title: Pancreatic cancers epigenetically silence SIP1 and hypomethylate and overexpress miR-200a/200b in association with elevated circulating miR-200a and miR-200b levels.
abstract: Aberrant DNA methylation and microRNA expression play important roles in the pathogenesis of pancreatic cancer. While interrogating differentially methylated CpG islands in pancreatic cancer, we identified two members of miR-200 family, miR-200a and miR-200b, that were hypomethylated and overexpressed in pancreatic cancer. We also identified prevalent hypermethylation and silencing of one of their downstream targets, SIP1 (ZFHX1B, ZEB2), whose protein product suppresses E-cadherin expression and contributes to epithelial mesenchymal transition. In a panel of 23 pancreatic cell lines, we observed a reciprocal correlation between miR-200, SIP1, and E-cadherin expression, with pancreatic cancer-associated fibroblasts showing the opposite expression pattern to most pancreatic cancers. In Panc-1 cells, which express SIP1, have low E-cadherin expression, and do not express miR-200a or miR-200b, treatment with miR-200a and miR-200b downregulated SIP1 mRNA and increased E-cadherin expression. However, most pancreatic cancers express miR-200a and miR-200b, but this expression does not affect SIP1 expression, as the SIP1 promoter is silenced by hypermethylation and in these cancers E-cadherin is generally expressed. Both miR-200a and miR-200b were significantly elevated in the sera of pancreatic cancer and chronic pancreatitis patients compared with healthy controls (P < 0.0001), yielding receiver operating characteristic curve areas of 0.861 and 0.85, respectively. In conclusion, most pancreatic cancers display hypomethylation and overexpression of miR-200a and miR-200b, silencing of SIP1 by promoter methylation, and retention of E-cadherin expression. The elevated serum levels of miR-200a and miR-200b in most patients with pancreatic cancer could have diagnostic utility.
authors.affiliation: Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, Johns Hopkins University, Baltimore, Maryland 21231, USA.
authors.forename: Ang
authors.initials: A
authors.lastname: Li
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Omura
authors.forename: Seung-Mo
authors.initials: SM
authors.lastname: Hong
authors.forename: Audrey
authors.initials: A
authors.lastname: Vincent
authors.forename: Kimberly
authors.initials: K
authors.lastname: Walter
authors.forename: Margaret
authors.initials: M
authors.lastname: Griffith
authors.forename: Michael
authors.initials: M
authors.lastname: Borges
authors.forename: Michael
authors.initials: M
authors.lastname: Goggins
mesh_terms: D000328:Adult; D015820:Cadherins / Q000096:biosynthesis / Q000235:genetics; D021441:Carcinoma, Pancreatic Ductal / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D019175:DNA Methylation; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D015820:Cadherins; C108381:GEMIN2 protein, human; C533896:MIRN200 microRNA, human; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins