TUMOR PROGRESSION AND METASTATIC BEHAVIOR IN-VIVO CORRELATES WITH INTEGRIN EXPRESSION ON MELANOCYTIC TUMORS

In order to evaluate the significance of adhesion molecules expressed on melanocytic tumours for progression and prognosis in vivo, we studi ed integrin expression (VLA-1 to VLA-6, CD18, CD51, CD61) on 10 naevi, 40 primary malignant melanomas, and 11 metastases by immunohistology using the APAAP technique. Evaluation was done by grouping the percent age of positive tumour cells in six categories. Statistical analysis ( Wilcoxon rank test, Scheffe test) revealed significant differences in the expression of VLA-1 (P<0.0001), VLA-2 (P=0.0001), VLA-5 (P=0.0093) , VLA-6 (P=0.0232), and CD61 (P=0.0002) between naevi and primary mela nomas. Comparing primary melanomas with metastases, a statistically si gnificant decrease in the expression of VLA-1, VLA-2, and VLA-6 was de tectable, as well as a significant increase in VLA-4 and VLA-5. There was no correlation between integrin expression and tumour type (superf icial spreading melanoma, nodular melanoma, lentigo maligna melanoma), regression and ulceration. Changes of VLA-1, VLA-4, and VLA-6 express ion correlated with the tumour thickness of the primary melanoma, but only VLA-4 and VLA-6 expression on primary melanomas correlated signif icantly with the development of metastases (P=0.024 and P=0.001). Thes e changes of integrin expression during tumour progression particularl y, the data showing an increase of VLA-4, and a decrease of VLA-6 expr ession support the concept that integrins are a new additional set of prognostic markers which indicate predisposition to the development of metastases.