| Lung cancer is one of the mortalist cancers in human beings,and its mortality rate in 2011 statistics shows that it exceeds the sum of the four most common cancers(colon cancer,breast cancer,pancreatic cancer and prostatic cancer).The types of lung cancer can be divided into small cell lung cancer and non-small cell lung cancer,most of which are non-small cell lung cancer.Chemotherapy combined with surgical resection is widely used for advanced non-small cell lung cancer.Because of the drug resistance and heterogeneity of tissue marker expression,immunotherapy and targeted therapy were also used in the treatment of non-small cell lung cancer.T7 is a polypeptide that has been proved to be able to target the over-expressed transferrin receptor in a variety of tumor cells.It has been used to target glioma cancer,hepatocellular carcinoma,breast cancer,leukemia and other diseases.IM peptide is a heptapeptide selected by phage display technology through four rounds of biopsies,which has a specific targeting effect on A549 cells.Its mechanism is that A549 cells have a high level of fibrinogen mRNA expression,and fibrin promotes epithelial stromal transformation,while IM peptide can specifically bind to the capsule of fibrin produced in the process of fibrinogen to fibrin transformation.To improve the distribution and therapeutic effects of chemotheraputical drugs for lung cancer,we firstly synthetized new targeted ligand-lipids materials,DSPE-PEG2000-T7 and DSPE-PEG-IM,then constructed the liposomes(T7/IM-LPs)modified by IM peptide and T7 peptide,and evaluated the physical and chemical properties of T7/IM-LPs and drug loaded liposomes,such as particle size,ζ potential,morphology,encapsulation efficiency and in vitro release.The targeting efficiency of the targeted liposomal targeting system on lung cancer was verified by cellular uptake experiment,pharmacokinetic and pharmacodynamic analysis in vivo and in vivo imaging.The results of flow cytometry and confocal fluorescence microscopy showed that the cellular uptake of double-ligand liposomes was better than that of single-ligand liposomes and common liposomes.T7/IM-LP-IR780 reached the tumor site in nude mice bearing A549 cell lung tumor at 6 h,and reached the maximum value at 12 h,while it was rarely distributed in other parts,indicating that T7 peptide and IM peptide can effectively target lung cancer cells,laying a foundation for later animal treatment experiments and in vivo evaluation.Hydroxycamptothecin liposomes were prepared by using hydroxycamptothecin(HCPT)as anticancer drug.The particle size of the liposomes was about 120 nm,and the encapsulation efficiency was in the range of 58%～60%.The results of MTT assay showed that the cytotoxicity of T7/IM-LP-HCPT was much higher than the single-targeted and non-targeted LP-HCPT.Then,the pharmacokinetics,tissue distribution and pharmacodynamics of LP-HCPT,T7-LP-HCPT,IM-LP-HCPT and T7/IM-LP-HCPT in tumor bearing mice were studied.Firstly,the chromatographic conditions for the determination of hydroxycamptothecin were studied.The mobile phase consisted of 0.1%triethylamine acetic acid buffer(pH=6.5)and acetonitrile(V/V=75:25).The wavelength of the detection were Ex=382 nm and Em=528 nm,respectively.The flow rate was controlled at 1.0 mL/min.It can be seen from the linear equation that HCPT in plasma and tissue samples has a good linear relationship in the concentration range of 2～100 μg/mL.In the in vivo anti-tumor test,T7/IM-LP-HCPT can significantly inhibit the growth of tumor,without obvious systemic toxicity.In this study,we successfully synthetized new targeted ligand-lipids materials,DSPE-PEG2000-T7 and DSPE-PEG-IM,then constructed a liposomal drug delivery system with IM peptide and T7 peptide as double targets.The encapsulation of HCPT in liposomes can effectively improve the distribution of HCPT in lung cancer tumor and change the distribution behavior in vivo.It will lay a foundation for the study of the specific mechanism of polypeptides targeting lung cancer cells. |
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