SELEX aptamer used as a probe to detect circulating tumor cells in peripheral blood of pancreatic cancer patients.

Jinqiang Zhang,Lanping Zhou,Ningsheng Shao,Fang Liu,Shaohua Li,Xiaohang Zhao,Natasha Kyprianou

doi:10.1371/journal.pone.0121920

Jinqiang Zhang, Lanping Zhou + Show 5 more

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https://doi.org/10.1371/journal.pone.0121920

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Abstract

Many studies have shown that the quantity and dynamics of circulating tumor cells (CTCs) in peripheral blood of patients afflicted with solid tumours have great relevance in therapeutic efficacy and prognosis. Different methods based on various strategies have been developed to isolate and identify CTCs, but their efficacy needs to be improved because of the rarity and complexity of CTCs. This study was designed to examine the possibility of using a SELEX aptamer (BC-15) as a probe to identify rare CTCs out of background nucleated cells. Aptamer BC-15 was selected from a random oligonucleotide library screened against human breast cancer tissue. Fluorescence staining showed that BC-15 had a high affinity for nuclei of human cancer cell lines of various origins as well as CTCs isolated from pancreatic cancer patients, whereas its binding capacity for non-tumor breast epithelial cells and leukocytes was almost undetectable. BC-15+/CD45- cells in cancer patient blood were also found to be cytokeratins 18-positive and aneuploid by immunofluorescence staining and fluorescent in situ hybridization, respectively. Finally, the aptamer method was compared with the well-established anti-cytokeratin method using 15 pancreatic cancer patient blood samples, and enumeration indicated no difference between these two methods. Our study establishes a novel way to identify CTCs by using a synthetic aptamer probe. This new approach is comparable with the anti-cytokeratin-based CTC identification method.

Highlights

Circulating tumor cells (CTCs) have been found in the peripheral blood of patients afflicted with all major solid carcinomas[1] and their quantity and fluctuation in cancer patient blood correlated with tumor development, therapeutic efficacy, tumor recurrence, and long-term prognosis[2,3,4]
BC-15 binds to the nucleus of human tumor cells
Our previous study shows that BC-15 can bind to breast cancer cells and tissues with high affinity, whereas its binding capacity for non-tumorigenic cells and normal breast tissues is much lower; in addition to fluorescence staining, flow cytometric confirmed that BC-15 has a high affinity for tumor cells [12]

Summary

Introduction

Circulating tumor cells (CTCs) have been found in the peripheral blood of patients afflicted with all major solid carcinomas[1] and their quantity and fluctuation in cancer patient blood correlated with tumor development, therapeutic efficacy, tumor recurrence, and long-term prognosis[2,3,4]. CTC detection provides a possible way to monitor patient response to certain anti-cancer therapies[5, 6]. Many techniques have been developed to identify CTCs in patients with different types of cancer[7]. Detecting CTCs by Aptamer epithelial origin of CTCs to capture and identify them using antibodies that target epithelial markers such as epithelial cellular adhesion molecule (EpCAM) and cytokeratin (CK)[2]. Some CTCs may lose their epithelial characteristics because of the epithelia-mesenchymal transition (EMT) and cannot be detected by these antibodies[8]. These methods have difficulty discriminating malignant cells from benign cells that express epithelial markers. The development of novel and more effective approaches for CTCs detection is urgently needed

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