Oral Presentation 18th International Congress on Photobiology 2024

Protection of vitamin D compounds against UV-induced skin carcinogenesis (#19)

Katie Dixon 1 2 3
  1. School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, NSW, Australia
  2. Faculty of Veterinary Sciences, University of Sydney, Sydney, NSW, Australia
  3. Discipline of Anatomy and Histology, Bosch Institute, University of Sydney, Sydney, NSW, Australia

Australia has one of the highest rates of skin cancer globally, with two in three people being diagnosed by the age of 70. Whilst non-melanoma skin cancers are more common, melanoma is responsible for the majority of skin cancer-related deaths. The main contributors to ultraviolet radiation (UV)-induced skin carcinogenesis are UV-induced DNA damage, some of which is inadequately repaired, resulting in mutations, and UV-induced immune suppression, which results in failure of recognition and elimination of developing skin tumours by immune surveillance. Another consequence of UV is the synthesis of vitamin D and its active metabolite, 1,25-dihydroxyvitamin D3 (1,25D) in skin cells. Epidemiological studies have linked vitamin D status to melanoma risk and outcome. Our studies have shown that the active vitamin D metabolite 1,25D and related compounds including 1,25-dihydroxylumisterol and tetrahydrocurcumin can inhibit UV-induced DNA damage, immune suppression and skin carcinogenesis. Phosphatase and tensin homolog (PTEN) and N-myc downstream regulated gene-1 (NDRG1) are proteins that are lost or suppressed during carcinogenesis and metastasis. We showed that levels of both these proteins are significantly reduced 24 h after UV in primary human skin cells and in Skh:hr1 mouse skin, but significantly increased with 1,25D treatment. We have also shown that 1,25D can increase levels of proteins that play a key role in nucleotide excision repair of UV-induced DNA damage. Our studies suggest a role for vitamin D compounds in the prevention of skin carcinogenesis and inhibition of melanoma cell growth. Vitamin D-like compounds that are less calcemic but photoprotective are promising for use in after-sun lotions to protect against acute UV damage while also preventing skin carcinogenesis.