title: Overexpression and delocalization of claudin-3 protein in MCF-7 and MDA-MB-415 breast cancer cell lines.
abstract: Tumor-specific deregulated expression of claudins, integral membrane proteins found in tight junctions (TJs), has indicated a possible role for TJ disruption in cancer progression. The current study demonstrates the marked overexpression of claudin-3 protein in two breast cancer cell lines of metastatic origin (MCF-7 and MDA-MB-415). Immunofluorescence and differential detergent fractionation analyses revealed that, although claudin-3 was primarily localized at cell junctions, it was also detected intracellularly. Similarly, the siRNA-mediated suppression of claudin-3 did not considerably affect its pattern of subcellular distribution relative to mock-transfected cells. However, there appeared to be a preferential loss of claudin-3 signal in the cytoskeletal fraction. Wound-healing assays were conducted to assess the effect of endogenous overexpression versus siRNA-mediated suppression of claudin-3 on cellular motility in MCF-7 cells. Suppression of claudin-3 protein levels resulted in a marked decrease in the rate of cellular motility relative to mock-transfected cells. These findings suggest that overexpression of claudin-3 may be important in disrupting TJ integrity and thus contribute to enhanced cellular motility, a key component of tumor progression.
authors.affiliation: Biology Department, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Todd
authors.affiliation: Biology Department, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Petty
authors.affiliation: Biology Department, Trinity University, San Antonio, TX 78212, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: King
authors.affiliation: Biology Department, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Brytanie N
authors.initials: BN
authors.lastname: Piana Marshall
authors.affiliation: Biology Department, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Sheller
authors.affiliation: Biology Department, Southwestern University, Georgetown, TX 78626, USA.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Cuevas
keywords: cell motility; metastasis; tight junctions