Generation and characterization of an inducible transgenic model for studying mouse esophageal biology

Background: To facilitate the in vivo study of esophageal (stem) cell biology in homeostasis and cancer, novel mouse models are necessary to elicit expression of candidate genes in a tissue-specific and inducible fashion. To this aim, we developed and studied a mouse model to allow labeling of esophageal cells with the histone 2B-GFP (H2B-GFP) fusion protein. Results: First, we generated a transgenic mouse model expressing the reverse tetracycline transactivator rtTA2-M2 under control of the promoter (ED-L2) of the Epstein-Barr virus (EBV) gene encoding the latent membrane protein-1 (LMP-1). The newly generated ED-L2-rtTA2-M2 (ED-L2-rtTA) mice were then bred with the previously developed tetO-HIST1H2BJ/GFP (tetO-H2B-GFP) model to assess inducibility and tissue-specificity. Expression of the H2B-GFP fusion protein was observed upon doxycycline induction but was restricted to the terminally differentiated cells above the basal cell layer. To achieve expression in the basal compartment of the esophagus, we ubsequently employed a different transgenic model expressing the reverse transactivator rtTA2S-M2 under the control of the ubiquitous, methylation-free CpG island of the human hnRNPA2B1-CBX3 gene (hnRNP-rtTA). Upon doxycycline administration to the compound hnRNP-rtTA/tetO-H2B-GFP mice, near-complete labeling of all esophageal cells was achieved. Pulse-chase experiments confirmed that complete turnover of the esophageal epithelium in the adult mouse is achieved within 710 days. Conclusions: We show that the esophagus-specific promoter ED-L2 is expressed only in the differentiated cells above the basal layer. oreover, we confirmed that esophageal turn-over in the adult mouse does not exceed 710 days

Cancer Stemness in Apc- vs. Apc/KRAS-Driven Intestinal Tumorigenesis

Constitutive activation of the Wnt pathway leads to adenoma formation, an obligatory step towards intestinal cancer. In view of the established role of Wnt in regulating stemness, we attempted the isolation of cancer stem cells (CSCs) from Apc- and Apc/KRAS-mutant intestinal tumours. Whereas CSCs are present in Apc/KRAS tumours, they appear to be very rare (®-catenin intracellular stabilization

The CHEK2 1100delC mutation identifies families with a hereditary breast and colorectal cancer phenotype

Because of genetic heterogeneity, the identification of breast cancer-susceptibility genes has proven to be exceedingly difficult. Here, we define a new subset of families with breast cancer characterized by the presence of colorectal cancer cases. The 1100delC variant of the cell cycle checkpoint kinase CHEK2 gene was present in 18% of 55 families with hereditary breast and colorectal cancer (HBCC) as compared with 4% of 380 families with non-HBCC (P<.001), thus providing genetic evidence for the HBCC phenotype. The CHEK2 1100delC mutation was, however, not the major predisposing factor for the HBCC phenotype but appeared to act in synergy with another, as-yet-unknown susceptibility gene(s). The unequivocal definition of the HBCC phenotype opens new avenues to search for thi