(432a) Agnps: Silver Bullets for Skin Cancer Chemoprevention

Each year, over two million new cases of skin cancer are diagnosed, which is greater than the combined incidence of cancers of the breast, prostate, lung and colon. Therefore, prevention of skin cancer from the harmful effects of UV remains a priority area of research. One approach to protect against UV is to use sunscreen lotion as a direct barrier on the skin. Sunscreens are formulated to contain UV filters or reflectors such as zinc oxide and titanium dioxide nanoparticles. Several studies have shown the inflammatory/toxic effects of these nanoparticles in normal skin cells. Therefore, it is necessary to consider the efficacy of novel nanoparticles in skin cancer prevention as well as new methods to synthesize these nanoparticles. There are no studies detailing the effect of silver nanoparticles (AgNPs) on normal human skin cells or skin cancer cells. It is also not known if AgNPs play a chemopreventive role against UV-induced skin carcinogenesis.  

In this project, the effect of AgNPs on skin epidermal immortalized, non-tumorigenic keratinocytes (HaCaT) and epidermoid carcinoma skin cancer cells (A431-NS) was tested. A chemical method was successfully utilized for the production of silver nanoparticles. The effect of size and concentration of AgNPs was tested for both skin cancer therapy as well as skin cancer chemoprevention against UV-induced cell damage. It was shown that AgNPs at the size range 10-100 nm and concentration range 1-10 mg/L are not toxic to non-tumorigenic HaCaT cells but are toxic to carcinoma A431-NS cells, thereby demonstrating the therapeutic effect of AgNPs. Dot blot analysis indicates that UV-induced DNA damage in HaCaT cells with AgNPs of size range 10 nm to 40 nm is significantly reduced. UV-induced apoptosis studies via FACS indicate that AgNPs in the size range 10-40 nm provide significant protection (4 fold) against UV-induced apoptosis, thereby demonstrating the chemopreventive effect of AgNPs.