An Exonuclease III Protection-Based Electrochemical Method for Estrogen Receptor Assay

Sha Zhu,Genxi Li,Yongmei Yin,Ya Cao,Yuanyuan Xu

doi:10.3390/ijms140510298

Abstract

Estrogen receptor (ER), expressed in approximately 80% of primary breast cancer cells, has proven to be a valuable predictive factor of the disease. Herein, by making use of the specific binding of ER to its DNA response elements, we propose an Exonuclease III (Exo III) protection-based electrochemical method for detecting ER proteins. In this assay, the presence of ER can protect the duplex DNA molecules immobilized on an electrode surface from Exo III-catalyzed digestion, resulting in an increased electrochemical signal. Experimental results have revealed that the proposed method can allow the quantification of ER in the range of 0.5 to 100 nM with a satisfactory detection limit of 0.38 nM. Furthermore, since this approach can also be employed to detect ER directly in nuclear extracts, it may be of great use in biomedical applications in the future.

Highlights

Estrogen receptor (ER), a ligand-dependent transcription factor, is a member of the nuclear hormone receptor superfamily [1,2]
The biological effects of ER are mediated by its binding to estrogen, and are involved in activating transcription either by direct binding to its own DNA response elements or by tethering to other transcription factors [3,4]
P1 is thiolated to ensure self-assembly on the gold electrode surface, while P2 is modified with methylene blue (MB) to serve as an electroactive signaling probe

Summary

Introduction

Estrogen receptor (ER), a ligand-dependent transcription factor, is a member of the nuclear hormone receptor superfamily [1,2]. The biological effects of ER are mediated by its binding to estrogen, and are involved in activating transcription either by direct binding to its own DNA response elements (estrogen response elements, EREs) or by tethering to other transcription factors [3,4]. Emerging findings suggest that ER plays an important role in the biology of breast cancer [5,6]. ER has been regarded as a valuable marker or target for the diagnosis of breast cancer, and the study to develop new methods for ER assay has attracted increasing interest so as to monitor the related pathological or therapeutical phenomena

Methods

Results

Conclusion