A novel goldfish orthotopic xenograft model of hepatocellular carcinoma developed to evaluate antitumor drug efficacy

Tumor xenograft animal models play a crucial role in hepatocellular carcinoma (HCC) research. Mice xenograft models are time consuming, laborious and expensive while zebrafish tumor xenograft models are cost-effective and effortless. However, the development of orthotopic xenograft models for HCC in zebrafish embryos has been challenging due to the small size of zebrafish livers. In this study, we utilized 7-day-old goldfish embryos as hosts and successfully established an orthotopic xenograft model of HCC in goldfish livers. Through injecting fluorescence labeled HCC cells into the liver of goldfish, we could visualize the proliferation and migration of tumor cells in vivo. In addition, we found that the temperature of 36 °C was better for tumor cell survival in goldfish larvae compared to 28 °C, assessed by EdU and TUNEL assays. Moreover, macrophage infiltration in the goldfish liver could be evaluated by neutral red staining. Finally, we evaluated the efficacy of the targeted therapy drug Sorafenib and the traditional Chinese medicine, Huaier granules, alone or in combination in the goldfish HCC orthotopic xenograft model. We found that the combination therapy showed the best efficacy against HCC cells in terms of macrophage infiltration, polarization as well as tumor cells proliferation, metastasis and apoptosis. In conclusion, the proposed goldfish HCC orthotopic xenograft model opens new avenues for HCC related research, including evaluation of tumor progression, cell interactions in the immune microenvironment, drug efficacy, and screening of anti-tumor drugs.