Electronic Theses and Dissertations

Date of Award

2019

Document Type

Dissertation

Degree Name

Ph.D. in Pharmaceutical Sciences

Department

Pharmaceutics and Drug Delivery

First Advisor

Kristine Willett

Second Advisor

Tracy Brooks

Third Advisor

Asok Dasmahapatra

Relational Format

dissertation/thesis

Abstract

Breast Cancer (BC) is the most frequently diagnosed cancer; 1:8 women are at risk of developing BC in her lifetime. Cancer metastasis causes the majority of deaths in BC patients. Moreover, side effects of traditional chemotherapeutic drugs (TCD) impair the quality of life of these patients. Discovery and development of safe and effective new therapies is imperative for the treatment of BC and targeting metastasis. The goal herein is to further expand the applicability of in vivo xenotransplantation of human BC cells in transgenic zebrafish to screen potential chemotherapeutics for toxicity and efficacy. For xenotransplantation, MCF-7, BT-474, and MDA-MB-231 BC cells were used to canvas the benign and malignant types of BC, respectively. Using fluorescently-labeled cells, the cytotoxic effect of doxorubicin, 4-hydroxytamoxifen, and paclitaxel were determined using a cell viability assay. Test compounds (fractions of Tinospora crispa and potent microtubule inhibitors) were also tested for in vitro cytotoxicity. Maximally tolerated concentrations (MTCs; >80% survival) and no observed adverse effect level (NOAELs) for developmental morphology were determined in zebrafish following a 96 hr waterborne exposure to 1 - 50 µM of doxorubicin, 4-hydroxytamoxifen, paclitaxel, and curcumin or 10 - 800 nM of mertansine, ansamitocin P-3, and monomethyl auristatin E (MMAE). NOAELs for paclitaxel, mertansine, ansamitocin P-3, and MMAE were 25, 400, 50, and 400 nM, respectively. Zebrafish were xenotransplanted with MCF-7, BT-474, and MDA-MB-231 cell lines to observe the effects of exposure to microtubule inhibitors on the proliferation of cancer cells. After xenotransplanting 50-100 BC cells/larva at 2 days post-fertilization, cell growth and migration were imaged at 1 and 5 days post-injection using fluorescent microscopy. Paclitaxel (25 nM) and mertansine (10 and 200 nM) significantly reduced the proliferation of MCF-7 cell xenografts compared to controls, confirming the use of this model for MCF-7 cell xenografts. In contrast, MDA-MB-231 xenografts did not respond to the same concentrations of PTX or mertansine. Here, we developed an optimized assay and quantitative approach to screen novel anti-cancer agents against breast cancer xenotranplants.

Available for download on Tuesday, September 22, 2020

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