Dkk-1 secreted by mesenchymal stem cells inhibits growth of breast cancer cells via depression of Wnt signalling

We determined the molecular mechanism of inhibitory effect of human mesenchymal stem cells (hMSCs) on the growth of human MCF-7 breast cancer cells. Our finding showed that beta-catenin was down-regulated in MCF-7 cells by conditioned media from D hMSCs, and the expression level of dickkopf-1 (Dkk-1) was higher in Z3 cells than that in MCF-7 cells. Neutralization of Dkk-1 and small interference RNA targeting Dkk-1 mRNA in Z3 cells attenuated the inhibitory effect of D cells on MCF-7 cells. Overexpression of Dkk-1 in Z3 cells enhanced the inhibition. Therefore, Dkk-1 secreted by Z3 cells involves the inhibition via the Writ pathway. Crown copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.