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Theranostics 2023; 13(1):59-76. doi:10.7150/thno.77313 This issue Cite

Research Paper

Stiff matrix induced srGAP2 tension gradients control migration direction in triple-negative breast cancer

Chen Li^1,2*, Zihui Zheng^1,2*, Xiang Wu^1,2,3, Qiu Xie^1,2, Ping Liu⁴, Yunfeng Hu^1,2, Mei Chen⁵, Liming Liu^1,2, Wangxing Zhao^1,2, Linlin Chen^1,2, Jun Guo^1,2✉, Ying Song^6✉

1. School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, Jiangsu, PR China.
2. Key Laboratory of Drug Target and Drug for Degenerative Disease, Nanjing University of Chinese Medicine, Nanjing 210023, Jiangsu, PR China.
3. Department of Anesthesiology, The Affiliated Hospital of Medical School, Ningbo University, Ningbo, 315040, PR China.
4. Department of Respiratory and Critical Care Medicine, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou 213003, People's Republic of China.
5. Department of Pathology, Xuzhou Central Hospital, Xuzhou 221009, PR China.
6. Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
*These authors contributed equally to this work.

✉ Corresponding authors: Jun Guo, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, 138 Xianlin Road, Qixia District, Nanjing 210023, Jiangsu, China. E-mail: guojedu.cn; Dr Ying Song, Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Gulou District, Nanjing 210029, China. E-mail: songzhang_yingcom. More

Abstract

Rationale: Cells migrating through interstitial matrix enables stiffening of the tumor micro-environment. To overcome the stiff resistance of extracellular matrix, aggressive cells require the extracellular mechanosensory activation and intracellular tension response. Mechanotransduction linker srGAP2 can synergistically control the mechanical-biochemical process of malignant cell migration.

Methods: To mimic the tumor micro-environment containing abundant collagen fibers and moving durotaxis of triple-negative breast cancer cells, the stiff-directed matrix was established. The newly designed srGAP2 tension probe was used to real-time supervise srGAP2 tension in living cells. The phosphorylation sites responsible for srGAP2 tension were identified by phosphorylated mutagenesis. Transwell assays and Xenograft mouse model were performed to evaluate TNBC cells invasiveness in vitro and in vivo. Fluorescence staining and membrane protein isolation were used to detect protein localization.

Results: The present study shows srGAP2 serves as a linker to transmit the mechanical signals among cytoskeleton and membrane. SrGAP2 exhibits tension gradients among different parts in the stiff-directionally migrating triple-negative breast cancer cells. Cells showing the polarized tension that increased in the leading edge move faster, particularly guided by the stiff interstitial matrix. The srGAP2 tension-directed cell migration results from the upstream events of PKCα-mediated phosphorylation at Ser²⁰⁶ in the F-bar domain of srGAP2. In addition, Syndecan-4 (SDC4), a transmembrane mechanoreceptor protein, drives PKCα regional recruit on the area of membrane trending deformation, which requires the distinct extent of extracellular mechanics.

Conclusion: SDC4-PKCα polarized distribution leads to the intracellular tension gradient of srGAP2, presenting the extra- and intracellular physiochemical integration and essential for persistent cell migration in stiff matrix and caner progression. Targeting the srGAP2-related physicochemical signaling could be developed into the therapeutic strategies of inhibiting breast cancer cell invasion and durotaxis.

Keywords: srGAP2, polarized tension, stiff-directed migration, FRET, syndecan-4

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