Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines

Abstract

The MDM2-p53 pathway plays a pivotal role in regulating cell cycle and apoptosis, with its dysfunction contributing to approximately 50% of human malignancies. MDM2, an E3 ubiquitin ligase, targets the tumour suppressor p53 for degradation, thereby promoting uncontrolled cell growth in cancers. Inhibiting the MDM2-p53 interaction represents a promising therapeutic strategy for reactivating p53’s tumour-suppressive functions. This study explored the potential of ibutamoren (IBU) as a novel inhibitor of MDM2. In silico analyses utilizing molecular modelling revealed that IBU has a low IC₅₀ for MDM2 inhibition and favourably binds to the p53-binding pocket of MDM2. In vitro experiments demonstrated that IBU treatment reduced the viability of immortalized cancer cell lines with a functional MDM2-p53 pathway but not in cell lines where this pathway harboured damaging mutations. This trend was further supported by RT-qPCR analysis, which showed differential expression of two p53 target genes upon IBU treatment in cell lines with wild MDM2-p53 pathways but not in those harbouring damaging mutations. These findings provide preliminary evidence supporting IBU's anticancer activity, plausibly through the MDM2-p53 pathway, and suggest that further studies are warranted to explore its mechanism of action and potential development as a lead compound in oncology research.