MicroRNA profiling of human gastric cancer

MicroRNAs are a group of small non-coding RNAs that modulate gene expression. The de-regulation of microRNA expression has been found in several types of cancer. To study the role of microRNAs in gastric cancer (GC), we analyzed the expression profile of 847 microRNAs in GC from Chinese patients. Total RNA was used for hybridization on the miRCURY LNA Array (v. 11.0), which contains probes specific for 847 human microRNAs. The results from the miRNA microarray analysis were validated by real-time RT-PCR. A total of 24 miRNAs with a more than 2-fold change were differentially expressed between normal gastric tissue and GC. Of these, 22 miRNAs (miR-223, miR-106b, miR-147, miR-34a, miR-130b*, miR-106a, miR-18a, miR-17, miR-98, miR-616*, miR-181a-2*, miR-185, miR-1259, miR-601, miR-196a*, miR-221*, miR-302f, miR-340*, miR-337-3p, miR-520c-3p, miR-575 and miR-138) were significantly up-regulated in GC (P<0.05), whereas only miR-638 and miR-378 were significantly down-regulated in GC (P<0.05) compared to normal gastric tissue. The expression of miR-185 and miR-638, as measured by miRNA microarray analysis, was in agreement with the expression level of these microRNAs found by real-time RT-PCR in the same samples. Our results show that microRNAs are de-regulated in GC, suggesting the involvement of these genes in the development and progression of gastric cancer.