In all organs and tissues, cell behaviour is controlled by a diverse array of growth factors and hormones. These molecules act by binding to cell surface receptors, which in turn triggers activation of a range of signaling events inside cells. The Epidermal Growth Factor (EGF) Receptor (EGFR) is a critical such receptor that upon binding ligand activates signals including phosphoinositide-3-kinase (PI3K)-Akt and Ras-Erk signaling pathways. EGFR is important for many aspects of development in many organs and tissues, as well as in maintaining homeostasis in adults. Critically, EGFR is a major driver of tumor progression in several types of cancer, including triple-negative breast cancer. Thus, understanding how EGFR engages with other proteins inside cells to control cellular outcome is important for the development of new cancer therapies. 

We are interested in understanding how signaling by EGFR is impacted by nanoscale signal organization at the plasma membrane, and how this controls breast cancer cell behaviours such as proliferation, survival, and epithelial-mesenchymal transition. We use a range of advanced microscopy methods, protein-protein interaction assays, and cancer cell behaviour assays in this endeavour. We have two major projects in this area:

a) Studying the regulation of EGFR ligand binding capacity. Using single-particle tracking and other approaches, we are studying the behaviour of individual EGFR molecules in cells. This allows us to resolve the behaviour and function of different subsets of EGFR molecules, and to identify the molecular mechanisms by which proteins such as tetraspanins coordinate structural changes in EGFR that are required for ligand binding. This work has revealed a new regulatory mechanism that gates EGFR function (Sugiyama et al. Nature Comms 2023), and supported collaboration with Dr. Aidan Brown to use modeling to resolve paramaters of EGFR regulation. We are now focused on resolving the molecular mechanisms involved to identify new drug targets. 

b) Studying how activated EGFR triggers activation of PI3K-Akt signals. We use a range of fluorescence microscopy methods including total internal reflection fluorescence (TIRF), super-resolution fluorescence, and electron microscopy to study PI3K-Akt signaling molecules at the cell surface. This work has revealed that the organization of PI3K-Akt signaling proteins within clathrin-coated pits at the cell surface is required for activation of PI3K-Akt by EGFR (Garay et. al. MBoC. 2015, Cabral-Dias et al. JCB, 2022). We now aim to reveal the mechanisms by which signal organization by clathrin structures controls PI3K-Akt signals, and how this impacts cancer cell outcomes, allowing us to identify new drug targets.