4-Nerolidylcatechol binds to Derlin-1 and modulates endoplasmic reticulum stress markers of androgen-independent prostate cancer cells.

Abstract

Castration-resistant prostate cancer (CRPC) is a lethal disease characterized by androgen receptor-independent activation mechanisms that promote prolonged or unresolved endoplasmic reticulum (ER) stress. Consequently, these cells rely on the endoplasmic reticulum-associated degradation (ERAD) pathway, specifically Derlin-1, to maintain proteostasis under chronic stress, which makes this protein a significant therapeutic target. We previously demonstrated that 4-Nerolidylcatechol (4-NC), the main secondary metabolite of Piper umbellatum (capeba), downregulates the epithelial-mesenchymal transition in androgen-independent prostate cancer cells (PC-3). In this study, we aimed to evaluate the potential of 4-NC to interact with Derlin-1 and modulate redox status and ER stress markers using in silico and in vitro approaches. Docking simulations and 100-ns molecular dynamics predicted that 4-NC binds within the Derlin-1 retrotranslocation channel, establishing polar interactions with Arg85 and Thr88 and hydrophobic contacts with Val142, Met140, Ala152, and Leu155, thereby conferring conformational stability to the complex in silico. In PC-3 cells, 4-NC exhibited concentration-dependent cytotoxicity and antiproliferative selectivity, with IC50 values of 39.2 μM in PC-3 and 86.7 μM in non-neoplastic PNT-2 cells (SRB assay; p < 0.05). Functional assays showed that 4-NC, at sub-cytotoxic concentrations, significantly increased intracellular reactive oxygen species levels, reduced glutathione levels by up to approximately 70%, enhanced lipid peroxidation, and progressively induced mitochondrial depolarization in PC-3 cells (p < 0.05). Consistently, 4-NC induced the expression of transcripts related to UPR/ERAD pathways (ATF4, BiP, EDEM, CHOP) and altered the proteome of treated PC-3 cells, indicating the activation of ER stress responses and a shift toward a pro-apoptotic transcriptional profile at higher concentrations. These findings highlight 4-NC as a promising natural compound for targeting the Derlin-1/ERAD axis, shedding light on mechanisms and promising targets not yet described in CRPC. Although previous reports demonstrated that 4-NC regulates the epithelial-mesenchymal transition in PC-3 cells, the present study identified, for the first time, Derlin-1 as a potential molecular target of 4-NC, highlighting the role of ER stress in CRPC.