Silymarin inhibits Toll-like receptor 8 gene expression and apoptosis in Ramos cancer cell line.

Abstract

Silymarin is a herbal extract containing flavonolignans, and it has inhibitory effects against the growth of different cancer cell lines by inducing apoptosis. Toll-like receptors are suggested as a novel and attractive target to treat cancer. The current study aimed at examining the mechanism of silymarin-induced apoptosis in Ramos cells and investigating its effects on TLR8 expression. The half maximal inhibitory concentration (IC50) of silymarin in Ramos cells was determined via MTT viability test while the type of cell death was tested by annexin V/propidium iodide (PI) double staining method. The activity of caspase-3 and expression of TLR8 were measured in a time-dependent manner (in IC50) by colorimetric assay and real-time polymerase chain reaction (RT-PCR), respectively. The results of MTT showed that IC50 of silymarin in Ramos cells was 100 μg/ml after 48 hr treatment (p<0.01). Flow cytometry by annexin V/PI, showed that silymarin induced early/late apoptosis in this cell line (p<0.05 to p<0.01). In addition, the caspase-3 colorimetric method showed that caspase-3 increased in the Ramos cell line after treatment (p<0.01). This treatment led to a reduction in TLR8 mRNA expression in a time-dependent manner (p<0.01). The results indicated a new mechanism in the anticancer activity of Toll-like receptor (TLR) signaling after silymarin treatment in Ramos cancer cell line. This plant could be used to develop anticancer agents inhibiting TLRs.