BACKGROUND: Enzalutamide, a second-generation androgen receptor (AR) pathway inhibitor, is widely used in the treatment of castration-resistant prostate cancer. However, after a period of enzalutamide treatment, patients inevitably develop drug resistance. In this study, we characterized leucine-rich repeated G-protein-coupled receptor 5 (LGR5) and explored its potential therapeutic value in prostate cancer. METHODS: A total of 142 pairs of tumor and adjacent formalin-fixed paraf-fin-embedded tissue samples from patients with prostate cancer were collected from the Pathology Department at Sun Yat-sen Memorial Hos-pital. LGR5 was screened by sequencing data of enzalutamide-resistant cell lines combined with sequencing data of lesions with different Gleason scores from the same patients. The biological function of LGR5 and its effect on enzalutamide resistance were investigated in vitro and in vivo . Glutathione-S-transferase (GST) pull-down, coimmunoprecipitation, Western blotting, and immunofluorescence assays were used to explore the specific binding mechanism of LGR5 and related pathway changes. RESULTS: LGR5 was significantly upregulated in prostate cancer and negatively correlated with poor patient prognosis. Overexpression of LGR5 promoted the malignant progression of prostate cancer and reduced sensitivity to enzalutamide in vitro and in vivo . LGR5 promoted the phosphorylation of glycogen synthase kinase-3β (GSK-3β) by binding heat shock protein 90,000 alpha B1 (HSP90AB1) and mediated the activation of the Wingless/integrated (WNT)/β-catenin signaling pathway. The increased β-catenin in the cytoplasm entered the nucleus and bound to the nuclear AR, promoting the transcription level of AR, which led to the enhanced tolerance of prostate cancer to enzalutamide. Reducing HSP90AB1 binding to LGR5 significantly enhanced sensitivity to enzalutamide. CONCLUSIONS LGR5 directly binds to HSP90AB1 and mediates GSK-3β phosphorylation, promoting AR expression by regulating the WNT/β-catenin signaling pathway, thereby conferring resistance to enzalutamide treatment in prostate cancer.
Male ; Humans ; Phenylthiohydantoin/pharmacology* ; Benzamides ; Receptors, G-Protein-Coupled/genetics* ; Nitriles ; Cell Line, Tumor ; HSP90 Heat-Shock Proteins/metabolism* ; Drug Resistance, Neoplasm/genetics* ; Prostatic Neoplasms/drug therapy* ; beta Catenin/metabolism* ; Receptors, Androgen/genetics* ; Animals ; Mice ; Wnt Signaling Pathway/physiology*

Androgen receptor (AR) is a ligand-activated transcription factor that plays a pivotal role in the development and progression of many severe diseases such as prostate cancer, muscle atrophy, and osteoporosis. Binding of ligands to AR triggers the conformational changes in AR that may affect the recruitment of coactivators and downstream response of AR signaling pathway. Therefore, AR ligands have great potential to treat these diseases. In this study, we searched for novel AR ligands by performing a docking-based virtual screening (VS) on the basis of the crystal structure of the AR ligand binding domain (LBD) in complex with its agonist. A total of 58 structurally diverse compounds were selected and subjected to LBD affinity assay, with five of them (HBP1-3, HBP1-17, HBP1-38, HBP1-51, and HBP1-58) exhibiting strong binding to AR-LBD. The IC values of HBP1-51 and HBP1-58 are 3.96 µM and 4.92 µM, respectively, which are even lower than that of enzalutamide (Enz, IC = 13.87 µM), a marketed second-generation AR antagonist. Further bioactivity assays suggest that HBP1-51 is an AR agonist, whereas HBP1-58 is an AR antagonist. In addition, molecular dynamics (MD) simulations and principal components analysis (PCA) were carried out to reveal the binding principle of the newly-identified AR ligands toward AR. Our modeling results indicate that the conformational changes of helix 12 induced by the bindings of antagonist and agonist are visibly different. In summary, the current study provides a highly efficient way to discover novel AR ligands, which could serve as the starting point for development of new therapeutics for AR-related diseases.
Androgen Receptor Antagonists ; pharmacology ; Androgens ; metabolism ; pharmacology ; Biological Assay ; Cell Line, Tumor ; Drug Discovery ; methods ; Humans ; Ligands ; Male ; Molecular Docking Simulation ; Molecular Dynamics Simulation ; Phenylthiohydantoin ; analogs & derivatives ; pharmacology ; Principal Component Analysis ; Prostatic Neoplasms ; drug therapy ; Protein Binding ; physiology ; Protein Conformation ; drug effects ; Receptors, Androgen ; metabolism

Objective: To establish enzalutamide-resistant human prostate cancer cell lines and screen out the lncRNA and mRNA expression profiles associated with enzalutamide resistance. METHODS: Human prostate cancer cell lines LNCAP and C4-2B were cultured with 10 μmol/L enzalutamide for 6 months in vitro for the establishment of enzalutamide-resistant subclones LNCAP-ENZA and C4-2B-ENZA. The IC50 value and enzalutamide resistance index of each cell line were examined by MTT assay, the expressions of enzalutamide-related genes FL-AR, AR-V7 and HnRNPA1 were determined by Western blot, and the lncRNA and mRNA differential expressions of C4-2B and C4-2B-ENZA were detected by high-throughout lncRNA microarray. RESULTS: Compared with LNCAP and C4-2B, the IC50 values of enzalutamide-resistant subclones LNCAP-ENZA (60.83 μmol/L) and C4-2B-ENZA (88.32 μmol/L) were increased significantly (P < 0.05) and the enzalutamide-resistance indexes of the LNCAP-ENZA and C4-2B-ENZA cells were 4.94 and 4.67, respectively. The expressions of AR-V7 and HnRNPA1 were markedly up-regulated in the LNCAP-ENZA and C4-2B-ENZA cells as compared with those in the LNCAP and C4-2B cells, but that of FL-AR showed no significant change. A total of 1 440 lncRNAs and 1 236 mRNAs were identified as differentially expressed in the C4-2B-ENZA cells. CONCLUSIONS Enzalutamide -resistant human prostate cancer cell subclones LNCAP-ENZA and C4-2B-ENZA were successfully established and enzalutamide resistance-associated lncRNA and mRNA were identified, which may provide some molecular evidence for the management of enzalutamide-resistant human prostate cancer.
Cell Line, Tumor ; drug effects ; Drug Resistance, Neoplasm ; Humans ; Male ; Phenylthiohydantoin ; analogs & derivatives ; pharmacology ; Prostatic Neoplasms ; drug therapy ; genetics ; pathology ; RNA, Long Noncoding ; metabolism ; RNA, Messenger ; metabolism ; RNA, Neoplasm ; metabolism ; Receptors, Androgen