Design and Development of Polysaccharide-Doxorubicin-Peptide Bioconjugates for Dual Synergistic Effects of Integrin-Targeted and Cell-Penetrating Peptides for Cancer Chemotherapy.

Polymer-drug conjugation is an attractive approach for target delivering insoluble and highly toxic drugs to tumor sites to overcome the side-effects caused by cancer chemotherapy. In this study we designed and synthesized novel polymer-drug-peptide conjugates for improved specificity on targeting cancer cells. Chemically modified polysaccharide, carboxymethylcellulose (CMC), was conjugated with doxorubicin (DOX) anticancer drug by amide bonds and dually biofunctionalized with integrin-target receptor tripeptide (RGD) and l-arginine (R) as cell-penetrating amino acid for synergistic targeting and enhancing internalization by cancer cells. These bioconjugates were tested as prodrugs against bone, breast, and brain cancer cell lines (SAOS, MCF7, and U87) and a normal cell line (HEK 293T, reference). The physicochemical characterization showed the formation of amide bonds between carboxylates (-RCOO-) from CMC biopolymer and amino groups (-NH2) from DOX and peptides (RGD or R). Moreover, these polymer-drug-peptide bioconjugates formed nanoparticulate colloidal structures and behaved as "smart" drug delivery systems (DDS) promoting remarkable reduction of the cytotoxicity toward normal cells (HEK 293T) while retaining high killing activity against cancer cells. Based on cell viability bioassays, DNA-staining, and confocal laser microscopy, this effect was assigned to the association of physicochemical aspects with the difference of the endocytic pathways and the drug release rates in live cells caused by the biofunctionalization of the macromolecule-drug systems with RGD and l-arginine. In addition, chick chorioallantoic membrane (CAM) assay was performed as an in vivo xenograft model test, which endorsed the in vitro results of anticancer activities of these polymer-drug systems. Thus, prodrug nanocarriers based on CMC-DOX-peptide bioconjugates were developed for simultaneously integrin-targeting and high killing efficacy against cancer cells, while preserving healthy cells with promising perspectives in cancer chemotherapy.