ATRA-mediated Histone Modification Regulates PIM-1 Inhibition Of Proliferation And Differentiation Of HL-60 Cells

Acute Promyelocytic Leukemia(APL),a subtype of acute myeloid leukemia(AML),is characterized by myeloid cell differentiation arrested in the promyelocytic stage.The chromosomal translocation produces the fusion protein PML/RARA which is an important genetic feature of acute promyelocytic leukemia.Therefore,all-trans retinoic acid(ATRA)can be used as a clinical drug for the treatment of APL by targeting retinoic acid receptor alpha(RARα),which binds to the oncoprotein PML/RARA,and degrade the fusion protein PML/RARA to achieve therapeutic effects.There are a variety of epigenetic modification changes in the process of ATRA degradation of the PML/RARA protein,in which H3K27me3 induced gene silencing plays a most critical role,but the specific mechanism of this process is not clear.In order to elucidate the epigenetic mechanism of ATRA targeting in the promyelocytic leukemia,we first used promyelocytic leukemia cell line HL-60 as a model to treat cells with different concentrations of ATRA,and found that 1μM ATRA can effectively inhibit PML/RARA expression.Additionally,the cell proliferation ability decreased.At the same time,the flow cytometry results showed that the proportion of CD38~+cells increased significantly.These results indicate that ATRA promotes differentiation of HL-60 cells and induces apoptosis.On this basis,RNA-seq sequencing technology,ChIP-PCR was used to explore and identify the differentially expressed genes and the modification of H3K27me3 target gene locus of ATRA-treated cells.The results showed that the level of H3K27me3 methylation in the PIM-1 gene promoter region was significantly increased in ATRA-treated cells,indicating that ATRA may mediate the H3K27me3 methylation modification level to regulate the expression of PIM-1,resulting in the inhibition of cell proliferation,induction of cell differentiation.In conclusion,this experiment provides theoretical evidence for improving the mechanism of ATRA epigenetic modification of ATRA,and suggests that H3k27me3 modified PIM-1 may be a new target for the treatment of cancer.