Estrogen receptor β (ERβ) has been reported to impede cancer metastasis while estrogen receptor α (ERα) can promote cancer metastasis. Several splice variants of ERβ exist in humans and they may have different functions in different tissues, but the role of these differently spliced isoforms in cancer metastasis has not been well studied. Various model systems such as xenografting of cancer cells in mice and dogs have been used to study cancer metastasis. However, difficulties in monitoring living cancer cell metastasis in large non-transparent animals have been a limitation in these studies. Zebrafish embryos are transparent and their immune system is not fully developed until several days after post fertilization. These features make zebrafish a useful model for xenografting cancer cells and monitoring their migration. In addition, the large number of offspring and small size of the embryos make the zebrafish model amendable for high throughput screening and anti-metastasis drug discovery. In our studies, we co-microinjected breast cancer cell lines bearing ERβ constructs or control constructs, expressing fluorescent proteins of different colors, into zebrafish embryos at 48 hours post fertilization (hpf). After 2 hours recovery, fish embryos with cells circulating in the blood system were removed. Embryos that contained cells only in the original injection sites were incubated at 32°C to monitor the cancer cell migration daily using a fluorescence microscope. We found that ERβ expressing breast cancer cells were less migratory than the control cells and they remained at the original injection site to a large extent. We also examined the metastasis of prostate cancer cell lines expressing ERβ splice variants in our zebrafish xenograft model and found that cells with different ERβ splice variants exhibited different migration patterns. In conclusion, zebrafish embryos work as an effective model for studying the role of ERβ and its splice variants for cancer metastasis of diverse cancer cell lines.

Citation Format: Ruixin Hao, Christoforos Thomas, Prasenjit Dey, Anders Ström, Catherine W. McCollum, Fotis Nikolos, Maria Bondesson, Jan-Ake Gustafsson. Zebrafish embryos as a model for studying the role of estrogen receptor β in cancer metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1575. doi:10.1158/1538-7445.AM2013-1575