Tiandi Powder Intervention On Breast Cancer Invasion And Metastasis And Its Mechanism

Breast cancer,one of the most common cancer in female patients worldwide,is considered as a highly metastatic cancer accounting for high mortality rate every year.Breast is not the vital organ to maintain human life activity and breast cancer in situ is not fatal.However,the breast cancer cells lost of normal cell characteristics have lower adhesiveness and spread the whole body through the blood or lymph system to form metastases.In spite of many cancer therapeutic methods have been developed,the effect of which is not satisfied,these have little beneficial effects on HER-2 negative breast cancers.Similarly,chemotherapy with trastuzumab is recommended for HER2-positive patients with breast carcinoma,not HER-2 negative patients.Therefore,it is vital to find a reliable and effective therapeutic method for breast cancer.It is shown that epidermal growth factor receptor（EGFR）and HER-2 are the same family membrane protein receptor,and they play an important role in the development of clinical target therapy.Many strategies for targeting EGFR and HER-2 have been developed,but several such strategies are successfully in clinical use.Moreover,accumulating evidence indicates that epidermal growth factor（EGF）/EGFR induces EMT and contributes to the acquisition of metastatic capabilities and its downstream signaling pathways,an EGFR-Akt-mTOR-dependent axis,activate in diverse carcinoma cells.Therefore,searching a novel efficacious therapeutic agent targeting EGF and EGFR for treating breast cancer should be necessary.Tetraarsenic oxide（As₄O₆）,an arsenic compound,is used in Korea as an anti-tumor substance for malignancies treatment.In Korea,As₄O₆ has been used in folk remedy for cancer management since the late 1980s.In recent decades,it is reported that As₄O₆ exerts significant anticancer effects on different cancers in vitro,including cervical,colon,glioma,and leukemia.The beneficial impact of As₄O₆ on angiogenesis,radiotherapy sensitivity and combination therapy has been noted.Though several studies referring to the anticancer effects of As₄O₆ have been performed,there is merely a paper demonstrated that As₄O₆ had the anticancer effects on human breast cancer cells through NF-κB signaling pathway.However,the mechanism and its inhibitory effects of As₄O₆ on breast cancer cells invasion and migration has not been clearly yet.Therefore,the purpose of the present study was to evaluate the inhibitory effect of As₄O₆ on invasion and migration and to elucidate the molecular mechanism involved.We searched the references and chose MCF-7,MDA-MB-231,MDA-MB-453 and SKBR3 cells to do the research.In the research,we used MTT,wound healing assay,Transwell invasion and migration assay,adhesion assay,RT-PCR,western blotting and animal experiment to explore the mechanism.The methods and results of this study are as follows:（1）The treatment of As₄O₆ inhibited cell proliferation of MCF-7 cells.Also,it suppressed the invasion and migration of breast cancer cells,especially for the inhibition of EGFR and mTOR phosphorylation.Meanwhile,EGF-induced the protein expression of p-EGFR was suppressed by As₄O₆ in the cell lines.The present data suggests that the inhibitory effects of As₄O₆ on the invasion and migration of breast cancer cells via negatively regulating the EGFR-mediated signaling pathway.（2）The treatment of As₄O₆ inhibited cell proliferation of MDA-MB-231 cells in a dose-and time-dependent manner.Also,it suppressed the invasion and migration of breast cancer cells,resulted in the reduction of MMP-2 and MMP-9 expression,especially for the inhibition of EGFR phosphorylation.Meanwhile,EGF-induced the protein expression of p-EGFR was suppressed by As₄O₆ in both cell lines.The present data suggests that the inhibitory effects of As₄O₆ on the invasion and migration of breast cancer cells via negatively regulating the EGFR-mediated signaling pathway.（3）The treatment of As₄O₆ inhibited cell proliferation of MDA-MB-453 cells in a dose-and time-dependent manner.After EGFR-induced,the capacity of invasion and migration of MDA-MB-453 cells improved.However,after interfering by As₄O₆,the capacity of invasion and migration of MDA-MB-453 cells declined.Compared with Lapatinib,the effect of As₄O₆ on the inhibition of invasion and migration of MDA-MB-453 cells was better.And the combination of As₄O₆ and Lapatinib could improve the inhibitory effect,which was better than either As₄O₆ or Lapatinib single use.（4）The treatment of As₄O₆ inhibited cell proliferation of SKBR3 cells in a dose-and time-dependent manner.The results demonstrated that As₄O₆ could efficiently inhibit the migration and invasion of SKBR3 cells,the HER-2 positive breast cancer cells,and the adhesion of SKBR3 cells was decreased after As₄O₆ treatment.The mechanism revealed that As₄O₆ anticancer efficacy was related to HER-2/EGFR pathways.As₄O₆ exerted its inhibitory effects on migration and invasion in HER-2 positive breast cancer cells by regulating the factors（EGFR,HER-2,Akt,MMP-9）in HER2/EGFR signaling pathway and other key molecules.In conclusion,the present study indicated that As₄O₆ inhibited the invasion and migration process of HER-2 positive breast cancer SKBR3 cells by negatively regulating the HER-2/EGFR-mediated signaling pathway.Above all,As₄O₆ had the better effect on MDA-MB-321 cells,which was sensitive to As₄O₆.（5）As₄O₆ could inhibit the growth of tumor in BABL/C nude mice,the inhibitory rate could achieve 40%,and the weight of nude mice did not appeared the significant loss（P>0.05）.It indicated that the toxicity of As₄O₆ is lower and safety is better.