Differential Protein Expression in Renal Cell Carcinoma: Biomarker Discovery and Clinical Applications
GM Yousef, CJ Streutker, Y Youssef, KWM Siu, L DeSouza, M Gabril, AD Romaschin. St. Michael's Hospital, Toronto, ON, Canada; York University, Toronto, ON, Canada; London Health Sciences Center, London, ON, Canada
Background: Renal cell carcinoma (RCC) is the most common neoplasm in the adult kidney. Unfortunately, there are currently no biomarkers for the diagnosis of RCC. In addition to early detection, biomarkers have potential use for prognosis, monitoring recurrence after treatment, and as predictive markers for treatment efficiency.
Design: In this study, we identified proteins that are dysregulated in RCC, utilizing a quantitative mass spectrometry analysis. We compared the protein expression of kidney cancer tissues to their normal counterparts from the same patient using LC-MS/MS. iTRAQ labeling permitted simultaneous quantitative analysis of four samples (cancer, normal, and two controls) by separately tagging the peptides in these samples with four cleavable molecular weight tags (114, 115, 116, and 117). The samples were then pooled and the tagged peptides resolved first by strong cation exchange chromatography and then by nanobore reverse phase chromatography coupled online to nano-electrospray MS/MS.
Results: We identified a total of 937 proteins in two runs. There was a statistically significant positive correlation of the proteins identified in both runs (rp = 0.695, p < 0.001). Using a cutoff value of 0.67 fold for underexpression and 1.5 fold for overexpression, we identified 168 underexpressed proteins, and 156 proteins that were overexpressed in RCC compared to normal. These dysregulated proteins in RCC were statistically significantly different from those of urothelial carcinoma and end-stage glomerulonephritis. We performed an in-silico validation of our results by different approaches. We also experiemtally validated our findings by Western blotting. In silico analysis showed that many of these proteins are involved in cancer-related pathways and can serve as potential diagnostic and/or therapeutic targets.
Conclusions: Our results suggest that protein expression profile in RCC is significantly different from that of other kidney diseases. Identified proteins have the potential as tumor markers. Larger scale analyses are needed to examine whether these proteins are consistently differentially expressed in RCC.
Category: Genitourinary (including renal tumors)
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 109, Wednesday Afternoon