Noninvasively characterizing the different alphavbeta3 expression patterns in lung cancers with RGD-USPIO using a clinical 3.0T MR scanner.

The adhesion molecule alphavbeta3 integrin plays an important role in tumor development and metastases. We demonstrated the specificity of the probe to alphavbeta3 integrin with transmission electron microcopy (TEM) and magnetic resonance imaging (MRI). The in vivo targeting behavior of the probe was examined in 2 tumor models with different alphavbeta3 expression patterns by a 3.0T MRI scanner. MR imaging showed that R2* pseudo-color pictures of A549 lung cancer tumor was different from that of 3LL lung cancer. For A549 tumor, an homogeneous decrease of signal intensity was observed throughout the tumor, which was more evident in the periphery or central areas. Histological studies revealed that alphavbeta3 integrin was expressed both on the tumor vessel and tumor cells for A549 tumor. Our findings indicated that it was possible to noninvasively characterize the different alphavbeta3 expression pattern in lung cancers with arginine-glycine-aspartic acid (RGD) peptide conjugated ultra-small superparamagnetic iron oxide nanoparticles (RGD-USPIO) using a clinical 3.0T MR scanner. Nevertheless, the way of imaging targeting presentation of the probe differed in tumors with different alphavbeta3 expression patterns.