Search

Epidermal growth factor receptor (EGFR) is an important anti-cancer therapy target that is applicable to many cancer types. We had previously reported the screening and discovery of a novel peptide ligand against EGFR named GE11. It was shown to bind to EGFR competitively with EGF and mediate gene delivery to cancer cells with high-EGFR expression. In this study, we conjugated GE11 on to liposome surface and examined their binding and distribution to EGFR expressing cancer cells in vitro and in vivo using fluorescence imaging techniques. GE11 liposomes were found to bind specifically and efficiently to EGFR high-expressing cancer cells. In vivo in H1299 xenograft mouse model, GE11 liposomes also extravasated and accumulated into the tumor site preferentially, and demonstrated better targeting and drug delivery capacities.

Objective: To evaluate the efficiency of marker gene and reporter gene transfection into human squamous cell carcinoma of larynx implanted in nude mice with a new EGFR mediated non-viral polypeptide gene delivery system., Methods: Labeled streptavidin biotin (LSAB) was applied to examine over-expression of epidermal growth factor receptor (EGFR) on the squamous cell carcinoma of larynx. The complex of marker gene or reporter gene and gene delivery system was prepared and subsequently inoculated with Hep 2 cells or injected into laryngeal carcinoma implanted on nude mice., Results: Over-expression of EGFR was observed on inoculated Hep 2 cells and on 65% of laryngeal carcinoma specimen examined (15/23). Positive staining was located on the surface of the cells and some of them in the cytoplasma. Green fluorescence was observed on Hep 2 cells under fluorescent microscope 48 hrs after PEGFP-C1 gene transfection and became the strongest 72 hrs after transfection. The rate of transfection was 80% (78/97). Blue staining was noticed 12 hrs after beta-gal gene transfer and it became more remarkable 24 hrs after gene transfection with X-gal staining on the implanted human laryngeal carcinoma on nude mice., Conclusions: Squamous cell carcinoma of head and neck over-expressed EGFR and a non-viral GE7 polypeptide gene delivery system could transfer exogenous genes into laryngeal carcinoma cells and tissues with high efficiency and targeting both in vitro and in vivo suggesting that GE7 would be applicable as a new targeted, high efficient gene delivery system to the gene therapy of squamous cell carcinoma of head and neck.

Objective: To investigate gene transfer efficiency of a novel target non-viral vector GE7 and effects of herpes simplex virus thymidine kinase (HSV(1)-tk)/ganciclovir (GCV) mediated by it in vitro., Methods: The epidermal growth factor receptor (EGF-R) target gene delivery system GE7 was constructed. Human ovarian cancer cell line CAOV3 was transfected in vitro with beta-galactosidase (beta-gal) as reporter gene and HSV(1)-tk gene as therapeutic gene using this gene delivery system. By means of the assay of X-gal staining, Northern blotting, cell growth-inhibiting curve and so on, the transferring efficiency of exogenous genes and killing effects are observed., Results: It showed that gene transfer efficiency is over 80%. When 10 mg/L GCV was put into ovarian cells transfected with HSV(1)-tk gene, 95% of cells were killed, and the apoptosis ratio reached up to 30., Conclusions: The GE7 gene delivery system is an effective and safe delivery system. GE7/HSV(1)-tk/GCV therapeutic gene system is appraising for ovarian cancer.

Purpose: To construct an EGF receptor (EGF-R)-mediated histone H1(0)-based gene delivery system for gene therapy., Methods: A recombinant DNA containing histone H1(0), EGF-R ligand, and endosomalytic domains was constructed in a prokaryotic vector and expressed in E. coli. Expression of the beta-galactosidase (beta-gal) gene in the tumor cells and tissues was observed after transduction of the beta-gal gene packaged by purified fusion proteins in vitro and in vivo., Results: As an extension of the research on previously reported chemically synthetic composite polypeptide gene delivery systems, this genetically engineered polypeptide has proved to be capable of targeting the beta-galactosidase (beta-gal) gene into EGF-R-positive cancer cells both in vitro and in vivo. We also studied the time course of beta-gal gene expression in tumor tissues delivered in vivo by this polypeptide vector. At 24 h after administration, expression of the beta-galactosidase gene in tumor reached peak levels. The dosage optimization of administered polyplex was also investigated. The optimal dose of polyplex per mouse was 1 microg DNA packaged by 3 microg of composite polypeptide., Conclusions: The genetically engineered polypeptide based on histone H1(0) is a promising gene delivery system targeting EGF-R.

Based on the fact that aberrant overexpression of some growth factor receptors was observed in a variety of human cancer cells, a novel nonviral gene delivery system GE7, which contains a 16-amino-acid ligand for identifying EGF receptor was constructed for tumor-targeted gene therapy. Intravenous administration of GE7 system revealed that it has the ability to target beta-galactosidase (beta-gal) reporter gene into murine hepatoma (Hepa) cells. Owing to the limited antitumor effects elicited by a single-gene transfer, recent efforts to treat malignancy using combined gene therapy have been accomplished with varying degrees of success. In this study, the human cyclin-dependent kinase inhibitor gene p21(WAF-1) and the murine cytokine gene granulocyte-macrophage colony-stimulating factor (GM-CSF) were used simultaneously for in vivo gene therapy through systemic injection of the EGF R targeted GE7/DNA complex into murine hepatoma-bearing mice. The results demonstrated that combined administration of p21(WAF-1) and GM-CSF could remarkably inhibit the growth of subcutaneously transplanted hepatoma Hepa cells, and significantly increase the survival rate of tumor-bearing mice. The activities of natural killer (NK) cells and specific cytotoxic T lymphocytes (CTL) were clearly enhanced after combined gene therapy. In vitro experiments showed that p21(WAF-1) gene transfer exhibited a suppressive function on the growth of Hepa cells and the expression of H-2K(b) and B7-1 molecules on Hepa cells increased significantly after combined genes delivery. All these results suggested that the GE7 system was able to target therapeutic genes efficiently to cancer cells, which showed high EGF R expression. The cotransfer of p21(WAF-1) and GM-CSF genes apparently inhibited the growth of tumors through (a) the arrest of tumor cell growth and (b) the enhancement of systemic antitumor immunity.