BDNF expression and systemic dissemination via anoikis resistance in gastric cancer.

Abstract

e14541 Background: Anoikis (apoptosis resulting from loss of cell-matrix interaction) has been suggested to act as a physiological barrier to metastasis, and resistance to anoikis is necessary for cancer cell survival during systemic dissemination and metastasis. Brain-derived neurotrophic factor (BDNF) is one of the member of neurotropin family known to activate the high affinity tyrosine kinase (Trk)B receptor as a specific suppressor of anoikis. TrkB activation by BDNF has been shown to facilitate the progression of several cancers, however no reports have shown the clinical and biological effects of BDNF/TrkB axis in gastric cancer. Methods: BDNF expression in gastric cancer tissue and clinicopathological data from 153 consective patients were analyzed by real-time PCR and immunohistochemistry. The extent of target gene expression was calculated from the standard curve, with quantitative normalization of the cDNA in each sample performed using GAPDH gene as an internal control. Recombinant human BDNF and Trk antagonist K252a were used for in vitro assays to evaluate the biological role of the BDNF/TrkB axis in gastric cancer cell lines. Results: The mean BDNF level in gastric cancer tissue was 284.5 (0-2834). One hundred eighteen (77.1%) of 153 patients showed detectable BDNF levels, whereas the remainder had no detectable. BDNF positive expression was significantly associated with histological diffuse type (p=0.019), lymph node metastasis (p<0.001), peritoneal dissemination (p=0.028) and poor prognosis (p=0.022). In addition, BDNF expression is an independent risk factor for lymph node metastasis and peritoneal dissemination. Immunohistochemical analysis indicated intense BDNF expression in the cytoplasm of cancer cells, and intense TrkB expression in the nuclei of cancer cells, respectively. In vitro, administration of recombinant human BDNF promoted proliferation, anoikis resistance, and partial migration. In addition, these effects were generally inhibited by Trk antagonist K252a. Conclusions: BDNF appears to play an important role in gastric cancer progression, and blocking BDNF/TrkB axis might be clinically useful in developing therapies for patients with gastric cancer.