Studies On SP90 And CPP Mediated Breast Cancer Cell Targeting Protein Delivery Systems

Lack of satisfactory specificity towards tumor cells and poor delivery efficiency are the major drawbacks with conventional anti-cancer drugs.Tumour targeting peptide and cell-penetrating peptide can enhancethe specificity of tissues or cellsand intracellulardrug delivery efficiencyrespectively,combinationof them is more conducive to develophigh efficiency,low toxicity and specificity anti-tumor drugs.Genetic engineering drugs have arisen in prevention and treatment of various diseases,exploring targeted anti-cancer gene engineering drug is of great significance to conquer cancer.In this paper,a chimeric peptide SP90-C,tumor-targeting peptide SP90 in conjunction with a cell-penetrating peptide C-peptide,for efficient and targeted breast tumor drug delivery was designed and characterized.Firstly,EGFP,SP90-EGFP,SP90-EGFP-C,SP90-VPR and SP90-VPR-Crecombinantswere successfully expression in Escherichia coli and purified by nickel afinity chromatography.Then,using green fluorescent protein as the report protein,the abilityof SP90 promoting the proteinstargeting breast cancer cellswas verified by fluorescence microscope and flow cytometry analysis.Compared to SP90 alone,chimeric peptide,SP90-C,increased the intracellular delivery efficiency by 10-12 foldat the concentration of 1.5 ?M.Pull-Down and Far-Western blotting assay revealed an approximate 35 kDa protein that expressed differently in high metastatic breast cancer cell-line MDA-MB-231,low metastatic breast cancer cell-line MCF-7 and normal breast cell NAFB.Finally,the specifically breast cancercell-killing ability was compared between SP90-VPR and SP90-VPR-C in normal breast cell NAFB and breast cancer cells MDA-MB-231 and MCF-7.Two VPR fusion proteins inhibited the growth of MDA-MB-231 and MCF-7,but not NAFB.Flow cytometry analysis showed that bothSP90-VPR and SP90-VPR-C proteins can stimulate breast cancer cells apoptosis.The efficiencyof induced apoptosisof SP90-VPR-C protein for breast cancer cells is higher than SP90-VPR protein,and the main mechanismwasarrest cells in G2/M phase and S phase,SP90-VPR protein was mainly G2/M phase retardation and SP90-VPR-C protein was mainly S phase retardation.The results showed that SP90 can be used for efficient breast cancer cell drug-targeting and C-Peptide has synergistic effect on SP90.