MicroRNA alteration and putative target genes in high‐grade prostatic intraepithelial neoplasia and prostate cancer: STAT3 and ZEB1 are upregulated during prostate carcinogenesis

BACKGROUND We aimed to identify alteration of cancer‐related miRNAs in HGPIN and PCa, and to investigate the clinical implications of HGPIN as a precancerous lesion of PCa. METHODS Clinicopathologic analysis based on the status of HGPIN was performed in 388 patients who received radical prostatectomy between January 2005 and December 2008 in Severance Hospital. Among them, 10 paired HGPIN and PCa were prepared to perform miRNA microarray and quantitative real‐time PCR. Fifty‐two prostatectomy specimens were used to further validation of protein expression that was assessed by immunohistochemical staining (IHC) in matched non‐neoplastic prostatic tissue (NPT), HGPIN, and PCa. Functional analysis was performed using a prostate normal cell line (RWPE‐1) and two prostate cancer cell lines (LNCaP, PC‐3) for comparison of expression of miR‐155 and STAT3 mRNA before and after treatment of miR‐155 mimetics/antagomir into each cell line. RESULTS Patients with HGPIN had significantly less lymphovascular invasion, less lymph node metastasis, lower tumor volume, lower Gleason score, lower incidence of death, and longer overall survival compared to patients without HGPIN. MiR‐155, miR‐210, miR‐153, and miR‐200c were downregulated in HGPIN and PCa in common, compared to NPT. As putative target mRNAs, mRNA expression level of STAT3 , ZEB1 , and BACH1 was increased in PCa and HGPIN compared to NPT. mRNA expression level of ephrin‐A3 was increased in PCa compared to NPT, and FGFRL1 was decreased in PCa compared to HGPIN and NPT. Protein expression assessed by IHC showed correlated results in STAT3, ZEB1, and ephrin‐A3. Moreover, STAT3 and ZEB1 increased in a stepwise manner, from NPT to PCa. Treatment of miR‐155 antagomir increased STAT3 mRNA expression in RWPE‐1 cells, whereas treatment of miR‐155 mimetics into PC‐3 cells significantly decreased STAT3 expression. CONCLUSIONS STAT3 and ZEB1 could be the key molecules altered at the early stages of carcinogenesis, especially in HGPIN. Prostate 76:937–947, 2016 . © 2016 Wiley Periodicals, Inc.