At the Ohio State University Comprehensive Cancer Center, researchers have discovered that male mice had lower levels of an essential skin antioxidant and higher levels of certain-cancer linked inflammatory cells when compared with female mice.
The antioxidant is a protein called catalase which blocks skin cancer by soaking up hydrogen peroxide and other DNA-damaging reactive-oxygen compounds that are created on the skin as a result of ultraviolet B (UVB) exposure – the source of sunburn and cancer-causing skin damage. Other studies have found low catalase activity to be associated to skin cancer progression.
According to research co-leaders Gregory Leninski and Tatiana Oberyszyn, “The findings suggest that women may have more natural antioxidant protection in the skin than men. As a result, men may be more susceptible to oxidative stress in the skin, which may raise the risk of skin cancer in men compared to women.”
The study also revealed that UVB exposure led to a unique inflammatory white blood cell population called ‘myeloid-derived suppressor cells’ to migrating from the bone marrow into the exposed skin. Additionally, greater numbers of these cells moved into the skin of male mice compared to female mice.
First author, Nicholas Sullivan, adds, “To our knowledge, we’ve shown for the first time that UVB exposure causes a migration of systemic myeloid-derived suppressor cells, and it suggests that these cells might be a novel source of UVB-induced immune suppression.” This suggests that these UVB-induced inflammatory cells may contribute directly with the formation of skin tumors and possibly other tumors rather than just aiding cancer progression, as generally thought, Sullivan notes.
The researchers conducted their study by using a strain of hairless mice that develops squamous cell carcinoma of the skin – the second most common skin cancer in humans – when exposed to UVB. The investigators also found that applying a topical form of catalase to the mice blocked the migration of the suppressor cells into UVB-exposed skin, indicating that the influx of these cells in males might be a result of the lower skin-catalase activity.
Their study results indicated that male mice with UVB-induced skin tumors had 55 percent more of the suppressor cells in the skin than their female counterparts. The authors conclude, “Men face a higher risk of numerous types of cancer, and relatively higher levels of inflammatory myeloid cells might contribute to this susceptibility.”