title: Claudin 1 in breast tumorigenesis: revelation of a possible novel "claudin high" subset of breast cancers.
abstract: Claudins are the major component of the tight junctions in epithelial cells and as such play a key role in the polarized location of ion channels, receptors, and enzymes to the different membrane domains. In that regard, claudins are necessary for the harmonious development of a functional epithelium. Moreover, defective tight junctions have been associated with the development of neoplastic phenotype in epithelial cells. Breakdown of cell-cell interactions and deregulation of the expression of junctional proteins are therefore believed to be key steps in invasion and metastasis. Several studies suggest that the claudins are major participants in breast tumorigenesis. In this paper, we discuss recent advances in our understanding of the potential role of claudin 1 in breast cancer. We also discuss the significance of a subset of estrogen receptor negative breast cancers which express "high" levels of the claudin 1 protein. We propose that claudin 1 functions both as a tumor suppressor as well as a tumor enhancer/facilitator in breast cancer.
authors.affiliation: Department of Pathology, University of Manitoba, Winnipeg, Manitoba, Canada R3E0W3. myal@cc.umanitoba.ca
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Myal
authors.forename: Etienne
authors.initials: E
authors.lastname: Leygue
authors.forename: Anne A
authors.initials: AA
authors.lastname: Blanchard
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D062445:Claudin-1; D018450:Disease Progression; D004967:Estrogens / Q000378:metabolism; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D010641:Phenotype; D011960:Receptors, Estrogen / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1; D004967:Estrogens; D008565:Membrane Proteins; D011960:Receptors, Estrogen