TLR5: A prognostic and monitoring indicator for triple-negative breast cancer

Abstract

A novel, highly selective biomarker is urgently needed to predict and monitor triple-negative breast cancer (TNBC) because targeting molecules are not currently available. Although associated with various malignant tumors, the role of toll-like receptor 5 (TLR5) in TNBC remains uncertain. We aimed to define the effects of TLR5 in TNBC to determine whether it could serve as a prognostic and monitoring indicator for TNBC. We established TNBC cell line 4T1 with low TLR5 expression (GFP tag; TLR5− 4T1) and with normal TLR5 expression (GFP tag; TLR5+ 4T1) using lentivirus-shRNA-TLR5 knockdown transfection and negative lentivirus transfection, respectively. Detected by western blot and qPCR, we found knockdown of TLR5 resulted in decreased expression of TLR5 and E-cadherin and increased expression of N-cadherin, vimentin, fibronectin, TRAF6, SOX2, and Twist1, which were related to EMT (epithelial–mesenchymal transition). In addition, downregulation of TLR5 increased the invasion and migration of 4T1 cells in vitro, which were investigated by CCK-8 and wound healing, as well as transwell assay and colony formation. Furthermore, the metastatic ability of TLR5− 4T1 cells to the lungs was also increased compared to TLR5+ 4T1 cells in vivo. To verify the effect of TLR5 as a monitor indicator, mice bearing TLR5+ and TLR5− 4T1 tumors injected with 125I-anti-TLR5 mAb or isotype 125I-IgG were assessed by whole body phosphor-autoradiography and fluorescence imaging in vivo. Phosphor-autoradiography of model mice revealed early tumors at 6 days after inoculation with TLR5+ 4T1, but not TLR5− 4T1 cells. Intratumoral accumulation of radioactivity positively correlated with TLR5 expression, and fluorescence imaging in vivo revealed both TLR5+ and TLR5− 4T1 tumors. Our results suggested that downregulation of TLR5 in TNBC increased tumor invasiveness and EMT expression via TRAF6 and SOX2 pathway and TLR5 could serve as a prognostic and monitoring indicator for TLR5-positive tumors.

The relationship between TRAF6 and tumors

“…Many studies suggest that the acquisition of mesenchymal characteristics in tumor cells enhances tumor invasion. EMT has critical roles in metastasis and invasion of many types of cancers, including breast cancer, prostate cancer and head and neck squamous cell carcinoma (HNSCC) [ 61 – 63 ]. The study showed that EMT procedure was significantly blocked after inhibition of TRAF6 expression in HNSCC cell lines [ 63 ] (Fig.…”

Down-Regulation of Toll-Like Receptor 5 (TLR5) Increased VEGFR Expression in Triple Negative Breast Cancer (TNBC) Based on Radionuclide Imaging

“…It has been reported that TLR5 was closely related to the proliferation, invasion, and metastasis of TNBC. Downregulation of TLR5 enhanced proliferation, invasion, and metastasis of TNBC (19,21). The TNBC-bearing mice model showed similar biological behavior to human diseases (22).…”

Patient-Specific Network for Personalized Breast Cancer Therapy with Multi-Omics Data

“…TRAF6 is also involved in the activation of mTROC1 and PI13K [ 52 ]. While little is known regarding the association of TRAF6 in breast cancer, it was found over-expressed in triple negative BC and it expression correlates with metastatic outcome [ 53 ]. In addition, a recent study reported that a molecule, an inhibitor of TRAF6, decreases metastasis in mouse BC models [ 54 ].…”