B7-H6 expression correlates with cancer progression and patient's survival in human ovarian cancer

B7-H6, a newly identified B7 family member molecule, binds to its receptor on NK cells, NKp30, and then triggers the anti-tumor NK cell cytotoxicity and leads to the cytokine secretion. As of now, numerous studies have demonstrated that the higher B7-H6 expression could be found in certain human cancers and have important clinical significance. In our present study, we carried out the tissue microarray and the immunohistochemistry assay to investigate the clinical significance of B7-H6 expression in human ovarian cancer. Our results showed that the positive B7-H6 staining was predominantly observed on the membrane and in the cytoplasm of the ovarian cancer cells. In order to further investigate the correlation between clinical parameters and the B7-H6 protein levels in the ovarian tissues, we categorized all the 110 patients into two major subgroups according to the intensity of B7-H6 immunohistochemical staining, i.e., the lower B7-H6 expression group, 34 cases (0 ≤ H-score < 100), and the higher B7-H6 expression group, 76 cases (H-score ≥ 100), and we found that B7-H6 expression in the ovarian cancer tissues is significantly correlated with distant metastasis status (P = 0.028) and FIGO stage (P = 0.031), whereas it is not correlated with patient's age, tumor size, tumor location, pathological stage or nodal metastasis. The survival analysis demonstrated that the overall survival rate of the subgroup with lower B7-H6 expression is significantly better than that of the subgroup with higher B7-H6 expression (P = 0.0456, Hazard Ratio: 1.707, 95% CI, 1.010-2.885). Thus, our present data revealed that higher B7-H6 expression in ovarian cancer tissues was positively correlated with tumor metastasis and cancer progression, and supports the notion that B7-H6 expression is involved in the progression of human ovarian cancer, the detailed mechanism merits further investigation.