Prognostic value of soluble MICA levels in the serum of patients with advanced hepatocellular carcinoma

Serum levels of soluble MHC class I-related chain A (sMICA) are related with the prognosis of various types of cancer; however, few studies on the prognostic value of sMICA in hepatocellular carcinoma (HCC) have been reported. In this study, we retrospectively investigated the relationship between sMICA levels and clinical features of advanced HCC, and we assessed the prognostic value of sMICA in advanced HCC. Furthermore, the relationship of serum sMICA levels and natural killer group 2, member D (NKG2D) expression on natural killer (NK) cells was also evaluated. We detected sMICA levels in the serum of 60 advanced HCC patients using enzyme-linked immunosorbent assay (ELISA) and measured expression levels of NKG2D on NK cells using flow cytometry. We found that serum sMICA levels in HCC patients were in the range of 0.10-6.21 ng/mL. Chi-square analyses showed that sMICA level was significantly related with only tumor size. Survival analysis showed that a high sMICA level was significantly related with poor prognosis among HCC patients. Multivariate analyses indicated that sMICA was an independent prognostic factor. In addition, the levels of CD56(+)NKG2D(+) NK cells were within the range of 11.2%-55.4%, and correlation analyses indicated that sMICA level was negatively correlated with the level of NKG2D(+) NK cells. Our results suggest that serum sMICA levels may be an independent prognostic factor for advanced HCC.