JARID1B Protein Expression and Prognostic Implications in Uveal Melanoma

Abstract

It has been suggested recently that stem cell marker expression of jumonji AT-rich interactive domain 1B (JARID1B) is required for continuous tumor growth and maintenance in human cutaneous melanoma cells. The aim of this study is to determine whether JARID1B is also expressed in uveal melanoma (UM) and whether JARID1B marks an expanded cancer stem cell pool in poor prognosis UM. Based on the available data, this is the first time JARID1B expression in UM has been studied. A total of 121 consecutive patients diagnosed with UM and who underwent enucleation were included in the study. Immunohistochemical staining with JARID1B antibodies was performed and immunoreactivity was assessed. Correlations of JARID1B expression with established clinicopathological parameters and overall survival (OS) were evaluated in univariate and multivariate analyses. JARID1B positive expression, as defined by >0% staining, was present in 55% of UMs and invariably in ciliary body epithelium. The correlation between JARID1B negative expression and JARID1B expression >5% inside the tumor tissue and OS was borderline statistically significant based on LogRank test at 5% significance level (P = 0.06). There were significantly more JARID1B positive cells in tumors with extrascleral extension than in tumors with no or minimal intrascleral invasion (P < 0.01, Mann-Whitney test). This study demonstrates that JARID1B is expressed by UM cells. Despite that JARID1B was highly expressed in UM, a statistically significant association (P < 0.05) between JARID1B expression and OS could not be obtained. However, a P-value of 0.06 could suggest that high JARID1B expression is correlated with lower survival; thus, a follow up study with a greater patient sample is recommended. In addition, samples of tumors characterized by high invasiveness showed a higher JARID1B expression. Furthermore, this study substantiates the presence of progenitor cells in the ciliary body epithelium.