A Magnetic Bead-Based Sensor for the Quantification of Multiple Prostate Cancer Biomarkers

Jesse V Jokerst,James D Brooks,Zuxiong Chen,Lingyun Xu,Breeana Mitchell,Edwin Chang,Sanjiv S Gambhir,Rosalie Nolley,Chandan Kumar-Sinha

doi:10.1371/journal.pone.0139484

Abstract

Novel biomarker assays and upgraded analytical tools are urgently needed to accurately discriminate benign prostatic hypertrophy (BPH) from prostate cancer (CaP). To address this unmet clinical need, we report a piezeoelectric/magnetic bead-based assay to quantitate prostate specific antigen (PSA; free and total), prostatic acid phosphatase, carbonic anhydrase 1 (CA1), osteonectin, IL-6 soluble receptor (IL-6sr), and spondin-2. We used the sensor to measure these seven proteins in serum samples from 120 benign prostate hypertrophy patients and 100 Gleason score 6 and 7 CaP using serum samples previously collected and banked. The results were analyzed with receiver operator characteristic curve analysis. There were significant differences between BPH and CaP patients in the PSA, CA1, and spondin-2 assays. The highest AUC discrimination was achieved with a spondin-2 OR free/total PSA operation—the area under the curve was 0.84 with a p value below 10−6. Some of these data seem to contradict previous reports and highlight the importance of sample selection and proper assay building in the development of biomarker measurement schemes. This bead-based system offers important advantages in assay building including low cost, high throughput, and rapid identification of an optimal matched antibody pair.

Highlights

Prostate cancer (CaP) is the second leading cause of cancer death in US men, yet effective screening and prognostication tools have remained elusive due to non-specific assays and biomarkers [1]
FPSA: The c.Ab (Meridian p/n M86806M) the d.Ab (Meridian p/n M66276M) were both mouse monoclonal IgG. For both total PSA (tPSA) and free PSA (fPSA) we used native human prostate specific antigen (PSA) prepared in our laboratory as the standard [34]
In comparing Gleason 7 patients versus benign prostatic hypertrophy (BPH) with IL-6 soluble receptor (IL-6sr), we found an AUC value of 0.66; the 95% confidence interval was 0.57 to 0.76 with p = 0.005

Summary

Introduction

Prostate cancer (CaP) is the second leading cause of cancer death in US men, yet effective screening and prognostication tools have remained elusive due to non-specific assays and biomarkers [1]. While enzyme-linked immunosorbent assay (ELISA) is the gold standard for measuring serum proteins, it suffers from long assay development times for new biomarkers, high. ELISA can suffer from high background and non-specific interferences because it uses an optical-based reporting scheme. Many competing technologies have been proposed including chemiluminescent-, microfluidic- [2], nanotechnology- [3], and magnetic-based [4] approaches. Many of these approaches suffer from high cost, low throughput, long assay construction times, and the need for a skilled operator. The biomarker community would be well served by analytical tools for panels of biomarkers

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