Expression of cIAP-1 correlates with nodal metastasis in squamous cell carcinoma of the tongue

Cellular inhibitor-of-apoptosis protein 1 (cIAP-1) is a member of the inhibitor-of- apoptosis protein family, which predominantly regulates apoptosis. It has been suggested that expression of cIAP-1 correlates with certain clinicopathological features. The possible significance of cIAP-1 expression in cervical lymph node metastasis of tongue squamous cell carcinoma (SCC) is investigated. Seventy-five tongue SCCs were analyzed by immunohistochemistry. cIAP-1 immunoreactivity patterns were nuclear in 38 (51%), cytoplasmic in 47 (63%), and concurrent in 37 (49%) cases. Nuclear, cytoplasmic and concurrent cIAP-1 immunoreactions were significantly correlated with lymph node metastasis in tongue SCCs (P = 0.0011, 0.0012, and 0.0006, respectively). The cleaved caspase-3, which is a marker of tumor apoptosis, and Ki-67 index, which is a marker of tumor proliferation, were immunohistochemically examined in 21 tongue SCCs with concurrent nuclear and cytoplasmic cIAP-1 expression and with metastasis, and in 23 tongue SCCs without concurrent nuclear and cytoplasmic cIAP-1 expression and without metastasis. Concurrent cIAP-1 expression was inversely correlated with caspase-3 (P = 0.0066), but was positively correlated with Ki-67 expression (P = 0.0028). The mode of invasion was associated with lymph node metastasis (P = 0.014) and differentiation (P = 0.013), but was not correlated with cIAP-1 expression. There was no statistically significant correlation between nuclear or cytoplasmic cIAP-1 expression and the clinicopathological factors of gender, age, clinical stage or differentiation. These results suggest that both patterns of cIAP-1 are useful markers for predicting cervical lymph node metastasis in tongue SCC.