Uveal
melanoma is a highly malignant tumor of
the eye and it is the most common primary
ocular cancer among adults. Uveal melanoma
has a different expression pattern of surface
markers compared to cutaneous melanoma.
Recently, we have described a strong expression
of melanocortin 1 receptor (MC1R), a melanoma
specific marker, in primary and metastatic
cutaneous melanomas. In the present study,
we have analyzed the expression of MC1R
in uveal melanomas and compared it with
other common markers used for diagnosis.
METHODS: Seventeen primary uveal melanomas
were immunolabeled with a panel of antibodies
that included S100, HMB-45, A103 and the
novel monoclonal antibody MP1-1C11, which
recognizes the extra cellular region of
MC1R. RESULTS: The results were evaluated
according to an arbitrary scale: -, +/-,
+, on the basis of the intensity of the
immune reactivity. The MC1R protein was
detected in 95 percent (17/18) of the tested
melanoma tissues, including a lever metastasis.
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HMB-45
stained 66 percent (8/12) of tested melanomas.
In addition, we found that the sensitivity
for S100 was lower in uveal than in cutaneuos
melanoma. S100 was detected only in 33 percent
(5/15) of the analyzed samples. The antibody
directed to MART-1 (A103) recognized 4 of
6 ocular melanoma tissues. We also demonstrated
that surface expression of MC1R is up regulated
in vitro by different cytokines such as,
IFN-?, TNF, and IL-10 which may be relevant
for antibody mediated immunotherapy. CONCLUSIONS:
MC1R protein is more frequently expressed
in uveal melanomas than the proteins recognized
by HMB-45 and S100 antibodies and might
therefore also be included as target for
the antibody panel used for diagnosis of
uveal melanocytic lesions.
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