MicroRNA‐199a targets CD44 to suppress the tumorigenicity and multidrug resistance of ovarian cancer‐initiating cells

• Published in: The FEBS journal 2012-06, Vol.279 (11), p.2047-2059
• Main Authors: Cheng, Weiwei, Liu, Te, Wan, Xiaoping, Gao, Yongtao, Wang, Hui
• Format: Article
• Language: English
• Subjects: 3' Untranslated Regions - genetics; Adult; Animals; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - therapeutic use; ATP Binding Cassette Transporter, Sub-Family G, Member 2; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Biomarkers, Tumor - biosynthesis; Biomarkers, Tumor - genetics; cancer‐initiating/stem cells; Carcinoma - drug therapy; Carcinoma - genetics; Carcinoma - pathology; Cell Cycle; Cell Movement; Cell Proliferation; Cellular biology; Drug resistance; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Gene expression; Genes, Reporter; Humans; Hyaluronan Receptors - genetics; Hyaluronan Receptors - metabolism; Luciferases - genetics; Mice; microRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; Middle Aged; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Neoplastic Stem Cells - metabolism; Neoplastic Stem Cells - pathology; Ovarian cancer; Ovarian Neoplasms - drug therapy; Ovarian Neoplasms - genetics; Ovarian Neoplasms - pathology; Ribonucleic acid; RNA; Stem cells; Tumors; Xenograft Model Antitumor Assays
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2012.08589.x

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. The experiments confirmed that miR‐199a significantly affected cell cycle regulation and suppressed the proliferation and invasive capacity of ovarian CICs, and significantly increased the chemosensitivity of ovarian CICs to chemotherapeutic drugs in vitro. Furthermore, xenograft experiments confirmed that miR‐199a suppressed the growth of xenograft tumors formed by ovarian CICs in vivo. Thus, miR‐199a may prevent tumorigenesis in human ovarian cancer.