Preliminary Mechanism Study of MYBL2 Gene in Acute Myeloid Leukemia Cells

Objective: To investigate the expression of MYBL2 gene in the human acute myeloid leukemia cell lines and explore its molecular mechanisms.

Methods: Western blot was used to detect the protein expression of MYBL2 in several leukemia cell lines. Lent virus was used to interfere expression of MYBL2 in NB4 and K562 cells, which had high expression of MYBL2. Si-MYBL2 group: the expression of MYBL2 in NB4 and K562 cells was inhibited by MYBL2 RNA interference lent virus. Si-NC group: NB4 and K562 cells were infected with negative control lent virus. Fluorescence microscope was used to observe themorphology of leukemia cells between interference group and the negative control group. Proliferation differences were detected by CCK8 analysis. Flow cytometry was performed to assess the cell cycle of leukemia cells. The nucleus by hoechst 33342 staining was observed in leukemia cells. We identified the expression of MYBL2 protein after RNA interference lent virus infection via western blot. Furthermore, the recognized cell cycle markers that C-MYC and PLK1, and the phosphorylation level of ERK was measured by western blot.

Results: MYBL2 protein was highly expressed in NB4, K562 and other leukemia cells. When MYBL2 gene was successfully interfered in leukemia cells, the cell volume of the experimental group was significantly increased compared with control group. CCK8 assay showed that cell proliferation decreased obviously after MYBL2 interference lent virus infected leukemia cells (P< 0.05), the difference was statistically significant compared with control group .Down regulation of MYBL2 in leukemia cells induced cell cycles arrest in G1 phase( P< 0.05) and prevented cell cycle progression. Hoechst 33342 staining showed that nucleus became larger and irregular in the MYBL2 RNA interference group. Western blot analysis shows that the expression of C-MYC and PLK1 in leukemia cells was inhibited, which was in accordance with MYBL2 protein expression, while the phosphorylation of ERK was significantly increased. Further studies should be conducted to explore the possible mechanism of MYBL2 in leukemia cells.

Conclusion: In vitro, MYBL2 gene plays an important role in the proliferation of leukemic cells and affects the cell cycle distribution; inhibiting MYBL2 gene induces cell cycle arrest in G1 phase and cell proliferation significantly decreased. MYBL2 gene can regulate cell cycle in leukemia cells with C-MYC and PLK1 genes. The MYBL2 gene may regulate cell cycle of leukemia cell through ERK cell signaling pathway.