Sukru Atakan
Bilkent University, Ankara, Turkey
Title: Serum anti-tumor antibody profiling of SCLC by protein arrays has superior diagnostic power over ELISA
Biography
Biography: Sukru Atakan
Abstract
Aim- The discovery of tumor antigens capable of eliciting autologous antibody responses has not only illuminated the immunobiology of cancer but paved the way to immunotherapy protocols and commercial kits for cancer diagnosis being developed today. Screening of high density protein macro arrays is a powerful methodology to identify novel autologous antibody biomarkers. Validation of identified biomarkers with a quantifiable method like ELISA is very important for their application in clinical screenings. However, as will be explained in this talk, we find that the accuracy of protein arrays, when quantitatively evaluated, is significantly superior over ELISA. Experimental procedures- Sera obtained from fifty patients with either small cell lung cancer (SCLC), or healthy individuals were used to screen protein arrays (Source Bioscience) composed of 180 unique proteins from fetal brain, at a dilution of 1:500 and visualized using the Life Technologies’ WesternDot625® system. Proteins from selected clones were HisTag affinity purified for ELISA. ELISA results, were compared to protein array results obtained using Photoshop CS1 Histogram based quantification (PS). Sensitivity and Specificity calculations were performed using the Monte Carlo algorithm. Results- SOX2, p53 were among the 180 individual antigens and have the highest individual Sensitivity and Specificity values by all 3 types of evaluations; 1) ELISA, 2) Empirical evaluation, 3) PS. SOX2 has the following Sensitivity and Specificity values with these evaluation methods; 1) Sens: 25%, Spec: 98%, 2) Sens: 34%, Spec: 98%, 3) Sens: 43%, Spec: 98% whereas p53 has the following Sensitivity and Specificity values with these evaluation methods; 1) Sens: 16%, Spec: 98%, 2) Sens: 6%, Spec: 100%, 3) Sens: 22%, Spec: 96%. Combined evaluation of SOX2 and p53 have the following Sensitivity and Specificity values with these evaluation methods; 1) Sens: 36%, Spec: 96%, 2) Sens: 36%, Spec: 98%, 3) Sens: 82%, Spec: 90%. Discussion- Our results indicate PS method has superior sensitivity over ELISA and empirical evaluation of protein array results which depicts diagnostic value in clinical screenings. Our future perspective is to combine PS with identification and validation of new autologous antibodies to be utilized for diagnosis of SCLC and other cancers