Purpose: Conjunctival melanoma (CM) is a rare disease associated with considerable mortality. As opposed to cutaneous melanoma, the epigenetic mechanisms involved in the development of CM and other mucosal melanomas (MMs) are unclear. The purpose of this study was to identify tumor-specific and prognostic microRNA (miRNA) in CM and to compare the miRNA profile with that of MM.
Methods: Using microarray analysis (Affymetrix) we determined the miRNA expression profile in 40 CMs compared with 7 normal conjunctival samples. Changes in miRNA expression were associated with T stage, local recurrence, metastasis, and mortality. Furthermore, the expression of six fresh frozen tissue samples of CM was compared with that of four laryngeal and sinonasal MM.
Results: Our analysis revealed 24 upregulated and 1 downregulated miRNA in CM; several of these miRNAs have key functions in the pathogenesis and progression of cutaneous melanoma. Additionally, we identified seven upregulated miRNAs specific for stage-T1 and stage-T2 CM, whose expression was associated with increased tumor thickness (P = 0.007), and two upregulated miRNAs (miR-3687 and miR-3916) associated with an increased risk of local recurrence. No stage T3-specific miRNAs were identified.
Conclusions: We identified differentially expressed and potentially prognostic miRNAs in CM. Furthermore, the miRNA expression pattern of CM resembled that in MM. The identification of these differentially expressed miRNAs provides an entry point for future functional studies of miRNAs as prognostic or therapeutic targets in CM and highlights the resemblance between CM, MM, and cutaneous melanoma.