ProteinChip Array analysis of microdissected colorectal carcinoma and associated tumor stroma shows specific protein bands in the 3.4 to 3.6 kDa range.

Multiple pathways of carcinogenesis have been associated with colorectal carcinomas, including the adenoma-carcinoma sequence. The non polyposis coli gene has also been implicated in the pathogenesis of these tumors. Identification of the epithelial-mesenchymal interaction may help in understanding the pathways of invasion and may lead to the development of new, non-invasive tools for the diagnosis and prognosis of colon carcinomas. A ProteinChip Array technology (SELDI=Surface Enhanced Laser Desorption Ionization) has been developed enabling analysis and profiling of complex protein mixtures from a few cells. This study describes the protein analysis of approximately 500-1000 freshly obtained cells from normal and malignant colonic epithelium and its associated stroma by SELDI-TOF-MS (Surface Enhanced Laser Desorption Ionization Time-of-Flight Mass Spectrometry). Pure cell populations of normal and malignant epithelium as well as stroma (without tumor cells) were selected by microdissection from 9 patients. A pattern of 3 peptides of 3.48, 3.55 and 3.6 kDa, which were increased in the colon tumor epithelium and stroma compared to associated normal colon and stroma in all 9 patients, was observed. Coupling microdissection with SELDI represents a powerful tool to identify cell and tumor specific proteins and to understand molecular events underlying the invasive event in colorectal carcinomas. The presence of certain proteins in invasive carcinomas may lead to the development of non invasive biomarkers for the identification or detection of recurrence of colorectal malignancies.