UV radiations from sunlight as a potential carcinogen for the development of skin malignancy: A review of the current status and future prospects
Afifa Zaeem 1, Muhammad Sultan Abbasi 1, Ayesha Maqbool 2, Masroor Ellahi Babar 2, Tanveer Hussain 2*
a Department of Biotechnology, Virtual University of Pakistan, Lahore-Pakistan
b Department of Molecular Biology, Virtual University of Pakistan, Lahore-, Pakistan
Sunlight filtered ultraviolet (UV) radiations are one of the most expected reason of skin malignancy. The intensity of photo-damage to skin, caused by the UV radiations varies with their type (UVA, UVB, and UVC). Human skin has developed a natural defense mechanism for protection against harmful UV radiations by producing vitamin D but climatic change and ozone depletion are the top most factors contributing towards excessive UV filtrations into the earth surface. These excess UV radiations result in two main types of skin cancers, melanoma and non-melanoma skin cancers (NMSCs). Additionally, UV radiations mainly contribute towards immunosuppression by inhibiting immune system. Photo-aging and photo-carcinogenesis are the consequences of immunosuppression. Other major effects of UV exposure include DNA damage and deregulation of p53 protein. Oxidative DNA damage by UV rays can result in the formation of pyrimidine dimers by photochemical reactions. The most common photoproduct is cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts, which are primary cause of skin malignancies. Nucleotide excision repair mechanism is used to repair DNA damages by excising CPDs in surrounding regions. Lastly, various remedies and preventive measures are introduced in market for skin protection to avoid DNA damages, especially nanotechnology-based sunscreens. Nanoparticles of zinc oxide (ZnO) and titanium oxide (TiO2) have unique properties to filter the UV radiations, thus act more efficiently for skin protection as compared to their conventional particles. Therefore, public awareness about harmful effects of UV radiations and use of nanoparticles containing sunscreens should be promoted to prevent the cases of skin anomalies. This review is aimed at summarizing all the aspects of UV radiations related to skin cancer including the types of UV, resulting DNA damage, photo-immunology and preventive measures.