MiR-187 Targets the Androgen-Regulated Gene ALDH1A3 in Prostate Cancer

Abstract

miRNAs are predicted to control the activity of approximately 60% of all protein-coding genes participating in the regulation of several cellular processes and diseases, including cancer. Recently, we have demonstrated that miR-187 is significantly downregulated in prostate cancer (PCa) and here we propose a proteomic approach to identify its potential targets. For this purpose, PC-3 cells were transiently transfected with miR-187 precursor and miRNA mimic negative control. Proteins were analyzed by a two-dimensional difference gel electrophoresis (2D-DIGE) and defined as differentially regulated if the observed fold change was ±1.06. Then, MALDI-TOF MS analysis was performed after protein digestion and low abundance proteins were identified by LC–MS/MS. Peptides were identified by searching against the Expasy SWISS PROT database, and target validation was performed both in vitro by western blot and qRT-PCR and in clinical samples by qRT-PCR, immunohistochemistry and ELISA. DIGE analysis showed 9 differentially expressed spots (p<0.05) and 7 showed a down-regulated expression upon miR-187 re-introduction. Among these targets we identified aldehyde dehydrogenase 1A3 (ALDH1A3). ALDH1A3 expression was significantly downregulated in PC3, LNCaP and DU-145 cells after miR-187 re-introduction. Supporting these data, the expression of ALDH1A3 was found significantly (p<0.0001) up-regulated in PCa samples and inversely correlated (p<0.0001) with miR-187 expression, its expression being directly associated with Gleason score (p = 0.05). The expression of ALDH1A3 was measured in urine samples to evaluate the predictive capability of this biomarker for the presence of PCa and, at a signification level of 10%, PSA and also ALDH1A3 were significantly associated with a positive biopsy of PCa. In conclusion, our data illustrate for the first time the role of ALDH1A3 as a miR-187 target in PCa and provide insights in the utility of using this protein as a new biomarker for PCa.

A Prominent Couple

“…The first route is characterized by strong upregulation of the TGF-β receptor ALK1, which can be activated by various BMPs, in addition to TGF-β1 and TGF-β3 [41,42]. Inhibition of ALK1 in our model led to reduced phosphorylation of p38, downregulation of the EMT-markers VIM, MMP1, CDH2, and SNAI2, as well as reduced expression of ID1 and ID2, for which induction by ALK1 signaling is known [43].…”

“…TOP2B) and subsequent recombination suggesting a non-random chromosomal rearrangement in PCa [40,42,43]. In response to genotoxic stress, AR also recruits activation-induced cytidine deaminase (AID) and the LINE-1 encoded endonuclease ORF2 that promote genomic rearrangements [42].…”

“…TOP2B) and subsequent recombination suggesting a non-random chromosomal rearrangement in PCa [40,42,43]. In response to genotoxic stress, AR also recruits activation-induced cytidine deaminase (AID) and the LINE-1 encoded endonuclease ORF2 that promote genomic rearrangements [42]. Exposure of androgen-sensitive fusion-negative LNCaP cells to DHT and irradiation, etoposide or doxorubicin, led to the induction of TMPRSS2:ERG and TMPRSS2:ETV1 gene fusions that corresponded to the identified gene fusion variants in PCa tissue [42].…”

“…For example, JMJD1C, a histone demethylase also known as KDM3C, is involved in maintaining low H3K9me2 levels that are associated with activated target gene expression. JMJD1C has been described as coactivator for several transcription factors including AR [41,42]. A general interaction between Jmj-containing KDM proteins and ERG has been reported to lead to activation of the YAP1 proliferation pathway [43].…”

“…Genes showing >|1.3| fold change compared to control were considered as significantly differentially regulated and used for further analysis using the Ingenuity Pathway analysis (IPA) tool (Supplementary Table S4 Table S4.5) and RNA-seq data in NEPC [2] revealed consistent differential expression, including the genes STEAP1, ALDH1A3, HEPACAM2, and E2F2. For example, ALDH1A3, an AR-regulated gene [40][41][42], and STEAP1, suggested as a marker of prostate adenocarcinoma [43,44], were higher expressed in prostate adenocarcinoma samples compared to NEPC tissue [2] and were upregulated upon INSM1 knockdown.…”