Mechanistically, EZH2 specifically stabilizes the chromatin accessibility of a cluster of genes that are important for T<sub>FH</sub> fate commitment, particularly B cell lymphoma 6 (Bcl6), and thus directs T<sub>FH</sub> cell commitment.
The effects of ribavirin on the viability and clonogenicity of the B‑cell lymphoma cell line Pfeiffer (EZH2‑mutant), Toledo (EZH2 wild‑type) and cutaneous T‑cell lymphoma Hut78 cell line were assessed.
These drugs include immunomodulating agents such as lenalidomide, small-molecule inhibitors of the B-cell receptor signaling pathway such as ibrutinib and idelalisib, B-cell lymphoma 2 homology 3 mimetics such as venetoclax, and enhancer of zeste homolog 2 inhibitors such as tazemetostat.
We studied EZH2 expression in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), classic Hodgkin lymphoma (cHL), T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL), and B-cell Lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphomas and classic Hodgkin lymphoma (BCLu-DLBCL/cHL), as well as the coexpression of p-ERK, MYC, and p-STAT3 in these neoplasms.
A subset of B-cell lymphoma patients have dominant mutations in the histone H3 lysine 27 (H3K27) methyltransferase EZH2, which change it from a monomethylase to a trimethylase.
These emerging data suggest that EZH2 inhibitors represent a very promising class of drugs, which will probably have a major impact on improving outcome and reducing toxicity for patients with indolent and aggressive B-cell lymphomas and other specific solid tumors.
We discuss our current understanding of EZH2 somatic mutations frequently found in B-cell lymphomas and recurrent mutations in various other epigenetic regulators as novel molecular predictors and determinants of PRC2 sensitivity.
Immunoblot of DLBCL cell lines and microarray gene expression study of EZH2 in B-cell lymphomas were consistent with the immunohistochemistry findings.
These findings represent a novel promising approach for silencing MYC-miRNA-EZH2 amplification loop for combinatorial therapy of aggressive B-cell lymphomas.
The Ki67 labeling index showed a positive correlation with Ezh2 expression in B cell lymphomas (correlation coefficient (Co) = 0.983, P = 0.000) and T/NK cell lymphomas (Co = 0.629, P = 0.000).
We were also able to link these distinct microRNA profiles with cellular phenotypes, importantly showing that, in subset 1, miR-101 downregulation is associated with overexpression of the enhancer of zeste homolog 2 (EZH2) protein, which has been associated with clinical aggressiveness in other B-cell lymphomas.