TGF-beta in uveal melanoma

Uveal melanoma is the most common primary ocular cancer among adults and pa tients with distant metastases seldom survive longer than a year. Melanomas of the eye have the advantage of growing in the special environment of an immune privileged site and it has long been shown, that the special immunos uppressive properties of the intraocular microenvironment are strongly medi ated by cytokines, especially transforming growth factor-beta (TGF-beta). H ere, we sought to investigate the presence of TGF-beta in surgically remove d uveal melanoma specimens using immunohistochemical methods to verify poss ible autocrine mechanisms. Immunocytochemistry for pan-TGF-beta and TGF-bet a (2) was performed on 13 melanoma specimens using an alkaline phosphatase labeling procedure. Melanocytic origin of the tumors was confirmed by HMB-4 5 staining. All tissue samples exhibited positive staining using either pan -TGF-beta or TGF-beta (2) antibody regardless of cell-type, size of the tum or, or tumor location. The intensity of staining did not vary significantly within a given tumor. All tumors stained positive against the HMB-45 antib ody. Many cytokines have been found to act on melanoma tumors. The presence of the TGF-beta (2) isoform in all specimens points to progressive tumor-g rowth as has been shown for melanomas of the skin. Based on our immunohisto chemical findings and the immunosuppressive properties of TGF-beta, we supp ose that ocular melanomas should be able to create their own immunosuppress ive environment even in the uvea, which might be a non-privileged site. Mic rosc. Res. Tech. 52:396-400, 2001. (C) 2001 Wiley-Liss. Inc.