of 1,25(OH)2D3 and 1,20-dihydroxyvitamin D3 (1,20(OH)2D3). Species corresponding to 20-monohydroxylumisterol3 (20(OH)L3), 22-monohydroxyvitamin D3 (22(OH)D3), 20,23-dihydroxyvitamin D3 (20,23(OH)2D3), 20,24/25/26-dihydroxyvitamin D3 (20,24/25/26(OH)2D3) and 1,20,23/24/25/26-trihydroxyvitamin D3 (1,20,23/24/25/26(OH)3D3) were not detectable above the background. In conclusion, the presence of 7DHC and D3 and of species corresponding to 20(OH)-7DHC, 20(OH)D3, 1,20(OH)2D3, 25(OH)D3 and 1,25(OH)2D3 in honey implies their production in bees, although the precise biochemistry and photochemistry of these processes remain to be defined.

Photoprotective Properties of Vitamin D and Lumisterol Hydroxyderivatives

We have previously described new pathways of vitamin D3 activation by CYP11A1 to produce a variety of metabolites including 20(OH)D3 and 20,23(OH)2D3. These can be further hydroxylated by CYP27B1 to produce their C1α-hydroxyderivatives. CYP11A1 similarly initiates the metabolism of lumisterol (L3) through sequential hydroxylation of the side chain to produce 20(OH)L3, 22(OH)L3, 20,22(OH)2L3 and 24(OH)L3. CYP11A1 also acts on 7-dehydrocholesterol (7DHC) producing 22(OH)7DHC, 20,22(OH)27DHC and 7-dehydropregnenolone (7DHP) which can be converted to the D3 and L3 configurations following exposure to UVB. These CYP11A1-derived compounds are produced in vivo and are biologically active displaying anti-proliferative, anti-inflammatory, anti-cancer and pro-differentiation properties. Since the protective role of the classical form of vitamin D3 (1,25(OH)2D3) against UVB-induced damage is recognized, we recently tested whether novel CYP11A1-derived D3- and L3-hydroxyderivatives protect against UVB-induced damage in epidermal human keratinocytes and melanocytes. We found that along with 1,25(OH)2D3, CYP11A1-derived D3-hydroxyderivatives and L3 and its hydroxyderivatives exert photoprotective effects. These included induction of intracellular free radical scavenging and attenuation and repair of DNA damage. The protection of human keratinocytes against DNA damage included the activation of the NRF2-regulated antioxidant response, p53-phosphorylation and its translocation to the nucleus, and DNA repair induction. These data indicate that novel derivatives of vitamin D3 and lumisterol are promising photoprotective agents. However, detailed mechanisms of action, and the involvement of specific nuclear receptors, other vitamin D binding proteins or mitochondria, remain to be established.

Antiproliferative activity of side-chain truncated vitamin D analogs (PRI-1203 and PRI-1204) against human malignant melanoma cell lines

Vitamin D compounds are versatile molecules widely considered as promising agents in cancer prevention and treatment, including melanoma. Previously we investigated series of double point modified vitamin D₂ analogs as well as non-calcemic 20S-hydroxyvitamin D₃ and 21-hydroxypregnacalciferol as to their anti-melanoma activity. Surprisingly, short side-chain vitamin D analogs were found to be biologically active compounds. Thus, here we tested novel derivatives of pregnacalciferol with an additional hydroxyl at the end of the truncated side chain, PRI-1203 and PRI-1204, as to their potency against human melanoma A375 and RPMI7951 cell lines. Tested compounds are geometric isomers, with 19-methylene positioned in PRI-1203 like in a calcitriol molecule, but reversed in the PRI-1204 analog to the (5E,7E) geometry (5,6-trans). We noticed a decrease in cells viability exerted by PRI-1203. The antiproliferative effect of PRI-1204 was very low, emphasizing the importance of the natural 19-methylene geometry in the PRI-1203. PRI-1203 was also effective in inhibition of A375 melanoma cells migration. PRI-1203, but not PRI-1204, increased the percentage of A375 and RPMI7951 melanoma cells in the G0/G1 phase of cell cycle, possibly in a p21 and p27 independent manner. Both, analogs have very low effect on the level of CYP24A1 mRNA, in comparison to active form of vitamin D - 1.25(OH)2D3. In addition, both tested compounds failed to elicit VDR translocation to the nucleus. Thus, it could be postulated that side chain shortening strongly affects binding of analogs to VDR and activation of genomic responses, however do not impair their antiproliferative activities.

Current Molecular Markers of Melanoma and Treatment Targets

Melanoma is a deadly skin cancer that becomes especially difficult to treat after it metastasizes. Timely identification of melanoma is critical for effective therapy, but histopathologic diagnosis can frequently pose a significant challenge to this goal. Therefore, auxiliary diagnostic tools are imperative to facilitating prompt recognition of malignant lesions. Melanoma develops as result of a number of genetic mutations, with UV radiation often acting as a mutagenic risk factor. Novel methods of genetic testing have improved detection of these molecular alterations, which subsequently revealed important information for diagnosis and prognosis. Rapid detection of genetic alterations is also significant for choosing appropriate treatment and developing targeted therapies for melanoma. This review will delve into the understanding of various mutations and the implications they may pose for clinical decision making.