E3 Ubiquitin Ligase ITCH Enhances P53 Ubiquitination-Dependent Degradation and Drives Osteosarcoma Tumorigenesis.

Osteosarcoma remains a highly aggressive malignant tumor with strong metastatic potential and limited therapeutic options. E3 ubiquitin ligases, particularly the HECT-type family, regulate oncogenic pathways via targeted protein degradation. Among them, Itchy E3 ubiquitin protein ligase (ITCH) has been implicated in poor prognosis in multiple cancers. However, its functional effects and clinical relevance in osteosarcoma pathogenesis remain completely unexplored. Herein, ITCH expression in osteosarcoma tissues was detected using qRT-PCR, Western blot, and IHC. In vitro and in vivo, the function of ITCH was evaluated by soft agar colony formation assay, Transwell assay, CCK8 assay, wound healing assay, immunofluorescence, flow cytometric analysis, and xenograft tumor assay. Downstream targets were further investigated using proteomic analysis, Western blot, and immunoprecipitation. ITCH was aberrantly overexpressed in osteosarcoma tissues, exhibiting a strong negative correlation with patient survival. Mechanistically, ITCH directly bound P53 and mediated its ubiquitination and degradation. ITCH-driven P53 loss enhanced malignant phenotypes, whereas ITCH knockdown restored P53 stability. This study demonstrates that ITCH functions as an oncogene in osteosarcoma by targeting P53 for degradation and suggests ITCH as a promising therapeutic target. IMPLICATIONS: These findings define a molecular mechanism underlying the oncogenic role of ITCH through P53 ubiquitination-dependent degradation.