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Background
Despite latest advances in prostate cancer (PCa) therapy, PCa remains the third-leading cause of cancer-related death in European men. Dysregulation of microRNAs (miRNAs), small non-coding RNA molecules with gene expression regulatory function, has been reported in all types of epithelial and haematological cancers. In particular, miR-221-5p alterations have been reported in PCa.
Methods
miRNA expression data was retrieved from a comprehensive publicly available dataset of 218 PCa patients (GSE21036) and miR-221-5p expression levels were analysed. The functional role of miR-221-5p was characterised in androgen- dependent and androgen- independent PCa cell line models (C4–2 and PC-3M-Pro4 cells) by miR-221-5p overexpression and knock-down experiments. The metastatic potential of highly aggressive PC-3M-Pro4 cells overexpressing miR-221-5p was determined by studying extravasation in a zebrafish model. Finally, the effect of miR-221-5p overexpression on the growth of PC-3M-Pro4luc2 cells in vivo was studied by orthotopic implantation in male Balb/cByJ nude mice and assessment of tumor growth.
Results
Analysis of microRNA expression dataset for human primary and metastatic PCa samples and control normal adjacent benign prostate revealed miR-221-5p to be significantly downregulated in PCa compared to normal prostate tissue and in metastasis compared to primary PCa. Our in vitro data suggest that miR-221-5p overexpression reduced PCa cell proliferation and colony formation. Furthermore, miR-221-5p overexpression dramatically reduced migration of PCa cells, which was associated with differential expression of selected EMT markers. The functional changes of miR-221-5p overexpression were reversible by the loss of miR-221-5p levels, indicating that the tumor suppressive effects were specific to miR-221-5p. Additionally, miR-221-5p overexpression significantly reduced PC-3M-Pro4 cell extravasation and metastasis formation in a zebrafish model and decreased tumor burden in an orthotopic mouse model of PCa.
Conclusions
Together these data strongly support a tumor suppressive role of miR-221-5p in the context of PCa and its potential as therapeutic target.
Background: Treatment of patients with stage pT1 urothelial bladder cancer (UBC) continues to be a challenge due to its unpredictable clinical course. Reliable molecular markers that help to determine appropriate individual treatment are still lacking. Loss of aquaporin (AQP) 3 protein expression has previously been shown in muscle-invasive UBC. The aim of the present study was to investigate the prognostic value of AQP3 protein expression with regard to the prognosis of stage pT1 UBC.
Method: AQP 3 protein expression was investigated by immunohistochemistry in specimens of 87 stage T1 UBC patients, who were diagnosed by transurethral resection of the bladder (TURB) and subsequent second resection at a high-volume urological centre between 2002 and 2009. Patients underwent adjuvant instillation therapy with Bacillus Calmette-Guerin (BCG). Loss of AQP3 protein expression was defined as complete absence of the protein within the whole tumour. Expression status was correlated retrospectively with clinicopathological and follow-up data (median: 31 months). Multivariate Cox regression analysis was used to assess the value of AQP3 tumour expression with regard to recurrence-free (RFS), progression-free (PFS) and cancer-specific survival (CSS). RFS, PFS and CSS were calculated by Kaplan-Meier analysis and Log rank test.
Results: 59% of patients were shown to exhibit AQP3-positive tumours, whereas 41% of tumours did not express the marker. Loss of AQP3 protein expression was associated with a statistically significantly worse PFS (20% vs. 72%, p=0.020). This finding was confirmed by multivariate Cox regression analysis (HR 7.58, CI 1.29 - 44.68; p=0.025).
Conclusions: Loss of AQP3 protein expression in pT1 UBC appears to play a key role in disease progression and is associated with worse PFS. Considering its potential prognostic value, assessment of AQP3 protein expression could be used to help stratify the behavior of patients with pT1 UBC.