Project description:Bone morphogenetic protein 4 (BMP4) is a remarkably powerful inhibitor of breast cancer cell proliferation, but is also able to induce breast cancer cell migration in certain cellular contexts. Previous data demonstrate that BMP4 controls the transcription of a variety of protein coding genes, but not much is known about microRNAs (miRNA) regulated by BMP4. In this study, miRNA expression patterns following BMP4 treatment were determined in one mammary epithelial and seven breast cancer cell lines using microarrays. The analysis identified 20 to 128 differentially expressed miRNAs in individual cell lines with emphasis on upregulation over downregulation. Four miRNAs (miR-16-5p, miR-106b-5p, miR-23a-3p and miR-23b-3p) were commonly induced in a subset of breast cancer cells upon BMP4 treatment and inhibition of their expression resulted in an increase in BT-474 cell number, indicating that they possess tumor suppressive properties. Yet no major change was detected when the cells were simultaneously treated with BMP4, and thus these miRNAs do not act as the main mediators of BMP4-induced growth reduction. MiR-16-5p and miR-106b-5p were elevated in MDA-MB-231 cells that respond to BMP4 with increased migration. Their inhibition, in combination with BMP4 treatment, resulted in enhanced MDA-MB-231 cell migration, suggesting that miR-16-5p and miR-106b-5p are engaged in BMP4-induced motility. Taken together, we have shown for the first time that in breast cancer cells BMP4 induces variable miRNA expression patterns.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:Bone Morphogenetic Protein Receptor Antagonists Inhibit Growth and Survival of Lung Cancer Cells Expressing Stem Cell Markers Oct4 or Nestin