Zhu, Yini, Zhao, Yun, Wen, Jiling, Liu, Sheng, Huang, Tianhe, Hatial, Ishita, Peng, Xiaoxia, Al Janabi, Hawraa, Huang, Gang, Mittlesteadt, Jackson, Cheng, Michael, Bhardwaj, Atul, Ashfeld, Brandon L., Kao, Kenneth R., Maeda, Dean Y., Dai, Xing, Wiest, Olaf, Blagg, Brian S.J., Lu, Xuemin, and Cheng, Liang
The noninflamed microenvironment in prostate cancer represents a barrier to immunotherapy. Genetic alterations underlying cancer cell–intrinsic oncogenic signaling are increasingly appreciated for their role in shaping the immune landscape. Recently, we identified Pygopus 2 (PYGO2) as the driver oncogene for the amplicon at 1q21.3 in prostate cancer. Here, using transgenic mouse models of metastatic prostate adenocarcinoma, we found that Pygo2 deletion decelerated tumor progression, diminished metastases, and extended survival. Pygo2 loss augmented the activation and infiltration of cytotoxic T lymphocytes (CTLs) and sensitized tumor cells to T cell killing. Mechanistically, Pygo2 orchestrated a p53/Sp1/Kit/Ido1 signaling network to foster a microenvironment hostile to CTLs. Genetic or pharmacological inhibition of Pygo2 enhanced the antitumor efficacy of immunotherapies using immune checkpoint blockade (ICB), adoptive cell transfer, or agents inhibiting myeloid-derived suppressor cells. In human prostate cancer samples, Pygo2 expression was inversely correlated with the infiltration of CD8+ T cells. Analysis of the ICB clinical data showed association between high PYGO2 level and worse outcome. Together, our results highlight a potential path to improve immunotherapy using Pygo2-targeted therapy for advanced prostate cancer. Breaking down the barrier to prostate cancer immunotherapy: Prostate cancer is minimally responsive to most immunotherapy approaches due to poor tumor infiltration of lymphocytes. Using mouse models of prostate cancer, Zhu et al. found that cancer cell expression of the chromatin effector Pygo2 promotes immunotherapy resistance by restraining tumor T cell infiltration and cytotoxicity. Pygo2's suppressive effects were mediated by promoting expression of the receptor tyrosine kinase Kit and activity of indoleamine 2,3-dioxygenase 1, which occurred independently of Wnt/β-catenin signaling. Genetic deletion or pharmacological inhibition of Pygo2 enhanced prostate tumor responses to a wide range of immunotherapies including adoptive T cell therapy, CXCR2 blockade, and PD-1/CTLA-4 immune checkpoint blockade. Together, these results demonstrate that Pygo2 regulates cancer cell-extrinsic immune features and represents a potential target for reducing prostate cancer resistance to immunotherapy. —CO [ABSTRACT FROM AUTHOR]