ABSTRACT
Xanthatin, a xanthanolide sesquiterpene lactone isolated from Xanthium strumarium L. (Asteraceae), has prominent anti-tumor activity. Initial mechanism of action studies suggested xanthatin triggered activation of Wnt/ß-catenin. We examined the effects of xanthatin on signaling pathways in A459 lung cancer cells and mouse embryonic fibroblasts to ascertain requirements for xanthatin-induced cell death and tumor growth in xenografts. Genetic inactivation of GSK-3ß, but not the related isoform GSK-3α, compromised xanthatin cytotoxicity while inactivation of ß-catenin enhanced xanthatin-mediated cell death. These data provide insight into how xanthatin and related molecules could be effectively targeted toward certain tumors.
Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Carcinoma, Non-Small-Cell Lung/drug therapy , Furans/pharmacology , Glycogen Synthase Kinase 3 beta/metabolism , Lung Neoplasms/drug therapy , beta Catenin/metabolism , Animals , Cell Line, Tumor , Humans , Mice , Phosphorylation , Signal Transduction/drug effects , Tumor Cells, Cultured , Xanthium/chemistryABSTRACT
We developed the recombinant green fluorescent protein gene yeast cell to screen estrogenic compounds based on two episomal vectors. In the expression vector the expression of human estrogen receptor alpha(hERalpha) was driven by 3-glyceraldehydephosphate dehydrogenase (GPD) promoter; in the reporter vector the expression of the yeast enhanced green fluorescent protein (yEGFP) gene was under the control of the estrogen response element (ERE). The vectors were transformed into yeast cell (W303-1A) to construct GFP recombinant yeast cell. Incubation of the yeast cell with various concentrations of the estrogenic compounds led to expression of the reporter gene product GFP in a dose dependent manner. Compared to other yeast bioassays, the yeast cell for environmental estrogen bioassay based on yEGFP reporter gene did not need cell wall disruption or the addition of a substrate or reagent. This yEGFP assay was performed completely in 96 well plates. So this test system can be used as a rapid and high throughput system for screening estrogenic chemical products, which has the characteristics of the sensitivity, reproducibility and cheapness.
