IMP3 Predicts Invasion and Prognosis in Human Lung Adenocarcinoma

Abstract

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is an oncofetal protein associated with several aggressive and advanced cancers. Whether IMP3 can predict invasion, and prognosis in patients with human lung adenocarcinoma (LAC) remains unclear. Ninety-five LAC and 75 non-tumor lung tissue samples were included in a tissue microarray. IMP3 expression was assessed by immunohistochemical examination. Correlation between IMP3 expression levels, clinicopathological characteristics, and overall prognosis was evaluated. In a separate in vitro study, RNA interference method was applied for knockdown of IMP3 gene in human LAC cell lines. Invasive potential of LAC cells was then evaluated by transwell migration assay. IMP3 immunoreactivity was observed in 39 out of 95 (41.1 %) LAC patients, but not in non-tumor lung tissues. IMP3 expression levels were closely associated with histological grade (P = 0.037), TNM stage (P = 0.034), and lymph node metastasis (P = 0.011). Patients presenting with positive IMP3 expression (P = 0.000), an advanced TNM stage (P = 0.000), and lymph node metastasis (P = 0.001) had a worse overall survival, compared to those lacking these characteristics. Both IMP3 expression (hazard ratio [HR], 2.310; 95 % confidence interval [CI] 1.192-4.476; P = 0.013) and TNM stage (HR 2.338; 95 % CI 1.393-3.925; P = 0.001) were independent predictors of poor prognosis. The invasive potential of LAC cells was significantly inhibited by IMP3 knockdown. IMP3 appears to play an important role in tumor invasion in patients with LAC and may serve as a useful prognostic biomarker in these patients.