Possible therapeutic role of short-chain fatty acids from skin commensal bacteria in UVB-induced skin carcinogenesis

Solar ultraviolet B (UVB) radiation is a major skin cancer-causing agent. Initiation, promotion, and progression are the diverse phases of UVB-induced carcinogenesis. Exposure to UVB causes abnormalities in a series of biochemical and molecular pathways: thymine dimer formation, DNA damage, oxidative stress, inflammatory responses, and altered cell signaling, eventually resulting in tumor formation. The increased skin cancer rates urge researchers to develop more efficient drugs, but synthetic chemotherapeutic drugs have more contrary effects and drug resistance issues, which have been reported recently. The current review focuses on the relationship between microbes and cancer. Human skin acts as a barrier against the external environment and serves as a protective shield for its inhabitant microbiota, collectively called skin microbes. The gut microbiome plays a vital role in cancer therapy. Production of short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate by intestinal microbes has anti-cancer properties against various cancer cell lines. Yet, the knowledge of SCFAs produced by skin microbes remains yet to be elucidated exhaustively. In this review, we strive to summarize the findings of studies performed to date regarding the anti-cancer properties of SCFA against various cancer cell lines and provide insight into future directions in the skin microbiome field.