Extract of Caulis Spatholobi, a novel platelet inhibitor,efficiently suppresses metastasis of colorectal cancer by targeting tumor cell-induced platelet aggregation

Tumor cell-induced platelet aggregation (TCIPA) is the core mechanism potentiating high viability for circulatory tumor cells,which is the rate-limiting factor for metastasis. Additionally,as supported by the successful application of aspirin,the pro-malignant effects during tumor-platelets interaction can be largely neutralized by pharmacological deactivation of platelets. Caulis Spatholobi is widely used as an anti-coagulation herb in traditional Chinese medicine,indicating its potential against TCIPA. In our study,three fractions of Caulis Spatholobi extracts were firstly prepared. In colorectal cancer(CRC) model,the anti-metastatic potential was evaluated both in vitro and in vivo followed by the detection of their platlet regulatory effects. Results showed that all three extracts significantly suppressed the invasion and metastasis of CRC. Mechanistically,by blocking platelet-derived PDGF-B releasing,they reversed the enhanced epithelial mesenchymal transition during MC38-platelets interation. Further,ethyl acetate fraction shows the most promising efficacy for the future application in treatment. Overall,our study have for the first time proved CaulisSpatholobi extracts,especially the ethyl acetate fraction,as a potent TCIPA inhibitor during metastatic progression,which provided a novel candidate for pharmacologically blockage of metastasis in CRC.