Experimental Study Of Brain-Targeted Compound Nano Micelles In The Treatment Of Brain Metastases From HER-2-positive Breast Cancer

Part I Preparation and characterization of brain-targeted paclitaxel-lapatinib loaded drug nano-micellesObjective: The incidence of breast cancer has been high in the past 20 years,especially in many developed countries and regions.The incidence of breast cancer has also been increasing in developing countries and regions.With the extensive application of molecular pattern of breast cancer,and the advent of targeted therapy drugs,the overall prognosis of breast cancer has been significantly improved.The overall survival of HER-2-positive breast cancer is also significantly prolonged with the addition of anti-HER-targeted drugs.However,the incidence of brain metastases increases with the prolongation of survival.Currently the main treatment of brain metastases is still surgery or brain-directed radiation therapy,there is no effective chemotherapy drugs for breast cancer brain metastases.The aim of this study was to develop a novel nano-drug delivery system with brain-targeting function.So that copolymer paclitaxel-lapatinib micelles can be higher concentrations through the blood-brain barrier to the treatment of breast cancer brain metastases.Methods: PEG-PLA was used as carrier to prepare micelles by thin-film hydration method,encapsulated with poorly water-soluble lapatinib and paclitaxel to prepare drug-loaded nano-micelles.The micelles prepared by this method can meet the requirements of further experiments.On this basis,the compound micelles were prepared.The entrapment efficiency and stability of paclitaxel and lapatinib were determined.The target short peptide molecule Angiopep-2,which has the function of pro-brain endothelial cells,was connected with carboxyl group and hydroxyl group.In vitro experiments,it was verified that micelles attached to the target molecule could penetrate the blood-brain barrier.Results: The diameter of micelles was 16.23 ± 0.75 nm and 18.80 ± 0.97 nm,respectively.The drug loading rate of paclitaxel was 2.9 ± 0.8%,the entrapment efficiency was 95.97 ± 3.17%,the drug loading rate of lapatinib was 6.82 ± 1.16%,the entrapment efficiency was 91.21 ± 2.83%,When stored at 4 ° C,the stability of the micelles was good.Compared with micelles without targeting molecules,the micelles attached with the target molecules have more obvious brain targeting function in the same condition.Conclusion: Complex nano-micelles containing paclitaxel and lapatinib have good physical properties.Micelles size is 20 nm,so there is a small amount of micelles through the blood barrier model.After connecting the brain-targeted molecule(Angiopep-2),the composite micelles has a function to penetrate the blood-brain barrier.Part II Experimental Study on Antagonistic Effect and Antagonistic Effect of Compound MicellesObjective: Currently,treatment of breast cancer brain metastases few and ineffective.The first part of the paper has confirmed that in our in vitro experiments,we prepared the compound nano-drug-loaded micelles with good brain targeting function.This part of the study aims to verify the effect of compound targeting nano-drug micelles on the brain metastases of HER-2-positive breast cancer by in vitro cytotoxicity experiments and in vivo animals,which can prolong the survival time of tumor-bearing mice.Methods:In vitro cytotoxicity experiments were performed using two kinds of compound micelles on HER-2 positive and negative cells respectively.The inhibitory ability of the two micelles to the same cells was compared,and the inhibitory ability of the bipolar targeted compound micelles to the two cells was compared.Nude mice were implanted with breast cancer cells--Skbr-3(HER-2 overexpression)by stereotactic stereotaxic apparatus.The behavior status of nude mice was observed several days later.Two nude mice were randomly selected,brain tissue confirmed that breast cancer organize has already in brain.The nude mice were randomly divided into three groups,one group has eight mice.The three groups were normal saline group,untargeted micelles group,and then the target micelles group,respectively(The dose was 7.5 mg / kg / 3 d,lapatinib: paclitaxel = 2: 1).The survival date of each group of tumor-bearing mice was recorded and the survival curve was drawn.Results: These two micelles,the ability to inhibit the two cells,the ability of bipolar targeted compound nano micelles to inhibit cells was stronger.The ability of bipolar targeted compound micelles to inhibit HER-2-positive cell was stronger than inhibit HER-2-negative.In brain metastatic model mice,the micelles with targeted molecules could penetrate the blood-brain barrier and reach the diseased tissues in a shorter time.In the three groups of tumor-bearing mice,the median survival time of the micellar group was 56 days.the median survival time of the untargeted micellar group was 47 days.The survival time of the normal saline group was 35 days.The survival of nude mice was significantly prolonged by injection of ANG-MIC-PTX+LPTN.P=0.0465.Conclusion: Micelles with targeted molecules can penetrate the blood-brain barrier faster and more effectively to reach the brain metastatic lesions to play a therapeutic effect,can effectively extend the survival of brain metastases in mice.