WISP1 inhibition of YAP phosphorylation drives breast cancer growth and chemoresistance via TEAD4 activation.

Wnt1-inducible signaling pathway protein 1 (WISP1) promotes breast cancer. The Hippo signaling pathway demonstrates a potential connection with WISP1, necessitating an exploration of their interaction. This study hypothesized that WISP1 boosts breast cancer by modulating the Hippo signaling pathway. The Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases were used to analyze WISP1 expression and Hippo signaling in breast cancer patients. WISP1, yes-associated protein (YAP), and domain family member 4 (TEAD4) were overexpressed or silenced in breast cancer cells. Epithelial-mesenchymal transition (EMT), and chemoresistance of breast cancer cells were evaluated. Immunofluorescence, PCR, immunoprecipitation, and western blot were used to detect the expression of WISP1 and key Hippo signaling factors and their interactions. Enrichment analysis indicated activation of WISP1 and Hippo signaling pathway and correlated with a worse prognosis in breast cancer. WISP1 overexpression facilitated EMT and chemotherapy resistance in breast cancer. Importantly, overexpression of WISP1 promoted YAP's nuclear translocation. TEAD4 expression in YAP precipitates from nuclear of WISP1-overexpressing MCF-7 cells increased. The promoting effect of WISP1 on breast cancer was counteracted by silencing YAP or TEAD4. Moreover, in WISP1 small interfering RNA-transfected MCF-7 cells, p-YAP expression increased, while interaction between YAP and TEAD4 decreased. WISP1 silencing led to ubiquitin increase and TEAD reduction in the p-YAP precipitates. In conclusion, WISP1 promotes YAP nuclear translocation and binding with TEAD4 by inhibiting YAP phosphorylation, reducing ubiquitin recruitment, and participating in transcriptional regulation in breast cancer.