Schlumpf Margret, Reichrath Jörg, Lehmann Bodo, Sigmundsdottir Hekla, Feldmeyer Laurence, Hofbauer Günther Fl, Lichtensteiger Walter
GREEN Tox and University of Zürich; Institute of Anatomy; Zürich, Switzerland.
Dermatoendocrinol. 2010 Jan;2(1):19-25. doi: 10.4161/derm.2.1.12016.
Since exposure to sunlight is a main factor in the development of non-melanoma skin cancer and there are associations between malignant melanoma and short-term intense ultraviolet (UV) exposure, particularly burning in childhood, strict protection from UV-radiation is recommended. However, up to 90% of all requisite vitamin D has to be formed within the skin through the action of the sun-a serious problem, for a connection between vitamin D deficiency, demonstrated in epidemiological studies, and various types of cancer and other diseases has been confirmed. A UVB-triggered skin autonomous vitamin D(3) synthesis pathway has recently been described, producing the active Vitamin D metabolite calcitriol. This cutaneous vitamin D(3) pathway is unique. Keratinocytes and dendritic cells can convert vitamin D to calcitriol. Cutaneous T cells activated in the presence of calcitriol express the chemokine receptor CCR10 attracting them to the chemokine CCL27 that keratinocytes express selectively in the epidermis, and migrate from dermal layers of the skin to the epidermis under UV radiation. Thus, calcitriol has endocrine roles beyond its calciotropic action, including cell growth and cancer prevention. Therefore, strict sun protection procedures to prevent skin cancer may induce the risk of vitamin D deficiency. As there is evidence that the protective effect of less intense solar radiation can outweigh its mutagenic effect, better balanced approaches to sun protection should be sought.
由于暴露于阳光是非黑色素瘤皮肤癌发病的主要因素，且恶性黑色素瘤与短期强烈紫外线（UV）暴露之间存在关联，尤其是儿童时期的晒伤，因此建议严格防护紫外线辐射。然而，所有必需维生素D的90%必须通过阳光作用在皮肤内形成——这是一个严重问题，因为流行病学研究已证实维生素D缺乏与各类癌症及其他疾病之间存在关联。最近描述了一种UVB触发的皮肤自主维生素D(3)合成途径，可产生活性维生素D代谢物骨化三醇。这种皮肤维生素D(3)途径是独特的。角质形成细胞和树突状细胞可将维生素D转化为骨化三醇。在骨化三醇存在的情况下被激活的皮肤T细胞表达趋化因子受体CCR10，吸引它们向角质形成细胞在表皮中选择性表达的趋化因子CCL27移动，并在紫外线辐射下从皮肤的真皮层迁移至表皮。因此，骨化三醇除了其钙调节作用外，还具有内分泌作用，包括细胞生长和癌症预防。所以，预防皮肤癌的严格防晒措施可能会引发维生素D缺乏的风险。鉴于有证据表明强度较低的太阳辐射的保护作用可能超过其诱变作用，应寻求更好的平衡防晒方法。
