Large intergenic noncoding RNAs (lincRNA) have been less studied than miRNAs in cancer, although both offer considerable theranostic potential. In this study, we identified frequent upregulation of miR-196a and lincRNA HOTAIR in high-risk gastrointestinal stromal tumors (GIST). Overexpression of miR-196a was associated with high-risk grade, metastasis and poor survival among GIST specimens. miR-196a genes are located within the HOX gene clusters and microarray expression analysis revealed that the HOXC and HOTAIR gene were also coordinately upregulated in GISTs which overexpress miR-196a. In like manner, overexpression of HOTAIR was also strongly associated with high-risk grade and metastasis among GIST specimens. RNA interference–mediated knockdown of HOTAIR altered the expression of reported HOTAIR target genes and suppressed GIST cell invasiveness. These findings reveal concurrent overexpression of HOX genes with noncoding RNAs in human cancer in this setting, revealing miR-196a and HOTAIR as potentially useful biomarkers and therapeutic targets in malignant GISTs. Cancer Res; 72(5); 1126–36. ©2012 AACR.

The efficacy of azathioprine for Crohn’s disease under adalimumab treatment remains obscure. In an open-labelled prospective study, we evaluated the efficacy of adalimumab with and without azathioprine in patients with active Crohn’s disease, who were naïve to biologics and thiopurines. The patients were randomly assigned to subcutaneous administration of adalimumab [monotherapy group] or to exactly the same schedule of adalimumab with azathioprine [25–100mg daily] [combination group] for 52 Weeks. The primary endpoint was clinical remission at WWeek 26. We also evaluated the score for simple endoscopic severity of Crohn’s disease before the therapy and at WWeeks 26 and 52. A total of 176 patients were randomized to either the monotherapy group [n = 85] or to the combination group [n = 91]. Eighteen patients [21.2%] from the monotherapy group and 7 patients [7.7%] from the combination group withdrew owing to active disease, and 15 patients [16.5%] from the combination group and 1 patient [1.2%] from the monotherapy group withdrew due to side effects of the medications. Non-responder imputation analysis revealed that the remission rate at WWeek 26 did not differ between the monotherapy group and the combination group [71.8% vs 68.1%; OR 0.84, p = 0.63]. The rate of endoscopic improvement at WWeek 26 was significantly higher in the combination group [84.2%, n = 57] than in the monotherapy group [63.8%, n = 58] [p = 0.019]. The clinical efficacy of a combination of adalimumab and azathioprine at WWeek 26 did not differ from that of adalimumab monotherapy in patients with Crohn’s disease naïve to both medications.

Activation of Wnt signaling has been implicated in tumorigenesis, and epigenetic silencing of Wnt antagonist genes has been detected in various cancers. In the present study, we examined the expression and methylation of DICKKOPF ( DKK ) family genes in gastrointestinal cancer cell lines. We found that all known DKK genes were frequently silenced in colorectal cancer (CRC) cells ( DKK1 , 3/9, 33%; DKK2 , 8/9, 89%; DKK3 , 5/9, 56% and DKK4 , 5/9, 56%), but not in normal colon mucosa. DKK1 , - 2 and - 3 have 5′ CpG islands, and show an inverse relation between expression and methylation. DKK methylation also was frequently observed in gastric cancer (GC) cell lines ( DKK1 , 6/16, 38%; DKK2 , 15/16, 94% and DKK3 , 10/16, 63%), but was seen less frequently in hepatocellular carcinoma and pancreatic cancer cell lines. DKK s also were frequently methylated in primary CRCs ( DKK1 , 7/58, 12%; DKK2 , 45/58, 78% and DKK3 , 12/58, 21%) and GCs ( DKK1 , 15/31, 48%; DKK2 , 26/31, 84% and DKK3 , 12/31, 39%). Against a background of CTNNB1 or APC mutations, Dickkopfs (Dkks) were less effective inhibitors of Wnt signaling than secreted frizzled-related proteins, though over-expression of Dkks suppressed colony formation of CRC cells with such mutations. Our results demonstrate that DKK s are frequent targets of epigenetic silencing in gastrointestinal tumors, and that loss of DKK s may facilitate tumorigenesis through β-catenin/T-cell factor-independent mechanisms.

Sessile serrated adenomas (SSAs) are known to be precursors of sporadic colorectal cancers (CRCs) with microsatellite instability (MSI), and to be tightly associated with BRAF mutation and the CpG island methylator phenotype (CIMP). Consequently, colonoscopic identification of SSAs has important implications for preventing CRCs, but accurate endoscopic diagnosis is often difficult. Our aim was to clarify which endoscopic findings are specific to SSAs. The morphological, histological and molecular features of 261 specimens from 226 colorectal tumors were analyzed. Surface microstructures were analyzed using magnifying endoscopy. Mutation in BRAF and KRAS was examined by pyrosequencing. Methylation of p16, IGFBP7, MLH1 and MINT1, -2, -12 and -31 was analyzed using bisulfite pyrosequencing. Through retrospective analysis of a training set (n=145), we identified a novel surface microstructure, the Type II open-shape pit pattern (Type II-O), which was specific to SSAs with BRAF mutation and CIMP. Subsequent prospective analysis of an independent validation set (n=116) confirmed that the Type II-O pattern is highly predictive of SSAs (sensitivity, 65.5%; specificity, 97.3%). BRAF mutation and CIMP occurred with significant frequency in Type II-O-positive serrated lesions. Progression of SSAs to more advanced lesions was associated with further accumulation of aberrant DNA methylation and additional morphological changes, including the Type III, IV and V pit patterns. Our results suggest the Type II-O pit pattern is a useful hallmark of the premalignant stage of CRCs with MSI and CIMP, which could serve to improve the efficacy of colonoscopic surveillance.

Altered expression of microRNA (miRNA) is strongly implicated in cancer, and recent studies have shown that the silencing of some miRNAs is associated with CpG island hypermethylation. To identify epigenetically silenced miRNAs in gastric cancer (GC), we screened for miRNAs induced by treatment with 5-aza-2’-deoxycytidine and 4-phenylbutyrate. We found that miR-34b and miR-34c are epigenetically silenced in GC and that their downregulation is associated with hypermethylation of the neighboring CpG island. Methylation of the miR-34b/c CpG island was frequently observed in GC cell lines (13/13, 100%) but not in normal gastric mucosa from Helicobacterpylori -negative healthy individuals. Transfection of a precursor of miR-34b and miR-34c into GC cells induced growth suppression and dramatically changed the gene expression profile. Methylation of miR-34b/c was found in a majority of primary GC specimens (83/118, 70%). Notably, analysis of non-cancerous gastric mucosae from GC patients ( n = 109) and healthy individuals ( n = 85) revealed that methylation levels are higher in gastric mucosae from patients with multiple GC than in mucosae from patients with single GC (27.3 versus 20.8%; P < 0.001) or mucosae from H. pylori -positive healthy individuals (27.3 versus 20.7%; P < 0.001). These results suggest that miR-34b and miR-34c are novel tumor suppressors frequently silenced by DNA methylation in GC, that methylation of miR-34b/c is involved in an epigenetic field defect and that the methylation might be a predictive marker of GC risk.