Ectopic expression of miR-126*, an intronic product of the vascular endothelial EGF-like 7 gene, regulates prostein translation and invasiveness of prostate cancer LNCaP cells

Abstract

MicroRNAs (miRNAs) are endogenous noncoding RNAs that down-regulate gene expression by promoting cleavage or translational arrest of target mRNAs. While most miRNAs are transcribed from their own dedicated genes, some map to introns of 'host' transcripts, the biological significance of which remains unknown. Here, we show that prostate cells are naturally devoid of EGF-like domain 7 (Egfl7) transcripts and hence also deficient in a miRNA, miR-126*, generated from splicing and processing of its ninth intron. Use of recombinant and synthetic miRNAs or a specific antagomir established a role of miR-126* in silencing prostein in non-endothelial cells. We mapped two miR-126*-binding sites in the 3′UTR of the prostein mRNA required for translational repression. Transfection of synthetic miR-126* into prostate cancer LNCaP cells strongly reduced the translation of prostein. Interestingly, loss of prostein correlated with reduction of LNCaP cell migration and invasion. Thus, the robust expression of prostein protein in the prostate cells results from a combination of transcriptional activation of the prostein gene and absence of intronic miRNA-126* due to the prostate-specific repression of the Egfl7 gene. We conclude that intronic miRNAs from tissue-specific transcripts, or their natural absence, make cardinal contributions to cellular gene expression and phenotype. These findings also open the door to tissue-specific miRNA therapy.

Micro RNA-126 coordinates cell behavior and signaling cascades according to characteristics of breast cancer cells

“…Also, it has been reported that the increase in the prostein protein expression in prostate cells was due to the absence of miR-126* found in Egfl -7 gene (36). In a non-small cell lung cancer (NSCLC) study, a signifi cant reduction in CRK protein which is the functional target of miR-126 was observed while cells were transfected with pre-miR-126 (6).…”

miR-126 Suppresses the Proliferation of Cervical Cancer Cells and Alters Cell Sensitivity to the Chemotherapeutic Drug Bleomycin

“…Some studies have also demonstrated that miR-126 has roles in regulating adhesion molecule expression (Harris et al, 2008), providing additional control of vascular inflammation (Harris et al, 2008), regulating the VEGF/PI3K/AKT signaling pathway (Hu et al, 2010), regulating the translation and invasiveness of vascular endothelial cell sprouting (Musiyenko et al, 2008), and governing the integrity and angiogenesis of the vasculature (Kuhnert et al, 2008;Wang et al, 2008b). Using MTT assays, our research showed that the SR of Siha-miR-126 mimic was significantly reduced compared to that of control cells and that the differences between the 2 cell groups increased over time.…”

Comprehensive analysis of mammalian miRNA* species and their role in myeloid cells

“…Furthermore, we were able to unambiguously annotate the miRNA* strand of miRNAs such as miR-423 and miR-371. Other recent miRNA profiling efforts have found differentially expressed miRNA*s, such as miR-9*, 39 miR-199*, 40,41 miR-126*, 42,43 miR-363*, 44 miR-18*, 45 miR-29c*, 46 and miR-155*, 47 in the pathogenesis of Waldenström macroglobulinemia, lung cancer, and a metastasis model, as well as in developmental processes such as organ adhesion, respectively. In our libraries, hsa-miR-199 showed features of an ␣-duplex, whereas hsa-miR-9 and hsa-miR-363 displayed a more balanced expression (supplemental Table 2).…”