Etoposide suppresses skin cutaneous melanoma growth by inducing ferroptosis through p53-mediated transcriptional inhibition of TSP50.

Testis-specific protease 50 (TSP50), a tumor-associated antigen with minimal expression in normal tissues, emerges as a promising therapeutic target. In this study, we report its aberrant overexpression and proliferation-promoting role in skin cutaneous melanoma (SKCM). Using a TSP50 promoter-driven luciferase reporter system, we identified etoposide-an FDA-approved topoisomerase II (TOP2) inhibitor-as a potent suppressor of TSP50 transcription. Etoposide can effectively reduces the activity of TSP50 promoter, thereby inhibiting its mRNA and protein expression. Functionally, etoposide markedly inhibits SKCM cells proliferation and triggers ferroptosis, with these effects mediated by TSP50 downregulation. In xenograft models, etoposide treatment significantly attenuated tumor growth with favorable safety profiles. Mechanistically, etoposide stabilizes p53 by weakening the MDM2-p53 interaction while enhancing MDM2-TOP2α binding. CUT&Tag and RT-qPCR revealed that p53 binds to a specific region (-200 to -249 bp) of TSP50 promotor, leading to transcriptional repression. Our findings delineate a novel TOP2α/MDM2/p53/TSP50 axis in SKCM and propose etoposide as a precision therapy for TSP50-overexpressing melanomas.