Tiliroside suppresses triple-negative breast cancer as a multifunctional CAXII inhibitor

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by poor prognosis, early recurrence, and the lack of durable chemotherapy responses and specific targeted treatments. In this preclinical study, we examines Tiliroside (TS, C(30)H(26)O(13)), as one of the major compounds of Tribulus terrestris L. which has been used as an alternative therapy in clinic practice of breast cancer treatment, for its therapeutic use in TNBC. The association between CAXII expression level and survival probability of TNBC patients, and the difference of CAXII expression level between TNBC and normal samples were evaluated by using publicly accessible databases. To determine the anticancer efficacy of TS on TNBC cells, cell proliferation, wound healing, cell invasion, and 3D spheroid formation assays were performed and excellent anticancer activities of TS were displayed. Mouse models further demonstrated that TS significantly reduced the tumor burden and improved survival rate. The properties of TS as a novel CAXII inhibitor have also been evaluated by CAXII activity assay, pHi, pHe and lactate level assay. Further RT-PCR and Caspase-3 activity analyses also revealed the positive regulating effects of TS on E2F1,3/Caspase-3 axis in TNBC cells cultured in 2D or 3D systems. The findings indicate that TS suppresses TNBC progression as a potential novel CAXII inhibitor in preclinical experiments, which warrants further investigation on its therapeutic implications.