title: miR-340 inhibits tumor cell proliferation and induces apoptosis by targeting multiple negative regulators of p27 in non-small cell lung cancer.
abstract: MicroRNAs (miRNAs) control cell cycle progression by targeting the transcripts encoding for cyclins, CDKs and CDK inhibitors, such as p27(KIP1) (p27). p27 expression is controlled by multiple transcriptional and posttranscriptional mechanisms, including translational inhibition by miR-221/222 and posttranslational regulation by the SCF(SKP2) complex. The oncosuppressor activity of miR-340 has been recently characterized in breast, colorectal and osteosarcoma tumor cells. However, the mechanisms underlying miR-340-induced cell growth arrest have not been elucidated. Here, we describe miR-340 as a novel tumor suppressor in non-small cell lung cancer (NSCLC). Starting from the observation that the growth-inhibitory and proapoptotic effects of miR-340 correlate with the accumulation of p27 in lung adenocarcinoma and glioblastoma cells, we have analyzed the functional relationship between miR-340 and p27 expression. miR-340 targets three key negative regulators of p27. The miR-340-mediated inhibition of both Pumilio family RNA-binding proteins (PUM1 and PUM2), required for the miR-221/222 interaction with the p27 3'-UTR, antagonizes the miRNA-dependent downregulation of p27. At the same time, miR-340 induces the stabilization of p27 by targeting SKP2, the key posttranslational regulator of p27. Therefore, miR-340 controls p27 at both translational and posttranslational levels. Accordingly, the inhibition of either PUM1 or SKP2 partially recapitulates the miR-340 effect on cell proliferation and apoptosis. In addition to the effect on tumor cell proliferation, miR-340 also inhibits intercellular adhesion and motility in lung cancer cells. These changes correlate with the miR-340-mediated inhibition of previously validated (MET and ROCK1) and potentially novel (RHOA and CDH1) miR-340 target transcripts. Finally, we show that in a small cohort of NSCLC patients (n=23), representative of all four stages of lung cancer, miR-340 expression inversely correlates with clinical staging, thus suggesting that miR-340 downregulation contributes to the disease progression.
authors.affiliation: CNR Institute of Genetics and Biophysics, Naples, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Fernandez
authors.affiliation: CNR Institute of Genetics and Biophysics, Naples, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Risolino
authors.affiliation: CNR Institute of Genetics and Biophysics, Naples, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Mandia
authors.affiliation: CNR Institute of Genetics and Biophysics, Naples, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Talotta
authors.affiliation: Institute of Clinical Medicine, Pathology and Forensic Medicine, School of Medicine, Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland.
authors.forename: Y
authors.initials: Y
authors.lastname: Soini
authors.affiliation: IRCCS SDN, Naples, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Incoronato
authors.affiliation: Department of Cellular and Molecular Biology and Pathology, ''Federico II'' University of Naples, Naples, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Condorelli
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Banfi
authors.affiliation: 1] CNR Institute of Genetics and Biophysics, Naples, Italy [2] IRCCS SDN, Naples, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Verde
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D017209:Apoptosis / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology*; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: C570046:MIRN340 microRNA, human; D035683:MicroRNAs; C471242:PUM1 protein, human; C471243:PUM2 protein, human; D016601:RNA-Binding Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27