Whole cell profiling and identification of galectin-1 as a potential marker of renal cell carcinoma

For most cancers, the patient's prognosis improves dramatically if the disease is detected at an early stage. Although advancements in imaging technology have improved early detection, many cancers remain undetected until it is too late for curative intervention. We have established, for the first time, expression difference mapping analysis of whole cell proteins from renal cell carcinoma (RCC) cell lines using ProteinChip technology. A total of 20 different RCC cell lines were cultured in vitro directly on ProteinChip arrays for 24 h. Direct MS analysis of proteins from the attached cells showed identical protein profiles by all analysed RCC lines. Comparative on‐chip analysis of isolated malignant cells from native tumour specimens revealed protein patterns highly similar to those from the continuous RCC lines. However, cultured primary cortex cells showed specific protein differences. Differential protein profiling of isolated cytosolic and enriched membrane fractions from the RCC lines revealed that the protein pattern of the membrane proteins included or were identical to those of the entire cells. Proteomics analysis of the chip‐binding membrane fractions allowed the identification of three forms of galectin‐1 as potential RCC marker. ProteinChip analysis with a bound‐specific antibody certified that galectin‐1 could be an RCC marker. Immunostaining methods confirmed the overexpression of galectin‐1 in renal carcinoma in comparison to healthy tissue.