Abstract 3166: Molecular target regulated by tumor suppressive <i>microRNA-1</i> and <i>microRNA-133a</i> in prostate cancer
Authors: Miki Fuse, Satoko Kojima, Takeshi Chiyomaru, Hirofumi Yoshino, Hideki Enokida, Masayuki Nakagawa, Nijiro Nohata, Tomohiko Ichikawa, Yukio Naya, Naohiko Seki
Journal: Cancer Research (2012)

Abstract (Background) Prostate cancer (PCa) is the most frequently diagnosed and second leading cause of cancer death among men in developing countries. Hormone-refractory PCa is currently difficult to treat and most clinical trials for advanced PCa have shown limited benefits, with disease progression and metastasis to bone or other sites. Thus, new prognostic markers and effective treatment strategies are urgently needed. Our expression signatures of human cancer including prostate cancer revealed that the expression of microRNA-1 (miR-1) and microRNA-133a (miR-133a) were significantly reduced in cancer cells. In human genome, miR-1 and miR-133a located same chromosomal regions called cluster. In this study, we investigated the functional significance of miR-1 and miR-133a and identified the novel molecular targets regulated by miR-1 and miR-133a commonly in PCa. (Methods) Cell proliferation, invasion and migration assays were performed by restoration of mature miR-1 and/or miR-133a in PCa cell lines (PC3 and DU145). Genome-wide gene expression analysis was performed to identify the molecular targets of miR-1 and miR-133a by microarray methods. A luciferase reporter assay was used to identify the actual binding site between miR-1 and miR-133a and its candidate target genes. Cell proliferation, invasion and migration assays were performed to investigate the targets genes in PCa cell lines. To investigate of expression of candidate target gene, immunohistochemistry was performed by using PCa tissue microarray. (Results) Restoration of miR-1 and/or miR-133a significantly inhibited cell proliferation, migration and invasion in cancer cells. Genome-wide molecular targets search and luciferase reporter assay showed that 6 genes: Transgelin2 (TAGLN2), WD repeat domain 78 (WDR78), chromosome 4 open reading frame 34 (C4orf34), purine nucleoside phosphorylase (PNP), LAG1 homologue, ceramide synthase 2 (LASS2) and syntaxin binding protein (STXBP4) had putative target sites of both miR-1 and miR-133a in their 3′UTR. Among them, PNP mRNA was highly expressed in the PCa clinical specimen compered with non-PCa tisses. The mRNA and protein expression levels of PNP were markedly downregulated in miR-1 and miR-133a -transfected PCa cells. A luciferase reporter assay suggested that miR-1 and miR-133a directly bind to specific sites on 3′UTR of PNP mRNA. Silencing of the target genes inhibited cell proliferation, migration, and invasion in PCa cells. Immunohistochemistry showed that PNP expression level was significantly higher in PCa than normal prostate tissues. (Conclusions) miR-1 and miR-133a function as tumor suppressor in PCa. PNP was directly regulated by tumor suppressive miR-1 and miR-133a commonly. PNP may function as oncogenes in PCa. Tumor suppressive miR-1 and miR-133a mediates novel molecular targets provide new insights of molecular mechanisms of PCa oncogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3166. doi:1538-7445.AM2012-3166