Abstract 4847: Dishevelled 2: A key regulator of tumor immunity in breast cancer

Breast cancer (BC) is the most frequently diagnosed and the leading cause of cancer related deaths among women worldwide. Despite advances in therapeutic strategies, the heterogeneity of BC poses significant challenge for effective treatment, particularly in aggressive subtypes such as triple-negative breast cancer (TNBC). Aberrant Wnt signaling plays a pivotal role in breast tumorigenesis from immunosuppression and reduced tumor infiltrating lymphocytes (TIL) activity to modulating various cancer hallmarks. Dishevelled (DVL1, 2, 3) proteins mediate both canonical and non-canonical Wnt signaling and are crucial for maintaining constitutive oncogenic Wnt signaling. Previous studies have demonstrated that DVL2 regulates the transcription of various immunomodulatory genes and DVL2 expression in HER2+ patient tissues show a negative correlation relative to CD8α levels. However, the molecular mechanism of how DVL2 modulates tumor immunity remains poorly understood. We hypothesize that DVL proteins serve as a critical link between aberrant Wnt signaling and impaired anti-tumor immunity in BC. To test this, we generated DVL2 knockout (K/O) models in two mouse mammary carcinoma cell lines, 4T1 and EO771, using CRISPR-Cas9. Non-targeting controls (NTC) were used as controls. 4T1 DVL2 K/O and NTC cells were injected into BALB/c mice, while EO771 DVL2 K/O and NTC cells were injected into C57BL/6 mice. Tumor volume was monitored for three weeks, after which mice were sacrificed, and tumors and tumor-draining lymph nodes were collected for analysis. RT-qPCR, western blotting, and flow cytometry were used to measure immune markers, while bulk RNA sequencing was performed to identify differences in immune gene signatures between DVL2 K/O and NTC tumors. RT-qPCR and western blotting revealed changes in the expression of classical Wnt markers involved in cell proliferation and migration following DVL2 knockout. Flow cytometry analysis demonstrated that DVL2 K/O significantly altered the frequency of T lymphocytes, including activated and effector memory CD8+ T cells, CD4+ T cells, and natural killer T (NKT) cells. The frequency of cytotoxic innate lymphocytes, such as NK cells, was also significantly affected. RNA-seq analysis further highlighted alterations in multiple immune pathways in DVL2 K/O tumors compared to NTC tumors. These findings suggest that DVL2 plays a pivotal role in modulating tumor immunity by influencing both adaptive and innate immune cell populations. This study underscores the importance of DVL proteins as a potential therapeutic target in breast cancer. Citation Format: Geetha P. Boligala, Grace Stroman, Rachel L. Babcock, Dalia Martinez-Marin, Flavia Sardela de Miranda, Ella C. Jull, Michael W. Melkus, Kevin Pruitt. Dishevelled 2: A key regulator of tumor immunity in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4847.