MHC class i molecules and cancer progression: Lessons learned from preclinical mouse models

Abstract

Major histocompatibility complex (MHC) class I molecules are expressed on the surface of nucleated cells and present peptides derived from endogenous proteins to CD8+ T-lymphocytes. In tumor cells, MHC class I (MHC-I) molecules may present peptides derived from tumor-associated antigens (TAAs), which are new proteins expressed or overexpressed in tumor cells. Presentation of these new peptides may allow recognition and destruction of tumor cells by CD8+ T-lymphocytes. Loss of MHC-I expression on tumor cells is a widespread and frequent mechanism developed to escape from immunosurveillance. Alteration in MHC-I in both human and murine experimental tumors has been widely reported. This chapter summarizes the role of MHC class I expression on cancer cells in tumor and metastatic progression, as well as its effect on the outcome of immunotherapy in murine experimental tumors. Results were obtained from different tumor clones derived from a fibrosarcoma induced by methylcholanthrene (MCA) in BALB/c mice, in addition to spontaneous metastases derived from these tumor clones, during more than 30 years of study on murine cancer model GR9. In this tumor model, results show an inverse correlation between MHC-I expression on tumor cells and primary tumor growth, i.e., MHC-I-negative tumors grew more rapidly compared to MHC-I-positive tumors. In contrast, a direct correlation was found between MHC-I expression on primary tumors and spontaneous metastatic capacity. Immunotherapy as an antimetastatic treatment was completely effective against MHC-I highly positive tumors and was partially effective on tumors with an intermediate level of MHC-I expression.