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.
Subject(s)
Adenosine , Epithelial-Mesenchymal Transition , Gene Expression Regulation, Neoplastic , NFI Transcription Factors , Prostatic Neoplasms, Castration-Resistant , Up-Regulation , Male , Humans , Prostatic Neoplasms, Castration-Resistant/pathology , Prostatic Neoplasms, Castration-Resistant/metabolism , Prostatic Neoplasms, Castration-Resistant/genetics , NFI Transcription Factors/metabolism , NFI Transcription Factors/genetics , Mice , Animals , Adenosine/analogs & derivatives , Adenosine/metabolism , Cell Line, Tumor , Mice, Nude , Receptors, Androgen/metabolism , Receptors, Androgen/genetics , Cell Movement , Neoplasm Metastasis , Mice, Inbred BALB C , Xenograft Model Antitumor Assays , Cell ProliferationABSTRACT
<p><b>OBJECTIVE</b>To investigate the interaction between hydrogen sulfide (H2S)/cystathionine gamma-lyase (CSE) system and nitric oxide (NO)/nitric oxide synthase (NOS) system on cardiac protection in metabolic syndrome (MS) rats.</p><p><b>METHODS</b>Forty one male Sprague-Dawley rats were randomly divided into 6 groups: control group, MS group, H2S donor group, CSE inhibitor group, NOS inhibitor group, and NO donor group. The MS rat model was established by a high-fat diet of 16 weeks. Rats in control and MS groups were subjected to normal saline and the other four groups were respectively subjected to sodium hydrosulfide (NaHS, 56 μmol/kg), D,L-propargylglycine (PPG, 37.5 mg/kg), Nψ-nitro-L-arginine methyl ester (L-NAME, 18 mg/kg), L-Arginine (500 mg/kg) every day. Four weeks later, the obesity indices, blood sugar of oral glucose tolerance test in each time point (0,30,60, and 120 minutes) and blood lipids (cholesterol, triglyceride, high density lipoprotein, low density lipoprotein) were measured. The computer-based electrophysiological recorder system was used to measure the changes of the left ventricular systolic pressure (LVSP), the left ventricular end diastolic pressure (LVEDP), the maximal rate of pressure increase in the contraction phase (+dP/dtmax), and the maximal rate of pressure decrease in the diastole phase (-dP/dtmax). H2S and NO concentration in plasma and myocardium, as well as CSE, constitutive NOS (cNOS), and inducible NOS (iNOS) activities in myocardium were measured with colorimetric method. Reverse transcription-polymerase chain reaction was used to assess the gene expression of CSE and endothelial NOS (eNOS) mRNAs.</p><p><b>RESULTS</b>Compared with control group, the obesity indices, blood sugar at each time point, and blood lipids significantly increased in MS group (P<0.05). H2S and NO concentration in plasma and myocardium, CSE and cNOS activities in myocardium, the expressions of CSE mRNA and eNOS mRNA, and the myocardial function significantly decreased in MS group (P<0.05). Compared with MS group, NO concentration in plasma and myocardium, cNOS and iNOS activities in myocardium, and the expression of eNOS mRNA significantly increased in CSE inhibitor group (P<0.05). However, activities of cNOS and iNOS in myocardium and the expression of eNOS mRNA were significantly decreased in H2S donor group (P<0.01), while the myocardial function significantly increased (P<0.05). H2S concentration in plasma and myocardium, and the expression of CSE mRNA significantly increased in NOS inhibitor group (P<0.05). However, in NO donor group, the CSE activity in myocardium and the expression of CSE mRNA significantly decreased (P<0.05). And the myocardial function was improved significantly (P<0.05).</p><p><b>CONCLUSIONS</b>Both the H2S/CSE and NO/NOS systems appear to have a mutual down-regulation effect on myocardium in MS rats. Meanwhile, exogenous H2S and NO supplement is cardioprotective in rat model of MS.</p>
