Cyclooxygenase (COX) (PTGS) is the rate-limiting enzyme in the biosynthesis of prostaglandins. Two COX isoforms have been identified, COX-1 and COX-2, which show distinct cell-specific expression and regulation. Ovarian cancer is the most lethal gynecological malignancy and the © Humana Press Inc. 2008 Correspondence to: Dale Buchanan Hales, dbhale@uic.edu. HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript disease is poorly understood due to the lack of suitable animal models. The laying hen spontaneously develops epithelial ovarian cancer with few or no symptoms until the cancer has progresses to a late stage, similar to the human disease. The purpose of this study was to examine the relative expression and distribution of COX-1 and COX-2 in the ovaries of normal hens and in hens with ovarian cancer. The results demonstrate that COX-1 was localized to the granulosa cell layer and cortical interstitium, ovarian surface epithelium (OSE) and postovulatory follicle (POF) of the normal ovary. In ovarian cancer, COX-1 mRNA was significantly increased and COX-1 protein was broadly distributed throughout the tumor stroma. COX-2 protein was localized to the granulosa cell layer in the follicle and the ovarian stroma. COX-2 mRNA expression did not change as a function of age or in ovarian cancer. There was significantly higher expression of COX-1 mRNA in the first POF (POF-1) compared to POF-2 and POF-3. COX-2 mRNA expression was not significantly different among POFs. There was no difference in COX-1 or COX-2 mRNA in the OSE isolated from individual follicles in the follicular hierarchy. The results confirm previous findings of the high expression of COX-1 in ovarian tumors further supporting the laying hen as a model for ovarian cancer, and demonstrate for the first time the high expression of COX-1 in POF-1 which is the source of prostaglandins needed for oviposition.

Objective With the exception of the laying hen, no other animal model of spontaneous ovarian surface epithelial cancer replicates the human disease. Flaxseed is the richest vegetable source of omega-3 fatty acids, which are chemopreventative in breast cancer and may be important in other cancers. The objective of this study was to determine if a flaxseed enriched diet had a chemopreventative effect on ovarian cancer in the laying hen. Methods White leghorn hens were fed a 10% flaxseed enriched or standard diet for one year. The incidence and severity of ovarian cancer were determined by gross pathology and histology in the two groups. General health markers were also measured. Eggs were collected and analyzed by gas chromatography to determine omega-3 fatty acid levels. Results A significant reduction in late stage ovarian tumors was detected in the flaxseed fed hens. Incidence rates of ovarian cancer were not significantly different between the two groups. The results indicate that a flaxseed diet increases overall survival in the laying hen. Flaxseed fed hens’ eggs incorporated significantly more omega-3 fatty acids compared to control hens. Conclusions These findings show that 10% flaxseed supplementation for one year in the laying hen results in a significant reduction in the severity of ovarian cancer, but no change in the incidence of the disease. Hens fed flaxseed had overall better health and reduced mortality. These findings may provide the basis for a clinical trial that evaluates the efficacy of flaxseed as a chemosuppressant of ovarian cancer in women.

Objective-Epithelial ovarian carcinoma (EOC) is a leading cause of cancer deaths in women. Until recently, a significant lack of an appropriate animal model has hindered the discovery of early detection markers for ovarian cancer. The aging hen serves as an animal model because it spontaneously develops ovarian adenocarcinomas similar in histological appearance to the human disease. E-cadherin is an adherens protein that is down-regulated in many cancers, but has been shown to be up-regulated in primary human ovarian cancer. Our objective was to evaluate E-cadherin expression in the hen ovary and compare its expression to human ovarian cancer. Methods-WhiteLeghorn hens aged 185 weeks (cancerous and normal) were used for sample collection. A human ovarian tumor tissue array was used for comparison to the human disease. Ecadherin mRNA and protein expression were analyzed in cancerous and normal hen ovaries by immunohistochemistry (IHC), Western blot, and quantitative real-time PCR (qRT-PCR). Tissue fixed in neutral buffered formalin was used for IHC. Protein from tissue frozen in liquid nitrogen was analyzed by Western blot. RNA was extracted from tissue preserved in RNAlater and analyzed by qRT-PCR. The human ovarian tumor tissue array was used for IHC.Results-E-cadherin mRNA and protein expression were significantly increased in cancerous hen ovaries as compared to ovaries of normal hens by qRT-PCR and Western blot. Similar expression of E-cadherin was observed by IHC in both human and hen ovarian cancer tissues. Similar E-cadherin expression was also observed in primary ovarian tumor and peritoneal metastatic tissue from cancerous hens.Conclusions-Our findings suggest that the up-regulation of E-cadherin is an early defining event in ovarian cancer and may play a significant role in the initial development of the primary ovarian tumor. E-cadherin also appears to be important in the development of secondary tumors within the peritoneal cavity. Our data suggest that E-cadherin may prove to be an important target in the preventative treatment of metastatic ovarian cancer and further confirm that the laying hen is a good model for the study of human epithelial ovarian carcinoma.

Objectives-Ovarian carcinoma is the most lethal gynecological malignancy. The genetic and molecular mechanisms that cause it still remain largely unknown. CYP1B1 is a cytochrome P450 enzyme that catalyzes the conversion of estrogens to genotoxic catechol estrogens which may cause DNA mutations and initiate ovarian epithelial cancer. Our objectives were to evaluate CYP1B1 expression, distribution and localization in the hen ovary and to determine if there is an increased CYP1B1 expression associated with, and possibly involved in the initiation of ovarian cancer.Methods-Two groups of hens were used: 1. young (50 weeks of age; devoid of cancer) and 2. old (165 weeks of age; divided into two groups: age-matched normal and ovarian cancer). CYP1B1 mRNA and protein expression were analyzed in cancerous ovaries, ovaries of age-matched normal and/or young hens by quantitative real-time PCR (qRT-PCR), in situ hybridization (ISH) and immunohistochemistry (IHC). RNA was extracted from tissue preserved in RNAlater for qRT-PCR. Tissue frozen in liquid nitrogen was used for ISH. Tissue fixed in neutral buffered formalin was subjected to IHC.Results-Higher expression of CYP1B1 mRNA was observed in cancerous ovaries as compared to ovaries of young and age-matched normal hens by qRT-PCR. ISH and IHC confirmed that the expression of CYP1B1 was much higher in ovarian tumors compared to ovaries of age-matched normal hens. CYP1B1 mRNA and protein were distributed extensively throughout the carcinoma, while primarily localized to the granulosa layer surrounding the follicle in age-matched normal hens. IHC also showed nuclear localization of CYP1B1. Highly expressed CYP1B1 was found in POF-3 from young and age-matched normal hens as compared to POF-1 and POF-2 by qRT-PCR. No significant difference was found in the expression of CYP1B1 between the distal (site of rupture) and the proximal (site of attachment to the ovary) of POF-1 from young and age-matched normal hens. Publisher's Disclaimer: This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. Conclusions-High expression of CYP1B1 in the hen ovary is associated with ovarian cancer and our data suggest that CYP1B1 may play an important role in the initiation of ovarian cancer and may prove to be a target for intervention. Moreover, the results of this study further confirm that the laying hen is a good model to study human ovarian cancer.