Synthesis of potent human DHRS11 inhibitors and their efficacy against androgen-dependent proliferation and sensitivity to AKT inhibitor Capivasertib of triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer lacking estrogen receptor (ER), progesterone receptor (PR), and HER2 expression. Among its heterogeneous subtypes, luminal androgen receptor-positive (LAR) TNBC is driven by androgen signaling and presents limited treatment options. We previously identified dehydrogenase/reductase SDR family member 11 (DHRS11) as a novel enzyme involved in androgen biosynthesis, and demonstrated that Kobochromone A (KC-A), a polyphenol isolated from Carex kobomugi, inhibited androgen-driven proliferation in LAR TNBC cells via DHRS11 inhibition and AR downregulation. In this study, we synthesized 23 structural derivatives of KC-A and identified WH23 as the most potent DHRS11 inhibitor (IC₅₀ = 37 nM). Molecular docking and MM-PBSA analysis revealed that the 2'-hydroxy group of WH23 forms a hydrogen bond with His210 of DHRS11, which was validated by site-directed mutagenesis. WH23 suppressed AR mRNA and protein expression, reduced 11-ketodihydrotestosterone (11KDHT)-induced c-Myc expression, and inhibited proliferation of MDA-MB-453 cells. Additionally, WH23 inhibited PI3K/AKT signaling, reducing phosphorylation of PDK1, AKT, mTOR, and ERK. Capivasertib (Cap), a clinically approved pan-AKT inhibitor, induced DHRS11 expression in MDA-MB-453 cells. Although Cap and WH23 did not show synergistic cytotoxicity in parental cells, Cap-resistant (Cap-R) cells, which exhibited elevated DHRS11 and c-Myc expression, showed significant sensitivity to the combination. In Cap-R cells, the combination of Cap and WH23 significantly induced apoptosis, demonstrating a synergistic anticancer effect. These findings establish WH23 as a dual-acting compound targeting both androgen biosynthesis and AR signaling, with potential to overcome AKT inhibitor resistance in LAR TNBC.