We have examined the expression of the
cellular apoptosis susceptibility protein, a nuclear transport factor that plays a role in apoptosis and cell proliferation, in benign and malignant melanocytic lesions. Tissue samples of 55
formalin-fixed,
paraffin-embedded
melanoma (primary n=32, metastatic n=23) and of 27 control cases (junctional dermal, compound, Spitz, Reed,
blue nevi, balloon-cell
nevus,
lentigo maligna) were analyzed by immunohistochemistry with anti-cellular apoptosis susceptibility
antibodies. The percentage of cellular apoptosis susceptibility-positive cells as well as the intensity on a four-point scale was evaluated. In normal skin, expression of cellular apoptosis susceptibility was primarily found in the basal cell layer of the epidermis. Benign melanocytic lesions that stained positive for cellular apoptosis susceptibility (13 of 27) showed a homogeneously distributed staining pattern with a mean of 5+/-12% cellular apoptosis susceptibility positive cells. Five out of 7
lentigo maligna melanoma, 11 out of 12 superficial spreading
melanoma and all acrolentiginous (n=7) and nodular (n=6)
melanoma showed immunoreactivity of medium (++) to high ( ) intensity. Vertical growth phases of primary cutaneous
melanoma stained stronger than horizontally growing cell clusters. All
metastases (n= 23) stained strongly positive, the staining pattern being inhomogeneous. Cellular apoptosis susceptibility detection in clinical stages according to UICC showed an increase from 43+/-34% cellular apoptosis susceptibility positive cells in stage I, to 53+/-26% in stage II, 68+/-24% in stage III and 72+/-24% in stage IV, respectively. Because the expression of cellular apoptosis susceptibility correlates predominantly with advanced stages of
melanoma, staining with anti-cellular apoptosis susceptibility
antibodies may be useful for diagnosis of
melanoma and possibly as an immunohistochemical prognostic factor in cutaneous melanocytic lesions.