MicroRNAs (
miRNAs) are short (19-24 nt), low molecular weight RNAs that play important roles in the regulation of target genes associated with cell proliferation, differentiation, and development, by binding to the 3'-untranslated region of the target mRNAs. In this study, we examined the expression of miRNA-126 (miR-126) and miR-149 in
prostate cancer, and investigated the molecular mechanisms by which they affect
syndecan-1 in
prostate cancer. Functional analysis of miR-126 and miR-149 was conducted in the
prostate cancer cell lines, PC3, Du145, and LNCaP. The expression levels of SOX2, NANOG, Oct4, miR-126 and miR-149 were evaluated by quantitative RT-PCR. After silencing
syndecan-1, miR-126, and/or miR-149 in the PC3 cells, cell proliferation, senescence, and p21 induction were assessed using the MTS assay, senescence-associated β-
galactosidase (SA-β-Gal) assay, and immunocytochemistry, respectively. Compared to the Du145 and LNCaP cells, PC3 cells exhibited higher expression of
syndecan-1. When
syndecan-1 was silenced, the PC3 cells showed reduced expression of miR-126 and miR-149 most effectively. Suppression of miR-126 and/or miR-149 significantly inhibited cell growth via p21 induction and subsequently, induced senescence. The
mRNA expression levels of SOX2, NANOG, and Oct4 were significantly increased in response to the silencing of miR-126 and/or miR-149. Our results suggest that miR-126 and miR-149 are associated with the expression of
syndecan-1 in
prostate cancer cells. These
miRNAs promote cell proliferation by suppressing SOX2, NANOG, and Oct4. The regulation of these factors by miR-126 and miR-149 is essential for syndecan-1-mediated development of
androgen-refractory
prostate cancer.