p75 Neurotrophin Receptor Suppresses the Proliferation of Human Gastric Cancer Cells

Identifying an effective therapeutic target is pivotal in the treatment of gastric cancer. In this study, we in-vestigated the expression of p75 neurotrophin recep-tor (p75NTR) in gastric cancer and the impact of its alteration on tumor growth. p75NTR expression was absent or significantly decreased in 212 cases of gas-tric cancers compared with the normal gastric mucosa (P <.05). Moreover, p75NTR expression was also lost or significantly decreased in various human gastric cancer cell lines. p75NTR inhibited in vitro growth activities and caused dramatic attenuation of tumor growth in animal models by induction of cell cycle arrest. Upregulation of p75NTR led to downregulation of cyclin A, cyclin D1, cyclin E, cyclin-dependent ki-nase 2, p-Rb, and PCNA, but to upregulation of Rb and p27 expressions. Conversely, downregulating p75NTR with specific siRNA yielded inverse results. The res-cue of tumor cells from cell cycle progression by a death domain–deleted dominant-negative antagonist of p75NTR (#p75NTR) showed that the death do-main transduced antiproliferative activity in a ligand-independent manner and further demonstrated the inhibitive effect of p75NTR on growth in gastric cancer. Therefore, we provided evidence that p75NTR was a potential tumor suppressor and may be used as a therapeutic target for gastric cancer