title: Integrative analysis of differential miRNA and functional study of miR-21 by seed-targeting inhibition in multiple myeloma cells in response to berberine.
abstract: BACKGROUND
  Berberine is a natural alkaloid derived from a traditional Chinese herbal medicine. It is known to modulate microRNA (miRNA) levels, although the mechanism for this action is unknown. Here, we previously demonstrate that the expression of 87 miRNAs is differentially affected by berberine in multiple myeloma cells. Among 49 miRNAs that are down-regulated, nine act as oncomirs, including miR-21. Integrative analysis showed that 28 of the down-regulated miRNAs participate in tumor protein p53 (TP53) signaling and other cancer pathways. miR-21 is involved in all these pathways, and is one of the most important oncomirs to be affected by berberine in multiple myeloma cells.
  
  
  RESULTS
  We confirmed that berberine down-regulated miRNA-21 expression and significantly up-regulated the expression of programmed cell death 4 (PDCD4), a predicted miR-21 target. Luciferase reporter assays confirmed that PDCD4 was directly regulated by miR-21. Bioinformatic analysis revealed that the miR-21 promoter can be targeted by signal transducer and activator of transcription 3 (STAT3). Down-regulation of interleukin 6 (IL6) by berberine might lead to inhibition of miR-21 transcription through STAT3 down-regulation in multiple myeloma. Furthermore, both berberine and seed-targeting anti-miR-21 oligonucleotide induced apoptosis, G2-phase cell cycle arrest and colony inhibition in multiple myeloma cell lines. Depletion of PDCD4 by short interfering RNA could rescue berberine-induced cytotoxicity in multiple myeloma cells.
  
  
  CONCLUSIONS
  Our results suggest that berberine suppresses multiple myeloma cell growth, at least in part, by down-regulating miR-21 levels possibly through IL6/STAT3. This led to increased PDCD4 expression, which is likely to result in suppression of the p53 signaling pathway. These findings may also provide new mechanistic insight into the anti-cancer effects of certain compounds in traditional Chinese herbal medicines.
authors.forename: Xiaochuang
authors.initials: X
authors.lastname: Luo
authors.forename: Jingyi
authors.initials: J
authors.lastname: Gu
authors.forename: Rongxuan
authors.initials: R
authors.lastname: Zhu
authors.forename: Maoxiao
authors.initials: M
authors.lastname: Feng
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Zhu
authors.forename: Yumin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical College of Jinan University, Guangzhou 510632, China. efeijia@163.com.
authors.forename: Jia
authors.initials: J
authors.lastname: Fei
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D001599:Berberine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019295:Computational Biology; D015536:Down-Regulation / Q000187:drug effects; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D020868:Gene Silencing; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism / Q000494:pharmacology; D035683:MicroRNAs / Q000235:genetics*; D009101:Multiple Myeloma / Q000235:genetics / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D015850:Interleukin-6; C531950:MIRN21 microRNA, mouse; D035683:MicroRNAs; C114487:PDCD4 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D050796:STAT3 Transcription Factor; D001599:Berberine