Human Fidgetin Modulates Cell Migration and EMT in Breast Cancer Cells

Epithelial-mesenchymal transition (EMT) and cell migration are two essential cellular processes involved in normal biological events such as embryogenesis, organ development, and wound healing, and are also associated with pathological conditions like cancer metastasis. Recent studies have indicated that the microtubule cytoskeleton and its associated proteins play significant roles in these processes. In this study, we investigated how fidgetin, a microtubule-severing and depolymerizing enzyme, affects EMT and cell migration by depleting it in MDA-MB-231 breast cancer cells. Our data show that depletion of endogenous fidgetin reduces the cell migration rate in both wound-healing and single-cell motility assays. During EMT, transcription factors such as Snail, Slug (Snail2), Twist, and Zeb play pivotal roles by regulating the expression of EMT-related genes. In this study, we found that fidgetin depletion reduces the expression of Slug and Zeb1 in MDA-MB-231 breast cancer cells under both basal and EMT-induced conditions. Consistent with these findings, we observed that fidgetin depletion downregulates N-cadherin and vimentin expression in EMT-induced MDA-MB-231 cells, thereby influencing cell motility. Further investigations revealed that fidgetin also affects microtubule plus-end tracking proteins (+TIPs). Specifically, we detected reduced expression of CLIP-170 in fidgetin-depleted cells. Immunofluorescence analysis showed that EB1 comets occupied a smaller area at microtubule plus ends upon fidgetin depletion. Additionally, the size of focal adhesions was significantly increased, although no changes were observed in the expression levels of focal adhesion kinase (FAK). Our findings indicate that microtubule regulation by fidgetin influences cancer cell motility by altering the expression of EMT-promoting transcription factors and modulating the accumulation of focal adhesion and EB1 proteins. These results suggest that fidgetin could be a promising therapeutic target in cancer.