title: Strand-specific miR-28-5p and miR-28-3p have distinct effects in colorectal cancer cells.
abstract: OBJECTIVE
  MicroRNAs (miRNAs) can promote or inhibit tumor growth and are therefore being developed as targets for cancer therapies. They are diverse not only in the messenger RNAs (mRNA) they target, but in their production; the same hairpin RNA structure can generate mature products from each strand, termed 5p and 3p, that can bind different mRNAs. We analyzed the expression, functions, and mechanisms of miR-28-5p and miR-28-3p in colorectal cancer (CRC) cells.
  
  
  METHODS
  We measured levels of miR-28-5p and miR-28-3p expression in 108 CRC and 49 normal colorectal samples (47 paired) by reverse transcription, quantitative real-time polymerase chain reaction. The roles of miR-28 in CRC development were studied using cultured HCT116, RKO, and SW480 cells and tumor xenograft analyses in immunodeficient mice; their mRNA targets were also investigated.
  
  
  RESULTS
  miR-28-5p and miR-28-3p were down-regulated in CRC samples compared with normal colon samples. Overexpression of miRNAs in CRC cells had different effects and the miRNAs interacted with different mRNAs: miR-28-5p altered expression of CCND1 and HOXB3, whereas miR-28-3p bound NM23-H1. Overexpression of miR-28-5p reduced CRC cell proliferation, migration, and invasion in vitro, whereas miR-28-3p increased CRC cell migration and invasion in vitro. CRC cells overexpressing miR-28 developed tumors more slowly in mice compared with control cells, but miR-28 promoted tumor metastasis in mice.
  
  
  CONCLUSIONS
  miR-28-5p and miR-28-3p are transcribed from the same RNA hairpin and are down-regulated in CRC cells. Overexpression of each has different effects on CRC cell proliferation and migration. Such information has a direct application for the design of miRNA gene therapy trials.
authors.affiliation: Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Almeida
authors.forename: Milena S
authors.initials: MS
authors.lastname: Nicoloso
authors.forename: Lizhi
authors.initials: L
authors.lastname: Zeng
authors.forename: Cristina
authors.initials: C
authors.lastname: Ivan
authors.forename: Riccardo
authors.initials: R
authors.lastname: Spizzo
authors.forename: Roberta
authors.initials: R
authors.lastname: Gafà
authors.forename: Lianchun
authors.initials: L
authors.lastname: Xiao
authors.forename: Xinna
authors.initials: X
authors.lastname: Zhang
authors.forename: Ivan
authors.initials: I
authors.lastname: Vannini
authors.forename: Francesca
authors.initials: F
authors.lastname: Fanini
authors.forename: Muller
authors.initials: M
authors.lastname: Fabbri
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lanza
authors.forename: Rui M
authors.initials: RM
authors.lastname: Reis
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Zweidler-McKay
authors.forename: George A
authors.initials: GA
authors.lastname: Calin
mesh_terms: D000818:Animals; D017209:Apoptosis; D016022:Case-Control Studies; D002465:Cell Movement; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy; D045325:HCT116 Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D035683:MicroRNAs / Q000378:metabolism*; D054778:NM23 Nucleoside Diphosphate Kinases / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D015375:Receptors, Interleukin-2 / Q000172:deficiency / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
chemical_list: C530104:CCND1 protein, human; D018398:Homeodomain Proteins; C542921:HoxB3 protein, human; C570628:MIRN28 microRNA, human; D035683:MicroRNAs; D054778:NM23 Nucleoside Diphosphate Kinases; D015375:Receptors, Interleukin-2; D019938:Cyclin D1; C517938:NME1 protein, human