Enhancer of zeste homolog 2 is widely expressed in T-cell neoplasms, is associated with high proliferation rate and correlates with MYC and pSTAT3 expression in a subset of cases

Enhancer of zeste homolog 2 (EZH2), an epigenetic regulator and H3k27-specific histone methyltransferase, is important for transcriptional regulation. EZH2 has been found to be overexpressed in B-cell lymphomas, as well as some T-cell lymphomas. Here we investigated the expression of EZH2 by immunohistochemical staining in a wide range of T-cell neoplasms. We found that EZH2 is highly expressed in all categories of T-cell neoplasia studied, and its expression strongly correlates with a high proliferation rate. Although up-regulation of EZH2 has been reported to be modulated by the pSTAT3-MYC pathway, our data indicate that EZH2 expression is correlated with MYC and/or pSTAT3 expression in only a subset of T-cell lymphomas, and that other mechanisms may control the overexpression of EZH2 in many T-cell lymphomas. The high level of EZH2 expression in T cell lymphomas suggest that these neoplasms may benefit from targeted treatment with a small molecule inhibitor of EZH2 currently in use in clinical trials.