Development of a sandwich enzyme-linked immunosorbent assay for the detection of CD44v3 using exon v3- and v6-specific monoclonal antibody pairs

Recent progress in the early detection of cancer based on CD44 biomarker; nano-biosensing approaches

CD44 is a cell matrix adhesion molecule overexpressed on the cell surfaces of the major cancers. CD44 as a cancer-related biomarker has an essential role in the invasion and metastasis of cancer. The detection and quantification of CD44 can provide essential information useful for clinical cancer diagnosis. In this regard, biosensors with sensitive and specific properties, give prominence to the development of CD44 detection platforms. To date, various aptamer-based sensitive-enhancers together with nanoparticles (NPs) have been combined into the biosensors systems to provide an innovative biosensing method (aptasensors/nano-aptasensors) with substantially improved detection limit. This review article discusses the recent advances in the field of biosensors, nanobiosensors, and aptasensors for the quantitative determination of CD44 and the detection of CD44-expressing cancer cells.

Determination of soluble CD44 in serum by using a label-free aptamer based electrochemical impedance biosensor

CD44 is a promising biomarker in the diagnosis and prognosis of malignancies. The serum CD44 level is closely related to disease progression and metastasis of malignancies. It is of great clinical significance for the detection of serum soluble CD44. In this study, a facile, label-free aptamer based electrochemical impedance sensor for serum CD44 has been proposed. The aptamer showing high affinity to CD44 was immobilized on the gold electrodes through Au-S interaction. The interaction between target CD44 and the immobilized aptamer will cause a complex structure change of the aptamer, which makes the diffusion of [Fe(CN)₆]^3-/4- toward the electrode surface easy, thus resulting in the decrease of the impedance of the system. The decreased degree of the impedance had a good linear relationship with the logarithm of the CD44 concentration in the range of 0.1-1000 ng mL^-1 with a detection limit of 0.087 ng mL^-1 (S/N = 3). The developed biosensor has been applied to detect CD44 in serum samples with satisfactory results.

CD44v6-Targeted Imaging of Head and Neck Squamous Cell Carcinoma: Antibody-Based Approaches

Head and neck squamous cell carcinoma (HNSCC) is a common and severe cancer with low survival rate in advanced stages. Noninvasive imaging of prognostic and therapeutic biomarkers could provide valuable information for planning and monitoring of the different therapy options. Thus, there is a major interest in development of new tracers towards cancer-specific molecular targets to improve diagnostic imaging and treatment. CD44v6, an oncogenic variant of the cell surface molecule CD44, is a promising molecular target since it exhibits a unique expression pattern in HNSCC and is associated with drug- and radio-resistance. In this review we summarize results from preclinical and clinical investigations of radiolabeled anti-CD44v6 antibody-based tracers: full-length antibodies, Fab, F(ab′)₂ fragments, and scFvs with particular focus on the engineering of various antibody formats and choice of radiolabel for the use as molecular imaging agents in HNSCC. We conclude that the current evidence points to CD44v6 imaging being a promising approach for providing more specific and sensitive diagnostic tools, leading to customized treatment decisions and functional diagnosis. Improved imaging tools hold promise to enable more effective treatment for head and neck cancer patients.

A Human Antibody That Binds to the Sixth Ig-Like Domain of VCAM-1 Blocks Lung Cancer Cell Migration In Vitro

Vascular cell adhesion molecule-1 (VCAM-1) is closely associated with tumor progression and metastasis. However, the relevance and role of VCAM-1 in lung cancer have not been clearly elucidated. In this study, we found that VCAM-1 was highly overexpressed in lung cancer tissue compared with that of normal lung tissue, and high VCAM-1 expression correlated with poor survival in lung cancer patients. VCAM-1 knockdown reduced migration of A549 human lung cancer cells into Matrigel, and competitive blocking experiments targeting the Ig-like domain 6 of VCAM-1 (VCAM-1-D6) demonstrated that the VCAM-1-D6 domain was critical for VCAM-1 mediated A549 cell migration into Matrigel. Next, we developed a human monoclonal antibody specific to human and mouse VCAM-1-D6 (VCAM-1-D6 huMab), which was isolated from a human synthetic antibody library using phage display technology. Finally, we showed that VCAM-1-D6 huMab had a nanomolar affinity for VCAM-1-D6 and that it potently suppressed the migration of A549 and NCI-H1299 lung cancer cell lines into Matrigel. Taken together, these results suggest that VCAM-1-D6 is a key domain for regulating VCAM-1-mediated lung cancer invasion and that our newly developed VCAM-1-D6 huMab will be a useful tool for inhibiting VCAM-1-expressing lung cancer cell invasion.