title: Identification of a genetic interaction between the tumor suppressor EAF2 and the retinoblastoma protein (Rb) signaling pathway in C. elegans and prostate cancer cells.
abstract: The tumor suppressor EAF2 is regulated by androgen signaling and associated with prostate cancer. While EAF2 and its partner ELL have been shown to be members of protein complexes involved in RNA polymerase II transcriptional elongation, the biologic roles for EAF2 especially with regards to the development of cancer remains poorly understood. We have previously identified the eaf-1 gene in Caenorhabditiselegans as the ortholog of EAF2, and shown that eaf-1 interacts with the ELL ortholog ell-1 to control development and fertility in worms. To identify genetic pathways that interact with eaf-1, we screened RNAi libraries consisting of transcription factors, phosphatases, and chromatin-modifying factors to identify genes which enhance the effects of eaf-1(tm3976) on fertility. From this screen, we identified lin-53, hmg-1.2, pha-4, ruvb-2 and set-6 as hits. LIN-53 is the C. elegans ortholog of human retinoblastoma binding protein 4/7 (RBBP 4/7), which binds to the retinoblastoma protein and inhibits the Ras signaling pathway. We find that lin-53 showed a synthetic interaction with eaf-1(tm3976) where knockdown of lin-53 in an eaf-1(tm3976) mutant resulted in sterile worms. This phenotype may be due to cell death as the treated worms contain degenerated embryos with increased expression of the ced-1:GFP cell death marker. Further we find that the interaction between eaf-1 and lin-53/RBBP4/7 also exists in vertebrates, which is reflected by the formation of a protein complex between EAF2 and RBBP4/7. Finally, overexpression of either human EAF2 or RBBP4 in LNCaP cells induced the cell death while knockdown of EAF2 in LNCaP enhanced cell proliferation, indicating an important role of EAF2 in controlling the growth and survival of prostate cancer cells. Together these findings identify a novel physical and functional interaction between EAF2 and the Rb pathway.
authors.affiliation: Department of Urology, The University of Pittsburgh, 5200 Centre Avenue, Pittsburgh, PA 15216, United States.
authors.forename: Liquan
authors.initials: L
authors.lastname: Cai
authors.affiliation: Department of Urology, The University of Pittsburgh, 5200 Centre Avenue, Pittsburgh, PA 15216, United States.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Division of Geriatrics, Gerontology, and Palliative Medicine, Department of Medicine, UTHSCSA, San Antonio, TX 78229, United States; Center for Healthy Aging, UTHSCSA, San Antonio, TX 78229, United States; GRECC, STVAHCS, San Antonio, TX 78229, United States. Electronic address: fishera2@uthscsa.edu.
authors.forename: Alfred L
authors.initials: AL
authors.lastname: Fisher
authors.affiliation: Department of Urology, The University of Pittsburgh, 5200 Centre Avenue, Pittsburgh, PA 15216, United States; GRECC, STVAHCS, San Antonio, TX 78229, United States. Electronic address: wangz2@upmc.edu.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000235:genetics* / Q000378:metabolism; D056505:Retinoblastoma-Binding Protein 4 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; C472771:EAF2 protein, human; C116486:LIN-53 protein, C elegans; C082637:RBBP4 protein, human; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; D056505:Retinoblastoma-Binding Protein 4; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
keywords: Apoptosis; C. elegans; RNAi library screen; Retinoblastoma protein; The tumor suppressor EAF2; lin-53
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