MiR-301a regulates E-cadherin expression and is predictive of prostate cancer recurrence

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression post-transcriptionally. Dysregulation of miRNA has been implicated in the development and progression of prostate cancer. Through next generation miRNA sequencing, we recently identified a panel of five miRNAs associated with prostate cancer recurrence and metastasis. Of the five miRNAs, miR-301a had the strongest association with prostate cancer recurrence. Overexpression of miR-301a in prostate cancer cells, PC3, and LNCaP resulted in increased growth both in vitro and in xenografted tumors. We therefore sought to examine its role in prostate carcinogenesis in greater detail.

We examined the effect of miR-301a expression on biochemical recurrence and metastasis among 585 men treated with radical prostatectomy for prostate cancer. We examined the mechanism of growth deregulation by miR-301a in prostate cancer cells using analysis of the miRome of prostate cancer cell lines, quantitative PCR, and Western blotting.

High levels of miR-301a (above the median) were associated with an increased risk of biochemical recurrence (adjusted hazard ratio [aHR] 1.42, 95% confidence interval (CI) 1.06-1.90, P = 0.002) but not of metastasis (aHR 0.84, 95%CI 0.41-1.70, P = 0.6) after adjustment for known prognostic factors. RNA transcriptome sequencing analysis of miR-301a overexpressing prostate cancer cell lines identified the tumor suppressor p63 as a potential direct miR-301a target. Transcriptome sequencing, qPCR and Western blotting showed that miR-301a induced epithelial-mesenchymal transition (EMT) in prostate cancer cells through a pathway initiated by p63 inhibition. Luciferase assay verified p63 as a direct target of miR-301a. Loss of p63 resulted in miR-205 downregulation, releasing Zeb1 and Zeb2 from inhibition, culminating in Zeb1/Zeb2 suppression of E-cadherin. This pathway of growth alteration mediated by miR-301a upregulation was shown to be valid in prostate cancer cell lines and patient-derived tumors.

These data indicate that miR-301a functions as an oncogene in prostate cancer by directly targeting the p63 tumor suppressor leading to loss of E-cadherin and EMT. Hence, miR-301a may serve as a novel biomarker in prostate cancer as well as a therapeutic target for prostate cancer management. Prostate 76:869-884, 2016. © 2016 Wiley Periodicals, Inc.