Expression of insulin-like growth factor II mRNA-binding protein 3 in human esophageal adenocarcinoma and its precursor lesions

Context.-Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is an oncofetalprotein highly expressed in fetal tissue and malignant tumors but only rarely within adult benign tissues. The expression of IMP3 in esophageal adenocarcinoma (EAC) and its precursor lesions including distinctive type Barrett mucosa (BM, intestinal metaplasia) and esophageal columnar dysplasia (ECD) is largely unknown. Objective.-To characterize the patterns of IMP3 expression in EAC and its precursor lesions. Design.-Samples from 132 casesof EAC, 28 cases of ECD (16 high-grade dysplasia and 12 low-grade dysplasia cases), 28 cases of BM without dysplasia, and 138 cases of nonneoplastic esophageal mucosa without dysplasia or BM within formalin-fixed, paraffin-embedded tissue microarray blocks were examined. Tissues were stained with mouse monoclonal anti-IMP3 antibody. The intensity (1-3+)and percent (0%-100%) of positive cytoplasmic and/or membranous IMP3 staining cells were determined. Results.-Most of EAC cases (93 of 132; 70%) showed cytoplasmic and membranousIMP3 staining. Poorly and moderately differentiated EAC showed statistically significant higher IMP3 expression compared with well-differentiated EAC (P < .001). A subset of ECDcases (7 of 28; 25%) was positive for IMP3, including 3 low-grade dysplasia cases (focal1+IMP3 staining) and 4 high-grade dysplasia cases (more diffuse 1-2+ IMP3 staining). No IMP3 staining was observed in any nonneoplastic esophageal mucosa and BM tissues without dysplasia. Conclusions.-This study suggests that IMP3 may play a role in the carcinogenesisof EAC and has diagnostic utility in differentiating neoplastic and nonneoplastic lesionsof the esophagus.