TC-1 Cells

TC-1 is a murine lung epithelial cell line transformed with human papillomavirus type 16 (HPV16) E6 and E7 oncogenes, along with an activated H-ras oncogene. The cell line was developed from primary lung epithelial cells of C57BL/6 mice using a dual retroviral transduction strategy. Initially, a retroviral vector derived from Moloney murine leukemia virus (MoMLV), such as pLXSN-16E6E7, was used to deliver the E6 and E7 oncogenes. In this vector, the genes are expressed from the viral 5′ LTR promoter, and a neomycin resistance gene (NeoR) under the control of an internal SV40 promoter enabled selection with G418. Stable expression of E6 and E7 results in inactivation of p53 and Rb tumor suppressor pathways, driving cell immortalization. Following initial selection, a second MoMLV-based retroviral vector encoding an activated H-ras (G12V) gene was introduced to complete transformation. This vector carried a different selectable marker, typically a hygromycin resistance gene (hph), driven by an internal promoter such as SV40 or PGK. Cells that survived sequential selection with G418 and hygromycin demonstrated stable integration of all three oncogenes, resulting in fully transformed and immortalized TC-1 cells. In functional studies, TC-1 cells exhibit strong expression of MHC class I molecules, making them highly immunogenic and widely utilized for evaluating experimental vaccines and immunotherapies targeting HPV-associated malignancies. They have been instrumental in preclinical vaccine studies, particularly those aimed at eliciting CD8+ T-cell responses against HPV16 E7. Additionally, sublines with downregulated MHC class I expression have been developed to mimic immune escape mechanisms, providing further insights into the interplay between tumor cells and host immunity. These properties make TC-1 a robust and versatile model for immuno-oncology and HPV vaccine development.