The Study Of Breast Cancer Model Induced By7,12-dimethylbenz(a)anthr Acene In Mice

Breast cancer is now widely recognized as women’s second-largest killer, and animal model ofbreast cancer has important implications for etiology research and treatment, drug screening and evaluation.7,12-dimethylbenz（a）anthracene （DMBA）-induced rat mammary carcinoma model is comparativelymature, but little research for mouse mammary carcinoma model building is reported. Our purpose is toexplore whether DMBA can induce mammary carcinoma in mice successfully and provide a good animalmodel for the pathogenesis study of breast cancer and evaluation of Chinese medicine treatment’scharacteristics and advantages.In this study, C57BL/6mice were orally administrated with DMBA （50mg/kg wt） dissolved inolive oil once a week for five weeks. The tumor latency, incidence rate, mice survival, appearance, bodytemperature, spontaneous activity, external auricle microcirculation and and hemorrheologic index wereobserved to evaluate the changes of medical signs in carcinogenic process. Histology section HE stainingand SABC immunohistochemical staining were used to observe the morphology and TGF-β1expressionchanges in mouse mammary glands abtained in different periods after induction. Meanwhile these sectionswere compared with clinical ones to evaluate the pathological similarity and difference between them. Byadministrating the mice with warm prescription whose mian drug is aconite or cold prescription whose isdandelion, we evaluated both cold and heat treatments for breast cancer in mice with the detections ofenergy metabolism indicators (erythrocytic Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase activities) levels,serum hoemones （estradiol, progesterone） levels, serum cytokines and receptors （NGF, TrkA, BDNF, TrkB,bFGF, TGF-β1, PAF） levels, serum extracellular matrix and relative factors （TIMP-1, MMP-9, LN, COL â… , â…¡, Ⅲ） levels. MTT, soft agar cloning, BrdU immunofluorescence, Janus green staining, gelatinzymography and Western-blot were used to observe the proliferation ability and mitochondrial changes,MMPs and TGF-β1expression changes of QSG-7701cells as induced with DMBA and verified themechanism of DMBA-induced transformation of normal cells.Results showed that the model mice appeared gradually aversion to cold and preference forwarmth, cureled up and drow siness, body temperature dropped and auricle microcirculation disordered,whole blood viscosity and erythrocyte aggregation index rised, erythrocyte ATPase activity decreased,serum alcohol and progesterone increased as the administration time prolonged. After drug’s interventionwe found that the warm prescription not only significantly improved the situation above, but also reducedthe levels of serum cytokines and extracellular matrix, prolonged mice survival time and inhibited tumorgrowth. At last we found these twice inductions have similarity in tumor latency, incidence rate andsurvival curves.Histology section HE staining showed that DMBA induced mouse to get breast cancer is througha dynamic process from normal to hyperplasia→atypical hyperplasia→cancer→invasive cancer, which issimilar to human breast cancer development. Immunohistochemical staining showed that DMBA couldinduce TGF-β1over expression in the cytoplasm of mouse mammary carcinoma and it is positively relatedto tumor malignant degree, which is same with human breast cancer.Invitro results showed that DMBA exhibited a dose-dependent inhibition to QSG-7701cells, andIC50was42.5μg/mL. Meanwhile50-100μg/mL DMBA could significantly change QSG-7701cells’morphology. Comparing with normal liver cells, DMBA-induced liver cells had significantly improved thesoft agar cloning formation ability and the number of positive cells incorporated with BrdU, andmitochondrial dysfunctioned, increased in the cells. The SDS-PAGE also showed an obvious difference of protein expression between them and the latter existed some similarity with LLC and4T1cells. Besides theinduced liver cells had obviously improved the activities of MMP-2and MMP-9in gelatin zymography andTGF-β1expression in Western blot.These results suggest that the approach of administrating C57BL/6mice orally with DMBA50mg/kg once a week for five weeks can successfully establish a mouse breast cancer model, and thismodel is similar with human breast cancer, which can be used in breast cancer pathogenesis and Chinesemedicine treatment researches in further study.