Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, School of Molecular and Cell Biology, 2018. / ABSTRACT The Retinoblastoma binding protein 6 is dysregulated in most cancers, indicating it may play a role in metabolic reprograming- a hallmark of carcinogenesis. Its human isoforms have been shown to play diverse roles in apoptosis. This study aimed to elucidate biochemical roles of RBBP6 isoforms in metabolic reprogramming during carcinogenesis. Drosophila melanogaster wild type and p53 null mutants were treated with drug permutations of irinotecan (DNA damaging agent) and exogenous pyruvate to perturb metabolism. Moreover, using RT-PCR and Western blot expression profiles of SNAMA (Drosophila Orthologue of RBBP6) isoforms were shown followed by survival studies to investigate the effects of these drugs. Furthermore, using bioinformatics the domains of RBBP6 isoforms in various species were shown. Results indicate that RBBP6 isoforms show contrasting expression patterns. Furthermore, exogenous pyruvate protects the wild type flies from irinotecan toxicity while killing p53 null mutants. RBBP6 proves to be a potential druggable target for chemotherapy. / EM2018

Matrix Metallopeptidase 1 (MMP-1) expression has repeatedly been correlated to tumorigenesis and metastasis. Yet, MMP-1 regulation in a metastatic context remains largely unknown. Here we confirm differential MMP-1 expression in mammary carcinoma cells with varied metastatic potentials and identify a mechanism differentially regulating MMP-1. We show that MMP-1 expression is regulated by an AP-1 element in its promoter in highly metastatic MDA-MB-231 mammary carcinoma cell derivatives. Fra-1, an AP-1 family transcription factor, differentially binds this element in highly metastatic derivatives compared to low-metastatic cells and is required for MMP1 expression. Fra-1 mRNA levels are unchanged in the cell variants, however its protein levels are higher in the metastatic cells. There was no change in protein degradation rates, while protein synthesis rates of Fra-1 increased. These results suggest that protein translation of Fra-1 is differentially regulated in these cells. Consistent with the importance of Fra-1 for tumor growth, we found that Fra-1 overexpression is sufficient to increase cell motility and anchorage independent growth. These results suggest that Fra-1 regulation is critical for regulation of MMP-1 and metastasis.

No description available.

No description available.

Colon cancer is the third most common cancer in the United States. However, evidence indicates that a proper diet abundant in fruits and vegetables may be protective against colon cancer development. Bioactive compounds in fruits and vegetables, such as flavonoids and limonoids, have been shown to possess anti-proliferative and antitumorigenic effects in various in vitro and in vivo models of cancer. Since there are few animal studies involving flavonoids and limonoids and colon cancer, this experiment investigated the potentially protective effects of four citrus flavonoids and one limonoid mixture against the promotion stage of chemically-induced colon cancer in rats. Male SD rats (n =60; 10 rats/group) were assigned to receive diets containing 0.1% apigenin, 0.02% naringenin, 0.1% hesperidin, 0.01% nobiletin, 0.035% limonin glucoside/obacunone glucoside mixture, or a control diet (0% flavonoid/limonoid). Rats received the diets for 10 wk and were injected with azoxymethane (15 mg/kg) at wk 3 and 4. The excised colons were evaluated for aberrant crypt foci (ACF) formation, cell proliferation (PCNA assay), apoptosis (TUNEL assay), and iNOS and COX-2 expression. When compared to the control diet, apigenin lowered the number of high multiplicity ACF (> 4 AC/focus) by 57% (P<0.05) and tended to lower the proliferative index (28%; P=0.07), while naringenin lowered both the number of high multiplicity ACF by 51% (P<0.05) and the proliferative index by 32% (P<0.05). Both apigenin and naringenin increased apoptosis of surface colon cells (78% and 97%, respectively; P<0.05) when compared to control diet. Hesperidin, nobiletin, and the limoninglucoside/obacunone glucoside mixture did not have any effects on the above variables measured in this model of colon carcinogenesis. The colonic mucosal protein levels of iNOS or COX-2 were not different among the six diet groups. Evidence suggests that high multiplicity ACF are indicative of future tumor development in both humans and rats. Furthermore, dysregulated proliferation and apoptosis may also lead to tumorigenesis. Therefore, the ability of dietary apigenin and naringenin to reduce high multiplicity ACF, lower proliferation, and increase apoptosis may contribute toward colon cancer prevention. However, their protection is not due to their influence on iNOS and COX-2 protein levels.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 171-225). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 171-225). Also available on the Internet.

Thesis (Ph. D.) in Biochemistry and Molecular Biology--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 97-113).

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 77-100). Also available in print.

published_or_final_version / abstract / Pathology / Doctoral / Doctor of Philosophy