The Research On The Expression Of BRCA1/2 And The Development Of Immunosuppressive Microenvironment In Breast Cancer

Objectives: Breast cancer susceptibility gene1(BRCA1)and breast cancer susceptibility 2(BRCA2)are the earliest discovered and most studied genes,which could repair DNA through homologous recombination,and prevent the occurrence and progress of breast cancer.Besides,the immune status of microenvironment in breast tumor is also closely related to the prognosis of breast cancer patients.However,the relationship between BRCA1/2 mutation and the immune microenvironment in breast cancer is not clear.The purpose of this topic is to state the correlation between BRCA1/2 mutation,BRCA1/2 protein expression and the immune status of microenvironment in breast cancer,then further discuss its influence on the prognosis of breast cancer patients.Methods: 1.The clinicopathologic data of 77 cases of patients with breast cancer in Tianjin Medical University Cancer Institute and Hospital from January 2014 to September 2016 was collected.All patients were women,who were eliminated distant metastasis,such as bone,liver,lung before surgery.And the surgical methods included radical resection,modified radical mastectomy,and breast-conserving operation,all surgical specimens were confirmed as breast cancer using postoperative pathological examination.Besides,all patients accepted standardized treatment,such as chemotherapy and radiation,endocrine therapy as well as target therapy based on the clinical guidelines.2.The DNA of 32 cases of breast cancer patients was extracted through peripheral blood of breast cancer and sequenced using the second generation sequencing technology,and the whole-exome of BRCA1/2 was detected through Amplicon sequencing method,then summarize the mutation of BRCA1/2.3.77 cases of paraffin-embedded breast cancer tissues and para-carcinoma breast tissue were collected in Tianjin Medical University Cancer Institute and Hospital,the BRCA1/2 protein expression was tested through immunohistochemistry.Besides,the distribution of CD4+T cell,CD8+T cell,B cell,CD56+T cell, macrophage,Treg cell was also investigated by immunohistochemistry,respectively.4.32 cases of fresh breast cancer tissues were collected treated in Tianjin Medical University Cancer Institute and Hospital,and the proportion of CD3+T cell,CD4-+T cell,CD8+T cell was tested through flow cytometric method,meanwhile,the expression of Programmed death-1(PD-1),Programmed death ligand-1(PD-L1),Cytotoxic T lymphocyte-associated antigen-4(CTLA-4),Lymphocyte activation gene-3(LAG-3)of breast cancer cells was detected by cytometric method.5.The association between BRCA1/2 protein expression of breast cancer and BRCA1/2 mutation,clinicopathologic feature of breast cancer patients,as well as immune status of microenvironment in situ was analyzed through SPSS 20.0.Result: 1.In the 32 cases of breast cancer patients,the germline mutation of BRCA1/2 was inconsistent with the BRCA1/2 protein expression.2.Immunohistochemistry showed that the proportion of T lymphocytes,B lymphocytes,Natural killer cells(NK cells),macrophage,Treg cells in breast cancer patients with negative expression of BRCA1/2 protein was higher than patients with positive expression of BRCA1/2 protein,and the difference was statistically significant.(P<0.05).3.Flow cytometric method showed that the proportion of CD4+T cells,CD8+T cells in breast cancer patients with negative expression of BRCA1/2 protein was higher than patients with positive expression of BRCA1/2 protein,and the difference was statistically significant.(P<0.05).Besides,the expression of PD-1,CTLA-4,PD-L1 of CD3/4+ T cells in breast cancer patients with negative expression of BRCA1/2 protein was higher than patients with positive expression of BRCA1/2 protein(P<0.05),and the expression of PD-L1 of CD3/8+ T cells in breast cancer patients with negative expression of BRCA1/2 protein was higher than patients with positive expression of BRCA1/2 protein(P<0.05).4.The BRCA1 protein expression of breast cancer tissue was significantly correlated with family history of breast cancer patients(p=0.044),local lymph node metastases(p=0.032),and TNM staging(p=0.003).The BRCA2 protein expression of breast cancer tissue was significantly related to local lymph node metastases(p=0.014)and molecular subtyping(p=0.009).Conclusions: 1.The germline mutation of BRCA1/2 was inconsistent with the BRCA1/2 protein expression.2.The proportion of local lymph node metastases in breast cancer patients with negative expression of BRCA1/2 protein was higher than patients with positive expression of BRCA1/2 protein,which suggested poor prognosis.3.The function of immune cells was suppressed in breast cancer patients with negative expression of BRCA1/2 protein,then their antitumor immunity was restrained.