Background: There is evidence that patchouli alcohol (PA) has cytotoxic effects on human cancer cell lines, including inhibiting cell growth, migration, and invasion. However, the exact molecular mechanism of PA in human castration-resistant prostate cancer (CRPC) cells remains unclear. Methods: DU145 and PC-3 cells were treated with different concentrations of PA for 48 h. Cell counting kit-8 (CCK-8), colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) staining were used to detect cell proliferation. Scratch tests and transwell assays were used to detect cell migration and invasion. TdTmediated dUTP nick-end labeling (TUNEL) staining and flow cytometry were performed to examine apoptosis and mitochondrial membrane potential. The expression of the apoptosis-and migration-related proteins and the phosphorylation of the nuclear factor kappa -B (NF-κB) cells were detected by Western blot. A chromatin immunoprecipitation (ChIP) analysis was conducted to examine NF-κB p65 binding to the myeloid cell leukemia-1 (Mcl-1) promoter. A xenograft model of nude mice was established to verify the anticancer effects of PA in vivo. Results: PA inhibited the proliferation, migration, and invasion, and induced the apoptosis of the DU145 and PC-3 cells in a concentration-dependent manner, and was accompanied by mitochondrial membrane potential depolarization, the upregulation of cleaved caspase-3, cleaved poly ADP-ribose polymerase (PARP) and Bcl-2-associated X protein (Bax), and the downregulation of B-cell lymphoma-2 (Bcl-2), Ki67, and Mcl-1. In relation to the mechanism, PA significantly downregulated the phosphorylation of inhibitor of NF-κB α (IκBα) and p65 and the expression of matrix metalloprotein (MMP)-2, MMP-7, MMP-9, and vascular endothelial growth factor (VEGF). PA prevented p65 binding to the Mcl-1 promoter by inactivating NF-κB p65, downregulated the transcription of Mcl-1, and the silencing of p65 increased the sensitivity of the CRPC cells to PA-induced apoptosis. The overexpression of Mcl-1 significantly reversed the PA-induced apoptosis of the CRPC cells. Additionally, consistent with our in-vitro study, PA inhibited tumor growth in the mouse xenograft model. Conclusions:We found that PA inhibits the growth, migration, and invasion of CRPC cells in vitro and in vivo by inducing an apoptosis mechanism and inhibiting NF-κB activity. Our findings may provide therapeutic targets for this malignant tumor.

Background: G protein-coupled bile acid receptor 1 (GPBAR1) is a G protein-coupled receptor for bile acids, which is widely expressed in many human tissues. Patchouli alcohol (PA) has been shown to have an anti-cancer effect, including in prostate cancer (PCa). This study sought to confirm the regulatory mechanism of GPBAR1 in the anti-cancer activity of PA in PCa. Methods:The SwissTargetPrediction website (Pro >0) was used to predict the target of PA. The UALCAN and The Cancer Genome Atlas-Prostate cohort was used to examine the differentially expressed genes and PCa recurrence. A gene set enrichment analysis (GSEA) was conducted to analyze the relationship between the expression of GPBAR1 and PCa proliferation, migration, and invasion. Cell proliferation, migration, and invasion were assessed by colony formation, 5-Ethynyl-2'-deoxyuridine staining, cell scratch assays, and Transwell invasion assays, respectively. A xenograft animal model was established to assess the effect of PA on tumor growth in vivo. GPBAR1 protein and apoptosis related protein expression was measured by western blot.Results: GPBAR1 was a PA target predicted by the SwissTargetPrediction website. PA inhibited the expression of GPBAR1 in PCa cells in a time-and dose-dependent manner. The abnormal expression of GPBAR1 was related to cell proliferation, migration, and invasion. Additionally, GPBAR1 overexpression promoted the cell proliferation, migration, and invasion, and inhibited the apoptosis of PCa cells. GPBAR1 silencing inhibited the cell proliferation, migration, and invasion, and promoted the apoptosis of PCa cells.High expressions of GPBAR1 suppressed tumor growth in tumor-bearing mice. Further, GPBAR1 promoted the activation of nuclear factor kappa B (NF-κB) signaling, and PA regulated the malignant phenotypes of PCa cells via the NF-κB signaling pathway mediated by GPBAR1.Conclusions: GPBAR1 is a promising drug target of PA, and was shown to regulate the proliferation, apoptosis, migration, and invasion of PCa cells through GPBAR1/NF-κB inhibition.