Up-regulation of long noncoding RNA M26317 correlates with tumor progression and poor prognosis in gastric cancer

To investigate the expression and clinical significance of long noncoding RNA (lncRNA) in gastric cancer, we applied microarray analysis to obtain expression profiles of protein-coding genes and lncRNAs in tumor and paired adjacent nontumor tissues. We found that 41 lncRNAs were up-regulated and 31 lncRNAs were down-regulated more than 2-fold in gastric cancer versus noncancerous tissues (ratio >2.0, P < .01). We established a coexpression network of the differentially expressed lncRNAs and targeted coding genes that included 17 lncRNAs and 16 coding genes. Because the results of microarray analysis showed that lncRNA M26317 was up-regulated in gastric cancer tissues, we examined the expression level of M26317 in 103 gastric cancer tissues by reverse-transcription polymerase chain reaction and 436 gastric cancer tissues by in situ hybridization. Our data confirmed that M26317 was up-regulated in gastric cancer tissues. Moreover, expression of M26317 correlated with patient age, size of tumor, Lauren's classification, depth of invasion, lymph node and distant metastasis, TNM stage, and poor prognosis (P < .05), but was not associated with sex, location of tumor, and differentiation (P > .05). M26317 may have an important role in malignant transformation and metastasis of gastric cancer.