Chemically Conjugating Poty(Amidoamine) With Chondroitin Sulfate To Treat CD44Positive Tumor Through The MiR-34a Delivery

Therapeutic strategies based on the modulation of microRNA activity possessmuch promise in cancer gene therapy. MicroRNA-34a (miR-34a) is a microRNAregulated by the p53network at transcriptional level and has been demonstrated to beremarkably down-regulated in a variety of cancers. Exogenous expression of miR-34acould induce cell apoptosis and inhibit cell proliferation and migration targetingNotch pathway and Bcl-2. To increase the delivery efficiency of miR-34a, it isnecessary to construct targeting delivery systems. Chondroitin sulfate (CS) is a naturalpolysaccharide with high affinity to CD44which is over-expressed in many solidtumors, and thus CS could be used as a specific ligand targeting cancer cells viaCD44-mediated endocytosis.Here, chondroitin sulfate was chemically conjugated to poly(amidoamine)(PAMAM) through Michael addition, and then the carrier was employed for realizingthe miR-34a delivery, using CD44-overexpressing tumor cells as model. Thenanoparticles from PAMAMCS and miR-34a were prepared with particle size andzeta-potential of112.5nm and+16.5mV, respectively. In vitro endocytosis analysisindicated that miR-34a could be highly delivered to the CD44+cells, mainly based onclathrin-dependent and CD44-mediated endocytosis. After the miR-34a delivery,obvious apoptosis was detected by flow cytometric analysis, especially high cellapoptosis ratio in p53-/-cells (29.61%in PC-3and21.19%in MIAPaca-2).Meanwhile, the up-regulation of miR-34a could remarkably induce the cell cyclearrest at G1phase. In addition, the miR-34a delivery could suppress the cell migrationusing in vitro transwell migration assay. Western-blot analysis showed that themiR-34a delivery could decrease the expression level of targeting genes, such asBcl-2, which would be favorable for improving the drug sensitivity. The nanocarrier with chondroitin sulfate as ligand could be an effective system for miR-34a deliveryto construct a therapeutic strategy for cancers, especially for solving the multi-drugresistance through the co-delivery of miR-34a and chemotherapeutics.