Sequential dual delivery system based on siCOX-2-loaded gold nanostar and thermal-sensitive liposomes overcome hypoxia-mediated multidrug resistance in tumors

Reversing hypoxia-mediated multidrug resistance (MDR) presents a unique challenge in clinical chemotherapy. Here, a sequential dual delivery system composited with Cyclooxygenase-2 siRNA (siCOX-2) in poly-D-arginine (9R)/2-deoxyglucose (DG)-loaded gold nanostar (GNS) (siCOX-2@RDG) and paclitaxel (PTX)-loaded thermosensitive liposome (PTSL) was proposed to conquer the hypoxia-mediated MDR in tumors. As a result, the prepared siCOX-2@RDG exhibited a starlike morphology with a uniform particle size of 194.36 +/- 1.44 nm and zeta-potential of -11.83 +/- 2.01 mV. In vitro, PTSL displayed expected thermal-responsive release properties. As expected, siCOX-2@RDG displayed exceptional DG-mediated hypoxia-targeting capability both in vitro and in vivo and downregulated the expression of COX-2 successfully. Meanwhile, GNS-triggered hyperthermia elevated the cellular uptake of PTSL in PTX-resistant HepG2(HepG2/PTX) cells in vitro and enhanced the permeability of tumor tissues, thus elevating the valid retention of PTX into solid tumors. Finally, we demonstrated that the sequential dual systems composed of siCOX-2@RDG and PTSL could reverse hypoxia-mediated MDR and exhibit excellent synergistic antitumor effects both in vitro and in vivo, prolonging the survival of tumor-bearing mice. The devised sequential dual systems, composed of two independent nanosystems, have a promising potential to overcome hypoxia-mediated MDR in clinical practice.