Preclinical Assessment of Paclitaxel- and Trastuzumab-Delivering Magnetic Nanoparticles FeO for Treatment and Imaging of HER2-Positive Breast Cancer.

The purpose of this study was to investigate the anticancer activity and the potential imaging use of the innovative combination of magnetic nanoparticles (MNPs)-FeO, paclitaxel (PTX), and trastuzumab (Herceptin) in HER2-positive breast cancer. MNPs-FeO was synthesized and underwent water phase transfer and hydrophobic molecular loading, and its surface was then coupled with Herceptin mono-antibody. The morphological characteristics of MNPs-FeO were observed under transmission electron microscopy (TEM). Effects of PTX-Herceptin-MNPs-FeO on breast cancer cells were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,4-diphenyltetrazolium bromide assay and the flow cytometric apoptosis assay. To establish a xenograft model, we injected breast cancer SK-BR-3 cells into the left thighs of nude mice. We measured the effect of PTX-Herceptin-MNPs-FeO on tumor growth by measuring tumor size and calculating inhibition rate with immunohistochemistry analysis further performed, and analyzed MNPs-FeO accumulation in tumor lesions using magnetic resonance imaging and fluorescence imaging. Most MNPs were in spherical shape of about 10 nm in diameter observed under TEM. PTX-Herceptin-MNPs-FeO showed greater cytotoxic effects, and induced a higher apoptosis rate of SK-BR-3 cells than all the other groups, with corresponding changes of apoptosis-related proteins. Meanwhile, the tumor xenograft model showed that tumor inhibition rate in the PTX-Herceptin-MNPs-FeO group was higher than in the PTX-Herceptin group. Furthermore, PTX-Herceptin-MNPs-FeO enhanced the T2 imaging contrast enhancement effect on tumors in tumor-bearing mice. The novel PTX-Herceptin-MNPs-FeO combination may represent a promising alternative breast cancer treatment strategy and may facilitate tumor imaging.