title: EDD enhances cell survival and cisplatin resistance and is a therapeutic target for epithelial ovarian cancer.
abstract: The E3 ubiquitin ligase EDD is overexpressed in recurrent, platinum-resistant ovarian cancers, suggesting a role in tumor survival and/or platinum resistance. EDD knockdown by small interfering RNA (siRNA) induced apoptosis in A2780ip2, OVCAR5 and ES-2 ovarian cancer cells, correlating with loss of the prosurvival protein myeloid cell leukemia sequence 1 (Mcl-1) through a glycogen synthase kinase 3 beta-independent mechanism. SiRNA to EDD or Mcl-1 induced comparable levels of apoptosis in A2780ip2 and ES-2 cells. Stable overexpression of Mcl-1 protected cells from apoptosis following EDD knockdown, accompanied by a loss of endogenous, but not exogenous, Mcl-1 protein, suggesting that EDD regulated Mcl-1 synthesis. Indeed, EDD knockdown induced a 1.87-fold decrease in Mcl-1 messenger RNA and EDD transfection enhanced murine Mcl-1 promoter-driven luciferase expression 5-fold. To separate EDD survival and potential cisplatin resistance functions, we generated EDD shRNA stable cell lines that could survive initial EDD knockdown and showed that these cells were 4- to 21-fold more sensitive to cisplatin. Moreover, transient EDD overexpression in COS-7 cells was sufficient to promote cisplatin resistance 2.4-fold, dependent upon its E3 ligase activity. In vivo, mouse intraperitoneal ES-2 and A2780ip2 xenograft experiments showed that mice treated with EDD siRNA by nanoliposomal delivery [1,2-dioleoyl-sn-glycero-3-phophatidylcholine (DOPC)] and cisplatin had significantly less tumor burden than those treated with control siRNA/DOPC alone (ES-2, 77.9% reduction, P = 0.004; A2780ip2, 75.9% reduction, P = 0.042) or control siRNA/DOPC with cisplatin in ES-2 (64.4% reduction, P = 0.035), with a trend in A2780ip2 (60.3% reduction, P = 0.168). These results identify EDD as a dual regulator of cell survival and cisplatin resistance and suggest that EDD is a therapeutic target for ovarian cancer.
authors.affiliation: Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Amber
authors.initials: A
authors.lastname: Bradley
authors.forename: Hui
authors.initials: H
authors.lastname: Zheng
authors.forename: Angela
authors.initials: A
authors.lastname: Ziebarth
authors.forename: Wayne
authors.initials: W
authors.lastname: Sakati
authors.forename: Melissa
authors.initials: M
authors.lastname: Branham-O'Connor
authors.forename: Joe B
authors.initials: JB
authors.lastname: Blumer
authors.forename: Yuying
authors.initials: Y
authors.lastname: Liu
authors.forename: Emily
authors.initials: E
authors.lastname: Kistner-Griffin
authors.forename: Cristian
authors.initials: C
authors.lastname: Rodriguez-Aguayo
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lopez-Berestein
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
authors.forename: Charles N
authors.initials: CN
authors.lastname: Landen
authors.forename: Scott T
authors.initials: ST
authors.lastname: Eblen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D000077216:Carcinoma, Ovarian Epithelial; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000235:genetics / Q000378:metabolism; D009375:Neoplasms, Glandular and Epithelial / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D059748:Proteolysis; D014158:Transcription, Genetic; D044767:Ubiquitin-Protein Ligases / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C117617:UBR5 protein, human; D044767:Ubiquitin-Protein Ligases; D002945:Cisplatin