Proteomic identification of angiomotin by ProteomeLab PF-2D and correlation with clinical outcome in human clear cell renal cell carcinoma.

Identification of new therapeutic and prognostic biomarkers for clear cell renal cell carcinoma (ccRCC) is urgently required since most patients are in advanced stages of ccRCC at initial diagnosis and the recurrence rate is high. Differentially expressed proteins between the ccRCC cell line RLC-310 and the normal renal cell line HK-2 were identified by a comparative proteomic approach based on a protein fractionation two-dimensional (PF-2D) liquid-phase fractionation system and capillary liquid chromatography electrospray ionization mass spectrometry/mass spectrometry (LC-ESI-MS/MS). Differentially expressed proteins (n=196) were identified. Of the 13 differentially expressed proteins newly discovered in ccRCC, angiomotin (Amot) was the focus of this study since its role in ccRCC progression has been obscure. The overexpression of Amot in ccRCC tissues was confirmed by comparing Amot expression in 18 primary ccRCC tissues and adjacent normal renal tissues (ANRT) using western blot analysis. Quantitative RT-PCR using 127 ccRCC tissues revealed that high levels of Amot transcripts were associated with poor differentiation, venous invasion and decreased survival (p<0.0001, <0.05 and <0.05). Multivariate analysis indicated that Amot transcript was an independent prognostic factor for the survival of ccRCC patients (p<0.05). These data suggest that Amot may serve as a novel prognostic factor of ccRCC.