RESEARCH COMMUNICATION Clinico-Pathological Significance of MHC-I Type Chain- associated Protein A Expression in Oral Squamous Cell Carcinoma

MHC-I type chain-related protein A (MICA) is a newly discovered transmembrane glycoprotein encoded by MHC genes. MICA mainly functions as natural killer (NK) cells, cytotoxic T lymphocytes (CTLs), and other immune effector cell activation receptor NKG2D ligands. These ligands can bind NKG2D-specific proteins, transmit activation signals, induce immune effector cells to clear rapidly the tumor cells of abnormal ligand expression, and play roles in immune surveillance (Bauer et al., 1999; Wu et al., 1999; Li et al., 2001). Under normal circumstances, MICA is mainly expressed in the thymus and gastrointestinal epithelium. However, in recent years, MICA expression or overexpression has been found in numerous tumor cells, and has thus been regarded as a tumor-associated antigen (Madjd et al., 2007; Fuertes et al., 2008; Xiao et al., 2008; Zhang et al., 2008). Oral squamous cell carcinoma (OSCC) is a common malignancy of the head and neck, and knowledge on the effect of MICA expression on this cancer is limited. In the current study, we used immunohistochemistry and real-time quantitative polymerase chain reaction (PCR) to explore MICA protein and mRNA content in OSCCs. The relationship between clinical and pathological parameters was also analyzed. The aim was to increased knowledge