title: Photochemically enhanced gene transfection increases the cytotoxicity of the herpes simplex virus thymidine kinase gene combined with ganciclovir.
abstract: Tumor targeting is an important issue in cancer gene therapy. We have developed a gene transfection method, based on light-inducible photochemical internalization (PCI) of a transgene, to improve gene delivery and expression selectively in illuminated areas, for example, in tumors. In the present work, we demonstrate that PCI improved the nonviral vector polyethylenimine (PEI)-mediated transfection of a therapeutic gene, the 'suicide' gene encoding herpes simplex virus thymidine kinase (HSVtk). In U87MG glioblastoma cells in vitro, the photochemical treatment stimulated expression of the HSVtk transgene, and, consequently, enhanced cell killing by the subsequent treatment with the prodrug ganciclovir (GCV). When relatively low doses of DNA (1 microg/ml) and the PEI vector (N/P 4) were used, HSVtk gene transfection followed by the GCV treatment did not have an effect on cell survival unless the photochemical treatment was performed, which potentiated the cytotoxicity to 90%. These findings indicate that photochemical transfection allows: (i) selective enhancement in gene expression and gene-mediated biological effects (cell killing by the Hsvtk/GCV approach) in response to illumination; (ii) the use of low, suboptimal for the nonviral transfection methods without PCI, doses of both DNA and the vector, which may be relevant and advantageous for therapeutic gene transfer in vivo.
authors.affiliation: Department of Biophysics, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway. lina.prasmickaite@labmed.uio.no
authors.forename: Lina
authors.initials: L
authors.lastname: Prasmickaite
authors.forename: Anders
authors.initials: A
authors.lastname: Høgset
authors.forename: Vibeke Murberg
authors.initials: VM
authors.lastname: Olsen
authors.forename: Olav
authors.initials: O
authors.lastname: Kaalhus
authors.forename: Svein-Ole
authors.initials: SO
authors.lastname: Mikalsen
authors.forename: Kristian
authors.initials: K
authors.lastname: Berg
mesh_terms: D002450:Cell Communication / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015774:Ganciclovir / Q000494:pharmacology*; D017629:Gap Junctions / Q000187:drug effects; D005822:Genetic Vectors; D006801:Humans; D008027:Light; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000494:pharmacology; D011094:Polyethyleneimine / Q000737:chemistry; D018139:Simplexvirus / Q000201:enzymology* / Q000235:genetics; D013937:Thymidine Kinase / Q000009:adverse effects* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014162:Transfection / Q000379:methods*
chemical_list: D017319:Photosensitizing Agents; D011094:Polyethyleneimine; D013937:Thymidine Kinase; D015774:Ganciclovir