Abstract A051: Targeting notch signaling pathway with auranofin for endometrial cancer therapy

The Notch signaling pathway regulates cell proliferation and differentiation. Aberrant Notch activation contributes to cancer initiation, proliferation, and chemoresistance. Endometrial cancer (EC) is the most common gynecologic cancer, with increasing incidence and mortality rates in the USA. While survival rates for early-stage EC are high, advanced and recurrent ECs are difficult to treat, with a five-year survival rate of less than 20%. Therefore, there is a critical need to develop novel treatment options. Data from The Cancer Genome Atlas indicates that EC patients with increased copy numbers of Notch2 or Notch3 have lower survival rates. Conversely, patients with somatic mutations in Notch2 and Notch3 have better prognosis, supporting the hypothesis of targeting Notch in EC therapy. However, efforts to inhibit Notch signaling in cancer therapy have been hampered by off-target toxicities. We have identified an FDA-approved drug, auranofin, as a novel Notch pathway inhibitor that prevents the major downstream transcription effector, RBPJ, from binding to Notch targets, thereby inhibiting Notch-dependent transcriptional activation. Using chromatin immunoprecipitation followed by qPCR, we further demonstrated that auranofin inhibits RBPJ-DNA interactions in EC cells in a dose-dependent manner at the Notch-dependent HES1 and HES4 promoters but not at the Notch-independent CDKN1A promoter. This supports the notion that auranofin inhibits Notch signaling in EC cells. Using shRNA targeting Notch 3, I found that the EC cell line AN3CA requires Notch signaling for viability, in contrast to KLE cells. Additionally, we found that auranofin synergizes with cisplatin in killing AN3CA cells but not KLE cells in 2D cultures. Strikingly, using an AN3CA-derived xenograft mouse model, we further observed that auranofin enhances cisplatin efficacy in reducing tumor growth. Together, these results underscore the potential of auranofin in improving cisplatin efficacy for EC therapy, particularly in Notch-dependent tumors. Citation Format: Cynthia M. Tshibangu, Robert J. Lake, Mara P. Steinkamp, Hua-Ying Fan. Targeting notch signaling pathway with auranofin for endometrial cancer therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr A051.