Objective To evaluate the effect of apigenin on breast cancer growth and lung metastasis in MMTV-PyMT.

Methods MMTV-PyMT female mice aged 9-week were selected and divided into the apigenin treatment and control groups. In the apigenin treatment group (n = 5), mice were treated with intraperitoneal injection of 5 mg/kg apigenin, while those in the control group (n = 5) were given with intraperitoneal injection of DMSO at the equivalent dose for 4 weeks. Body weight and tumor volume of the mice were measured during the treatment. After 4 weeks, the tumors and lung tissues of the mice were isolated. Tumor weight was measured, and the number of nodules on the lung surface was counted. Immunohistochemical staining was used to detect the number of proliferating cells and microvessels in the tumor tissues.

Results Compared with the control group, the tumor volume of the apigenin-treated mice was significantly smaller and tumor weight was significantly lighter than than those in the control group. Moreover, the number of metastatic nodules on the lung surface in the apigenin treatment group was significantly lower than that in the control group (all P ＜ 0.05). The results of immunohistochemistry showed that the number of proliferating cells (Ki67) and microvessel density in the apigenin treatment group were significantly lower than those in the control group (both P ＜ 0.05).

Conclusion Apigenin significantly inhibits the growth and lung metastasis of breast cancer in MMTV-PyMT mice probably by inhibiting tumor cell proliferation and angiogenesis.