Expression And Clinical Significance Of DDR2 Protein In Clear Cell Renal Cell Cancer

Objective To explore the expression of discoidin domain receptor 2 protein(DDR2)in clear cell renal cell carcinoma(cc RCC)and normal renal tissues,and investigate its clinical and pathological significance.Methods Quantitative reverse-transcription polymerase chain reaction(q RT PCR)and Western blotting were used to detect DDR2 m RNA and protein expressions in 12 frozen renal cancer tissue specimens and 12 adjacent normal renal tissue specimens.We then used immunohistochemical analysis to explore DDR2 protein expression in 87 paraffin-embedded specimens of human cc RCC and 53 adjacent normal renal tissue specimens.These data were analyzed statistically for correlation with clinicopathologic features.Results q RT-PCR and Western blotting showed that DDR2 m RNA and protein expression levels were decreased significantly in cc RCC samples comparing with the adjacent normal renal tissues(P<0.05).Immunohistochemical analysis showed that DDR2 protein expression was positive in most normal renal tissue but negative in cc RCC samples.Moreover DDR2 protein negative expression correlated with tumor grade and stage(P<0.05).Conclusions The expression level of DDR2 was significantly decreased in cc RCC samples compared with normal renal tissues,and its decreased expression was correlated with clinical stage and histological grade,suggesting that DDR2 may play the role as tumor suppressor gene in cc RCC.