A Study Of NAC1 Inducing Chemoresistance In Breast Cancer Through Regulation Of The RAS-ERK1/2 Pathway

Objective:High expression of nuclear-associated protein 1(NAC1)is associated with the development of several cancers.The aim of this study was to explore and validate the expression profile of NAC1 in breast cancer,and to investigate the effect of high NAC1 expression on breast cancer cell phenotype and drug resistance,and to further predict the pathways regulated by NAC1 leading to chemotherapy resistance.Methods:The expression data in TCGA database were obtained,and the expression characteristics of NAC1 in breast cancer were analyzed and verified by immunohistochemical staining,while the relationship between NAC1 expression and breast cancer prognosis and chemotherapy resistance was analyzed by cox regression.MDA-MB-468 and MDA-MB-453 cell lines with high NAC1 expression were selected for the next experiments.NAC1 was knocked down by si RNA and validated by q RT-PCR,and transcriptome sequencing predicted the pathways regulated by NAC1.The effect of NAC1 expression on cell migration ability was subsequently examined by scratch assay,and cell viability was examined by Cck-8 assay.The effect of NAC1 and ERK1/2 on the sensitivity of breast cancer cells to chemotherapeutic drugs was examined by drug resistance assay.Annexin V FITC/PI double-staining assay was used to detect apoptosis,and the regulatory effect of NAC1 on ERK1/2 phosphorylation was verified by western blot.Results:1.According to the results of database analysis verified by immunohistochemical staining,NAC1 was significantly highly expressed in breast cancer(P < 0.001),and prognostic analysis of breast cancer patients suggested that high NAC1 expression may lead to chemoresistance;2.Based on the transcriptome sequencing results suggesting that NAC1 is associated with ERK1/2 phosphorylation,indicating that NAC1 may regulate the phosphorylation of ERK1/2;3.The measurement of cell proliferation and migration showed that high NAC1 expression promoted the proliferation and migration of breast cancer(P < 0.05),and the detection of drug resistance and apoptosis showed that both high NAC1 expression and ERK1/2 phosphorylation could lead to drug resistance and apoptosis inhibition in breast cancer cells(P < 0.001);4,Western blot assay demonstrated that high NAC1 expression promoted ERK1/2phosphorylation by upregulating RAS(P< 0.05),which indicated that the NAC1-RAS-ERK1/2 pathway was involved in the drug resistance process mediated by NAC1.Conclusion:1.NAC1 is significantly overexpressed in breast cancer and leads to chemotherapy resistance in breast cancer;2.High expression of NAC1 promoted the proliferation and migration of breast cancer;3.NAC1 inhibits apoptosis of breast cancer cells through the RAS-ERK1/2 pathway and leads to multidrug chemoresistance.