Title: Effects Of Doxorubicin On Cardiac Fibroblast
Program: Doctor of Philosophy in Biomolecular Sciences
Advisor: Dr. Julia Oxford, Biological Sciences
Committee Members: Dr. XinZhu Pu, Biological Sciences; Dr. Allan Albig, Biological Sciences; Dr. Daniel Fologea, Physics; and Dr. Lisa Warner, Chemistry and Biochemistry
Doxorubicin is a commonly used chemotherapeutic used to treat many different types of cancer. However, its clinical use is limited due to its cardiotoxic adverse effects. While multiple mechanisms have been shown to be responsible for doxorubicin-induced cardiotoxicity, it is generally accepted that the principle mechanism is oxidative stress induction through the production of reactive oxygen species and free radicals in the myocardium. However, efforts to reduce/prevent doxorubicin toxicity using antioxidants have largely failed in pre-clinical and clinical trials. The targeted approach using a liposome delivery of doxorubicin significantly reduced the risk of cardiotoxicity; however, this approach is limited to solid tumors and not cancer that has metastasized. Therefore, continued research into doxorubicin-induced cardiotoxicity and finding measures to counter this severe adverse effect requires further investigation. Here we provide insight into how doxorubicin affects cardiac fibroblasts in their proteome, extracellular matrix deposition, and autophagic activity. Cardiac fibroblasts play a crucial role in the heart such as synthesizing and depositing the cardiac extracellular matrix, maintaining normal cardiac function, and cell-cell communication between other fibroblasts, myocytes, and endothelial cells, which affect the electrophysiological properties of the heart, and the secretion of both cytokines and growth factors. To study the effect of doxorubicin on cardiac fibroblasts, we took a multifaceted approach first by screening the cardiac fibroblasts’ proteome using tandem mass spectrometry techniques on primary cardiac fibroblasts treated with doxorubicin for 24 hours. These findings elucidated that doxorubicin-induced cardiotoxicity may be attributed to damage in cardiac fibroblasts. Downregulation of cellular communication network factor 2 was detected through mass spectrometry which led to an in vitro study on how doxorubicin affects cellular communication network factor 2 activity in cardiac fibroblasts using immunoblotting techniques and reverse transcriptase polymerase chain reaction. Lastly, we determined if autophagy was affected by doxorubicin treatments with immunoblotting and reverse transcriptase polymerase chain reaction. No significant changes in autophagy protein markers and gene expression were observed in primary cardiac fibroblasts following doxorubicin treatment, indicating that doxorubicin may not play a role in regulating autophagy in cardiac fibroblasts.