Potential Role of the Tumor Suppressor ADENOMATOUS POLYPOSIS COLT in Polarization of Breast Epithelial Cells
Annual rept. 15 Jul 97-14 Jul 98
UTAH UNIV SALT LAKE CITY
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Recent evidence suggests that the adenomatous polyposis coli APC gene participates in breast tumorigenesis. Although a precise biological function for APC protein has not yet been determined, it has been shown that the APC protein interacts with beta-catenin and plakoglobin in vivo. Beta-catenin and plakoglobin are components of two specialized anchoring junctions, the adherens junction, a site of attachment for bundles of actin filaments, and the desmosome, a site of attachment for intermediate filaments e.g., keratin. A direct correlation has been shown between loss of adherens junction components and the metastatic potential of breast cancer. I have used a combination of immunofluorescence microscopy and biochemical fractionation to determine the location of APC protein in epithelial cells from both normal and breast cancer tissue. APC protein located at the cell-cell junctions of MCF-7 cells co-localized with E-cadherin, beta-catenin, and plakoglobin. Primary breast cells, deficient in APC protein did not form polarized structures when grown in matrigel. Mouse embryonic stem cells either heterozygous or homozygous for an APC mutation did not form embryoid bodies as efficiently as their normal parental counterparts. These findings are consistent with APC protein interacting with cell-cell junction proteins and effecting polarization.
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- Medicine and Medical Research