β-hydroxybutyrate inhibits malignant phenotypes of prostate cancer cells through β-hydroxybutyrylation of indoleacetamide-N-methyltransferase.

BACKGROUND: Prostate cancer (PCa) is one of the most prevalent cancers in men and is associated with high mortality and disability rates. β-hydroxybutyrate (BHB), a ketone body, has received increasing attention for its role in cancer. However, its role in PCa remains unclear. This study aimed to explore the mechanism and feasibility of BHB as a treatment alternative for PCa.

METHODS: Colony formation assay, flow cytometry, western blot assay, and transwell assays were performed to determine the effect of BHB on the proliferation and metastasis of PCa cells. Tumor sphere formation and aldehyde dehydrogenase assays were used to identify the impact of BHB or indoleacetamide-N-methyltransferase (INMT) on the stemness of PCa cells. N6-methyladenosine (m6A)-meRIP real-time reverse transcription polymerase chain reaction and dual luciferase assays were conducted to confirm INMT upregulation via the METTL3-m6A pathway. Co-IP assay was used to detect the epigenetic modification of INMT by BHB-mediated β-hydroxybutyrylation (kbhb) and screen enzymes that regulate INMT kbhb. Mouse xenograft experiments demonstrated the antitumor effects of BHB in vivo.

RESULTS: BHB can inhibit the proliferation, migration, and invasion of PCa cells by suppressing their stemness. Mechanistically, INMT, whose expression is upregulated by the METTL3-m6A pathway, was demonstrated to be an oncogenic gene that promotes the stem-like characteristics of PCa cells. BHB can suppress the malignant phenotypes of PCa by kbhb of INMT, which in turn inhibits INMT expression.

CONCLUSIONS: Our findings indicate a role of BHB in PCa metabolic therapy, thereby suggesting an epigenetic therapeutic strategy to target INMT in aggressive PCa.

TRIAL REGISTRATION: Not applicable.