核心的Hippo通路模块由一个抑制转录的共激活因子Yes-associated protein (YAP)和WW domain-containing transcription regulator protein 1 (WWTR1;也称为TAZ)的肿瘤抑制激酶级联组成。当Hippo通路被下调，类似乳腺癌中那样，YAP/TAZ的活性将被诱导。为了进一步阐明TAZ在三阴性乳腺癌（TNBC）中的作用，我们使用CRISPR/Cas9技术或小发夹RNA (shRNA)在小鼠TNBC 4T1细胞中敲除了TAZ。TAZ敲除细胞及其保留了野生型TAZ水平的对照细胞被正位注射到同种异基因BALB/c雌性小鼠的乳脂肪垫中，并监测其肿瘤生长。与对照细胞产生的肿瘤相比，TAZ缺失导致较小的肿瘤，符合TAZ在乳腺癌中作为一个癌基因的观点。然后，利用RNA测序（RNA-seq）对肿瘤及其相应的离体培养细胞进行了基因表达谱分析。有趣的是，RNA-seq数据的通路分析表明，在TAZ依赖的情况下，“炎症反应”通路丰度增加，这一现象也与乳腺癌患者中TAZ表达相关。具体来说，RNA-seq分析预测TAZ缺失肿瘤中调节性T细胞（Tregs）的明显减少，这一结果通过肿瘤切片染色和质谱流式细胞分析进行了实验验证。令人惊讶的是，在免疫缺陷小鼠中肿瘤大小的差异完全消失，这表明TAZ的免疫调节能力在该环境中对其致癌活性至关重要。细胞培养液的细胞因子芯片分析显示，与对照组相比，TAZ增加了一组细胞因子的丰度，包括纤溶酶原激活抑制剂1(也称为PAI-1)、CCN家族成员4(也称为WISP-1)和白细胞介素23（IL-23），推测这可能是TAZ在体内免疫调节作用的一种机制解释。总之，我们的结果表明TAZ以一种非细胞自主的方式调整肿瘤的免疫微环境，并削弱抗肿瘤免疫应答，从而促进肿瘤生长。本文受版权保护，版权所有。

The core Hippo pathway module consists of a tumor-suppressive kinase cascade that inhibits the transcriptional coactivators Yes-associated protein (YAP) and WW domain-containing transcription regulator protein 1 (WWTR1; also known as TAZ). When the Hippo pathway is downregulated, as often occurs in breast cancer, YAP/TAZ activity is induced. To elaborate the roles of TAZ in triple-negative breast cancer (TNBC), we depleted Taz in murine TNBC 4T1 cells, using either CRISPR/Cas9 or small hairpin RNA (shRNA). TAZ-depleted cells and their controls, harboring wild-type levels of TAZ, were orthotopically injected into the mammary fat pads of syngeneic BALB/c female mice, and mice were monitored for tumor growth. TAZ depletion resulted in smaller tumors compared to the tumors generated by control cells, in line with the notion that TAZ functions as an oncogene in breast cancer. Tumors, as well as their corresponding in vitro cultured cells, were then subjected to gene expression profiling by RNA sequencing (RNA-seq). Interestingly, pathway analysis of the RNA-seq data indicated a TAZ-dependent enrichment of 'Inflammatory Response', a pathway correlated with TAZ expression levels also in human breast cancer tumors. Specifically, the RNA-seq analysis predicted a significant depletion of regulatory T cells (Tregs) in TAZ-deficient tumors, which was experimentally validated by the staining of tumor sections and by quantitative cytometry by time of flight (CyTOF). Strikingly, the differences in tumor size were completely abolished in immune-deficient mice, demonstrating that the immune-modulatory capacity of TAZ is critical for its oncogenic activity in this setting. Cytokine array analysis of conditioned medium from cultured cells revealed that TAZ increased the abundance of a small group of cytokines, including plasminogen activator inhibitor 1 (Serpin E1; also known as PAI-1), CCN family member 4 (CCN4; also known as WISP-1) and interleukin-23 (IL-23), suggesting a potential mechanistic explanation for its in vivo immunomodulatory effect. Together, our results imply that TAZ functions in a non-cell-autonomous manner to modify the tumor immune microenvironment and dampen the anti-tumor immune response, thereby facilitating tumor growth.This article is protected by copyright. All rights reserved.