Detection of alpha-methylacyl-CoA racemase (AMACR), a biomarker of prostate cancer, in patient blood samples using a nanoparticle electrochemical biosensor.

Matthew M Cooney,Anna C Samia,Chung-Chiun Liu,James D Mcguffin-Cawley,Sanjay Gupta,Cheryl L Thompson,Kai-Lun Cheng,Fuh-Sheng Shieu,Po-Yuan Lin

doi:10.1200/jco.2012.30.30_suppl.41

Abstract

41 Background: A promising prostate cancer biomarker, alpha-methylacyl-CoA racemase (AMACR), has demonstrated the ability to distinguish cancer from healthy and benign cells with high sensitivity and specificity. However the lack of a good clinical assay has limited its translation into the clinic. Here we report on the development of a single use disposable biosensor for AMACR detection. Methods: This is a very inexpensive, small, single-use disposable sensor that requires only a drop of plasma and connects to a portable device. The biosensor utilizes the reaction of pristanic acid with a substrate that includes AMACR to produce Trans-2,3-dehydropritanayl-CoA plus H2O2. The biosensor utilizes iridium oxide nanoparticle catalyst to oxidize the H2O2 produced in the above metabolic pathway. Thus the oxidation of H2O2 yields a measurable current to quantify AMACR in the sample. This is the first in vitro assay method for AMACR based on this reaction mechanism. Results: In our study including plasma from 9 healthy males, 10 patients with high grade prostatic intraepithelial neoplasia and 5 prostate cancer patients we show 100% accuracy in separating prostate cancer patients from controls as well as those with benign prostate conditions. Conclusions: Our data provides strong evidence for the ability of this biosensor to perform as a reliable assay for prostate cancer detection and diagnosis.

Highlights

Prostate cancer is the most common malignancy among men in the United States and ranks as the second most common cause of cancer death in males [1]
We expected that the level of alpha-methylacyl-coenzyme A (CoA) racemase (AMACR) would increase in prostate cancer patients
In order to evaluate this assessment, plasma samples from 9 healthy males, 10 men with high grade prostatic neoplasia (HGPIN) and 5 men with prostate cancers were used in a laboratory-blinded test of the AMACR levels in these samples. 5mL of blood was collected from each patient in standard heparinized tubes

Summary

Introduction

Prostate cancer is the most common malignancy among men in the United States and ranks as the second most common cause of cancer death in males [1]. Many of the men diagnosed with prostate cancers have clinically insignificant disease, which will never become symptomatic in their lifetime This ―over-diagnosis‖ of clinically insignificant prostate cancer from PSA screening has been estimated to be as high as 30%. In a previous study sera from men with biopsy-proven prostate cancer and men without known prostate cancer have been screened for a humoral immune response to AMACR [8]. This study concludes that AMACR immune-reactivity is statistically significantly higher in the sera from cancer case subjects than from the control subjects These studies suggest that if a reliable method for the detection of AMACR from blood or urine can be established, it will be able to identify men with prostate cancer and may be able to serve as a reliable biomarker for prostate cancer. 100% accuracy, between both healthy men, men with high grade prostatic intraepithelial neoplasia, and men with biopsy proven prostate cancer

Chemistry and Reaction Mechanisms of Detecting AMACR

AMACR Biosensor Fabrication

Calibration of this AMACR Biosensor

Results and Discussion

Conclusions