Abstract 2925: WAVE3 is associated with chemoresistance in TNBC by activating tumor angiogenesis downstream of the STAT1/Hif-1α/VEGF-A signaling axis

Abstract

Abstract Chemoresistance is the main cause of disease recurrence and eventual death of breast cancer patients, particularly those harboring triple-negative breast cancer (TNBC) tumors for which effective FDA-approved drugs currently do not exist. However, a recent study determined that TNBCs can be segregated into 6 genetically distinct subtypes that do in fact exhibit differential rates of pathological complete response (pCR) to standard-of-care chemotherapies. Interestingly, the mesenchymal and mesenchymal stem-like subtypes of TNBCs exhibit the lowest rates of pCR when treated with standard-of-care chemotherapies. WAVE3 is an actin-cytoskeleton remodeling protein, and recent studies have highlighted a potential role for WAVE3 in promoting tumor progression and metastasis in TNBC. However, whether WAVE3 activity is involved in the development of chemoresistance in TNBCs, remains unclear. Here we show that loss of WAVE3 expression resensitizes human TNBC cells to Doxorubicin and Docetaxel, as measured by increased apoptosis and cell death. We also show that WAVE3 knockdown in the chemotherapy-treated TNBC cells results in inhibition of STAT1 phosphorylation, as well as a significant decrease in expression levels of its downstream effector Hif-1α. Since Hif-1α is a major activator of VEGF-A production, and therefore, a stimulator of tumor angiogenesis, loss of Hif-1α in the WAVE3-knocdown cells resulted in the inhibition the chemotherapy-mediated VEGF-A secretion and the downstream activation of angiogenesis, a phenomenon that often accompanies chemoresistance. Our data identify a critical role of WAVE3 in sensitizing TNBC to chemotherapy by inhibiting the STAT1⌠Hif-1α⌠VEGF-A signaling axis, and support the possibility of WAVE3 inhibition as a promising approach for TNBC cancer therapy. Citation Format: Gangarao Davuluri, Edward F. Plow, William P. Schiemann, Khalid Sossey-Alaoui. WAVE3 is associated with chemoresistance in TNBC by activating tumor angiogenesis downstream of the STAT1/Hif-1α/VEGF-A signaling axis. [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 2925. doi:10.1158/1538-7445.AM2015-2925