High FoxP3 expression in tumour cells predicts better survival in gastric cancer and its role in tumour microenvironment

BACKGROUND: Forkhead Box P3 (FoxP3) is thought to be a key transcription factor in regulatory T cells (Tregs), and recent data indicate that it is expressed in several tumour cells. However, its precise roles in gastric cancer (GC) and the underlying mechanisms regulating the interaction between GC cells and lymphocytes remain unclear. METHODS: FoxP3 expression was examined in tumour cells and Tregs in 150 cases of gastric precancer and cancer, and their prognostic significances were evaluated, respectively, using a tissue microarray containing 135 GC patient samples with a mean 102-month follow-up. FoxP3 involvement in the tumour cells–lymphocytes interaction and its gene function were further investigated. RESULTS: strong cytoplasmic staining of FoxP3 was observed in GC cells. FoxP3 protein expression in tumour cells predicts a good prognosis, whereas high-density Treg predicts a poor prognosis. Moreover, FoxP3 expression in GC cells increased after coculture with peripheral blood mononuclear cells through coculture systems. Upregulation of FoxP3 inhibited tumour growth in tumour-bearing nude mice. CONCLUSIONS: High FoxP3 expression in tumour cells predicts better survival in GC, possibility in relation to interaction between tumour cells and lymphocytes in microenvironment. Interfering with FoxP3 expression may open a new therapeutic strategy against tumour progression.