Noncatalytic Endosialidase Enables Surface Capture of Small-Cell Lung Cancer Cells Utilizing Strong Dendrimer-Mediated Enzyme-Glycoprotein Interactions

Abstract

Enumeration of circulating tumor cells (CTCs) of small-cell lung cancer (SCLC) patients has been shown to predict the disease progress and long-term survival. Most CTC detection methods rely on epithelial surface markers, such as epithelial cell adhesion molecule (EpCAM). However, this marker in SCLC is reported to be often downregulated after a variety of phenotypic changes, which impairs the reliability of EpCAM-based CTC detections. In this regard, the development of an alternative CTC detection method involving different CTC surface markers is in demand. In this study, we evaluated, for the first time to our knowledge, the feasibility of detecting SCLC CTCs using a noncatalytic endosialidase (EndoN Trap, EndoNt). This noncatalytic enzyme was chosen due to its high affinity to polysialic acid (polySia), a cell-surface glycan, that is highly expressed by SCLC tissue. Furthermore, this enzyme-based system was integrated into our dendrimer-mediated CTC capture platform to further enhance the capture efficiency via multivalent binding. We found that the EndoNt-immobilized surfaces could specifically capture polySia-positive SCLC cells and the binding between SCLC cells and EndoNt surfaces was further stabilized by dendrimer-mediated multivalent binding. When compared to the EpCAM-based capture, EndoNt significantly improved the capture efficiency of polySia-positive SCLC cells under flow due to its higher binding affinity (lower dissociation rate constants). These findings suggest that this enzyme-based CTC capture strategy has the potential to be used as a superior alternative to the commonly used EpCAM-based methods, particularly for those types of cancer that overexpress polySia.

Multivalency Interface and g-C3N4 Coated Liquid Metal Nanoprobe Signal Amplification for Sensitive Electrogenerated Chemiluminescence Detection of Exosomes and Their Surface Proteins

“…24,25 The capture efficiency of cells was enhanced via dendrimer-mediated circulating tumor cells capture platform. 26 In recent years, the multivalency strategies have been also executed on AuNPs, graphene for carbohydrate, antibody, and aptamers. 27−29 The binding affinity can be significantly improved by "cluster effect" of the molecules on nanoscaffolds.…”

“…The multivalent system has been proven to overcome the low affinity with 1–9 orders of magnitude relative to monovalent binding on the basis of special scaffolds. For instance, the valid way of organizing a multivalent array was provided by the dendritic scaffold with their inherent repetitive branched structures. , Poly­(amidoamine) (PAMAM) dendrimers, a new polymer with well-defined globular shape, branched treelike structure, and amounts of functional groups on its periphery, have been applied in facilitating multivalent effects. , The capture efficiency of cells was enhanced via dendrimer-mediated circulating tumor cells capture platform . In recent years, the multivalency strategies have been also executed on AuNPs, graphene for carbohydrate, antibody, and aptamers. − The binding affinity can be significantly improved by “cluster effect” of the molecules on nanoscaffolds.…”

Advances in isolation and detection of circulating tumor cells based on microfluidics

“…Hsu et al 68 proposed a noncatalytic endosialidase as a biomarker, which has high affinity to polysialic acid and is a cell-surface glycan that is highly expressed small cell lung cancer (SCLC) tissue. This enzyme-based system further enhances the capture efficiency via multivalent binding compared to their EpCAM counterparts.…”

Recent advances in development of dendritic polymer‐based nanomedicines for cancer diagnosis

“…In contrast to the G7/aEpCAM group, the G7/EndoNt group demonstrated a much higher capture efficiency of NCI-H69 and SW-2 cells (about 2.5 and 1.8 times, respectively). Due to multivalent binding of dendrimers, the G7 dendrimer-modified group exhibited a reduced dissociation rate constant compared to that of the PEG-modified control (Hsu et al, 2018). In another report, Hong et al developed a G7 dendrimer-based platform to capture EMTCTCs that had become invasive and metastatic, and escaped from the capture through a common EpCAM-targeted platform (Figure 6a).…”