FOXP3 inhibits proliferation and migration by competitively inhibiting YAP1 in nasopharyngeal carcinoma

Hippo signalling is involved in the coordination of extracellular signals that control tissue homeostasis and organ size. Yes-associated protein 1 (YAP1) is regulated primarily by Hippo signalling through coactivation of transcription factors with GATA domains called TEADs. However, small-molecule orthosteric inhibitors of YAP1 are difficult to develop due to its tight binding to TEAD4 via a flat interface. Previous studies have shown that chlorpromazine (CPZ) can inhibit YAP1 expression. MTT, colony formation, wound healing, Transwell migration and Western blot assays were performed to explore how CPZ affects nasopharyngeal carcinoma (NPC) cells through FOXP3. In addition, immunofluorescence and live-cell imaging were used to detect YAP1 intracellular localization after CPZ administration. Through the HDOCK website, we predicted protein binding regions between FOXP3 and TEAD4. Western blot and co-IP experiments were used to verify the relationship between FOXP3 and YAP1. The UCSC Xena database, LinkedOmics database and KM plotter website were used to assess the prognostic value of FOXP3 in head and neck squamous cell carcinoma (HNSCC). Age, sex, pathological tumour-node-metastasis (pTMN) stage, grade, smoking status and FOXP3 expression were included in an overall survival nomogram model. Our findings revealed that FOXP3 has the ability to competitively interacts competitively with TEAD4 to inhibit YAP1 expression. By increasing FOXP3 expression, CPZ induces YAP1 nuclear export and phosphorylation, consequently suppressing NPC cell proliferation and migration. Collectively, our findings indicate that FOXP3 competitively binds TEAD4 to regulate YAP1 localization in the nucleus and cytoplasm to suppress NPC progression. Consequently, FOXP3 may be a prognostic indicator for HNSCC.