Photochemical Internalization of Transgenes Controlled by the Heat-shock Protein 70 Promoter

• Published in: Photochemistry and photobiology 2006-05, Vol.82 (3), p.809-816
• Main Authors: Prasmickaite, Lina, Hellum, Marit, Kaalhus, Olav, Høgset, Anders, Wagner, Ernst, Berg, Kristian
• Format: Article
• Language: English
• Subjects: Cell Line, Tumor; Cytomegalovirus; Endocytosis; Gene therapy; Genes; Genetic Therapy - methods; HSP70 Heat-Shock Proteins - genetics; Humans; Photochemistry; Plasmids - administration & dosage; Plasmids - pharmacokinetics; Porphyrins - pharmacology; Promoter Regions, Genetic; Proteins; Transfection - methods; Transgenes; Up-Regulation - drug effects; Up-Regulation - genetics
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1562/2005-11-07-RA-731

Photochemical internalization (PCI) is a targeting technique that facilitates endosomal escape of macromolecules, such as transgenes, in response to photochemical treatment with endosome/lysosome-localized photosensitizers, such as disulfonated meso-tetraphenylporphine (TPPS2a). In gene therapy this leads to enhanced transgene expression. Moreover, photochemical treatment generally activates transcription of stress-response genes, such as heat-shock proteins (HSPs), via stimulation of corresponding promoters. Therefore, we used HSP70 (HSPp; a promoter from the HSP family gene) and investigated whether the PCI stimulus could also activate HSPp and thereby stimulate transcription (expression) of the HSPp-controlled transgene internalized via PCI. Using human colorectal carcinoma and hepatoma cell lines in vitro, we showed that TPPS2a-based photochemical treatment enhances expression of cellular HSP70, which correlated with a photochemically enhanced expression (approximately 2-fold, at PCI-optimal doses) of the HSPp-controlled transgene integrated in the genome. Furthermore, PCI enhanced expression of the HSPp-controlled episomal transgene delivered as a plasmid. However, in plasmid-based transfection, PCI-mediated enhancement with HSPp did not exceed the enhancement achieved with the constitutive active CMV promoter. In conclusion, we demonstrated that the PCI-relevant treatment initiates HSP70 response and that the HSP70 promoter can be used in combination with PCI, leading to PCI-enhanced expression of the HSPp-controlled transgene.