Abstract 3944: MKI-1 is a small molecule inhibitor of MASTL with antitumor and radiosensitizer activity in breast cancer cells

Abstract

Abstract Although microtubule-associated serine threonine kinase like (MASTL) is an emerging target for selective anticancer treatment, a small-molecule inhibitor of MASTL with antitumor activity had not been reported yet. This study showed the new MASTL inhibitor, MKI 1 (MASTL Kinase Inhibitor 1), with antitumor activity and radiosensitizing effect in breast cancer in vitro and in vivo. MKI 1 was identified and validated its inhibitory activity to MASTL by in silico and in vitro analysis, respectively. MKI 1 inhibited phosphorylated ENSA, a direct substrate of MASTL, but not the other AGC kinases such as Akt signaling in breast cancer cells. In addition, MKI 1 reduced various oncogenic properties of breast cancer cells rather than normal breast cells. Furthermore, MKI 1 increased the radiosensitivity of breast cancer cells and breast cancer stem cells in response to irradiation. We also confirm the in vivo antitumor activity and radiosensitizing effects of MKI 1 in breast tumor xenograft model. Therefore, our results provide the new line of a small-molecule inhibitor of MASTL, MKI 1, with the antitumor and radiosensitizer activity in breast cancer in vitro and in vivo. Citation Format: Ah-Young Kim, Jae-Sung Kim. MKI-1 is a small molecule inhibitor of MASTL with antitumor and radiosensitizer activity in breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3944.