Date of Award

8-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Biomedical Sciences

Track

Cancer and Developmental Biology

Research Advisor

Yi Lu, Ph.D.

Committee

Andrzej T. Slominski, Ph.D. Wei Li, Ph.D. Leonard Lothstein, Ph.D. Ram I. Mahato, Ph.D.

Keywords

Angiogenesis, Breast Cancer, Hypoxia Inducible Factor 1α, Metastasis

Abstract

The current clinical chemotherapy agents are not ideal for breast cancer as they are not curative, but only provide a modest extension of survival with sometimes a severely adverse effect on the patient’s quality of life. There is, therefore, an urgent need to search for new and more effective anti-breast cancer drugs. However, the existing screening system is inefficient and time-consuming despite the extremely large amount of small molecule compounds in database currently available, and thereby hindering the effort for selecting new and effective anti-cancer drugs.

The majority of locally advanced solid tumors contain regions of reduced oxygen availability. Hypoxia has been identified as a major negative prognostic factor for tumor progression and resistance to anti-cancer therapies. Hypoxia promotes cell proliferation, immortalization, genetic instability, and induces cells to switch their methods of glucose metabolism, a normal response to proliferation. In animal models, HIF-1 (a heterodimer composed of one of the three alpha subunits-HIF-1α, HIF-2α or HIF-3α- and one constitutively expressed HIF-1β subunit) overexpression is associated with increased tumor growth, vascularization, and metastasis. The goal of this project, therefore, is to identify a novel compound with anti-HIF-1α activity, using an efficient high-throughput screening system that has the capability to screen large numbers of potential anti-cancer drugs.

Because HIF-1α is the transcriptional regulator for a group of malignant-pathway related genes (including VEGF) and it promotes the tumor progression and metastasis, identification of novel anti-HIF-1α agents will lead to effectively blocking of HIF-1α-mediated “switch-on” function for those malignant-pathway related genes, and thus the suppression of VEGF signaling pathway and breast cancer progression and metastasis.

To screen for effective anti-HIF-1α compounds, human breast cancer cells treated with or without candidate compounds were transfected with a chimeric construct containing a VEGF promoter fused to a reporter gene luciferase (pVEGF-Luc), followed by incubation in the hypoxic conditions. As the HIF-1α-mediated VEGF transactivation was reflected by increased luciferase activity, the potential anti-HIF-1α effect of the compound were identified by its significant reduction of luciferase activity compared to the untreated control.

Given its potential for systemic administration and targeting, an anti HIF-1α compound could prove useful as a therapy against breast carcinoma growth and invasion. We propose that down regulation of HIF-1α by anti HIF-1α drug will lead to a decrease in the level of hypoxiainduced genes including VEGF, subsequently resulting in the inhibition of tumor growth, decrease metastasis to surrounding organs, block tumor metastasis and increase survival in breast carcinoma animal model.

DOI

10.21007/etd.cghs.2012.0192

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