A Protein That Prevents Some Cancers But Promotes Sun-Induced Skin Cancer

A new study show that the protein SIRT6 not only inhibit
growth of liver and colon cancer, but also promote the
development of skin cancer.
A new study published in Cancer Research shows SIRT6, a protein known to inhibit the growth of liver and colon cancers, can promote the development of skin cancers by turning on an enzyme that increases inflammation, proliferation and survival of sun-damaged skin cells.
 
Previously considered protective, SIRT6 is part of a family of seven proteins called sirtuins that help regulate genomic stability and prevent some of the genetic flaws associated with aging. SIRT6 helps repair DNA damage, which can lead to cancer. This study reveals its activity can vary from one tissue type to another.
 
To understand how SIRT6 contributed to the onset of skin cancer the researchers looked at its effects on COX-2, an enzyme responsible for inflammation. COX-2 also promotes cell proliferation and survival, however, two hallmarks of cancer cells. When the researchers increased expression of SIRT6, COX-2 became more abundant. When they inhibited SIRT6 expression, COX-2 levels decreased.
 
They also found that exposure to ultraviolet-B light, a cancer-causing component of sunshine, could trigger increased expression of SIRT6 in skin cells. This led to the production of COX-2, which contributed to the development of skin cancers.
 
The findings underscore a critical role for SIRT6 in the skin damage cause by ultraviolet light, and adds to the understanding of the mechanisms of skin carcinogenesis. It suggests that SIRT6 could provide a useful target for cancer prevention.