title: MicroRNA-199a targets CD44 to suppress the tumorigenicity and multidrug resistance of ovarian cancer-initiating cells.
abstract: In ovarian cancer, CD44(+) /CD117(+)  stem cells, also known as cancer-initiating cells (CICs), are highly proliferative, have a low degree of differentiation, and are resistant to chemotherapeutics. Therefore, the CD44(+) /CD117(+)  subpopulation is thought to be an important target for novel therapeutic strategies. In this study, we investigated the role of microRNA-199a (miR-199a) in ovarian cancer stem cells. Luciferase reporter gene assays confirmed that miR-199a targets CD44 via an miR-199a-binding site in the 3'-UTR. CD44(+) /CD117(+)  ovarian CICs were enriched from human primary ovarian tumor tissues and confirmed by flow cytometric sorting. miR-199a was cloned and transfected into ovarian CICs. CD44 mRNA and protein expression was significantly decreased in miR-199a-transfected ovarian CICs as compared with miR-199a mutant-transfected and untransfected cells. Cell cycle analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide proliferation assays, the colony formation assay and the transwell migration assay indicated that miR-199a significantly affected cell cycle regulation and suppressed the proliferation and invasive capacity of ovarian CICs in vitro. miR-199a significantly increased the chemosensitivity of ovarian CICs to cisplatin, pacitaxel, and adriamycin, and reduced mRNA expression of the multidrug resistance gene ABCG2 as compared with miR-199a mutant-transfected and untransfected cells. The expression of stemness markers was also significantly reduced in miR-199a-transfected CICs as compared with miR-199a mutant-transfected and untransfected ovarian cells. Furthermore, xenograft experiments confirmed that miR-199a suppressed the growth of xenograft tumors formed by ovarian CICs in vivo. Thus, expression of endogenous mature miR-199a may prevent tumorigenesis in human ovarian cancer by regulating expression of its target gene CD44.
authors.affiliation: International Peace Maternity and Child Health Hospital, Shanghai Jiaotong University, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Cheng
authors.forename: Te
authors.initials: T
authors.lastname: Liu
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wan
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Gao
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics; D002277:Carcinoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D002465:Cell Movement; D049109:Cell Proliferation; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases / Q000235:genetics; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
chemical_list: D020413:3' Untranslated Regions; C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D018960:Hyaluronan Receptors; D035683:MicroRNAs; D009363:Neoplasm Proteins; C531408:mirn199 microRNA, human; D008156:Luciferases