Elucidating the role of CD44-Ezrin interaction in breast cancer cell invasion and drug resistance in vitro

Cancer is a debilitating disease that will affect 1 in 2 Canadians in their lifetime1. While advances in cancer care and treatment have greatly improved survival for patients, the vast majority of cancer-related deaths are due to the spread of cancer cells to distant sites within the body, known as metastasis1. Furthermore, resistance to anti-cancer therapies such as chemotherapy is a major problem limiting the effectiveness of these treatments. Therefore, understanding the molecular mechanisms regulating cancer progression and drug resistance are important for the development of novel therapeutic strategies to improve patient outcome. The cytoskeleton adaptor protein ezrin regulates a variety of cellular functions such as cell migration and survival. Ezrin’s clinical relevance as a prognostic biomarker and its potential as a therapeutic target are supported by its association with poor outcomes in breast cancer patients2, and preclinical model studies showing that genetic disruption this protein attenuates the metastatic potential of breast cancer cells and increases their sensitivity to chemotherapeutic challenges3-5. As an adaptor protein, ezrin binds to a variety of membrane-associated proteins, including the cell adhesion molecule CD44. CD44 is a transmembrane glycoprotein that mediates communication between cells and the extracellular matrix. It is a marker of tumor-initiating/cancer stem cells in many human cancers and is well documented to promote cancer cell growth, survival and invasiveness6. While both ezrin and CD44 are implicated in cancer metastasis and drug resistance, little is known about the how the CD44-ezrin interaction regulates these phenotypes. To address this, we utilize CRISPR-Cas9 gene editing technology and mutational approaches to modify the expression of, and disrupt the interaction between ezrin and CD44. Using the MDA-MB-231 human breast cancer cell line, we aim to conduct cell viability and clonogenic assays to assess changes in drug sensitivity to commonly used chemotherapy drugs. As well, migration and invasion assays will be used to evaluate the involvement of CD44-ezrin interaction on metastatic potential. By interrogating the role of CD44-ezrin interactions in breast cancer progression and drug resistance, we aim to have a better understanding of the mechanisms underlying cancer cell metastasis and treatment resistance, and to ultimately uncover potential novel therapeutic targets.