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.

Acquired cisplatin resistance in human ovarian A2780 cancer cells correlates with shift in taurine homeostasis and ability to volume regulate

“…In congruence we find that the impairment of swelling-induced taurine efflux and ability to volume regulate observed in cisplatin resistance in A2780 cells correlate with a decreased protein level of LRRC8A. LRRC8A mRNA is also reduced in RES A2780 cells compared with WT A2780 cells although not to the same extent as the LRRC8A protein expression, indicating that posttranslational ubiquitination and degradation of LRRC8A could be increased during acquirement of cisplatin resistance in A2780 cells as indicated by Bradley et al (2). It is assumed that the functional VSOAC transport pathway is formed by six proteins from the LRRC8 family and that shift in stoichiometry of LRRC8A and other LRRC8 members affects channel activity (62).…”

“…This eventually leads to G 2 cell cycle arrest and apoptosis. Chemotherapeutic resistance towards cisplatin involves 1) reduced intracellular drug accumulation following activity shift in membrane bound cisplatin carriers [MATE (multidrug and toxin extrusion), CRT1 (copper transporter 1), and OCT (organic cation transporter) [1][2][3] and ATPbinding cassette drug pumps, 2) enhanced drug detoxification, 3) improved DNA repair, 4) enhanced DNA damage tolerance, and finally 5) diminishing in the initiation/execution of the apoptotic cell death process (5,7,8,16,25,43).…”

AAV9 delivering a modified human Mullerian inhibiting substance as a gene therapy in patient-derived xenografts of ovarian cancer

“…Some of the limitations of PDXas are the serial passaging of the tumors, which can be lengthy and cause loss of clonal diversity, and replacement of human stroma and human vasculature (27,28). Methods that establish primary cell lines and PDXas in parallel allow for faster in vivo and in vitro testing that could direct therapeutic strategies for individual patients in real time (19,(29)(30)(31)(32), making ascites an ideal source of material for xenografts, which we distinguished from biopsy PDXs by referring to them as PDXas. Ascites can be obtained less invasively throughout the clinical course of the disease (33), are abundant and amenable to direct engraftment in a large number of mice, and often grow in tissue culture, allowing for parallel in vitro analyses.…”

Cellular Deficiency in the Rgs10 Protein Facilitates Chemoresistant Ovarian Cancer

“…For example, the presence of abundant E3 ubiquitin ligase facilitates platinum resistance, but its knockdown can also cause ovarian cancer cells to become 24-fold more sensitive to cisplatin [20]. In addition, cystathionine-β-synthase (a sulfur metabolism enzyme in primary serous) silencing in an orthotopic model resistant to cisplatin was able to resensitize the ovarian cancer cells to cisplatin [21].…”