Esophageal cancer is a common malignancy in the United States and worldwide. A number of studies indicate that the molecular basis of esophageal squamous cancer cell carcinoma (ESCC) involves the activation of oncogenes and tumor suppressor genes, but the role of epidermal growth factor receptor (EGFR) in the very early stages of carcinogenesis remains elusive. We have overexpressed EGFR through retro-virally-mediated transduction in different primary human esophageal epithelial cells. This has led to observations that there are coordinated consequences of enhanced cell migration modulated by EGFR. In addition, when EGFR overexpressing primary human esophageal epithelial cells are placed in a novel, organotypic cell culture system, there is induction of increased epithelial thickness, hyperplasia, and hyperproliferation. Our hypothesis is that EGFR plays a critical role in the disruption of normal cellular homeostasis through induction of hyperproliferation and enhanced cell migration with impairment of differentiation. The objectives will be achieved through the following interrelated Specific Aims: (1) To determine the functional activation of Akt by EGFR and determine the possible link between upregulation of STAT-1 and matrix metalloproteinases (MMPs) as modulators of cell migration and (2) To elucidate the role of EGFR in promoting increased cell proliferation through the induction of RAD (ras like molecule), a GTP binding protein that is negatively regulated by the nm-23 metastasis suppressor gene. RAD was found to be upregulated based upon a gene array comparison of esophageal epithelial cells retrovirally transduced with green fluorescent protein (GFP) versus EGFR. ? In aggregate, the proposed studies will provide new insights into EGFR signaling and modulation of key cellular processes in the esophageal epithelium as the basis for the very early steps in esophageal squamous carcinogenesis. These data will provide a foundation for future studies in transgenic mouse models and a transition towards an R01 grant proposal. ? ?
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