Expression Of Autophagy Protein In Triple Negative Breast Cancer And The Effect Of Autophagy Inhibitor Combined With Chemotherapeutic Drugs On Triple Negative Breast Cancer Cells

Background and ObjectiveBreast cancer is currently the most common malignant tumor in women,and it is also one of the main lethal diseases,which has a serious impact on the physical and mental health of women.Triple negative breast cancer(TNBC)is one of the subtypes of breast cancer that does not express estrogen receptor,progesterone receptor and human epidermal growth factor receptor-2.It is highly invasive,with high histological grade and prone to metastasis.Compared with other subtypes,TNBC has higher recurrence rate,higher mortality rate and worse prognosis.Due to the lack of expression of ER,PR and Her2,molecular targeted therapy and endocrine therapy can not effectively treat this type of breast cancer,only by using systemic chemotherapy can the disease be alleviated to a certain extent.Chemotherapy resistance is the main factor of poor response and low overall survival rate.Therefore,it is very important to find effective methods to improve the sensitivity of tumor cells to chemotherapeutic drugs.Autophagy is a process by which intracellular substances are degraded by lysosomes and plays a key role in maintaining cell homeostasis.In recent years,many studies have shown that autophagy is closely related to tumor cells resistance.Many anti-tumor drugs can induce autophagy in tumor cells,which makes tumor cells resistant.Docetaxel is a commonly used drug for the treatment of breast cancer in clinical practice.Drug resistance is a major obstacle in clinical application.It has been found that inhibition of autophagy in some tumors such as prostate cancer can increase the sensitivity of tumor cells to docetaxel.Chloroquine(CQ)can increase the sensitivity of tumor cells to chemotherapeutic drugs by inhibiting the binding of autophagosomes to lysosomes to block the late process of autophagy degradation.In triple-negative breast cancer,whether CQ can increase the sensitivity of TNBC cells to DTX has not been reported.Therefore,the purpose of this study was to investigate the effect of autophagy inhibitor CQ combined with chemotherapeutic drug DTX on apoptosis of MDA-MB-23 1 cells.MethodsIn this study,immunohistochemical staining was used to detect the expression of Bec in1 and p62 in TNBC tissues.Triple-negative breast cancer MDA-MB-231 cells were used as the study group,which were divided into blank control group,chloroquine group,docetaxel group,docetaxel+chloroquine group.The IC50 value of docetaxel in MDA-MB-231 cells was measured by CCK8,and this concentration was used as the subsequent experimental concentration.The cell viability was detected by CCK8,and the apoptosis was detected by flow cytometry.The expression of autophagy-related protein LC3B was detected by western blot.Results1.Immunohistochemical staining showed that the autophagy-related protein Bec in1 was overexpressed in paracancerous normal tissues and low in TNBC tissues(P<0.01);p62 was overexpressed in TNBC tissues and low in paracancerous normal tissues(P<0.01).2.The results of CCK8 showed that the cell viability of MDA-MB-231 gradually decreased with the increase of docetaxel concentration,indicating that docetaxel had inhibitory effect on MDA-MB-231 cells.The IC50 value of docetaxel for 48 h was 21.5nM.3.CCK8 results also showed that compared with the control group,the cell viability of CQ group,docetaxel group,docetaxel combined with CQ group decreased(P<0.05);Compared with the docetaxel group,the cell viability was significantly lower in the docetaxel combined with CQ group(P<0.05).4.The results of apoptosis by flow cytometry showed that compared with the control group,the apoptosis rate of CQ group,docetaxel group,docetaxel combined with CQ group increased significantly(P<0.05);Compared with docetaxel group,the apoptosis rate of docetaxel combined with CQ group was significantly higher(P<0.05).5.Western blot results showed that the expression of LC3B ? protein in docetaxel combined with CQ group was significantly increased compared with CQ group(P<0.05),suggesting that docetaxel may induce autophagy in MDA-MB-231 cells.Conclusions1.Abnormal expression of autophagy-related proteins Beclinl and p62 in TNBC tissues suggests that autophagy may be involved in the development of TNBC.2.The results of this study showed that autophagy inhibitor CQ combined with DTX can reduce the cell villiably of triple-negative breast cancer MDA-MB-231 cells and increase apoptosis,suggesting that autophagy inhibitor CQ can increase the sensitivity of MDA-MB-231 cells to DTX.It may be exerted by inhibiting DTX-induced autophagy.This study provides a reference basis for improving the treatment of triple negative breast cancer.