Toll-Like Receptor-4 Signaling Pathway Influenced the Exosome Biogenesis and Angiogenesis in Human Triple-Negative Breast Cancer Cells.

Purpose: The close relationship of the toll-like receptor (TLR) signaling pathway has been indicated with different bioactivates of tumor cells. Here, the impact of TLR4 signaling pathway stimulation/inhibition was assessed on angiogenesis and exosome (Exo) biogenesis in MDA-MB-231 cells. Methods: Cells were incubated with lipopolysaccharide (LPS) and simvastatin (SIM) for 48 hours. Cell survival and TLR4 signaling pathway genes were measured using MTT and real-time PCR analysis. The physicochemical properties of Exos were studied using DLS, SEM, and western blotting. The migration capacity and angiogenesis-related genes were assessed using the Transwell insert assay and real-time PCR analysis. Results: Data indicated that SIM and LPS can reduce the survival rate in a dose-dependent manner compared to the control cells (P<0.05). The expression of TLR4, NF-κB, IL-1β, MYD88, and TRIF was increased in LPS-treated cells compared to the control group (P<0.05), while these genes were down-regulated or remained unchanged in the SIM group. SEM analysis indicated the reduction of Exo diameter in the LPS groups (P<0.05) with a slight increase of CD63, TSG101, and Rab27 in the presence of LPS. We found an enhanced and reduced migration rate in the LPS and SIM groups compared to the non-treated control cells (P<0.05). The expression of genes related to angiogenesis was down-regulated in both SIM and LPS groups. Conclusion: These data indicate that the TLR4 signaling pathway can control the angiogenesis and Exo production in breast cancer cells, which paves the way for the development of de novo therapies in breast cancer patients.