[Differential Analysis of Macular Structure and Microcirculation in Both Eyes of Patients With Myopic Anisometropia].

Objective To compare the macular structure and microcirculation in both eyes of the patients with myopic anisometropia.Methods Optical coherence tomography angiography(OCTA)was employed to scan the macular areas in both eyes of 44 patients with myopic anisometropia.The patients were assigned into high and low groups based on the refractive diopter,and the parameters such as retinal thickness,choroidal thickness,vascular density,and perfusion density in the macular areas of both eyes were compared between the two groups.Results Other macular areas except the central and external nasal areas and the choroid of the fovea in the high group were thinner than those in the low group(all P<0.05).There was no statistically significant difference in retinal vascular density or perfusion density in different areas between the two groups(all P>0.05).Conclusion In the patients with myopic anisometropia,most areas of the retina in the case of high myopia is thinner than that in the case of low myopia,while there is no difference in retinal vascular density or perfusion density in both eyes.

An AI-Aided Diagnostic Framework for Hematologic Neoplasms Based on Morphologic Features and Medical Expertise.

A morphologic examination is essential for the diagnosis of hematological diseases. However, its conventional manual operation is time-consuming and laborious. Herein, we attempt to establish an artificial intelligence (AI)-aided diagnostic framework integrating medical expertise. This framework acts as a virtual hematological morphologist (VHM) for diagnosing hematological neoplasms. Two datasets were established as follows: An image dataset was used to train the Faster Region-based Convolutional Neural Network to develop an image-based morphologic feature extraction model. A case dataset containing retrospective morphologic diagnostic data was used to train a support vector machine algorithm to develop a feature-based case identification model based on diagnostic criteria. Integrating these 2 models established a whole-process AI-aided diagnostic framework, namely, VHM, and a 2-stage strategy was applied to practice case diagnosis. The recall and precision of VHM in bone marrow cell classification were 94.65% and 93.95%, respectively. The balanced accuracy, sensitivity, and specificity of VHM were 97.16%, 99.09%, and 92%, respectively, in the differential diagnosis of normal and abnormal cases, and 99.23%, 97.96%, and 100%, respectively, in the precise diagnosis of chronic myelogenous leukemia in chronic phase. This work represents the first attempt, to our knowledge, to extract multimodal morphologic features and to integrate a feature-based case diagnosis model for designing a comprehensive AI-aided morphologic diagnostic framework. The performance of our knowledge-based framework was superior to that of the widely used end-to-end AI-based diagnostic framework in terms of testing accuracy (96.88% vs 68.75%) or generalization ability (97.11% vs 68.75%) in differentiating normal and abnormal cases. The remarkable advantage of VHM is that it follows the logic of clinical diagnostic procedures, making it a reliable and interpretable hematological diagnostic tool.

Spliceosome inhibitor induces human hematopoietic progenitor cell reprogramming toward stemness.

The application of hematopoietic stem cells (HSCs) has been restricted due to limited cell sources and conventional methods for generating these cells by cell expansion and pluripotent stem cell differentiation have not been clinically achieved. Cell reprogramming technique provides a new hope for generating desirable cells. We previously reported that mouse differentiated hematopoietic cell reprogramming could be induced by small molecule compounds to generate hematopoietic stem/progenitor-like cells, whether the human hematopoietic cells could also be reprogrammed into HSCs by chemical compounds remains elusive. Here, we demonstrated for the first time that human committed hematopoietic progenitors could be reprogrammed into multipotent progenitors by spliceosome inhibitor. Combination of single cell RNA-sequencing and genetic lineage tracing including exogenous barcodes and endogenous mitochondrial DNA mutations confirmed the reprogramming procession. Although the small chemical compound inhibiting spliceosome function only induces the differentiated hematopoietic progenitors to acquire plasticity and reprograms them into multipotent progenitors but not stem cells so far, this study still provides a proof-of-concept strategy for generating HSCs based on combining two independent steps together in future, first differentiating rare HSCs into large number of progenitors then reprogramming these progenitors into huge number of HSCs. Further dissecting the mechanism underlying spliceosome inhibitor-induced human hematopoietic cell reprogramming in future will help us comprehensively understanding not only the chemical reprogramming to generate desirable human cells for clinical translation but also hematopoiesis under physiological and pathological conditions.

Neutrophils in cancer carcinogenesis and metastasis.

In recent years, neutrophils have attracted increasing attention because of their cancer-promoting effects. An elevated neutrophil-to-lymphocyte ratio is considered a prognostic indicator for patients with cancer. Neutrophils are no longer regarded as innate immune cells with a single function, let alone bystanders in the pathological process of cancer. Their diversity and plasticity are being increasingly recognized. This review summarizes previous studies assessing the roles and mechanisms of neutrophils in cancer initiation, progression, metastasis and relapse. Although the findings are controversial, the fact that neutrophils play a dual role in promoting and suppressing cancer is undeniable. The plasticity of neutrophils allows them to adapt to different cancer microenvironments and exert different effects on cancer. Given the findings from our own research, we propose a reasonable hypothesis that neutrophils may be reprogrammed into a cancer-promoting state in the cancer microenvironment. This new perspective indicates that neutrophil reprogramming in the course of cancer treatment is a problem worthy of attention. Preventing or reversing the reprogramming of neutrophils may be a potential strategy for adjuvant cancer therapy.

Trajectory of chemical cocktail-induced neutrophil reprogramming.

Hematopoietic reprogramming holds great promise for generating functional target cells and provides new angle for understanding hematopoiesis. We reported before for the first time that diverse differentiated hematopoietic cell lineages could be reprogrammed back into hematopoietic stem/progenitor cell-like cells by chemical cocktail. However, the exact cell types of induced cells and reprogramming trajectory remain elusive. Here, based on genetic tracing method CellTagging and single-cell RNA sequencing, it is found that neutrophils could be reprogrammed into multipotent progenitors, which acquire multi-differentiation potential both in vitro and in vivo, including into lymphoid cells. Construction of trajectory map of the reprogramming procession shows that mature neutrophils follow their canonical developmental route reversely into immature ones, premature ones, granulocyte/monocyte progenitors, common myeloid progenitors, and then the terminal cells, which is stage by stage or skips intermediate stages. Collectively, this study provides a precise dissection of hematopoietic reprogramming procession and sheds light on chemical cocktail-induction of hematopoietic stem cells.

Overview on new progress of hereditary diffuse gastric cancer with CDH1 variants.

Hereditary diffuse gastric cancer (HDGC), comprising 1%-3% of gastric malignances, has been associated with CDH1 variants. Accumulating evidence has demonstrated more than 100 germline CDH1 variant types. E-cadherin encoded by the CDH1 gene serves as a tumor suppressor protein. CDH1 promoter hypermethylation and other molecular mechanisms resulting in E-cadherin dysfunction are involved in the tumorigenesis of HDGC. Histopathology exhibits characteristic signet ring cells, and immunohistochemical staining may show negativity for E-cadherin and other signaling proteins. Early HDGC is difficult to detect by endoscopy due to the development of lesions beneath the mucosa. Prophylactic gastrectomy is the most recommended treatment for pathogenic CDH1 variant carriers. Recent studies have promoted the progression of promising molecular-targeted therapies and management strategies. This review summarizes recent advances in CDH1 variant types, tumorigenesis mechanisms, diagnosis, and therapy, as well as clinical implications for future gene therapies.

Multidimensional study of the heterogeneity of leukemia cells in t(8;21) acute myelogenous leukemia identifies the subtype with poor outcome.

t(8;21)(q22;q22) acute myelogenous leukemia (AML) is morphologically characterized by a continuum of heterogeneous leukemia cells from myeloblasts to differentiated myeloid elements. Thus, t(8;21) AML is an excellent model for studying heterogeneous cell populations and cellular evolution during disease progression. Using integrative analyses of immunophenotype, RNA-sequencing (RNA-seq), and single-cell RNA-sequencing (scRNA-seq), we identified three distinct intrapatient leukemic cell populations that were arrested at different stages of myeloid differentiation: CD34+CD117dim blasts, CD34+CD117bri blasts, and abnormal myeloid cells with partial maturation (AM). CD117 is also known as c-KIT protein. CD34+CD117dim cells were blocked in the G0/G1 phase at disease onset, presenting with the regular morphology of myeloblasts showing features of granulocyte-monocyte progenitors (GMP), and were drug-resistant to chemotherapy. Genes associated with cell migration and adhesion (LGALS1, EMP3, and ANXA2) were highly expressed in the CD34+CD117dim population. CD34+CD117bri blasts were blocked a bit later than the CD34+CD117dim population in the hematopoietic differentiation stage and displayed high proliferation ability. AM cells, which bear abnormal myelocyte morphology, especially overexpressed granule genes AZU1, ELANE, and PRTN3 and were sensitive to chemotherapy. scRNA-seq at different time points identified CD34+CD117dim blasts as an important leukemic cluster that expanded at postrelapse refractory stage after several cycles of chemotherapy. Patients with t(8;21) AML with a higher proportion of CD34+CD117dim cells had significantly worse clinical outcomes than those with a lower CD34+CD117dim proportion. Univariate and multivariate analyses identified CD34+CD117dim proportion as an independent factor for poor disease outcome. Our study provides evidence for the multidimensional heterogeneity of t(8;21)AML and may offer new tools for future disease stratification.

Paclitaxel induces apoptosis through the TAK1-JNK activation pathway.

Paclitaxel (PTX) has previously been used to treat tumours of various tissue origins, such as lung, breast, ovarian, prostate cancers and leukemia. PTX-induced apoptosis is associated with p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), nuclear factor-kappa B (NF-κB) and c-Jun N-terminal kinase or stress-activated protein kinase (JNK/ SAPK) pathways. Transforming growth factor-beta-activated kinase 1 (TAK1) and TAK1-binding protein 1 (TAB1) play an important role in cell apoptosis through the p38, ERK, NF-κB and JNK signal transduction pathways. To investigate the role of TAK1 in PTX-induced cell apoptosis, we treated HEK293 and 8305C cells with 0-20 µM PTX for 6, 12 or 24 h. To investigate whether TAK1 can cooperate with PTX for cancer treatment, we transfected cells with TAK1, TAB1 or control plasmid and treated them with PTX (3-10 µM) for 9-24 h. Apoptosis rates were analysed by flow cytometry (Annexin V/PI). Endogenous TAK1 and TAB1, caspase-7 cleavage, poly ADP-ribose polymerase (PARP) cleavage, Bcl-xL level, phospho-p44/42, phospho-JNK and phospho-p38 were detected by western blot. We show that in HEK293 and 8305C cells, PTX enhanced the endogenous TAK1/TAB1 level and induced cell apoptosis in a dose- and time-dependent manner. Upon TAK1 overexpression in HEK293 cells treated with PTX, apoptosis rate, JNK phosphorylation and PARP cleavage increased contrary to heat-shocked or untreated cells. CRISPR editing of the tak1 gene upon PTX treatment resulted in lower phospho-JNK and PARP cleavage levels than in cells transfected with the control or the TAK1- or TAB1 + TAK1-containing plasmids. TAK1-K63A could not induce JNK phosphorylation or PARP cleavage. We conclude that PTX induces HEK293 and 8305C cell apoptosis through the TAK1-JNK activation pathway, potentially highlighting TAK1's role in chemosensitivity.

Chemical Cocktail Induces Hematopoietic Reprogramming and Expands Hematopoietic Stem/Progenitor Cells.

Generation of hematopoietic stem/progenitor cells (HSPCs) via cell expansion or cell reprogramming has been widely achieved by overexpression of transcription factors. Herein, it is reported that without introducing exogenous genes, mouse fibroblasts can be reprogrammed into hemogenic cells based on lineage tracing analysis, which further develop into hematopoietic cells, by treatment of cocktails of chemical compounds. The chemical cocktails also reprogram differentiated hematopoietic cells back into HSPC-like cells. Most importantly, the chemical cocktails enabling hematopoietic reprogramming robustly promote HSPC proliferation ex vivo. The expanded HSPCs acquire enhanced capacity of hematopoietic reconstruction in vivo. Single-cell sequencing analysis verifies the expansion of HSPCs and the cell reprogramming toward potential generation of HSPCs at the same time by the chemical cocktail treatment. Thus, the proof-of-concept findings not only demonstrate that hematopoietic reprogramming can be achieved by chemical compounds but also provide a promising strategy for acquisition of HSPCs by chemical cocktail-enabled double effects.

Reprogramming of Fibroblasts to Neural Stem Cells by a Chemical Cocktail.

Chemically induced cell fate conversion, including reprogramming to pluripotent stem cells and direct reprogramming to somatic cells, has been proved to be an alternative strategy with many advantages, in comparison with conventional transcription factors- or microRNAs-enabled cell reprogramming. Many functional and desirable cells have been generated via the chemically induced reprogramming. Neural stem cells (NSCs) hold great potential in basic research and clinical application. Here, we describe a detailed protocol for converting mouse fibroblasts into NSCs by a cocktail of chemical compounds.

Cellular Reprogramming as a Therapeutic Target in Cancer.

Cancer heterogeneity has long been recognized as an important clinical determinant of patient outcomes and, thus, many new cancer treatments have been designed to target these different cells. Despite the short-term achievements of current therapies, including chemotherapy, antiangiogenesis therapy, radiotherapy, and immunotherapy, the long-term success of cancer regression remains poor. Therefore, researchers have investigated a new property, cellular reprogramming, in cancer that not only contributes to the classic hallmarks of cancer, but also suggests that cancer is a dynamic event rather than a static cellular entity. Here, we discuss the mechanisms by which the cellular reprogramming of cancer cells can explain some of the phenotypic and functional heterogeneity observed among cancer cells.

Direct Conversion of Mouse Fibroblasts into Neural Stem Cells by Chemical Cocktail Requires Stepwise Activation of Growth Factors and Nup210.

Neural stem cells (NSCs) are valuable for both basic research and clinical application. We previously reported a chemical cocktail that could reprogram somatic cells into neural progenitor cells. However, the reprogramming process is complex, and the underlying mechanism remains largely elusive. Here, we identified a culture condition that greatly promotes the efficiency of NSC generation directly from mouse fibroblasts based on our reported chemical cocktail. Transcriptome and epigenome analyses demonstrated that growth factors including IL-6, FGF5, and LIF were dynamically activated and contributed to the cell fate changes. Treatment of these growth factors together can enable fibroblast to neural progenitor-like cell conversion. Moreover, the reprogramming capacity of both chemical cocktail and growth factors requires nucleoporin Nup210 to activate SoxB1 transcription factors to initiate NSC fate. Altogether, our findings reveal important roles of both extracellular signals and internal factors in direct cellular reprogramming.

Low CLL-1 Expression Is a Novel Adverse Predictor in 123 Patients with De Novo CD34+ Acute Myeloid Leukemia.

Recent reports state that C-type lectin-like molecule-1 (CLL-1) in acute myeloid leukemia (AML) is expressed primarily on myeloid cells, but there is still no investigation about its prognostic significance on leukemic blast compartment. Hence, this study aimed to evaluate the prognostic value of CLL-1 in 123 patients with de novo CD34+ Non-M3 AML. Multiparameter flow cytometry was used to assess the expression of CLL-1 on immature compartment in AML and control groups. We found that CLL-1 expression level on blast compartment was closely linked to clinical characteristics, treatment response, and survival outcome of patients. Decreased expression of CLL-1 was observed on immature compartment from AML patients as compared with controls (62.6% vs. 86.5%, P < 0.05). Logistic model exhibited that CLL-1low independently predicted low complete remission rate with an odds ratio of 4.57 (2.53-6.61, P < 0.05). Additionally, CLL-1 expression level at diagnosis was inversely correlated to the residual blast cells (residual leukemia cell) after induction chemotherapy (r = -0.423, P < 0.05). Furthermore, multivariate Cox regression model demonstrated that CLL-1low was still an independent adverse predictor (P < 0.05 for event-free survival, P < 0.05 for overall survival). Notably, CLL-1low was able to discriminate poor survival patients from intermediate- and favorable-risk groups. Taken together, CLL-1 is a novel prognostic predictor that could be exploited to supplement the current AML prognostic risk stratification system, and potentially optimize the clinical management of AML.

Clinical significance of day 5 peripheral blast clearance rate in the evaluation of early treatment response and prognosis of patients with acute myeloid leukemia.

BACKGROUND: Minimal residual disease detection in the bone marrow is usually performed in patients with acute myeloid leukemia undergoing one course of induction chemotherapy. To optimize the chemotherapy strategies, more practical and sensitive markers are needed to monitor the early treatment response during induction. For instance, peripheral blood (PB) blast clearance rate may be considered as such a monitoring marker. METHODS: PB blasts were monitored through multiparameter flow cytometry (MFC). Absolute counts were determined before treatment (D0) and at specified time points of induction chemotherapy (D3, D5, D7, and D9). The cut-off value of D5 peripheral blast clearance rate (D5-PBCR) was defined through receiver operating characteristic (ROC) analysis. Prognostic effects were compared among different patient groups according to D5-PBCR cut-off value. RESULTS: D5-PBCR cut-off value was determined as 99.55%. Prognostic analysis showed that patients with D5-PBCR ≥99.55% more likely achieved complete remission (94.6% vs. 56.1%, P < 0.001) and maintained a relapse-free status than other patients (80.56% vs. 57.14%, P = 0.027). Survival analysis revealed that relapse-free survival (RFS) and overall survival (OS) were longer in patients with D5-PBCR ≥99.55% than in other patients (two-year OS: 71.0% vs. 38.7%, P = 0.011; two-year RFS: 69.4% vs. 30.7%, P = 0.026). In cytogenetic-molecular intermediate-risk group, a subgroup with worse outcome could be distinguished on the basis of D5-PBCR (<99.55%; OS: P = 0.033, RFS: P = 0.086). CONCLUSIONS: An effective evaluation method of early treatment response was established by monitoring PB blasts through MFC. D5-PBCR cut-off value (99.55%) can be a reliable reference to predict treatment response and outcome in early stages of chemotherapy. The proposed marker may be used in induction regimen modification and help optimize cytogenetic-molecular prognostic risk stratification.

DNMT3A Arg882 mutation drives chronic myelomonocytic leukemia through disturbing gene expression/DNA methylation in hematopoietic cells.

The gene encoding DNA methyltransferase 3A (DNMT3A) is mutated in ∼20% of acute myeloid leukemia cases, with Arg882 (R882) as the hotspot. Here, we addressed the transformation ability of the DNMT3A-Arg882His (R882H) mutant by using a retroviral transduction and bone marrow transplantation (BMT) approach and found that the mutant gene can induce aberrant proliferation of hematopoietic stem/progenitor cells. At 12 mo post-BMT, all mice developed chronic myelomonocytic leukemia with thrombocytosis. RNA microarray analysis revealed abnormal expressions of some hematopoiesis-related genes, and the DNA methylation assay identified corresponding changes in methylation patterns in gene body regions. Moreover, DNMT3A-R882H increased the CDK1 protein level and enhanced cell-cycle activity, thereby contributing to leukemogenesis.

Functional features of RUNX1 mutants in acute transformation of chronic myeloid leukemia and their contribution to inducing murine full-blown leukemia.

The BCR-ABL fusion protein generated by t(9;22)(q34;q11) in chronic myeloid leukemia (CML) plays an essential role in the pathogenesis of the myeloproliferative disorder status at the chronic phase of the disease, but progression from the chronic phase to blast crisis (BC) is believed to require additional mutations. To explore the underlying mechanisms for BC, which is characterized by a blockage of blood cell differentiation, we screened several genes crucial to hematopoiesis and identified 10 types of mutations in RUNX1 among 11 of 85 (12.9%) patients with acute transformation of CML. Most of the mutations occurred in the runt homology domain, including H78Q, W79C, R139G, D171G, R174Q, L71fs-ter94, and V91fs-ter94. Further studies indicated that RUNX1 mutants not only exhibited decreased transactivation activity but also had an inhibitory effect on the WT RUNX1. To investigate the leukemogenic effect of mutated RUNX1, H78Q and V91fs-ter94 were transduced into 32D cells or BCR-ABL-harboring murine cells, respectively. Consistent with the myeloblastic features of advanced CML patients with RUNX1 mutations, H78Q and V91fs-ter94 disturbed myeloid differentiation and induced a BC or accelerated phase-like phenotype in mice. These results suggest that RUNX1 abnormalities may promote acute myeloid leukemic transformation in a subset of CML patients.

C-KIT mutation cooperates with full-length AML1-ETO to induce acute myeloid leukemia in mice.

The full-length AML1-ETO (AE) fusion gene resulting from t(8;21)(q22;q22) in human acute myeloid leukemia (AML) is not sufficient to induce leukemia in animals, suggesting that additional mutations are required for leukemogenesis. We and others have identified activating mutations of C-KIT in nearly half of patients with t(8;21) AML. To test the hypothesis that activating C-KIT mutations cooperate with AE to cause overt AML, we generated a murine transduction and transplantation model with both mutated C-KIT and AE. To overcome the intracellular transport block of human C-KIT in murine cells, we engineered hybrid C-KIT (HyC-KIT) by fusing the extracellular and transmembrane domains of the murine c-Kit in-frame to the intracellular signaling domain of human C-KIT. We showed that tyrosine kinase domain mutants HyC-KIT N822K and D816V, as well as juxtamembrane mutants HyC-KIT 571+14 and 557-558Del, could transform murine 32D cells to cytokine-independent growth. The protein tyrosine kinase inhibitor dasatinib inhibited the proliferation of 32D cells expressing these C-KIT mutants, with potency in the low nanomolar range. In mice, HyC-KIT N822K induced a myeloproliferative disease, whereas HyC-KIT 571+14 induces both myeloproliferative disease and lymphocytic leukemia. Interestingly, coexpression of AE and HyC-KIT N822K led to fatal AML. Our data have further enriched the two-hit model that abnormalities of both transcription factor and membrane/cytosolic signaling molecule are required in AML pathogenesis. Furthermore, dasatinib prolonged lifespan of mice bearing AE and HyC-KIT N822K-coexpressing leukemic cells and exerted synergic effects while combined with cytarabine, thus providing a potential therapeutic for t(8;21) leukemia.

NOTCH1 mutations in T-cell acute lymphoblastic leukemia: prognostic significance and implication in multifactorial leukemogenesis.

PURPOSE: NOTCH signaling pathway is essential in T-cell development and NOTCH1 mutations are frequently present in T-cell acute lymphoblastic leukemia (T-ALL). To gain insight into its clinical significance, NOTCH1 mutation was investigated in 77 patients with T-ALL. EXPERIMENTAL DESIGN: Detection of NOTCH1 mutation was done using reverse transcription-PCR amplification and direct sequencing, and thereby compared according to the clinical/biological data of the patients. RESULTS: Thirty-two mutations were identified in 29 patients (with dual mutations in 3 cases), involving not only the heterodimerization and proline/glutamic acid/serine/threonine domains as previously reported but also the transcription activation and ankyrin repeat domains revealed for the first time. These mutations were significantly associated with elevated WBC count at diagnosis and independently linked to short survival time. Interestingly, the statistically significant difference of survival according to NOTCH1 mutations was only observed in adult patients (>18 years) but not in pediatric patients (< or = 18 years), possibly due to the relatively good overall response of childhood T-ALL to the current chemotherapy. NOTCH1 mutations could coexist with HOX11, HOX11L2, or SIL-TAL1 expression. The negative effect of NOTCH1 mutation on prognosis was potentiated by HOX11L2 but was attenuated by HOX11. CONCLUSION: NOTCH1 mutation is an important prognostic marker in T-ALL and its predictive value could be even further increased if coevaluated with other T-cell-related regulatory genes. NOTCH pathway thus acts combinatorially with oncogenic transcriptional factors on T-ALL pathogenesis.

AML1-ETO and C-KIT mutation/overexpression in t(8;21) leukemia: implication in stepwise leukemogenesis and response to Gleevec.

To explore the genetic abnormalities that cooperate with AML1-ETO (AE) fusion gene to cause acute myeloid leukemia (AML) with t(8;21), we screened a number of candidate genes and identified 11 types of mutations in C-KIT gene (mC-KIT), including 6 previously undescribed ones among 26 of 54 (48.1%) cases with t(8;21). To address a possible chronological order between AE and mC-KIT, we showed that, among patients with AE and mC-KIT, most leukemic cells at disease presentation harbored both genetic alteration, whereas in three such cases investigated during complete remission, only AE, but not mC-KIT, could be detected by allele-specific PCR. Therefore, mC-KIT should be a subsequent event on the basis of t(8;21). Furthermore, induced expression of AE in U937-A/E cells significantly up-regulated mRNA and protein levels of C-KIT. This may lead to an alternative way of C-KIT activation and may explain the significantly higher C-KIT expression in 81.3% of patients with t(8;21) than in patients with other leukemias. These data strongly suggest that t(8;21) AML follows a stepwise model in leukemogenesis, i.e., AE represents the first, fundamental genetic hit to initiate the disease, whereas activation of the C-KIT pathway may be a second but also crucial hit for the development of a full-blown leukemia. Additionally, Gleevec suppressed the C-KIT activity and induced proliferation inhibition and apoptosis in cells bearing C-KIT N822K mutation or overexpression, but not in cells with D816 mC-KIT. Gleevec also exerted a synergic effect in apoptosis induction with cytarabine, thus providing a potential therapeutic for t(8;21) leukemia.