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

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.

Clinical and genetic determinants of vitamin D receptor expression in cutaneous melanoma patients

Decrease of vitamin D receptor (VDR) expression is observed in melanocytic naevi and melanoma compared to normal skin. Little is known about factors influencing VDR expression in cutaneous melanoma (CM). We investigated the correlation of VDR expression in CM with 25-hydroxy vitamin D (25OHD) levels, demographic/clinical parameters, genetic variants of VDR and pathology of the primary tumor. Demographic/clinical parameters were recorded in 407 prospectively recruited CM patients of a multi-center controlled study (ViDMe trial). We determined VDR expression both in the nucleus and in the cytoplasm by semi-quantitative assessment in CM tissue using histochemistry in 279 patients, expressed in percentages and histoscore (H-score). Genomic DNA from 332 patients was extracted to genotype thirteen VDR single nucleotide polymorphisms (SNPs) using TaqMan. VDR expression in CM tissue from 279 patients was correlated with clinical/demographic parameters and 25OHD levels (univariable and multivariable analysis), VDR SNPs (univariable analysis) and pathology parameters of primary CM tissue (univariable analysis). Cytoplasmic VDR expression was increased in patients who stated to have a high sun exposure during their life compared to patients with low sun exposure (p H-score,univariable : 0.001, p H-score,multivariable : 0.004). The A allele of the genetic VDR polymorphism Fok1 was associated with a higher expression of the VDR in the cytoplasm (p cytoplasmic, univariable : 0.001 and p H-score, univariable : 0.02). In the primary tumor, presence of mitosis (p nucleus,%, univariable : 0.002) and perineural invasion (p nucleus,%,univariable : 0.03) were significantly associated with low nuclear VDR expression. ClinicalTrials.gov Identifier: NCT01748448.

Altitude Effect on Cutaneous Melanoma Epidemiology in the Veneto Region (Northern Italy): A Pilot Study

The incidence of cutaneous melanoma has been increasing in the last decades among the fair-skinned population. Despite its complex and multifactorial etiology, the exposure to ultraviolet radiation (UVR) is the most consistent modifiable risk factor for melanoma. Several factors influence the amount of UVR reaching the Earth’s surface. Our study aimed to explore the relationship between melanoma and altitude in an area with mixed geographic morphology, such as the Veneto region (Italy). We included 2752 melanoma patients who were referred to our centers between 1998 and 2014. Demographics, histological and clinical data, and survival information were extracted from a prospectively maintained local database. Head/neck and acral melanoma were more common in patients from the hills and the mountains, while limb and trunk melanoma were more common in patients living in plain and coastal areas. Breslow thickness, ulceration and mitotic rate impaired with increased altitude. However, the geographical area of origin was not associated with overall or disease-free survival. The geographical area of origin of melanoma patients and the “coast-plain-hill gradient” could help to estimate the influence of different sun exposure and to explain the importance of vitamin D levels in skin-cancer control.