OBJECTIVE

2

To explore the improvement effect and potential mechanism of modified Yanghe decoction on bone destruction in rats with breast cancer bone metastasis based on the receptor-interacting serine/threonine-protein kinase 1 （RIPK1）/RIPK3 pathway.

METHODS

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The rat model of breast cancer bone metastasis was established by injecting a suspension of breast cancer cells into the bone marrow cavity. The rats with successful modeling were randomly divided into a model group （intragastric administration of equal volume of normal saline）， modified Yanghe decoction low-， medium-， and high-dose groups （intragastric administration of corresponding decoction at 1.30， 2.60 and 5.20 g/kg， calculated by the dosage of crude drug）， high-dose modified Yanghe decoction+si-RIPK1 group （intragastric administration of corresponding decoction at 5.20 g/kg， calculated by the dosage of crude drug； simultaneous injection of small interfering RNA for RIPK1 via the tail vein）， and high-dose modified Yanghe decoction+si-NC group （intragastric administration of corresponding decoction at 5.20 g/kg， calculated by the dosage of crude drug； simultaneous injection of small interfering RNA for negative control via the tail vein）， with 12 rats in each group. Another 12 healthy rats were selected as the control group and were given the same volume of normal saline intragastrically， once a day， for 14 consecutive days. Body weight was measured before administration and at the end of the last administration. The mechanical pain threshold and thermal pain threshold were measured， and the bone destruction， pathological changes and osteoclast formation of the tibia were observed. The positive expression of receptor activator of nuclear factor-κB （RANK） and receptor activator of nuclear factor-κB ligand （RANKL） in the tibial tissue， as well as the phosphorylation levels of RIPK1， RIPK3 and mixed lineage kinase domain-like protein （MLKL） were detected.

RESULTS

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Compared with the control group， the tumor cells of tibia tissues in rats of the model group showed significant proliferation and diffuse infiltration into the bone marrow cavity. Extensive areas of tumor necrosis of cells， severe bone destruction， thinning of the bone cortex， and damage to the bone trabeculae were observed. The body weight （before administration and at the end of the last administration）， mechanical pain threshold， thermal pain threshold， and the phosphorylation levels of RIPK1， RIPK3 and MLKL were decreased significantly； the tumor volume， the proportion of bone destruction area， the number of osteoclasts， and the positive expressions of RANK and RANKL were increased/up-regulated significantly （

P

＜0.05）. Compared with the model group， the above pathological changes in the tibial tissues of rats in modified Yanghe decoction low-， medium- and high-dose groups were all alleviated， and all quantitative indicators showed dose-dependent improvement （

P

＜0.05）. After silencing RIPK1， the aforementioned beneficial effects of high-dose modified Yanghe decoction were significantly weakened （

P

＜0.05）.

CONCLUSIONS

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Modified Yanghe decoction can alleviate bone destruction in rats with breast cancer bone metastasis. The above effect is related to the activation of the RIPK1/RIPK3 pathway.