Breast cancer is the most prevalent cancer among women worldwide, and is the second leading cause of cancer mortality among women. Triple-negative breast cancers (TNBCs; ER-/PR-/HER2-) are highly aggressive tumors with poor prognosis. Due to lack of these specific receptors, TNBCs cannot be treated with hormone therapies or anti-HER2 targeted therapies. Chemotherapy, combined with surgery and radiation therapy, is the primary strategy for treating TNBCs. Thus, discovery and evaluation of new alternative medications targeting triple-negative breast cancer is of tremendous importance for reducing breast cancer mortality. Isorhapontigenin (ISO), a new derivative of stilbene isolated from Chinese herb Gnetum Cleistostachyun, exhibits a strong inhibitory effect on human bladder cancers. However, its anticancer activity with respect to breast cancer remains unclear. In the present study, we investigated the potential anticancer effect of ISO on TNBCs. ISO treatment inhibited the proliferation and anchorage-independent growth of 4T1 cells, a murine triple-negative breast cancer cell line, in a dose-dependent manner. In addition, the results from wound healing and Transwell invasion assay indicated significantly reduced cell migration and invasion in ISO-treated cells. Moreover, we performed the whole transcriptome analysis using RNA-seq to elucidate the molecules and pathways that mediate ISO's anticancer activity. A total of 1972 differentially expressed genes were identified in ISO-treated cells. IPA analysis revealed that the top canonical pathway altered by ISO is NRF2-mediated pathway. ISO-induced NRF2 activation was further confirmed by nuclear translocation of NRF2 protein and upregulation of NRF2 downstream target genes (GSTA1, GSTM1, HMOX1, and NQO1). In summary, our study is the first to demonstrate that ISO inhibits breast cancer cell growth and invasion, in part, by activating NRF2-mediated signaling pathway. Our results provide a novel mechanism for ISO-induced anticancer effect, and strongly support ISO as a promising therapeutic agent for triple-negative breast cancers.

Citation Format: Yusha Zhu, Anthony Murphy, Thomas Kluz, Bo Li, Max Costa, Chuanshu Huang, Hong Sun. Isorhapontigenin inhibits triple-negative breast cancer via activating NRF2-mediated pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5857.