[Chrono-drug delivery system based on the circadian rhythm of transferrin receptor].

Transferrin receptor 1(TfR1) is a key cell surface molecule that regulates the uptake of iron-bound transferrin. TfR1 expression is higher in tumor cells than in normal cells. Thus, intracellular targeting using iron-saturated Tf as a ligand for TfR-mediated endocytosis has attracted attention. TfR1 in colon cancer-bearing mice exhibits a 24-hour rhythm in mRNA and protein levels. The clock-controlled gene c-MYC rhythmically activate the transcription of the TfR1 gene. In addition, the cyclical accumulation of TfR1 causes dosing time-dependent changes in the intratumoral delivery of drug by receptor-mediated endocytosis. Identification of the circadian properties of molecules that are targeted by ligand-directed DDS may aid the choice of the most appropriate time of day for their administration.