The Presence of Anti-GRP78 Antibodies in the Serum of Patients with Colorectal Carcinoma: A Potential Biomarker for Early Cancer Detection

Abstract

Background The identification of new biomarkers is required for early diagnosis of colorectal carcinoma patients (CRC), since about 20% of these patients are initially diagnosed with a distant metastatic disease. GRP78, a heat shock protein, functions also as a cell surface signaling receptor of cells under physiological stress. GRP78 was found to be expressed on the cell surface of various tumor cells. The presence of autoantibodies to GRP78 in cancer patient's serum was found to be correlated with a poor prognosis. In this study we aimed to identify anti-GRP78 antibodies in the serum of 85 patients diagnosed by colonoscopy, as an early detection biomarker. Methods We developed an ELISA assay with recombinant GRP78 immobilized on 96-well culture plates and used an anti-IgG antibody to measure the sole anti-GRP78 IgGs. Results Testing for anti-GRP78 showed a significant increase in antibody titer in patients with a polyp and in CRC patients (p<0.001) compared to healthy subjects. Conclusions This is the first study showing the presence of anti-GRP78 at the very early stages of CRC.