A systematic review of mechanisms of PTEN gene down-regulation mediated by miRNA in prostate cancer.

Background: The Phosphatase and Tensin Homolog gene (PTEN) is pivotal in regulating diverse cellular processes, including growth, differentiation, proliferation, and cell survival, mainly by modulating the PI3K/AKT/mTOR pathway. Alterations in the expression of the PTEN gene have been associated with epigenetic mechanisms, particularly the regulation by small non-coding RNAs, such as miRNAs. Modifications in the expression levels of miRNAs that control PTEN have been shown to lead to its underexpression. This underexpression, in turn, impacts the PI3K/AKT/mTOR pathway, thereby influencing crucial mechanisms like proliferation and apoptosis, playing an important role in the initiation and progression of prostate cancer (PCa). Thus, we aimed to systematically reviewed available information concerning the regulation of PTEN mediated by miRNA in PCa. Methods: Electronic databases were searched to identify studies assessing PTEN regulation via PCa miRNAs, the search included combination of the words microRNAs, PTEN and prostatic neoplasms. The quality assessment of the articles included was carried out using an adapted version of SYRCLE and CASP tool. Results: We included 39 articles that measured the relative gene expression of miRNAs in PCa and their relationship with PTEN regulation. A total of 42 miRNAs were reported involved in the development and progression of PCa via PTEN dysregulation (34 miRNAs up-regulated and eight miRNAs down-regulated). Sixteen miRNAs were shown as the principal regulators for genetic interactions leading to carcinogenesis, being the miR-21 the most reported in PCa associated with PTEN down-regulation. We showed the silencing of PTEN could be promoted by a loop between miR-200b and DNMT1 or by direct targeting of PTEN by microRNAs, leading to the constitutive activation of PI3K/AKT/mTOR and interactions with intermediary genes support apoptosis inhibition, proliferation, invasion, and metastasis in PCa. Conclusion: According to our review, dysregulation of PTEN mediated mainly by miR-21, -20a, -20b, -93, -106a, and -106b up-regulation has a central role in PCa development and could be potential biomarkers for diagnosis, prognostic, and therapeutic targets.