title: Repression of c-Kit by p53 is mediated by miR-34 and is associated with reduced chemoresistance, migration and stemness.
abstract: The c-Kit receptor tyrosine kinase is commonly over-expressed in different types of cancer. p53 activation is known to result in the down-regulation of c-Kit. However, the underlying mechanism has remained unknown. Here, we show that the p53-induced miR-34 microRNA family mediates repression of c-Kit by p53 via a conserved seed-matching sequence in the c-Kit 3'-UTR. Ectopic miR-34a resulted in a decrease in Erk signaling and transformation, which was dependent on the down-regulation of c-Kit expression. Furthermore, ectopic expression of c-Kit conferred resistance of colorectal cancer (CRC) cells to treatment with 5-fluorouracil (5-FU), whereas ectopic miR-34a sensitized the cells to 5-FU. After stimulation with c-Kit ligand/stem cell factor (SCF) Colo320 CRC cells displayed increased migration/invasion, whereas ectopic miR-34a inhibited SCF-induced migration/invasion. Activation of a conditional c-Kit allele induced several stemness markers in DLD-1 CRC cells. In primary CRC samples elevated c-Kit expression also showed a positive correlation with markers of stemness, such as Lgr5, CD44, OLFM4, BMI-1 and β-catenin. On the contrary, activation of a conditional miR-34a allele in DLD-1 cells diminished the expression of c-Kit and several stemness markers (CD44, Lgr5 and BMI-1) and suppressed sphere formation. MiR-34a also suppressed enhanced sphere-formation after exposure to SCF. Taken together, our data establish c-Kit as a new direct target of miR-34 and demonstrate that this regulation interferes with several c-Kit-mediated effects on cancer cells. Therefore, this regulation may be potentially relevant for future diagnostic and therapeutic approaches.
authors.affiliation: Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-University München, D-80337 Munich, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Siemens
authors.forename: Rene
authors.initials: R
authors.lastname: Jackstadt
authors.forename: Markus
authors.initials: M
authors.lastname: Kaller
authors.forename: Heiko
authors.initials: H
authors.lastname: Hermeking
mesh_terms: D020413:3' Untranslated Regions; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001483:Base Sequence; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D000903:Antibiotics, Antineoplastic; C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; D019009:Proto-Oncogene Proteins c-kit