C/EBP ζ targets to neutrophil gelatinase-associated lipocalin (NGAL) as a repressor for metastasis of MDA-MB-231 cells

Abstract

Breast cancer is a leading cause of morbidity in women worldwide. neutrophil gelatinase-associated lipocalin (NGAL), a useful biomarker of ER negative (ER(-)) breast cancer, promotes local tumor invasion and lymph node metastasis. We first identified the distinctive expression of NGAL in two breast cancer cell lines MCF7 and MDA-MB-231 cells, and then confirmed NGAL as a critical inducer of metastasis. Finally, the transcriptional factor CCAAT enhancer-binding proteins ζ (C/EBP ζ) was overexpressed in MDA-MB-231 cells. Consistent with the effect of NGAL knockdown, C/EBP ζ overexpression caused the significant changes that could prevent cell metastasis. C/EBP ζ overexpression induced a strong decrease in NGAL and matrix metalloproteinases (MMPs) expressions as determined by quantitative real time PCR and Western blotting. To identify the potential role of C/EBP ζ on regulating of NGAL in breast cancer, we established the dual-luciferase reporter assay for NGAL in MDA-MB-231 cells cotransfected with C/EBP ζ. Promoter reporter assays determined that C/EBP ζ directly repressed the human NGAL gene promoter activity by inhibiting the NGAL transcription. Taken together, this work identified that the C/EBP ζ overexpression downregulated NGAL to inhibit migration and invasion of breast cancer, which could be used as a novel strategy for breast cancer therapy.