ATR senses stiff extracellular matrix to promote epithelial-to-mesenchymal transition and immune suppression
Xinyi Tu, Xiangyu Zeng, Yaoliang Sun, Yaobin Ouyang, Lingling Zhu, Ping Yin, Kevin Pavelko, Roberto Leon-Ferre, Yanxia Jiang, Haidong Dong, Jodi Carter, Shouhai Zhu, Jann N. Sarkaria, Liewei Wang, Jinzhou Huang, Kuntian Luo, Yiqun Han, Zheming Wu, Zhenkun Lou, Robert W. Mutter
Xinyi Tu, Xiangyu Zeng, Yaoliang Sun, Yaobin Ouyang, Lingling Zhu, Ping Yin, Kevin Pavelko, Roberto Leon-Ferre, Yanxia Jiang, Haidong Dong, Jodi Carter, Shouhai Zhu, Jann N. Sarkaria, Liewei Wang, Jinzhou Huang, Kuntian Luo, Yiqun Han, Zheming Wu, Zhenkun Lou, Robert W. Mutter
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Research Article Cell biology Immunology Oncology

ATR senses stiff extracellular matrix to promote epithelial-to-mesenchymal transition and immune suppression

Abstract

Our research uncovers a role for ATR in responding to ECM stiffness and promoting epithelial-to-mesenchymal transition (EMT) and metastasis. ATR, when deubiquitinated and upregulated by USP21 under enhanced ECM stiffness conditions, phosphorylates the nuclear protein SUN2, which promotes β-catenin nuclear translocation and EMT. ATM-mediated EMT promotes polymorphonuclear myeloid-derived suppressor cell recruitment and inhibits CD103+ dendritic cells, fostering an immunosuppressive tumor milieu. ATR inhibition disrupts this malignant cascade by promoting mesenchymal-to-epithelial transition to enhance antitumor immunity and mitigate metastases. Consistently, circulating HLA-DR+ dendritic cells were also enhanced following treatment with the ATR inhibitor berzosertib in patients with therapeutically resistant early-stage breast cancer. Our data suggest that ATR-targeted therapy may be optimized by considering both DNA damage–dependent and EMT-inducing effects of ATR

Authors

Xinyi Tu, Xiangyu Zeng, Yaoliang Sun, Yaobin Ouyang, Lingling Zhu, Ping Yin, Kevin Pavelko, Roberto Leon-Ferre, Yanxia Jiang, Haidong Dong, Jodi Carter, Shouhai Zhu, Jann N. Sarkaria, Liewei Wang, Jinzhou Huang, Kuntian Luo, Yiqun Han, Zheming Wu, Zhenkun Lou, Robert W. Mutter

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Figure 1

ECM stiffness induces ATR expression through USP21.

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ECM stiffness induces ATR expression through USP21. (A and B) Tumors wer...
(A and B) Tumors were harvested from 36 TNBC patients and processed to create FFPE blocks. These blocks were then sectioned and subjected to IHC analysis. ATR IHC analysis of 36 TNBC primary tumor samples and their adjacent normal tissues are shown. Statistical significance was determined using 2-tailed Student’s t test (P < 0.0001). Scale bars: 1 mm (left), 100 μm (right). (C and D) IHC analysis of 34 TNBC primary tumor samples staining with ATR and 2 fibrosis markers, α-SMA and COL1A1. The results, quantified as integrated optical density, revealed a positive correlation between the level of ATR and the 2 fibrosis markers. Pearson’s correlation analysis showed that ATR expression was positively correlated with α-SMA expression (r = 0.5593, P = 0.0006) and COL1A1 expression (r = 0.4599, P = 0.0062). (E) The expression of the indicated proteins in MDA-MB-231 cells cultured on surfaces with varying stiffness was analyzed by Western blotting. Actin served as a loading control. (F) Statistical analysis of the Western blot results in E by 1-way ANOVA (n = 3). (G) MCF-10A cells were cultured on substrates with different stiffnesses for 48 hours, after which ATR expression was assessed by immunofluorescence. Statistical significance was determined using 1-way ANOVA (n = 3). Original magnification, ×20. (H) MDA-MB-231 cells transfected with control or USP21-targeted siRNA were cultured on surfaces with indicated stiffness for 48 hours. USP21 and ATR expression levels were then determined. (I) Statistical analysis of the Western blot results in H by 2-way ANOVA (n = 3). Data are presented as mean ± SD.