Abstract B25: Novel regulation and function of Dishevelled 2 in the tumor microenvironment

Abstract Background: The Wnt/β-catenin pathway contributes to tumorigenesis and recently has been shown to modulate T cell infiltration into the tumor microenvironment (TME). Dishevelled paralogs (DVL1-3) are key mediators of β-catenin dependent and independent Wnt signaling. Though DVL proteins are significant drivers of oncogenic Wnt signaling, little is known about their post-translational regulation and its impacts on tumor immunity. We aimed to study novel DVL post translational modifications (PTMs) and their influence on transcription and epigenetic regulation of immune associated genes in breast cancer (BC). Previous DVL1/3 ChIP-seq analyses revealed that other DVL paralogs bind to genes in tumor cells that modulate immune cell function. We hypothesize that tumor-intrinsic DVL2 regulates the expression of immunomodulatory genes. We further hypothesize that our recently discovered DVL PTMs will impact DVL function and immune cell infiltration into the TME. Experimental design: The cancer genome atlas (TCGA) database was mined for DVL2 expression in BC patients. To determine DVL2 localization to promoters of immune associated genes across a panel of BC cells, DVL2 ChIP-PCR was performed. To determine whether DVL2 was a positive or negative regulator of these genes, RT-qPCR was performed in BC cells in which DVL2 was stably depleted via shRNA. Finally, to identify novel DVL2 post-translational modification, immunoprecipitation and LC-MS/MS were performed.Result: TCGA analyses suggested a significant positive correlation between high DVL2 expression and poor overall and metastasis free survival in BC patients. DVL2 ChIP-PCR analyses showed that DVL2 binds to genes involved in antigen presentation and TIL recruitment. Moreover, RT-qPCR analyses revealed that DVL2 regulates mRNA expression of genes that modulate immune cell function, and Wnt target genes that impact cell proliferation, angiogenesis, and invasion. Interestingly, we have identified novel DVL2 PTMs from proteomic analyses and investigated its impact on genes involved in BC tumor immunity.Summary: Our study examines the novel biology of DVL2 and shows its aberrant expression in BC. We also show for the first time that DVL2 binds to gene promoters and regulates the expression of targets that influence TIL recruitment to the tumor microenvironment. A deeper understanding of DVL2 biology in BC tumors may lead to the development of novel therapeutic strategies. Citation Format: Geetha P Boligala, Dalia Martinez-Marin, Michael W Melkus, Rakhshanda Layeequr Rahman, Kevin Pruitt. Novel regulation and function of Dishevelled 2 in the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr B25.