1. Endoplasmic reticulum stress promotes the release of exosomal PD-L1 from head and neck cancer cells and facilitates M2 macrophage polarization
- Author
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Yi Yuan, Pengfei Jiao, Zeyu Wang, Mengqi Chen, Hongming Du, Liang Xu, Juanyong Xu, Youjin Dai, Fu-gen Wu, Yaqin Zhang, and Heming Wu
- Subjects
Oral squamous cell carcinoma ,Macrophage ,Endoplasmic reticulum stress ,Exosome ,PD-L1 ,Medicine ,Cytology ,QH573-671 - Abstract
Abstract Background Endoplasmic reticulum (ER) stress has been found to foster the escape of cancer cells from immune surveillance and upregulate PD-L1 expression. However, the underlying mechanisms are unknown. Methods While analyzing the protein levels using immunofluorescence and Western blotting, the RNA levels were measured using qRT-PCR. Ten injection of exosomes into six-week-old nude mice was made through the tail vein once every other day in total. Results The expression of certain ER stress markers such as PERK (PKR-like endoplasmic reticulum kinase), ATF6 (activating transcription factor 6), and GRP78 (glucose-regulated protein 78), was found to be upregulated in the oral squamous cell carcinoma (OSCC) tissues and related to poor overall survival. There is a positive relationship between the extent of ER stress-related proteins and a cluster of PD-L1 expression and macrophage infiltration among the OSCC tissues. Further, incubation with exosomes derived from ER-stressed HN4 cells (Exo-ER) was found to upregulate PD-L1 extents in macrophages in vitro and in vivo, and macrophage polarization toward the M2 subtype was promoted by upregulating PD-L1. Conclusions ER stress causes OSCC cells to secrete exosomal PD-L1 and upregulates PD-L1 expression in macrophages to drive M2 macrophage polarization. The delineation of a new exosome-modulated mechanism was made for OSCC–macrophage crosstalk driving tumor development and to be examined for its therapeutic use. Graphical abstract Exosomal PD-L1 secreted by ER-stressed OSCC cells promoted M2 macrophage polarization. Video Abstract.
- Published
- 2022
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