Protective Effect of Topical Vitamin D3 against Photocarcinogenesis in a Murine Model.
BACKGROUND
Although the incidence of non-melanoma skin cancer is increasing, there are no effective practical preventive measures other than avoiding sun exposure.


OBJECTIVE
To elucidate the protective effect of topical application of biologically active vitamin D3 (calcitriol) on skin cancer development caused by exposure to ultraviolet (UV).


METHODS
Groups of hairless mice were topically treated with either calcitriol or vehicle immediately after exposure to UVB and UVA three times weekly for the initial 20 weeks, and without UV exposure in the following 6 weeks. Tumor number was counted and biopsies were done for histopathologic analysis. The changes of cyclobutane pyrimidine dimer (CPD) were evaluated 1 hour and 11 hours after short term of UV exposure and application of calcitriol. For safety evaluation, blood test and body weights were evaluated at 23rd and 25th week.


RESULTS
Total tumor count and number of tumors less than 3 mm in size tended to be fewer in calcitriol group, and tumors more than 3 mm in size showed significantly lower tumor formation rate in calcitriol group. Single application of calcitriol reduced CPD at 1 hour and 11 hours after UV exposure. Histopathologic analysis showed tumors with lower grade malignancy in calcitriol group which suggested a delay in tumor progression. However, serum levels of calcium and phosphate in calcitriol group were above normal range, and weight loss was found.


CONCLUSIONS
Topical calcitriol may suppress the formation and progression of UV-induced non-melanoma skin cancer by enhancing the repair mechanism of UV damage.
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Ji Seok
JS
Kim
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Minyoung
M
Jung
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Jiyeon
J
Yoo
Department of Dermatology, Yonsei University Wonju College of Medicine, Wonju, Korea.
Eung Ho
EH
Choi
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Byung Cheol
BC
Park
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Myung Hwa
MH
Kim
Department of Dermatology, Dankook University College of Medicine, Cheonan, Korea.
Seung Phil
SP
Hong
1,25-dihydroxyvitamin D; Calcitriol; Carcinogenesis; Skin neoplasm