GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE339nnn/GSE339459/primaryOK200TranscriptomicsHomo sapiensExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE339459GEOGSEfalse5β-Dihydrotestosterone and mutant androgen receptor vulnerability in prostate cancerBACKGROUND Bipolar androgen therapy (BAT) exploits the paradoxical vulnerability of castration-resistant prostate cancer (CRPC) to supraphysiologic androgen, but current BAT uses testosterone (T), which broadly activates wild-type androgen receptor (AR) in normal androgen-responsive tissues and can cause systemic androgenic effects. 5β-Dihydrotestosterone (5β-DHT), a naturally occurring T metabolite, has been considered androgenically inactive because of weak wild-type AR activity. Here, we examined whether 5β-DHT and related 5β-reduced metabolites activate mutant AR signaling and reproduce BAT-like growth suppression. METHODS Six 5β-reduced T metabolites were evaluated in C4-2 and LNCaP prostate cancer cells under androgen-depleted and BAT-like conditions. AR dependence and mutant-specific activity were assessed using enzalutamide, AR-null PC-3 cells, and PC-3 cells expressing AR-W742C or AR-H875Y. Cell proliferation, AR-responsive reporter activity, RT-qPCR, RNA sequencing with gene set enrichment analysis, immunoblotting, and senescence-associated β-galactosidase staining were used to characterize ligand responses. RESULTS At nanomolar concentrations, 5β-DHT and 3β-etiocholanediol (3β-ecdiol) induced AR target genes and promoted AR-dependent C4-2 and LNCaP growth, although less potently than T. RNA sequencing showed that both metabolites activated the T-regulated AR transcriptional program with smaller differentially expressed gene footprints. At high concentrations, 5β-DHT, but not the weaker agonist 3β-ecdiol or progesterone-class steroids, suppressed C4-2 and LNCaP proliferation. High-dose 5β-DHT also activated AR and suppressed growth in PC-3 cells expressing AR-W742C or AR-H875Y, whereas AR-null PC-3 cells were unaffected. High-dose 5β-DHT enriched androgen-response and senescence programs, suppressed G2M, E2F, and MYC-associated pathways, increased p21, p27, and p57, reduced RB phosphorylation and SKP2, and induced senescence-associated β-galactosidase activity.2026/08/08GSE339459GSM9895982GSM9895981GSM9895980GSM9895989GSM9895988GSM9895987GSM9895986GSM9895985GSM9895984GSM9895983GSM9895993GSM9896004GSM9896003GSM9895992GSM9896002GSM9895991GSM9895990GSM9896001GSM9896000GSM9895999GSM9895998GSM9896009GSM9896008GSM9895997GSM9896007GSM9895996GSM9895995GSM9896006GSM9896005GSM989599424676339459Homo sapiens