Expression of Platelet-Derived Growth Factor-aa Receptor Is Associated With Tumor Progression in Clear Cell Renal Cell Carcinoma

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Abstract
Platelet-derived growth factors (PDGFs) exert their biologic function by binding to 3 different tyrosine kinase receptor isoforms. Especially the PDGF-α receptor binds PDGF proteins with high specificity, which results in growth stimulation. The expression of the receptor and its ligand was studied in human renal cell carcinomas (RCCs) by immunohistochemical analysis, and the expression of PDGF-α receptor and PDGF-AA was correlated with clinicopathologic parameters of patients with clear cell RCC (CCRCC). In CCRCC, the mean expression of PDGF-α receptor and PDGF-AA was 38.8% (range, 0.0%–96.0%) and 18.4% (range, 0.0%–90.0%), respectively. PDGF-α receptor expression was significantly higher in grade 3 and grade 4 tumors compared with grade 1 and grade 2 tumors (P = .027; Mann-Whitney test), and high receptor expression correlated with tumor progression in univariate analysis (P = .0253; log-rank test), while PDGF-AA expression had no prognostic influence on the outcome of patients with CCRCC. Therefore, immunohistochemical detection of high PDGF-α receptor expression in CCRCC is associated with adverse outcomes. Furthermore, the PDGF receptor-factor interaction loop may be considered as a possible target for novel therapeutic strategies.