Analysis of the Effects of Tgf-β Mediated Reduction of Caveolin-1 Expression Following Fibroblast Interaction with a Biological Extracellular Matrix

Date of Award

5-2017

Degree Type

Thesis

Degree Name

Master of Science in Biomedical Sciences

First Advisor

Abigail Hielscher

Second Advisor

Charles Daniels

Third Advisor

Xinyu Wang

Fourth Advisor

Richard E. White

Abstract

Breast cancer is the most commonly diagnosed cancer in women worldwide. Though extensive work has been done to address the underlying mechanism of disease to develop novel therapeutic agents, only recently has the focus been shifted from breast cancer cells to the tumor microenvironment. Caveolin-1 (cav-1), a scaffolding protein of caveolae, has been directly implicated in poor prognosis when downregulated in breast cancer. To determine whether fibronectin works directly to downregulate cav-1, we plated human mammary fibroblasts (HMFs) on fibronectin derived from human plasma and observed changes in cav-1 at 24 and 48 hours. We found that fibronectin alone does not downregulate cav-1, and were unable to investigate any mechanism linking the two. However, TGF- β has been implicated in cav-1 downregulation, and it has been shown that fibronectin matrix sequesters TGF- β via LTBP-1 in the matrix. We investigated HMFs for the presence of LTBP-1 via immunofluorescence and western blot, and found that it is expressed. In addition, we found that LTBP-1 is co-localized with fibronectin in the extracellular matrix (ECM) deposited by HMFs. Additionally, we generated biological ECM for use in experiments investigating the role of ECM in concert with TGF- β in downregulating cav-1. We found that after 24 and 48 hours, there is no significant change in cav-1 expression in HMS. However, after 72 hours, biological ECM interacts with TGF-β to significantly downregulate caveolin-1 in HMFs (p

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