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The therapeutic efficacy of metformin in prostate cancer (PCa) appears uncertain based on various clinical trials. Metformin treatment failure may be attributed to the high frequency of transcriptional dysregulation, which leads to drug resistance. However, the underlying mechanism is still unclear. In this study, we found evidences that metformin resistance in PCa cells may be linked to cell cycle reactivation. Super-enhancers (SEs), crucial regulatory elements, have been shown to be associated with drug resistance in various cancers. Our analysis of SEs in metformin-resistant (MetR) PCa cells revealed a correlation with Prostaglandin Reductase 1 (PTGR1) expression, which was identified as significantly increased in a cluster of cells with metformin resistance through single-cell transcriptome sequencing. Our functional experiments showed that PTGR1 overexpression accelerated cell cycle progression by promoting progression from the G0/G1 to the S and G2/M phases, resulting in reduced sensitivity to metformin. Additionally, we identified key transcription factors that significantly increase PTGR1 expression, such as SRF and RUNX3, providing potential new targets to address metformin resistance in PCa. In conclusion, our study sheds new light on the cellular mechanism underlying metformin resistance and the regulation of the SE-TFs-PTGR1 axis, offering potential avenues to enhance metformins therapeutic efficacy in PCa.

Aim: To elucidates the mechanism that disulfiram/copper complex (DSF/Cu) treatment activates chloride channels and induces apoptosis in prostate cancer cells. Methods: Cellular membrane currents were measured by membrane clamp technique; western blot to detect protein expression; flow cytometry to detect apoptosis; immunofluorescence to detect target protein co‐localization, and further validated by a combination of protein‐protein interaction and mock protein molecular docking techniques. Results: DSF/Cu activated chloride channels and induced apoptosis in LNCaP (a type of androgen‐dependent prostate cancer cells) cells. The chloride currents activated by DSF/Cu were significantly reduced after knockdown of CLC3 with siRNA. In addition, DSF/Cu‐activated chloride currents were reduced to background current levels after perfusion with genistein, a highly specific tyrosine kinase inhibitor. Conversely, DSF/Cu failed to activate chloride currents in LNCaP cells after 30 minutes of pre‐incubation with genistein. When genistein was removed, and DSF/Cu was added, the activated currents were small and unstable, and gradually decreased. Immunofluorescence in LNCaP cells also showed co‐localization of the CLC3 protein with tyrosine kinase 2β (PTK2B). Conclusion: DSF/Cu can activate chloride channels and induce apoptosis in LNCaP cells with the involvement of tyrosine kinase. These results provide new insights into the target therapy of prostate cancer. [ABSTRACT FROM AUTHOR]

Aim: To elucidates the mechanism that disulfiram/copper complex (DSF/Cu) treatment activates chloride channels and induces apoptosis in prostate cancer cells., Methods: Cellular membrane currents were measured by membrane clamp technique; western blot to detect protein expression; flow cytometry to detect apoptosis; immunofluorescence to detect target protein co-localization, and further validated by a combination of protein-protein interaction and mock protein molecular docking techniques., Results: DSF/Cu activated chloride channels and induced apoptosis in LNCaP (a type of androgen-dependent prostate cancer cells) cells. The chloride currents activated by DSF/Cu were significantly reduced after knockdown of CLC3 with siRNA. In addition, DSF/Cu-activated chloride currents were reduced to background current levels after perfusion with genistein, a highly specific tyrosine kinase inhibitor. Conversely, DSF/Cu failed to activate chloride currents in LNCaP cells after 30 minutes of pre-incubation with genistein. When genistein was removed, and DSF/Cu was added, the activated currents were small and unstable, and gradually decreased. Immunofluorescence in LNCaP cells also showed co-localization of the CLC3 protein with tyrosine kinase 2β (PTK2B)., Conclusion: DSF/Cu can activate chloride channels and induce apoptosis in LNCaP cells with the involvement of tyrosine kinase. These results provide new insights into the target therapy of prostate cancer., (© 2021 The Authors. Asia-Pacific Journal of Clinical Oncology published by John Wiley & Sons Australia, Ltd.)

Objective: B-cell lymphoma 9 (BCL9) as a co-activator for β-catenin-mediated transcription is highly expressed in tumors. The aim of our study is to investigate the expression of BCL9, and its clinicopathological significance in prostate cancer (PCa)., Methods: Immunohistochemistry was conducted to analyze the expression of BCL9 in 98 PCa samples and 20 benign prostate hyperplasia (BPH) samples. The associations of BCL9 expression with clinicopathological features and prognosis in PCa patients were analyzed with various statistical methods, such as chi-square test, Kaplan-Meier method and log-rank test., Results: The positive rate of BCL9 was 53.1% (52/98) in prostate cancer group, and 25.0% (5/20) in benign group (P=0.022). In addition, BCL9 expression in PCa tissues was significantly associated with Gleason score (P=0.016), and biochemical recurrence (P=0.020). Moreover, Kaplan-Meier survival analysis showed that the higher expression of BCL9 was correlated with shorter biochemical recurrence-free survival (P=0.037). However, BCL9 was not an independent prognostic predictor for biochemical recurrence-free survival in patients with PCa after the multivariate analysis was conducted (Hazard ratio =1.73, P=0.384)., Conclusion: Our study demonstrates the up-regulation of BCL9 is associated with PCa's early diagnosis and malignant degree.