Potential Tumor Suppressor Protein: Expression and Function in Human Breast Cancer Cells

摘要

In a search for genes with a role in hormonal control of cell proliferation, we cloned a novel progestin-induced gene, EDD (previously DD5) that appears to be the human homologue of the hyd tumor suppressor gene of Drosophila melanogaster. By amino acid homology with other known proteins it is likely that the EDD protein is an E3 ubiquitin-protein ligase, enzymes which target one or more key proteins for destruction by ubiquitin- mediated proteolysis. The interaction between EDD and two potential ubiquitination substrates was further confined%. EDD was found to contain 2 nuclear localization signals both of which confer ability to interact with the nuclear import molecule importin alpha1. This was supported by the expression of green fluorescent protein-EDD fusion protein visualized predominantly in the nucleus of several cell types. A new system for inducible mammalian expression of EDD was tested and EDD cDNA from 26 breast, ovarian and prostate cancer cell lines was sequenced to determine the frequency of mutations in the EDD gene. Two high quality publications will result from this work.