Abstract P131: The role of UDP-6 glucose dehydrogenase (UGDH) in estrogen-mediated phenotypes in both estrogen receptor positive and estrogen receptor negative breast cancer

A better understanding of pathologic mechanisms underlying breast cancer progression and metastasis is critical to improve current treatment modalities. UDP-6- glucose dehydrogenase (UGDH) is an enzyme that has become a recent oncologic target of interest across various cancer subtypes for its role in increasing the aggressiveness and migratory capacity of tumor cells both in vitro and in vivo. UGDH is ubiquitously expressed and plays a critical role in forming the extracellular matrix (ECM), producing nucleotide sugars, and processing hormones through glucuronidation. For these reasons, investigating the effect of UGDH on breast cancer in the setting of hormonal stimulation is important. We found that knocking down UGDH in estrogen receptor positive (ER+) breast cancer cell lines (MCF7 marco and T47D) and an estrogen receptor negative (ER-) breast cancer cell line (MDA-MB-231) could abrogate estrogen induced migration-specific phenotypes in vitro. Furthermore, we found that knocking down UGDH mitigated estrogen stimulated primary tumor growth in vivo for both MCF7 macro and MDA-MB-231 mammary fat pad tumor models in mice. Thus, we found that UGDH regulates estrogen stimulated migratory phenotypes in both ER+ and ER- breast cancers in vitro and primary tumor growth in vivo. For this reason, UGDH and its associated pathways are promising targets for future drug development and small molecular targets in the treatment of both metastatic ER positive and ER negative breast cancers.

Citation Format: Meghan Price, Catherine Lavau, Cesar Baeta, Jovita Byemerwa, Suzanne Wardell, Olivia Brueckner, Debarati Mukherjee, Corinne Haynes, Annee Nguyen, Chingyi Chang, Donald McDonnell, C. Rory Goodwin. The role of UDP-6 glucose dehydrogenase (UGDH) in estrogen-mediated phenotypes in both estrogen receptor positive and estrogen receptor negative breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P131.

Inhibition of estrogen signaling in myeloid cells increases tumor immunity in melanoma

Immune checkpoint blockade (ICB) therapies have significantly prolonged patient survival across multiple tumor types, particularly in melanoma. Interestingly, sex-specific differences in response to ICB have been observed, with males receiving a greater benefit from ICB than females, although the mechanism or mechanisms underlying this difference are unknown. Mining published transcriptomic data sets, we determined that the response to ICBs is influenced by the functionality of intratumoral macrophages. This puts into context our observation that estrogens (E2) working through the estrogen receptor α (ERα) stimulated melanoma growth in murine models by skewing macrophage polarization toward an immune-suppressive state that promoted CD8+ T cell dysfunction and exhaustion and ICB resistance. This activity was not evident in mice harboring macrophage-specific depletion of ERα, confirming a direct role for estrogen signaling within myeloid cells in establishing an immunosuppressed state. Inhibition of ERα using fulvestrant, a selective estrogen receptor downregulator (SERD), decreased tumor growth, stimulated adaptive immunity, and increased the antitumor efficacy of ICBs. Further, a gene signature that determines ER activity in macrophages predicted survival in patients with melanoma treated with ICB. These results highlight the importance of E2/ER signaling as a regulator of intratumoral macrophage polarization, an activity that can be therapeutically targeted to reverse immune suppression and increase ICB efficacy.