Abstract 2573: Investigation of factors involved in the hypersensitivity to KP1339-treatment

Abstract

The ruthenium-based compound KP1339 (trans-(tetrachlorobis(1H-indazole)ruthenate(III)), which is currently in Phase I/II trial, is already known for its promising anticancer activity. In course of a recent screening using diverse cancer cell lines of different origin (n = 25), a small subgroup with exceptional sensitivity to KP1339-treatment was discovered. The aim of the here presented study was to identify factors that underlie this sensitivity or which are connected to resistance to KP1339. Due to the fact that KP1339 comprises a metal center, interpretations of it's mode of action tend towards either generation of ROS or DNA binding. To avoid a biased approach, whole genome expression arrays were performed with mRNA isolated from hypersensitive and normal responsive cells that were either untreated or treated with KP1339 for 3 h and 6 h. Subsequent bioinformatic analysis of the gained data indicated that while hypersensitive cell lines activated pathways indicative for response to chemical stimuli (“metal ion”, “organic compound”), in normal responsive ones preferentially genes involved in pathways controlling cell cycle, DNA repair and metabolism were found. Subsequent investigations confirmed that upon KP1339-treatment hypersensitive cell lines showed pronounced apoptosis induction (indicated by caspase-mediated PARP cleavage and appearance of apoptotic nuclei visualized by DAPI staining). In contrast, normal responsive cells rather reacted with prolonged duration of the G2 phase to KP1339 treatment (video evaluation). This was confirmed by FACS analysis of ethanol-fixed and propidium iodide-stained cells indicating a profound increase in the percentage of cells with double DNA content upon KP1339 treatment. Moreover, in accordance to previous studies, KP1339 induced strong phosphorylation of ERK, p38 and JNK especially in normal responsive cell lines. This is of interest as p38 and JNK activation are known to be pro-survival factors within the extrinsic pathway of apoptosis. The relevance of this particular pathway is supported by preliminary results of activation of caspase 8 upon KP1339 treatment in hypersensitive cells. This knowledge can help to better understand the mechanisms underlying the promising anticancer activity of KP1339.

Citation Format: Beatrix Alte, Christine Pirker, Thomas Mohr, Kushtrim Kryeziu, Bernhard K. Keppler, Petra Heffeter, Walter Berger. Investigation of factors involved in the hypersensitivity to KP1339-treatment. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2573. doi:10.1158/1538-7445.AM2015-2573