Tim-3 promotes cell aggressiveness and paclitaxel resistance through NF-κB/STAT3 signalling pathway in breast cancer cells

Objective:Although T-cell immunoglobulin and mucin-domain containing molecule-3(Tim-3)has been recognized as a promising target for cancer immunotherapy,its exact role in breast cancer has not been fully elucidated.Methods:Tim-3 gene expression in breast cancer and its prognostic significance were analyzed.Associated mechanisms were then explored in vitro by establishing Tim-3-overexpressing breast cancer cells.Results:In a pooled analysis of The Cancer Genome Atlas(TCGA)database,Tim-3 gene expression levels were significantly higher(P<0.001)in breast cancer tissue,compared with normal tissues.Tim-3 was a prognosis indicator in breast cancer patients[relapse-free survival(RFS),P=0.004;overall survival(OS),P=0.099].Tim-3 overexpression in Tim-3 low breast cancer cells promoted aggressiveness of breast cancer cells,as evidenced by enhanced proliferation,migration,invasion,tight junction deterioration and tumor-associated tubal formation.Tim-3 also enhanced cellular resistance to paclitaxel.Furthermore,Tim-3 exerted its function by activating the NF-κB/STAT3 signalling pathway and by regulating gene expression[cyclin D1(CCND1),C-Myc,matrix metalloproteinase-1(MMP1),TWIST,vascular endothelial growth factor(VEGF)upregulation,concomitant with Ecadherin downregulation).Lastly,Tim-3 downregulated tight junction-associated molecules zona occludens(ZO)-2,ZO-1 and occludin,which may further facilitate tumor progression.Conclusions:Tim-3 plays an oncogenic role in breast cancer and may represent a potential target for antitumor therapy.