Fascin-1 Promotes Cell Metastasis through Epithelial–Mesenchymal Transition in Canine Mammary Tumor Cell Lines

Canine mammary tumors (CMTs) are the most common type of tumor in female dogs. In this study, we obtained a metastatic key protein, Fascin-1, by comparing the proteomics data of in situ tumor and metastatic cell lines from the same individual. However, the role of Fascin-1 in the CMT cell line is still unclear. Firstly, proteomics was used to analyze the differential expression of Fascin-1 between the CMT cell lines CHMm and CHMp. Then, the overexpression (CHMm-OE and CHMp-OE) and knockdown (CHMm-KD and CHMp-KD) cell lines were established by lentivirus transduction. Finally, the differentially expressed proteins (DEPs) in CHMm and CHMm-OE cells were identified through proteomics. The results showed that the CHMm cells isolated from CMT abdominal metastases exhibited minimal expression of Fascin-1. The migration, adhesion, and invasion ability of CHMm-OE and CHMp-OE cells increased, while the migration, adhesion, and invasion ability of CHMm-KD and CHMp-KD cells decreased. The overexpression of Fascin-1 can upregulate the Tetraspanin 4 (TSPAN4) protein in CHMm cells and increase the number of migrations. In conclusion, re-expressed Fascin-1 could promote cell EMT and increase lamellipodia formation, resulting in the enhancement of CHMm cell migration, adhesion, and invasion in vitro. This may be beneficial to improve female dogs’ prognosis of CMT.