Inhibition of Xanthine Oxidoreductase Enhances the Potential of Tyrosine Kinase Inhibitors against Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is characterized by the expression of the oncogenic kinase BCR-ABL. Although tyrosine kinase inhibitors (TKIs) against BCR-ABL represent the standard therapeutic option for CML, resistances to TKIs can be a serious problem. Thus, the search for novel therapeutic approaches is still needed. CML cells show an increased ROS production, which is required for maintaining the BCR-ABL signaling cascade active. In line with that, reducing ROS levels could be an interesting therapeutic strategy for the clinical management of resistant CML. To analyze the therapeutic potential of xanthine oxidoreductase (XOR) in CML, we tested the effect of XOR inhibitor allopurinol. Here, we show for the first time the therapeutic potential of allopurinol against BCR-ABL-positive CML cells. Allopurinol reduces the proliferation and clonogenic ability of the CML model cell lines K562 and KCL22. More importantly, the combination of allopurinol with imatinib or nilotinib reduced cell proliferation in a synergistic manner. Moreover, the co-treatment arms hampered cell clonogenic capacity and induced cell death more strongly than each single-agent arm. The reduction of intracellular ROS levels and the attenuation of the BCR-ABL signaling cascade may explain these effects. Finally, the self-renewal potential of primary bone marrow cells from CML patients was also severely reduced especially by the combination of allopurinol with TKIs. In summary, here we show that XOR inhibition is an interesting therapeutic option for CML, which can enhance the effectiveness of the TKIs currently used in clinics.

Reconstitution of NK cells expressing KIR3DL1 is associated with reduced NK cell activity and relapse of CML after allogeneic hematopoietic stem cell transplantation

Although the prognosis of chronic myeloid leukemia (CML) in blastic crisis remains poor, some patients achieve long-term remission after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This may be attributable to graft-versus-leukemia (GVL) effects by donor lymphocytes, but their regulating mechanisms are unclear. Antitumor natural killer (NK) cell immunity is assumed to be important in CML, and we have previously shown that allelic polymorphisms of killer immunoglobulin-like receptors (KIRs) and histocompatibility leukocyte antigens (HLAs) are associated with the response of CML to tyrosine kinase inhibitors. Here, we report a case of CML in blastic phase who received HLA-matched but KIR3DL1 allelic-mismatched allo-HSCT. After transplant, decreased BCR-ABL transcript levels and enhanced NK cell activity were transiently observed. However, reconstitution of KIR3DL1-expressing NK cells occurred, which was associated with diminished NK cell activity and increased BCR-ABL. This case indicates the potential significance of KIR3DL1 in NK cell-mediated GVL activity following allo-HSCT. To the best of our knowledge, this is the first report to analyze the association between sequential KIR3DL1 expression and activity of NK cells after allo-HSCT. Selecting donors with KIR3DL1-null alleles may maintain competent GVL effects and provide improved outcomes in allo-HSCT for CML.

siRNA-mediated BCR-ABL silencing in primary chronic myeloid leukemia cells using lipopolymers

Despite development of effective tyrosine kinase inhibitors for treatment of chronic myeloid leukemia (CML), some patients do not effectively respond to the therapy and can display resistance in response to the drug therapy. To develop an alternative approach to CML therapy, we are exploring siRNA mediated silencing of the primary CML oncogene, BCR-ABL, by using non-viral (polymeric) delivery systems. In this study, a group of lipopolymers derived from low molecular PEIs substituted with linoleic acid (LA), α-linolenic acid (αLA) and cholesterol (Chol) was investigated for the first time for siRNA delivery to CML primary samples. The delivery efficiency in primary cells was equivalent to CML K562 cell line, and the lipopolymers gave effective internalization of siRNA depending on the nature of lipid substituent. The PEI-αLA (2.5 αLA/PEI), PEI-Chol (2.2 Chol/PEI), and PEI-LA (2.6 LA/PEI) lipopolymers used as BCR-ABL siRNA carriers (at 60 nM siRNA) reduced the BCR-ABL mRNA expression by 17% to 45%, and inhibited the formation of colonies by 24% to 41% in comparison with control siRNA in mononuclear cells. BCR-ABL siRNA treatment reduced the BCR-ABL mRNA expression by 50% in one of two CD34+ samples tested, and combination of BCR-ABL siRNA with imatinib (IM) treatment decreased the colony formation by 65% in one of two samples evaluated. The fact that no single polymer was universally effective in all patient samples may suggest patient-to-patient variability in terms of therapeutic responses to siRNA therapy. These results showed that a low dose of BCR-ABL siRNA could be used with lipopolymers to reduce BCR-ABL mRNA expression, CML cell survival and colony formation. This proof of principle study in CML primary cells can be applied to silencing of other therapeutic targets besides BCR-ABL and a study with larger patient samples is warranted for better identification of effective siRNA carriers.

Lack of association between functional polymorphism of DNA repair genes (XRCC1, XPD) and clinical response in Indian chronic myeloid leukemia patients

The resistance for the tyrosine kinase inhibitors in chronic myeloid leukemia (CML) occurs mainly due to BCR/ABL1 dependent and independent mechanisms. The defective DNA repair due to functional polymorphisms in DNA repair genes, might act as an etiological factor for leukemia progression. The study was carried out to understand the role of DNA repair genes (XRCC1, XPD) polymorphisms in Imatinib mesylate (IM) resistant CML patients. The study was carried out in total 87 CML patients (43 nonresponders-cases and 44 responders) who were treated with Imatinib. The treatment and follow-up was done according to European LeukemiaNet guidelines. The genotyping of selected SNPs were studied using RFLP and confirmed with Sanger sequencing (20%). The statistical analysis was performed using online tools (Socscistatistics and GraphPad InStat software). In our study no significant association was inferred between genotypes of DNA repair genes (XRCC1; rs1799782, rs25487, and XPD; rs13181) and complete cytogenetic response as well as molecular response. However there might be a possibility of association between XRCC1 Arg399Gln genotype AA/GA and cytogenetic response though it is statistically insignificant (p > 0.05). Though none of the genotypes of the DNA repair genes showed association with IM response, near association between XRCC1Arg399Gln genotype and cytogenetic response observed in our study. Hence, large sample size should be studied to establish the association of SNPs of DNA repair genes and IM response. Our study is a novel and important to explain the role of DNA repair genes polymorphisms in IM resistance.

Rearrangement of PDGFRβ gene in a patient with Ph-negative chronic myeloid leukemia t(5;12)(q33;p13) in imatinib mesylate treatment-free remission: a case report

Chronic myeloid leukemia (CML) is a hematologic malignancy, in which more than 95% of CML patients are discovered with the Philadelphia chromosome (Ph) or BCR-ABL rearrangement. Those patients mainly suffer from CML, associating with lack of tyrosine kinase activity and BCR-ABL fusion gene. Here, we reported a patient with Ph-negative CML t(5;12)(q33;p13), accompanying with a rare genetic fusion between the TEL and PDGFRβ genes. We identified a novel TEL-PDGFRβ rearrangement, joining TEL (exon 12) to PDGFRβ (exon 5), resulting in overexpression of PDGFRβ. A promising result was achieved, in which TEL-PDGFRβ fusion gene could not be effectively detected during imatinib treatment, demonstrating complete molecular biologic remission. Thus, multiple tyrosine kinase inhibitors are associated with Ph-negative CML t(5;12)(q33;p13) with TEL-PDGFRβ rearrangement.

Detecting the stable point of therapeutic effect of chronic myeloid leukemia based on dynamic network biomarkers

Background

Most researches of chronic myeloid leukemia (CML) are currently focused on the treatment methods, while there are relatively few researches on the progress of patients’ condition after drug treatment. Traditional biomarkers of disease can only distinguish normal state from disease state, and cannot recognize the pre-stable state after drug treatment.

Results

A therapeutic effect recognition strategy based on dynamic network biomarkers (DNB) is provided for CML patients’ gene expression data. With the DNB criteria, the DNB with 250 genes is selected and the therapeutic effect index (TEI) is constructed for the detection of individual disease. The pre-stable state before the disease condition becomes stable is 1 month. Through functional analysis for the DNB, some genes are confirmed as key genes to affect the progress of CML patients’ condition.

Conclusions

The results provide a certain theoretical direction and theoretical basis for medical personnel in the treatment of CML patients, and find new therapeutic targets in the future. The biomarkers of CML can help patients to be treated promptly and minimize drug resistance, treatment failure and relapse, which reduce the mortality of CML significantly.

Electronic supplementary material

The online version of this article (10.1186/s12859-019-2738-0) contains supplementary material, which is available to authorized users.

Analysis of major BCR-ABL1 mRNA by digital polymerase chain reaction is useful for prediction of international scale

BACKGROUND

Major BCR-ABL1 mRNA in patients with chronic myeloid leukemia (CML) has generally been analysed by real-time polymerase chain reaction (PCR). Application of the international scale (IS) for the quantification of major BCR-ABL1 mRNA has been recommended in several sets of guidelines, including those of the European LeukemiaNet. The aim of this study was to clarify the efficacy of digital PCR technology for the IS of BCR-ABL1 mRNA in the patients with CML by comparing with real-time PCR.

METHODS

The analysis of BCR-ABL1 mRNA was carried out by the Ipsogen^® BCR-ABL1 Mbcr IS-MMR DX Kit (Qiagen), and the QuantStudio 3D Digital PCR System (Thermo Fisher Scientific‎) using 20 peripheral blood samples obtained from the 9 patients with CML at Sapporo Medical University Hospital.

RESULTS

The correlation between the data obtained by digital PCR and by real-time PCR was really high at R = 0.96. The detection limit of digital PCR was up to 0.003% and was equal to IS with 0.01% or less in comparison with real-time PCR.

CONCLUSIONS

Digital PCR technology is promising for predicting the IS value with similar efficacy to real-time PCR and should be useful for simple monitoring of the effects of tyrosine kinase inhibitor (TKI) treatments.

Optimization of combination therapy for chronic myeloid leukemia with dosing constraints

In this work, we demonstrate a mathematical technique for optimizing combination regimens with constraints. We apply the technique to a mathematical model for treatment of patients with chronic myeloid leukemia. The in-host model includes leukemic cell and immune system dynamics during treatment with tyrosine kinase inhibitors and immunomodulatory compounds. The model is minimal (semi-mechanistic) with just enough detail that all relevant therapeutic effects can be represented. The regimens are optimized to yield the highest possible reduction in disease burden, taking into account dosing constraints and side effect risks due to drug exposure. We compare the following three types of regimens: (1) regimens that are restricted to certain discrete dose levels, which can only change every three months; (2) optimal regimens determined using optimal control; and (3) regimens that are piecewise-constant like the first type of regimen, but are obtained as approximations to the optimal control regimens. All three types of regimens result in similar outcomes, but the last one is easy to compute in addition to being clinically feasible.

microRNA-199a/b-5p enhance imatinib efficacy via repressing WNT2 signaling-mediated protective autophagy in imatinib-resistant chronic myeloid leukemia cells

Imatinib (IM) is a first-line therapeutic drug for chronic myeloid leukemia (CML), a hematological disease. Mutations in the BCR-ABL domain increase formation of IM resistance in CML. However, not all patients are BCR-ABL domain-mutant dependent. Investigating non-mutant mechanisms in the development of acquired IM resistance is a critical issue. We explored the mechanisms which influence IM efficacy and resistance in CML. Higher protective autophagy was identified in IM-resistant K562 (K562R) cells. Inhibition of autophagy by the inhibitors, chloroquine and 3-methyladenine, enhanced IM's efficacy in K562R cells. In addition, microRNA (miR)-199a/b-5p were downregulated in K562R cells compared to parent cells. Overexpression of miR-199a/b-5p reduced autophagy and induced cell apoptosis, resulting in enhanced IM's efficacy in K562R cells. Moreover, expression levels of the Wingless-type MMTV integration site family member 2 (WNT2), a positive regulator of autophagy, were significantly higher in K562R cells, and it was validated as a direct target gene of miR-199a/b-5p. Overexpressions of miR-199a/b-5p inhibited WNT2 downstream signaling. Furthermore, overexpression and knockdown of WNT2 influenced autophagy formation and CML drug sensitivity to IM. Overexpression of WNT2 could also reverse miR-199a/b-5p-enhanced IM efficacy in K562R cells. These results emphasized that miR-199a/b-5p inhibited autophagy via repressing WNT2 signaling and might provide novel therapeutic strategies for future IM-resistant CML therapy and drug development.

Targeting chronic myeloid leukemia stem cells: can transcriptional program be a druggable target for cancers?

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm resulting from acquisition of constitutively active BCR-ABL protein tyrosine kinase in a hematopoietic stem cell (HSC). Though tyrosine kinase inhibitors (TKIs) have changed a fatal disease into manageable disease, most patients cannot discontinue TKI treatment due to persistence of TKI-resistant leukemia stem cells (LSCs). Much effort has been made to find out factors or pathways specifically operating in LSCs to selectively target LSCs, with some promising results at least in preclinical models. In this article, we briefly review the role of Wnt/β-catenin signaling and its related factors in CML LSCs, especially focusing on Tcf1/Lef1 transcription factors, major effectors of Wnt/β-catenin pathway, of which transcriptional program have recently been shown to be targetable with prostaglandin E1.

Minimal Residual Disease Eradication in CML: Does It Really Matter?

BCR-ABL1 tyrosine kinase inhibitors (TKIs) have improved the prognosis of chronic phase chronic myeloid leukemia (CP-CML) to an extent that survival is largely determined by non-CML mortality. Monitoring for minimal residual disease by measuring BCR-ABL1 messenger RNA is a key component of CML management. CP-CML patients who achieve a stable deep molecular response may discontinue (TKIs) with an ~ 50% chance of entering treatment-free remission (TFR). So far discontinuation of TKIs has largely been limited to clinical trials, but is on the verge of becoming a part of wider clinical practice. Careful patient selection, dense molecular monitoring, and prompt reinstitution of treatment in the event of relapse are all vital to reproduce the same level of success. Much effort has been dedicated to identifying therapeutic strategies to eliminate CML stem cells and enable to TFR in more patients. Unfortunately, despite promising preclinical data, as yet, none of the various approaches have entered clinical practice.

Association between Altered Expression and Genetic Variations of Transforming Growth Factor β-Smad Pathway with Chronic Myeloid Leukemia

Background: Chronic myeloid leukemia (CML) is a hematological disorder caused by fusion of BCR and ABL genes. BCR-ABL dependent and independent pathways play equally important role in CML. TGFβ-Smad pathway, an important BCR -ABL independent pathway, has scarce data in CML. Present study investigate the association between TGFβ-Smad pathway and CML. Materials and Methods: Sixty-four CML patients and age matched healthy controls (n=63) were enrolled in this study. Patients were segregated into responder and resistant groups depending on their response to Imatinib mesylate (IM). TGFβ1 serum levels were evaluated by ELISA and transcript levels of TGFβ1 receptors, SMAD4 and SMAD7 were evaluated by Real-Time PCR. Sequencing of exons and exon-intron boundaries of study genes was performed using Next Generation Sequencing (NGS) in 20 CML patients. Statistical analysis was performed using SPSS version 16.0. Results:TGFβ1 serum levels were significantly elevated (p = 0.02) and TGFβR2 and SMAD4 were significantly down-regulated (p = 0.012 and p = 0.043 respectively) in the patients. c.69A>G in TGFβ1, c.1024+24G>A in TGFβR1 and g.46474746C>T in SMAD7 were the most important genetic variants observed with their presence in 10/20, 8/20 and 7/20 patients respectively. In addition, TGFβR1 transcript levels were reduced in CML patients with c.69A>G mutation. None of the genes differed significantly in terms of expression or genetic variants between responder and resistant patient groups. Conclusion: Our findings demonstrate the role of differential expression and genetic variants of TGFβ-Smad pathway in CML. Decreased TGFβR2 and SMAD4 levels observed in the present study may be responsible for reduced tumor suppressive effects of this pathway in CML.

Chronic Myeloid Leukemia (CML) Mouse Model in Translational Research

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by increased proliferation of granulocytic cells without the loss of their capability to differentiate. CML is a clonal disease, originated at the level of Hematopoietic Stem Cells with the Philadelphia chromosome resulting from a reciprocal translocation between the chromosomes 9 and 22t(9;22)-(q34;q11). This translocation produces a fusion gene known as BCR-ABL which acquires uncontrolled tyrosine kinase activity, constantly turning on its downstream signaling molecules/pathways, and promoting proliferation of leukemia cell through anti-apoptosis and acquisition of additional mutations. To evaluate the role of each critical downstream signaling molecule of BCR-ABL and test therapeutic drugs in vivo, it is important to use physiological mouse disease models. Here, we describe a mouse model of CML induced by BCR-ABL retrovirus (MSCV-BCR-ABL-GFP; MIG-BCR-ABL) and how to use this model in translational research.Moreover, to expand the application of this retrovirus induced CML model in a lot of conditional knockout mouse strain, we modified this vector to a triple gene coexpression vector in which we can co-express BCR-ABL, GFP, and a third gene which will be tested in different systems. To apply this triple gene system in conditional gene knockout strains, we can validate the CML development in the knockout mice and trace the leukemia cell following the GFP marker. In this protocol, we also describe how we utilize this triple gene system to prove the function of Pten as a tumor suppressor in leukemogenesis. Overall, this triple gene system expands our research spectrum in current conditional gene knockout strains and benefits our CML translational research.

Mechanisms of Resistance to ABL Kinase Inhibition in Chronic Myeloid Leukemia and the Development of Next Generation ABL Kinase Inhibitors

Chronic myeloid leukemia is increasingly viewed as a chronic illness; most patients have a life expectancy close to that of the general population. Despite progress made using BCR-ABL1 tyrosine kinase inhibitors (TKIs), drug resistance via BCR-ABL1-dependent and BCR-ABL1-independent mechanisms continues to be an issue. BCR-ABL1-dependent resistance is primarily mediated through oncoprotein kinase domain mutations and usually results in overt resistance to TKIs. However, BCR-ABL1-independent resistance in the setting of effective BCR-ABL1 inhibition is recognized as a major contributor to minimal residual disease. Efforts to eradicate persistent leukemic stem cells have focused on combination therapy.

CALR-positive myeloproliferative disorder in a patient with Ph-positive chronic myeloid leukemia in durable treatment-free remission: a case report

Current diagnostic criteria for Philadelphia-negative myeloproliferative neoplasia (MPN) have been redefined by the discovery of Janus kinase 2 (JAK2), myeloproliferative leukemia (MPL) and calreticulin (CALR) genetic alterations. Only few cases of coexistence of CALR-mutated MPN and Philadelphia-positive chronic myeloid leukemia (CML) have been described so far. Here we report the case of a patient with CML diagnosed in 2001, treated with imatinib and pegylated interferon (IFN) frontline. She reached complete molecular remission (CMR) and discontinued imatinib, maintaining treatment free remission. Due to persistent thrombocytosis, we repeated bone marrow (BM) analysis and diagnosed CARL-mutated essential thrombocythemia (ET). A CALR-positive clone was found to be present since 2001, and was unaffected by imatinib treatment, possibly representing a molecular abnormality arising at stem cell level.

Clonal chromosomal aberrations in Philadelphia negative cells such as monosomy 7 and trisomy 8 may persist for years with no impact on the long term outcome in patients with chronic myeloid leukemia

The appearance of clonal chromosomal aberrations in Philadelphia negative cells (CCA/Ph-) during the treatment of chronic myeloid leukemia (CML) was recently confirmed. Importance of these findings has not been clearly defined. We present data on the time of appearance, persistence, size of the CCA/Ph- clone in terms of drugs used and hematological, cytogenetic and molecular response rates. The focus was on the peripheral blood cytopenias and myelodysplastic changes in the bone marrow microscopic evaluation. In 5 out of 155 (3,2%) CML patients, the persistent presence (up to nine years) of CCA/Ph- was found (monosomy 7 and trisomy 8 in unrelated clones in two patients treated with tyrosine kinase inhibitors; trisomy 8 in two patients on imatinib; trisomy 21 in one patient on interferon alfa treatment). Aberrations were present in median 24% Ph- cells in 3-15 subsequent analyses at different cytogenetic and molecular response time points. No evident myelodysplastic changes nor transformation to MDS/AML occurred in patients with CCA/Ph-. All the patients achieved major molecular response (MMR). It seems that CCA/Ph- presence does not affect the long term outcome in patients with chronic myeloid leukemia. Further complex monitoring of the CML patients with CCA/Ph- is still needed.

Nrf-2/Gst-α mediated imatinib resistance through rapid 4-HNE clearance

The advent of imatinib mesylate (IM) has dramatically improved the outcome of patients with chronic myeloid leukemia, but drug resistance, particularly in advanced stage of disease, portents eventual relapse and progression. To identify the candidate molecule responsible for resistance during IM treatment, an IM-resistant K562 cell line was generated by culturing in gradually increasing dose of IM. The expression of Nrf-2 and its downstream target, Gst-α, were significantly induced in these cells. GST-α, in turn, mediated cell survival by maintaining intracellular low level of 4-HNE. Inhibition of Nrf-2 effectively reduced the expression of Gst-α, resulting in accumulation of 4-HNE and elevated sensitiveness to IM. Moreover, in IM-sensitive K562 cells enforced Gst-α expression strikingly protected cells from the insult of IM. Finally, we also examined the levels of Nrf-2 in clinical bone morrow samples. Nrf-2 and Gst-α were more abundant in bone morrow of CML patients compared with that of healthy donors. In addition, Nrf-2 and Gst-α were further up-regulated in samples of patients with weak response to IM. In conclusion, our study shows that rapid clearance of 4-HNE by Nrf-2/GST may represents a novel molecular basis of IM resistance in CML.

SH2 Domain-Based FRET Biosensor for Measuring BCR-ABL Activity in Living CML Cells

Fluorescent proteins (FPs) displaying distinct spectra have shed their light on a wide range of biological functions. Moreover, sophisticated biosensors engineered to contain single or multiple FPs, including Förster resonance energy transfer (FRET)-based biosensors, spatiotemporally reveal the molecular mechanisms underlying a variety of pathophysiological processes. However, their usefulness for applied life sciences has yet to be fully explored. Recently, our research group has begun to expand the potential of FPs from basic biological research to the clinic. Here, we describe a method to evaluate the responsiveness of leukemia cells from patients to tyrosine kinase inhibitors using a biosensor based on FP technology and the principle of FRET. Upon phosphorylation of the tyrosine residue of the biosensor, binding of the SH2 domain to phosphotyrosine induces conformational change of the biosensor and brings the donor and acceptor FPs into close proximity. Therefore, kinase activity and response to kinase inhibitors can be monitored by an increase and a decrease in FRET efficiency, respectively. As in basic research, this biosensor resolves hitherto arduous tasks and may provide innovative technological advances in clinical laboratory examinations. State-of-the-art detection devices that enable such innovation are also introduced.

CML Mouse Model Generated from Leukemia Stem Cells

Chronic myeloid leukemia (CML) is a myeloproliferative disorder with a high number of well-differentiated neutrophils in peripheral blood and myeloid cells in bone marrow (BM). CML is derived from the hematopoietic stem cells (HSCs) with the Philadelphia chromosome (Ph(+), t(9;22)-(q34;q11)), resulting in generating a fusion oncogene, BCR/ABL1. HSCs with Ph(+) are defined as leukemia stem cells (LSCs), a subpopulation cell at the apex of hierarchies in leukemia cells and responsible for the disease continuous propagation. Several kinds of CML models have been developed to reveal the mechanism of CML pathogenesis and evaluate therapeutic drugs in the past three decades. Here, we describe the procedures to generate a CML mouse model by introducing BCR/ABL1 into Lin(-)Sca1(+) cKit(+) population cells purified from mouse bone marrow. In CML retroviral transduction/transplantation mouse models, this modified model can mimic CML pathogenesis on high fidelity.

Discovering gene expression signatures responding to tyrosine kinase inhibitor treatment in chronic myeloid leukemia

BACKGROUND

Tyrosine kinase inhibitor (TKI)-based therapy is a recommended treatment for patients with chronic myeloid leukemia (CML). However, a considerable group of CML patients do not respond well to the TKI therapy. Challenging to overcome this problem, we tried to discover molecular signatures in gene expression profiles to discriminate the responders and non-responders of TKI therapy.

METHODS

We collected three microarray datasets of CML patients having total 73 responders and 38 non-responders. Statistical analysis was performed to identify differentially expressed genes (DEGs) as gene signature candidates from integrated microarray datasets. The classification performance of these genes and further selected discriminator gene sets was tested by using random forest and iterative backward variable selection methods.

RESULTS

We identified a set of genes including CTBP2, NADK, AZU1, CTSH, FSTL1, and HDLBP showing the highest accuracy more than 69.44 % to classify TKI response in CML patients. Interestingly, four genes of them are on the signaling pathway of cell proliferation. This set of genes showed much higher performance than the average performance of other genes in downstream signaling of TKI target, BCR-ABL.

CONCLUSIONS

In this study, we could find a set of potential companion diagnostic markers for TKI treatment and, at the same time, the potential of gene expression analysis to enhance the coverage of companion diagnostics.

MicroRNA-130a regulates cell malignancy by targeting RECK in chronic myeloid leukemia

Emerging evidence has indicated that microRNAs are involved in tumor development and progression, acting as either tumor suppressors or oncogenes. In this study, we aimed to investigate the role of miR-130a in the pathogenesis of chronic myeloid leukemia (CML). Functional studies indicate that over-expression of miR-130a in A562 CML cells dramatically suppresses cell proliferation and induces cell apoptosis both in vitro and in vivo. Furthermore, we demonstrate that the transcriptional regulator RECK is a target of miR-130a. In conclusion, our study suggests that miR-130a may function as a novel tumor suppressor in CML, and its anti-oncogenic activity may involve the direct targeting and inhibition of RECK.

New Mouse Models to Investigate the Efficacy of Drug Combinations in Human Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) comprises a simple and effective paradigm for generating new insights into the cellular origin, pathogenesis, and treatment of many types of human cancer. In particular, mouse models of CML have greatly facilitated the understanding of the underlying molecular mechanisms and pathogenesis of this disease and have led to the identification of new drug targets that in some cases offer the possibility of functional cure. There are currently three established CML mouse models: the BCR-ABL transgenic model, the BCR-ABL retroviral transduction/transplantation model, and the xenotransplant immunodeficient model. Each has its own unique advantages and disadvantages. Depending on the question of interest, some models may be more appropriate than others. In this chapter, we describe a newly developed xenotransplant mouse model to determine the efficacy of novel therapeutic agents, either alone or in combination. The model facilitates the evaluation of the frequency of leukemic stem cells with long-term leukemia-initiating activity, a critical subcellular population that causes disease relapse and progression, through the utilization of primary CD34(+) CML stem/progenitor cells obtained from CML patients at diagnosis and prior to drug treatment. We have also investigated the effectiveness of new combination treatment strategies designed to prevent the development of leukemia in vivo using BCR-ABL (+) blast crisis cells as a model system. These types of in vivo studies are important for the prediction of individual patient responses to drug therapy, and have the potential to facilitate the design of personalized combination therapy strategies.

Molecular biological characteristics of the recruitment of hematopoietic stem cells from bone marrow niche in chronic myeloid leukemia

Chronic myeloid leukemia (CML) can be contextualized as a disease of unregulated self-renewal of stem cells which exist in a quiescent state and are instructed to differentiate and mobilize to circulation under pathologic circumstances leading to tumor invasion and metastasis. Here we found that matrix metalloproteinase-9 (MMP-9), induced by TGF-β1, upregulated s-KitL and s-ICAM-1, permitting the transfer of c-kit(+) hematopoietic stem cells (HSCs) from the quiescent to proliferative niche in CML. Further study showed that this MMP-9 production was raised by CML specific BCR/ABL(+) oncogene mediated TGF-β1. Besides, phosphatidylinositol-3 kinase (PI3K)/Akt/nuclear factor (NF)-κB signaling pathway was evidenced to govern this stem cell recruitment in CML pathogenesis. Overall, our observations defined a novel critical role for TGF-β1 induced PI3K/Akt/NF-κB signaling pathway in the recruitment of the malignant cells in CML by releasing s-KitL and s-ICAM-1 and this was through a distinct PI3K/Akt/NF-κB signaling pathway.

Preclinical model for identification of therapeutic targets for CML offers clues for handling imatinib resistance

Success of imatinib in chronic myeloid leukemia (CML) therapy has undoubtedly proved utility of signalling molecules as therapeutic targets. However, development of imatinib resistance and progression to blastic crisis are the current challenges in clinics. To develop therapeutic alternatives for CML, understanding of signalling events downstream of bcr-abl might be helpful. Current CML cell lines do not give comprehensive picture of signalling events involved in pathogenesis of CML. Hence, there is a major unmet need for a better preclinical model for CML. Here, we report on development of RIN9815/bcr-abl, a novel cell line model that mimics signalling events in CML PMNL. Studies on crucial signalling molecules i.e., ras, rac, rhoA and actin in this cell line identified rhoA as the key regulator involved in CML cell function as well as proliferation of both, imatinib sensitive and resistant cells. Hence, RIN9815/bcr-abl could serve as the unique preclinical model in understanding pathogenesis of CML and in drug development.

Celecoxib sensitizes imatinib-resistant K562 cells to imatinib by inhibiting MRP1-5, ABCA2 and ABCG2 transporters via Wnt and Ras signaling pathways

Imatinib mesylate, a tyrosine kinase inhibitor, is very effective in the treatment of chronic myeloid leukemia (CML). However, development of resistance to imatinib therapy is also a very common mechanism observed with long-term administration of the drug. Our previous studies have highlighted the role of cyclooxygenase-2 (COX-2) in regulating the expression of multidrug resistant protein-1 (MDR1), P-gp, in imatinib-resistant K562 cells (IR-K562) via PGE2-cAMP-PKC-NF-κB pathway and inhibition of COX-2 by celecoxib, a COX-2 specific inhibitor, inhibits this pathway and reverses the drug resistance. Studies have identified that not only MDR1 but other ATP-binding cassette transport proteins (ABC transporters) are involved in the development of imatinib resistance. Here, we tried to study the role of COX-2 in the regulation of other ABC transporters such as MRP1, MRP2, MRP3, ABCA2 and ABCG2 that have been already implicated in imatinib resistance development. The results of the study clearly indicated that overexpression of COX-2 lead to upregulation of MRP family proteins in IR-K562 cells and celecoxib down-regulated the ABC transporters through Wnt and MEK signaling pathways. The study signifies that celecoxib in combination with the imatinib can be a good alternate treatment strategy for the reversal of imatinib resistance.