Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Ovarian cancer results from the dysregulation, in normal ovarian epithelial cells, of genes responsible for the control of critical biological processes. Since their discovery 20 years ago, microRNAs have increasingly been implicated in that dysregulation due to their role mediating gene expression; changes in microRNA expression levels in cancer have been linked with tumor growth, proliferation and metastasis. Their imputed involvement in cancer has led to the possibility of their use as biomarkers and to their potential clinical use. Using mRNA and microRNA microarray analysis to compare human gene expression in normal ovarian surface epithelial (OSE) cells and epithelial ovarian cancer (EOC) cells, we explored the interactions between microRNAs and genes. First, we validated in silico predictions of microRNA targets by comparing them with in vitro evidence after exogenous microRNA transfection. We found that pairs of microRNAs with identical 7-nt (nucleotide) seed regions shared 88% of their predicted targets and 55% of their in vitro targets, confirming the importance of the seed as a targeting mechanism. But more importantly, we found that even a single nucleotide change in the seed region can result in a significant shift in the set of targeted genes, implying strong functional conservation of the seeds and their corresponding binding sites. Next, we discovered a 3-element network motif which explains the upregulation of nearly 800 genes in ovarian cancer which, as predicted microRNA targets, might be expected to be down- regulated. This model shows that, under certain circumstances, repressor genes which are down- regulated in cancer can apparently override the repressive effects of microRNAs, resulting in the upregulation of predicted microRNA targets. Finally, we developed a phenomenological network model, based on the Pearson correlation of microarray gene expression data, to identify subnetworks dysregulated in cell cycle and apoptosis. While our methodology reported many genes previously associated with ovarian cancer, it significantly suggested potentially oncogenic genes for further investigation. This network model can easily be extended to identify dysregulated genes in other cancers.

Women with advanced ovarian cancer generally have a poor prognosis but there is significant variability in survival despite similar disease characteristics and treatment regimens. The aim of this study was to determine whether psychosocial factors predict survival in women with ovarian cancer, controlling for potential confounders.

Menopause is associated with disorders such as osteoporosis and ovarian cancer. It is unclear whether the postmenopausal ovary retains steroidogenic capacity and how it can impact the development of these disorders. The present studies used the VCD-treated follicle-depleted mouse model of menopause to test the hypothesis that residual ovarian tissue retains steroidogenic capacity following ovarian failure and, thus, affects the development of these disorders. Microarray technology was used to evaluate gene expression in residual ovarian tissue of follicle-depleted mice compared to that in ovaries from cycling animals. Among the genes identified were those encoding proteins for synthesis of androgens. Steroidogenic capacity of residual ovarian tissue was further evaluated by determining the expression of genes and proteins involved in ovarian steroidogenesis, and by measuring levels of circulating and rostenedione and gonadotropins. Follicle-depleted ovaries were enriched in mRNAs for androgenic enzymes, receptors involved in the internalization of cholesterol, and luteinizing hormone receptor. Increased circulating levels of FSH and LH and detectable and rostenedione were measured throughout the study. Protein for 3β-hydroxysteroid dehydrogenase, 17α- hydroxylase/17,20-lyase and luteinizing hormone receptor was detected in follicledepleted ovaries by Western blot analysis and localized by immunofluorescence staining. The contribution of retaining residual ovarian tissue to accelerated bone loss following ovarian failure was evaluated by comparing bone mineral density from young and aged VCD-treated mice to that in age-matched ovariectomized (OVX) animals. Retaining residual ovarian tissue resulted in protection against accelerated bone loss in young but not aged VCD-treated mice. Whether residual ovarian tissue is more susceptible to development of ovarian neoplasms compared to ovaries from cycling animals was addressed by combining the VCD-treated mouse with the DMBA model of ovarian carcinogenesis. VCD-treated follicle-depleted mice that received DMBA developed Sertoli-Leydig cell tumors while no tumors were observed in cycling animals. Residual ovarian tissue following ovarian failure appears to have a protective effect against loss of bone integrity, but a detrimental effect on development of ovarian neoplasms. Findings from these studies: provided evidence of a physiological role for residual ovarian tissue following ovarian failure, and furthered the use of the VCD-treated mouse as a relevant model for menopause and associated disorders.

Kidney disease is a major complication of diabetes and accounts for one-third of all diabetes-related deaths. Estrogen is considered protective against cardiovascular and non-diabetic renal disease, however it is unclear if this protection extends to diabetes and diabetic kidney disease.To address these questions, we have used a new model of menopause in which repeated daily injections of 4-vinylcyclohexene (VCD) induces gradual ovarian failure in mice. Unlike with ovariectomy, the VCD model preserves the gradual transition into ovarian failure (OF) (modeling perimenopause). Also, following OF, the residual ovarian tissue is retained and secretes androgens, similar to the androgen production by postmenopausal human ovaries.The VCD model of menopause was combined with the streptozotocin (STZ) model of type 1 diabetes, and the development of diabetes and diabetic kidney damage were studied over the subsequent 6 weeks. We observed that blood glucose levels are higher in post-OF diabetic mice compared to cycling diabetic and peri-OF diabetic mice. Renal cell proliferation, an early marker of kidney damage, is increased in post-OF diabetic mice compared to cycling diabetic mice, as measured by expression of proliferating cell nuclear antigen. We also demonstrate that expression of α-smooth muscle actin is increased in post-OF diabetic mice compared to cycling diabetic mice. Five weeks after STZ injection, post-OF diabetic mice had higher rates of urine albumin excretion than cycling diabetic mice.Using real-time PCR, we identified changes in expression between post-OF diabetic and cycling diabetic mice of genes which have previously been associated with diabetic kidney damage. We also show that some of these changes occur in peri-OF diabetic mice as well. Using microarray, we identified 119 new genes which are regulated by the combination of ovarian failure and diabetes in the mouse kidney.These data support our hypothesis that the changes in hormones which occur during the transition into ovarian failure exacerbate the development and progression of diabetic kidney damage in mice. These data also highlight the utility and importance of the VCD model of menopause in the study of diabetic kidney damage.

Ovarian cancer is the leading cause of gynecologic cancer death among women in the United States, claiming the lives of more than 15,000 women each year. Women who receive this diagnosis must make rapid, critical medical decisions that impact survival and quality of life. Two studies were conducted to obtain pilot data related to the health preferences of ovarian cancer patients and their oncologists. Forty-one eligible patients and 34 eligible physicians participated in this study. Six hypothetical health states were developed based on possible outcomes of ovarian cancer treatment strategies. Participants were asked to rate these health states using a visual analog scale and the standard gamble chance board. A series of exploratory hypotheses were tested to obtain guidance for future research. Patients under surveillance had significantly lower preferences for all health states than patients receiving chemotherapy or physicians. Overall, patients were very consistent across health states with the level of risk they were willing to take, while physicians were significantly more likely to avoid risk when the treatment strategy presented involved improved treatment efficacy, even when associated with higher toxicity and poor emotional well being. These findings show the need for additional research and suggest that research in medical decision making must examine health choices made by patients separately, depending on their current treatment status, but not necessarily by current self-reported health status, time since diagnosis or by recurrent/non-recurrent disease.

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