Brain-derived neurotrophic factor downregulation in gastric cancer

The brain-derived neurotrophic factor (BDNF) is a certain type of growth factor that participates in the correct construction of the brain. Moreover, some reports have shown its participation in the tumorigenesis process. A long noncoding RNA known as BDNF-antisense (BDNF-AS) is shown to be transcribed from the antisense direction of the BDNF gene and control its expression. In the current study, we compared expression levels of BDNF and its antisense in gastric cancer tissues and adjacent noncancerous tissues (ANCTs) using quantitative real-time polymerase chain reaction. Expression of both genes tended to decrease in gastric cancer tissues in comparison with ANCTs (expression ratio = 0.4 and P = .06 for BDNF; expression ratio = 0.35 and P = .05 for BDNF-AS, respectively). Relative transcript levels of both genes were remarkably associated with the site of primary tumor in a way that all cardia tumors had low levels of both BDNF and BDNF-AS in comparison with their paired ANCTs (P = .002 and P = <.001). We also found higher amounts of both genes in malignant samples obtained from older patients (P = .01 and P = .03 for BDNF and BDNF-AS, respectively). Besides, BDNF expression was higher in tumors with lymphatic/vascular invasion (P = .01). There was also a trend toward upregulation of BDNF-AS in tumors with lymphatic/vascular invasion (P = .05). The current study underscores the role of BDNF and BDNF-AS in the pathogenic process leading to gastric cancer.