Aiming to improve the performance of a nanoparticle formulation of the drug doxorubicin, the investigators decided to target a cell surface protein known as the transferrin receptor, which is involved in satisfying cellular demands for iron. To determine if this receptor was a suitable target, the researchers first quantified levels of the transferrin receptor on malignant and healthy lung epithelial cells. Their results showed clearly that malignant cells possessed far higher levels of this protein than did their healthy counterparts.
Next, the investigators prepared lipid-based, doxorubicin-loaded nanoparticles decorated with the molecule transferrin. When they compared cell uptake of these targeted nanoparticles with that of nanoparticles lacking transferrin, the researchers found that uptake of the targeted nanoparticles was far greater. More importantly, the targeted nanoparticles were far more toxic to malignant cells than were the untargeted nanoparticles. In addition, the targeted nanoparticles were more toxic to malignant cells than they were to healthy cells, suggesting that targeting the transferrin receptor could prove to be an effective means of improving the ability of anticancer nanoparticles to deliver drug specifically to tumor cells.