Significance Of Neutrophil Gelatinase-Associated Lipocalin Expression In Esophageal Squamous Cell Carcinoma

NGAL (Neutrophil gelatinase-associated lipocalin), a member of the lipocalin family, was originally found as a protein stored in specific granules of the human neutrophil. Our previous work have identified that NGAL, was overexpressed in the progression of malignant transformation from human immortalized esophageal epithelial cell line SHEE to esophageal carcinoma cell line SHEEC by using cDNA microarray. This suggested that NGAL might be involved in the carcinogenesis of ESCC (esophageal squamous cell carcinoma). Elevated NGAL expression was observed in several types of cancers recently. However, the characteristics of NGAL expression in neoplasms are still unknown. The aim of this study is to demonstrate the expression pattern of NGAL in ESCC and the study would provide significant clues to further explore the roles of NGAL in the formation and progression of neoplasms. Materials and methods:NGAL expression in 81 paraffin sections, including ESCC, normal mucosa, simple hyperplasia, dysplasia, and 73 fresh specimens of ESCC were analyzed by immunohistochemistry, western blot, gelatin zymography and image analysis techniques. The expression level of NGAL in 5 esophageal carcinoma cell lines was also examined by immunofluorescence and western blot. Results:1. In immunohistochemical study, only weak positive signal was presented within restricted cytoplasmic area in normal esophageal epithelium. While in ESCC and dysplasia of esophagus, a whole-cytoplasmic expression of NGAL could be observed.2. In western blot study, NGAL expression level was significantly higher in ESCC than that in normal mucosa (P=0.030) with diverse expression pattern.3. No significant association was observed between NGAL expression and cell proliferation by detecting the expression level of PCNA and NGAL in the same specimens with western blot technique (P=0.400).4. The enzymic activity of NGAL/MMP-9 complex was much higher in ESCC than that in normal mucosa in zymography analysis (P<0.0001).5. Through analyzing the relationship between NGAL expression and clinicopathologic...