Preparation Of Loaded Paclitaxel And JQ1 PLGA Nanoparticles And Their Anti-tumor Effects

ObjectiveIn the course of immunotherapy for tumors,programmed cell death-ligand 1(PD-L1)on the surface of tumor cells depletes the function of cytotoxic T cells,reduces their killing effect on tumors,and then generates immune escape.As an effective inhibitor of bromo structural region protein BRD4,JQ1 can inhibit the expression of PD-L1 on the surface of tumors and overcome the immune escape of tumor.Paclitaxel(PTX),as a classical antitumor drug,is widely used in the treatment of cancer.However,paclitaxel is prone to multidrug resistance,and paclitaxel and JQ1 are poorly soluble drugs,which limit its clinical application.Therefore,in this study,paclitaxel and JQ1 were encapsulated in PLGA nanoparticles as model drugs and nanoparticles as delivery vectors through co-delivery strategy,in order to exert anti-tumor effect by combining the direct killing effect of paclitaxel on cancer cells and the inhibition effect of JQ1 on immune escape.To solve the problem of poor solubility of the two drugs and improve their bioavailability to achieve good anti-tumor therapeutic effect.MethodsThe determination method of paclitaxel and JQ1 was established by high performance liquid chromatography.Biodegradable PLGA was used as polymer carrier material and paclitaxel and JQ1 as model drug.JQ1-PTX-PLGA nanoparticles were prepared by ultrasonic emulsification solvent evaporation method using biodegradable PLGA as polymer carrier materials and paclitaxel and JQ1 as model drugs.The physicochemical properties of the prepared PLGA nanoparticles were characterized by particle size and polydispersity index,transmission electron microscopy,encapsulation efficiency analysis and infrared spectroscopy.Using melanoma B16 cells as a model,the inhibitory effect of the prepared nanoparticles on the expression of PD-L1 on the surface of tumor cells was investigated by in vitro cell experiments.Rats were used as model animals to investigate the pharmacokinetics of rats after tail vein injection of nanoparticles,and the relevant pharmacokinetic parameters were calculated by DAS software.By subcutaneous injection of B16 melanocyte,the animal model of tumor-bearing mice was constructed.After tail vein injection of nanoparticles,the weight and tumor volume of mice were recorded,and the therapeutic effect of the prepared nanoparticles on tumors was evaluated.Flow cytometry was used to detect Treg cells,T cells and γ-interferon in order to explore the mechanism of nanoparticles inhibiting tumors.The damage of PTX-JQ1-PLGA nanoparticles in the treatment of tumors was evaluated by detecting biochemical indicators such as alanine aminotransferase(ALT/GPT),aspartate aminotransferase(AST/GOT)and total bilirubin in the tumor model of the tumor model and pathological sections of organs.Infrared spectrum analysis showed that PTX and JQ1 had good compatibility with the carrier materials used to prepare PLGA nanoparticles.Drugs were encapsulated or embedded on the framework of PLGA to form spherical nanoparticles.ResultsThe particle sizes of PTX-PLGA nanoparticles,JQ1-PLGA nanoparticles and PTX-JQ1-PLGA nanoparticles were 210.1nm,250.6nm and 284.8nm,respectively.The morphology of the prepared nanoparticles was observed under electron microscopy as regular spherical structure.The encapsulation efficiency of paclitaxel and JQ1 in PTX-JQ1-PLGA nanoparticles was 70.8 % and 57.3 %,respectively.According to the results of flow analysis,JQ1 can inhibit the expression of PD-L1 on the surface of B16 melanoma cells in an in vitro cell model.There was no statistically significant difference in the inhibition of PD-L1 expression between the prepared JQ1-PLGA nanoparticles and the same concentration of JQ1suspensions;however,the high concentration of JQ1 inhibited PD-L1 better than the lower concentration of JQ1.There is a dependency between dose effects.The results show that the preparation of JQ1 nanoparticles does not affect the activity of JQ1,which confirms that PLGA nanoparticles can be used to deliver JQ1,and provides a feasibility for the joint application of JQ1 paclitaxel.The anti-tumor results of melanoma model mice showed that JQ1-PLGA nanoparticles and PTX-JQ1-PLGA nanoparticles had good anti-tumor effects,with the inhibition rates of 48 % and 55 %.The results of infrared spectroscopy indicated that PTX and JQ1 had good compatibility with the carrier materials used to prepare PLGA nanoparticles.The drug was entrapped or embedded on the backbone of the carrier material PLGA to form spherical nanoparticles.Flow cytometry showed that the proportion of Treg cells in spleen and drainage lymph nodes of mice decreased,the activity of tumor was inhibited,the proportion of active T cells increased and the proportion of γ-interferon increased,which enhanced the anti-tumor effect.The results of TUNEL staining with HE stains in tumor tissue showed that PTX-JQ1-PLGA nanoparticles had good anti-tumor effect and could induce apoptosis of tumor cells.Pathological sections and biochemical tests showed that the prepared PTX-PLGA nanoparticles had slight hepatotoxicity.ConclusionIn this study,PLGA nanoparticles loaded with PTX and JQ1 were prepared.From the perspective of direct killing effect of paclitaxel on cancer cells and blocking effect of JQ1 on surface inhibitors of cancer cells,the anti-tumor effect of co-delivery of paclitaxel and JQ1 was discussed in order to provide a new strategy for the treatment of cancer.