Scientific Abstract

Proposal No. IBD-0230R2
Principal Investigator: JeanMarie Houghton, M.D., Ph.D.
Applicant Organization: University of Massachusetts Medical School
Project Title: Investigation of bone marrow derived stem cell recruitment to the colon in inflammatory bowel disease; direct and indirect role in carcinogenesis
Award Period: July 1, 2008 – December 31, 2010

Colon cancer arising in the setting of colitis is directly related to inflammation.

Inflammation has been linked with the initiation and progression of cancer through various mechanisms including direct growth effects of cytokines and chemokines on cancer cells and through recruiting and expanding populations of non-cancer cells, which become blood vessels and cancer associated fibroblasts within tumor stroma. Recent experimental data supports the notion that bone marrow derived cells (BMDC) are recruited to areas of inflammation and participate in tissue repair in response to a variety of signals emanating from the local inflammatory response. Once within the tissue, these cells can engraft and participate in tissue remodeling as both epithelial cells and stromal cells. Our group has shown that BMDCs migrate to areas of inflammation, and in the stomach transdifferentiate to epithelial cells and transform to cancer cells. In a similar manner, we hypothesize that BMDC within the colon in inflammatory bowel disease contribute to cancer formation through direct and indirect mechanisms. We have created a unique mesenchymal stem cell line, which allows us to inject trackable cells without prior myloablation of the host. We will follow the fate and contribution of the MSC to mucosal regeneration, metaplasia, dysplasia and neoplasia using two complimentary models of colitis; the IL-10 KO and DSS models. A role for direct transdifferentiation of BMDC to malignant colonic epithelium as well as the role for BMDC as stomal cells will be investigated using direct fluorescent imaging, immunohistochemistry and X/Y FISH analysis. The Fusion of MSC with host cells will be evaluated using a series of lox-P constructs injected into constitutively active, or promoter specific cre- mouse lines. MSC have been engineered with a reporter construct (ZEG, a kind gift from Dr. Lobe) which constitutively expresses beta-galactosidase. Lox-P sites flank the b-gal and a stop site. Fusion of the ZEG-MSC with a cre recombinase expressing cell will remove the b-gal and stop, placing GFP under control of the CMV promoter, thus converting the cell from b-gal expressing to GFP expressing. In order to determine the fusion partner for the MSC, CMV-cre (all cells express cre) and K-19-cre (intestinal cells express cre) mice will be used. MSC engraftment will be evaluated using direct fluorescent microscopy, immunohistochemistry, and in vivo imaging. The ability of the engrafted MSC to initiate and propagate tumors at secondary sites will be determined by injection of host, MSC and fused host/MSC populations in a subcutaneous mouse tumor model. Determining the role of MSC in colitis associated cancer will provide the groundwork for identifying unique identifiers, which may provide targets for designing new therapeutic agents.