Abstract 5100: AB61, a new potent nucleoside cytostatic: Molecular mechanisms of action and preclinical activity

7-(2-Thienyl)-7-deazaadenosine (AB61) showed nanomolar cytotoxic activities against various cancer cell lines but only mild (micromolar) activities against normal fibroblasts. The selectivity of AB61 was found to be due to inefficient phosphorylation of AB61 in normal fibroblasts. The phosphorylation of AB61 in the leukemic CCRF-CEM cell line proceeds well and it was shown that AB61 is incorporated into both DNA and RNA, preferentially as a ribonucleotide. It was further confirmed that a triphosphate of AB61 is a substrate for both RNA and DNA polymerases in enzymatic assays. Gene expression analysis suggests that AB61 affects DNA damage pathways and protein translation/folding machinery. Indeed, the formation of large 53BP1 foci was observed in nuclei of AB61-treated U2OS-GFP-53BP1 cells indicating DNA damage. Random incorporation of AB61 into RNA blocked its translation in an in vitro assay and reduction of reporter protein expression was also observed in mice after 4-hour treatment with AB61. AB61 also significantly reduced tumor volume in mice bearing SK- OV-3, BT-549, HT-29 and MDA-MB231 xenografts. The results indicate that AB61 is a promising compound with the unique mechanism of action and deserves further development as an anticancer agent. This work was supported by the Ministry of Education of the Czech Republic (LO1304). Citation Format: Petr Dzubak, Marian Hajduch, Pavla Perlikova, Gabriela Rylová, Petr Naus, Tomas Elbert, Eva Tloustova, Aurelie Bourderioux, Lenka Slavetinska, Kamil Motyka, Dalibor Dolezal, Pawel Znojek, Alice Nova, Monika Harvanova, Michal Siler, Jan Hlavac, Michal Hocek. AB61, a new potent nucleoside cytostatic: Molecular mechanisms of action and preclinical activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5100. doi:10.1158/1538-7445.AM2017-5100