Experimental Study Of Elemene Anti-tumor Effect In HER2-overexpressing Breast Cancer

Objective:Breast cancer is one of the most common malignant tumors in woman.In recent years,the incidence of breast cancer have increased every year and morbidity crowd have displayed the younger in average age trend.In addition,the characteristics with easy to metastasis,high relapse and drug resistance of breast cancer make it become the difficult problem for clinical treatment.At present,breast cancer is mainly divided into four subtypes based on molecular markers,such as luminal A,luminal B,Her-2,basal-like.Patients with Her-2 subtype accounts for 20%~30% and have a high risk of relapse and a poor prognosis.With the deep research on breast cancer,researchers found that there are cancer stem cells in breast cancer,and thought it is one of the important reasons that breast cancer stem cells are the development of drug resistance and tumor metastasis and recurrence.Studies have reported that radiation can induce breast cancer cells to become breast cancer stem cells,the use of chemotherapy drugs can also make enrichment of breast cancer stem cells,so as to develop resistance.In the exploration of correlation between breast cancer stem cells and breast cancer cells,we found over expression of HER2 gene can cause breast cancer stem cell proliferation,and has positive relationship with the expression of bresast cancer stem cell markers ALDH1.Other reports that when HER2 gene is over-expressed in MCF-7cell the number of breast cancer stem cells is increased by 4~5 times.Therefore,overexpression of HER2 gene with drug resistance,metastasis and recurrence is closely related with stem cell-like properties.Elemene is a broad spectrum antitumor drug and efficient to many tumors,such as malignant glioma,leukemia cells,ovarian cancer,stomach cancer and breast cancer.The mainly mechanisms are blocking the cell cycle,inducing apoptosis,inhibiting cell migration and invasion.What is more,elemene can reversedrug-resistance and increase radiotherapy sensitization.Elemene through downregulation Notch-1 reduces angiogenesis in gastric stem cell-like cells.Elemene can inhibit the pluripotency and differentiation and reverse Temozolomide to chemotherapy drug resistance,while the mechanism is still not clear.Elemene can promote apoptosis and increase chemotherapy sensitization in breast cancer,but the mechanism is very little.Therefore,in order to observe elemene on breast cancer and Her-2 overexpressing breast cancer cell proliferation and migration inhibition,we test Elemene on the MCF-7 and MCF-7 HER2 to explore the effect of breast cancer stem cell-like related factors.Methods:(1)We use MTTto detect the proliferation inhibition effect of Elemene on MCF-7 and MCF-7 HER2 and through cell cloning formation assay we verify the proliferation inhibition effect.(2)By wound healing assay we test the migration inhibition ability of the different concentration of Elemene on breast caner cell.(3)Using western blot to detect the expression of HER2 protein,cancer stem cell markers ALDH1,CD44 and CD24,andcancer stem cell related cytokines,we test Elemene and breast cancer cell mutual effect.(4)Sphere formation assay further proves the effect of Elemene on MCF-7 and MCF-7 HER2.Results:(1)Elemene has significant proliferation inhibitory effect on MCF-7 and MCF-7 HER2 cells,and breast cancer cell proliferation inhibition increases with time and drug concentration.Cell cloning formation assay have verified the proliferation inhibition effect.(2)By wound healing assay we find Elemene has inhibitory effect on breast cancer cell migration ability,and with a dose-response relationship.(3)According to the western blot,MCF-7 HER2 in the expression of CD44 and ALDH1 significantly higher than that of MCF-7,while the CD24 lower.Thus,we think MCF-7HER2 possess the characteristics of cancer stem cell.The expression of CD44 and ALDH1 increases but CD24 decreases,and the cancer stem cell related factors Oct4、Nanog、Sox2、KLF4、c-Myc、LIN28A decreases obviously after the Elemene deal with the two kinds of cells.(4)The sphere formation assay demonstrates that the sphere size and number decrease obviously after Elemene deal with the two kinds of cells,although the sphere formation ability of MCF-7 HER2 is higher than MCF-7.Conclusions: In this paper,through the cell proliferation experiment we find the Elemene significantly suppresses MCF-7 and MCF-7 HER2 cells proliferation,and reduce the performance of cell migration activity.The western blot shows that MCF-7HER2 has the characteristics of cancer stem cells,and Elemene can obviously decrease this characteristics,so it proves the Elemene has the very powerful therapeutic effect on the high expression of HER2.