Characterizing Breast Cancer Xenograft Epidermal Growth Factor Receptor Expression by Using Near-Infrared Optical Imaging

Abstract

Background-Epidermal growth factor receptor (EGFR) overexpression is associated with several key features of cancer development and growth. Therefore, EGFR is a very promising biological target for tumor diagnosis and anticancer therapy. Characterization of EGFR expression is important for clinicians to select patients for EGFR-targeted therapy and evaluate therapeutic effects. Purpose-To investigate whether near-infrared (NIR) fluorescent dye Cy5.5-labeled anti-EGFR monoclonal antibody Erbitux can characterize EGFR expression level in MDA-MB-231 and MCF-7 breast cancer xenografts using an in vivo NIR imaging method. Material and Methods-A fluorochrome probe was designed by coupling Cy5.5 to Erbitux through acidylation, and the fluorescence property of the Erbitux-Cy5.5 conjugate was characterized by fluorospectroscopy. Flow cytometry and laser confocal microscopy were used to test the EGFR specificity of the antibody probe in vitro. Erbitux-Cy5.5 was also injected intravenously into immune-deficient mice bearing MDA-MB-231 or MCF-7 tumors. Whole-body and region-of-interest fluorescence images were acquired and analyzed. The EGFR expression was also analyzed and confirmed by immunohistochemical assay. Results-The maximum excitation/emission wavelength for the Erbitux-Cy5.5 probe was 674/697 nm, similar to that of free Cy5.5 (674/712 nm). Confocal microscopy confirmed receptorspecific uptake in MDA-MB-231 and MCF-7 cells. In flow cytometry probe specificity assay, Erbitux-Cy5.5 showed a 9.32-fold higher affinity for MDA-MB-231 than MCF-7 cells. In vivo NIR imaging also indicated specific uptake in EGFR-positive tumors. Probe uptake rate and maximum intake dose in MDA-MB-231 were significantly higher than those in MCF-7 xenografts (P < 0.001). Immunohistochemical staining confirmed the in vivo imaging results, showing differentiated EGFR expression in MDA-MB-231 (+ + +) and MCF-7 (+) tumor tissues. Conclusion-Erbitux-Cy5.5 may be used as a specific NIR contrast agent for the noninvasive characterization of EGFR expression level in breast cancer xenografts.

Systems Molecular Imaging: Right Around the Corner

“…For the EGFR signaling pathway, researchers used Cy5.5 to label modified hEGF, a natural ligand for EGFR. The synthetic EGF-Cy5.5 probe can target and visualize EGFR receptor extracellular binding domains [18][19][20]. Other investigators used radionuclide fluorine-18 or I-125 to labeled EGFR receptor tyrosine kinase inhibitor to target and image the mutated EGFR intracellular tyrosine activation domain [21,22].…”

Statins anticancer targeted delivery systems: re-purposing an old molecule

“…The cytotoxicity of TRF/SV in parenteral lipid nanoemulsion was evaluated on both MCF‐7 and MDA‐MB‐231 cells. MDA cell lines were more sensitive to TRF than MCF since MDA showed greater overexpression of the epidermal growth factor receptor (EGFR) and protein kinase C (PKC) that represented the two main targets for TRF . The date in Table reveals that TRF/SV lipid nanoemulsion scored IC50 (μ m ) of = 10.3 and 4.9 on MCF7 and MDA 231, respectively compared with TRF nanoemulsion alone (IC50 = 14 and 7 on MCF7 and MDA 231 respectively) and SV solution alone (IC50 = 19 and 8 on MCF and MDA 231 respectively).…”

Translational Research of Optical Molecular Imaging for Personalized Medicine

“…For example, for a drug being developed against an EGFR, which is a transmembrane glycoprotein composed of a single polypeptide chain, an imaging probe that directly binds to EGFR (for example, Cy5.5-Erbitux in fluorescence imaging) can be used for assessing target expression. Chen's group used Erbitux-Cy5.5 to demonstrate the EGFR expression level in breast cancer xenografts [59]. His group used Cy5.5-conjugated GX1 peptide in a subcutaneous U87MG glioblastoma xenograft model to investigate tumor-targeting efficacy and the results suggested that Cy5.5-GX1 was a promising molecular probe for optical imaging of tumor vasculature [60], and the imaging results are shown in Fig.…”