Gold nanoparticles enhance radiation sensitization and suppress colony formation in a feline injection site sarcoma cell line, in vitro

Injection Site Sarcomas (ISS) are highly invasive feline malignant tumors that are frequently associated with routine vaccination. Current treatment modalities include chemotherapy, radiation, and radical surgery. ISS have been shown to be one of the most treatment resistant of feline cancers with high rates of recurrence. Previous studies have shown that gold and other high atomic number nanoparticles have the ability to increase the dose of radiation deposited into tissue by generating secondary electrons. The focus of the current study was to assess the effects of gold nanoparticles (AuNP) on ISS cytotoxicity and colony formation both as a standalone treatment and in combination with electron beam radiation. Cells from an established ISS cell line were co-cultured with 15 nm AuNP at 0.0, 0.25, 0.5, 1.0, 2.0 and 4.0 mM. AuNP cytotoxicity was evaluated by assessing changes in cellularity, cell proliferation, cell cycle and viability/apoptosis/necrosis. The radiosensitizing potential of AuNP on ISS replication was assessed by the clonogenic assay. AuNP were found to significantly decrease cellular proliferation. However, the acute viability and cell cycle of ISS was not significantly altered. Interestingly, AuNP alone were shown to significantly impair colony formation. In the presence of 9 MeV electron radiation, AuNP numerically decreased colony formation in ISS cells compared to cells treated with radiation only. AuNP may have efficacy as a long term therapeutic agent for decreasing ISS growth.