Abstract
1039
Purpose: Recently enhanced Toll-like receptor (TLR) 5 expression was found in breast cancer,but whether it could be used as monitoring target in vivo for triple-negative breast cancer and underlying mechanisms is not fully understood. Methods: The TLR5 and CDK9 /NF-kB P65 expression was detected by Western Blot and qPCR in triple negative breast cancer cell lines 4T1 and EMT-6; 125I-anti-TLR5 was prepared and identified,then injected through tail veins to those established breast cancer-bearing mice models. Biodistribution and whole-body phosphor-autoradiography were performed. TLR5 expression of tumor was proved with immunohistochemical staining. The effect of CDK9 inhibitor, Flavopiridol , on TLR5 expression and anti-tumor was evaluated both in vitro and in vivo. Results:The expression of TLR5 both on protein and mRNA in 4T1 cells were significantly higher than EMT6(p<0.01). The proliferation was drastically inhibited when treated with Flavopiridol( 5 and 20μM) for 24 hours together with down-regulated expression of TLR5,CDK9 and NF-κB both in 4T1 and EMT6 cells ; 125I-anti-TLR5 was successfully prepared with 93.12% labeling rate and keep stable until 96h. 125I-anti-TLR5 could specific bind to 4T1 and EMT6 cells in vitro with high affinity ,specificity but different Bmax. Ex vivo biodistribution studies showed that 125I-anti-TLR5 were mainly metabolized through the liver and kidney, focused in tumors, especially in 4T1.4T1 Tumors could be observed early in 24h ,obviously shown in 48h after 125I-anti-TLR5 injection,much clearer than isotype IgG group and lower TLR5 expression EMT6 tumor which positively related with tumor TLR5 expression. Further, in vivo assessment of the therapeutic effects of Flavopiridol resulted in a significant reduction of tumor Conclusion:Our data suggested that TLR5 expressed on triple-negative breast cancer could be a molecular target for monitoring tumor growth in vivo and Flavopiridol may carry out its anti-tumor effect through CDK9-TLR5-NF-κB pathway.