Preliminary analysis of differentially expressed proteins of clear-cell renal cell carcinoma by comparative proteomic technologies

Objective: To explore the different expression of proteins between human clear-cell renal cell carcinoma (ccRCC) cell line RLC-310 and normal renal proximal tubule epithelial cell line HK-2, and to search new differentially expressed proteins of RCC. Methods: RLC-310 and HK-2 cells were cultured in vitro. The total proteins were separated by ProteomeLab PF 2D protein fractionation system and the differential expression protein fractions of the two cell lines were analyzed and identified by capillary liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS). RT-PCR and Western blot were used to confirm the representative differential expression at mRNA and protein levels. Results: One hundred and ninty-six differentially expressed proteins were identified. These differentially expressed proteins involved in many aspects, including cell proliferation and anti-apoptosis, energy metabolism, mitochondria reduction and oxidation, oxidative stress and resistance, cell signaling, invasion and adhesion, cytoskeleton and motion, neovascularization, etc. Except for previously reported RCC associated proteins: annexin A2, fatty acid-binding protein, vimentin, fibronectin, and so on, Septin-9 was firstly found highly expressed in RLC-310 cells when compared with that in the HK-2 cells. Moreover, the overexpression of Septin-9 was confirmed by RT-PCR and Western blot analysis at both mRNA and protein levels (P < 0.05). Conclusions: The human ccRCC cell line RLC-310 cells display differential protein profiles compared with those of the normal renal cell line HK-2 cells. The identified differential expression proteins are involved in many aspects of RCC development. It is worth further study and elucidate the molecular mechanisms of RCC. The representative differential protein Septin-9 deserves further study its role in the angiogenesis of ccRCC.