Abstract 3318: Cytotoxic effect of photosensitive fluorescent protein KillerRed-expressing adenovirus against human cancer cells.

Abstract

Abstract Photodynamic therapy (PDT) is an anticancer therapy to induce tumor-specific cytotoxicity by accumulation of photosensitizers (PSs) and following non-toxic light irradiation to tumor tissues. Non-toxic light irradiation induces the PS-mediated generation of reactive oxygen species (ROS) and subsequent cytotoxicity in tumor cells. For clinical application, some kinds of PSs, such as photofrin and laserphyrin, are intravenously injected before light irradiation in anticancer PDT. However, the lack of sufficient and continuous accumulation of PSs in tumor tissues makes difficult to eradicate tumor cells by PDT. Therefore, the development of novel PSs that accumulate to tumor tissues more efficiently and persistently is required to improve the antitumor effect of PDT. A bioengineered fluorescent protein KillerRed has been previously reported to generate ROS upon green light irradiation, suggesting a potential of KillerRed fluorescent protein as a novel PS. We recently confirmed that transient or stable transfection with KillerRed-expressing plasmid vector efficiently suppressed the cell viability through induction of ROS-mediated apoptosis in various types of human cancer cells when combined with light irradiation. In this study, we constructed non-replicative adenovirus expressing cytotoxic KillerRed (Ad-KillerRed) or non-cytotoxic red fluorescent protein Katushka (Ad-Katushka). The cytotoxic effect of these viruses was investigated in human cancer H1299, HCT116 and HT29 cells in combination with light irradiation. Infection with Ad-KillerRed or Ad-Katushka did not induce any cytotoxic effect in human cancer cells without light irradiation. When combined with light irradiation, human cancer cells infected with Ad-KillerRed, but not Ad-Katushka, showed morphological change like round-shape. However, the cell viability was not significantly suppressed in Ad-KillerRed-infected cancer cells after light irradiation. These results suggest that replication-competent adenovirus is necessary to efficiently induce KillerRed-mediated cytotoxic effect in human cancer cells in combination with light irradiation. Now we are planning to generate the replication-competent oncolytic adenovirus expressing KillerRed and investigate its antitumor effect on the in vitro and in vivo settings. Citation Format: Kiyoto Takehara, Hiroshi Tazawa, Yuuri Hashimoto, Hiroyuki Kishimoto, Nobuhiro Narii, Hiroyuki Mizuguchi, Toshiyoshi Fujiwara. Cytotoxic effect of photosensitive fluorescent protein KillerRed-expressing adenovirus against human cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3318. doi:10.1158/1538-7445.AM2013-3318