[Potential of Using Vitamin D as an Adjuvant Treatment of Malignant Melanoma]. / Potenciál vitamínu D v adjuvantnej liecbe malígneho melanómu koze.

The incidence of malignant melanoma worldwide continues to grow despite the enormous advances in topical and systemic therapy. This increase is recorded regularly even in countries where, as a result of public health campaigns, dermatological examination and subsequent treatment have become more frequent. However, there have been reports of a stable or even decreasing mortality rate that seem to contradict the objective increase in its incidence. The well-known risk factors for malignant melanoma include sunburns and occasional sunbathing, whereas regular sunbathing is associated with a lower incidence. Besides DNA damage, exposure to the sun also results in the synthesis of vitamin D (cholecalciferol) in the skin, which contributes to over 90% of circulating Calcidiol (25 (OH) D) in serum. Current cultural norms (dressing, working indoors, avoiding sun exposure, and dietary choices) affect the serum vitamin D level, resulting in severely low serum levels of vitamin D in some sectors of todays society. Emerging data suggests that mild, unprotected exposure to UV radiation or dietary supplementation with oral vitamin D can reduce cancer mortality. Supplementation with vitamin D or alternatively UV exposure may be regarded as an adjuvant for the treatment of many types of tumors (e.g. tumors of the colon, prostate, and breast). The effect of vitamin D on malignant melanoma may be due to its non-calcemic systemic effects. Additionally, vitamin D may have more pronounced effects locally in the skin because of the unique ability of keratinocytes to synthesize the active form of vitamin D.Key words: malignant melanoma - vitamin D - adjuvant treatment therapy - clinical oncology The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 7. 10. 2016Accepted: 26. 7. 2017.

Current knowledge on the active form of Vitamin D synthesized in the skin and its effects on malignant melanoma.

The link between sunlight and skin cancer is a frequently discussed topic. However, ultraviolet radiation also induces the production of Vitamin D in the body. Keratinocytes and their ability to synthesize the active form of Vitamin D, which is consumed at the place of its origin in the skin, have a unique place in this discussion. We observe a remarkable sunshine-related paradox when we monitor the relationship between the dose of solar radiation and one type of skin cancer - malignant melanoma. Recent knowledge of the non-calcemic effects of Vitamin D, which include growth regulation, DNA repair, differentiation, apoptosis, membrane transport, metabolism, cell adhesion and oxidative stress, could help to further clarify this relationship. In this context, adjuvant Vitamin D therapy is currently being considered in patients with malignant melanoma, and this is expected to reduce tumor invasiveness and micrometastases and thus improve patient prognosis and reduce the risk of relapse.

[The Importance of MITF Signaling Pathway in the Regulation of Proliferation and Invasiveness of Malignant Melanoma]. / Význam signálnej dráhy MITF pri regulácii proliferácie a invazivity malígneho melanómu.

BACKGROUND: Malignant melanoma is one of the most aggressive types of cancers. Melanoma is derived from pigment-producing cells, melanocytes, which are characterized by a specific survival mechanism. Microphthalmia-associated transcription factor (MITF-M) plays a role in the metabolism of melanoma and is involved in the regulation of the expression of multiple genes mediating processes such as melanogenesis, proliferation, differentiation, and melanocyte survival. The expression of this transcription factor in melanocytes is activated by several signaling pathways, and reduced expression or function of MITF-M can cause the dysregulation of anti-apoptotic mechanisms. MITF-M is also involved in matrix metalloproteinase 14 (MMP14) activity, which is responsible for shape changes in melanocytes and increases in their motility and invasiveness. Very low levels of expression of MITF-M are found in human melanocytes with an invasive phenotype, indicating that this transcription factor acts as a suppressor of the metastatic process. Cancer cells with low expression of cytosolic/nuclear ß-catenin have a small amount of MITF-M 14 that is insufficient to inhibit MMP transcription. The enzyme catalyzes the degradation of laminin and fibronectin, thereby changing the shape of melanocytes, which leads to their increased mobility and invasiveness. AIMS: This review describes the regulatory pathway of MITF-M activation, its involvement in the proliferation of transformed melanocytes, and its role in increasing the invasiveness of malignant melanoma. A detailed understanding of the MITF-M signaling pathway is highly topical and could help to develop new diagnostic and therapeutic applications for patients with malignant melanoma.Key words: neoplastic cell transformation - melanoma - MITF transcription factorThis work was supported by grant projects VEGA 1/0115/14 and VEGA 1/0873/16.The authors declare they have no potential confl icts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 4. 12. 2015Accepted: 14. 6. 2016.