The avian embryo is a classic model organism for developmental studies, and is an emerging model for studying the biology of cancer epithelial-to-mesenchymal transition (EMT) due to molecular similarities of EMT in cancer and development. In recent studies, human neuroblastoma and melanoma cell lines have been injected into the neural tube of embryos and their behaviour tracked, as these cancer lineages share similar characteristics to the neural crest cells that migrate from the neural tube during embryogenesis. However, to our knowledge no study has utilised the quail embryo to investigate human breast cancer cell survival or behaviour. Our aim was to explore the suitability of the quail embryo for the study of breast cancer biology, specifically migration and survival of disseminated cells. Preliminary implantation experiments indicated that the quail embryo selectively hosted some of the cell lines Fluorescently tagged mesenchymal (MDA-MB-231-GFP) or epithelial (MDA-MB-468-GFP) cell lines were detected four days post-implantation, however the mesenchymal PMC42-ET and PMC42-LA cells lines were no longer detectable as early as two days post-implantation.
Our second aim was to assess the impact microRNAs (miRNAs) have on endogenous developmental EMT in the quail embryo. Plasmid DNA constructs designed to overexpress human miR-29a and miR-200c were electroporated into the neural crest region of embryos. Both microRNAs caused a reduction in migration of neural-tube derived crest-like cells (compared to control empty plasmid electroporations).
In conclusion, our preliminary data i) show the embryo method is suitable for short term experiments only, primarily because of the rapid growth of the embryos, ii) support the hypothesis that the quail embryo is a suitable host for some human breast cancer cell lines, but with previously unsuspected cell-line differences, and iii) show the quail embryo is a useful model for testing miRNA function in complex tissue environments, because of the cross-species conservation of miRNAs.