Panoply™ Human YAP1 Over-expressing Stable Cell Line

Yes-associated protein 1 (YAP1) is a core component of the Hippo signaling pathway and plays a crucial role in tumor metastasis, yet the precise mechanisms involved remain incompletely understood. Invadopodia are actin-rich cellular protrusions containing various proteases; extensive research has demonstrated that they facilitate cell invasion by degrading the extracellular matrix. This study reveals that YAP1 induces invadopodia formation in breast cancer cells and promotes tumor metastasis. Furthermore, the researchers identified the guanine nucleotide exchange factor TIAM1 as a target of the YAP1-TEAD4 complex. The results show that YAP1 promotes the binding of TEAD4 to the TIAM1 enhancer region, thereby activating TIAM1 expression, enhancing RAC1 activity, and inducing invadopodia formation. These findings elucidate the function of the Hippo signaling pathway in regulating invadopodia and offer potential molecular targets for preventing breast cancer metastasis.

Here, the researchers investigated whether YAP1 is both necessary and sufficient for the formation of invadopodia in breast cancer cells. MCF7 and MDA-MB-231 cells were selected for subsequent studies because they exhibit low and high metastatic potential and invadopodia-forming capabilities, respectively. Gain-of-function and loss-of-function experiments were conducted by performing transient knockdown and stable overexpression of YAP1 in MDA-MB-231 and MCF7 cells, respectively. Western blotting was used to verify the protein levels of YAP1 and its downstream targets (CTGF and CYR61) (Figures 1C, D). Results from Transwell migration, invasion, and wound-healing assays demonstrated that YAP1 regulates the migration and invasion of breast cancer cells in vitro. Immunofluorescence assays showed that YAP1 overexpression induced invadopodia formation and gelatin degradation in MCF7 cells (Figure 1E), whereas knockdown of endogenous YAP1 significantly inhibited invadopodia formation and gelatin degradation in MDA-MB-231 cells (Figure 1F). Furthermore, in 3D tumor spheroid invasion assays, YAP1 overexpression induced the formation of invadopodia-like structures at the periphery of MCF7 spheroids; conversely, YAP1 knockdown significantly inhibited the growth and invasive capacity of MDA-MB-231 cells in a 3D culture environment. Finally, the researchers stably overexpressed exogenous YAP1 in MCF-10A cells and confirmed that YAP1 could induce the formation of invadopodia-like structures in non-tumorigenic mammary epithelial cells. Taken together, these data indicate that YAP1 is both necessary and sufficient for invadopodia formation in breast cancer cell lines.

Figure 1. YAP1 is necessary and sufficient for invadopodia formation in breast cancer cell lines. (Shen J, et al., 2022)