Study On The New Delivery System For The MMP Inhibition And Chemotherapy Improvement

The main reason for the high mortality rate of liver cancer is its high metastasis.Therefore,while seeking methods to kill tumors,inhibiting tumor metastasis is one of the strategies to improve its efficacy.Cancer cells secrete matrix metalloproteinases(MMP2/9),degrade natural barriers such as extra-cellular matrix(ECM),and form channels for tumor metastasis.Inhibiting the activity of MMP2/9 is a common method for reducing metastasis.However,most MMP inhibitors exhibit broad-spectrum actions toward multiple MMP and may cause severe side effects.Therefore,the innovative design of this paper is to design a selective peptide coupled with mercapto doxorubicin to prepare a peptide drug conjugate(PDC),and regulate its self-assembly to form a new delivery system(NDS)with specific inhibition of MMP2 and tumor killing effect,as follows:Here,we designed and synthesized four MMPI peptides(No.1 CKIGLFRWR,No.2 CCKIGLFRWR,No.3 KIGLCCFRWR and No.4 KIGLFRWRCC).CCKIGLFRWR has superior MMP docking strength,can chelate well with Zn2+,and has a strong inhibitory effect on gelatinase.Therefore,we linked it with mercapto doxorubicin(DOX-SH)to produce an amphiphilic peptide-drug conjugate(PDC).In deionized water,PDC will form spherical structure,which particle size of 24.93±0.50 nm and Zeta potential of 24.93±0.50 mV.When solvent changed to PBS,it will assemble into Spherical network structure because the hydrogen bond is strengthened by the action of ions,so that it would be assembled into a spherical network structure.Using SMMC7721 cells as the model,it was found that due to the charge attraction,positively charged PDC tended to accumulate on the surface of tumor cells,which extended the aggregation time on the surface of cell membrane.Cellular pharmacodynamics experiments showed that PDC had tumor cell killing effect and MMP2 selective inhibition effect.In order to neutralize the strong positive charge of PDC for intravenous injection,we successfully synthesized modified polylysine(MPL)shell.NDS with shell and core structure is assembled by electrostatic force.When the molar ratio of PDC to MPL is 1:1.25,in deionized water of pH7.4,the potential decreased from 24.93±0.50 mV to-3.12±0.04mV and the NDS can be self-assembled into a spherical structure with particle size of 140.3 0±45.04 nm.We studied the transport behavior of NDS and found that free DOX and positively charged PDC quickly disappeared from the blood circulation,while the blood circulation time in the NDS group was longer,which could be 3.58 times than that of the DOX group and 4.92 times than that of the PDC group.NDS has strong selective targeting for tumor tissues,and the targeting efficiency is 11.18 times that of the DOX group.The high targeting of tumors reduces the distribution of NDS in the heart and kidney and other tissues,and reduces its toxic side effects to a certain extent.Finally,the antitumor activity and tumor metastasis suppressive effect of NDS in vivo were evaluated using BALB/c male nude mice with highly metastatic HCCLM3-luc cells.The study found that NDS had a good inhibitory effect on tumor growth.Meanwhile,the number of pulmonary metastatic nodules in the NDS group was significantly reduced,and the inhibition rate was up to 93.18%.At the same time,no other significant toxicity-related symptoms were observed in the mice,indicating that NDS has good biocompatibility.In this project,the structure of shell-core delivery system was constructed,which could selectively suppress MMP2 while killing tumors and reduce tumor metastasis.It provides a new idea for the treatment of highly metastatic liver cancer.