Viral Vectors Selective for Metastatic Breast Cancer Tumor Cells
Final rept. 1 Oct 1998-1 Oct 2002
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The relative ease with which polyomavirus VPI quasi-equivalent assemblies VLPs can be expressed and purified has prompted us to develop them as vectors for gene therapy. We have introduced sequences into the surface-exposed loops of VPI that will target VbPs to receptors frequently expressed on breast cancer cells. We have introduced into VPI loops BC, DE, EF and HI, sequences capable of binding to the urokinase plasminogen activator uPA receptor or the ErbB2 receptor. Introduction of these sequences renders most of the modified VPI proteins insoluble when expressed at high levels in insect cells, although some modified proteins such as VPlEF-uPA10-34, -uPA1-60 and -ErbB26.1 are partly soluble. Conditions have been developed to improve yield and solubility. The efficiency of self-assembly of these modified VPl proteins appears to be reduced as compared to VPlwt protein, however co-expression with VPlHI-FLAG improves yields. That the VLPs contain the co-expressed VPl proteins has been established by demonstrating VPlEF-uPA1-60 proteins migrating at the position of native VLPs in sucrose velocity sedimentation and co-precipitation with VPlEF-FLAG proteins captured by anti-FLAG antibody. Specificity for receptors present on cancer cell surfaces has been defined.
- Genetic Engineering and Molecular Biology
- Medicine and Medical Research