Abstract 2522: MiRNA-652 induces neuroendocrine-like differentiation in LNCaP prostate cancer cells through decreased PP2A function
Authors: Benatar Tania , Amemiya Yutaka , Wallis Christopher J. , Sugar Linda , Sherman Christopher , Nam Robert , Seth Arun K. 
Published: July 2017

Background: MicroRNA (miRNA) dysregulation has been shown to contribute to prostate cancer progression. Recently, we identified a panel of five miRNAs associated with prostate cancer recurrence and metastasis using next generation miRNA sequencing. Here, we examine the clinical implications of dysregulation of miR-652 and its biological mechanism.

Methods: Using a cohort of 585 patients treated with radical prostatectomy, we examined the prognostic significance of miR-652 using the Kaplan Meier method and Cox proportional hazard models. We examined miR-652 expression in prostate cancer cells and created cell lines that overexpressed miR-652 for functional assays. Finally, we examined pathways through which miR-652 may function using prediction algorithms, and confirmed by Western blotting, IHC and luciferase reporter assays.

Results: Patients overexpressing miR-652 had significantly increased rates of biochemical recurrence (p&lt;0.0001). In multivariable models adjusting for known clinical prognostic factors, patients with high miR-652 expression had an increased risk of biochemical recurrence (HR 1.47, 95% CI 1.09-1.98). Overexpression of miR-652 in PC3 and LNCaP cells resulted in increased growth, migration and invasion. Prostate cancer cell xenografts overexpressing miR-652 had increased tumorigenicity and metastases. Using the miRNA target prediction program miRanda, we identified the B” regulatory subunit, PPP2R3A, of the tumor suppressor PP2A as a potential target of miR-652. PC3 and LNCaP cells transfected with miR-652 mimic dowregulated the PR72 isoform of PPP2R3A. Mutation of the miR-652 binding site in the PPP2R3A gene negated this effect. Western blotting demonstrated that mir-652 induced PPR2R3A inhibition induced epithelial-mesenchymal transition (EMT) in PC3 cells. Prolonged miR-652 expression in LNCaP cells induced a neurite-like morphology, suggesting neurodocrine-like differentiation (NED). Western blotting of LNCaP cells after prolonged miR-652 exposure, resulted in increased phospho-AKT and phospho-β-catenin (phosphorylated at Serine 552), reduced AR expression, and upregulation of the NED marker, neuron specific enolase (NSE), consistent with NED. Expression of NED markers, chromogranin A, NSE, and synaptophysin were also observed in a xenografted tumor derived from LNCaP-652 overexpressing cells.

Conclusion: These observations suggest that increased levels of miR-652 found in prostate cancer may contribute to tumor progression by promoting NED, tumor cell survival and cell migration/invasion through decreased PP2A function which may provide an opportunity for novel therapy in prostate cancer.

Citation Format: Tania Benatar, Yutaka Amemiya, Christopher J. Wallis, Linda Sugar, Christopher Sherman, Robert Nam, Arun K. Seth. MiRNA-652 induces neuroendocrine-like differentiation in LNCaP prostate cancer cells through decreased PP2A function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2522. doi:10.1158/1538-7445.AM2017-2522