The Ubiquitin E3 Ligase FBXO33 Suppresses Stem Cell-Like Properties and Metastasis in Non-Small-Cell Lung Cancer by Promoting Ubiquitination and Degradation of Myc.

BACKGROUND: Non-small cell lung cancer (NSCLC) is a malignant form of lung cancer, and its prognosis could be improved by identifying key therapeutic targets. Thus, this study investigates the potential role of F-box Only Protein 33 (FBXO33) in NSCLC.

METHODS: The expression levels of FBXO33 in NSCLC were determined using University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN) prediction, and its correlation with overall survival (OS) was analyzed via Kaplan-Meier survival analysis. These results were validated through quantitative polymerase chain reaction (qPCR), western blot (WB), and immunofluorescence (IF). We modulated FBXO33 expression by overexpression or knockdown and analyzed its effects on cell growth, proliferation, migration, invasion, and stemness characteristics in NSCLC cell lines. Additionally, the interaction between FBXO33 and Myelocytomatosis (Myc) and its impact on Myc ubiquitination were examined. An in vivo NSCLC xenograft model was used to corroborate the in vivo experimental results.

RESULTS: The study found an inverse correlation between FBXO33 expression in NSCLC and OS. Lower FBXO33 expression enhanced the growth, proliferation, migration, invasion, and stemness characteristics of NSCLC cell lines. FBXO33 interacted with Myc to promote its ubiquitination and subsequent degradation, which suppressed NSCLC development.

CONCLUSION: FBXO33 is expressed at low levels in NSCLC and correlates with lower OS. Overexpression of FBXO33 promotes Myc ubiquitination and degradation and inhibits tumor cell proliferation, migration and stemness characteristics, thereby impeding NSCLC progression.