Data from m⁶A Modification Promotes EMT and Metastasis of Castration-Resistant Prostate Cancer by Upregulating NFIB

Abstract The widespread use of androgen receptor (AR) signaling inhibitors has led to an increased incidence of AR-negative castration-resistant prostate cancer (CRPC), limiting effective treatment and patient survival. A more comprehensive understanding of the molecular mechanisms supporting AR-negative CRPC could reveal therapeutic vulnerabilities to improve treatment. This study showed that the transcription factor nuclear factor I/B (NFIB) was upregulated in patient with AR-negative CRPC tumors and cell lines and was positively associated with an epithelial-to-mesenchymal transition (EMT) phenotype. Loss of NFIB inhibited EMT and reduced migration of CRPC cells. NFIB directly bound to gene promoters and regulated the transcription of EMT-related factors E-cadherin (CDH1) and vimentin (VIM), independent of other typical EMT-related transcriptional factors. In vivo data further supported the positive role of NFIB in the metastasis of AR-negative CRPC cells. Moreover, N⁶-methyladenosine (m⁶A) modification induced NFIB upregulation in AR-negative CRPC. Mechanistically, the m⁶A levels of mRNA, including NFIB and its E3 ubiquitin ligase TRIM8, were increased in AR-negative CRPC cells. Elevated m⁶A methylation of NFIB mRNA recruited YTHDF2 to increase mRNA stability and protein expression. Inversely, the m⁶A modification of TRIM8 mRNA, induced by ALKBH5 downregulation, decreased its translation and expression, which further promoted NFIB protein stability. Overall, this study reveals that upregulation of NFIB, mediated by m⁶A modification, triggers EMT and metastasis in AR-negative CRPC. Targeting the m⁶A/NFIB axis is a potential prevention and treatment strategy for AR-negative CRPC metastasis. Significance: NFIB upregulation mediated by increased m⁶A levels in AR-negative castration-resistant prostate cancer regulates transcription of EMT-related factors to promote metastasis, providing a potential therapeutic target to improve prostate cancer treatment.