title: MiR-20a and miR-20b negatively regulate autophagy by targeting RB1CC1/FIP200 in breast cancer cells.
abstract: OBJECTIVE
  RB1CC1/FIP200 was essential for autophagosome formation. Therefore, RB1CC1/FIP200 cellular levels are critical for the activation of the autophagy pathways. Following the screen of miRNAs affecting RB1CC1/FIP200 level and rapamycin-induced autophagy, we discovered miR-20a and miR-20b could regulate autophagy by targeting RB1CC1/FIP200.
  
  
  METHODS
  Inhibitory effect of miR-20a and 20b on basal and rapamycin-stimulated autophagy was demonstrated using various autophagic tests including GFP-LC3 puncta analysis, LC3II/LC3I gel shift and TEM observation.
  
  
  RESULTS
  We discovered RB1CC1/FIP200 as cellular targets of miR-20a and miR-20b. Upon miR-20a and miR-20b overexpression, both mRNA and protein levels of RB1CC1/FIP200 decreased. miR-20a and miR-20b target sequences present in the 3' UTR of RB1CC1/FIP200 mRNAs and introduction of mutations abolished the miR-20a and miR-20b responsiveness. In MCF7 and MDA-MB-231 breast cancer cells, miR-20a and miR-20b over-expression attenuated basal and rapamycin-induced autophagy; while suppression of miR-20a or miR-20b by specific antagomir showed normal rapamycin-induced autophagic activity.
  
  
  CONCLUSIONS
  To our knowledge, this is the first study showing the significance of miR-20a and miR-20b regulating autophagy by targeting RB1CC1/FIP200.
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China. Electronic address: shufengli@seu.edu.cn.
authors.forename: Shufeng
authors.initials: S
authors.lastname: Li
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Qiang
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Shan
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Minke
authors.initials: M
authors.lastname: Shi
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Gan
authors.affiliation: Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Department of Biochemistry and Molecular Biology, Medical School of Southeast University, Nanjing 210009, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Ma
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China. Electronic address: cbaoj_608@126.com.
authors.forename: Baojun
authors.initials: B
authors.lastname: Chen
mesh_terms: D001343:Autophagy / Q000235:genetics*; D000071183:Autophagy-Related Proteins; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D061986:MCF-7 Cells; D035683:MicroRNAs / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology
chemical_list: D000071183:Autophagy-Related Proteins; C534451:MIRN20a microRNA, human; D035683:MicroRNAs; C407704:RB1CC1 protein, human; D012333:RNA, Messenger; D011505:Protein-Tyrosine Kinases; D020123:Sirolimus
keywords: Autophagy; Breast cancer; RB1CC1/FIP200; miR-20a; miR-20b