Expression of IMP3 as a marker for predicting poor outcome in gastroenteropancreatic neuroendocrine neoplasms

The aim of the present study was to investigate the expression and clinical significance of oncofetal protein insulin-like growth factor (IGF) II mRNA-binding protein 3 (IMP3) in the differentiation of gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN). A total of 162 patients who were diagnosed with GEP-NEN, and who underwent surgical or endoscopic resection from January 2006 to March 2013, were enrolled in the study, including 85 cases of grade (G)1 neuroendocrine tumors, 40 cases of G2 neuroendocrine tumors, 28 cases of G3 neuroendocrine carcinomas and 9 cases of mixed stage adenoneuroendocrine carcinomas. The clinical and pathological data were recorded for analysis. The expression of IMP3, cluster of differentiation (CD)44, IGF1 receptor (IGF1R) and matrix metalloproteinase (MMP)2 was determined by immunohistochemistry. SPSS 13.0 software was used for data processing and analyses, and P<0.05 was used to determine significance. Oncofetal protein IMP3 exhibited a high expression rate (74.69%) in GEP-NEN. IMP3-positive cases demonstrated significantly decreased overall and disease-free survival times, as compared with IMP3-negative cases (P=0.012). Overexpression of IMP3 was correlated with tumor grade, clinical stage, tumor size and poor prognosis (all P<0.05). Therefore, patients with overexpressed IMP3 had a poorer prognosis (P<0.01); COX regression analysis revealed that the overexpression of IMP3, the tumor grade, tumor size and metastasis of GEP-NEN were each associated with the clinical outcomes. The results also indicated that the expression rates of CD44, IGF1R and MMP2 in GEP-NEN were 19.75, 53.7 and 55.56%, respectively. While it was negatively associated with the expression of CD44 (r=-0.131; P=0.096), the expression of IMP3 was positively correlated with the expression of IGF1R and MMP2 (r=0.288, P<0.01; r=0.208, P=0.008). In addition, the expression levels of IGF1R and MMP2 were positively associated (r=0.687; P<0.01). In conclusion, high IMP3 expression levels were determined to be associated with a high disease stage in patients with GEP-NEN, thus it may serve as a predictor for metastasis and poor clinical outcomes in GEP-NEN.