Comparative study of gene expression by cDNA microarray in human colorectal cancer tissues and normal mucosa

The causative molecular pathways underlying the pathogenesis of colorectal cancer (CRC) need to be better characterized. The purpose of our study was to better understand the genetic mechanism of oncogenesis for human colorectal cancer and to identify new potential tumor markers of use in clinical practice. We used cDNA microarrays to compare gene expression profiles of colorectal biopsies from 25 CRC patients and 13 normal mucosa from adjacent non-cancerous tissues. Findings were validated by real-time PCR; in addition, western blotting and immunochemistry analysis were carried out as further confirmation of differential expression at a protein level. Comparing cancerous tissues with normal colonic mucosa we identified 584 known genes differentially expressed to a significant degree (p<0.001). Many of the transcripts that were more abundant in tumors than in non-neoplastic tissues appear to reflect important events for colon carcinogenesis. For example, a significant number of these genes serve as apoptotic inhibitors (e.g. BFAR, BIRC1, BIRC6). Furthermore, we observed the simultaneous up-regulation of HLA-E and the down-regulation of beta2-microglobulin; these genes strongly support a potential tumor escape strategy from immune surveillance in colon cancer tissues. Our study provides new gene candidates in the pathogenesis of human CRC disease. From our results we hypothesize that CRC cells escape immune surveillance through a specific gene expression alteration; moreover, over-expression of several survival genes seems to confer a more anti-apoptotic phenotype. These genes are involved in pathways not previously implicated in CRC pathogenesis and they may provide new targets for therapy.Fil: Bianchini, Michele. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; ArgentinaFil: Levy, Estrella Mariel. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Zucchini, Cinzia. Università di Bologna; ItaliaFil: Pinski, Victor. Universidad de Buenos Aires; ArgentinaFil: Macagno, Carlo. Universidad de Buenos Aires; ArgentinaFil: De Sanctis, Paola. Università di Bologna; ItaliaFil: Valvassori, Luisa. Università di Bologna; ItaliaFil: Carinci, Paolo. Università di Bologna; ItaliaFil: Mordoh, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; Argentin

First amyloid β1-42 certified reference material for re-calibrating commercial immunoassays

INTRODUCTION: Cerebrospinal fluid (CSF) concentration of amyloid β peptide (Aβ42) is a key biomarker for Alzheimer’s disease (AD), reflecting brain amyloidosis. Reference materials based on human CSF were certified for the mass concentration of Aβ42. They are intended to be used by in vitro diagnostics manufacturers to calibrate their diagnostic assays for Aβ42. METHODS: The three certified reference materials (CRMs), ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC, were prepared at three concentration levels and characterised using isotope dilution mass spectrometry methods. Roche, EUROIMMUN, and Fujirebio utilized the three CRMs to re-calibrate their immunoassays. RESULTS: The certified Aβ42 mass concentrations in ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC are 0.45, 0.72 and 1.22 µg/L, respectively, with expanded uncertainties (k = 2) of 0.07, 0.11 and 0.18 µg/L, respectively. Before recalibration, a good correlation (Pearson’s r > 0.97), yet large biases were observed between results from different commercial assays. After re-calibration the between assay bias was reduced to < 5 %. DISCUSSION: The Aβ42 CRMs can ensure the comparability of results between methods and across platforms for the measurement of CSF Aβ42. This may serve as the basis for the introduction of uniform cut-off levels across assays.JRC.F.6-Reference Material