Baicalin Promotes Apoptosis of Human Medullary Breast Cancer via the ERK/p38 MAPK Pathway

Objectives: The present study aims to examine the effects of baicalin on the human medullary breast carcinoma (MBC) cell line Bcap-37 and to determine whether baicalin regulates Bcap-37 cell apoptosis through the ERK/p38 mitogen-activated protein kinase (MAPK) signaling pathway. Materials and Methods: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Transwell assay were utilized to measure the effects of baicalin on the proliferation and migration ability of Bcap-37 cells, respectively. Flow cytometer analysis was implied to detect the effects of baicalin on Bcap-37 cell apoptosis. Real-time quantitative polymerase chain reaction (RT-PCR) was conducted to observe the influence of baicalin on mRNA expressions of apoptosis-related genes. Western blot was executed to further explore the action of baicalin on apoptosis-related proteins. PD98059 (a specific inhibitor of ERK) and SB203580 (a specific inhibitor of p38 MAPK) were used to further clarify the intrinsic mechanism of baicalin regulating apoptosis in Bcap-37 cells. Results: Compared with the control group, baicalin significantly inhibits the proliferation activity of Bcap-37 cells in a concentration- and time-dependent manner, with a p-value < 0.05. The transwell assay indicated that the migration viability of cells decreased further, followed by the increased concentration of baicalin, and the p-value had a statistical difference. Besides, flow cytometry was conducted to assess the effects of baicalin on the early and late apoptosis rates of Bcap-37 cells, and results showed that baicalin highly promoted the apoptosis level both at the early and late stages with a statistical difference in a concentration-dependent manner ( p < 0.05). Results of RT-PCR presented that, compared with the control group, baicalin significantly activated the mRNA expression of Bax, p38, and p-ERK1 and abolished the mRNA expression of Bcl-2 in every dosing group in a concentration-dependent way ( p < 0.05). Western blot exhibited that, compared with the control group, baicalin promoted the protein expression of caspase-3, caspase-9, Bax, p38, P-ERK, and p53 while playing an opposite function to Bcl-2 in each dosing group ( p values have statistical differences). At last, PD98059 and SB203580 were applied to explore the potential mechanism of baicalin in apoptosis promotion. And results revealed that, compared with the group treated with baicalin alone, protein expression of Bax, p38, p-ERK, caspase-3, and caspase-9 was downregulated obviously in the group treated with both baicalin and PD98059 or SB203580 ( p < 0.05). The p53 expression inhibition showed a difference only when compared to the group adding PD98059. Compared with the blank group, a statistical difference was only observed in Bcl-2 expression in the group treated with baicalin in combination with PD98059 or SB203580 ( p < 0.05). Interestingly, a p53 expression difference was only displayed between the blank group and the group treated with baicalin and SB203580 ( p < 0.05). Conclusion: Our study observed that baicalin inhibits the proliferation and migration ability of Bcap-37 cells. In addition, baicalin induces cell apoptosis via the ERK/p38 MAPK signal pathway.