Abstract 5482: Natural product inhibitor of Stat3, G6PD, and TrxR1 functions induces an early oxidative stress and pyroptosis, and a late-stage DNA damage and cell cycle arrest to block tumor growth in human breast cancer models

Abstract

Bioactive natural products have led to new drugs or been the inspiration for developing new treatments. Signal transducer and activator of transcription (STAT)3 is a an oncogene that has been implicated in many human cancers. We report that the hirsutinolide natural product, R001, blocks STAT3 DNA-binding activty in vitro. Treatment with R001 of the human triple-negative breast cancer (TNBC) cells, MDA-MB-231 and MDA-MB-468 led to the concurrent inhibition of constitutively-active STAT3 and the expression and activities of glucose-6-phosphate 1-dehydrogenase (G6PD) and thioredoxin reductase (TrxR)1, early suppression of glutathione (GSH), and the induction of reactive oxygen species (ROS), which peaked at 6-24 h post R001-treatment. In the short term, R001-treated TNBC cells showed evidence of pyroptotic cell death. Prolonged treatment of TNBC cells with R001 led to DNA damage and G2/M-phase cell cycle arrest, which are late-stage responses that were preceded by the suppression of ATM-Chk2-Cdc25c pathway, and the induction of p21 and γH2AX phosphorylation by the natural product. Accordingly, R001 suppressed the viable cell numbers, colony formation, growth in 3D-matrigel, and the migration of MDA-MB-231 and MDA-MB-468 cells in vitro. The oral administration of R001 at 5 mg/kg signficantly inhibited growth of human MDA-MB-468 xenografts in mice. Results together show that R001 inhibits STAT3, G6PD and TrxR1 functions that lead to early oxidative stress and pyroptosis and late-stage DNA damage and cell cycle arrest, which collectively cause tumor cell death and tumor growth inhibition in human TNBC models. Citation Format: Yinsong Zhu, Cody F. Dickinson, Justin Yang, Kyrstin Datanagan, Ning Zhai, Peibin Yue, Francisco Lopez-Tapia, Marcus A. Tius, James Turkson. Natural product inhibitor of Stat3, G6PD, and TrxR1 functions induces an early oxidative stress and pyroptosis, and a late-stage DNA damage and cell cycle arrest to block tumor growth in human breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5482.