Mitochondrial And Nrf2 Dual-Targeting Tetravalent Platinum Nanoprodrug On Oral Cancer Therapy

Background:Platinum is one of the most widely used classical drugs in cancer chemotherapy.Platinum-based protocols accounts for more than 90%in head and neck cancer chemotherapy.In addition to the classical mechanism of damaging DNA,platinum has been proven to produce high level of reactive oxygen species(ROS)in cells,which results in oxidative damage and killing effect to the cells.However,as the platinum drugs used in clinic at present lack properties of accurate delivery and precise drug release,and tumor cells often develop strong antioxidant systems against the ROS produced by platinum drugs,platinum drugs are facing the bottleneck of tumor drug-resistance and systemic side-effects,which seriously limits their overall clinical performance,and is a key and difficult problem in anti-tumor drugs design.Scheme:Based on the current bottleneck of platinum drugs,we designed a kind of mitochondrial and Nrf2 dual-targeting tetravalent platinum nanoprodrug.On the one hand,due to the EPR effect of tumor,nanocarrier can specifically enrich the drug in the tumor site,and then in response to the high concentration of GSH in tumor cells,tetravalent platinum will be reduced to bivalent platinum precisely.Combined with its mitochondrial targeting property,it will finally lead to concentrated production of high concentration of ROS in tumor cells mitochondria.On the other hand,the reduction of tetravalent platinum results in the consumption of antioxidants,and miR-144-3p inhibits the antioxidant defense response mediated by Nrf2.Increase in ROS production and decrease in ROS elimination work together to break the redox balance of tumor cells.As a result,anti-tumor therapy with high efficiency and low side-effect can be achieved.Methods and results:This study is mainly carried out from three aspects:the preparation and characterization of the tetravalent platinum nanoprodrug,the evaluation of the targeting performance and anti-tumor efficacy in vitro,and the evaluation of the anti-tumor efficacy and safety in vivo.Firstly,mitochondrial targeting tetravalent platinum nanoprodrug P(Pt-RhB)NPs were successfully prepared through self-assembly method.Then miR-144-3p was loaded through electrostatic interaction to obtain P(Pt-RhB)NPs@miR-144-3p,which was confirmed by agarose gel electrophoresis retardation experiment.Afterwards,the size,potential,and morphology were characterized by DLS and TEM,which proved that it could form spherical nanoparticles with suitable size and potential.Moreover,the tetravalent platinum nanoprodrug P(Pt-RhB)NPs was proven to release free platinum in a slow way in respond to GSH.In vitro,it was proven that P(Pt-RhB)NPs@miRNA can successfully enter tumor cells and target mitochondria through flow cytometry and laser confocal microscopy,and P(Pt-RhB)NPs@miR-144-3p can effectively improve the anti-tumor effect of platinum drugs through CCK-8 experiment.In vivo,fluorescence imaging showed that P(Pt-RhB)NPs@miR-144-3p could passively target the tumor site.Excellent anti-tumor effect was proven by tumor volume and weight results,tumor tissue H&E staining and TUNEL staining.Additionally,it was proven to have excellent biosafety by hemolysis test,change in body weight and survival rate of mice,biochemical analysis of serum and H&E staining of important organ tissues.Conclusions:Mitochondrial and Nrf2 dual-targeting tetravalent platinum nanoprodrug can accurately deliver platinum drug to the mitochondria of tumor cells,and cooperate with the down-regulation of antioxidant level induced by Nrf2 inhibition,thereby making more efficient and safer anti-tumor therapy into reality.