Our lab previously studied Epidermal Growth Factor Receptor (EGFR) directed cell proliferation and differentiation in developing Drosophila. EGFR and ErbB proteins in humans are receptor tyrosine kinases that drives cell proliferation, cell survival, and differentiation. In looking for transcriptional targets of EGFR activity in Drosophila, we identified a small calcium-binding protein, CG10126, which is orthologous to human Calcyphosine (CAPS). Calcyphosine has been reported as a target of cAMP dependent kinase signaling and is related in structure to the protein Calmodulin. Several studies have shown that in humans, high levels of CAPS are present in various forms of cancer (hepatoma, ovarian cancer, ductal carcinoma, lung cancer) and associated with poor prognosis. Since EGFR activity is also increased in cancer, characterizing transcriptional targets of EGFR activation may provide novel and potential therapeutic targets for cancer treatment. The purpose of our experiment was to determine whether CAPS is a transcriptional target for EGFR signaling in human cells as CG10126 is in Drosophila. After reducing EGFR signaling using an EGF receptor tyrosine kinase inhibitor (AEE788), the amount of MAP kinase (ERK 1/2) phosphorylation and CAPS expression were measured to determine the result of EGFR inhibition on CAPS expression. Conclusively, we found inhibition of EGFR negatively regulates CAPS expression.

Sarah would like to thank her faculty sponsor Dr. Susan Spencer for their support of this project.