Immunohistochemical Expression of IMP3 in Cutaneous Basal Cell Carcinoma

Background. Insulin-like growth factor-II mRNA-binding protein 3 (IMP3) is an oncofetal protein upregulated in tumor cells during carcinogenesis. It has been linked to adverse clinical outcome in many malignancies. This study was aimed to evaluate an immunohistochemical expression status of IMP3 in cutaneous basal cell carcinoma (BCC) and to correlate it with the Ki-67 index values. Methods. Biopsy specimens from 32 cases of BCC were enrolled into this analysis. All samples were immunohistochemically stained for IMP3 (Clone 69.1) and Ki-67 antigen (Clone MIB-1). Results. IMP3 showed a weak expression in 11 (34.4%) cases, a moderate expression in 11 (34.4%) cases, a strong expression in 5 (15.6%) cases, and negative staining in 5 (15.6%) cases. Among seven BCCs exhibiting aggressive-growth features, all but one showed weak reactivity. In contrast, all five BCCs manifesting strong IMP3 positivity consisted of the indolent-growth histologic subtypes. BCCs with infiltrative histomorphology did not appear to have a tendency towards more striking production of IMP3. There was no significant relationship between the IMP3 expression status and the proliferation status (Ki-67 ≤ 50% vs. Ki-67 > 50%) of the tumor tissue (p > 0.05). Conclusions. The vast majority of cutaneous BCCs express IMP3, suggesting this oncoprotein is implicated in BCC carcinogenesis. However, more pronounced expression does not seem to be associated with aggressive-growth phenotype of BCC or higher proliferative activity of neoplastic cells.