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TLR4 signaling in miR-21 expression and proliferation/apoptosis in breast carcinoma 4T1 cells
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Abstract:
Objective:To investigate the effect of TLR4 signaling on breast cancer cell proliferation/apoptosis and the underlying mechanism in vitro.Methods: Breast carcinoma 4TI cells were stimulated with 100 ng/ml lipopolysaccharide (LPS) after a preincubation with DMSO or NF-κB inhibitor PDTC for 30 min. At 6, 12, 18 and 24 h after LPS stimulation, levels of miR-21 were measured by qRT-PCR, phospho-NF-κBp65 was determined by Western blotting analysis. Apoptosis and cell viability in 4T1 cells transfected with mock (control) or an miR-21/inhibitor were assessed by Annexin-V/PI staining and MTT assay,respectively. Results: LPS induced significant increasement of miR-21 level and NF-κB activation in 4T1 cells in a time-dependent manner (18 h: 207±0.33 vs 1; t=5.61, P=0.03), which were significantly attenuated by NF-κB inhibitor PDTC. Transfection of 4T1 cells with miR21 inhibitor resulted in a significant increase in apoptosis (0.70±0.10 vs 2.14±0.32; t=-7.357,P=0.002) and a significant decrease in cell growth (042±0.02 vs 0.55±0.01；t=-8.528, P=0.001), as compared with transfection with mock. Conclusion: Activation of TLR4 signaling pathways may up-regulate miR-21 through NF-κB activation in breast carcinoma 4T1 cells. Targeted inhibition of miR-21with a sequence-specific inhibitor can effectively induce apoptosis and suppress 4T1 cell growth, thus having a great potential in the treatment of breast carcinoma.
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Project Supported:
Project supported by the National Natural Science Foundation of China (No. 81172515)
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