<p> Treatment for prostate cancer patients who experience recurrent disease involves androgen deprivation therapy (ADT) as prostate tumors are primarily driven by activation of the androgen receptor (AR). However, most patients on this therapy relapse within a few years after which this treatment fails to extend survival and progresses to castration resistant prostate cancer (CRPC). Treatment for CRPC often involve inhibitors of the AR itself, however, patients on these treatments often fail as well. The main cause for the failure of many therapies is acquired resistance to treatment; therefore, there is an urgent need to better understand this resistance for improved disease management. Protein translation plays an important role in altering signaling pathways by modifying protein expression levels, and offer promising targets for preventing acquired resistance. mTOR (mechanistic target of rapamycin) is a key regulator of protein translation in humans, and multiple mTOR inhibitors have been developed over the years and used in many diseases as treatment, including prostate cancer. EIF4E is a key component of the translational mechanism in eukaryotic organisms and its phosphorylation has been implicated in resistance to several therapies in many cancer types. EIF4E is involved in both cap-dependent and &ndash;independent translation, however, mTOR regulates only cap-dependent translation. Here I demonstrate using my data from <i>in vitro</i> studies as well as human-derived tumor-xenograft models that phosphorylation of eIF4E at Ser209 plays a significant role in the resistance of prostate tumors to AR and mTOR inhibition, by changing the mechanism of protein translation from cap-dependent to cap-independent to maintain tumor cellular proliferation, growth and survival. In recent years, many clinical trials used combinations of mTOR and AR inhibitors in patients with CRPC who have failed first line therapy; many of these studies fail especially if they are conducted in patients who had been pre-treated with an AR inhibitor; whereas others partially succeed if they are used in untreated patients. The overall goal of my thesis is to study the role of eIF4E phosphorylation in the development of resistance to mTOR and AR inhibitors in prostate cancer. My data points to AR as a suppressor of eIF4E phosphorylation, therefore explaining why prior treatment with the AR inhibitor bicalutamide made patients resistant to a combination of bicalutamide with the mTOR inhibitor RAD001. Furthermore, our results show that the receptor tyrosine-protein kinase ErbB3 negatively regulates phosphorylation of eIF4E, and high levels of ErbB3 may be an indicative of tumors that would respond to the combination therapy. Taken together, our studies demonstrate the mechanisms by which prostate cancer acquires resistance to mTOR and AR inhibition and explain some of the responsible proteins and pathways that are involved in this process. We also indicate promising biomarkers for evaluation of therapy effectiveness with this combination in prostate cancer patients.</p><p>

Proliferation of atypical megakaryoblasts is a characteristic of megakaryoblastic leukemia. Cell lines established from patients with this disorder show presence of gelsolin but absence of scinderin expression, two filamentous actin severing proteins present in normal megakaryocytes and platelets. Vector-mediated expression of scinderin (pcDNA3-Sc) in the megakaryoblastic cell line MEG-01 induced a decrease in F-actin and gelsolin as evaluated by immunocytochemistry, image analysis and immunoblotting. This was accompanied by an increased Rac2 expression followed by activation of PAK/MEKK.SEK/JNK/c-jun, c-fos and the Raf/MEK/ERK transduction pathways. Transduction pathway activation was responsible for cell differentiation, polyploidization, maturation and apoptosis with release of platelet-like particles. Platelet-like particles expressed surface CD41 a antigen, had dense core vesicles, a high affinity serotonin transport and a circular array of microtubules. Treatment of platelet-like particles with thrombin induced aggregation and release of serotonin. Cell proliferation and the cells' ability to form tumours in nude mice were also inhibited by expression of scinderin. The lack of scinderin expression in megakaryoblastic leukemia cells seems to be responsible for their inability to enter into differentiation and maturation pathways characteristic of their normal counterparts.

Objectives. Data from one small randomized trial has suggested a benefit for high-dose chemotherapy/autologous hematopoietic progenitor cell transplantation (HDCT/AHPCT) as compared with conventional chemotherapy (CCT) in patients with metastatic breast cancer. However, the study was considered to have had some limitations based on methodology, analysis, and sample size. The present study sought to compare differences in outcome in patients with metastatic breast cancer undergoing HDCT/AHPCT as compared with historical controls undergoing CCT. The principal endpoints analyzed were overall survival and time to first failure after beginning chemotherapy. Secondary outcomes included an analysis of predictors of time to first recurrence of breast cancer, analyses of prognostic factors for overall survival at recurrence, of time to first failure from the time of beginning chemotherapy, and for survival after HDCT/AHPCT. Conclusions. The use of HDCT/AHPCT in metastatic breast cancer may confer advantages with respect to overall survival and time to first failure after beginning chemotherapy. These advantages appear to be independent of the effects of selection bias and variously cited prognostic factors. This benefit if confirmed in ongoing randomized trials will have to be considered in light of differences in cost and quality of life between the two therapeutic modalities. (Abstract shortened by UMI.)

In the present study, we have used cultures of established cell lines of cisplatin (CDDP)-sensitive human ovarian epithelial tumours (OV2008 and A2780-s) and their resistant variants (C13* and A2780-cp, respectively) to assess the role of Fas/FasL system in the chemo-responsiveness of ovarian cancer cells to CDDP. CDDP was effective in inducing the expression of cell-associated Fas and FasL, sFasL and apoptosis in a concentration and time-dependent fashion in both OV2008 and A2780-s cell lines. In contrast, while CDDP was effective in increasing cell-associated Fas protein content in C13*, it failed to upregulate FasL and sFasL and induce apoptosis, irrespective of concentration and duration of CDDP treatment. In the resistant A2780-cp cells, neither Fas nor FasL upregulation and apoptosis were evident in the presence of CDDP. Addition of concentrated spent media from OV2008 after CDDP on C13* cells demonstrates a low level of apoptotic activity which is partially blocked by a Fas antagonistic Ab. Activation of the Fas signaling pathway, by addition to the cultures an agonistic Fas mAb, was effective in inducing apoptosis in both OV2008 and C13*. A significant interaction between CDDP and Fas agonist mAb was observed in the apoptotic response in OV2008 and C13* when cultured in the presence of both agents. (Abstract shortened by UMI.)

Abstract not available.

Glioblastoma multiforme, a high grade malignant astrocytoma, is the most common and mortal intracranial tumor in adults. The median survival time for glioblastoma patients remains from 9--12 months despite aggressive treatment programs. These high-grade central nervous system tumors bear genetic and molecular aberrations that result in innate chemoresistance to commonly used chemotherapeutic agents. The main focus of this thesis is on exploring signaling events downstream of phosphoinositide 3-kinase (PI3-K) in glioblastoma multiforme in attempts to discover molecular targets that may be highly specific and thus less toxic therapeutic targets. The PI3-K pathway is constitutively activated in glioblastoma. The Protein Kinase C family of serine/threonine kinases is activated downstream of PI3-K. Our focus is placed on a member of the atypical protein kinase C subfamily called, atypical PKC iota. We finally began examining the role of atypical PKC iota and invasion in U87MG glioblastoma cells using scratch/wound assays. (Abstract shortened by UMI.)

Oxygen supports the life of all aerobic organisms and virtually every cell type is capable of sensing decreased tissue oxygenation, known as hypoxia. Hypoxic microenvironments have been detected within developing solid tumors as a result of insufficient host vascular delivery of oxygen and nutrients. Consequently, the formation of solid tumors requires the coordination of angiogenesis: the recruitment of blood vessels for the purpose of tumor vascularization. Furthermore, clinical and experimental evidence have demonstrated that hypoxic cells in solid tumors can limit the efficacy of standard anticancer therapeutics including radiotherapy and chemotherapy. Low oxygenation can also accelerate malignant progression and metastasis resulting in poorer prognosis irrespective of the chosen treatment regiment. It is the focus of our research to improve our understanding of the molecular events that support the development of tumor cell resistance to hypoxia as a tool for the discovery of effective therapeutics that can specifically and effectively target hypoxic tumors. Understanding exactly how tumor cells adapt to transient hypoxia could lead to the identification of novel therapeutic targets that in combination therapy with current anticancer treatments could help reduce the incidence of morbidity and mortality from cancer.

A decision whether to receive chemotherapy for stage IV non-small cell lung cancer (NSCLC) is one in which the benefits and risks of the treatment and the personal values of the patient must be considered. Objectives of the study were to develop and conduct a preliminary evaluation of a decision aid for patients making the decision about chemotherapy for stage IV NSCLC. In particular, this study: (1) evaluated the effect of the decision aid on the patient's comprehension of the treatment alternatives, benefits and risks; (2) evaluated the effect of the decision aid on the decisional conflict experienced by the patient; and (3) evaluated the decision aid's acceptability to patients and practitioners. The decision aid was developed by Valerie Fiset, Dr Annette O'Connor, Dr Bill Evans, Dr Jo Logan and Cathy DeGrasse. It includes information describing advanced lung cancer, its effects and what people may do to cope with those effects. As well, the decision aid describes supportive care, radiation therapy, and chemotherapy, discussing in detail the benefits and risks of chemotherapy. The last part of the decision aid is an exercise in values clarification, which helps the patient to think about what is most important to them in making the decision about chemotherapy. (Abstract shortened by UMI.)

Kaposi's sarcoma (KS) is a multifocal proliferative disorder that is commonly associated with individuals who suffer some degree of reduction in immune competence. Therapy for this disorder varies and is determined by the seriousness of KS disease in the patient as well as the patient's ability to tolerate the different treatments. A better understanding of how KS arises would allow investigators to tailor therapies that would be more specific to KS and less detrimental to the individual. In this work, cell lines were established from skin biopsies taken from KS lesions of individuals with AIDS. The KS1 cell line presented as a combination of adherent and non-adherent cells that proliferated aggressively without senescence. The KS4 cell line presented as the typical spindle cell population that proliferated aggressively, but eventually senesced. Both cell lines were positive for the presence of Factor VIII-related antigen (FVIII) and the production of IL-6 and basic Fibroblastic Growth Factor (bFGF). When the association with Human Herpesvirus 8 (HHV8) was assessed, the virus proved undetectable in both cell lines. The response of the KS cell lines to Doxorubicin, Etoposide, and ALX40-4C was assessed. (Abstract shortened by UMI.)

Our laboratory has been interested in factors in the tumour microenvironment that may contribute to mutagenesis, and thus lead to tumour progression. The well documented relationship between chronic inflammatory states and cancer implicates inflammatory cells, such as macrophages and neutrophils, and their products as having a role in carcinogenesis. Using the MN-11 system, an in vitro/in vivo murine tumour model developed in our laboratory, the mutagenicity of neutrophils and one of their products, reactive nitrogen species, was studied. To further investigate the mechanism of the observed mutagenicity of nitric oxide donors on MN-11 cells, cellular glutathione levels of cells treated with glyceryl trinitrate (GTN) and sodium nitroprusside (SNP) were manipulated. Reactive nitrogen species, such as nitric oxide, are part of the microbicidal armament of neutrophils. Neutrophils have been implicated as a possible link between chronic inflammation and cancer, and are the most abundant inflammatory cell type observed in MN-11 tumours. Thus, the role that neutrophils have in causing mutations was investigated. (Abstract shortened by UMI.)