Securinine, a myeloid differentiation agent with therapeutic potential for AML

As the defining feature of Acute Myeloid Leukemia (AML) is a maturation arrest, a highly desirable therapeutic strategy is to induce leukemic cell maturation. This therapeutic strategy has the potential of avoiding the significant side effects that occur with the traditional AML therapeutics. We identified a natural compound securinine, as a leukemia differentiation-inducing agent. Securinine is a plant-derived alkaloid that has previously been used clinically as a therapeutic for primarily neurological related diseases. Securinine induces monocytic differentiation of a wide range of myeloid leukemia cell lines as well as primary leukemic patient samples. Securinine's clinical potential for AML can be seen from its ability to induce significant growth arrest in cell lines and patient samples as well as its activity in significantly impairing the growth of AML tumors in nude mice. In addition, securinine can synergize with currently employed agents such as ATRA and decitabine to induce differentiation. This study has revealed securinine induces differentiation through the activation of DNA damage signaling. Securinine is a promising new monocytic differentiation inducing agent for AML that has seen previous clinical use for non-related disorders.     

Knockdown of SALL4 Protein Enhances All-trans Retinoic Acid-induced Cellular Differentiation in Acute Myeloid Leukemia Cells

All-trans retinoic acid (ATRA) is a differentiation agent that revolutionized the treatment of acute promyelocytic leukemia. However, it has not been useful for other types of acute myeloid leukemia (AML). Here we explored the effect of SALL4, a stem cell factor, on ATRA-induced AML differentiation in both ATRA-sensitive and ATRA-resistant AML cells. Aberrant SALL4 expression has been found in nearly all human AML cases, whereas, in normal bone marrow and peripheral blood cells, its expression is only restricted to hematopoietic stem/progenitor cells. We reason that, in AMLs, SALL4 activation may prevent cell differentiation and/or protect self-renewal that is seen in normal hematopoietic stem/progenitor cells. Indeed, our studies show that ATRA-mediated myeloid differentiation can be largely blocked by exogenous expression of SALL4, whereas ATRA plus SALL4 knockdown causes significantly increased AML differentiation and cell death. Mechanistic studies indicate that SALL4 directly associates with retinoic acid receptor α and modulates ATRA target gene expression. SALL4 is shown to recruit lysine-specific histone demethylase 1 (LSD1) to target genes and alter the histone methylation status. Furthermore, coinhibition of LSD1 and SALL4 plus ATRA treatment exhibited the strongest anti-AML effect. These findings suggest that SALL4 plays an unfavorable role in ATRA-based regimes, highlighting an important aspect of leukemia therapy.     

The FLT3 inhibitor tandutinib (formerly MLN518) has sequence-independent synergistic effects with cytarabine and daunorubicin

AML remains a difficult disease to treat. Despite response to induction chemotherapy, most patients ultimately relapse. Further, among elderly patients, aggressive therapy options are often limited due to other medical conditions and decreased tolerance of these patients to conventional chemotherapy. Internal tandem duplications (ITD) of the FLT3 juxtamembrane domain occur in 20-30% of AML patients and predict poor outcome. First clinical data with the FLT3 inhibitor tandutinib demonstrated antileukemic activity in approximately half of the patients - predominantly with FLT3 ITD-positive AML. But the data also show that optimal use of tandutinib will require combination therapy with cytotoxic agents. Notably, single agent tandutinib has not been associated with myelosuppression, mucositis or cardiac toxicity - the dose limiting toxicities of AML chemotherapy. We determined the feasibility of combining tandutinib with the standard “3+7” induction regimen in AML and show that, in contrast to other structurally unrelated FLT3 inhibitors recently evaluated in clinical trials, the use of tandutinib displayed application sequence independent synergistic antileukemic effects in combination with cytarabine and daunorubicin. Strong synergistic antiproliferative and proapoptotic effects were thereby predominantly seen on FLT3 ITD-positive blasts. Further we demonstrate, that addition of tandutinib may allow dose reduction of chemotherapy without loss of overall antileukemic activity – but with a resultant decrease of potential side effects. This approach might be an interesting novel strategy especially in the treatment of elderly/comorbid patients. Our data provide a rationale for combining tandutinib with induction chemotherapy in intensified as well as in dose reduction protocols for FLT3 ITD-positive AML.     

The combination of DNA methyltransferase inhibitor therapy and immunotherapy for acute myeloid leukemia

Acute myeloid leukemia (AML), the most common form of acute leukemia in adults, is characterized by abnormal proliferation and blocked maturation and differentiation of myeloid precursor cells. AML is an aggressive cancer that progresses rapidly without treatment. Therefore, effective treatment modalities should be implemented immediately after diagnosis. The mainstay of classical AML therapy has been chemotherapy, which is not suitable for relapsing or refractory patients, especially elderly patients. Among emerging novel therapeutic approaches for AML, epigenetic therapy and immunotherapy represent two exciting therapeutic developments. This review focuses on discussion of the therapeutic considerations for AML from the perspective of combination treatment, which incorporates both DNA methyltransferase inhibitor therapy, as one of the most promising epigenetic therapies, and immune checkpoint inhibitor or dendritic cell-based vaccination treatments, as examples of immunotherapy. Both challenges and rationale in the optimization of therapeutic approaches, as well as recent clinical trial developments, along this line are summarized.     

Oncogenic RAS Enables DNA Damage- and p53-Dependent Differentiation of Acute Myeloid Leukemia Cells in Response to Chemotherapy

Acute myeloid leukemia (AML) is a clonal disease originating from myeloid progenitor cells with a heterogeneous genetic background. High-dose cytarabine is used as the standard consolidation chemotherapy. Oncogenic RAS mutations are frequently observed in AML, and are associated with beneficial response to cytarabine. Why AML-patients with oncogenic RAS benefit most from high-dose cytarabine post-remission therapy is not well understood. Here we used bone marrow cells expressing a conditional MLL-ENL-ER oncogene to investigate the interaction of oncogenic RAS and chemotherapeutic agents. We show that oncogenic RAS synergizes with cytotoxic agents such as cytarabine in activation of DNA damage checkpoints, resulting in a p53-dependent genetic program that reduces clonogenicity and increases myeloid differentiation. Our data can explain the beneficial effects observed for AML patients with oncogenic RAS treated with higher dosages of cytarabine and suggest that induction of p53-dependent differentiation, e.g. by interfering with Mdm2-mediated degradation, may be a rational approach to increase cure rate in response to chemotherapy. The data also support the notion that the therapeutic success of cytotoxic drugs may depend on their ability to promote the differentiation of tumor-initiating cells.     

CDK1 interacts with RARγ and plays an important role in treatment response of acute myeloid leukemia

Alterations in cell cycle pathways and retinoic acid signaling are implicated in leukemogenesis. However, little is known about the roles of cyclin-dependent kinases (CDKs) in treatment response of leukemia. In this study, we observed that CDK1 expression was significantly higher in bone marrow from 42 patients with acute myeloid leukemia (AML) at recurrence than that at first diagnosis (p = 0.04). AML patients had higher level of nuclear CDK1 in their leukemic blasts tended to have poorer clinical outcome compared with those with lower levels. We showed that CDK1 function is required for all-trans retinoic acid (ATRA) to achieve the optimal effect in U-937 human leukemic cells. CDK1 modulates the levels of P27^kip and AKT phosphorylation in response to ATRA treatment. Further, we show, for the first time, that RARγ in concert with ATRA regulates protein levels of CDK1 and its subcellular localization. The regulation of the subcellular content of CDK1 and RARγ by ATRA is an important process for achieving an effective response in treatment of leukemia. RARγ and CDK1 form a reciprocal regulatory circuit in the nucleus and influence the function and protein stability of each other and the level of P27^kip protein. In addition, expression of wee1 kinase and Cdc25A/C phosphatases also coincide with CDK1 expression and its subcellular localization in response to ATRA treatment. Our study reveals a novel mechanism by which CDK1 and RARγ coordinate with ATRA to influence cell cycle progression and cellular differentiation.     

Epigenetic Priming of AML Blasts for All-trans Retinoic Acid-Induced Differentiation by the HDAC Class-I Selective Inhibitor Entinostat

All-trans retinoic acid (ATRA) has only limited single agent activity in AML without the PML-RARα fusion (non-M3 AML). In search of a sensitizing strategy to overcome this relative ATRA resistance, we investigated the potency of the HDAC class-I selective inhibitor entinostat in AML cell lines Kasumi-1 and HL-60 and primary AML blasts. Entinostat alone induced robust differentiation of both cell lines, which was enhanced by the combination with ATRA. This “priming” effect on ATRA-induced differentiation was at least equivalent to that achieved with the DNA hypomethylating agent decitabine, and could overall be recapitulated in primary AML blasts treated ex vivo. Moreover, entinostat treatment established the activating chromatin marks acH3, acH3K9, acH4 and H3K4me3 at the promoter of the RARβ2 gene, an essential mediator of retinoic acid (RA) signaling in different solid tumor models. Similarly, RARβ2 promoter hypermethylation (which in primary blasts from 90 AML/MDS patients was surprisingly infrequent) could be partially reversed by decitabine in the two cell lines. Re-induction of the epigenetically silenced RARβ2 gene was achieved only when entinostat or decitabine were given prior to ATRA treatment. Thus in this model, reactivation of RARβ2 was not necessarily required for the differentiation effect, and pharmacological RARβ2 promoter demethylation may be a bystander phenomenon rather than an essential prerequisite for the cellular effects of decitabine when combined with ATRA. In conclusion, as a “priming” agent for non-M3 AML blasts to the differentiation-inducing effects of ATRA, entinostat is at least as active as decitabine, and both act in part independently from RARβ2. Further investigation of this treatment combination in non-M3 AML patients is therefore warranted, independently of RARβ2 gene silencing by DNA methylation.     

ATRA-induced upregulation of Beclin 1 prolongs the life span of differentiated acute promyelocytic leukemia cells

Acute promyelocytic leukemia (APL) results from a blockade of granulocyte differentiation at the promyelocytic stage. All-trans retinoic acid (ATRA) induces clinical remission in APL patients by enhancing the rapid differentiation of APL cells and the clearance of PML-RARα, APL's hallmark oncoprotein. In the present study, we demonstrated that both autophagy and Beclin 1, an autophagic protein, are upregulated during the course of ATRA-induced neutrophil/granulocyte differentiation of an APL-derived cell line named NB4 cells. This induction of autophagy is associated with downregulation of Bcl-2 and inhibition of mTOR activity. Small interfering RNA-mediated knockdown of BECN1 expression enhances apoptosis triggered by ATRA in NB4 cells but does not affect the differentiation process. These results provide evidence that the upregulation of Beclin 1 by ATRA constitutes an anti-apoptotic signal for maintaining the viability of mature APL cells, but has no crucial effect on the granulocytic differentiation. This finding may help to elucidate the mechanisms involved in ATRA resistance of APL patients, and in the ATRA syndrome caused by an accumulation of mature APL cells.     

预激方案HAG及CAG治疗老年初治急性髓性白血病的对比研究

目的:评价含粒细胞集落刺激因子(granulocyte colony-stimulating-factor,G-CSF)的预激HAG及CAG方案治疗老年初治急性髓性白血病(AML)的疗效及不良反应,并对两个方案的疗效及不良反应进行比较。方法:65例老年初治AML分为HAG预激治疗组及CAG预激方案治疗组,31例患者予以HAG预激方案治疗,34例患者予以预激方案CAG方案治疗,所有患者在第1疗程后间歇14d左右进行第2个疗程。结果:HAG预激方案治疗组的完全缓解率为74.2%,总有效率为83.8%;CAG预激治疗组完全缓解(CR)率为67.6%,总有效率达为82.4%。两治疗组的血液系统不良反应及非血液系统毒性不良反应比较无显著性差异。结论:HAG预激方案化疗强度温和、敏感性好、CR率及有效率高、毒副作用小;与CAG预激治疗比较,HAG预激方案可以取的相似的疗效及较少的不良反应,在老年初治AML患者值得推荐应用。     

ATRA-induced upregulation of Beclin 1 prolongs the life span of differentiated acute promyelocytic leukemia cells

Acute promyelocytic leukemia (APL) results from a blockade of granulocyte differentiation at the promyelocytic stage. All-trans retinoic acid (ATRA) induces clinical remission in APL patients by enhancing the rapid differentiation of APL cells and the clearance of PML-RARα, APL’s hallmark oncoprotein. In the present study, we demonstrated that both autophagy and Beclin 1, an autophagic protein, are upregulated during the course of ATRA-induced neutrophil/granulocyte differentiation of an APL-derived cell line named NB4 cells. This induction of autophagy is associated with downregulation of Bcl-2 and inhibition of mTOR activity. Small interfering RNA-mediated knockdown of BECN1 expression enhances apoptosis triggered by ATRA in NB4 cells but does not affect the differentiation process. These results provide evidence that the upregulation of Beclin 1 by ATRA constitutes an anti-apoptotic signal for maintaining the viability of mature APL cells, but has no crucial effect on the granulocytic differentiation. This finding may help to elucidate the mechanisms involved in ATRA resistance of APL patients, and in the ATRA syndrome caused by an accumulation of mature APL cells.     

Programmed cell death-4 tumor suppressor protein contributes to retinoic acid-induced terminal granulocytic differentiation of human myeloid leukemia cells

Programmed cell death-4 (PDCD4) is a recently discovered tumor suppressor protein that inhibits protein synthesis by suppression of translation initiation. We investigated the role and the regulation of PDCD4 in the terminal differentiation of acute myeloid leukemia (AML) cells. Expression of PDCD4 was markedly up-regulated during all-trans retinoic acid (ATRA)-induced granulocytic differentiation in NB4 and HL60 AML cell lines and in primary human promyelocytic leukemia (AML-M3) and CD34(+) hematopoietic progenitor cells but not in differentiation-resistant NB4.R1 and HL60R cells. Induction of PDCD4 expression was associated with nuclear translocation of PDCD4 in NB4 cells undergoing granulocytic differentiation but not in NB4.R1 cells. Other granulocytic differentiation inducers such as DMSO and arsenic trioxide also induced PDCD4 expression in NB4 cells. In contrast, PDCD4 was not up-regulated during monocytic/macrophagic differentiation induced by 1,25-dihydroxyvitamin D3 or 12-O-tetradecanoyl-phorbol-13-acetate in NB4 cells or by ATRA in THP1 myelomonoblastic cells. Knockdown of PDCD4 by RNA interference (siRNA) inhibited ATRA-induced granulocytic differentiation and reduced expression of key proteins known to be regulated by ATRA, including p27(Kip1) and DAP5/p97, and induced c-myc and Wilms' tumor 1, but did not alter expression of c-jun, p21(Waf1/Cip1), and tissue transglutaminase (TG2). Phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway was found to regulate PDCD4 expression because inhibition of PI3K by LY294002 and wortmannin or of mTOR by rapamycin induced PDCD4 protein and mRNA expression. In conclusion, our data suggest that PDCD4 expression contributes to ATRA-induced granulocytic but not monocytic/macrophagic differentiation. The PI3K/Akt/mTOR pathway constitutively represses PDCD4 expression in AML, and ATRA induces PDCD4 through inhibition of this pathway.     

PML-RARA-targeted DNA vaccine induces protective immunity in a mouse model of leukemia

Despite improved molecular characterization of malignancies and development of targeted therapies, acute leukemia is not curable and few patients survive more than 10 years after diagnosis. Recently, combinations of different therapeutic strategies (based on mechanisms of apoptosis, differentiation and cytotoxicity) have significantly increased survival. To further improve outcome, we studied the potential efficacy of boosting the patient's immune response using specific immunotherapy. In an animal model of acute promyelocytic leukemia, we developed a DNA-based vaccine by fusing the human promyelocytic leukemia-retinoic acid receptor-alpha (PML-RARA) oncogene to tetanus fragment C (FrC) sequences. We show for the first time that a DNA vaccine specifically targeted to an oncoprotein can have a pronounced effect on survival, both alone and when combined with all-trans retinoic acid (ATRA). The survival advantage is concomitant with time-dependent antibody production and an increase in interferon-gamma (IFN-gamma). We also show that ATRA therapy on its own triggers an immune response in this model. When DNA vaccination and conventional ATRA therapy are combined, they induce protective immune responses against leukemia progression in mice and may provide a new approach to improve clinical outcome in human leukemia.     

JWA, a novel signaling molecule, involved in the induction of differentiation of human myeloid leukemia cells

Dysregulation of hematopoietic cellular differentiation contributes to leukemogenesis. Unfortunately, relatively little is known about how cell differentiation is regulated. JWA (AF070523) is a novel all-trans retinoic acid (ATRA) responsible gene that initially isolated from ATRA-treated primary human tracheal bronchial epithelial cells. For the notable performance achieved by ATRA in the differentiation induction therapy, we investigated the role of JWA in the induction of differentiation of human myeloid leukemia cells. Our results showed that JWA was not only regulated by ATRA but also by several other differentiation inducers such as phorbol-12-myristate-13-acetate (TPA), arabinoside (Ara-C), and hemin, involved in the mechanisms of differentiation along different lineages of myeloid leukemia cells arrested at different stages of development. Generally, JWA was up-regulated by these inducers in a time-dependent manner. Inhibition of JWA by RNA interference decreased the induced cellular differentiation. However, in NB4 cells treated with ATRA, dissimilar with others, the expression of JWA was down-regulated, and the induced cellular differentiation could be enhanced by silencing of JWA. Collectively, JWA works as a potential critical molecule, associated with multi-directional differentiation of human myeloid leukemia cells. In NB4 cells, JWA may function as a lineage-restricted gene during differentiation along the monocyte/macrophage-like or granulocytic pathway.     

Celastrol Inhibits Lung Infiltration in Differential Syndrome Animal Models by Reducing TNF-α and ICAM-1 Levels while Preserving Differentiation in ATRA-Induced Acute Promyelocytic Leukemia Cells

All-trans retinoic acid (ATRA) is a revolutionary agent for acute promyelocytic leukemia (APL) treatment via differentiation induction. However, ATRA treatment also increases cytokine, chemokine, and adhesive molecule (mainly ICAM-1) expression, which can cause clinical complications, including a severe situation known as differentiation syndrome (DS) which can cause death. Therefore, it is of clinical significance to find a strategy to specifically blunt inflammatory effects while preserving differentiation. Here we report that the natural compound, celastrol, could effectively block lung infiltrations in DS animal models created by loading ATRA-induced APL cell line NB4. In ATRA-treated NB4 cells, celastrol could potently inhibit ICAM-1 elevation and partially reduce TNF-α and IL-1β secretion, though treatment showed no effects on IL-8 and MCP-1 levels. Celastrol’s effect on ICAM-1 in ATRA-treated NB4 was related to reducing MEK1/ERK1 activation. Strikingly and encouragingly, celastrol showed no obvious effects on ATRA-induced NB4 differentiation, as determined by morphology, enzymes, and surface markers. Our results show that celastrol is a promising and unique agent for managing the side effects of ATRA application on APL, and suggest that hyper-inflammatory ability is accompanied by, but not necessary for, APL differentiation. Thus we offered an encouraging novel strategy to further improve differentiation therapy.     

All-trans retinoic acid induces apoptosis in acute myeloblastic leukaemia cells

The effect of all-trans retinoic acid (ATRA) on leukaemia cell differentiation, proliferation and induction of apoptosis was studied by using autonomously growing blast cells isolated from eight patients with acute myeloblastic leukaemia (AML) either at diagnosis ( n=4) or at relapse (n=4). No morphological or functional differentiation induced by ATRA was observed in any of the cases studied. In cell cultures, inhibition of leukaemia cell growth by ATRA was obvious, especially in the case of clonogenic cells, and it was both time- and concentration-dependent. Induction of apoptosis was more difficult to achieve. The cells retained over 90% viability in suspension when the ATRA exposure at any of the concentrations studied was 48 h or less. When the time of exposure to ATRA was longer than 48 h, the viability of the cells decreased in a concentration-dependent manner. Apoptosis was observed morphologically in each of the AML cases with 10-5 to 10-8 M ATRA, if the incubation time of cells in ATRA was 72 h. The percentage of apoptotic cells increased with increasing ATRA concentrations from 12± 9% of 10-8 M ATRA to 78±12% of 10-5 M ATRA. The DNA electrophoretic method was able to detect apoptosis in all the AML samples exposed to 10-7 and 10-6 ATRA for 48 h and occasionally in cases where lower concentrations and longer exposure time were used. In conclusion, the present study shows that it is possible to induce apoptotic leukaemia cell death in vitro with ATRA in AML, and this effect is dependent on both concentration and exposure time.     

EGFR inhibitors exacerbate differentiation and cell cycle arrest induced by retinoic acid and vitamin D3 in acute myeloid leukemia cells

By means of an unbiased, automated fluorescence microscopy-based screen, we identified the epidermal growth factor receptor (EGFR) inhibitors erlotinib and gefitinib as potent enhancers of the differentiation of HL-60 acute myeloid leukemia (AML) cells exposed to suboptimal concentrations of vitamin A (all-trans retinoic acid, ATRA) or vitamin D (1α,25-hydroxycholecalciferol, VD). Erlotinib and gefitinib alone did not promote differentiation, yet stimulated the acquisition of morphological and biochemical maturation markers (including the expression of CD11b and CD14 as well as increased NADPH oxidase activity) when combined with either ATRA or VD. Moreover, the combination of erlotinib and ATRA or VD synergistically induced all the processes that are normally linked to terminal hematopoietic differentiation, namely, a delayed proliferation arrest in the G₀/G₁ phase of the cell cycle, cellular senescence, and apoptosis. Erlotinib potently inhibited the (auto)phosphorylation of mitogen-activated protein kinase 14 (MAPK14, best known as p38^MAPK) and SRC family kinases (SFKs). If combined with the administration of ATRA or VD, the inhibition of p38^MAPK or SFKs with specific pharmacological agents mimicked the pro-differentiation activity of erlotinib. These data were obtained with 2 distinct AML cell lines (HL-60 and MOLM-13 cells) and could be confirmed on primary leukemic blasts isolated from the circulation of AML patients. Altogether, these findings point to a new regimen for the treatment of AML, in which naturally occurring pro-differentiation agents (ATRA or VD) may be combined with EGFR inhibitors.     

Over-expression of Mcl-1 impairs the ability of ATRA to induce growth arrest and differentiation in acute promyelocytic leukemia cells

Exposure of acute promyelocytic leukemia (APL) cells to all-trans retinoic acid (ATRA) increases levels of Mcl-1, however, the implication of ATRA-mediated expressions of Mcl-1 in these cells remains to be fully elucidated. This study found that exposure of NB4 and PL-21 cells to ATRA increased levels of Mcl-1 in association with phosphorylation of c-jun N-terminus kinases. Down-regulation of Mcl-1 by a small interfering (siRNA) or an inhibitor of JNK significantly potentiated the ability of ATRA to induce differentiation and apoptosis in these cells. On the other hand, the anti-leukemia effects of ATRA were blunted when Mcl-1 was forced expressed in NB4 and PL-21 cells as well as leukemia cells isolated from individuals with APL. Furthermore, down-regulation of Mcl-1 by an siRNA sensitized non-APL U937 and KG-1 leukemia cells to ATRA-mediated differentiation and apoptosis. Taken together, inhibition of Mcl-1 might be useful to potentiate the action of ATRA in APL as well as non-APL AML cells.     

Acute myeloid leukemia: treatment over 60

Undertreatment of older patients with acute myeloid leukemia (AML) can explain, in part, their inferior outcome when compared to that of younger patients. In agreement with the benefit seen by patients under age 60 from high-dose cytosine arabinoside (Ara-C), there are dose effects in the over 60s, in particular for daunorubicin, in induction treatment and for the duration of postremission treatment. The use of these effects can partly overcome the mostly unfavorable disease biology in older age AML, as expressed by the absence of favorable and the over-representation of adverse chromosomal abnormalities as well as the expression of drug resistance. We recommend an adequate dosage of 60 mg/m2 daunorubicin on 3 days in combination with standard dose Ara-C and 6-thioguanine given for induction and consolidation, and followed by a prolonged monthly maintenance chemotherapy for at least 1 year's duration. Further improvements in supportive care may help to deliver additional antileukemic cytotoxicity. As a novel approach, nonmyeloablative preparative regimens may open up the possibility of allogeneic transplantation for older patients with AML. Other new options like multidrug resistance modulators, antibody targeted therapies and molecular targeting are under clinical investigation. A questionnaire study in patients with AML showed that, according to patients' self-assessment, intensive and prolonged treatment did not result in a diminished quality of life. This finding did not vary by age, under or over 60 years. As the median age in this disease is more than 60 years, the adequate management of AML in older patients remains the major challenge.     

急性白血病基因突变与多步骤发病机制和临床相关性

急性髓细胞白血病(AML)是一组在发病机制和临床行为方面差异较大的疾病.在急性早幼粒细胞白血病中(APL),PML-RARα是APL的关键驱动(driver)突变,具有显性负的调控作用,影响髓系分化、凋亡和DNA复制和修复,其特殊结构使其成为全反式维甲酸和三氧化二砷的靶标.随着第二代测序技术的发展,在AML中发现了一些新的基因突变,其中DNA甲基转移酶3A(DNMT3A)突变是与表观遗传学相关的、与AML较差预后有关的基因事件.在1185例AML的基因分析中,研究发现与表观遗传学相关的第Ⅲ类突变与老年、高WBC及较差的临床预后有关.AML的发病是多步骤的,涉及不同通路上不同分子事件的相互作用,目前认为影响转录因子和信号传导通路的分子事件相互作用是AML完全发病的重要模式之一.