Studies on human colon cancer gene APC by targeted expression in Drosophila.
Mutations in human Adenomatous Polyposis Coli (APC) gene are associated with both familial and sporadic colorectal tumors. APC is known to down regulate beta-catenin levels, a transducer of Wnt signaling. The aim of this study is to provide transgenic Drosophila expressing either full-length or truncated forms of human APC (hAPC) protein and methods for using them in functional genomics and drug screening. Consistent with its biochemical properties, targeted expression of either full-length hAPC or its beta-catenin binding domain alone negatively regulated the function of the beta-catenin homologue, Armadillo (Arm) and thereby, inhibited Wnt/Wg signaling during fly development. hAPC inhibited Arm function even in the absence of GSK-3beta activity, although the latter was required to mediate the degradation of Arm. Consistent with this, hAPC suppressed the phenotypes induced by the over-expression of degradation-resistant forms of Arm. Subsequently, using hAPC-induced eye phenotypes as the assay in a suppressor-enhancer screen, we have identified two new loci in Drosophila, which modulate Wnt/Wg signaling. In addition, an anti-colon cancer drug, indomethacin, specifically enhanced hAPC-induced phenotypes.
Bhandari
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Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, India 500 007.
Shashidhara
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LS
D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000502:physiology*; D000818:Animals; D030801:Animals, Genetically Modified; D000970:Antineoplastic Agents / Q000494:pharmacology; D051186:Armadillo Domain Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics; D003598:Cytoskeletal Proteins / Q000502:physiology; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins; D004354:Drug Screening Assays, Antitumor; D005123:Eye / Q000033:anatomy & histology / Q000196:embryology / Q000648:ultrastructure; D018390:Gene Targeting; D017491:Genes, APC; D017344:Genes, Insect; D038362:Glycogen Synthase Kinase 3; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D019476:Insect Proteins / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000502:physiology; D015534:Trans-Activators; D014157:Transcription Factors; D014162:Transfection; D051155:Wnt1 Protein; D051176:beta Catenin
C495305:ARM protein, Drosophila; D025601:Adenomatous Polyposis Coli Protein; D000970:Antineoplastic Agents; D051186:Armadillo Domain Proteins; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051155:Wnt1 Protein; D051176:beta Catenin; C074622:wg protein, Drosophila; D017346:Protein Serine-Threonine Kinases; C080335:Sgg protein, Drosophila; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3; D007213:Indomethacin