Studies On The Synthesis Of Functional Peptides Modified Doxorubicins And Their Antitumor Activities In Vivo And In Vitro

Doxorubicin is a chemotherapeutic drug that has been used in various cancers treatment,such as breast,stomach and liver cancers.In spite of this,there are still some difficiencies of doxorubicin that compromise the therapeutic effects for clinic application.For example,doxorubicin usually shows low loading rate and inflicts severe side effects on patients.Therefore,it is of big importance to develop new methods to mofify doxorubicin to achieve higher loading rate and reducing the side effects brought by doxorubicin,which could provide better prognosis for cancer patients.The purpose of this work is to improve the biocompatibility,drug load rate and reduce side effects of doxorubicin by preparing six polypeptides-doxorubicins.The HepG2 cells were used for testing the tumor cell toxicity.In vivo metabolization,biodistribution and hematology index were investigated using the synthesized polypeptides-doxorubicins.These works will benifit their clinical trials and further applications.Methods and results:1.Three kinds of peptides(NGR,RGD,YIGSR)and perforating peptides(CGNKRTR,RKKRRRR,RRRRRRR)were prepared by solid phase synthesis.After separation and purification,the conjugation of polypeptide-doxorubicin was performed by three-step liquid phase.Six drugs were synthesized containing doxorubicin and functional polypeptides.After the characterization,the products were identified with the purity above 95 %.2.The cellular uptake was observed by confocal microscopy.The toxicities of doxorubicin and analogues were studied by MTT assay.The results showed that the synthesized functional peptide-doxorubicin can largely accumulate in tumor cells,inhibiting the growth of tumor cells.Moreover,doxorubicin conjugated with cell transmembrane peptide showed PH-responsive property for tumor acidic intracelluar environment,which exhibited abundant tumor cell distribution both in nucleus and cytoplasm.3.The distribution of the synthesized drugs in tumor model animals was detected by using the living imaging system.Functional peptide-doxorubicin showed high tumor uptake after administration.Besides,compared with doxorubicin,the functional peptide-doxorubicin exhibited decreased distribution in non-targeted organs.Furthermore,in vivo toxicity was evlaluated by analyzing hematology parameters on a blood cell counter.The results showed that the effects of doxorubicin on white blood cells,lymphocytes,and platelets were significant.However,no significant changes were found on functional peptide-doxorubicin treated mice.The effects of all drugs on erythrocytes were neligible,but the effects on granulocytes significant difference compared with control group.As the elimination of drug metabolism,each indicator gradually returned to normal level.Research conclusions:The above research indicates that the modification used in this research to conjugate doxorubicin with functional polypeptides is a feasible way to develop clinic promising drugs.The functional peptide-doxorubicin were able to accumulate in the HepG2 cells and reduce the non-target organs distribution.The drugs including YIGSR-DOX and NGR-DOX showed better tumor target properties,so as to lower the toxicity to main organs.The effects of all six functional peptide-doxorubicins on blood cells decreased with metabolic elimination.Therefore,this paper provides important theoretical support for the development of peptide-doxorubicin in future clinic investigation.