PDLIM2 suppresses the progression of hepatocellular carcinoma via enhancing lipid peroxidation through promoting the ubiquitin-mediated proteasomal degradation of ARL14EP

Abstract Our previous studies have established that PDZ and LIM domain 2 (PDLIM2) played an inhibitory role in the progression of hepatocellular carcinoma (HCC). However, the underlying regulatory mechanisms remain incompletely understood. In this study, we identified ADP-ribosylation factor-like 14 effector protein (ARL14EP) as a potential ubiquitination substrate of PDLIM2 through combined analysis of ubiquitination modification omics and proteomics. PDLIM2 promoted K48-linked polyubiquitination at lysine 257 of ARL14EP in a LIM domain-dependent manner, thereby accelerating its proteasomal degradation and contributing to the suppression of HCC progression. Transcriptomic analyses further revealed that ARL14EP modulated the expression of Cytochrome P450 1A1 (CYP1A1). At the phenotypic level, ARL14EP attenuated lipid peroxidation in HCC cells, resulting in intracellular ferroptosis resistance and lipid accumulation—a process associated with its ubiquitination status. Notably, under conditions of abnormal expression in the PDLIM2-ARL14EP axis, CYP1A1 protein levels were dynamically regulated by the lipid peroxidation status. Meanwhile, we also showed that PDLIM2 enhanced the ubiquitination of ARL14EP via its LIM domain, promoting lipid peroxidation. Collectively, these findings indicate that PDLIM2 exerts its tumor-suppressive function by facilitating LIM domain-dependent K48-linked polyubiquitination and degradation of ARL14EP at K257, enhancing lipid peroxidation, and ultimately inhibiting HCC development.