Isolierung von Tumorstammzellen aus Kolonkarzinomen
Final Report Abstract
During my stay at Dr. Ramesh Shivdasani’s lab at the Dana-Farber Cancer Institute, I mainly worked on the topic of colon cancer stem cells. The initial idea was to characterize and use a panel of monoclonal antibodies raised against LGR5, a stem cell marker of the normal colonic crypt epithelium, for prospective isolation of colon cancer stem cells by flow sorting. Although we obtained antibody clones that specifically detected LGR5, further efforts in this project were profoundly limited by low endogenous LGR5 protein expression levels in colon cancer cells. These did not allow their antibody based extraction from colon cancer xenografts by flow sorting. Looking for other ways to extract putative colon cancer stem cells, I constructed lentiviral WNT reporters that we successfully used for the extraction of a highly WNT-active tumor cell subpopulation, characterized by strong expression of several putative stem cell antigens, including LGR5. However, our data revealed that high WNT activity and expression of stem cell markers does not generally signify high or exclusive tumorigenic potential of colon cancer cells, thus questioning a recently published paradigm on this issue. Additionally, we could demonstrate that MAPK signaling strongly modulates intratumoral WNT activity and expression of markers designating putative colon cancer stem cell phenotypes. As a side project I characterized a knockout mouse model for the transcription factor gene Spdef. We could show the requirement of this gene in stomach epithelial homeostasis, protecting animals from gastric antral inflammation and subsequent reactive hyperplasia and propose a general role for this gene in secretory cell lineage maturation of the gastrointestinal tract.
Publications
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Requirement of the epithelial-specific ETS transcription factor Spdef for mucous gland cell function in the gastric antrum. J Biol Chem. 2010 Nov 5;285(45):35047-55
Horst D, Gu X, Bhasin M, Yang Q, Verzi M, Lin D, Joseph M, Zhang X, Chen W, Li YP, Shivdasani RA, Libermann TA
