title: Effects of oral contraceptives or a gonadotropin-releasing hormone agonist on ovarian carcinogenesis in genetically engineered mice.
abstract: Although epidemiologic evidence for the ability of combined oral contraception (OC) to reduce the risk of ovarian cancer (OvCa) is convincing, the biological mechanisms underlying this effect are largely unknown. We conducted the present study to determine if OC also influences ovarian carcinogenesis in a genetic mouse model and, if so, to investigate the mechanism underlying the protective effect. LSL-K-ras(G12D/+)Pten(loxP/loxP) mice were treated with ethinyl estradiol plus norethindrone, contraceptive hormones commonly used in combined OC, or norethindrone alone, or a gonadotropin-releasing hormone agonist. The combined OC had a 29% reduction in mean total tumor weight compared with placebo (epithelial tumor weight, -80%). Norethindrone alone reduced mean total tumor weight by 42% (epithelial tumor weight, -46%), and the gonadotropin-releasing hormone agonist increased mean total tumor weight by 71% (epithelial tumor weight, +150%). Large variations in tumor size affected the P values for these changes, which were not statistically significant. Nonetheless, the OC reductions are consistent with the epidemiologic data indicating a protective effect of OC. Matrix metalloproteinase-2 activity was decreased in association with OC, indicating that OC may affect ovarian carcinogenesis by decreasing proteolytic activity, an important early event in the pathogenesis of OvCa. In contrast, OC increased invasion in a K-ras/Pten OvCa cell line established from the mouse tumors, suggesting that OC hormones, particularly estrogen, may have a detrimental effect after the disease process is under way. Our study results support further investigation of OC effects and mechanisms for OvCa prevention.
authors.affiliation: Department of Obstetrics and Gynecology-Center forIntegrative Science, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Iris L
authors.initials: IL
authors.lastname: Romero
authors.forename: Ilyssa O
authors.initials: IO
authors.lastname: Gordon
authors.forename: Sujatha
authors.initials: S
authors.lastname: Jagadeeswaran
authors.forename: Keeley L
authors.initials: KL
authors.lastname: Mui
authors.forename: Woo Seok
authors.initials: WS
authors.lastname: Lee
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Dinulescu
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Krausz
authors.forename: Helen H
authors.initials: HH
authors.lastname: Kim
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Gilliam
authors.forename: Ernst
authors.initials: E
authors.lastname: Lengyel
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D003280:Contraceptives, Oral, Synthetic / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004967:Estrogens / Q000008:administration & dosage; D004997:Ethinyl Estradiol / Q000008:administration & dosage*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists*; D006062:Gonadotropins / Q000378:metabolism; D007124:Immunoenzyme Techniques; D019426:Integrases / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009361:Neoplasm Invasiveness; D009640:Norethindrone / Q000008:administration & dosage*; D010051:Ovarian Neoplasms / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D051059:PTEN Phosphohydrolase / Q000502:physiology; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D003280:Contraceptives, Oral, Synthetic; D004967:Estrogens; D006062:Gonadotropins; D007987:Gonadotropin-Releasing Hormone; D004997:Ethinyl Estradiol; C045073:Cre recombinase; D019426:Integrases; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse; D020778:Matrix Metalloproteinase 2; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras); D009640:Norethindrone