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Polysaccharide-containing fraction from Artemisia argyi inhibits tumor cell-induced platelet aggregation by blocking interaction of podoplanin with C-type lectin-like receptor 2

Tseng, Ching-Ping, Huang, Yu-Ling, Chang, Yao-Wen, Liao, Hsiang-Ruei, Chen, Yu-Li, Hsieh, Pei-Wen
Yàowù shípǐn fēnxī 2020 v.28 no.1 pp. 115-123
Artemisia argyi, Oriental traditional medicine, Western blotting, antagonists, blood platelets, dose response, enzyme inhibition, fractionation, leaves, metastasis, neoplasm cells, neoplasms, patients, platelet aggregation, screening
Tumor cell-induced platelet aggregation (TCIPA) is a mechanism that involves the protection of tumor cells in the circulation and the promotion of tumor cell invasion and metastases. The C-type lectin-like receptor 2 (CLEC-2) that binds podoplanin (PDPN) is on the platelet surface and facilitates the TCIPA. Selective blockage of the PDPN-mediated platelet-tumor cell interaction is thereby a plausible strategy for inhibiting metastases. In a search for antagonists of PDPN- and tumor cell-induced platelet aggregation, traditional Chinese medicines were screened and it was found that the water extract of Artemisia argyi leaves selectively inhibited the PDPN-induced platelet aggregation. Bioactivity-guided fractionation analysis was performed for defining a polysaccharide-containing fraction (AAWAP) characterized by inhibition of PDPN activity and tumor cell-induced platelet aggregation. The pharmacological effects of AAWAP on PDPN-activated CLEC-2 signaling were determined by using Western blot and alpha screening analyses. AAWAP was non-toxic to the cells and platelets and it suppressed PDPN- and tumor cell-induced platelet aggregation by irreversibly blocking the interaction between PDPN and CLEC-2 in a dose-dependent manner. These findings indicate that AAWAP is an antagonist of the PDPN-CLEC-2 interaction. This action by AAWAP may result in the prevention of tumor cell metastases, and if so, could become an effective pharmacological agent in treating cancer patients.