Salivary proteomic profile of patients with renal cell carcinoma.

622 Background: We aimed to explore the salivary proteomic profile (SPP) of patients undergoing surgery for suspected renal cell carcinoma (RCC), then evaluate any significant findings in a validation cohort. Methods: Prospective IRB approved trial of consecutive patients with suspected RCC undergoing curative surgery. Saliva was collected pre- and postoperatively, and from healthy volunteers. Saliva was mixed with sodium orthovanadate and protease inhibitor, aliquoted, and frozen at -80oC. SPP performed using biomarker concentrated saliva via core-shell hydrogel nanoparticles functionalized with molecular baits coupled to high resolution MS/MS electrospray mass spectrometry analysis; output represented as spectral counts. Wilcoxon Rank Sum test was used for comparisons; p-values were adjusted using false discovery rate (FDR) for multiple testing. Results: Exploratory phase: saliva was collected from 27 volunteers and 34 RCC patients (24 clear cell (cc)RCC, 6 chromophobe (ch)RCC, 4 other). Evaluation of cc vs chRCC revealed differential counts for 56 proteins; none were significant after adjustment by FDR. Comparison of matched pre/post-operative SPP in 14 ccRCC patients identified differential counts of 3 proteins: basic salivary proline-rich protein 3 precursor; prolactin-inducible protein precursor; and submaxillary gland androgen-regulated protein 3B precursor. These were not affected by patient age, partial/radical nephrectomy, or tumor size/stage/grade. Validation phase: power analyses indicated a sample size of 38/53 patients = 90% power = effect size of 0.6/0.5, respectively, 2-sided Type 1 error of 0.025. 49 ccRCC patients were enrolled with pre/postop saliva. 611 proteins were identified; none had differential counts after FDR. Conclusions: Using a unique biomarker technology coupled to high resolution MS, interesting SPP’s were seen between RCC subtypes and before/after ccRCC curative resection. We were unable to show significant differences in pre/post-op levels. More research is needed to further study the SPP in RCC patients and the factors impacting their differential expression. In order to aid such efforts, the raw data will be made available for future researchers.