The chemotherapy of solid tumours is hampered by two major obstacles: (1) the lack of selectivity of the current drugs and (2) the reduced sensitivity to tumour drugs. Recent advances in cancer biology have led to the identification of novel molecular targets responsible for aggressive proliferation, drug resistance and invasiveness. Targeting one such factor, epidermal growth factor receptor (EGFR), has proven an effective strategy to block the progression of solid tumours. However, the potency of the current clinical drugs directed at EGFR is mitigated by their reversible cytostatic activity and reduced cytotoxicity. Here we describe the design and synthesis of a new class of agents termed "cascade release combi-molecule" (I-TZ), "programmed" to hammer the receptor by releasing multiple bioactive metabolites (I-TZ', I-TZ") in a step-wise fashion and a reactive DNA damaging species (TZ), with the purpose of promoting sustained inhibition of EGFR tyrosine kinase (TK) and drug-induced cytotoxicity. This thesis describes the synthesis of one such molecule, RB24 (I-TZ), and demonstrates that it was capable of being hydrolyzed to its various sub-components with an overall half-life of 42 min under physiological conditions. The I-TZ induced sustained inhibition of the EGFR TK and strong antiproliferative activity in human solid tumour cells. It also inflicted higher levels of DNA damage to cancer cells transfected with the EGFR or HER2 gene. This selectivity was based on a novel mechanism of targeting described as a bystander effect, whereby following distribution of the I-TZ in the perinuclear region, the alkylating species (TZ) was subsequently released towards the nucleus. The I-TZ was significantly more potent than its clinical counterpart, TemodaI(TM). Further investigation of the mechanism underlying its superior potency show that blockade of EGFR-mediated signaling led to down-regulation of: (1) MAPK mitogenic signaling, (2) the BER protein, XRCC1 and (3) anti-apoptotic signaling mediated by Bad. Further down-regulation of XRCCI, with a MEK1 inhibitor, led to the discovery of a significant synergistic antiproliferative effect and a novel formula to further enhance the potency of the I-TZ in refractory tumours. Furthermore, the in vivo activity of the cascade release principle was proven in a prostate cancer xenograft study using a more water-soluble analogue of RB24. Thus, we have developed a novel model for the therapy of growth factor receptor-expressing tumours from the design and synthesis of the probe drugs, to the elucidation of their mechanism of action and the demonstration of the in vivo efficacy of the proposed strategy.

Thesis (Ph.D.)--University of California, San Francisco, 2007. / Source: Dissertation Abstracts International, Volume: 68-04, Section: B, page: 2270. Adviser: Matthias Hebrok.

Thesis (Ph.D.)--University of California, San Francisco, 2010. / Source: Dissertation Abstracts International, Volume: 71-02, Section: B, page: . Adviser: Xin Chen.

Oncolytic virotherapy (OV) is an innovative alternative to conventional cancer therapies based on the concept of selecting or engineering viruses to preferentially replicate in and kill tumor cells by exploiting their genetic defects. Intra-tumoural innate immunity plays a significant role in blocking the effective therapeutic spread of OV. Histone deacetylase inhibitors (HDIs) are known to blunt cellular anti-viral response. This research demonstrates that HDIs enhance the sensitivity of various cancer cell lines to the replication and spread of three different OV platforms---vesicular stomatitis virus (VSV), semliki forest virus (SFV) and vaccinia. The increased oncolytic activity of VSV correlated with a dampening of cellular interferon responses and augmentation of virus replication. Enhancement of virus replication post HDI treatment was also observed in multiple primary human tumor explants as well as in tumor bearing in vivo models. These results illustrate the general utility of HDIs as chemical switches to regulate cellular innate antiviral responses and to provide controlled growth of therapeutic viruses within malignancies.

Background. Colorectal cancer is the second leading cause of death from cancer in Canada. Many studies have examined associations between GSTM1, GSTT1, and GSTP1 polymorphisms and colorectal cancer but with conflicting results. The objective of this study was to examine the totality of evidence for association between these polymorphisms and risk for colorectal cancer or adenoma. Methods. A systematic review, meta- and pooled analysis were conducted. Results. The meta- and pooled analysis suggest weak significant associations between GSTM1 (ORpooled=1.11; 95%CI: 1.02,1.23), GSTT1 (ORpooled=1.22; 95%CI: 1.10,1.35), and with presence of null variants of each and colorectal cancer, but with heterogeneity between studies. No association between GSTP1 and colorectal cancer, or between any of the polymorphisms and colorectal adenoma, was observed. Significant multiplicative GST gene-gene interactions or gene-environment (smoking) interaction effects were not observed. Conclusion. Evidence to date shows weak associations between GSTM1 and GSTT1 and colorectal cancer.

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.)