LRIG-1 provides a novel prognostic predictor in squamous cell carcinoma of the skin: Immunohistochemical analysis for 38 cases

BACKGROUND. The LRIG-1 gene (formerly LIG-1) encodes a type 1 transmembrane glycoprotein with an extracellular region of 15 leucine-rich repeats and 3 immunoglobulin-like domains. LRIG-1 interacts with ErbB receptors, down-regulating the downstream signals. Because ErbB signaling is disrupted in cutaneous squamous cell carcinoma (SCC), we examined LRIG-1 expression in cutaneous SCC. OBJECTIVE. To analyze the differential expression of LRIG-1 and to investigate whether LRIG-1 is useful as a prognostic indicator in SCC of the skin. METHODS. LRIG-1 expression in 38 cases of cutaneous SCC patients was examined by immunohistochemistry. RESULTS. LRIG-1 expression was highest in well-differentiated lesions of cutaneous SCC. The cases studied here were categorized into 23 cases (60.5%) of high expression and 15 cases (39.5%) of low expression of LRIG-1. There was a significant correlation (p =.000018) of LRIG-1 expression intensity of tumor cells with histologic differentiation of SCC. Furthermore, we found a significant inverse correlation with metastatic rate (p =.02). When the overall survival of SCC patients was statistically compared between high and low LRIG-1 expression groups, a significant survival benefit for the patients in the former group was found (p =.03). CONCLUSION. LRIG-1 expression is an excellent candidate for a prognostic indicator of cutaneous SCC.