title: The EGFR-GEP100-Arf6 pathway in breast cancer: Full invasiveness is not from the inside.
abstract: Arf6 and its effector AMAP1 are overexpressed in malignant breast cancer cells, and are involved in their invasion and metastasis. We recently revealed that GEP100, a guanine nucleotide exchanging factor, is responsible for the activation of Arf6 which induces invasion and metastasis. GEP100 associated directly with ligand-activated epidermal growth factor receptor (EGFR) to be activated. Disruption of E-cadherin-mediated cell-cell adhesion is one of the major steps involved in acquisition of invasive phenotypes of most carcinomas. The EGFR-GEP100-Arf6 pathway not only activated matrix invasion activity but also perturbed E-cadherin function. GEP100 was found to be expressed in more than 80% of invasive ductal carcinomas. However, 60% of ductal carcinomas in situ were also positive for GEP100, in which GEP100 was preferentially coexpressed with EGFR in their malignant cases. Microenvionments have been highly implicated in the development of tumor malignancy. Our results reveal an aspect of the precise molecular mechanism of cancer invasion and metastasis, in which full invasiveness is not acquired just by alterations of cancer cells themselves, but their microenvironments may also play pivotal roles.
authors.affiliation: Department of Molecular Biology, Osaka Bioscience Institute, Suita, Osaka, Japan. sabe@obi.or.jp
authors.forename: Hisataka
authors.initials: H
authors.lastname: Sabe
authors.forename: Shigeru
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Morishige
authors.forename: Ari
authors.initials: A
authors.lastname: Hashimoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Ogawa
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D066246:ErbB Receptors / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D009361:Neoplasm Invasiveness / Q000473:pathology; D015398:Signal Transduction
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D066246:ErbB Receptors; D020727:ADP-Ribosylation Factors