Abstract: Objective We studied the biological function of NFKBIZ in breast cancer and analyzed its clinical significance in combination with clinical data to discuss its potential value of diagnosis. Methods Quantitative real-time PCR（qPCR） was used to identify the expression of NFKBIZ in cells and in tissues. Western blot assay and immunohistochemistry were used to detect the IκBζ expression in tissues. siRNA was constructed and transfected into breast cancer cells for colony formation and transwell migration assay to detect the effect of NFKBIZ expression on the proliferation and migration; ROC curve was performed to analyze the diagnostic efficacy of NFKBIZ in breast cancer; Statistical analysis was determined the correlation between NFKBIZ expression level and pathological parameters of breast cancer.Results qPCR showed that the expression of NFKBIZ on MDA-MB-231 cells was significantly higher than that on MCF-7 cells （P<0.05）,and its expression in breast cancer tissues was significantly higher than that in para-cancerous tissues（P<0.05）. The expression level of IκBζ protein in breast cancer was significantly higher than that in benign breast disease tissues. The area under the ROC curve （AUC） of NFKBIZ was 0.810, with a cutoff value of 1.418,showing a sensitivity of 81.8%, and a specificity of 90.9%. The expression level of NFKBIZ was significantly correlated with tumor size and patient age （P<0.05）,but it had no significant correlation with TNM stage,pathological type,and lymph node metastasis （P>0.05）.Conclusion NFKBIZ plays an important role in the development of breast cancer and may become a novel biomarker for clinical diagnosis.

Key words: Breast cancer, NFKBIZ, IκBζ, ROC, Diagnostic value