ABSTRACT
ObjectiveTo study the effect of Bushen Huoxuetang on the apoptosis and the expression of B-cell lymphoma （Bcl-2）-associated X protein （Bax）/ Bcl-2 and cleaved cysteine-containing aspartate proteolytic enzyme-3 （cleaved Caspase-3） in the nude mouse model of bone metastasis of breast cancer， and explore the mechanism of Bushen Huoxuetang in inhibiting bone destruction. MethodThirty BALB/c female nude mice were randomly assigned into blank group （n=6） and model group （n=24）. The suspension of 4T1 breast cancer cells was injected into the tibia of mouse right lower limb to establish model of bone metastasis of breast cancer. The successfully modeled nude mice were randomly assigned into model group， Bushen Huoxuetang group， zoledronic acid group， and combined drug group， with 6 mice in each group. Bushen Huoxuetang was administrated at a dose of 36.67 g·kg-1， once a day， and zoledronic acid was administrated by subcutaneous injection at a dose of 100 μg·kg-1， twice a week. The combined drug group was administrated with the same doses of Bushen Huoxuetang group by gavage and zoledronic acid by subcutaneous injection. The mice in the blank group and the model group were administrated with the same volume of distilled water by gavage for 14 days. On the next day at the end of drug administration， the mice were sacrificed by cervical dislocation. The general situation and weight changes of the mice were examined. The right lower limb was collected， and X-ray scanning and hematoxylin-eosin （HE） staining methods were used for observation of pathological changes in the bone. The terminal deoxynucleotidyl transferase dUTP nick-end labeling （TUNEL） was employed to detect the apoptosis of bone tissue in nude mice， and Western blot to determine the expression of Bax/Bcl-2 and cleaved Caspase-3 in the bone tissue. ResultCompared with the blank group， the modeling reduced the body weight （P<0.01） and increased the right lower limb weight of the nude mice （P<0.01）. Compared with the model group， Bushen Huoxuetang， zoledronic acid， and their combination increased the body weight （P<0.01） and decreased the right lower limb weight （P<0.01）. Compared with the blank group， the other groups showed obvious tumor cell atypia， deep nuclear staining， and clear bone metastasis， and the model group showed obvious osteolytic damage in right lower limb and loss of proximal tibia and knee joint. Compared with the model group， Bushen Huoxuetang， zoledronic acid， and their combination reduced the osteolytic lesions in the right lower limb and recovered part of the bone structure， demonstrating an inhibitory effect on bone destruction. The TUNEL assay showed that the model group had lower apoptosis rate of bone metastatic tumor cells than the blank group， Bushen Huoxuetang group， zoledronic acid group， and combined drug group （P<0.01）. Compared with the blank group， the modeling down-regulated the expression of Bax and cleaved Caspase-3 （P<0.01） and up-regulated the expression of Bcl-2 （P<0.01）. Compared with the model group， Bushen Huoxuetang， zoledronic acid， and their combination up-regulated the expression of Bax （P<0.01） and cleaved Caspase-3 （P<0.05， P<0.01） and down-regulated the expression of Bcl-2 （P<0.05， P<0.01）. ConclusionBushen Huoxuetang may inhibit bone destruction in the nude mouse model of bone metastasis of breast cancer by up-regulating the expression of Bax， down-regulating the expression of Bcl-2， activating cleaved Caspase-3， and further inducing apoptosis.