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Background: Myeloid-derived suppressor cells (MDSCs) are the major factor in gastric cancer (GC) immune evasion. Nevertheless, the molecular process underlying the expansion of MDSCs induced by tumor-derived exosomes (TDEs) remains elusive., Methods: The levels of exosomal and soluble PD-L1 in ninety GC patients were examined via enzyme-linked immunosorbent assay (ELISA) to determine their prognostic value. To investigate the correlation between exosomal PD-L1 and MDSCs, the percentage of MDSCs in the peripheral blood of 57 GC patients was assessed via flow cytometry. Through ultracentrifugation, the exosomes were separated from the GC cell supernatant and detected via Western blotting, nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM). The function of exosomal PD-L1 in MDSCs was evaluated via immunofluorescence, Western blotting and flow cytometry in a GC cell-derived xenograft (CDX) model., Results: The overall survival (OS) of GC patients in the high exosomal PD-L1 group was significantly lower than that of patients in the low exosomal PD-L1 group (P = 0.0042); however, there was no significant correlation between soluble PD-L1 and OS in GC patients (P = 0.0501). Furthermore, we found that the expression of exosomal PD-L1 was positively correlated with the proportions of polymorphonuclear MDSCs (PMN-MDSCs, r = 0.4944, P < 0.001) and monocytic MDSCs (M-MDSCs, r = 0.3663, P = 0.005) in GC patients, indicating that exosomal PD-L1 might induce immune suppression by promoting the aggregation of MDSCs. In addition, we found that exosomal PD-L1 might stimulate MDSC proliferation by triggering the IL-6/STAT3 signaling pathway in vitro. The CDX model confirmed that exosomal PD-L1 could stimulate tumor development and MDSC amplification., Conclusions: Exosomal PD-L1 has the potential to become a prognostic and diagnostic biomarker for GC patients. Mechanistically, MDSCs can be activated by exosomal PD-L1 through IL-6/STAT3 signaling and provide a new strategy against GC through the use of exosomal PD-L1 as a treatment target., (© 2024. The Author(s).)

Background: Modified Jianpi Yangzheng decoction (mJPYZ), as an empirical decoction of Traditional Chinese medicine has been shown significantly to prolong the survival of patients with advanced stage gastric cancer. Pyruvate kinase M2 (PKM2), has attracted attention for its important role on cellular aerobic glycolysis, however, few studies focus on PKM2 non-metabolic roles in tumor progression., Purpose: Our study aimed to investigate the potential role of gastric cancer exosomes containing PKM2 in regulating tumor-associated macrophages (TAM) and the mechanism of mJPYZ against gastric cancer., Methods: Colony Formation Assay, flow cytometry and TUNEL staining were employed to estimate the effect of mJPYZ on gastric cancer in tumor-bearing mice and cells. Western blot analyzed apoptosis-related protein expression changes. Network pharmacology and bioinformatics predicted potential exosomes modulation of mJPYZ in gastric cancer. Exosomes were isolated and co-cultured with TAM. Diff-Quik Staining observed the TAM morphological changes when incubating with gastric cancer cells exosomes. Flow cytometry and immunofluorescence were performed to demonstrate whether exosomes PKM2 involved in TAM polarization., Results: mJPYZ induced apoptosis of gastric cancer cells by targeting PKM2 and downregulating PI3K/Akt/mTOR axis in vivo and in vitro. Network pharmacology showed potential exosomes modulation of mJPYZ in gastric cancer. We extracted exosomes and found mJPYZ decreased the abundance of serum exosomes PKM2 in patients with advanced gastric cancer and xenograft tumor model. Additionally, we firstly detected and confirmed that PKM2 is a package protein of exosomes extracted from gastric cancer cells, and mJPYZ could diminish the content of exosomal PKM2 in gastric cancer cells. Importantly, mJPYZ reduced the delivery of exosomal PKM2 from tumor cells to macrophages, and alleviated exosomal PKM2-induced differentiation of M2-TAM in tumor microenvironment, eventually inhibited gastric cancer progression., Conclusion: Gastric cancer exosomes containing PKM2 could lead to M2 macrophages differentiation, thereby promoting gastric cancer progression. Our findings provide a rationale for potential application of mJPYZ in the treatment of gastric cancer via PKM2., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Jianpi Yangzheng decoction (JPYZ) possesses a potential anti-tumor activity in gastric cancer. However, potential effect of JPYZ on regulating tumor-associated macrophage (TAM)-derived exosomes to affect gastric cancer is still unclear. We aimed to clarify the role of tumor-associated macrophage derived exosomes (TAM-exos) in invasive and metastasis of gastric cancer and the mechanism of JPYZ regulate TAM-exos against gastric cancer. Flow cytometry was performed to demonstrate whether JPYZ involved in TAM polarization. After JPYZ treatment, TAM conditioned medium (TAM-CM)/TAM-exos were co-cultured with gastric cancer cells and were detected by wound healing and transwell assay. Transcriptome sequencing and bioinformatics analysis predicted the exosomal miRNA after JPYZ intervention in TAM. miRNA mimic and inhibitor were used to verify the effect of miRNA in exosomes on gastric cancer cells. Q-PCR and luciferase reporter assay were employed to clarify the targeting relationship between miRNA and target gene. Western blot assay detected the expression levels of epithelial-mesenchymal transition (EMT) markers and related signaling pathways proteins. We firstly demonstrated that TAM-CM intervened by JPYZ significantly inhibited the invasion and migration of gastric cancer. Furthermore, exosomes in TAM supernatants play a key role in migration of gastric cancer. Meanwhile, transcriptome sequencing and q-PCR revealed that miR-513b-5p expression was significantly reduced in TAM-exos intervened by JPYZ. And miR-513b-5p in TAM aggravated TAM-exos mediated invasion and migration of gastric cancer cells, the inhibitor of miR-513b-5p reversed TAM-exos mediated promotion. Bioinformatics analysis and luciferase reporter assay confirmed that PTEN was a direct target of miR-513b-5p in gastric cancer. MiR-513b-5p inhibited PTEN to activate AKT/mTOR signaling pathway thus promoting gastric cancer invasion and metastasis in vivo and in vitro. Importantly, JPYZ inhibited TAM derived exosomal miR-513b-5p, and alleviated AKT/mTOR activation by PTEN depended manner in gastric cancer. TAM-exos containing miR-513b-5p lead to gastric cancer invasion and migration. Our findings clarify a novel TAM-exos mechanism of JPYZ for inhibiting gastric cancer progression. [Display omitted] • JPYZ could inhibit the invasion and migration of gastric cancer through TAM-exos. • JPYZ reduced the level of miR-513 b-5p in TAM-exos and affected the progression of gastric cancer. • JPYZ inhibited the progress of gastric cancer by regulating TAM-exos miR-513 b-5p mediated PTEN/AKT signaling. [ABSTRACT FROM AUTHOR]