Assembly of prednimustine low-density-lipoprotein complexes and their cytotoxic activity in tissue culture.

The lipophilic anticancer drug prednimustine was incorporated into model low-density-lipoprotein (m-LDL) using a novel modified method. The major steps of this procedure involve the preparation of a microemulsion containing the drug and the complexing of this emulsion with apolipoprotein B (apo B) that has been delipidated by heptane extraction. The resulting particles contained on average 338 mol prednimustine/mol apoB and exhibited a diameter that was ca. 2.5 times that of native LDL. The cellular binding, uptake, and metabolism of the complexes were found to be similar to those of native LDL. The cytotoxic activity of the complexes was monitored in vitro against T-47D breast cancer cells and normal 3T3 fibroblasts. The activity of prednimustine in m-LDL against T-47D cells after 24 h treatment was nearly 50% higher than that of the free drug, whereas in 3T3 cells the difference was relatively small. The results indicate that it is possible to target drug/m-LDL complexes to cancer cells exhibiting high LDL-receptor activity.