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Theranostics 2021; 11(5):2364-2380. doi:10.7150/thno.47996 This issue Cite

Research Paper

Endocytic pathway inhibition attenuates extracellular vesicle-induced reduction of chemosensitivity to bortezomib in multiple myeloma cells

Chenggong Tu^1,2#, Zhimin Du^3#, Hui Zhang^1,2#, Yueyuan Feng^1,2, Yujun Qi⁴, Yongjiang Zheng⁵, Jinbao Liu^1,2✉, Jinheng Wang^1,2✉

1. Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou 510095, China
2. Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation; State Key Laboratory of Respiratory Disease; School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou 511436, China
3. School of Nursing, Guangzhou Medical University, Guangzhou 510182, China
4. Zhengzhou University School of Medicine, Zhengzhou 450052, China
5. Department of Hematology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510630, China
^# These authors contributed equally to this work.

✉ Corresponding authors: Prof. Jinheng Wang, E-mail: wangjh89edu.cn. Prof. Jinbao Liu, E-mail: jliuedu.cn. Address: Affiliated Cancer Hospital & Institute of Guangzhou Medical University; Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation; State Key Laboratory of Respiratory Disease; School of Basic Medical Sciences, Guangzhou Medical University, 510095, Guangzhou, China. Tel/Tax: +86 020-37103060 More

Abstract

Extracellular vesicles (EVs), including exosomes and microvesicles, derived from bone marrow stromal cells (BMSCs) have been demonstrated as key factors in the progression and drug resistance of multiple myeloma (MM). EV uptake involves a variety of mechanisms which largely depend on the vesicle origin and recipient cell type. The aim of the present study was to identify the mechanisms involved in the uptake of BMSC-derived small EVs (sEVs) by MM cells, and to evaluate the anti-MM effect of targeting this process.

Methods: Human BMSC-derived sEVs were identified by transmission electron microscopy, nanoparticle tracking analysis, and western blot. The effects of chemical inhibitors and shRNA-mediated knockdown of endocytosis-associated genes on sEV uptake and cell apoptosis were analyzed by flow cytometry. The anti-MM effect of blocking sEV uptake was evaluated in vitro and in a xenograft MM mouse model.

Results: sEVs derived from BMSC were taken up by MM cells in a time- and dose-dependent manner, and subsequently promoted MM cell cycling and reduced their chemosensitivity to bortezomib. Chemical endocytosis inhibitors targeting heparin sulphate proteoglycans, actin, tyrosine kinase, dynamin-2, sodium/proton exchangers, or phosphoinositide 3-kinases significantly reduced MM cell internalization of BMSC-derived sEVs. Moreover, shRNA-mediated knockdown of endocytosis-associated proteins, including caveolin-1, flotillin-1, clathrin heavy chain, and dynamin-2 in MM cells suppressed sEV uptake. Furthermore, an endocytosis inhibitor targeting dynamin-2 preferentially suppressed the uptake of sEV by primary MM cells ex vivo and enhanced the anti-MM effects of bortezomib in vitro and in a mouse model.

Conclusion: Clathrin- and caveolin-dependent endocytosis and macropinocytosis are the predominant routes of sEV-mediated communication between BMSCs and MM cells, and inhibiting endocytosis attenuates sEV-induced reduction of chemosensitivity to bortezomib, and thus enhances its anti-MM properties.

Keywords: extracellular vesicles, exosomes, multiple myeloma, endocytosis, chemosensitivity

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