Abstract B88: Local delivery of breast cancer chemopreventives using mesenchymal stem cells

The overall goal of this study is to evaluate the ability of bone marrow mesenchymal stem cells (MSCs) to act as vehicles for local delivery of chemopreventives in mice that develop mammary cancer. Recently, efforts to use adult‐derived stem cells to deliver therapeutic agents to tumor sites have shown great promise and we currently are extending this concept to include the delivery of gene therapy in the form of chemopreventives. Our goals in this initial project were to (1) isolate and study the behavior of transplanted MSCs in mammary glands of mice and (2) develop a gene expression system which robustly produces gene therapeutics. For gene therapy we aimed to target epidermal growth factor (EGFR/ErbB1/HER1) because activation of this growth factor pathway is a frequent component driving breast cancer proliferation and survival and recent evidence demonstrated that the EGFR pathway is more active in hyperplastic enlarged lobules compared with normal terminal ductal lobular units (AJP 2007 171, 253–262), indicating that EGFR activation is a very early event that precedes cancer development and therefore inhibiting EGFR may abrogate cancer development. To carry out this goal we developed an expression system that produces the natural inhibitory ligand of EGFR, decorin. Decorin is a small leucine rich proteoglycan with known effects in extracellular matrix assembly as well as growth inhibition via reduction in levels and activity of EGFR along with other signaling molecules. Thus far we have demonstrated the ability to isolate, culture and maintain murine MSCs from the FVB/N strain in an undifferentiated state. In addition, these MSCS do not form tumors upon transplantation into mammary glands of syngeneic mice. Furthermore, we have produced secreted decorin in Chinese hamster ovarian cells and MSCs. Finally, we demonstrate the ability of conditioned media containing decorin to inhibit mammary tumor cell proliferation in vitro. Our long-term goal is to test the efficacy of decorin‐engineered MSCs as a breast cancer prevention modality in mouse models. Citation Information: Cancer Prev Res 2010;3(1 Suppl):B88.