The first step in the development of human colorectal cancer is aberrant activation of the Wnt signaling pathway. Wnt signaling hyperactivation is predominantly caused by loss-of-function mutations in the adenomatous polyposis coli (APC) gene that encodes the pathway negative regulator. In order to identify genes affected by the Apc loss, we performed expression profiling of intestinal epithelium isolated from mice harboring a conditional Apc allele. The gene encoding transcriptional factor msh homeobox 1 (Msx1) displayed robust upregulation upon Apc inactivation. Histological analysis of the Apc-deficient epithelium revealed that in the small intestine, the Msx1 protein was localized exclusively in ectopic crypts, i.e., in pockets of proliferating cells abnormally positioned on the villi. Ablation of the Msx1 gene leads to the disappearance of ectopic crypts and loss of differentiated cells. Moreover, tumors arising from Msx1-deficient cells display altered morphology reminiscent of villous adenomas. In human tumor specimens, MSX1 displayed significantly increased expression in colonic neoplasia with a descending tendency during the lesion progression towards colorectal carcinoma. In summary, the results indicate that Msx1 represents a novel marker of intestinal tumorigenesis. In addition, we described the previously unknown relationship between the Msx1-dependent formation of ectopic crypts and cell differentiation.

Institute of Molecular Genetics of the Czech Academy of Sciences Videnska 1083 142 20 Prague 4 Czech Republic

Institute of Molecular Genetics of the Czech Academy of Sciences Videnska 1083 142 20 Prague 4 Czech Republic Department of Radiotherapy and Oncology 3rd Faculty of Medicine Charles University Prague Srobarova 50 100 34 Prague 10 Czech Republic

Institute of Molecular Genetics of the Czech Academy of Sciences Videnska 1083 142 20 Prague 4 Czech Republic Faculty of Science Charles University Prague Albertov 6 128 43 Praha 2 Czech Republic

Citace poskytuje Crossref.org