title: Astrocyte elevated gene-1 (AEG-1) is a target gene of oncogenic Ha-ras requiring phosphatidylinositol 3-kinase and c-Myc.
abstract: It is well established that Ha-ras and c-myc genes collaborate in promoting transformation, tumor progression, and metastasis. However, the precise mechanism underlying this cooperation remains unclear. In the present study, we document that astrocyte elevated gene-1 (AEG-1) is a downstream target molecule of Ha-ras and c-myc, mediating their tumor-promoting effects. AEG-1 expression is elevated in diverse neoplastic states, it cooperates with Ha-ras to promote transformation, and its overexpression augments invasion of transformed cells, demonstrating its functional involvement in Ha-ras-mediated tumorigenesis. We now document that AEG-1 expression is markedly induced by oncogenic Ha-ras, activating the phosphatidylinositol 3-kinase signaling pathway that augments binding of c-Myc to key E-box elements in the AEG-1 promoter, thereby regulating AEG-1 transcription. In addition, Ha-ras-mediated colony formation is inhibited by AEG-1 siRNA. This is a demonstration that Ha-ras activation of a tumor-promoting gene is regulated directly by c-Myc DNA binding via phosphatidylinositol 3-kinase signaling, thus revealing a previously uncharacterized mechanism of Ha-ras-mediated oncogenesis through AEG-1.
authors.affiliation: Department of Urology, Columbia University Medical Center, College of Physicians and Surgeons, New York, NY 10032, USA.
authors.forename: Seok-Geun
authors.initials: SG
authors.lastname: Lee
authors.forename: Zao-Zhong
authors.initials: ZZ
authors.lastname: Su
authors.forename: Luni
authors.initials: L
authors.lastname: Emdad
authors.forename: Devanand
authors.initials: D
authors.lastname: Sarkar
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
mesh_terms: D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins; D015398:Signal Transduction
chemical_list: D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D016271:Proto-Oncogene Proteins c-myc; D016283:Proto-Oncogene Proteins p21(ras); D016601:RNA-Binding Proteins; C483039:MTDH protein, human