Cytoplasmic Expression of LMP1 and its Nuclear Translocation in Nasopharyngeal Carcinoma Correlates with Epithelial-mesenchymal Transition

Up to now, the prognostic significance of latent membrane protein 1 (LMP1) in nasopharyngeal carcinoma (NPC) tissues still remains controversial. This study aims to investigate aberrant localization of LMP1 and its relationship with epithelial-mesenchymal transition (EMT) in NPC samples by immunohistochemistry and immunofluorescence. Both cytoplasmic and nuclear LMP1 expressions were observed in NPC tissues. In some tissues, nuclear LMP1 was frequently observed at tumor invasive front and tumor buddings. Nuclear LMP1 expression was significantly associated with lymph node metastasis (P=0.031), local recurrence (P=0.002), lymphatic invasion (P= 0.004) and tumor budding (P=0.001). Furthermore, nuclear LMP1 showed significant correlations with EMT markers including E-cadherin (P=0.037), Vimentin (P < 0.001), N-cadherin (P=0.003), Snail (P=0.003) and Twist (P=0.002), but not significantly linked with Fibronectin (P=0.103) and Slug (P=0.503). According to cytoplasmic LMP1, it correlated strongly with lymphatic invasion (P=0.044), vascular invasion (P=0.003) and EMT proteins including E-cadherin (P=0.014), Vimentin (P=0.006), N-cadherin (P=0.003), Snail (P=0.008) and Slug (P=0.007), whereas not significantly associated with Fibronectin (P=0.221) and Twist (P=0.106). However, multivariate analysis showed that nuclear LMP1 (P=0.844) and cytoplasmic LMP1 (P=0.291) were not independent predictors for NPC. In conclusion, we demonstrate firstly that abnormal localization of LMP1 correlates with EMT properties and aggressiveness in NPC, respectively.