We report here a tumor-targeting masked phototherapeutic agent 1 (PT-1). This system contains SN-38 - a prodrug of the topoisomerase I inhibitor irinotecan. Topoisomerase I is a vital enzyme that controls DNA topology during replication, transcription, and recombination. An elevated level of topoisomerase I is found in many carcinomas, making it an attractive target for the development of effective anticancer drugs. In addition, PT-1 contains both a photo-triggered moiety (nitrovanillin) and a cancer targeting unit (biotin). Upon light activation in cancer cells, PT-1 interferes with DNA re-ligation, diminishes the expression of topoisomerase I, and enhances the expression of inter alia mitochondrial apoptotic genes, death receptors, and caspase enzymes, inducing DNA damage and eventually leading to apoptosis. In vitro and in vivo studies showed significant inhibition of cancer growth and the hybrid system PT-1 thus shows promise as a programmed photo-therapeutic ("phototheranostic").
Bibliographical noteFunding Information:
This work was supported by The Ministry of Science, ICT & Future Planning (MSIP) of National Research Foundation of Korea (No. 2009-0081566 for JSK, No. 2012M3A9C7050139 for JHK, and No. 2015R1C1A1A02036905 for JH), Korea University Grant (for JH) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2013062997). Support for the work in Austin was provided by the National Institutes of Health (grant CA 68682 to JLS).
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