In-vitro Efficacy and Intracellular Mechanism of Riboflavin-Conjugated PEGylated Poly- L-Lysine Dendrimer

Abstract

Chemotherapeutic drugs have advanced using different drug delivery methods to treat breast cancer specifically. This development has arisen because many classical drugs exhibit physicochemical limitations including solubility, specificity, stability, biodistribution, and therapeutic efficacy. There were numerous adverse effects associated with these limitations because chemotherapeutic drugs enter normal tissues. In order to eliminate off-target side-effect,nanoparticles were developed to target anticancer drugs to a specific carcinogenic area. As one of developing nanomedicines, dendrimers possess ability to be utilized in different administration routes and has potential to stay in the blood circulation longer while showing increased accumulation in tumor cells. Commercially available poly (amidoamine) (PAMAM) dendrimers have the potential to cause toxicity in vivo due to lack of biodegradation at sites of accumulation. Poly-L-Lysine (PLL) dendrimers are an alternative class of dendrimers that possess a biodegradable structure. PEGylated poly-l-lysine (PLL) dendrimers are known to be more favorable due to lessened cytotoxicity manifested by masking of cationic charges and avoiding uptake by Reticulo Endothelial System (RES). Using this biodegradable dendrimer, we sought to examine the effect of PEGylation as well as delivering anti-cancer drug, Doxorubicin (DOX), to a targeted internalization pathway in human breast cancer cells effectively. PEGylated PLL dendrimers also have their limitation, in which some tumor cells are not dependent upon enhanced permeability and retention (EPR) effect. As a result, riboflavin receptor, which is found to be upregulated in the exterior of breast and ovarian cancer cells, was utilized by attaching a riboflavin ligand to PEGylated PLL dendrimers in order to be actively uptaken by breast cancer cells. To target chemotherapeutic drug selectively and efficaciously, riboflavin conjugated PLL dendrimers were assessed in-vitro by investigating cytotoxicity, uptake accumulation, and intracellular colocalization. Further investigation on the endocytosis mechanism and detailed intracellular trafficking in different compartments of the cells were analyzed in order to fully understand the machinery behind delivering chemotherapeutic drugs successfully.