TFAP2C-mediated transcriptional activation of STEAP3 promotes lung squamous cell carcinoma progression by regulating the β-catenin pathway.

Six-transmembrane epithelial antigen of prostate 3 (STEAP3) is associated with the progression of several human malignancies. However, its role in lung squamous cell carcinoma (LUSC) remains unclear. We measured STEAP3 expression in LUSC cell lines and tissues. LUSC cells with stable STEAP3 overexpression and knockdown were obtained through G418 selection. Multiple assays were used to evaluate the malignant phenotypes of LUSC cells and the activation of the β-catenin signaling. The potential transcriptional regulatory factors of STEAP3 were predicted using the JASPAR database, and the correlation between transcription factor AP-2 gamma (TFAP2C) and STEAP3 was analyzed through the GEPIA database. The study evaluated the regulatory relationship between a potential transcription factor and STEAP3 through ChIP and luciferase reporter assays. Additionally, rescue assays were utilized to ascertain whether TFAP2C serves as the upstream regulatory factor of STEAP3, contributing to LUSC progression. Finally, tumor growth and metastasis were evaluated in vivo. STEAP3 expression was notably higher in LUSC, and its overexpression was linked to a poor prognosis. Moreover, STEAP3 overexpression activated the β-catenin pathway, thereby accelerating cell proliferation and metastasis. Conversely, STEAP3 knockdown had an anti-tumor effect in LUSC. Additionally, TFAP2C bound directly to the STEAP3 promoter and positively regulate its expression in LUSC. The anti-tumor effects of TFAP2C knockdown were partially reversed by STEAP3 overexpression. The study indicates that the TFAP2C/STEAP3 axis may be a therapeutic target for LUSC treatment. This enhances our understanding of lung carcinogenesis.