Integrin αvβ6-targeted MR molecular imaging of breast cancer in a xenograft mouse model

Abstract

Background The motif RXDLXXL-based nanoprobes allow specific imaging of integrin αvβ6, a protein overexpressed during tumorigenesis and tumor progression of various tumors. We applied a novel RXDLXXL-coupled cyclic arginine-glycine-aspartate (RGD) nonapeptide conjugated with ultrasmall superparamagnetic iron oxide nanoparticles (referred to as cFK-9-USPIO) for the application of integrin αvβ6-targeted magnetic resonance (MR) molecular imaging for breast cancer. Methods A novel MR-targeted nanoprobe, cFK-9-USPIO, was synthesized by conjugating integrin αvβ6-targeted peptide cFK-9 to N-amino (−NH2)-modified USPIO nanoparticles via a dehydration esterification reaction. Integrin αvβ6-positive mouse breast cancer (4 T1) and integrin αvβ6 negative human embryonic kidney 293 (HEK293) cell lines were incubated with cFK-9-AbFlour 647 (blocking group) or cFK-9-USPIO (experimental group), and subsequently imaged using laser scanning confocal microscopy (LSCM) and 3.0 Tesla magnetic resonance imaging (MRI) system. The affinity of cFK-9 targeting αvβ6 was analyzed by calculating the mean fluorescent intensity in cells, and the nanoparticle targeting effect was measured by the reduction of T2 values in an in vitro MRI. The in vivo MRI capability of cFK-9-USPIO was investigated in 4 T1 xenograft mouse models. Binding of the targeted nanoparticles to αvβ6-positive 4 T1 tumors was determined by ex vivo histopathology. Results In vitro laser scanning confocal microscopy (LSCM) imaging showed that the difference in fluorescence intensity between the targeting and blocking groups of 4 T1 cells was significantly greater than that in HEK293 cells (P < 0.05). The in vitro MRI demonstrated a more remarkable T2 reduction in 4 T1 cells than in HEK293 cells (P < 0.001). The in vivo MRI of 4 T1 xenograft tumor-bearing nude mice showed significant T2 reduction in tumors compared to controls. Prussian blue staining further confirmed that αvβ6 integrin-targeted nanoparticles were specifically accumulated in 4 T1 tumors and notably fewer nanoparticles were detected in 4 T1 tumors of mice injected with control USPIO and HEK293 tumors of mice administered cFK-9-USPIO. Conclusions Integrin αvβ6-targeted nanoparticles have great potential for use in the detection of αvβ6-overexpressed breast cancer with MR molecular imaging.

Nano-Based Theranostic Platforms for Breast Cancer: A Review of Latest Advancements

“…Prussian blue staining provided additional confirmation that v6 integrin-targeted NPs had specifically accumulated in 4T1 BC cells. Comparatively, significantly fewer particles were seen in the 4 T1 tumors of mice that had been injected with control USPIO [ 120 ]. We believe that these findings provided solid evidence for the usage of integrin v6-targeted NPs to be applied in magnetic resonance molecular imaging and help target v6-overexpressed BC cells.…”

Multifunctional PD-L1 Targeted Fe3O4@DOX Nanoparticles Under MRI Monitoring For Combination Therapy of Triple-Negative Breast Cancer

“…The cellular uptake of nanoparticles was evaluated by prussian blue staining, which was used to detect the presence of iron element, following the procedures reported previously [27]. The cells were observed under a light microscope to determine the intracellular distribution of nanoparticles.…”

Automated Synthesis and Preclinical Evaluation of Optimized Integrin α6-Targeted Positron Emission Tomography Imaging of Pancreatic Cancer

“…Several PET tracers, such as arginine-glycine-aspartic (RGD) derivatives targeted-integrin αvβ3 receptors, have been involved in clinical trials and have shown good application value in many types of solid tumors. − As a subtype of the integrin family, integrin α6 is expressed on the surface of the cells and acts as a regulator of a variety of cellular functions that are critical to the occurrence, development, and metastasis of solid tumors . Various researchers have reported the potential clinical application value of integrin α6 in many tumor models including for hepatocellular carcinoma (HCC), breast cancer, lung cancer, and colorectal cancer . Richard H. Kimura et al developed an integrin αvβ6 cystine knot PET tracer that can effectively detect multiple cancers in different parts of the body .…”

“…Previously, we identified an integrin α6-targeted peptide CRWYDENAC (dubbed RWY) using phage display technology . The current peptide RWY has been translated into an integrin α6-targeted PET tracer and MRI tracer that have been successfully applied for tumor imaging of the integrin α6 expression, ,, However, the binding affinity of RWY to the integrin α6 protein (micromolar affinity) still needs to be improved. In this work, we identified an optimized RWY dimer designated as RD2 (nanomolar affinity) by using an alanine scan strategy to enhance the pharmacokinetics, tumor-targeting efficacy, and in vivo imaging of the RWY tracer.…”