The Role and Regulation of Lymphocyte Oriented Kinase in RAS-driven Cancer Invasion Cancer metastasis is the most significant cause of solid tumor morbidity and mortality. Metastasis requires primary tumor cells to invade into the neighboring tissue and into the blood vessels or lymphatic system. Among a wide variety of solid tumor types, oncogenic mutations in receptor tyrosine kinases, KRAS, and BRAF give rise to a constitutively active MEK-ERK signaling pathway. Such aberrant ERK signaling leads to a migratory and invasive cancer cell phenotype. In this proposal, I aim to elucidate the molecular mechanisms of gained cell migration via hyperactive MEK-ERK signaling. I will specifically investigate a link between ERK and a novel signaling partner, Lymphocyte Oriented Kinase (LOK). LOK activity has been shown to phosphorylate/activate an important actin cortex-plasma membrane linker, Ezrin. Upregulated levels of phosphorylated Ezrin-T567 has been positively correlated with both: increased cell migration/invasion in vitro and increased metastatic potential in human cancers. In this proposal, I am going to investigate if a putative ERK-LOK-Ezrin pathway is a critical component of the invasion/metastasis machinery. Assays testing this model will include in vitro biochemical dissection, biophysical methods, high-tech imaging, and a novel mouse model. These experiments will be conducted at the Huntsman Cancer Institute (HCI), in the laboratory of Dr. Michelle Mendoza. HCI is a state-of-the-art NCI-designated Comprehensive Cancer Center. During the funding period I will undergo an extensive training regimen, involving myself with a multitude of lab/inter-lab meetings, seminar sessions, and classwork. In addition, the vast majority of techniques I propose to use are techniques I have had no experience with in the past, increasing the training benefit of this grant.
Disparate cancer types often possess common oncogenic mutations which lead to the hyper-activation of a critical signaling molecule, ERK. Dysregulation of this pathway is known to give rise to aggressive and invasive cellular phenotypes. It is the goal of this project to test if a proposed ERK substrate, LOK, is a critical component of this cellular signaling pathway.
