title: TR3 modulates platinum resistance in ovarian cancer.
abstract: In metastatic ovarian cancer, resistance to platinum chemotherapy is common. Although the orphan nuclear receptor TR3 (nur77/NR4A1) is implicated in mediating chemotherapy-induced apoptosis in cancer cells, its role in ovarian cancer has not been determined. In an ovarian cancer tissue microarray, TR3 protein expression was elevated in stage I tumors, but downregulated in a significant subset of metastatic tumors. Moreover, TR3 expression was significantly lower in platinum-resistant tumors in patients with metastatic disease, and low TR3 staining was associated with poorer overall and progression-free survival. We have identified a direct role for TR3 in cisplatin-induced apoptosis in ovarian cancer cells. Nucleus-to-cytoplasm translocation of TR3 was observed in cisplatin-sensitive (OVCAR8, OVCAR3, and A2780PAR) but not cisplatin-resistant (NCI/ADR-RES and A2780CP20) ovarian cancer cells. Immunofluorescent analyses showed clear overlap between TR3 and mitochondrial Hsp60 in cisplatin-treated cells, which was associated with cytochrome c release. Ovarian cancer cells with stable shRNA- or transient siRNA-mediated TR3 downregulation displayed substantial reduction in cisplatin effects on apoptotic markers and cell growth in vitro and in vivo. Mechanistic studies showed that the cisplatin-induced cytoplasmic TR3 translocation required for apoptosis induction was regulated by JNK activation and inhibition of Akt. Finally, cisplatin resistance was partially overcome by ectopic TR3 overexpression and by treatment with the JNK activator anisomycin and Akt pathway inhibitor, wortmannin. Our results suggest that disruption of TR3 activity, via downregulation or nuclear sequestration, likely contributes to platinum resistance in ovarian cancer. Moreover, we have described a treatment strategy aimed at overcoming platinum resistance by targeting TR3.
authors.affiliation: Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Vanderbilt University School of Medicine, B1100 Medical Center North, Nashville, TN 37232, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wilson
authors.forename: Annie Y
authors.initials: AY
authors.lastname: Liu
authors.forename: Joseph
authors.initials: J
authors.lastname: Roland
authors.forename: Oluwafunmilayo B
authors.initials: OB
authors.lastname: Adebayo
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Fletcher
authors.forename: James C
authors.initials: JC
authors.lastname: Slaughter
authors.forename: Jeanette
authors.initials: J
authors.lastname: Saskowski
authors.forename: Marta A
authors.initials: MA
authors.lastname: Crispens
authors.forename: Howard W
authors.initials: HW
authors.lastname: Jones
authors.forename: Samuel
authors.initials: S
authors.lastname: James
authors.forename: Oluwole
authors.initials: O
authors.lastname: Fadare
authors.forename: Dineo
authors.initials: D
authors.lastname: Khabele
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005260:Female; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000378:metabolism*; D017671:Platinum Compounds / Q000627:therapeutic use; D021381:Protein Transport; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D046888:Tissue Array Analysis; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D017671:Platinum Compounds