Differential expression of nm23 H-1 protein in conjunctival melanoma and potential precursor lesions

Loss of nm23 gene expression is believed to enhance metastatic spread in di verse human tumors, including skin melanoma. The purpose of this work was t o determine the pattern and prognostic relevance of nm23 protein immunoexpr ession in conjunctival melanoma and potential precursor lesion. Formaldehyd e-fixed, paraffin-embedded conjunctival specimens comprising 85 melanocytic lesions (nevi, primary aquired melanosis with and without atypia and prima ry and locally recurrent malignant melanomas) from 73 patients were used. S ections from all specimens were examined by light microscopy to assess dive rse prognostic parameters. Additional sections were then immunostained for nm23 H-l protein and the immunoreactivity was assessed semi-quantitatively. Survival data for all patients were retrieved from the National Causes of Death Registry of Sweden. Nm23 H-1 protein was differentially expressed in conjunctival melanocytic l esions, however loss of immunoexpression was not more common in melanocytic lesions associated with a high risk of malignant transformation. Also, pri mary and recurrent conjunctival melanomas showed an essentially similar nm2 3 expression pattern and we could not associate the pattern of nm23 immunoe xpression with an increased risk for malignant transformation or locally re current disease. While there was a tentative separation between cause-speci fic survival curves after excision for low and high nm23 expression conjunc tival melanoma, there was no statistically significant association with met astatic death of patients. However, loss of nm23 protein immunoexpression m ay still be of some importance as a marker for prognosis in conjunctival me lanoma because the present study could only detect large differences in sur vival. Our results suggest that any potential prognostic Value of nm23 immu noexpression would be independent of other markers, underlining the importa nce of further studies. (C) 1999 Academic Press.