Tribulus terrestris L. induces cell apoptosis of breast cancer by regulating sphingolipid metabolism signaling pathways.

BACKGROUND: Tribulus terrestris L. (TT) was initially documented in Shen-Nong-Ben-Cao-Jing and has been used for thousands of years in China as a herb to calm liver, dispel melancholy and wind, promote blood circulation, improve eyesight, and relieve itching. Moreover, it was also used to treat breast cancer in ancient China. However, the pharmacological activities of TT extract on breast cancer have received little attention.

PURPOSE: In this study, we investigated the anti-breast cancer effects and possible mechanisms of action of this herbal drug.

METHODS: Network pharmacology analysis the study of network pharmacology was done to analyze the possibility of TT's anti-breast cancer effect. And then, molecular docking between TT7/TT8 and vascular endothelial growth factor receptor 2 (VEGFR2) were performed by Autodock software as well as the related protein expressions were analyzed by western blot to verify this effect. In vivo experiment: The mouse model of breast cancer was established by injection of 4T1 cells. Then drugs were intragastrically administered to the mice once daily for fourteen days. Body weight, tumor size, and tumor weight were recorded at the end of the experiment. Moreover, tumor inhibitory rate was calculated. Finally, pathological changes and apoptosis of breast cancer tissues were respectively evaluated by HE and Hoechst staining. Proteomics and metabonomics analyses: The tumor tissues were chosen to perform conjoint analysis. Firstly, differential proteins and metabolites were found. Furthermore, the functional analyses of them were analyzed by software. At the last, immunofluorescent staining of SGPP1, SPHK1 and p-SPHK1 in tumor tissue were done.

RESULTS: 12 active ingredients of TT, 127 targets of active ingredients, 15,253 targets of breast cancer, 1,225 targets of Ru yan, and 123 overlapping genes were obtained in the network pharmacology study. There was firm conjunction between TT7/TT8 and VEGFR2. Besides, tumor size and weight were markedly reduced in TT groups compared to the model group. The tumor inhibitory rate was more than 26% in TTM group. After drug treatment, many adipocytes and cracks between tumor and apoptosis were discovered. The western blot results showed that TT aqueous extract lowered the levels of VEGFR2, ERK1/2, p-ERK1/2 (Thr202, Tyr204) and Bcl2, while increasing the levels of Bax and the ratio of Bax/Bcl2. Furthermore, 495 differential proteins and 76 differential metabolites were found between TTM and model groups with the sphingolipid metabolism pathway being enriched. At last, TT treatment significantly reduced the levels of SGPP1, SPHK1 and p-SPHK1 in tumor tissue.

CONCLUSIONS: In conclusion, TT demonstrates therapeutic effects in a mouse model of breast cancer, and its mechanism of action involves the regulations of sphingolipid metabolism signaling pathways. This study lends credence to the pharmacological potential of TT extract as a breast cancer therapy.