A diterpenoid derivative 15-oxospiramilactone inhibits Wnt/Β-catenin signaling and colon cancer cell tumorigenesis

Abstract

The Wnt/Β-catenin signaling pathway is a highly conserved pathway in organism evolution and regulates many biological processes. Aberrant activation of the Wnt/Β-catenin signaling pathway is closely related to tumorigenesis. In order to identify potent small molecules to treat the over-activated Wnt signaling-mediated cancer, such as colon cancer, we established a mammalian cell line-based reporter gene screening system. The screen revealed a diterpenoid derivative, 15-oxospiramilactone (NC043) that inhibits Wnt3a or LiCl-stimulated Top-flash reporter activity in HEK293T cells and growth of colon cancer cells, SW480 and Caco-2. Treatment of SW480 cells with NC043 led to decreases in the mRNA and/or protein expression of Wnt target genes Axin2, Cyclin D1 and Survivin, as well as decreases in the protein levels of Cdc25c and Cdc2. NC043 did not affect the cytosol-nuclear distribution and protein level of soluble Β-catenin, but decreased Β-catenin/TCF4 association in SW480 cells. Moreover, NC043 inhibited anchorage-independent growth and xenograft tumorigenesis of SW480 cells. Collectively these results demonstrate that NC043 is a novel small molecule that inhibits canonical Wnt signaling downstream of Β-catenin stability and may be a potential compound for treating colorectal cancer. © 2011 IBCB, SIBS, CAS All rights reserved.