PCA3 noncoding RNA is involved in the control of prostate-cancer cell survival and modulates androgen receptor signaling
1 Instituto Nacional do Câncer/Programa de Carcinogênese Molecular and Programa de Pós Graduação Stricto Sensu em Oncologia, Rio de Janeiro, Brazil
2 Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
3 Universidade Federal de Goiás, Campus de Catalão, Goiás, Brazil
4 Instituto de Genética e Bioquímica, Laboratório de Nanobiotecnologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
5 Department of Medical Microbiology and Immunology, University of California-Davis, Davis, CA, USA
6 Universidade Federal Fluminense, Rio de Janeiro, Rio de Janeiro, Brazil
7 Departamento Interdisciplinar, Universidade Federal Fluminense-PURO, Rua Recife s/n, CEP: 28890-000, Rio das Ostras, Rio de Janeiro, Brazil
BMC Cancer 2012, 12:507 doi:10.1186/1471-2407-12-507Published: 6 November 2012
PCA3 is a non-coding RNA (ncRNA) that is highly expressed in prostate cancer (PCa) cells, but its functional role is unknown. To investigate its putative function in PCa biology, we used gene expression knockdown by small interference RNA, and also analyzed its involvement in androgen receptor (AR) signaling.
LNCaP and PC3 cells were used as in vitro models for these functional assays, and three different siRNA sequences were specifically designed to target PCA3 exon 4. Transfected cells were analyzed by real-time qRT-PCR and cell growth, viability, and apoptosis assays. Associations between PCA3 and the androgen-receptor (AR) signaling pathway were investigated by treating LNCaP cells with 100 nM dihydrotestosterone (DHT) and with its antagonist (flutamide), and analyzing the expression of some AR-modulated genes (TMPRSS2, NDRG1, GREB1, PSA, AR, FGF8, CdK1, CdK2 and PMEPA1). PCA3 expression levels were investigated in different cell compartments by using differential centrifugation and qRT-PCR.
LNCaP siPCA3-transfected cells significantly inhibited cell growth and viability, and increased the proportion of cells in the sub G0/G1 phase of the cell cycle and the percentage of pyknotic nuclei, compared to those transfected with scramble siRNA (siSCr)-transfected cells. DHT-treated LNCaP cells induced a significant upregulation of PCA3 expression, which was reversed by flutamide. In siPCA3/LNCaP-transfected cells, the expression of AR target genes was downregulated compared to siSCr-transfected cells. The siPCA3 transfection also counteracted DHT stimulatory effects on the AR signaling cascade, significantly downregulating expression of the AR target gene. Analysis of PCA3 expression in different cell compartments provided evidence that the main functional roles of PCA3 occur in the nuclei and microsomal cell fractions.
Our findings suggest that the ncRNA PCA3 is involved in the control of PCa cell survival, in part through modulating AR signaling, which may raise new possibilities of using PCA3 knockdown as an additional therapeutic strategy for PCa control.