Expression of Bone Morphogenetic Proteins, the Subfamily of the Transforming Growth Factor-β Superfamily, in Renal Cell Carcinoma

Purpose: We investigated the potential expression of bone morphogenetic proteins, including bone morphogenetic protein-4, 6 and 7, the largest subfamily of the transforming growth factor-β superfamily, in patients with renal cell carcinoma and identified its potential prognostic value in terms of clinical outcome. Materials and Methods: Immunohistochemical staining of paraffin sections for bone morphogenetic protein was performed in 185 cases of renal cell carcinoma using a streptavidin-peroxidase procedure. Relationships between bone morphogenetic protein expression, and clinicopathological characteristics and clinical outcome were analyzed. Results: The positive rate of bone morphogenetic protein-4, 6 and 7 expression in renal cell carcinoma was 44.3%, 20.0% and 34.1%, respectively. No statistically significant association was observed between bone morphogenetic protein immunoreactivity and age, Eastern Cooperative Oncology Group performance status and T stage. However, bone morphogenetic protein-4 expression correlated with Fuhrman grade (p = 0.034). The bone morphogenetic protein-7 expression rate was higher in female than in male patients (p = 0.007). The bone morphogenetic protein expression rate in nonclear types including chromophobe or papillary type was higher than that in the clear cell type (each p <0.001). Disease-free survival was higher in patients with bone morphogenetic protein-7 expression than in those without expression (log rank test for trend p = 0.0273). Conclusions: In the current study, the correlation between the expression of bone morphogenetic proteins and histological subtype was found. In addition, our findings suggest that bone morphogenetic protein-7 expression may be considered a new prognostic factor in renal cell carcinoma.