IMP3 is a novel biomarker to predict metastasis and prognosis of tongue squamous cell carcinoma.

: Insulinlike growth factor II mRNA-binding protein 3 (IMP3) is a newly identified mRNA-binding protein that is involved in embryogenesis and carcinogenesis of some malignant tumors. The aim of this study was to investigate the clinicopathologic significance of this protein in tongue squamous cell carcinoma (SCC). The expression of IMP3 in 65 samples of tongue SCC and 27 cases of oral leukoplakia (OL) was evaluated by immunohistochemistry. These expression levels were correlated with clinical and pathologic features as well as death from tongue SCC. Weak immunohistochemical stain for IMP3 was identified in all 19 cases of OL with mild dysplasia, and no immunohistochemical reactivity was found in 8 cases of OL without dysplasia. Positive immunohistochemical stain for IMP3 was identified in 50 cases (77%) of SCC; among them, weak staining was identified in 33 cases (51%) and intermediate staining in 17 cases (26%). To compare the expression of IMP3 in tongue SCC and OL, stronger immunohistochemical reactivity was found in tongue SCC (P < 0.05). Stronger expression of IMP3 was found to be associated with lymphoid metastasis (P < 0.05) and patient poor outcome (median survival time of 40 months in the negative and weak expression group vs 10 months in the intermediate expression group; P < 0.05). This study suggests that the increase in IMP3 expression in tongue leukopathia and SCCs may play a role in the carcinogenesis and tumor metastasis of tongue SCCs. Insulinlike growth factor II mRNA-binding protein 3 could be a novel prognostic indicator for patients with tongue SCCs.