In vitro efficacy of doxorubicin and etoposide against a feline injection site sarcoma cell line

• The cytologic effects of doxorubicin or etoposide were assessed alone or in combination on a feline injection site sarcoma (ISS) cell line.
• A positive correlation between cell cytotoxicity, drug concentration and time of drug addition was observed.
• ISS cells in G0/G1 were significantly reduced and those in G2/M were significantly increased following either drug treatment.
• Doxorubicin and etoposide alone and in combination differentially alter ISS cell viability and cycle.

Feline injection site sarcoma (ISS) is a locally invasive tumor, in which surgical treatment is frequently combined with radiation or chemotherapy to improve tumor control. The focus of this study was to evaluate the cytotoxic effects of doxorubicin or etoposide on a feline injection site sarcoma cell line (JB) and to assess the impact of combining these drugs on cell death and cell cycle. Both single agent and combination drug administration increased cell death and significantly reduced the number of viable cells. Cells in G0/G1 were significantly reduced while the G2/M fraction was significantly increased following treatment. Collectively, combining doxorubicin and etoposide at the lower EC yielded comparable results to the EC50 of either drug alone in degree of cytotoxicity, level of apoptosis, and % of cells in G2/M. The results of this study indicate that doxorubicin and etoposide alone and in combination differentially alter ISS cell viability and cycle.