title: SP1 mediates the link between methylation of the tumour suppressor miR-149 and outcome in colorectal cancer.
abstract: Although recent studies indicate that DNA methylation contributes to the down-regulation of microRNAs (miRNAs) in colorectal cancer (CRC), this field remains largely unexplored. To identify methylation-silenced miRNAs and clarify their role in CRC, we performed a microarray analysis and screened for miRNAs that were induced in CRC cells by 5-aza-2'-deoxycytidine treatment or by the knockdown of DNA methyltransferases. The DNA methylation status of the candidate miRNA was analysed by bisulphite sequencing PCR and methylation-specific PCR. We found that miRNA-149 (miR-149) was epigenetically silenced in CRC and down-regulation of miR-149 was associated with hypermethylation of the neighbouring CpG island (CGI). Quantitative RT-PCR analysis demonstrated that the miR-149 level was markedly reduced in 51.6% of the CRC tissues compared with matched non-cancerous tissues. In addition, low expression of miR-149 was associated with a greater depth of invasion (p = 0.012), lower 5-year survival rate (p = 0.025), and was found to be an independent prognostic factor for overall survival (p = 0.016) in a multivariate analysis. Moreover, transfection of miR-149 inhibited cell growth and invasion of CRC cells in vitro. We also identified mRNA for Specificity Protein 1 (SP1, Sp1), a potential oncogenic protein, as a target of miR-149. Our data suggest that, as a methylation-sensitive miRNA, miR-149 may play an important role as a tumour suppressor in CRC, which has prognostic and therapeutic implications.
authors: Department of Surgery, Shanghai Tenth People's Hospital Affiliated to Tongji University, Shanghai, China.
authors: Feng
authors: F
authors: Wang
authors: Yan-Lei
authors: YL
authors: Ma
authors: Peng
authors: P
authors: Zhang
authors: Tong-Yi
authors: TY
authors: Shen
authors: Chen-Zhang
authors: CZ
authors: Shi
authors: Yong-Zhi
authors: YZ
authors: Yang
authors: Mary-Pat
authors: MP
authors: Moyer
authors: Hui-Zhen
authors: HZ
authors: Zhang
authors: Hong-Qi
authors: HQ
authors: Chen
authors: Yong
authors: Y
authors: Liang
authors: Huan-Long
authors: HL
authors: Qin
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D049109:Cell Proliferation; D016009:Chi-Square Distribution; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D018899:CpG Islands / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000077209:Decitabine; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; C551557:MIRN149 microRNA, human; D035683:MicroRNAs; D016329:Sp1 Transcription Factor; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine