Overexpression of B7-H3 in CD14⁺ monocytes is associated with renal cell carcinoma progression

Renal cell carcinoma (RCC) is well known as a typical hypervascular tumor and has a high mortality rate. Tumor-induced angiogenesis is crucial for tumor growth and metastasis. It also plays an important role in the development and progression of RCC. However, the molecular mechanism is still unclear. In our study, we evaluated the expression level of B7-H3 in CD14⁺ monocytes in 56 paired RCC samples and distant normal tissues by flow cytometry and located the co-expression of B7-H3 and CD14 by immunohistochemistry. In addition, we analyzed its association with clinical pathologic features through Chi-square test and Fisher exact test. Results showed that B7-H3 and CD14 co-expressed in tumor stroma surrounding the vessels and that the level of B7-H3 expression was higher in tumor than in normal tissues (63.42 ± 11.92 vs. 15.59 ± 3.01, P < 0.0001). Furthermore, the expression level was significantly associated with RCC stage (P = 0.000), nodal metastasis (P = 0.003), distant metastasis (P = 0.020), and nuclear grade (P = 0.004). Conclusively, we found the phenomenon that B7-H3 and CD14 co-expressed in RCC tissues. The level of expression was closely associated with the tumor’s progression, indicating that B7-H3 might play an important role in angiogenesis of RCC mediated by CD14⁺ monocytes.