Abstract
Purpose:
Conjunctival melanoma is a rare malignant tumor, of which the biology remains largely unknown. Nestin, an intermediate filament protein described as neural stem cell marker, has been reported in cutaneous melanocytic tumors with potential implication for their diagnosis and staging. We analyzed the immunological properties of conjunctival melanomas and hypothesized that nestin could also have clinical interest as a biomarker in conjunctival melanomas.<br />
Methods:
Samples of tumoral tissue from five patients with a primary conjunctival melanoma and four cell lines (UKE29, UKE17, CR1 and CR2) derived from conjunctival melanoma were analyzed. Ten samples of limbal (n=5) or fornical (n=5) conjunctiva obtained from healthy subjects were used as controls. Expression of nestin and other pluripotency markers (Sox-2, Oct-4, Nanog, c-Myc, ABCG2, p63, and c-KIT) was examined using real-time polymerase chain reaction. Expression of nestin was additionally examined using immunohistochemical staining.
Results:
Expression of nestin was significantly higher in melanoma tissue than in controls (p<0.008 vs. limbal and p<0.02 vs. fornical conjunctiva), which was consistent with the results of immunological staining. The expression of other markers of pluripotency was not statistically different between melanomas and normal tissues from either limbal or fornical conjunctiva. In all cell lines the expression of nestin was inferior to the melanoma tissues. The expression of other markers of pluripotency was generally lower in cell lines compared to melanoma tissues, except for ABCG2 in UKE29 and p63 in UKE17. Compared to control tissues, nestin expression was higher in the cell line UKE17 than in limbal controls, and higher than both limbal and fornical controls in the cell line UKE29. The expression of other pluripotency markers was inferior in cell lines compared to all controls, apart from c-Myc in the cell line CR1 and ABCG2 in UKE 29.<br />
Conclusions:
Nestin is significantly overexpressed in conjunctival melanoma, whereas the expression shows a decrease in cell lines consistent with the general pattern of expression of other pluripotency markers in those cell lines. This observation supports the hypothesis that nestin can potentially serve as diagnostic adjunct in conjunctival melanoma.