Abstract
B7-H3, a novel member of the B7 family, was previously known as a regulatory ligand regulating T-cell-mediated immune response, and in recent years it was found to take a significant role in various cancers. In some tumor types, high expression of B7-H3 had been linked to a poor prognosis, whereas in other cancers the opposite effect had been observed. The precise role of B7-H3 in tumor immunity is unclear, and further investigations are needed. In the present study, we studied the expression of B7-H3 in the pathologic specimens of 221 patients treated for breast cancer by immunohistochemistry. Strong B7-H3 expression was found in cancer tissues from 80.55% patients, and B7-H3 expression had a negative relation with vascular endothelial growth factor (VEGF) expression, microvascular density for CD34, and tumor size. Furthermore, through lipopolysaccharide-mediated delivery of stable short hairpin ribonucleic acid we observed that silencing of B7-H3 could increase the transcription and secreting of VEGF in breast cancer cell line MCF-7. In summary, the present study demonstrated that B7-H3 suppressed tumor growth through inhibiting VEGF expression. These results increased knowledge of the nonimmunological role of B7-H3 protein and provided novel insights into great biological functions and a putative therapeutic target in breast cancer.