Melanoma-Derived Wnt5a Promotes Local Dendritic-Cell Expression of IDO and Immunotolerance: Opportunities for Pharmacologic Enhancement of Immunotherapy.


The β-catenin signaling pathway has been demonstrated to promote the development of a tolerogenic dendritic cell (DC) population capable of driving regulatory T-cell (Treg) differentiation. Further studies have implicated tolerogenic DCs in promoting carcinogenesis in preclinical models. The molecular mechanisms underlying the establishment of immune tolerance by this DC population are poorly understood, and the methods by which developing cancers can co-opt this pathway to subvert immune surveillance are currently unknown. This work demonstrates that melanoma-derived Wnt5a ligand upregulates the durable expression and activity of the indoleamine 2,3-dioxygenase-1 (IDO) enzyme by local DCs in a manner that depends upon the β-catenin signaling pathway. These data indicate that Wnt5a-conditioned DCs promote the differentiation of Tregs in an IDO-dependent manner, and that this process serves to suppress melanoma immune surveillance. We further show that the genetic silencing of the PORCN membrane-bound O-acyl transferase, which is necessary for melanoma Wnt ligand secretion, enhances antitumor T-cell immunity, and that the pharmacologic inhibition of this enzyme synergistically suppresses melanoma progression when combined with anti-CTLA-4 antibody therapy. Finally, our data suggest that β-catenin signaling activity, based on a target gene expression profile that includes IDO in human sentinel lymph node-derived DCs, is associated with melanoma disease burden and diminished progression-free survival. This work implicates the Wnt-β-catenin signaling pathway as a novel therapeutic target in the melanoma immune microenvironment and demonstrates the potential impact of manipulating DC function as a strategy for optimizing tumor immunotherapy.





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Publication Info

Holtzhausen, Alisha, Fei Zhao, Kathy S Evans, Masahito Tsutsui, Ciriana Orabona, Douglas S Tyler and Brent A Hanks (2015). Melanoma-Derived Wnt5a Promotes Local Dendritic-Cell Expression of IDO and Immunotolerance: Opportunities for Pharmacologic Enhancement of Immunotherapy. Cancer Immunol Res, 3(9). pp. 1082–1095. 10.1158/2326-6066.CIR-14-0167 Retrieved from

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Brent A. Hanks

Associate Professor of Medicine

We are interested in understanding the mechanisms that cancers have evolved to suppress the generation of tumor antigen-specific immune responses and how this knowledge can be exploited for the development of novel and more effective cancer immunotherapy strategies. This work involves the utilization of both autochthonous transgenic tumor model systems as well as clinical specimens to develop novel strategies to enhance the efficacy of immunotherapies while also developing predictive biomarkers to better guide the management of cancer patients with these agents. We strive to translate our understanding of the fundamental biochemical and metabolic pathways within the tumor microenvironment that are critical for driving immune evasion and resistance into early phase clinical trial testing.

Our work utilizes a variety of techniques and methodologies that span the breadth of basic biological research. This work integrates studies based on both 1) transgenic mouse tumor models that are monitored using bioluminescence and micro-CT imaging and 2) a variety of clinical specimens.

Our current areas of focus include:

  1. Investigating mechanisms of adaptive or acquired immunotherapy resistance in cancer
  2. Studying the relationship between EMT pathways and immunotherapy resistance.
  3. Elucidating mechanisms of dendritic cell tolerization in the tumor microenvironment and how these processes may contribute to immunotherapy resistance
  4. Development of novel pharmacologic and genetic strategies to overcome immunotherapy resistance
  5. Investigating mechanisms contributing to select immunotherapy-associated toxicities

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