Trophoblast Glycoprotein (5T4) is Expressed on the Renal Cell Carcinoma (RCC) and Colorectal Cancer (CRC) Tumor Cells and Recognized by Cytotoxic T Lymphocyte
Date of Award
Restricted Access Thesis
College of Theology, Arts, & Sciences
Math & Science
Dr. Rici Hallstrand
Renal Cell Carcinoma (RCC) and Colorectal Cancer (CRC) rank among the top 10 most common cancers in the United States. In 2009, it is estimated that there will be 146,970 and 57,760 new cases of CRC and RCC respectively (ACS). Trophoblast Glycoprotein (TPBG), also known as 5T4 is a 72kDa tumor-associated antigen expressed on the majority of RCC and CRC. Given that 5T4 is highly expressed on tumors but has restricted expression on normal cells, a cancer vaccine targeting 5T4 was previously created as a recombinant vaccinia virus (MVA-5T4) (Harrop et al., 2006). RCC and CRC patients vaccinated with MVA-5T4 have shown to elicit 5T4-specific humoral and cellular immune responses; however, the 5T4-specific T cells’ antitumor effects have not been characterized in vitro. We developed a semi-quantitative real-time Polymerase Chain Reaction (RT-PCR) assay to analyze 5T4 transcript expression in tumor cells and a normal tissue array. The RT-PCR demonstrated preferential 5T4 transcription within tumors, which 5T4 protein expression was also confirmed by flow cytometry in corresponding RCC and CRC tumor cells. Cytotoxic T lymphocyte (CTL) clones specific for an HLA-A2 binding peptide from 5T4 were then tested in Chromium Release Assays for recognition of MVA-5T4 infected target cells and 5T4-expressing tumor cell lines. The assay demonstrated robust anti-tumor lytic activity of tumor cells. These results validate 5T4’s potential as a target for T cell based immunotherapy and contributed to better understanding of 5T4 expression for the advancement of MVA-5T4 cancer vaccine.