A Myc-repressed miRNA signature distinguishes gastric DLBCL from low-grade MALT lymphoma. (A) The expression of 795 human mature miRNAsincluded in Version 10.0 of the miRBase database was analyzed for 7 cases of gastritis (green), 8 cases of low-grade MALT lymphoma (MALT-L; blue), and 7 gDLBCL cases (purple) with the use of microarray technology. The result of unsupervised hierarchical clustering of all miRNAs that varied across the 22 arrays with a standard deviation of log₂ expression > 0.05 is shown in the heat diagram. All known Myc-repressed miRNAs with lower expression in gDLBCL compared with low-grade MALT-L are annotated along with their fold change in expression (averaged across groups) between gDLBCL and MALT-L (in brackets). (B-C) Quantification of let-7a (B) and miR-34a (C) expression in the samples shown in panel A by LNA real-time RT-PCR; absolute expression was normalized to U6 snRNA. P values were calculated by unpaired t test. Horizontal lines represent median values. (D-E) Quantification of let-7a (D) and miR-34a (E) expression in matched MALT-L and gDLBCL samples from 3 patients with gastric lymphoma.