title: Protein pathway biomarker analysis of human cancer reveals requirement for upfront cellular-enrichment processing.
abstract: Tissues are complex structures composed of different cell types, each of which present specific functions and characteristics. To better understand and measure the effect of tumor cell enrichment on protein pathway profiling and drug target activation measurements, the signaling activation portraits of laser capture microdissected (LCM) cancer epithelium and tumor stroma were compared with patient-matched whole-tissue specimens from 53 primary colorectal cancer samples. Microdissected material and whole-tissue lysate from contiguous cryostat sections were subjected to reverse-phase protein microarray analysis to determine the level of phopshorylation and expression of 75 different proteins known to be involved in cancer progression. The results revealed distinct differences in the protein activation portraits of cancer epithelium and stroma. Moreover, we found that the signaling activation profiles of the undissected whole-tissue specimens are profoundly different from the matched LCM material. Attempts to rescale the undissected pathway information based on percent endogenous tumor epithelium content were unsuccessful in recapitulating the LCM tumor epithelial signatures. Analysis of epidermal growth factor receptor phosphorylation and COX2 expression in these same sample sets revealed wholesale differences in the rank ordering of patient determination when LCM was compared with undissected samples. On the basis of these data, we conclude that accurate protein pathway activation status, which is under evaluation as a basis for patient selection and stratification for personalized therapy, must include upfront cellular-enrichment techniques such as LCM to generate accurate drug target activation status.
authors.affiliation: Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA, USA.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Silvestri
authors.forename: Alfonso
authors.initials: A
authors.lastname: Colombatti
authors.forename: Valerie S
authors.initials: VS
authors.lastname: Calvert
authors.forename: Jianghong
authors.initials: J
authors.lastname: Deng
authors.forename: Enzo
authors.initials: E
authors.lastname: Mammano
authors.forename: Claudio
authors.initials: C
authors.lastname: Belluco
authors.forename: Francesco
authors.initials: F
authors.lastname: De Marchi
authors.forename: Donato
authors.initials: D
authors.lastname: Nitti
authors.forename: Lance A
authors.initials: LA
authors.lastname: Liotta
authors.forename: Emanuel F
authors.initials: EF
authors.lastname: Petricoin
authors.forename: Mariaelena
authors.initials: M
authors.lastname: Pierobon
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D015153:Blotting, Western; D016000:Cluster Analysis; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D007834:Lasers; D046228:Microarray Analysis / Q000379:methods; D042282:Microdissection / Q000379:methods; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D011506:Proteins / Q000032:analysis* / Q000145:classification; D040901:Proteomics / Q000379:methods; D015398:Signal Transduction
chemical_list: D014408:Biomarkers, Tumor; D011506:Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D066246:ErbB Receptors