To study the effect of tazemetostat on the stemness of diffuse large B-cell lymphoma and the related mechanism of action.

OCI-LY3 cells were divided into blank group, tazemetostat group and microRNA-378a-3p (miR-378a-3p) mimics group. Blank group cell conventional culture; tazemetostat group was treated with 5 μmol·L^-1 tazemetostat; miR-378a-3p mimics group was transfected with miR-378a-3p mimics. The relative expression level of miR-378a-3p was detected by fluorescence in situ hybridization. mRNA expression levels of dryness related factors were detected by quantitative real time polymerase chain reaction; the expression of signal pathway-related proteins was detected by Western blot.

The relative expression levels of miR-378a-3p in blank group and tazemetostat group were 1.00±0.14 and 0.52±0.08, respectively, the difference was statistically significant (P<0.001). The relative expression of octamer binding transcription factor 4 mRNA in blank group, tazemetostat group and miR-378a-3p mimics group were 1.00±0.16, 0.21±0.06 and 0.49±0.08, respectively; the relative expression of sex determining region Y box protein 2 mRNA were 1.00±0.09, 0.39±0.05 and 0.85±0.11, respectively; the relative expression of Nanog homeobox mRNA were 1.00±0.13, 0.17±0.03 and 0.65±0.10, respectively; the relative expressions of Kruppel like factor 4 mRNA were 1.00±0.10, 0.28±0.05 and 0.86±0.14, respectively; the relative expressions of Yes associated protein were 1.00±0.19, 3.46±0.52 and 2.14±0.36, respectively; the relative expression of transcriptional coactivator with PDZ-binding motif protein were 1.00±0.14, 1.90±0.35 and 1.51±0.33, respectively. The above indexes of tazemetostat group were compared with those of blank group, and the above indexes of miR-378a-3p mimics group were compared with those of tazemetostat group, the differences were statistically significant (P<0.001, P<0.05).

Tazemetostat can inhibit the stemness of OCI-LY3 cells by down-regulating the level of miR-378a-3p, which may be achieved through the Yes associated protein/transcriptional coactivator with PDZ-binding motif signaling pathway.