CDH22 expression is reduced in metastatic melanoma.

Cadherin-like protein 22 (CDH22) is a transmembrane glycoprotein implicated in cell-cell adhesion and cancer metastasis. The expression of CDH22 has been shown to be increased in colorectal cancers. However, the role of CDH22 in melanomagenesis is not known. To investigate the role of CDH22 in melanoma progression, we examined the expression of CDH22 in melanocytic lesions at different stages and analysed the correlation between CDH22 expression and clinicopathlogic parameters and patient survival. Using tissue microarray and immunohisto-chemistry, we evaluated CDH22 staining in 76 dysplastic nevi, 247 primary melanomas, and 143 metastatic melanomas. We found that metastatic melanomas had a significantly higher percentage of negative CDH22 staining than dysplastic nevi (P = 0.012) and primary melanomas (P = 0.038). CDH22 expression was also reduced in thick (≥2 mm) and ulcerative melanomas (P = 0.003 and 0.022, respectively). Melanomas of AJCC stage II, III, and IV had a higher percentage of negative CDH22 staining than AJCC stage I melanomas (P = 0.004, P < 0.0001, and P = 0.009, respectively). Melanomas with negative CDH22 expression had significantly poorer disease-specific 5-year survival than those with positive CDH22 staining. Additionally, CDH22 expression depended on AJCC stage to predict patient survival. These data indicate that reduced CDH22 expression is associated with melanoma metastasis and poor patient prognosis.