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 lightinducible 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 mg/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.

Photochemical Internalization: A New Tool for Drug Delivery

“…Polylysine (with reporter gene EGFP) TPPS2a, TPPS4, AlPcS2a [28][29][30]85] Polyethyleneimine (PEI) (with reporter genes eGFP, luciferase and therapeutic gene HSV-thymidine kinase) TPPS2a,AlPcS2a [29,33,79] Glucosylated PEI with p53 gene TPPS2a [34,87] Glucosylated PEI with PTEN gene TPPS2a [35] NLS-peptide/plasmid complex complexed to a dendrimer-photosensitizer conjugate Dendrimer phthalocyanine [45] Cationic lipids (with reporter eGFP)* AlPcS2a [88] Targeted Gene Delivery:…”

Visible light regulates neurite outgrowth of nerve cells

“…Visible light has been used not only as a potential activator of photoactive therapeutic agents (Samia et al 2003;Bakalova et al 2004) but also as a therapeutic agent itself (Hogset et al 2002;Prasmickaite et al 2004;Chen et al 2005), although it remains unclear how visible light interacts with tissue and cells. Several researchers have found that violet-blue light (380-500 nm) disrupts DNA integrity and cellular processes such as mitochondrial function and mitosis, which are probably mediated by light-induced reactive oxygen species (ROS) (Aggarwal et al 1978;Gorgidze et al 1998;Pflaum et al 1998;Lewis et al 2005).…”

Cytosolic Delivery of Liposomally Targeted Proteins Induced by Photochemical Internalization

“…Selbo et al demonstrated that the use of PCI enhanced the potency of the plant toxin gelonin in inhibiting cellular protein synthesis by a factor of 300 (21). In addition, the low-molecular weight drug bleomycin (22), antigenic peptides (23), immunotoxins (24,25), peptide nucleic acids (26) and even colloidal carriers for gene delivery (27)(28)(29) have been successfully delivered into the cytosol via PCI. These agents generally are not able to reach their intracellular target site efficiently, due to lack of capability to pass cellular membranes and/or the occurrence of degradation within endocytic vesicles.…”