Clinical trials and experimental
VARIATION IN EXPRESSION OF METALLOPROTEINASES IN CUTANEOUS MELANOMA WITH REGRESSION, POSSIBLE INDICATOR OF TUMOR HETEROGENEITY

Spontaneous regression in melanoma is a relatively frequent phenomenon with unclear biologic and prognostic significance. Considering the importance of the epithelialmesenchymal transition (EMT) in tumor progression we analyzed immunohistochemical expression in melanoma of several EMT-involved: metalloproteinases (MMP).


We analyzed 93 melanomas (62 superficial spreading melanomas; 31 nodular melanoma), 39 of them presenting regression; we analyzed regressed component (RC) and nonregressed component (NRC) in melanoma with regression and the main tumor mass in melanoma without regression (AR). We compared the expression of each marker in NRC versus RC in the same tumor and in NRC versus AR.


MMP1 and MMP11 had diminished expression in NRC versus AR (P=0.047, P=0.029); there was a tendency towards reduced expression of MMP2, MMP3 and MMP13 in NRC versus AR; tendency towards diminished expression of MMP2, MMP3 and MMP11 in RC versus NRC was noted. Certain type of regression associated specific alterations in MMPs expression. Melanoma with segmental regression presented significant less expression of MMP1 than AR. We demonstrated different immunophenotype in RC and NRC areas, NRC being more similar to AR; more likely regression in melanoma is one phenotypical expression of intratumor heterogeneity, some forms of regression associating more favorable prognostic factors.