SPROUTY2 is a beta-catenin and FOXO3a target gene indicative of poor prognosis in colon cancer
SPROUTY2 (SPRY2) is an intracellular regulator of receptor tyrosine kinase signaling involved in cell growth, differentiation and tumorigenesis. Here, we show that SPRY2 is a target gene of the Wnt/beta-catenin pathway that is abnormally activated in more than 90% of colon carcinomas. In human colon cancer cells, SPRY2 expression is induced by beta-catenin in co-operation with the transcription factor FOXO3a instead of lymphoid enhancer factor/T-cell factor proteins. We found binding of beta-catenin to the SPRY2 promoter at FOXO3a response elements. In vivo, cells marked by nuclear beta-catenin and FOXO3a express SPRY2 in proliferative epithelial tissues, such as intestinal mucosa and epidermis. Consistently, inducible beta-catenin deletion in mice reduced Spry2 expression in the small intestine. Moreover, SPRY2 protein expression correlated with nuclear beta-catenin and FOXO3a colocalization in human colon carcinomas. Importantly, the amount of SPRY2 protein correlated with shorter overall survival of colon cancer patients. Our data reveal SPRY2 as a novel Wnt beta-catenin and FOXO3a target gene indicative of poor prognosis in colon cancer.