Ovarian cancer

Ovarian cancer is the leading cause of death from gynaecological cancers in women in Australia. Reproductive factors related to lifetime oestrogen exposure and obesity are linked to increasing risk of ovarian cancer and the typical Western diet, which is low in plant-based foods and high in red meat, has been implicated in raising ovarian cancer risk for which the use of herbal therapies is common in treating women with ovarian cancer, though few women consult a health practitioner for advice on usage and indications.

In vitro spheroids and metastatic epithelial ovarian cancer

This thesis investigated the role of cellular aggregation in the spread of epithelial ovarian cancer. Cell aggregation was studied in vitro in order to identify markers of disease progression and cell-cell adhesion. Proteomics was then used to identify additional proteins associated with cell aggregation and survival.

Multicellular spheroids in ovarian cancer metastases: Biology and pathology

Epithelial ovarian cancer (EOC) has a relatively high mortality rate (~55%). One of the presiding causes is that the current chemotherapeutic regimes are unable to achieve sustained remission, despite frequently producing a positive response at first treatment. One of the reasons that EOC is difficult to treat is that the mechanism of dissemination is unusual. EOC dissemination characteristically involves local invasion of pelvic and abdominal organs. Unlike many epithelial cancers, initial dissemination rarely requires the vasculature, although the vasculature is often implicated in the advanced stages of disease. Recently, it has become apparent that aggregates of malignant cells (spheroids) contained within malignant ascites represent a significant impediment to efficacious treatment of late stage EOC. In vivo, spheroids are present in the malignant ascites of EOC patients, while in vitro cultured spheroids are capable of tumorgenesis in vivo and display a reduced response to chemotherapeutic drugs when compared to monolayers. A major problem associated with the current generation of chemotherapy agents is that they do not address the anchorage and vascular-independent growth conditions associated with a 3-dimensional structure that has formed and/or grown in suspension. Thus, spheroid formation may represent a key component of platinum/taxanesensitive recurrence. If this is correct, a better understanding of spheroid biology may contribute to the identification of new treatment opportunities for the sustained treatment of metastatic EOC. This review article outlines the key biological features of spheroids, specifically discussing their role in EOC dissemination and chemo-response as well as providing insights into spheroid functionality.

High prevalence of symptoms associated with ovarian cancer among Australian women

Background: Symptoms associated with ovarian cancer are often vague and non-specific, such as abdominal bloating and pain. Presently, nothing is known about the prevalence of these symptoms among women in the community.
Aims: To identify the prevalence and correlates of symptoms associated with ovarian cancer in a nationally representative sample of Australian women.
Methods: Women answered questions about symptoms associated with ovarian cancer via computer-assisted telephone interviews. Binomial regression was used to assess the association between reporting symptoms, demographic characteristics and sexual problems.
Results: Data on 2235 women aged 18–70 who had not had an oophorectomy or hysterectomy were analysed.
Prevalences of symptoms were abdominal bloating 52%, abdominal pain 37%, increased abdominal size 30%, pelvic pain 29%, feeling full quickly 18% and unable to eat normally 15%. One-third of women (32%) reported three or more symptoms, 2% reported all six and 32% of women reported none. Severe symptoms were generally reported by <10% of women reporting symptoms, and symptoms usually persisted for 5 days or less a month. Older women were less likely to report symptoms, as were women who had been pregnant. There was an association between symptoms and sexual difficulties whereby women who reported multiple ovarian cancer symptoms were more likely to report sexual problems.
Conclusions: There is a high prevalence of ovarian cancer symptoms in the Australian community. Because of this, awareness campaigns will likely impact a large number of women who do not have ovarian cancer.

Aberrant cytokine signaling in ovarian cancer

The studies described in this thesis suggest that IL-6R family members have the potential to significantly impact on ovarian cancer progression. These results suggest that assessment of IL-6R family expression represents a potential prognostic tool in determining appropriate therapy for ovarian cancer patients.

Granulocyte colony-stimulating factor receptor signalling via Janus kinase 2/signal transducer and activator of transcription 3 in ovarian cancer

Ovarian cancer remains a major cause of cancer mortality in women, with only limited understanding of disease aetiology at the molecular level. Granulocyte colony-stimulating factor (G-CSF) is a key regulator of both normal and emergency haematopoiesis, and is used clinically to aid haematopoietic recovery following ablative therapies for a variety of solid tumours including ovarian cancer.

Symptoms of posttraumatic stress in Australian women with ovarian cancer

The aim of the study was to assess the prevalence and nature of symptoms of posttraumatic stress disorder (PTSD) in women with ovarian cancer. A further aim was to examine the demographic, medical and psychosocial factors associated with PTSD symptoms.

Posttraumatic reactions in women with ovarian cancer

The thesis examined the experience of posttraumatic stress symptoms and posttraumatic growth in women with ovarian cancer. Adaptive coping styles were found to be associated with increased growth and fewer symptom of PTSD. Higher levels of psychological distress and social disconnectedness were associated with increased PTSD symptoms and less growth.

Alisertib, an Aurora kinase A inhibitor, induces apoptosis and autophagy but inhibits epithelial to mesenchymal transition in human epithelial ovarian cancer cells.

Ovarian cancer is a leading killer of women, and no cure for advanced ovarian cancer is available. Alisertib (ALS), a selective Aurora kinase A (AURKA) inhibitor, has shown potent anticancer effects, and is under clinical investigation for the treatment of advanced solid tumor and hematologic malignancies. However, the role of ALS in the treatment of ovarian cancer remains unclear. This study investigated the effects of ALS on cell growth, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT), and the underlying mechanisms in human epithelial ovarian cancer SKOV3 and OVCAR4 cells. Our docking study showed that ALS, MLN8054, and VX-680 preferentially bound to AURKA over AURKB via hydrogen bond formation, charge interaction, and π-π stacking. ALS had potent growth-inhibitory, proapoptotic, proautophagic, and EMT-inhibitory effects on SKOV3 and OVCAR4 cells. ALS arrested SKOV3 and OVCAR4 cells in G2/M phase and induced mitochondria-mediated apoptosis and autophagy in both SKOV3 and OVCAR4 cell lines in a concentration-dependent manner. ALS suppressed phosphatidylinositol 3-kinase/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase pathways but activated 5'-AMP-dependent kinase, as indicated by their altered phosphorylation, contributing to the proautophagic activity of ALS. Modulation of autophagy altered basal and ALS-induced apoptosis in SKOV3 and OVCAR4 cells. Further, ALS suppressed the EMT-like phenotype in both cell lines by restoring the balance between E-cadherin and N-cadherin. ALS downregulated sirtuin 1 and pre-B cell colony enhancing factor (PBEF/visfatin) expression levels and inhibited phosphorylation of AURKA in both cell lines. These findings indicate that ALS blocks the cell cycle by G2/M phase arrest and promotes cellular apoptosis and autophagy, but inhibits EMT via phosphatidylinositol 3-kinase/Akt/mTOR-mediated and sirtuin 1-mediated pathways in human epithelial ovarian cancer cells. Further studies are warranted to validate the efficacy and safety of ALS in the treatment of ovarian cancer.

Targeting epithelial-mesenchymal transition and cancer stem cells for chemoresistant ovarian cancer

Chemoresistance is the main challenge for the recurrent ovarian cancer therapy and responsible for treatment failure and unfavorable clinical outcome. Understanding mechanisms of chemoresistance in ovarian cancer would help to predict disease progression, develop new therapies and personalize systemic therapy. In the last decade, accumulating evidence demonstrates that epithelial-mesenchymal transition and cancer stem cells play important roles in ovarian cancer chemoresistance and metastasis. Treatment of epithelial-mesenchymal transition and cancer stem cells holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. In this review, we focus on the role of epithelial-mesenchymal transition and cancer stem cells in ovarian cancer chemoresistance and explore the therapeutic implications for developing epithelial-mesenchymal transition and cancer stem cells associated therapies for future ovarian cancer treatment.

α2β1 integrin affects metastatic potential of ovarian carcinoma spheroids by supporting disaggregation and proteolysis

Background: Ovarian cancer is characterized by a wide-spread intra-abdominal metastases which represents a major clinical hurdle in the prognosis and management of the disease. A significant proportion of ovarian cancer cells in peritoneal ascites exist as multicellular aggregates or spheroids. We hypothesize that these cellular aggregates or spheroids are invasive with the capacity to survive and implant on the peritoneal surface. This study was designed to elucidate early inherent mechanism(s) of spheroid survival, growth and disaggregation required for peritoneal metastases.

Methods: In this study, we determined the growth pattern and adhesive capacity of ovarian cancer cell lines (HEY and OVHS1) grown as spheroids, using the well established liquid overlay technique, and compared them to a normal ovarian cell line (IOSE29) and cancer cells grown as a monolayer. The proteolytic capacity of these spheroids was compared with cells grown as a monolayer using a gelatin zymography assay to analyze secreted MMP-2/9 in conditioned serum-free medium. The disaggregation of cancer cell line spheroids was determined on extracellular matrices (ECM) such as laminin (LM), fibronectin (FN) and collagen (CI) and the expression of α2, α3, αv, α6 and β1 interin was determined by flow cytometric analysis. Neutralizing antibodies against α2, β1 subunits and α2β1 integrin was used to inhibit disaggregation as well as activation of MMPs in spheroids.

Results: We demonstrate that ovarian cancer cell lines grown as spheroids can sustain growth for 10 days while the normal ovarian cell line failed to grow beyond 2 days. Compared to cells grown as a monolayer, cancer cells grown as spheroids demonstrated no change in adhesion for up to 4 days, while IOSE29 cells had a 2–4-fold loss of adhesion within 2 days. Cancer cell spheroids disaggregated on extracellular matrices (ECM) and demonstrated enhanced expression of secreted pro-MMP2 as well as activated MMP2/MMP9 with no such activation of MMP's observed in monolayer cells. Flow cytometric analysis demonstrated enhanced expression of α2 and diminution of α6 integrin subunits in spheroids
versus monolayer cells. No change in the expression of α3, αv and β1 subunits was evident. Conversely, except for αv integrin, a 1.5–7.5-fold decrease in α2, α3, α6 and β1 integrin subunit expression was observed in IOSE29 cells within 2 days. Neutralizing antibodies against α2, β1 subunits and α2β1 integrin inhibited disaggregation as well as activation of
MMPs in spheroids.

Conclusion: Our results suggest that enhanced expression of α2β1 integrin may influence spheroid disaggregation and
proteolysis responsible for the peritoneal dissemination of ovarian carcinoma. This may indicate a new therapeutic target
for the suppression of the peritoneal metastasis associated with advanced ovarian carcinomas.

Epidermal growth factor-induced ovarian carcinoma cell migration is associated with JAK2/STAT3 signals and changes in the abundance and localization of α6β1 integrin

Peritoneal dissemination of ovarian carcinoma is mediated by epithelial–mesenchymal interconversions leading to the disruption of cell–cell contact and modulation of cell–extracellular matrix (ECM) interactions. The present study was designed to evaluate the effects of epidermal growth factor (EGF) as a modulator of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) signalling and changes in integrin expression during the process similar to EMT. A fibroblastic morphology with reduced intercellular cell contacts and increased cell motility was observed in ovarian cancer cell lines in response to EGF and was concomitant with the up regulation of EMT-associated N-cadherin and vimentin expression. These changes were accompanied by an increase in α2, α6 and β1 integrin subunits and activation of JAK2 and STAT3 signalling which was suppressed by a specific JAK2 inhibitor. Consistent with the suppression of STAT3 activity, N-cadherin and vimentin expression were abrogated and was coherent with the loss of cell motility and the expression of α6 and β1 integrin subunits. Neutralizing antibodies against α6 and β1 subunits inhibited cancer cell migration. A strong correlation between the expression of N-cadherin, vimentin and JAK2/STAT3 levels were detected in high-grade ovarian tumors and was consistent with the previously reported enhanced expression of α6 integrin subunit in advanced tumors [Ahmed N, Riley C, Oliva K, Rice G, Quinn M. Ascites induces modulation of α6β1 integrin and urokinase plasminogen activator receptor expression and associated functions in ovarian carcinoma. British Journal of Cancer 2005;92:1475–85]. Our data incorporating the clinical samples and the cancer cell lines is the first to demonstrate that JAK2/STAT3 pathway may be one of the downstream events in EMT-like process and α6β1 integrin-mediated signalling in ovarian carcinomas.