Mechanism of Rabdosia rubescens extract against gastric cancer microenvironment by SIRT1/NF-κB/p53 pathway and promoting tumor-associated macrophage polarization

Abstract

Ethnopharmacological relevance: The traditional action of Rabdosia rubescens (Hemsl.) H. Hara is heat-clearing and detoxifying, relieve sore throat, dissipate binds and disperse swelling. DLC, as an extract prepared from Rabdosiae Rubescentis Herba, could regulate the polarization of tumor associated macrophages (TAMs). For TAMs play an important role in the tumor microenvironment. It is worthy to further explore the mechanism of DLC on the polarized function of macrophages.

Aim of the study: The aim of this study is to investigate the activity and molecular mechanisms of DLC on dissipating binds and dispersing swelling by modulating the gastric cancer microenvironment and macrophage polarization.

Materials and methods: We conducted comprehensive qualitative and quantitative chromatographic analyses to characterize the main components of DLC. To evaluate its anti-tumor effects, immunofluorescence, MTT assay, plate cloning, transcriptomics analysis, western blotting, and siRNA knockdown experiments were performed to assess DLC's action on gastric cancer cell proliferation. Additionally, we utilized Trypan blue staining, a THP-1 and MGC-803 co-culture model, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and a mouse xenograft model with five distinct dosage groups to systematically investigate DLC's effects on macrophage polarization.

Results: Key compounds in DLC were identified. The vivo tests demonstrated the tumor inhibition rate of the 5 g/kg DLC group reached 66.99 %, surpassing that of the 5-fluorouracil group (59.94 %). Mechanistically, DLC upregulated SIRT1 expression and suppressed NF-κB pathway, thereby preventing p65 from translocating into nuclear and modulating downstream p53/MDM2/USP7 signaling. Moreover, DLC enhanced M1 macrophage factors such as TNF-α, IL-6 while inhibiting M2 marker TGF-β, effectively repolarizing M2 TAMs toward an M1 phenotype. This effect was associated with suppressed protein expression of HIF-1α, p-p65, and p-PI3K.

Conclusion: This study provides insights into DLC's mechanisms in regulating tumor microenvironment remodeling and promoting macrophage polarization toward an anti-tumor phenotype. These results provide a solid basis for DLC's potential clinical treament in gastric cancer, highlighting its promise as a natural therapeutic agent.

Keywords: Polarization; Rabdosia rubescens extract; SIRT1/NF-κB; Tumor microenvironment; Tumor-associated macrophage.