Bushenzhuanggu Medicine On Rat Breast Cancer Bone Metastasis Model

Bone metastasis is the most common distant metastasis from breast cancer.In advanced breast cancer,about 65%-80%patients are suffering from bone metastasis,which decreased their quality of life.Thus, comprehensive treatment was adopted to control bone metastasis, reinforcing kidney and strengthening bone of Traditional Chinese medicine(TCM) is a effective therapy,the mechanism should be researched.Objective:According to the TCM theory,kidney controlling bone,TCM herbs including Herba Epimedii,Rhizoma Drynariae and Fructus Psoraleae,which has the function of reinforcing kidney and strengthening bone were given to rats with bone metastasis.Osteoclast activity was determinated as breakthrough point,effects on bone lesion and bone pain of the rats was observed.Methods:Female Sprague-Dawley rats were divided into 6 groups,rats of sham operation group were Intra-tibial injected normal saline,while others were inoculated the MRMT-1 cells to develop model of bone metastasis from breast cancer.Herba Epimedii,Rhizoma Drynariae, Fructus Psoraleae,pure water and Zoledronic acid was given to different group respectively to observe the effects.On day 19 after the injection of MRMT-1,behavior of von Frey hair stimulated 50%Paw withdrawal threshold(50%PWT),difference of weight bearing between hind paws and thermal withdrawal latency(TWL) were tested in all groups. All rats were killed on day 21,volume of tumors were measured,the uterus coefficients were calculated,serum and tibias were collected: level of estradiol(E₂) and bone alkaline phosphatase(BALP) in serum was detected by ELISA method.Real-time RT-PCR technique was used to examine mRNA expressions of parathyroid hormone related protein(PTHrP) in half of the tibias,the others were used to evaluate the bone lesions by radiological analysis,quantitative measurement of bone mineral density(BMD) and bone mineral capacity(BMC),then the tissues were made into paraffin sections,through HE stain,tartrate-resistant acid phosphatase(TRAP) stain and immunohistochemistry to observe the bone pathological changes,count TRAP stained osteoclasts and semi-quantitatively measure expressions of proliferating cell nuclear antigen(PCNA),osteoprotegerin(OPG),receptor activator of nuclear factor-κB ligand(RANKL) and estrogen receptor(ER). Results:The model showed feature of mixed metastasis,dominated by osteolytic bone lesion,manifested as over activation of osteoclasts, excessive bone resorption and bone pain.Compared to model group,BMD was enhanced by Herba Epimedii and Zoledronic acid,radiological analysis was improved by Zoledronic acid, BMC of all treatment groups showed tendency to increase,but no statistical difference.Above results indicated that all treatment can relieve the osteolytic bone lesion induced by bone metastasis.Osteoclast activity were decreased in all treatment groups,and increased expression of OPG made RANKL/OPG ratio drop,PTHrP mRNA was no significance between treatment groups and model group.So,TCM herbs of reinforcing kidney and strengthening bone and Zoledronic acid showed effect of blocking the excessive activation of osteoclasts,and it's the core link in osteolytic bone defect.There was no change in the level of uterus coefficient,serum E₂ level, didn't show estrogenic effect significantly,it's not a operating pathway of bone protection.Tumor volumes were decreased by Fructus Psoraleae,and other treatment groups showed tendencies to reduce the volumes than model group,but no significance,so did PCNA level,revealed that all the TCM herbs had the effect of tumor inhibiting in different degree.As regards behavior tests,50%PWT of treatment groups were higher than model group,differential values between hind paws weight bearing of Herba Epimedii and Fructus Psoraleae group were lower than models. Herba Epimedii also prolonged TWL,showed that the TCM herbs can improve the threshold of pain,and relieve pain caused from bone metastasis. Conclusion:TCM herbs of reinforcing kidney and strengthening bone showed effect of alleviating bone destruction and bone pain induced by bone metastasis,the core link is to block the excessive activation of osteoclasts.The major mechanism can be derived from increased OPG level to decrease the ratio between RANKL and OPG,the function of inhibiting tumor growth maybe another reason.In a word,reinforcing kidney and strengthening bone of TCM is a effective therapy to bone metastasis from breast cancer.