title: Epigenetic silencing of microRNA-373 plays an important role in regulating cell proliferation in colon cancer.
abstract: microRNAs (miRNA) are non-coding RNAs that negatively control gene expression by cleaving or inhibiting the translation of target gene mRNAs. We used a microarray-based transcriptomic analysis to identify miRNA expression levels that changed in response to epigenetic factors. Specifically, we searched for increased expression of miRNAs prepared from colon cancer cell line DLD-1 after a 96-h treatment with 5 µM of 5-aza-2'-deoxycytidine (DAC). Among those identified, transient transfection of miRNA hsa-miR-373 resulted in cytostasis. In addition, bisulfate sequence analysis of the promoter regions of these miRNAs showed aberrant methylation in the cancer cells. In clinical colon samples, hsa-miR-373 was down-regulated in colon cancers (29/40, 72.5%) relative to control samples, whereas the purported oncogene RAB22A (a target gene of hsa-miR-373) was up-regulated (24/40, 60%). Using methylation-specific PCR, we also observed aberrant methylation of hsa-miR-373 in colon cancers (35/40, 87.5%) relative to controls (8/40, 20%). Based on these results, we conclude that expression of hsa-miR-373 is down-regulated by aberrant methylation in colon cancer and that this miRNA may function by regulating expression of the oncogene RAB22A.
authors.affiliation: Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Makoto
authors.initials: M
authors.lastname: Arai
authors.forename: Shuang
authors.initials: S
authors.lastname: Wu
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kanda
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyauchi
authors.forename: Fumio
authors.initials: F
authors.lastname: Imazeki
authors.forename: Hisahiro
authors.initials: H
authors.lastname: Matsubara
authors.forename: Osamu
authors.initials: O
authors.lastname: Yokosuka
mesh_terms: D048708:Cell Growth Processes / Q000235:genetics; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D019175:DNA Methylation; D057890:Epigenomics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D019073:HT29 Cells; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D008875:Middle Aged; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000235:genetics; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: C527114:MIRN373 microRNA, human; D035683:MicroRNAs; C484191:RAB22A protein, human; D034741:RNA, Small Interfering; D020691:rab GTP-Binding Proteins