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Date of Award

4-28-2022

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Chemistry

First Advisor

Julie A. Pollock

Abstract

Epidermal growth factor receptors (EGFR) and hormone receptors (HR) are key drivers of breast cancer metastasis. Therefore, investigating the molecular interactions of protein partners in these signaling cascades is essential for the identification of new targets for therapies to combat breast cancers characterized by overexpression of EGFR and/or HR receptors. MEMO1, a 297 amino acid protein with high expression in breast cancer tumors, was previously shown to interact with the heregulin-activated ErbB2/HER2 receptor tyrosine kinase at the phosphorylated Tyr 1222, driving HER-2 dependent cell proliferation and migration. An in vitro study suggested that MEMO1 also plays a role in Estrogen Receptor 𝛼 (ER𝛼)-driven tumor aggression and ligand-independent receptor activation, by facilitating the phosphorylation of ER𝛼 at Tyr 537 by c-Src, a kinase that is phosphorylated at Tyr 418 and subsequently activated in ErbB2 signaling. Here, fluorescein-labeled peptides corresponding to the proposed c-Src and ER𝛼 phosphorylation sites were custom designed and used in Fluorescence Polarization (FP) experiments to probe the molecular interactions with MEMO1. Experimental results reveal that MEMO1 interacts weakly with c-Src in a phosphorylation-dependent manner. Conversely, MEMO1 displays a strong, phosphorylation-independent association with ER𝛼. These results convey the importance of further exploration of the molecular interaction of MEMO1 with ER𝛼 to determine its biological relevance in HR-positive breast cancers.

Available for download on Friday, May 14, 2027

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