title: Regulation of Axl receptor tyrosine kinase expression by miR-34a and miR-199a/b in solid cancer.
abstract: Axl is a receptor that induces proliferation, migration and invasion in cancer. In this study, we show that specific microRNAs (miRNAs) target the 3'-UTR of Axl. Luciferase-reporter assays with wild-type and deleted miR-34 and miR-199a/b seed sequences of Axl 3'-UTR confirmed the specificity of targeting. An inverse correlation between Axl protein and miR-34a expression in a panel of non-small cell lung cancer (NSCLC), colorectal cancer (CRC) and breast cancer (BRC) cell lines was observed, while miR-199a/b expression was completely suppressed. Pre-miR transfection inhibited in vitro migration and invasion and, in vivo, reduced the number of distant lung- or liver-metastases in a chorion-allantoic-membrane (CAM) assay. Moreover, methylation-specific PCR on bisulfite-converted DNA obtained from the cell lines showed that the miR-34a promoter methylation status was inversely correlated with its expression, and that miR-199a/b promoter regions were methylated in all cells tested. In a panel of NSCLC tissues (n=44), miR-34a and miR-199a/b were found to be downregulated and significantly co-expressed. A lower expression of all three miRs was significantly associated with squamous histotypes, and, in a preliminary series, NSCLC patients with miR-34a upregulation showed a positive association towards a longer survival. These results indicate that Axl receptor expression can be regulated by miR-34a and miR-199a/b, which are suppressed by promoter methylation in solid cancer cells.
authors.affiliation: Department of Experimental Surgery and Molecular Oncology of Solid Tumors, University of Heidelberg, and German Cancer Research Center (DKFZ), Germany.
authors.forename: G
authors.initials: G
authors.lastname: Mudduluru
authors.forename: P
authors.initials: P
authors.lastname: Ceppi
authors.forename: R
authors.initials: R
authors.lastname: Kumarswamy
authors.forename: G V
authors.initials: GV
authors.lastname: Scagliotti
authors.forename: M
authors.initials: M
authors.lastname: Papotti
authors.forename: H
authors.initials: H
authors.lastname: Allgayer
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D019175:DNA Methylation; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness / Q000235:genetics; D009362:Neoplasm Metastasis / Q000235:genetics; D009369:Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D020413:3' Untranslated Regions; C549214:MIRN19A microRNA, human; C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D000094963:Axl Receptor Tyrosine Kinase; C000722289:AXL protein, human