Abstract. 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 upregulated 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.
Introductiongastric cancer (gc) is the fourth most prevalent malignancy worldwide and remains the second most common cause of cancer-related death globally. The distribution of gc is not uniform between different populations, as the prevalence in east asia, including Japan and china (where 42% of cases occur), eastern europe and South america is higher than elsewhere (1). The prognosis of gc is poor, with an estimated relative 5-year survival rate of less than 20% (2).gastric cancer is a genetic disease that develops from a multi-step process (3). Single or multiple mutations in genes related to growth control, apoptosis, invasion and metastasis form the molecular genetic basis of malignant transformation and tumor progression (4). Therefore, a better understanding of the molecular basis of tumor-host interactions may lead to significant progress in the development of new therapeutic agents.The discovery of mirnas has been a landmark milestone in molecular biology. mirnas can post-transcriptionally regulate the expression of hundreds of their target genes, thereby controlling a wide range of biological functions, such as cellular proliferation (5), differentiation (6) and apoptosis (7). recent evidence indicates that mirnas may function as tumor suppressors or oncogenes, and that alterations in mirna expression may play a critical role in tumorigenesis and cancer progression (8,9). mirnas have been found to be involved in known oncogenic pathways, including the p53 (10,11), Bcl2 (12) and k-ras (13) pathways. Finally, mirnas appear to be markedly significant prognostic factors in patients with various tumors (14-17), and could be useful ...