Effect of Weimaining on Apoptosis and Caspase-3 Expression in a Breast Cancer Mouse Model

Ethnopharmacological relevance: Weimaining (WMN) is a condensed Tannin compound extracted from Fagopyrum cymosum (Trevir.) Meisn., which comes from the roots of buckwheat, a type of Chinese herbal medicine, was first recorded in "Bencao Shiyi". WMN has inhibitory effects on multiple cancer types and is widely used in clinical practice; however, the mechanism underlying the anti-tumor effect of WMN is still unclear.

Aim of the study: To investigate the effect of WMN on the cellular activity and apoptosis of mouse breast cancer 4T1-luc2 cells, and caspase-3 and cleaved-caspase-3 expression.

Materials and methods: Luciferase-labeled mouse breast cancer 4T1-luc2 cells were inoculated into the mouse breast pad to establish a luciferase-labeled mouse breast cancer cell model. BALB/C-nu mice were randomly divided into model, WMN, and low-molecular-weight heparin (LMWH) groups (n=10). Another 10 mice served as the normal control group (no cancer cell injection). The WMN group was administered WMN 250 mg/kg per day for 14 days, the LMWH group was given LMWH (1500 U/kg) daily for 14 days by intraperitoneal injection, and the model and normal control groups were given an equal dose of 0.9% NaCl. The number and distribution of transplanted tumors in 4T1-luc2 breast cancer cells were observed in nude mice by an in vivo imaging system at the time of inoculation after successful modeling, and on days 7 and 14 after drug administration. Tumor cell apoptosis was detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method; caspase-3 mRNA expression was detected by RT-PCR and Western blotting was applied to detect the levels of caspase-3 and cleaved-caspase-3 protein expression.

Results: The apoptosis index (AI) of the WMN group was detected by the TUNEL method, and the AI increased with the increase of treatment time. Compared with the model group, the mRNA expression of caspase-3 and the protein levels of caspase-3 and cleaved-caspase-3 were notably elevated in the WMN group. After in vivo bioluminescent imaging, the total photon number of the WMN group was found to be lower than that of the LWMH group on day 14 after administration. Additionally, the AI and expression levels of caspase-3 mRNA, caspase-3, and cleaved-caspase-3 protein of the WMN group were higher than those of the LWMH group.

Conclusion: WMN can effectively suppress the growth of 4T1-luc2 breast cancer xenografts in mice, and promote the apoptosis of breast cancer cells by upregulating the expression of caspase-3.

Keywords: Weimaining; apoptosis; breast cancer; caspase-3; in vivo imaging technology.