Establishment of an in vitro model expressing the folate receptor for the investigation of targeted delivery systems

In the last ten years folate targeting has emerged as one of the most promising approach in specific drug targeting towards solid tumors. Despite this growing interest, some of the cellular models generally used to investigate folate-targeted drug carriers lack accurate characterization. Furthermore, because of the variability of the folate receptor expression in vivo, it should be important to evaluate the carriers in a situation of increasing expression levels. The aim of this note is to present an in vitro model, consisting of three different cell lines (HeLa, KB 3-1 and MCF7 cells), in which the conditions leading to a reliable and constant over-expression of the folate receptor have been determined and the quantity of receptor present at the surface of the cells quantified. The selected cell lines express various amounts of the protein, from a non-detectable level in MCF7 cells to a high level of over-expression rate in KB cells, resulting in an interesting range of conditions useful for the investigation of folate-targeted vectors.