To observe the effect of Pingxiao capsules on experimental breast cancer.

The 36 female SD rats were randomly divided into 6 groups: normal group, model group, tamoxifen group (0.36 mg/kg), low-dose Pingxiao capsule group (250 mg/kg), medium-dose group (500 mg/kg) and high-dose group (750 mg/kg). The rat model of breast cancer was established by intraperitoneal injection of 7, 12-dimethylbenz[a]anthracene (DMBA, 80 mg/kg). After 3 days, the rats had normal diet in normal group, while the rats were given drug intervention in other groups. After 25 weeks, the rats were observed for breast tumor and histopathological analysis was performed. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of estradiol (E₂), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), malondialdehyde (MDA) and tumor necrosis factor α (TNF-α) in serum of rats. The changes of viscera mass index in rats were observed. The analysis of variance (ANOVA) was used for comparison among multiple groups, and the LSD method was used for pairwise comparison. Repeated measurement data were analyzed by repeated measures of ANOVA.

(1) The repeated measures of ANOVA showed that time, grouping and interaction between time and grouping all affected body weight of rats (F=70.385, P < 0.001; F=19.389, P < 0.001; F = 3.184, P = 0.020). (2) The rats in model group had bilateral breast tumors, while the rats only had unilateral breast tumor after intervention of tamoxifen and Pingxiao capsules. The tumor volume in model group was (21.5±9.6) cm³. The breast tumor volume was (13.6±9.6), (20.1±5.3), (15.5±6.2), (5.2±2.3) cm³ in tamoxifen group, low-dose Pingxiao capsule group, medium-dose group and high-dose group, respectively. The breast tumor volume presented a significant difference between high-dose group and model group (P < 0.050). (3) The diameter of bilateral second nipples presented a significant difference among groups (right: F=11.378, P<0.001; left: F=9.600, P<0.001). Pairwise comparison showed that there were significant differences between model group and tamoxifen group/medium-dose Pingxiao capsule group/high-dose group (all P<0.050). There was a significant difference in nipple diameter between tamoxifen group and low-dose Pingxiao capsule group (P<0.050). (4) There were significant differences in serum levels of E₂, GSH-Px, SOD, MDA and TNF-α among groups (F=64.845, 60.303, 32.583, 80.558, 46.740, all P< 0.050). Compared with the normal group, the levels of E₂, MDA and TNF-α in model group were significantly increased (all P< 0.050), while the levels of GSH-Px and SOD were significantly decreased (all P< 0.050). There were significant differences in the levels of E₂, GSH-Px, SOD, MDA and TNF-α between model group and tamoxifen group/medium-dose Pingxiao capsule group/high-dose group (all P < 0.050); the levels of E₂, GSH-Px, SOD and MDA all presented significant differences between tamoxifen group and medium-dose/high-dose Pingxiao capsule group (all P< 0.050). (5) The viscera mass index of the uterus, thymus, spleen, liver and kidneys presented a significant difference among groups (F=3.502, 1.696, 13.672, 2.995, 4.465, all P<0.050). Compared with model group, the viscera mass index of the uterus, thymus and spleen in normal group, tamoxifen group, medium-dose Pingxiao capsule group and high-dose group all presented a significant difference (all P< 0.050); there was a significant difference between tamoxifen group and low-dose/medium-dose/high-dose Pingxiao capsule group (all P>0.050). The results of HE staining showed that in medium-dose Pingxiao capsule group and high-dose group, the rats had significantly improved mammary tumor-like changes, hyperplasia and expansion of ducts, less acini and relieved lesions.

Pingxiao capsules are effective in prevention and treatment of DMBA-induced breast cancer in rats, which be due to its regulation on serum E₂, GSH-Px, SOD, MDA and TNF-α levels, as well as oxidative stress state of the body, thus improving the immune regulation.