Regulation and Utilization of Host Response of Polymer Vascular Disrupting Agent

Author:Jiang Jian

Supervisor:li zuo


Degree Year:2019





Cancer is one of the public problems and the second leading cause of human death in the world,having received more and more attention.However,the widely used small molecule chemotherapeutic drugs in clinic still have many problems,such as poor water solubility,poor targeting,large toxicity and serious side effects.Nano-drugs have many advantages in improving drug solubility,increasing targeted drug delivery and reducing systemic toxicity and side effects in cancer treatment.As a new strategy for solid tumors therapy,vascular disrupting therapy has shown good therapeutic effect and broad application prospects.Vascular disrupting agents could disrupt neovascularization of tumors,destroy vascular endothelial cells,cause hemorrhage and blockage of tumor blood vessels,resulting in blocking the supply of oxygen and nutrients of tumors and killing tumors.The vascular disrupting agents nanodrug could enrich at tumor blood vessel and kill tumor better than small molecular vascular disrupting agents.In this dissertation,we leverage poly-amino acid materials as carriers to prepare vascular disrupting agents nanodrug.Through further investegating the host responses caused by vascular disrupting agents nanodrug,we design cooperartive therapy strategies based on the special physiological and pathological tumor environment to realize the better tumor therapy effect.The main research contents and conclusions of this dissertation are summarized as follows:1)Vascular disrupting agent nanodrug(CA4-NPs)was prepared by Yamaguchi reaction.Vascular disrupting agent nanodrug PLG-g-mPEG/CA4(CA4-NPs)was prepared by esterification of glutamic acid carboxyl group from poly(L-glutamic acid)-graft-methoxy poly(ethylene glycol)(PLG-g-mPEG)with hydroxyl group from combretastatin A4(CA4).It was confirmed by 1H NMR spectrum that CA4 was successfully grafted onto the PLG-g-mPEG,and the drug loading content of CA4 in CA4-NPs was determined by high performance liquid chromatography(HPLC).In vivo and in vitro experiments showed that CA4-NPs had good stability,high drug loading efficacy and good application prospects.However,CA4-NPs could aggravate the hypoxia level of tumor tissues after CA4-NPs treatment because of destroyed tumor blood vessels,which would lead to a series of host responses.2)Focus on the problem that the expression of CXCR4 in tumor tissues is increased after CA4-NPs treatment,which might promote the metastasis of tumor cells to normal organs.So,we designed a cooperative strategy that combines CXCR4 antagonist plerixafor(PLF)with CA4-NPs treatment,which could inhibit tumor growth and metastasis simultaneously.Plerixafor(also termed AMD3100),a CXCR4 antagonist,was approved by FDA for Multiple Myeloma and Non-Hodgkin’s Lymphoma in mobilizing hematopoietic stem cells for autologous stem-cell transplantation through subcutaneous injection.Combination of intraperitoneal injection of PLF and intravenous injection of CA4-NPs can inhibit tumor growth and lung metastasis effectively on triple negative breast cancer 4T1 orthotopic mouse model.This cooperative strategy is simple and convenient,which gives a strong theoretical evidence for the clinical combination of vascular disrupting agents and CXCR4 antagonists.3)Focus on the expression of MMP9 increased in tumor tissues after CA4-NPs treatment,MMP9-activated doxorubicin prodrug was designed and synthesized.MMP9-activated doxorubicin small molecule(MMP9-DOX)was prepared by binding doxorubicin(DOX)to MMP9-activated polypeptide(Fmoc-GPLGL).Then MMP9-activated doxorubicin nanodrug(MMP9-DOX-NPs)was prepared by loading MMP9-DOX with poly(ethylene glycol)-b-poly(L-glutamic acid-co-L-phenylalanine).In vivo and in vitro experiments showed that MMP9-DOX-NPs were sensitive to MMP9 and had good stability and cytotoxicity.Which has potential application prospects.4)The difference of tumor associated enzymes expression in tumor tissues and normal organs is not obvious enough,which limits the therapeutic effect of tumor-associated-enzyme-activated prodrug(TAEAP).Based on this problem,a cooperative therapy strategy of combining CA4-NPs and MMP9-DOX-NPs was designed.CA4-NPs induced the expression of MMP9 increase in tumor tissues selectively,which boosted MMP9-DOX-NPs targeting release in tumor tissues.In vivo experiments showed that,the combination group of CA4-NPs and MMP9-DOX-NPs could promote the targeting release of MMP9-DOX-NPs in tumor tissues.The amount of DOX released from CA4-NPs+MMP9-DOX-NPs group was 3.7-fold compared with that released by MMP9-DOX-NPs group.At the same time,the inhibition rate of CA4-NPs+MMP9-DOX-NPs group was significantly increased in the mice triple negative breast cancer 4T1 orthotopic mouse model and colon cancer C26 subcutaneous mouse model.This cooperative system can selectively induce the expression of MMP9 increase in tumor tissues by vascular disrupting agent nanodrug,boost the selective release of MMP9-activated doxorubicin nanodrug in tumor tissues,and improve the therapeutic effect of tumor inhibition.It is significant for the promotion of tumor-associated-enzyme-activated prodrug(TAEAP).Through the investigation of this dissertation,the appropriate cooperative therapy strategies were designed according to the host responses after CA4-NPs treatment.The results were expected to provide the fundamental evidence for clinical application of vascular disrupting agent nanodrug.