Effects of Histone Methyltransferase Inhibitors on the Survival, Apoptosis and Cell Cycle of Raji Cells

  Objective  To determine the effects of three histone methylase inhibitors UNC1999, DZNep and GSK343 on the survival, apoptosis and cell cycle of non-hodgkin's lymphoma Raji cells.

  Methods  PCR amplified 16 and 18 exons of enhancer of zeste homolog 2 (EZH2) gene were detected. The expression of EZH2 in normal adult lymphocytes and Raji cells was detected by Western blot. The Raji cells were treated by UNC1999, DZNep and GSK343, followed by CCK-8 assays analyzing cell survival, flow cytometry detecting cell apoptosis and cell cycle, and Western blot detecting the expressions of EZH2 and H3K27 me3.

  Results  The Sanger sequencing results showed that the Raji cells did not carry Y641 and A677 mutation sites of EZH2. The Western blot results showed high expressions of EZH2 in the Raji cells. The results of CCK-8 showed that UNC1999, DZNep and GSK343 inhibited cell survival, and the weakest effect was from DZNep. The flow cytometric assay showed that UNC1999, DZNep and GSK343 promoted apoptosis of the Raji cells, and the effect of UNC1999 was stronger than that of GSK343 and DZNep. The cell cycle was arrested at phase G₁/G₀ after treatment of the Raji cells with the three inhibitors, with UNC1999 triggering the most significant changes. The Western blot showed that UNC1999 and GSK343 inhibited the histone methylase activity of EZH2 and significantly reduced the expression of H3K27 me3.

  Conclusion  EZH2 inhibitors can inhibit cell survival, promote cell apoptosis and arrest cell cycle at phase G₁/G₀ of Raji cells through reducing the expression of H3K27me3. UNC1999 has a stronger effect than GSK343 and DZNep.