Hippo/YAP signaling choreographs the tumor immune microenvironment to promote triple negative breast cancer progression via TAZ/IL-34 axis.

Growing evidence suggests that the bidirectional interactions between cancer cells and their surrounding environment, namely the tumor microenvironment (TME), contribute to cancer progression, metastasis, and resistance to treatment. Intense investigation of the Hippo pathway, which controls multiple central cellular functions in tumorigenesis, was focused on cancer cells. However, the role of the Hippo pathway in modulating tumor-stromal interactions in triple-negative breast cancer remains largely unknown. Therefore, this study focused on revealing the effects of Hippo-YAP/TAZ signaling on the immune microenvironment. Our findings reveal that the activity of the Hippo pathway is associated with worse disease outcomes in TNBC and could increase TAM infiltration through the TAZ/IL-34 axis, leading to an immunosuppressive microenvironment and impairing the treatment efficacy of anti-PD-L1. Thus, the TAZ/IL-34 axis may serve as a novel target for TNBC patients.