PTGES3 proteolysis using the liposomal peptide-PROTAC approach.

Background: Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide, and the lack of effective biomarkers for early detection leads to poor therapeutic outcomes. Prostaglandin E Synthase 3 (PTGES3) is a putative prognostic marker in many solid tumors; however, its expression and biological functions in HCC have not been determined. The proteolysis-targeting chimera (PROTAC) is an established technology for targeted protein degradation. Compared to the small-molecule PROTAC, the peptide PROTAC (p-PROTAC) utilizes peptides bound to target proteins to mediate the ubiquitination and degradation of undruggable proteins. This study aimed to use the PROTAC technology to develop a PTGES3 degrader liposome complex containing a PTGES3-binding peptide and the E3 ubiquitin ligase ligand pomalidomide for regulating cell function and provide a novel pathway for treating HCC.

Results: In this study, we demonstrated that PTGES3 is highly expressed in HCC at the transcriptional and protein levels; furthermore, PTGES3 was identified as a novel drug target that could potentially treat HCC. Hence, we developed PTGES3-PROTACs by adjusting the ligand ratio to optimize the efficacy of degradation agents. The results revealed that PTGES3-PROTAC effectively degraded PTGES3 protein and strongly weakened the HCC malignant phenotype in vitro and in vivo.

Conclusions: Our findings revealed that the highly selective PTGES3 proteolysis is a potential therapeutic strategy for HCC, and PTGES3 degraders PTGES3-PROTACs can be developed as safe and effective drugs for HCC treatment.