title: Aberrant DNA damage response pathways may predict the outcome of platinum chemotherapy in ovarian cancer.
abstract: Ovarian carcinoma (OC) is the most lethal gynecological malignancy. Despite the advances in the treatment of OC with combinatorial regimens, including surgery and platinum-based chemotherapy, patients generally exhibit poor prognosis due to high chemotherapy resistance. Herein, we tested the hypothesis that DNA damage response (DDR) pathways are involved in resistance of OC patients to platinum chemotherapy. Selected DDR signals were evaluated in two human ovarian carcinoma cell lines, one sensitive (A2780) and one resistant (A2780/C30) to platinum treatment as well as in peripheral blood mononuclear cells (PBMCs) from OC patients, sensitive (n = 7) or resistant (n = 4) to subsequent chemotherapy. PBMCs from healthy volunteers (n = 9) were studied in parallel. DNA damage was evaluated by immunofluorescence γH2AX staining and comet assay. Higher levels of intrinsic DNA damage were found in A2780 than in A2780/C30 cells. Moreover, the intrinsic DNA damage levels were significantly higher in OC patients relative to healthy volunteers, as well as in platinum-sensitive patients relative to platinum-resistant ones (all P<0.05). Following carboplatin treatment, A2780 cells showed lower DNA repair efficiency than A2780/C30 cells. Also, following carboplatin treatment of PBMCs ex vivo, the DNA repair efficiency was significantly higher in healthy volunteers than in platinum-resistant patients and lowest in platinum-sensitive ones (t1/2 for loss of γH2AX foci: 2.7±0.5h, 8.8±1.9h and 15.4±3.2h, respectively; using comet assay, t1/2 of platinum-induced damage repair: 4.8±1.4h, 12.9±1.9h and 21.4±2.6h, respectively; all P<0.03). Additionally, the carboplatin-induced apoptosis rate was higher in A2780 than in A2780/C30 cells. In PBMCs, apoptosis rates were inversely correlated with DNA repair efficiencies of these cells, being significantly higher in platinum-sensitive than in platinum-resistant patients and lowest in healthy volunteers (all P<0.05). We conclude that perturbations of DNA repair pathways as measured in PBMCs from OC patients correlate with the drug sensitivity of these cells and reflect the individualized response to platinum-based chemotherapy.
authors: Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 11635 Athens, Greece; Department of Clinical Therapeutics, Athens University Medical School, 11528 Athens, Greece.
authors: Dimitra T
authors: DT
authors: Stefanou
authors: Department of Clinical Therapeutics, Athens University Medical School, 11528 Athens, Greece.
authors: Aristotelis
authors: A
authors: Bamias
authors: Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 11635 Athens, Greece; Genetic and Epigenetic Alterations of Genomes, de Duve Institute, Catholic University of Louvain, Brussels, 1200, Belgium.
authors: Hara
authors: H
authors: Episkopou
authors: Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 11635 Athens, Greece.
authors: Soterios A
authors: SA
authors: Kyrtopoulos
authors: Department of Clinical Therapeutics, Athens University Medical School, 11528 Athens, Greece.
authors: Maria
authors: M
authors: Likka
authors: Second Department of Obstetrics & Gynaecology, Athens University Medical School, 11528 Athens, Greece.
authors: Theodore
authors: T
authors: Kalampokas
authors: Second Department of Obstetrics & Gynaecology, Athens University Medical School, 11528 Athens, Greece.
authors: Stylianos
authors: S
authors: Photiou
authors: Department of Clinical Therapeutics, Athens University Medical School, 11528 Athens, Greece.
authors: Nikos
authors: N
authors: Gavalas
authors: First Department of Propedeutic Medicine, Athens University Medical School, 11527 Athens, Greece.
authors: Petros P
authors: PP
authors: Sfikakis
authors: Department of Clinical Therapeutics, Athens University Medical School, 11528 Athens, Greece.
authors: Meletios A
authors: MA
authors: Dimopoulos
authors: Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 11635 Athens, Greece.
authors: Vassilis L
authors: VL
authors: Souliotis
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects*; D016190:Carboplatin / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D018572:Disease-Free Survival; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000401:mortality; D010984:Platinum / Q000008:administration & dosage; D015996:Survival Rate
chemical_list: D000970:Antineoplastic Agents; D010984:Platinum; D016190:Carboplatin