Progression Of Chronic Myelogenous Leukemia Research Articles

Long-term results of therapy for chronic myeloid leukemia: a 20-year analysis of the use of tyrosine kinase inhibitors in Russia

Introduction. In Russia, within the framework of the GIPAP program, in the period from 2001 to 2007 at the National Medical Research Center for Hematology, imatinib therapy was initiated in 235 patients in the chronic phase of chronic myelogenous leukemia (CML).Aim: to analyze the long-term results of therapy in patients with CML who started imatinib therapy as part of the GIPAP program.Methods. A retrospective analysis of the results of therapy was performed in 235 patients with СР CML, who received imatinib under the GIPAP program from 2001 to 2007 at the National Medical Research Center for Hematology. The protocols for therapy and monitoring of the residual disease of patients at various time intervals were determined by the clinical recommendations relevant at that time in the conditions of real clinical practice and the possibilities of the patient’s region of residence. Overall survival and survival without discontinuation of imatinib therapy, univariate and multivariate analysis of overall survival were performed. The cumulative incidence of responses was calculated. An analysis of response factors, the probability of death from concomitant diseases and death from CML was carried out.Results. The median follow-up of living patients at the time of analysis was 17.3 years (IQR 15.5–18.5). 70 (30 %) patients died, with the median time to death from the start of therapy being 7.8 years (IQR 3.7–13.6). The overall 10-year, 15-year and 20-year survival rates were 82 %, 74 % and 62 %. The cause of death in 43 cases (61%) was the progression of CML to the phase of acceleration or blast crisis and death out of remission for an unspecifi ed cause. 27 (39%) patients died from causes not related to CML. Patient age at initiation of imatinib therapy, length of time from diagnosis to initiation of imatinib therapy, and Sokal and ELTS risk groups at disease onset were identifi ed as signifi cant for survival by univariate analysis. Multivariate analysis showed independent predictive value for overall survival for age at initiation of imatinib therapy, length of illness before imatinib treatment, and ELTS risk group at disease onset. Among patients who died from CML progression, the proportion of patients who did not achieve CCyR for the entire period of therapy before death was 83% (35/42), while among patients who died from concomitant diseases, the proportion of patients without CCyR for the entire period of therapy was 11 % (p < 0.0001). The median duration of imatinib therapy was 11.4 years (0.8–21 years). 40 people died during imatinib therapy, 103 patients are alive and continue therapy with imatinib, 92 patients received at least one second-generation of Tyrosine kinase inhibitors (TKI) (TKI2), of which 62 people are alive and continue treatment with TKI. No more than two lines of TKI therapy were received by 49 (21 %) patients, and three or more lines were prescribed to 43 (18 %) patients. The median duration of therapy after switching to TKI2 was 7.8 years (0.1–15.6 years). Overall 15-year survival after switching to TKI2 was 59 %. On therapy with imatinib, during the entire observation period, complete cytogenetic response (CCyR) was achieved in 171 patients (73 %), another 18 patients (8 %) achieved CCyR for the fi rst time after switching to TKI2. Major (MMR) and deep molecular response (DMR) were achieved with imatinib in 129 (56 %) and 124 (53 %) patients, with TKI2 TKI2 therapy in 38 (16 %) and 33 (14 %) patients, respectively. Multivariate analysis showed an independent predictive value of only the time period from diagnosis to the start of imatinib treatment for achieving molecular responses to TKI therapy.Conclusion. After 20 years of monitoring patients on TKI therapy, we still cannot say that survival in CML is comparable to the survival of normal population. Long-term follow-up confi rms the fact that tumor reduction to at least the level of CCyR is the most signifi cant surrogate marker associated with a reduced risk of death from CML. Timely diagnosis of the disease, rapid initiation of targeted therapy and the fastest possible induction of cytogenetic and molecular responses is a very important mechanism for reducing the risk of resistant course and progression of CML.

Precision Isolation of Circulating Leukemia Cells in Chronic Myelogenous Leukemia Patients Using a Novel Microfluidic Device and Its Clinical Applications

Chronic Myelogenous Leukemia (CML) is a prevalent hematologic malignancy characterized by the malignant transformation of myeloid cells and their proliferation in the peripheral blood. The management of CML poses significant challenges, particularly in detecting and eradicating minimal residual disease, which is crucial for preventing relapse and improving survival outcomes. Traditional minimal residual disease detection methods, such as bone marrow aspiration, are invasive and have limitations which include the potential for sampling errors and false negatives. This study introduces a novel label-free microfluidic chip designed for the segregation and recovery of circulating leukemia cells, offering a non-invasive liquid biopsy approach with potential applications in precision medicine. Over July 2021 to October 2023, we recruited 56 CML patients across various disease stages and collected blood samples for analysis using our microfluidic device. The device demonstrated high efficacy in isolating circulating leukemia cells, with an optimal capture efficiency of 78% at a sample flow rate of 3 mL/h. Our results indicate that the microfluidic device can efficiently segregate and quantify circulating leukemia cells, providing a detailed understanding of CML progression and treatment response. The significant reduction in circulating leukemia cell counts in patients in complete remission highlights the device’s potential in monitoring treatment efficacy. Furthermore, the device’s sensitivity in detecting minimal residual disease could offer a more reliable prognostic tool for therapeutic decision-making in CML management.

Upregulation of SNHG7 and FAIM2 Expression Levels in Chronic Myelogenous Leukemia Patients Compared with Normal Subjects

Background: Chronic myelogenous leukemia (CML), also known as chronic granulocytic leukemia (CGL), is considered a hematological malignancy with a prevalence of 1.9 per 100,000 population. Recent studies have shown the role of SNHGs in proliferation, apoptosis, CML progression, and even drug resistance through interaction with miRNAs. The positive correlation between lncRNA-small nucleus RNA host gene 7 (SNHG7) and Fas apoptosis inhibitory molecule 2 (FAIM2) with different cancers has been proved. Objectives: This study investigated the role of SNHG7 and FAIM2 in CML for the first time and revealed the potential correlation between these genes. Methods: This research was performed with a case-control design. First, the patients were confirmed by using karyotype in addition to molecular and cellular methods. After RNA extraction from white blood cells and cDNA synthesis, gene expression was measured with the use of real-time PCR. Finally, the data were statistically analyzed. Results: The results of this study showed that the expression levels of SNHG7 and FAIM2 were significantly increased in chronic myelogenous leukemia patients compared with normal individuals (P-value < 0.001). This increased expression may indicate a potential role for this molecule in the progression and development of this cancer. Conclusions: The current study demonstrates the effective roles of SNHG7 and FAIM2 in the progression of chronic myeloid leukemia, which can be investigated in future studies as biomarkers and potential therapeutic targets.

MiR-494 in Extracellular Vesicles as a Potent Biomarker of Chronic Myeloid Leukemia Treatment with Tyrosine Kinase Inhibitors

Extracellular vesicles (EVs) are nano-sized particles released from cells and transferring molecules (proteins, lipids and nucleic acids such as mRNA, tRNA and miRNA) to recipient cells. Surface antigens and components are important for the functions as cell-to-cell communication of EVs. Thus, EVs are useful biomarkers for various diseases including leukemias and other types of malignancies. We evaluated whether miRNAs in EVs released from chronic myelogenous leukemia (CML) cells could be used for diagnosis. Microarray analysis of miRNAs in EVs obtained from the culture supernatants of two CML cell lines showed that miR-494 and miR-373-5p were significantly decreased by tyrosine kinase inhibitor for BCR-ABL1. Validation analysis with Taqman-based qRT-PCR of whole serum obtained patients with CML in the chronic phase (n = 5) did not show a significant difference in miR-494 levels compared to the CML accelerated phase and blast crisis patients (n = 5). However, the levels of miR-494 were 2.9-fold higher in the accelerated phase or blast crisis than in the chronic phase (p < 0.05). These results indicate that it is important to measure miR-494 using only EVs rather than whole serum. Our data suggest that EV-miR-494 is a useful biomarker of CML progression and evaluation of response to tyrosine kinase inhibitors.

The impact of gene-body H3K36me3 patterns on gene expression level changes in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a malignant clonal disease of hematopoietic stem cells. Researches have exhibited that the progression of CML is related to histone modifications. Here, we perform the systematic analyses of H3K36me3 patterns and gene expression level changes. We observe that the genes with higher gene-body H3K36me3 levels in normal cells show fewer expression changes during leukemogenesis, while the genes with lower gene-body H3K36me3 levels in normal cells yield obvious expression changes during leukemogenesis (ρ=-0.98, P=9.30×10-8). These findings are conserved in human lung/breast cancers and mouse CML, regardless of gene expression levels and gene lengths. Regulatory element analysis and Random Forest regression display that Hoxd13, Rara, Scl, Smad3, Smad4 and Tgif1 induce the up-regulation of genes with lower H3K36me3 levels (ρ=0.97, P=2.35×10-56). Enrichment analysis shows that the differentially expressed genes with lower H3K36me3 levels are involved in leukemia-related pathways, such as leukocyte migration and regulation of leukocyte activation. Finally, six driver genes (Tp53, Wt1, Dnmt3a, Cacna1b, Phactr1 and Gbp4) with lower H3K36me3 levels are identified. Our analyses indicate that lower gene-body H3K36me3 levels may serve as a biomarker for the progression of CML.

Role of Signal Transducing Adaptor Protein (STAP) Family in Chronic Myelogenous Leukemia

Role of Signal Transducing Adaptor Protein (STAP) Family in Chronic Myelogenous Leukemia

Identification of Key Histone Modifications and Their Regulatory Regions on Gene Expression Level Changes in Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a type of cancer with a series of characteristics that make it particularly suitable for observations on leukemogenesis. Research have exhibited that the occurrence and progression of CML are associated with the dynamic alterations of histone modification (HM) patterns. In this study, we analyze the distribution patterns of 11 HM signals and calculate the signal changes of these HMs in CML cell lines as compared with that in normal cell lines. Meanwhile, the impacts of HM signal changes on expression level changes of CML-related genes are investigated. Based on the alterations of HM signals between CML and normal cell lines, the up- and down-regulated genes are predicted by the random forest algorithm to identify the key HMs and their regulatory regions. Research show that H3K79me2, H3K36me3, and H3K27ac are key HMs to expression level changes of CML-related genes in leukemogenesis. Especially H3K79me2 and H3K36me3 perform their important functions in all 100 bins studied. Our research reveals that H3K79me2 and H3K36me3 may be the core HMs for the clinical treatment of CML.

Coexistence of recurrent chromosomal abnormalities and the Philadelphia chromosome in acute and chronic myeloid leukemias: report of five cases and review of literature

Progression of chronic myelogenous leukemia (CML) is frequently accompanied by cytogenetic evolution. Additional genetic abnormalities are seen in 10–20% of CML cases at the time of diagnosis, and in 60–80% of cases of advanced disease. Unbalanced chromosomal changes such as an extra copy of the Philadelphia chromosome (Ph), trisomy 8, and i(17)(q10) are common. Balanced chromosomal translocations, such as t(3;3), t(8;21), t(15;17), and inv(16) are typically found in acute myeloid leukemia, but rarely occur in CML. Translocations involving 11q23, t(8;21), and inv(16) are relatively common genetic abnormalities in acute leukemia, but are extremely rare in CML. In the literature to date, there are at least 76 Ph+ cases with t(3;21), 47 Ph+ cases with inv(16), 16 Ph+ cases with t(8;21), and 9 Ph+ cases with t(9;11). But most of what has been published is now over 30 years old, without the benefit of modern immunophenotyping to confirm diagnosis, and before the introduction of treatment regimes such as TKI. In this study, we explored the rare concomitant occurrence of coexistence current chromosomal translocation and t(9;22) in CML or acute myeloid leukemia (AML).

Epigenetic silencing of the DAPK1 gene in Egyptian patients with chronic myeloid Leukemia

BackgroundEpigenetics play a crucial role in the carcinogenesis of hematological malignancies. Alterations of the methylation status in the promoter region of tumor suppressor genes, such as DAPK1, cause loss of gene function and subsequent progression of Chronic Myelogenous Leukemia (CML) to more advanced stages. This study aimed to analyze the methylation status of the DAPK1 gene promoter in different phases of CML patients. Material and methodsThe study included 200 CML patients positive for BCR/ABL and 50 as control. Clinicopathological examination was done for all patients. DAPK1 gene methylation was determined by the Methylation Specific-PCR method. ResultsDAPK1 promoter methylation was evident in 37.0% of CML patients and it was more frequent in affected females than males (p = 0.014). Platelet count and bone marrow blast cells were significantly different in the methylated group compared to the unmethylated group (p = 0.001 and p = 0.034 respectively). Out of the methylated group, fifteen patients had a hemimethylated pattern. Unmethylation was more frequent in patients in the chronic phase (66.5%; p = 0.001). In contrast, methylation was found in 75.0% of patients in the accelerated phase (p = 0.040) with an odds ratio (OR) of 5.470 (95% CI: 1.074–27.849). Similarly, methylation was found in 85.7% of patients in the blast phase (p = 0.027) where the OR increased to 11.029 (95% CI: 1.300–93.513). By logistic regression analysis, there was significant association between methylation pattern and CML disease clinical outcome. ConclusionCML progression is closely associated with methylation changes in the DAPK1 promoter region. Identification of the underlying epigenetic mechanisms in CML is valuable in predicting disease prognosis and offering suitable management for each patient.

Players in Drug-Resistant Leukemia Stem/Initiating Cells and Immunity in Patients with CML in Context of Oxygen Levels: Would Collecting/Processing Cells in Hypoxia Offer Additional Information? A Next Frontier of Investigation.

Chronic myelogenous leukemia (CML) is a stem cell disorder once considered an eventual death sentence upon progression to the terminal acute/blastic cell phase, a terrible clinical outcome that has improved with the introduction of tyrosine kinase inhibitors. A major continuing problem with treating CML is the persistence of drug-resistant leukemia stem/initiating cells (LS/IC). In this issue of Blood Cancer Discovery, Silvestri and colleagues describe an incredibly in-depth mechanistic study using genetic and pharmacologic modulation of the miRNA MiR300 with and without treatment with activators of the serine-threonine protein phosphatase 2A (PP2A) in human cells. In vitro studies and in vivo mouse models of patient-derived xenografts were used to address the need to target LS/ICs and restore immunity of impaired natural killer cells for attenuation of CML progression. See related article by Silvestri et al., p. 48.

K562 cell-derived exosomes suppress the adhesive function of bone marrow mesenchymal stem cells via delivery of miR-711

A failure of bone marrow mesenchymal stem cells (BM-MSCs) to adhere to hematopoietic cells is an essential cause of the progression of chronic myelogenous leukemia and is also a cause of failure of bone marrow (BM) transplantation, but the exact mechanisms of this have not been fully elucidated. Recent studies have indicated that microRNAs (miRNAs) are contained in leukemia-derived exosomes and are involved in modulating the BM microenvironment. In this study, we found that K562 cell-derived exosomes transfer miR-711 to BM-MSCs and suppress the adhesive function of BM-MSCs. Using qRT-PCR, we also confirmed a significantly higher level of miR-711 in exosomes derived from K562 cells than in exosomes derived from parental cells. The BM-MSCs co-cultured with exosomes derived from K562 cells showed a lower adhesion rate than did controls. We further demonstrated that exosomal transfer of miR-711 induced decreased adhesive abilities by inhibiting expression of adhesion molecule CD44 in BM-MSCs. In conclusion, our study reveals that K562 cell-derived exosomal miR-711 can be transferred to BM-MSCs and weaken adhesive abilities by silencing the expression of the adhesion molecule CD44.

Xanthohumol, a Prenylated Flavonoid from Hops, Induces Caspase-Dependent Degradation of Oncoprotein BCR-ABL in K562 Cells.

BCR-ABL oncoprotein drives the initiation, promotion, and progression of chronic myelogenous leukemia (CML). Tyrosine kinase inhibitors are the first choice for CML therapy, however, BCR-ABL mediated drug resistance limits its clinical application and prognosis. A novel promising therapeutic strategy for CML therapy is to degrade BCR-ABL using small molecules. Antioxidant xanthohumol (XN) is a hop-derived prenylated flavonoid with multiple bioactivities. In this study, we showed XN could inhibit the proliferation, induce S phase cell cycle arrest, and stimulate apoptosis in K562 cells. XN degraded BCR-ABL in a concentration- and time-dependent manner, and the involved degradation pathway was caspase activation, while not autophagy induction or ubiquitin proteasome system (UPS) activation. Moreover, we revealed for the first time that XN could inhibit the UPS and autophagy in K562 cells, and the inhibitory effect of XN on autophagy could attenuate imatinib-induced autophagy and enhance the therapeutic efficiency of imatinib in K562 cells. Our present findings identified XN act as a degrader of BCR-ABL in K562 cells, and XN had potential to be developed as an alternate agent for CML therapy.

Long Noncoding RNA (lncRNA) Small Nucleolar RNA Host Gene 5 (SNHG5) Regulates Proliferation, Differentiation, and Apoptosis of K562 Cells in Chronic Myeliod Leukemia

BackgroundHuman chronic myelogenous leukemia (CML) is a hematopoietic stem cell disorder with high malignant and invasive activity. lncRNA SNHG5 has been reported to be upregulated in CML. However, whether it affects the proliferation, differentiation, and apoptosis in CML cells is still unknown. This study investigated the role of SNHG5 in CML and revealed the potential mechanism.Material/MethodsK562 cells were transfected with shRNA, and the expression level of SNHG5 was assessd by quantitative RT-PCR. The proliferation ability was determined by CCK-8 assay. Western blot analysis was performed to detect protein expressions related to cell proliferation, differentiation, and apoptosis. Cell apoptosis rate was analyzed by flow cytometry. The DNA methylation level was determined by methylation-specific PCR (MSP).ResultsOur results show that inhibition of SNHG5 induced by RNA interference significantly inhibits K562 cells proliferation and induces cell differentiation with the increased expression of CD42b, CD11b, CD14, GATA-1, and β-globin. Flow cytometry analysis indicated that inhibition of SNHG5 significantly induced cell apoptosis with decreased expression of Bcl-2 and increased expression of Bax and cleaved capase-3. Additionally, Western blot and MSP analyses confirmed that inhibition of SNHG5 increased the expression of DR4 gene through suppressing its methylation.ConclusionsInhibition of SNHG5 suppressed K562 cell proliferation through inducing the differentiation and apoptosis by inhibiting methylation of DR4. Therefore, downregulated SNHG5 could play a key role in CML progression, and might provide a new strategy for the treatment of CML.

Impact of Additional Chromosomal Aberrations on the Disease Progression of Chronic Myelogenous Leukemia.

The emergence of additional chromosomal abnormalities (ACAs) in Philadelphia chromosome/BCR-ABL1 positive chronic myeloid leukemia (CML), is considered to be a feature of disease evolution. However, their frequency of incidence, impact on prognosis and treatment response effect in CML is not conclusive. In the present study, we performed a chromosome analysis of 489 patients in different clinical stages of CML, using conventional GTG-banding, Fluorescent in situ Hybridization and Spectral Karyotyping. Among the de novo CP cases, ACAs were observed in 30 patients (10.20%) with lowest incidence, followed by IM resistant CP (16.66%) whereas in AP and BC, the occurrence of ACAs were higher, and was about 40.63 and 50.98%, respectively. The frequency of occurrence of ACAs were compared between the study groups and it was found that the incidence of ACAs was higher in BC compared to de novo and IM resistant CP cases. Likewise, it was higher in AP patients when compared between de novo and IM resistant CP cases, mirroring the fact of cytogenetic evolution with disease progression in CML. In addition, we observed 10 novel and 10 rare chromosomal aberrations among the study subjects. This study pinpoints the fact that the genome of advanced phase patients was highly unstable, and this environment of genomic instability is responsible for the high occurrence of ACAs. Treatment response analysis revealed that compared to initial phases, ACAs were associated with an adverse prognostic effect during the progressive stages of CML. This study further portrayed the cytogenetic mechanism of disease evolution in CML.

Discovery of the Oncogenic Parp1, a Target of bcr-abl and a Potential Therapeutic, in mir-181a/PPFIA1 Signaling Pathway

miR-181a is downregulated in leukemia and affects its progression, drug resistance, and prognosis. However, the exact mechanism of its targets in leukemia, particularly in chronic myelogenous leukemia (CML), has not previously been established. Here, we use a multi-omics approach to demonstrate that protein tyrosine phosphatase, receptor type, f polypeptide, leukocyte common antigen (LAR) interacting protein (liprin), alpha 1 (PPFIA1) is a direct target for miR-181a in CML. Phospho-array assay shows that multiple phosphorylated proteins, particularly KIT signaling molecules, were downregulated in PPFIA1 inhibition. Additionally, PPFIA1 bound PARP1, a common molecule downstream of both PPFIA1 and BCR/ABL, to upregulate KIT protein through activation of nuclear factor kappa B (NF-κB)-P65 expression. Targeted inhibition of PPFIA1 and PARP1 downregulated c-KIT level, inhibited CML cell growth, and prolonged mouse survival. Overall, we report a critical regulatory miR-181a/PPFIA1/PARP1/NF-κB-P65/KIT axis in CML, and our preclinical study supports that targeted PPFIA1 and PARP1 may serve as a potential CML therapy.

DUXAP10 regulates proliferation and apoptosis of chronic myeloid leukemia via PTEN pathway.

To investigate the role of DUXAP10 in chronic myelogenous leukemia (CML) and its underlying mechanism. We detected DUXAP10 expression in 82 CML patients, 12 normal controls, and CML cell line by qRT-PCR (quantitative real-time polymerase chain reaction). After transfection of si-DUXAP10 or si-PTEN in CML cell lines (K652, KG-1), we detected proliferation, cell cycle, and apoptosis by CCK-8 (cell counting kit-8), colony formation assay, and flow cytometry, respectively. Finally, protein expressions of p21, CDK2, Bcl-2, Bax, and PTEN were detected by Western blot. DUXAP10 was upregulated in CML tissues and cells, which was gradually increased in the chronic phase (CP), acceleration phase (AP), and blast phase (BP) of CML. Knockdown of DUXAP10 in K652 and KG-1 cells can remarkably inhibit cell proliferation, promote cycle arrest and apoptosis. Western blot and flow cytometry results demonstrated that DUXAP10 can reduce apoptosis by inhibiting PTEN expression. Overexpressed DUXAP10 accelerates the development and progression of CML by promoting cell proliferation, reducing cell cycle arrest and apoptosis via inhibiting PTEN expression.

Inhibition of ER stress-related IRE1α/CREB/NLRP1 pathway promotes the apoptosis of human chronic myelogenous leukemia cell

Endoplasmic reticulum (ER) stress is induced in chronic myelogenous leukemia (CML) cells. As an important sensor of ER stress, inositol-requiring protein-1α (IRE1α) promotes the survival of acute myeloid leukemia. NLRP1 inflammasome activation promotes metastatic melanoma growth and that IRE1α can increase NLRP1 inflammasome gene expression. This study aimed to investigate the role and molecular mechanism of IRE1α in CML cell growth. We found that overexpression of IRE1α or NLRP1 significantly promoted the proliferation and decreased the apoptosis of CML cells, whereas downregulation of these two genes showed the opposite effects. 4-phenylbutyric acid (4-PBA), an ER stress inhibitor, reduced the expression of IRE1α and NLRP1. IRE1α elevated NLRP1 expression via cAMP responsive element binding protein (CREB) phosphorylation. NLRP1 inflammasome was activated in CML cells and its activation partly reversed ER stress inhibitor-induced cell apoptosis. Furthermore, inhibition of IRE1α/NLRP1 pathway sensitized CML cells to imatinib-mediated apoptosis. Additionally, IRE1α expression was elevated and NLRP1 inflammasome was activated in primary cells from CML patients. Downregulation of IRE1α or NLRP1 suppressed the proliferation and elevated the apoptosis of primary CML cells. Collectively, this study demonstrated that the IRE1α/CREB/NLRP1 pathway contributes to the progression of CML and the development of imatinib resistance. Hence, targeting ER stress-related IRE1α expression or NLRP1 inflammasome activation may block CML development.

Loss of Egr1, a human del5q gene, accelerates BCR-ABL driven chronic myelogenous leukemia.

There is substantial evidence that early growth response-1 (Egr1) gene, a zinc-finger transcription factor, behaves as a tumor suppressor in leukemia. This includes reports from this laboratory that constitutive Egr1 overrides leukemia conferred by deregulated c-Myc or E2F-1 in the M1 myeloid leukemic cell line by promoting differentiation. To investigate the effect of Egr1 on the initiation and progression of Chronic Myelogenous Leukemia (CML), lethally irradiated syngeneic wild type mice were reconstituted with bone marrow (BM) from either wild type or Egr1 null mice transduced with a 210-kD BCR-ABL-expressing MSCV-retrovirus (bone marrow transplantation {BMT}). Loss of Egr1 was observed to accelerate the development of BCR-ABL driven leukemia in recipient mice, resulting in the development of a more aggressive disease, a significantly shortened median survival time, and increased BCR-ABL expressing leukemic stem/progenitor cells (GFP+Lin-cKit+Sca+). Egr1 deficient progenitors expressing BCR-ABL exhibited decreased apoptosis, and increased cell viability and proliferation relative to WT counterparts. Secondary BMT of BCR-ABL BM revealed that loss of Egr1 resulted in enrichment of LSCs, consistent with shorter survival time and more aggressive disease of these mice compared to WT counterparts. Furthermore, serial re-plating colony assays indicated that loss of Egr1 increased self-renewal ability of BCR-ABL expressing BM. These novel findings on the tumor suppressor role of Egr1 in CML provide the impetus to study the effect of altering Egr1 expression in AML, where the overall five year survival rate remains low. The effect of loss of Egr1 in CML could reflect its established functions in normal hematopoiesis, maintaining quiescence of HSCs and driving terminal differentiation to the monocyte/macrophage lineage. Gain of function studies should validate these conclusions and provide further rationale for increased Egr1 as a therapeutic target in AML.

Expression of SHP-1 mRNA in Patients with Myelogenous Leukemia and Its Clinical Significance

To investigate the expression and clinical significance of SHP-1 mRNA in patients with myelogenous leukemia. The SYBR Green-based qRT-PCR was used to assess SHP-1 mRNA levels in 54 patients with chronic myelogenous leukemia (CML), 30 cases of de novo acute myelogenous leukemia (AML) and 10 persons without malignancy as controls. The relative expression levels of SHP-1 mRNA in control group (CG), chronic phase CML (CP-CML) group, advanced phase of CML (including accelerated phase CML and blastic phase CML) group and AML group were 1.15±0.62, 4.96±1.76, 2.60±0.90 and 0.45±0.20, respectively. The expression of SHP-1 mRNA in patients with CML significantly increased in comparison with that in CG(P<0.05). Meanwhile, the expression of SHP-1 mRNA in CP-CML group very significantly increased as compared with that in advanced stage of CML group(P<0.0001). The expression of SHP-1 mRNA in AML group significantly decreased as compared with that in CG group(P=0.0442). In CP-CML group, statistical analysis showed that SHP-1 mRNA expression at baseline in optimal responders (5.712±0.4476) was significantly higher than that in the suboptimal or failed responders (4.044±0.3701)(P=0.0090). Meanwhile, the SHP-1 mRNA expression in AML patients was higher than that in CR group (0.4984±0.05164) and non-CR group (0.3537±0.02388)(P=0.0017). The SHP-1 mRNA levels in CML patients are higher than that in AML patients, and probably correlats with disease progression of CML. The mRNA expression level of SHP-1 may be a molecular marker to predict early response to inatinib treatment in CP-CML and AML.

Activation of PPARγ by endogenous prostaglandin J2 mediates the antileukemic effect of selenium in murine leukemia

AbstractSupplementation with nontoxic doses of micronutrient selenium has been shown to alleviate chronic myelogenous leukemia (CML) via the elimination of leukemia stem cells (LSCs) in mice. This treatment provides a new and novel method for eliminating the LSCs that are otherwise not targeted by existing therapies. The antileukemic effect of selenium was dependent on the production of endogenous cyclopentenone prostaglandins (CyPGs), Δ-12 prostaglandin J2 (Δ12-PGJ2), and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2). Here, we show that these endogenous CyPGs, produced by mice maintained on selenium-supplemented diets, alleviate the symptoms of CML through their ability to activate the nuclear hormone receptor, peroxisome proliferator activated receptor γ (PPARγ). GW9662, a potent PPARγ antagonist, blocked the antileukemic effect of selenium supplementation by significantly reducing CyPGs. This effect was mediated by an increase in 15-prostaglandin dehydrogenase (15-Pgdh) activity, which oxidizes and inactivates Δ12-PGJ2 and 15d-PGJ2. In contrast, treatment with the PPARγ agonist pioglitazone mimicked selenium supplementation. This treatment led to decreased 15-Pgdh activity and increased CyPG levels, which inhibited CML progression. Selenium-dependent activation of PPARγ mediated by endogenous CyPGs decreased Stat5 expression leading to the downregulation of Cited2, a master regulator of LSC quiescence. These studies suggest a potential role for selenium supplementation as an adjuvant therapy in CML.