title: Knockdown of astrocyte-elevated gene-1 inhibits prostate cancer progression through upregulation of FOXO3a activity.
abstract: Astrocyte-elevated gene-1 (AEG-1) has been reported to be upregulated in several malignancies and play a critical role in Ha-ras-mediated oncogenesis through the phosphatidylinositol 3-kinase/AKT signaling pathway. However, the role of AEG-1 in prostate cancer (PC) has never been reported. We now show that AEG-1 is overexpressed in clinical PC tissue samples and cultured PC cells compared to benign prostatic hyperplasia tissue samples and normal prostate epithelial cells. Interestingly, AEG-1 knockdown induced cell apoptosis through upregulation of forkhead box (FOXO) 3a activity. This alteration of FOXO3a activity was dependent on reduction of AKT activity in LNCaP and PC-3 cells with high constitutive AKT activity, but not in DU145 cells with low constitutive AKT activity, although AEG-1 knockdown had no impact on phosphatase and tensin homolog expression in these cells. AEG-1 knockdown also attenuated the constitutive activity of the nuclear factor kappaB (NF-kappaB) and the activator protein 1 (AP-1) with a corresponding depletion in the expression of NF-kappaB and AP-1-regulated genes (interleukin (IL)-6, IL-8 and matrix metalloproteinase-9) and significantly decreased cell invasion properties of PC-3 and DU145 cells. Overall, our findings suggest that aberrant AEG-1 expression plays a dominant role as a positive auto-feedback activator of AKT and as a suppressor of FOXO3a in PC cells. AEG-1 may therefore represent a novel genetic biomarker to serve as an attractive molecular target for new anticancer agents to prevent PC cell progression and metastasis.
authors.affiliation: Department of Urology, Veterans Affairs Medical Center and University of California, San Francisco, CA 94121, USA.
authors.forename: N
authors.initials: N
authors.lastname: Kikuno
authors.forename: H
authors.initials: H
authors.lastname: Shiina
authors.forename: S
authors.initials: S
authors.lastname: Urakami
authors.forename: K
authors.initials: K
authors.lastname: Kawamoto
authors.forename: H
authors.initials: H
authors.lastname: Hirata
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: R F
authors.initials: RF
authors.lastname: Place
authors.forename: D
authors.initials: D
authors.lastname: Pookot
authors.forename: S
authors.initials: S
authors.lastname: Majid
authors.forename: M
authors.initials: M
authors.lastname: Igawa
authors.forename: R
authors.initials: R
authors.lastname: Dahiya
mesh_terms: D017209:Apoptosis / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D018450:Disease Progression; D015536:Down-Regulation; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016601:RNA-Binding Proteins; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D015815:Cell Adhesion Molecules; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C483039:MTDH protein, human; D008565:Membrane Proteins; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D016601:RNA-Binding Proteins; D018808:Transcription Factor AP-1; D051057:Proto-Oncogene Proteins c-akt