title: MicroRNA 345, a methylation-sensitive microRNA is involved in cell proliferation and invasion in human colorectal cancer.
abstract: Aberrant methylation has been shown to trigger the inactivation of tumor suppressor genes during tumorigenesis. MicroRNAs (miRNAs) have been found deregulated in human colorectal cancer (CRC), and some of them may function as tumor suppressor genes. Here, we investigated CpG island promoter hypermethylation as a potential mechanism underlying miRNA disruption and identifed methylation-sensitive miRNAs that might repress CRC development. We compared differential expression of miRNAs after 5-aza-2'-deoxycitidine (5-aza-dC) treatment using microarrays. DNA methylation status of the candidate miRNA was analyzed. The candidate miRNA was transfected into CRC cells and growth-suppressive mechanisms were explored. Luciferase reporter assay and western blot were used to identify the target genes of the candidate miRNA. The expression of mir-345 was significantly increased after 5-aza-dC treatment. DNA methylation analyses of mir-345 showed high methylation levels in tumor versus normal tissues. Expression of mir-345 was significantly down-regulated in 51.6% of CRC tissues compared with corresponding non-cancerous tissues. Low expression of mir-345 was associated with lymph node metastasis and worse histological type. Increased mir-345 function was sufficient to suppress colon cancer cell proliferation and invasiveness in vitro. Furthermore, we identified BCL2-associated athanogene 3 (BAG3), an anti-apoptosis protein, to be a target of mir-345. These results suggested as a methylation-sensitive miRNA in CRC, mir-345 may play an important role of antineoplastic as a growth inhibitor in the development of CRC.
authors.affiliation: Digestive Department, Shanghai Institute of Digestive Disease, Shanghai Jiaotong University School of Medicine Renji Hospital, 145 Middle Shandong Road, Shanghai, China.
authors.forename: Jie-Ting
authors.initials: JT
authors.lastname: Tang
authors.forename: Ji-Lin
authors.initials: JL
authors.lastname: Wang
authors.forename: Wan
authors.initials: W
authors.lastname: Du
authors.forename: Jie
authors.initials: J
authors.lastname: Hong
authors.forename: Shu-Liang
authors.initials: SL
authors.lastname: Zhao
authors.forename: Ying-Chao
authors.initials: YC
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Xiong
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Chen
authors.forename: Jing-Yuan
authors.initials: JY
authors.lastname: Fang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002465:Cell Movement; D049109:Cell Proliferation; D047369:Chromatin Immunoprecipitation; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D018899:CpG Islands; D019175:DNA Methylation; D017931:DNA Primers; D000077209:Decitabine; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2; D006801:Humans; D007124:Immunoenzyme Techniques; D008156:Luciferases / Q000378:metabolism; D008207:Lymphatic Metastasis; D008297:Male; D035683:MicroRNAs / Q000502:physiology*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D017931:DNA Primers; C561417:MIRN345 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; D000077209:Decitabine; D008156:Luciferases; D001374:Azacitidine