The clinical and biological significance of MICA in clear cell renal cell carcinoma patients

Major histocompatibility complex class I-related chains A (MICA), a ligand of Natural killer group 2, member D (NKG2D) receptor, is broadly upregulated in epithelial originated tumor cells. MICA plays a critical role in the immune surveillance against tumor cells and is associated with the prognosis of several malignancies. The aim of this study is to evaluate the clinical and biological significance of MICA in clear cell renal cell carcinoma (ccRCC). The expression of MICA was analyzed by quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC). Both MICA mRNA and protein levels were upregulated in ccRCC tissues, compared with normal tissues. IHC staining revealed a homogenous pattern of MICA staining within each tumor, which combined both membrane staining and granular cytoplasmic staining. Furthermore, high MICA expression was associated with lymph node metastasis and advanced clinical stage and predicted poor prognosis in patients with ccRCC. Gene set enrichment analysis (GSEA) was performed using RNA-sequencing data from The Cancer Genome Atlas Research Network (TCGA) to elucidate the biological role of MICA in ccRCC and revealed that MICA was significantly associated with the epithelial-to-mesenchymal transition (EMT) gene set, which was further confirmed by qRT-PCR. Our findings contribute to the studies on biomarkers of kidney cancers and the mechanism of renal cancer progression driven by EMT pathway.