Expression Of B7-H1 Affecting The Chemotherapeutic Sensitivity Of Breast Cancer

Objectives: To explore the expression of B7-H1 in breast cancer affecting the sensitivity to chemotherapy and whether chemotherapy drugs inducing the B7-H1 expression level changes of breast cancer cells could affect the sensitivity of the tumor cells to chemotherapy.Methods: 1, Silenced expression of B7-H1 in MDA-MB-231 cell via stable short hairpin RNA. MDA-MB-231 cells and B7-H1 si RNA-MDA-MB-231 cells was treated respectively by epirubicin(0.8 μg /m L) and docetaxel(1.0 μg/m L) for 72 hours, then determined cell proliferation by cell counting kit-8 and detected the percentage of apoptosis cells by flow cytometry. 2, Using Bard automatic biopsy gun biopsy 32 patients with breast cancer, and obtaining tissue strips that were confirmed breast cancer by pathology. All patients accepted radical operation after 4-6 cycles of chemotherapy. Detecting the change of B7-H1 protein level from the primary lesion before and after neoadjuvant chemotherapy using immunohistochemical method and Western Blot. Studing the relation bestween B7-H1 expression level and B7- H1 expression changes before and after chemotherapy with the tumor cells to chemotherapy sensitivity.Results: 1, MDA-MB-231 cells and B7-H1 si RNA-MDA-MB-231 cells was treated respectively by epirubicin and docetaxel for 72 hours. MDA-MB-231 cells proliferation ability was higher than B7-H1 si RNA-MDA-MB-231 cells, but MDA-MB-231 cells apoptosis levels significantly lower than B7-H1 si RNA-MDA-MB-231 cells. So the expression of B7-H1 could reduce the sensitivity of breast cancer cells to chemotherapy drugs. 2, There were 4 patients from B7-H1 lower expression to high expression. After chemotherapy, there are 13 patients(including the previous 4 cases) B7-H1 expression was upregulated compared with before neoadjuvant chemotherapy, and 19 patients have no obvious changes. So neoadjuvant chemotherapy can influence B7-H1 expression in breast cancer tissue. 3, All patients were underwent efficacy evaluation after neoadjuvant chemotherapy. After neoadjuvant chemotherapy, There were 21 cases with high expression of B7-H1 as high expression group and 11 cases with low expression as low expression group. The owrall response rate of high expression group had no statistical significance compared with low expression group. The complete clinical response of high expression group was obviously lower than low expression group(p<0.05). The expression of B7-H1 in breast cancer tissue that affect neoadjuvant chemotherapy curative effect. 4, After chemotherapy, there are 13 patients B7-H1 expression was upregulated compared with before neoadjuvant chemotherapy as upregulate group, and 19 patients have no obvious changes as stable group. The owrall response rate of upregulate group was lower than stable group, but had no statistical significance(p=0.06). The complete clinical response of upregulate group had no statistical significance compared with stable group.Conclusions: Silencing B7-H1 of breast cancer cells could increase the apoptosis mediated by chemotherapy drugs. Abnormal expression of B7-H1 in breast cancer could reduce the sensitivity of breast cancer cells to chemotherapy drugs. Neoadjuvant chemotherapy could upregulate the expression of B7-H1 in tumor tissue and Reduce the the efficacy of chemotherapy drugs, but lack of statistical difference. So the immune costimulatory molecule B7- H1 is associated with breast cancer drug resistance.