Identification of Tumor-associated Autoantigens for the Diagnosis of Colorectal Cancer in Serum Using High Density Protein Microarrays

Ingrid Babel,Rodrigo Barderas,Ramón Díaz-Uriarte,Jorge Luis Martínez-Torrecuadrada,Marta Sánchez-Carbayo,J Ignacio Casal

doi:10.1074/mcp.m800596-mcp200

Abstract

There is a mounting evidence of the existence of autoantibodies associated to cancer progression. Antibodies are the target of choice for serum screening because of their stability and suitability for sensitive immunoassays. By using commercial protein microarrays containing 8000 human proteins, we examined 20 sera from colorectal cancer (CRC) patients and healthy subjects to identify autoantibody patterns and associated antigens. Forty-three proteins were differentially recognized by tumoral and reference sera (p value <0.04) in the protein microarrays. Five immunoreactive antigens, PIM1, MAPKAPK3, STK4, SRC, and FGFR4, showed the highest prevalence in cancer samples, whereas ACVR2B was more abundant in normal sera. Three of them, PIM1, MAPKAPK3, and ACVR2B, were used for further validation. A significant increase in the expression level of these antigens on CRC cell lines and colonic mucosa was confirmed by immunoblotting and immunohistochemistry on tissue microarrays. A diagnostic ELISA based on the combination of MAPKAPK3 and ACVR2B proteins yielded specificity and sensitivity values of 73.9 and 83.3% (area under the curve, 0.85), respectively, for CRC discrimination after using an independent sample set containing 94 sera representative of different stages of progression and control subjects. In summary, these studies confirmed the presence of specific autoantibodies for CRC and revealed new individual markers of disease (PIM1, MAPKAPK3, and ACVR2B) with the potential to diagnose CRC with higher specificity and sensitivity than previously reported serum biomarkers.

Highlights

There is a mounting evidence of the existence of autoantibodies associated to cancer progression
PIM1, MAPKAPK3, and ACVR2B as Biomarkers for Colorectal Cancer Screening—We developed an ELISA test to study the ability of PIM1, MAPKAPK3, and ACVR2B to discriminate between diseased individuals and reference sub
We found for ACVR2B a specificity and a sensitivity of 76.2 and 60%, respectively and an area under the curve of 0.66

Summary

Introduction

There is a mounting evidence of the existence of autoantibodies associated to cancer progression. A diagnostic ELISA based on the combination of MAPKAPK3 and ACVR2B proteins yielded specificity and sensitivity values of 73.9 and 83.3% (area under the curve, 0.85), respectively, for CRC discrimination after using an independent sample set containing 94 sera representative of different stages of progression and control subjects. These studies confirmed the presence of specific autoantibodies for CRC and revealed new individual markers of disease (PIM1, MAPKAPK3, and ACVR2B) with the potential to diagnose CRC with higher specificity and sensitivity than previously reported serum biomarkers. The abbreviations used are: CRC, colorectal cancer; CEA, carcinoembryonic antigen; TAA, tumor-associated autoantigen; TMA, tissue microarray; CI, confidence interval; ROC, receiver operating characteristic; AUC, area under the curve; MAPKAPK, mitogen-activated protein kinase-activated protein kinase; ERK, extracellular signalregulated kinase

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