Solid tumor proteome and phosphoproteome analysis by high resolution mass spectrometry.

Kinases play a prominent role in tumor development, pointing to the presence of specific phosphorylation patterns in tumor tissues. Here, we investigate whether recently developed high resolution mass spectrometric (MS) methods for proteome and phosphoproteome analysis can also be applied to solid tumors. As tumor model, we used TG3 mutant mice carrying skin melanomas. At total of 100 microg of solid tumor lysate yielded a melanoma proteome of 4443 identified proteins, including at least 88 putative melanoma markers previously found by cDNA microarray technology. Analysis of 2 mg of lysate from dissected melanoma with titansphere chromatography and 8 mg with strong cation exchange together resulted in the identification of more than 5600 phosphorylation sites on 2250 proteins. The phosphoproteome included many hits from pathways important in melanoma. One-month storage at -80 degrees C did not significantly decrease the number of identified phosphorylation sites. Thus, solid tumor can be analyzed by MS-based proteomics with similar efficiency as cell culture models and in amounts compatible with biopsies.