The Clinical Significance And Pathogenesis Of HDOT1L Gene In Acute Leukemia Patients

Objective: The occurrence and development of leukemia is closely related with the abnormal epigenetic modifications. And it is the result of the cytogenetics and epigenetics changes. Studies have confirmed that the dysregulation of leukemia cell cycle progression and uncontrolled multiplication was associated with the cyclin expression or missing. The inhibition of apoptosis is closely connected with pro-apoptosis genes hypermethylation and apoptosis suppressor genes hypomethylation.The researchers found that the human DOT1 enzyme(h DOT1L) was a new class histone lysine methylation transferase,which could activate a set of genes and played a key role in the acute myeloid leukemia(AML) through prompting the H3K79 hypermethylation. By comparing the expressive levels of h DOT1 L gene and H3K79 methylation in newly diagnosed, remission stage and relapsed acute leukemic patients, our study explores the effects of h DOT1 L on the mechanism and clinical significance of acute leukemia. And we also detect the expressions of key moleculars in the both h DOT1 L signaling pathway and PI3K/AKT signal pathway. Moreover, we analyse the possible mechanism and the influence of development and prognosis of leukemia, in order to provide a new target for the treatment of leukemia, and research the new drug.Data: We collected the bone marrow specimens of acute myeloid leukemia(AML) patients, acute lymphoblastic leukemia(ALL) patients, acute leukemia relapse(AL- ralapse) patients and remission(AL- CR) patients, which came from the patients in the Second Hospital of Hebei Medical University in 2013-2014. The first experimental group was AML group, a total of 20 cases; the second experimental group was ALL group, a total of 20 cases; the third experimental group was AL-relapse group, a total of 22 cases, including AML-relapse for 12 cases and ALL-relapse 10 cases; and the fourth experimental group was AL-CR group, a total of 20 cases. All patients went through MICM that morphloogy(Morphology, M), immunology(Immunology, I), cytogenetics(Cytogenetics, C) and moleculargenetics(Moleculargenetics, M) diagnosis, conform the diagnostic criteria of 2008 WHO. 20 healthy volunteers as a control group, the experimental group of 82 cases, including 45 males and 37 females, age of 17-78 years, mean age 47.5 years; a total of 20 cases in the control group, 8 males and 12 females, age 23-68 years, mean age 45.5 years. All specimens extracted mononuclear cells, and saved-80 ℃refrigerator.Methods:1 Realtime-PCR method was used to detect the expression levels of intracellular HOXA9, HOXA10, MLL-AF10, and h DOT1 L m RNA..2 Expression levels of DOT1 L and H3K79-me2 were detected by Western Blot.3 Western Blot detected the expression levels of PI3 K, AKT, CDK4, Cyclin D1.4 Correlation analysis of cell cycle with h DOT1 L and PI3K/AKT signaling pathway, to explore the inner relationship between h DOT1 L signaling pathway and PI3K/AKT signaling pathway.5 Data were analysed by statistics.Results:1 Our results showed the h DOT1 L, HOXA9, HOXA10 and MLL-AF10 gene were expressed at the m RNA level in all cases. RT-PCR results indicated that expression levels of those genes in AML, ALL and AL-relapse group were higher than those in the control group and AL-CR group(P<0.01).These genes expression levels in AL-CR group were no significant difference compared with those in the control group(P > 0.05). And these genes expression levels in the other three groups were also no significant difference(P>0.05).2 Western blot results displayed that the expression levels of h DOT1 L, PI3 K, AKT and H3K79-me2 in AML group, ALL group, AL-relapse group were higher than those in the control group and AL-CR group(P<0.01). The expression levels of those molecules in the AL-CR group were no significant difference compared with those in the control group(P>0.05).And these proteins expression levels in the other three groups were no significant difference too(P>0.05).3 The expression levels of CDK4 and Cyclin D1 in AML group and ALL group were higher than those in the control group and AL-CR group(P<0.01). Compared with ALL group, the protein levels of CDK4 and Cyclin D1 in AML group were no significant differences(P>0.05). The expression levels of those molecules in the AL-CR group were no significant difference compared with those in the control group(P>0.05).Conclusions:1 h DOT1 L is a new type of histone lysine methylation transferase, which can improve the expression levels of H3K79 methylation and leukemia- promoting genes HOXA9, HOXA10, MLL- AF10. h DOT1 L pathway is involved in the pathogenesis and prognosis of acute leukemia.2 PI3K/AKT signaling pathway plays an important role in pathogenesis and prognosis in leukemia. The changes of four key moleculars PI3 K, and AKT, CDK4, Cyclin D1 expression are consistent with the changes of Hox A9, Hox A10, MLL-AF10 gene expression.There is a possible link between PI3K/AKT signaling pathway and h DOT1 L pathway. This is worth our further study.