Tamoxifen is an effective anti-estrogen for treatment of women with hormonedependent breast cancer but acquired drug resistance limits its therapeutic benefit. We have previously reported that expression of active Akt3 in MCF-7 breast cancer cells results in estrogen-independent tumors that are actually stimulated to grow after tamoxifen treatment. We hypothesize that this tamoxifen resistance may be attributed to binding of different co-regulator proteins and/or different binding affinity of these proteins to the estrogen receptor in M CF-7 cells overexpressing active Akt3 as compared to parental MCF-7 cells. We have immuno-precipitated the estrogen receptor along with bound co-regulator proteins in both cells lines after tamoxifen, estradiol, or vehicle treatment. After 2-D gel electrophoresis separation of these immuno-precipitated proteins and comparing them using PDQuest 2-D analysis software, we identified protein spots that were statistically different under the treatment conditions between the two cell lines. The isolated protein spots were subjected to MALDI-TOF mass spectrometry. By searching protein databases through the MASCOT website for protein identification, we have identified estrogen receptor co-regulator proteins that may play a potential role in tamoxifen resistance. Current studies are focused on addressing the role of differential protein binding as a possible mechanism of tamoxifen resistance in Akt3 over-expressing breast cancer cells.

In the present study, two different drugs were used to induce a Parkinson-like condition. The first drug was the centrally acting cholinergic agonist oxotremorine (OXTM) which readily induces tremor and rigidity in mice (54). This tremor has been reported to be antagonized by dopamine agonists such as L-dopa and apomorphine (50,54,55) as well as by anticholinergic drugs such as scopolamine (46) . The other drug used was reserpine which interferes with the neuronal storage of dopamine and results in its depletion in the brain (56). Reserpine induces tremor, rigidity, blepharoptosis (a drooping of the eyelids), and catalepsy (48,57-59). The catalepsy is readily reversed by the administration of L—dopa (48,60-62). Using these two models of Parkinson's disease, selected narcotic antagonists have been tested to determine if they could potentiate dopaminergic influences and restore the normal balances of acetylcholine and dopamine in the corpus striatum.

Tumour cell dissemination is a major issue with the treatment of cancer, thus new therapeutic strategies which can control this process are needed. Antagonism of integrins highly expressed in tumours is one potential strategy. The integrins are transmembrane glycoprotein adhesive receptors. Two of the integrins, αVβ3 and αIIbβ3, are highly expressed in a number of tumours and induce bi-directional signalling through their interaction with extracellular matrix proteins, and growth factor receptors. Through this signalling they play an important role in a number of cellular processes that are involved in tumour dissemination such as tumour growth, migration, invasion, metastasis and angiogenesis. Dual αIIbβ3 and αVβ3 integrin antagonism will have a direct effect on β3-expressing tumour cells that leads to the inhibition of cell migration and dissemination. Furthermore, through targeting tumour cell interaction with endothelial cells and platelets, this will also lead to inhibition of angiogenesis and metastasis. The aim of this project was to characterise the expression of αVβ3 and αIIbβ3 integrin in a panel of tumour cell lines and in human tumour xenograft samples, and to develop and utilise cell-based models to investigate potential novel β3 antagonists. The expression of αV and β3 subunits was detected in xenograft tissue using immunoblotting techniques. A panel of cell lines of different tumour types including melanoma, prostate, breast, colon and non small cell lung carcinoma was then characterised for αVβ3 and αIIbβ3 integrin expression using immunoblotting and immunocytochemistry. Melanoma cell lines demonstrated the strongest αVβ3 expression. No αIIbβ3 integrin expression was seen in any of the cell lines evaluated. A selection of cell lines with varying αVβ3 expression were then used to develop a functional test for cell migration, the scratch wound healing assay. Migration of tumour cells that expressed αVβ3 integrin was inhibited by the known β3 antagonists, cRGDfV peptide and LM609 antibody. A panel of 12 potential novel β3 integrin antagonists was screened for cytotoxicity and activity in the validated scratch assay. ICT9055 was the most effective antagonist in inhibition of M14 cell migration as determined by the scratch assay, with an IC50 of < 0.1 µM. Therefore the work presented in this thesis has established models and tools for evaluating potential novel β3 integrin antagonists, and identified a promising molecule to progress for further preclinical evaluation. / Public Authority for Applied Education and Training (PAAET)

Methylene tetrahydrofolate reductase has been purified 1000-fold from porcine kidney and 400-fold from mouse L1210-induced tumor tissue by classical methods. The enzyme preparations have been demonstrated to be essentially free of contaminating methionine synthetase and serine transhydroxymethylase activity. Studies of the kinetic properties of the kidney and tumor enzymes, with respect to the reverse reaction using N5-methyl tetrahydrofolate as the variable substrate, have indicated Km values of 2.0 and 2.4 x 10-4 M, respectively. Inhibition of this key branch point enzyme in folate metabolism by a number of antimetabolites indicates that several of these antifolate compounds exhibit enzyme inhibition superior to that of methotrexate, a druq extensively utilized in the maintenance of remission in cancer chemotherapy.

No description available.

Inflammatory bowel disease (IBD) is a serious, complex disease that is challenging to treat effectively and affects over 5 million people globally. Current treatment goals for both subtypes of IBD, Ulcerative Colitis (UC) and Crohn Disease (CD), focus on attaining and maintaining remission through anti-inflammatory agents, immunomodulators, or biologics. In spite of these treatments, more than 25% of patients require devastating surgical removal of part of their colon due to severe inflammation. Recent advances in our understanding of serotonergic effects beyond the central nervous system (CNS) provide encouragement for IBD treatment. The newest member of serotonin receptor family, the 5-HT7 subtype, is involved in the release of pro-inflammatory cytokines following stimulation by serotonin in the gastrointestinal tract (GIT). Khan et al have shown that inflammation associated with the DSS and DNBS mouse models of IBD is significantly attenuated in knock-out mice lacking the 5-HT7 receptor or mice treated with 5-HT7 selective antagonists. Previously reported 5-HT7 receptor antagonists (e.g., SB-269970) readily crosses the blood brain barrier (BBB) and are therefore not good choices for IBD treatments. Our group has identified a novel series of arylpiperazinyl lactones with high affinity and excellent selectivity for the 5-HT7. The aim of this project is to design, synthesize, and characterize new gamma-butyrolactone-based 5-HT7 ligands with high affinity, good selectively, acceptable drug-like properties, with limited access to the CNS. A total of 18 compounds were successfully synthesized and evaluated as potential new lead compounds for the treatment of IBD. / Pharmaceutical Sciences

No description available.

This thesis explored the mechanism of action of MPTP and its toxic metabolite, MPP⁺, and compared it to the mechanism of action of haloperidol metabolites, some of which are found in schizophrenic patients. Experiments assessed the effects of these compounds on several aspects of amine uptake in mouse brain synaptosomes. Both MPTP and MPP⁺ were inhibitors of labeled neurotransmitter (serotonin and dopamine) uptake consistent with previous studies. MPP⁺ had a higher inhibitory potency in the dopaminergic system, while MPTP had a higher inhibitory potency in the serotonergic system. Haloperidol metabolites (HPP⁺, R-HPP⁺, and HPTP) also inhibited both amine transport systems with a greater affinity for the serotonergic system. Additional studies demonstrated that all of the above compounds showed reversible inhibition of serotonin uptake following drug removal by centrifugation and resuspension. In the dopaminergic system, both MPTP and MPP⁺ were reversible; however, HPP⁺ was not. This finding suggests that HPP⁺ treatment may result in irreversible poisoning of the nerve terminal or it may demonstrate a slow off-rate for its interaction with the dopamine transporter. Furthermore, HPP+ showed non-competitive inhibition of both serotonin and dopamine uptake. Amine uptake in the presence and absence of HPP* had a decreased maximal inhibitory effect and no potency change. The reversible inhibition of serotonin uptake by HPP⁺ might suggest competitive inhibition, but apparently, the comparative rates of binding and unbinding of HPP⁺ and serotonin resulted in a non-competitive interaction. These experiments support the use of MPTP as a model system for analyzing the neurotoxic potential of toxins, drug metabolites, and pesticides. The similar in vitro potencies suggest that the haloperidol derivatives could have effects similar to those of MPP⁺ in vivo. / Master of Science

No / The 5-HT1A receptor has been extensively studied over the last two decades. There is a plethora of information describing its anatomical, physiological and biochemical roles in the brain. In addition, the development of selective pharmacological tools coupled with our understanding of psychiatric pathology has lead to multiple hypotheses for the therapeutic utility of 5- and in particular 5-HT1A receptor antagonists. Over the last decade it has been suggested that 5-HT1A receptor antagonists may have therapeutic utility in such diseases as depression, anxiety, drug and nicotine withdrawal as well as schizophrenia. However, a very compelling rationale has been developed for the therapeutic potential of 5-HT1A receptor antagonists in Alzheimer s disease and potentially other diseases with associated cognitive dysfunction. Receptor blockade by a 5-HT1A receptor antagonist appears to enhance activation and signaling through heterosynaptic neuronal circuits known to be involved in cognitive processes and, as such, represents a novel therapeutic approach to the treatment of cognitive deficits associated with Alzheimer s disease and potentially other disorders with underlying cognitive dysfunction.

No / Aldehyde dehydrogenases (ALDHs) belong to a superfamily of 19 isozymes that are known to participate in many physiologically important biosynthetic processes including detoxification of specific endogenous and exogenous aldehyde substrates. The high expression levels of an emerging number of ALDHs in various cancer tissues suggest that these enzymes have pivotal roles in cancer cell survival and progression. Mapping out the heterogeneity of tumours and their cancer stem cell (CSC) component will be key to successful design of strategies involving therapeutics that are targeted against specific ALDH isozymes. This review summarises recent progress in ALDH-focused cancer research and discovery of small-molecule-based inhibitors.