Assessing PFOS Toxicity and Carcinogenicity Through Zebrafish Xenograft Assays

Persistent environmental pollutants such as per- and poly-fluoroalkyl substances (PFAS) have been associated with a wide range of toxic effects, including cancer. There are over 12,000 PFAS compounds, which may act as carcinogens individually or in combinations. Therefore, efficient in vivo models of carcinogenicity are needed for evaluating environmental contaminant compounds and chemical mixtures. Here, we use the larval zebrafish xenograft assay to identify tumor growth activity of perfluorooctanesulfonic acid (PFOS), a known carcinogenic PFAS. Dose response curves for PFOS exposure were used to identify the Maximum Tolerated Concentration (MTC) and Lethal Concentration causing 50% death (LC50) under xenograft conditions. Zebrafish xenografts were established by injecting fluorescently labeled kidney cancer cells into the embryonic body cavity near the developing kidney, followed by treatment with PFOS at a concentration of 5%, 10% and 20% of the MTC. When treated with PFOS, zebrafish xenografts using renal cell carcinoma (ACHN) cells and clear renal cell carcinoma (Caki-1) cells show dose-dependent changes in tumor area. This study is the first to directly show cancer-promoting activity of a PFAS, using a rapid in vivo zebrafish xenograft assay, and demonstrates the utility of this model for validation of predicted cancer-promoting properties of environmental contaminants.