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Characterization of Cytokeratin 8 in Cancer

By Daniel S. Leventhal | Mentor: Dr. Mark T. Muller

Abstract

A Cytokeratin 8 (K8)/Green Fluorescent Protein (GFP) fusion construct was created to better understand the behavior of K8 within cancer cells. This intermediate filament (IF) protein is a member of the cytoskeletal gene family, along with actin and tubulin. IFs are normally expressed in a tissue-specific and differentiation-dependent manner, in which their role is more supportive than essential to the cell. Such roles include rigidity of cellular shape, protein trafficking, cellular locomotion, and cell-signaling platforms. K8 mutation, over-expression, and aberrant post translational modifications have been observed in various carcinoma cell lines to be the cause of several phenotypes, including apoptosis inhibition, drug resistance, transformation, Mallory-Denk body formation, localization at the plasma membrane, and secretion of the protein.

To study these abnormal phenotypes, the K8 gene was isolated and inserted into the GFP over expression vector. Transfecting this vector into HeLa cells allowed for the study of K8 within a well-defined cervical cancer cell line. This study was intended to provide answers to K8’s localization at the plasma membrane in carcinoma cell models while avoiding criticisms to previous immunohistochemical localization studies. A cellular model of K8 processing that exhibits established phenotypes found in the literature was thus created and has the potential to address several paramount questions related to K8’s role in supporting the development and progression of cancer. It could also be utilized as an assay for the discovery of K8 filament formation inhibitors, which may prove useful in combination with current chemotherapeutics. The model could also be used to provide weight to diagnostics, such as the CAncer REcognition test, which utilizes antibodies against K8 as biomarkers for malignancy via an Enzyme-Link ImmunoSorbent Assay.

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