1166 Identification of potential targets of dietary grape-mediated chemoprevention of photocarcinogenesis in SKH-1 hairless mice using global proteomics

Abstract

Ultraviolet (UV) radiation is the major contributing factor in the development of non-melanoma skin cancer (NMSC), the most common form of cancer in the United States. In recent studies, dietary antioxidants have shown promise in the management of NMSC. We have shown that dietary grape powder (GP) imparts considerable protection against UVB exposure-mediated skin carcinogenesis in SKH-1 hairless mice. Employing a quantitative global proteomics approach, here, we determined the mechanistic targets of GP, during the observed chemopreventive response in skin. UVB exposure-mediated skin tumors were excised from control and 5% GP-fed SKH-1 mice. Trypsin-digested extracts were then labeled using TMT10plex isobaric mass tagging reagents, fractionated, and analyzed by high-resolution Orbitrap LC-MS/MS. Post-acquisition analysis was performed using MaxQuant and Perseus computational software. A total of 2629 proteins were found to be modulated by GP consumption. Initial data reduction used cut-off parameters of a p-value less than 0.05, 3 unique peptides, and greater than a 1.2 fold change, resulting in 239 modulated proteins. Ingenuity Pathway Analysis (IPA) was then utilized to determine potential pathways affected by GP. IPA revealed that nine of these proteins (APCS, HP, RBP1, FGB, FGA, CRABP2, C1S, HPX, IL36G, AMBP) were linked to Acute Phase Response, a systemic response to trauma that, when prolonged, can be linked to poor cancer prognosis. After applying a more stringent filter based on a permutation FDR q-value less than 0.07, the results suggested that four of the twenty proteins affect signaling associated with the 20s proteasome (PSMA6, PSMA3 & PSMB7) and 19s proteasome (UCHL5), which play an important role in cancer as components of the 26s proteasome. Further studies are in progress in our laboratory to validate the proteomics data.