Mobile website
Basic Research
Bufalin reduces PD-L1 expression in colorectal cancer cells through suppressing TAM-mediated STAT3 phosphorylation
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
[Abstract] Objective: To investigate the regulatory effect of bufalin (BU) on tumor-associated macrophage (TAM)-mediated programmed death-ligand 1 (PD-L1) expression in colorectal cancer (CRC) cells and to elucidate the underlying molecular mechanism. Methods: An in vitro co-culture system was established using HCT116 cells and THP-1-derived macrophages. THP-1 cells were differentiated into M0 macrophages by PMA treatment and further stimulated with HCT116-conditioned medium (CM) to generate TAM-like cells. Flow cytometry was used to detect CD11b and CD206 expressions and assess macrophage polarization level. The changes in the expression levels of TGF-β, IL-10, STAT3/p-STAT3, and PD-L1 were detected by RT-qPCR and WB assay. A STAT3 knockdown cell line (HCT116-shSTAT3), constructed by lentiviral transduction, was combined with BU treatment to verify the role of the STAT3/PD-L1 signaling pathway. Results: HCT116-derived CM induced macrophage polarization toward the M2 phenotype, as evidenced by an increased proportion of CD11b+CD206+ cells (P < 0.01) and elevated expression of TGF-β and IL-10 (both P < 0.001). TAM-conditioned medium significantly promoted STAT3 phosphorylation (P < 0.001) and upregulated PD-L1 expression at both mRNA and protein levels in HCT116 cells (P < 0.001 or P < 0.01). BU treatment markedly suppressed TAM-mediated STAT3 phosphorylation and concomitantly reduced PD-L1 expression (both P < 0.01). STAT3 knockdown decreased PD-L1 expression, with a trend consistent with BU treatment. Conclusion: BU can downregulate PD-L1 expression in CRC cells by inhibiting TAM-mediated STAT3 signaling activation, suggesting its potential application value in the tumor immune microenvironment.
Keywords:
Project Supported:
Clc Number:
