Molecular biology of bcr-abl1-positive chronic myeloid leukemia

Chronic myeloid leukemia with a significant increase of monocytes and rare karyotype: A case report and literature review

Chronic myeloid leukemia with a significant increase of monocytes is rare and difficult to identify from chronic myelo-monocytic leukemia in clinic. A 31-year-old male patient with systemic pain was initially diagnosed as chronic myelo-monocytic leukemia, who was finally diagnosed as chronic myeloid leukemia by fusion gene and chromosome examination. In addition to the typical Ph chromosome, a rare chromosome translocation t(2; 7)(p13; p22) was observed. The detection of monocyte subsets by multi-parameter flow cytometry is a diagnostic marker to distinguish the above 2 diseases. The relationship between fusion genes and mononucleosis is not clear. Tyrosine kinase inhibitors or allogeneic hematopoietic stem cell transplantation can be used in the treatment for this disease.

Gene Transactivation and Transrepression in MYC-Driven Cancers

MYC is a proto-oncogene regulating a large number of genes involved in a plethora of cellular functions. Its deregulation results in activation of MYC gene expression and/or an increase in MYC protein stability. MYC overexpression is a hallmark of malignant growth, inducing self-renewal of stem cells and blocking senescence and cell differentiation. This review summarizes the latest advances in our understanding of MYC-mediated molecular mechanisms responsible for its oncogenic activity. Several recent findings indicate that MYC is a regulator of cancer genome and epigenome: MYC modulates expression of target genes in a site-specific manner, by recruiting chromatin remodeling co-factors at promoter regions, and at genome-wide level, by regulating the expression of several epigenetic modifiers that alter the entire chromatin structure. We also discuss novel emerging therapeutic strategies based on both direct modulation of MYC and its epigenetic cofactors.

Assessment of individual molecular response in chronic myeloid leukemia patients with atypical BCR-ABL1 fusion transcripts: recommendations by the EUTOS cooperative network

Purpose

Approximately 1–2% of chronic myeloid leukemia (CML) patients harbor atypical BCR-ABL1 transcripts that cannot be monitored by real-time quantitative PCR (RT-qPCR) using standard methodologies. Within the European Treatment and Outcome Study (EUTOS) for CML we established and validated robust RT-qPCR methods for these patients.

Methods

BCR-ABL1 transcripts were amplified and sequenced to characterize the underlying fusion. Residual disease monitoring was carried out by RT-qPCR with specific primers and probes using serial dilutions of appropriate BCR-ABL1 and GUSB plasmid DNA calibrators. Results were expressed as log reduction of the BCR-ABL1/GUSB ratio relative to the patient-specific baseline value and evaluated as an individual molecular response (IMR).

Results

In total, 330 blood samples (2–34 per patient, median 8) from 33 CML patients (19 male, median age 62 years) were analyzed. Patients expressed seven different atypical BCR-ABL1 transcripts (e1a2, n = 6; e6a2, n = 1; e8a2, n = 2; e13a3, n = 4; e14a3, n = 6; e13a3/e14a3, n = 2; e19a2, n = 12). Most patients (61%) responded well to TKI therapy and achieved an IMR of at least one log reduction 3 months after diagnosis. Four patients relapsed with a significant increase of BCR-ABL1/GUSB ratios.

Conclusions

Characterization of atypical BCR-ABL1 transcripts is essential for adequate patient monitoring and to avoid false-negative results. The results cannot be expressed on the International Scale (IS) and thus the common molecular milestones and guidelines for treatment are difficult to apply. We, therefore, suggest reporting IMR levels in these cases as a time-dependent log reduction of BCR-ABL1 transcript levels compared to baseline prior to therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03569-8.

Development of BCR-ABL1 Transgenic Zebrafish Model Reproducing Chronic Myeloid Leukemia (CML) Like-Disease and Providing a New Insight into CML Mechanisms

Zebrafish has proven to be a versatile and reliable experimental in vivo tool to study human hematopoiesis and model hematological malignancies. Transgenic technologies enable the generation of specific leukemia types by the expression of human oncogenes under specific promoters. Using this technology, a variety of myeloid and lymphoid malignancies zebrafish models have been described. Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasia characterized by the BCR-ABL1 fusion gene, derived from the t (9;22) translocation causing the Philadelphia Chromosome (Ph). The BCR-ABL1 protein is a constitutively activated tyrosine kinas inducing the leukemogenesis and resulting in an accumulation of immature leukemic cells into bone marrow and peripheral blood. To model Ph+ CML, a transgenic zebrafish line expressing the human BCR-ABL1 was generated by the Gal4/UAS system, and then crossed with the hsp70-Gal4 transgenic line. The new line named (BCR-ABL1pUAS:CFP/hsp70-Gal4), presented altered expression of hematopoietic markers during embryonic development compared to controls and transgenic larvae showed proliferating hematopoietic cells in the caudal hematopoietic tissue (CHT). The present transgenic zebrafish would be a robust CML model and a high-throughput drug screening tool.

Definition, Epidemiology, Pathophysiology, and Essential Criteria for Diagnosis of Pediatric Chronic Myeloid Leukemia

Simple Summary

The low incidence (1:1,000,000) of chronic myeloid leukemia (CML) in the first two decades of life presents an obstacle to accumulation of pediatric experience and knowledge on this leukemia. Biological features of CML are shared but also differing between adult and pediatric patients. This review aims; (i) to define the disease based on an unified terminology, (ii) to list the diseases to be considered as a differential diagnosis in children, (iii) to outlines the morphological, histopathological and immuno-phenotypical findings of pediatric CML, (iv) to illustrate rare but classical complications resulting from high white cell and platelet counts at diagnosis, and (v) to recommend a uniform approach for the diagnostic procedures to be applied. Evidently, only a clear detailed picture of all relevant features can lay the basis for standardized treatment approaches.

Abstract

Depending on the analytical tool applied, the hallmarks of chronic myeloid leukemia (CML) are the Philadelphia Chromosome and the resulting mRNA fusion transcript BCR-ABL1. With an incidence of 1 per 1 million of children this malignancy is very rare in the first 20 years of life. This article aims to; (i) define the disease based on the WHO nomenclature, the appropriate ICD 11 code and to unify the terminology, (ii) delineate features of epidemiology, etiology, and pathophysiology that are shared, but also differing between adult and pediatric patients with CML, (iii) give a short summary on the diseases to be considered as a differential diagnosis of pediatric CML, (iv) to describe the morphological, histopathological and immunophenotypical findings of CML in pediatric patients, (v) illustrate rare but classical complications resulting from rheological problems observed at diagnosis, (vi) list essential and desirable diagnostic criteria, which hopefully in the future will help to unify the attempts when approaching this rare pediatric malignancy.

The prognostic importance of BCR-ABL transcripts in Chronic Myeloid Leukemia: A systematic review and meta-analysis

BACKGROUND

Chronic Myeloid Leukemia (CML) is characterized by the overproduction of BCR-ABL, a tyrosine kinase with constitutive activity, in which the majority of CML patients have e13a2 or e14a2 transcripts. Reckoned the possible associations between the hematologic and molecular features of the disease, a profound understanding of different aspects of this neoplasm would be provided.

METHOD

The authors implemented a systematic literature search, utilizing the terms published articles or internationally accepted abstracts from PubMed, Embase, Medline, Cochrane library before January 2019. Weighted mean proportion and 95 % confidence intervals (CIs) of CML prevalence calculated using a fixed-effects and a random-effects model. Statistical heterogeneity was evaluated using the I2 statistic.

RESULTS

34 studies for a total of 54,034 Patients were selected and included in the review. Results revealed that compared to e13a2 group, the overall estimated prevalence is much higher in the e14a2 (39 % and 54 %, respectively). Besides, the overall estimated prevalence ratio of male to female was higher in the e13a2 group in comparison to e14a2 (1.08 and 0.856 respectively). The overall estimated prevalence of dual transcription of e13a2/e14a2 was 1.11 %, and male/female overall estimated prevalence ratio was 1.18.

CONCLUSION

This meta-analysis of CML patients demonstrated the e14a2 as the more common transcript type. Usually, the e14a2 transcript is prevalent in females, whereas e13a2 and dual transcription of e13a2/e14a2 are more common in men. These data explicate that the differences in proportion are not by chance. This is crucial, as the transcript type is a variable suspected to be of prognostic importance for the treatment-related response, the outcome of treatment, and the rate of treatment-free remission.

Genetic Screening for Potential New Targets in Chronic Myeloid Leukemia Based on Drosophila Transgenic for Human BCR-ABL1

Chronic myeloid leukemia is a myeloproliferative neoplasm characterized by the presence of the Philadelphia chromosome that originates from the reciprocal translocation t(9;22)(q34;q11.2) and encodes for the constitutively active tyrosine kinase protein BCR-ABL1 from the Breakpoint Cluster Region (BCR) sequence and the Abelson (ABL1) gene. Despite BCR-ABL1 being one of the most studied oncogenic proteins, some molecular mechanisms remain enigmatic, and several of the proteins, acting either as positive or negative BCR-ABL1 regulators, are still unknown. The Drosophila melanogaster represents a powerful tool for genetic investigations and a promising model to study the BCR-ABL1 signaling pathway. To identify new components involved in BCR-ABL1 transforming activity, we conducted an extensive genetic screening using different Drosophila mutant strains carrying specific small deletions within the chromosomes 2 and 3 and the gmrGal4,UAS-BCR-ABL1 4M/TM3 transgenic Drosophila as the background. From the screening, we identified several putative candidate genes that may be involved either in sustaining chronic myeloid leukemia (CML) or in its progression. We also identified, for the first time, a tight connection between the BCR-ABL1 protein and Rab family members, and this correlation was also validated in CML patients. In conclusion, our data identified many genes that, by interacting with BCR-ABL1, regulate several important biological pathways and could promote disease onset and progression.

Nanomedicine of tyrosine kinase inhibitors

Recent progress in nanomedicine and targeted therapy brings new breeze into the field of therapeutic applications of tyrosine kinase inhibitors (TKIs). These drugs are known for many side effects due to non-targeted mechanism of action that negatively impact quality of patients' lives or that are responsible for failure of the drugs in clinical trials. Some nanocarrier properties provide improvement of drug efficacy, reduce the incidence of adverse events, enhance drug bioavailability, helps to overcome the blood-brain barrier, increase drug stability or allow for specific delivery of TKIs to the diseased cells. Moreover, nanotechnology can bring new perspectives into combination therapy, which can be highly efficient in connection with TKIs. Lastly, nanotechnology in combination with TKIs can be utilized in the field of theranostics, i.e. for simultaneous therapeutic and diagnostic purposes. The review provides a comprehensive overview of advantages and future prospects of conjunction of nanotransporters with TKIs as a highly promising approach to anticancer therapy.

Circulating miR-146a expression predicts early treatment response to imatinib in adult chronic myeloid leukemia

This study aimed to investigate the prognostic role of circulating miR-146a in the prediction of early response to imatinib treatment in patients with chronic myeloid leukemia (CML). Sixty patients with CML and 20 healthy controls were recruited in this study. BCR-ABL was assessed by quantitative rt-PCR at days 0 and 90 of imatinib therapy. Circulating miR-146a levels were assessed by quantitative rt-PCR at days 0, 14 and 90 of imatinib therapy for patients and once for controls. At day 90 of treatment, treatment response was achieved in 48 patients (80.0%). Responders had significantly lower baseline Sokal score when compared with non-responders. They also had significantly lower BCR-ABL expression at day 90 of treatment. The circulating miR-146a level was significantly lower in patients with CML than in healthy subjects and showed a significant rise after 14 days of imatinib treatment and an inverse correlation with BCR-ABL expression levels at 90 days. Using multivariate logistic regression analysis, baseline BCR-ABL (%) (OR (95% CI) 1.09 (1.03 to 1.016), p=0.006) and miR-146a at 14 days (OR (95% CI) 0.002 (0.0 to 0.09), p=0.001) were significant predictors of treatment response. Using ROC curve analysis, it was found that miR-146a expression at 14 and 90 days could distinguish responders from non-responders (AUC (95% CI) 0.849 (0.733 to 0.928) and 0.867 (0.755 to 0.941), respectively). This study reported for the first time that measurement of the circulating miR-146a expression at 14 days can predict the early response to imatinib treatment in patients with CML. Thus, this work indicates that miR-146a should be investigated in the setting of treatment response to other tyrosine kinase inhibitors.

Distribution of BCR-ABL1 Transcript Variants in Nigerians with Chronic Myeloid Leukemia

The distribution of BCR-ABL1 transcript variants e13a2 ("b2a2") and e14a2 ("b3a2") in Nigerians with chronic myeloid leukemia (CML) had not been previously studied. In addition, there is paucity of data on the impact of BCR-ABL1 transcript variants on clinical presentation and survival in CML patients in Nigeria. The BCR-ABL1 transcript variants were analyzed in 230 Imatinib-treated CML patients at diagnosis. Patients with incomplete data (n = 28), e19a2 (n = 3) and e1a2 (n = 1) were excluded from analysis of transcript variant on disease presentation and survival leaving only 198. The frequencies of BCR-ABL1 transcript variants were 30 (13.0%), 114 (49.6%), 82 (35.7%), three (1.3%) and one (0.4%) for e13a2, e14a2, co-expression of e13a2/e14a2, e19a2 and e1a2, respectively. A significantly higher platelet count was found in patients with e13a2 variant (531.1 ± 563.4 × 10⁹/L) than in those expressing e14a2 (488.2 ± 560.3 × 10⁹/L) or e13a2/e14a2 (320.7 ± 215.8 × 10⁹/L); p = 0.03. No significant differences were found between the variants with regards to gender, age, phase of disease at diagnosis, total white blood cell count, neutrophil percentage, hematocrit, splenomegaly or hepatomegaly. Overall survival was higher but not statistically significant (p = 0.4) in patients with e14a2 variant (134 months) than in e13a2 (119 months) and co-expression of e13a2/e14a2 (115 months). Nigerian CML patients have the highest incidence of co-expression of e13a2 and e14a2. Distinct disease characteristics which contrast with findings from the Western countries were also identified in Nigerians which may be due to genetic factors.

Epigenetic Mechanisms in Canine Cancer

A plethora of data has highlighted the role of epigenetics in the development of cancer. Initiation and progression of different cancer types are associated with a variety of changes of epigenetic mechanisms, including aberrant DNA methylation, histone modifications, and miRNA expression. At the same time, advances in the available epigenetic tools allow to investigate and reverse these epigenetic changes and form the basis for the development of anticancer drugs in human oncology. Although human and canine cancer shares several common features, only recently that studies emerged investigating the epigenetic landscape in canine cancer and applying epigenetic modulators to canine cancer. This review focuses on the existing studies involving epigenetic changes in different types of canine cancer and the use of small-molecule inhibitors in canine cancer cells.

Prognostic Significance of Transcript-Type BCR - ABL1 in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is characterized by the presence of the BCR-ABL1 fusion gene. In more than 95% of CML patients, the typical BCR-ABL1 transcript subtypes are e13a2 (b2a2), e14a2 (b3a2), or the simultaneous expression of both. Other less frequent transcript subtypes, such as e1a2, e2a2, e6a2, e19a2, e1a3, e13a3, and e14a3, have been sporadically reported. The main purpose of this review is to assess the possible impact of different transcripts on the response rate to tyrosine kinase inhibitors (TKIs), the achievement of stable deep molecular responses (s-DMR), the potential maintenance of treatment-free remission (TFR), and long-term outcome of CML patients treated with TKIs. According to the majority of published studies, patients with e13a2 transcript treated with imatinib have lower and slower cytogenetic and molecular responses than those with e14a2 transcript. They should be considered a high-risk group that would most benefit from frontline treatment with second-generation TKIs (2GTIKIs). Although few studies have been published, similar significant differences in response rates to 2GTKIs have been not reported. The e14a2 transcript seems to be a favorable prognostic factor for obtaining s-DMR, irrespective of the TKI received, and is also associated with a very high rate of TFR maintenance. Indeed, patients with e13a2 transcript achieve a lower rate of s-DMR and experience a higher probability of TFR failure. According to most reported data in the literature, the type of transcript does not seem to affect long-term outcomes of CML patients treated with TKIs. In TFR, the e14a2 transcript appears to be related to favorable responses. 2GTKIs as frontline therapy might be a convenient approach in patients with e13a2 transcript to achieve optimal long-term outcomes.

Investigation of the Mechanism of Shengmai Injection on Sepsis by Network Pharmacology Approaches

Shengmai injection (SMI) contains Ginsen Radix et Rhizoma Rubra, Ophiopogon japonicus, and Schisandrae Chinensis Fructus. It is used as a supportive herbal medicine in the management of sepsis, systemic inflammatory response syndrome, and septic or hemorrhagic shock. An UPLC method was established to identify and evaluate SMI fingerprints. Fingerprint similarities of 9 batches of SMI were compared. The network platform, “TCM-components-core targets-key pathways,” was established, and the mechanism of SMI in the treatment of sepsis was investigated. The similarity of 9 batches of SMI fingerprints was greater than 0.91. 44 peaks were selected as the common peaks, of which 11 peaks were identified. KEGG functional pathway analysis showed SMI was mainly involved in the pathways of cancer, cell cycle, and p53 signaling, suggesting SMI protects multiple organs via regulating immunity, inflammation, apoptosis, and energy metabolism. GO enrichment analysis showed active SMI components regulated various biological processes and altered the pathophysiology of sepsis. The interplays between SMI and multiple energy metabolism signaling cascades confer protection from life-threatening multiple organ failure in sepsis.

The Hidden Pathogenesis of CML: Is BCR-ABL1 the First Event?

PURPOSE OF REVIEW

Identification of the BCR-ABL1 fusion oncogene in patients diagnosed with chronic myeloid leukemia (CML) led to the development of targeted therapy responsible for the dramatic survival benefits observed in the past two decades. However, despite these revolutionary findings, there remains marked disparity in patient outcomes. Why do some patients present de novo while others evolve to the more aggressive stages of CML? Why can select patients successfully discontinue therapy as part of a treatment-free remission attempt whereas others fail to meet specific molecular milestones?

RECENT FINDINGS

BCR-ABL1 kinase mutations are only identified in approximately 50% of patients with poor responses and disease progression, suggesting the presence of alternative resistance mechanisms. Numerous institutions have identified the presence of additional genomic events in addition to BCR-ABL1 with the increasing availability of next-generation sequencing. We explore the potential pathways and events that may cooperate with BCR-ABL1 to answer these questions but also challenge the fundamental tenet that BCR-ABL1 is always the sole event initiating CML.

Chronic myeloid leukemia presenting in lymphoblastic crisis, a differential diagnosis with Philadelphia-positive B-lymphoblastic leukemia

Rare patients with chronic myeloid leukemia (CML) can present initially in lymphoblastic crisis (LBC) mimicking Ph + B-lymphoblastic leukemia (B-ALL). We retrospectively reviewed 275 adults who diagnosed initially as Ph + B-ALL and identified 28 patients with at least one of three features supporting the diagnosis of CML-LBC: 1) a large discrepancy between the blast count and Ph + clone; 2) Ph + clone persistent when B-ALL in remission; 3) BCR/ABL1 fusion detected in segmented cells. BCR-ABL1 fusions were p210 in 25 patients and p190 in 3 patients. In comparison to patients with Ph + B-ALL, patients with CML-LBC were older; had higher leukocyte and absolute neutrophil counts; higher immature myeloid cells in peripheral blood; lower blast counts; and inferior outcomes. In addition, we prospectively analyzed 26 patients with Ph + B-lymphoblastic leukemia and identified 8 patients with features more consistent with CML-LBC. These findings highlight the importance of distinguishing CML-LBC from de novo Ph + B-ALL.

Challenges and Opportunities in Cancer Drug Resistance

There has been huge progress in the discovery of targeted cancer therapies in recent years. However, even for the most successful and impactful cancer drugs which have been approved, both innate and acquired mechanisms of resistance are commonplace. These emerging mechanisms of resistance have been studied intensively, which has enabled drug discovery scientists to learn how it may be possible to overcome such resistance in subsequent generations of treatments. In some cases, novel drug candidates have been able to supersede previously approved agents; in other cases they have been used sequentially or in combinations with existing treatments. This review summarizes the current field in terms of the challenges and opportunities that cancer resistance presents to drug discovery scientists, with a focus on small molecule therapeutics. As part of this review, common themes and approaches have been identified which have been utilized to successfully target emerging mechanisms of resistance. This includes the increase in target potency and selectivity, alternative chemical scaffolds, change of mechanism of action (covalents, PROTACs), increases in blood-brain barrier permeability (BBBP), and the targeting of allosteric pockets. Finally, wider approaches are covered such as monoclonal antibodies (mAbs), bispecific antibodies, antibody drug conjugates (ADCs), and combination therapies.

Signal-transducing adapter protein-1 is required for maintenance of leukemic stem cells in CML

The family of signal-transducing adapter proteins (STAPs) has been reported to be involved in a variety of intracellular signaling pathways and implicated as transcriptional factors. We previously cloned STAP-2 as a c-Fms interacting protein and explored its effects on chronic myeloid leukemia (CML) leukemogenesis. STAP-2 binds to BCR-ABL, upregulates BCR-ABL phosphorylation, and activates its downstream molecules. In this study, we evaluated the role of STAP-1, another member of the STAP family, in CML pathogenesis. We found that the expression of STAP-1 is aberrantly upregulated in CML stem cells (LSCs) in patients’ bone marrow. Using experimental model mice, deletion of STAP-1 prolonged the survival of CML mice with inducing apoptosis of LSCs. The impaired phosphorylation status of STAT5 by STAP-1 ablation leads to downregulation of antiapoptotic genes, Bcl-2 and Bcl-xL. Interestingly, transcriptome analyses indicated that STAP-1 affects several signaling pathways related to BCR-ABL, JAK2, and PPARγ. This adapter protein directly binds to not only BCR-ABL, but also STAT5 proteins, showing synergistic effects of STAP-1 inhibition and BCR-ABL or JAK2 tyrosine kinase inhibition. Our results identified STAP-1 as a regulator of CML LSCs and suggested it to be a potential therapeutic target for CML.

A Comprehensive Review of Clinical Cardiotoxicity Incidence of FDA-Approved Small-Molecule Kinase Inhibitors

Numerous protein kinases encoded in the genome have become attractive targets for the treatment of different types of cancer. As of January 2020, a total of 52 small-molecule kinase inhibitors (SMKIs) have been approved by the FDA. With the numerous clinical trials and a heavy focus on drug safety, SMKI-induced cardiotoxicity, which is a life-threatening risk, has greatly attracted the attention of researchers. In this review, the SMKIs with cardiotoxicity incidence were described exhaustively. The data were collected from 42 clinical trials, 25 FDA-published documents, seven meta-analysis/systematic reviews, three case reports and more than 50 other types of articles. To date, 73% (38 of 52) of SMKIs have reported treatment-related cardiotoxicity. Among the 38 SMKIs with known cardiotoxicity, the rates of incidence of cardiac adverse events were QT prolongation: 47% (18 of 38), hypertension: 40% (15 of 38), left ventricular dysfunction: 34% (13 of 38), arrhythmia: 34% (13 of 38), heart failure: 26% (10 of 38) and ischemia or myocardial infarction: 29% (11 of 38). In the development process of novel SMKIs, more attention should be paid to balancing the treatment efficacy and the risk of cardiotoxicity. In preclinical drug studies, producing an accurate and reliable cardiotoxicity evaluation model is of key importance. To avoid the clinical potential cardiotoxicity risk and discontinuation of a highly effective drug, patients treated with SMKIs should be proactively monitored on the basis of a global standard. Moreover, the underlying mechanisms of SMKI-induced cardiotoxicity need to be further studied to develop new therapies for SMKI-induced cardiotoxicity.

Chronic Myeloid Leukemia in Children: Challenges and Opportunities : Based on 7th Dr. I. C. Verma Excellence Award for Young Pediatricians Delivered as Oration on 29th Sept. 2019

Treatment with tyrosine kinase inhibitors (TKI) is an effective therapy for children and adolescents with chronic phase of chronic myeloid leukemia (CML). For the majority of patients with CML in low- and middle-income countries (LMIC), imatinib is the TKI of choice for reasons of cost, availability, and experience. Children are exposed to therapy for a greater proportion of their lifetime as compared to adults. The adverse effects of prolonged administration of TKI is a subject of ongoing research, as more experience is collected. Therapy with TKI is currently considered to be life-long. Trials on stopping treatment are ongoing to explore if it may be feasible in selected patients, as reported in adults. Growth-failure is a concerning adverse effect. Currently, it seems unclear if the final height attained is within the expected range of the mid-parenteral height and growth standards. Whether the children will achieve a normal height at the end of their growth potential or remain below the predicted range is critical to decide if therapeutic interventions (E.g., growth hormone therapy, or interruption in TKI) should be considered during the period of growth potential. Research on CML in children is at a relatively slow pace, largely due to the rarity of the disease. This provides a unique opportunity for research in population-dense LMICs, as several tertiary centers tend to have a sizable cohort of children and adolescents with CML on follow-up. This narrative summarises the challenges and opportunities in dealing with CML in children, particularly in reference to a center in LMIC.

Cytopenia among CML Patients on Imatinib in Kenya: Types, Grades, and Time Course

Background

Imatinib mesylate is the gold standard for the treatment of all phases of Philadelphia-positive chronic myeloid leukemia. Patients on imatinib treatment may develop cytopenia due to drug toxicity. This study aimed to determine the types, grades, and time course of cytopenia in CML patients on imatinib at a Nairobi hospital.

Methods

This was a cross-sectional descriptive study of adult patients aged ≥18 years followed up at the Glivec International Patient Access Program (GIPAP) clinic from 2007 to 2015. Patients who developed cytopenia within 12 months of initiating imatinib were eligible. Clinical and hematologic data were retrieved from the patients' charts and entered into a study proforma. Measures of central tendency such as mean, median, mode, standard deviation, and variance were used for analysis.

Results

Sixty three percent (63.6%) of the 94 patients developed a monocytopenia, with anemia seen in 34%, neutropenia in 27.6%, and thrombocytopenia in 8% of the 94 patients. Anemia plus neutropenia was the most common bicytopenia at 12.7%. Pancytopenia was seen in only 5 of the 94 patients. Most of the cytopenia was grades 2 and 3. Anemia was present at baseline while neutropenia and thrombocytopenia developed within 12 months of imatinib initiation. Anemia resolved during the first 12 months of therapy while neutropenia and thrombocytopenia resolved within 24–36 months of treatment.

Conclusion

Monocytopenia, especially anemia, was the most common type of cytopenia. The cytopenia was predominantly grade 2, developed in majority of the patients within 6 months after imatinib initiation, and had resolved by 24–36 months after imatinib initiation.

Proteolysis-targeting chimera (PROTAC) for targeted protein degradation and cancer therapy

Proteolysis-targeting chimera (PROTAC) has been developed to be a useful technology for targeted protein degradation. A bifunctional PROTAC molecule consists of a ligand (mostly small-molecule inhibitor) of the protein of interest (POI) and a covalently linked ligand of an E3 ubiquitin ligase (E3). Upon binding to the POI, the PROTAC can recruit E3 for POI ubiquitination, which is subjected to proteasome-mediated degradation. PROTAC complements nucleic acid-based gene knockdown/out technologies for targeted protein reduction and could mimic pharmacological protein inhibition. To date, PROTACs targeting ~ 50 proteins, many of which are clinically validated drug targets, have been successfully developed with several in clinical trials for cancer therapy. This article reviews PROTAC-mediated degradation of critical oncoproteins in cancer, particularly those in hematological malignancies. Chemical structures, cellular and in vivo activities, pharmacokinetics, and pharmacodynamics of these PROTACs are summarized. In addition, potential advantages, challenges, and perspectives of PROTAC technology in cancer therapy are discussed.

Arsenic trioxide-induced p38 MAPK and Akt mediated MCL1 downregulation causes apoptosis of BCR-ABL1-positive leukemia cells

In this study, we investigated the mechanisms underlying arsenic trioxide (ATO)-induced death of human BCR-ABL1-positive K562 and MEG-01 cells. ATO-induced apoptotic death in K562 cells was characterized by ROS-mediated mitochondrial depolarization, MCL1 downregulation, p38 MAPK activation, and Akt inactivation. ATO-induced BCR-ABL1 downregulation caused Akt inactivation but not p38 MAPK activation. Akt inactivation increased GSK3β-mediated MCL1 degradation, while p38 MAPK-mediated NFκB activation coordinated with HDAC1 suppressed MCL1 transcription. Inhibition of p38 MAPK activation or overexpression of constitutively active Akt increased MCL1 expression and promoted the survival of ATO-treated cells. Overexpression of MCL1 alleviated mitochondrial depolarization and cell death induced by ATO. The same pathway was found to be involved in ATO-induced death in MEG-01 cells. Remarkably, YM155 synergistically enhanced the cytotoxicity of ATO on K562 and MEG-01 cells through suppression of MCL1 and survivin. Collectively, our data indicate that ATO-induced p38 MAPK- and Akt-mediated MCL1 downregulation triggers apoptosis in K562 and MEG-01 cells, and that p38 MAPK activation is independent of ATO-induced BCR-ABL1 suppression.

Personal tumor antigens in blood malignancies: genomics-directed identification and targeting

Hematological malignancies have long been at the forefront of the development of novel immune-based treatment strategies. The earliest successful efforts originated from the extensive body of work in the field of allogeneic hematopoietic stem cell transplantation. These efforts laid the foundation for the recent exciting era of cancer immunotherapy, which includes immune checkpoint blockade, personal neoantigen vaccines, and adoptive T cell transfer. At the heart of the specificity of these novel strategies is the recognition of target antigens presented by malignant cells to T cells. Here, we review the advances in systematic identification of minor histocompatibility antigens and neoantigens arising from personal somatic alterations or recurrent driver mutations. These exciting efforts pave the path for the implementation of personalized combinatorial cancer therapy.

Entire ABL1 Gene Deletion Without BCR/ABL1 Rearrangement in a Female Patient with B-Cell Precursor Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a malignant disease characterized by lymphocytic B-line or T-line cells abnormally proliferating in the bone marrow or extramedullary sites. BCR/ABL1 fusion protein in patients with ALL accounts for acts in 15-30% of B-lineage ALL cases, usually in adolescence. However, entire ABL1 gene deletion without BCR/ABL1 rearrangement is a rare phenomenon in ALL patients. Here we describe the first case of entire ABL1 gene deletion without BCR/ABL1 rearrangement in a female B-ALL patient. Relevant literature is reviewed to explain the association between ABL1 deletion and the pathogenesis/prognosis of this disease. ABL gene deletion can repress the activation of p53 and p73, and disrupt TGF-β signaling pathway to allow malignant cells to invade the normal tissue. The clinical significance of ABL gene deletion needs to be further explored.

Adaptive phenotypic modulations lead to therapy resistance in chronic myeloid leukemia cells

Tyrosine kinase inhibitor (TKI) resistance is a major problem in chronic myeloid leukemia (CML). We generated a TKI-resistant K562 sub-population, K562-IR, under selective imatinib-mesylate pressure. K562-IR cells are CD34-/CD38-, BCR-Abl-independent, proliferate slowly, highly adherent and form intact tumor spheroids. Loss of CD45 and other hematopoietic markers reveal these cells have diverged from their hematopoietic origin. CD34 negativity, high expression of E-cadherin and CD44; decreased levels of CD45 and β-catenin do not fully confer with the leukemic stem cell (LSC) phenotype. Expression analyses reveal that K562-IR cells differentially express tissue/organ development and differentiation genes. Our data suggest that the observed phenotypic shift is an adaptive process rendering cells under TKI stress to become oncogene independent. Cells develop transcriptional instability in search for a gene expression framework suitable for new environmental stresses, resulting in an adaptive phenotypic shift in which some cells partially display LSC-like properties. With leukemic/cancer stem cell targeted therapies underway, the difference between treating an entity and a spectrum of dynamic cellular states will have conclusive effects on the outcome.

Computational Cancer Cell Models to Guide Precision Breast Cancer Medicine

Background: Large-scale screening of drug sensitivity on cancer cell models can mimic in vivo cellular behavior providing wider scope for biological research on cancer. Since the therapeutic effect of a single drug or drug combination depends on the individual patient’s genome characteristics and cancer cells integration reaction, the identification of an effective agent in an in vitro model by using large number of cancer cell models is a promising approach for the development of targeted treatments. Precision cancer medicine is to select the most appropriate treatment or treatments for an individual patient. However, it still lacks the tools to bridge the gap between conventional in vitro cancer cell models and clinical patient response to inhibitors. Methods: An optimal two-layer decision system model is developed to identify the cancer cells that most closely resemble an individual tumor for optimum therapeutic interventions in precision cancer medicine. Accordingly, an optimal grid parameters selection is designed to seek the highest accordance for treatment selection to the patient’s preference for drug response and in vitro cancer cell drug screening. The optimal two-layer decision system model overcomes the challenge of heterology data comparison between the tumor and the cancer cells, as well as between the continual variation of drug responses in vitro and the discrete ones in clinical practice. We simulated the model accuracy using 681 cancer cells’ mRNA and associated 481 drug screenings and validated our results on 315 breast cancer patients drug selection across seven drugs (docetaxel, doxorubicin, fluorouracil, paclitaxel, tamoxifen, cyclophosphamide, lapitinib). Results: Comparing with the real response of a drug in clinical patients, the novel model obtained an overall average accordance over 90.8% across the seven drugs. At the same time, the optimal cancer cells and the associated optimal therapeutic efficacy of cancer drugs are recommended. The novel optimal two-layer decision system model was used on 1097 patients with breast cancer in guiding precision medicine for a recommendation of their optimal cancer cells (30 cancer cells) and associated efficacy of certain cancer drugs. Our model can detect the most similar cancer cells for each individual patient. Conclusion: A successful clinical translation model (optimal two-layer decision system model) was developed to bridge in-vitro basic science to clinical practice in a therapeutic intervention application for the first time. The novel tool kills two birds with one stone. It can help basic science to seek optimal cancer cell models for an individual tumor, while prioritizing clinical drugs’ recommendations in practice. Tool associated platform website: We extended the breast cancer research to 32 more types of cancers across 45 therapy predictions.

The Q-LAMP Method Represents a Valid and Rapid Alternative for the Detection of the BCR-ABL1 Rearrangement in Philadelphia-Positive Leukemias

Molecular detection of the BCR-ABL1 fusion transcripts is necessary for the genetic confirmation of a chronic myeloid leukemia diagnosis and for the risk classification of acute lymphoblastic leukemia. BCR-ABL1 mRNAs are usually identified using a conventional RT-PCR technique according to the BIOMED-1 method. In this study, we evaluated 122 BCR-ABL1-positive samples with the Q-LAMP assay to establish if this technology may represent a valid alternative to the qualitative BIOMED-1 PCR technique usually employed for the detection and the discrimination of the common BCR-ABL1 transcripts (p190 and p210 isoforms). We found a 100% concordance rate between the two methods. Specifically, the p190- and p210-positive samples were amplified by Q-LAMP with a median threshold time (Tt) of 26.70 min (range: 24.45-31.80 min) and 20.26 min (range: 15.25-34.57 min), respectively. A median time of 19.63 was observed in samples displaying both (e13a2/e14a2) p210 isoforms. Moreover, the Q-LAMP assay allowed recognition of the BCR-ABL1 e13a2 and e14a2 isoforms (median Tts 18.48 for e13a2 vs. 26.08 min for e14a2; p < 0.001). Finally, 20 samples harboring rare BCR-ABL1 isoforms (e1a3, e13a3, e14a3, and e19a2) were correctly identified by the Q-LAMP assay. We conclude that the Q-LAMP assay may represent a faster and valid alternative to the qualitative BIOMED-1 RT-PCR for the diagnosis at BCR-ABL1-positive leukemias, especially when samples are analyzed in centers with restricted resources and/or limited technical expertise.

Inhibition of KPNB1 Inhibits Proliferation and Promotes Apoptosis of Chronic Myeloid Leukemia Cells Through Regulation of E2F1

Background

Karyopherin-β1 (KPNB1) belongs to the karyopherin superfamily, which functions as shuttling proteins from the cytoplasm to nuclear. A high level of KPNB1 has been reported in various cancers which promotes cell proliferation and inhibits apoptosis. However, the role of KPNB1 in chronic myeloid leukemia (CML) remains uncertain.

Methods

Expression level of KPNB1 in CML patient samples and cell lines was analyzed by Western blotting. The proliferation assays and colony formation assay were used to study the CML cell proliferation when KPNB1 knockdown in vitro. Next, Western blotting was used to evaluate the effects of KPNB1 on E2F1 and other cell cycle regulators. Then, the location of E2F1 was detected by immunofluorescence. Finally, flow cytometry was used to detect the effect of KPNB1 inhibitor importazole (IPZ) on CML cells.

Results

In this study, we firstly showed that KPNB1 is over-expressed in CML cells. Targeting KPNB1 with small interfering RNA (siRNA) and IPZ reduced proliferation and induced apoptosis of CML cells. The underlying mechanisms were also investigated that E2F1 nuclear transport was blocked after inhibiting KPNB1 with siRNA, suggesting KPNB1 over-expression mediates the excessive nuclear transport of E2F1 in CML cells. Moreover, the expression of the E2F1 targeted molecule such as c-Myc and KPNA2 was markedly reduced. The IPZ arrested CML cells at G2/M phase and induced cell apoptosis.

Conclusion

In summary, our results clearly showed that KPNB1 is over-expressed in CML cells and mediates the translocation of E2F1 into the nucleus of CML cells, thereby inhibition of KPNB1 reduced proliferation and induced apoptosis of CML cells which provides new insights for targeted CML therapies.

Cholesterol grafted cationic lipopolymers: Potential siRNA carriers for selective chronic myeloid leukemia therapy

Synthetic siRNA technology has emerged as a promising approach for molecular therapy of cancer but, despite its potential for post-transcriptional gene silencing, there is an urgent need to develop efficient delivery systems particularly for difficult-to-transfect, anchorage-independent cells. In this study, we designed highly hydrophobic cationic lipopolymers by grafting cholesterol (Chol) onto low-molecular weight (0.6, 1.2, and 2.0 kDa) polyethylenimines (PEIs) to enable specific siRNA therapy to chronic myeloid leukemia (CML) cells. The siRNA binding by PEI-Chol led to nano-sized (100-200 nm diameter) polyplexes with enhanced ζ-potential (+20 to +35 mV) and ability to protect the loaded siRNA completely in fresh serum. The siRNA delivery to CML (K562) cells was proportional to degree of substitution and, unexpectedly, inversely proportional to molecular size of the polymeric backbone. Chol grafting with as little as ~1.0 Chol/PEI on 0.6 and 1.2 kDa PEIs enabled silencing of the reporter Green Fluorescent Protein gene as well as the endogenous BCR-Abl oncogene in K562 cells. The PEI-Chol mediated delivery of siRNAs specific for BCR-Abl and KSP genes significantly arrested the growth the cells which was significantly reflected in colony formation potency of K562 cells. BCR-Able siRNA mediated therapeutic efficacy was also observed in significantly increased caspase activity and apoptosis of K562 cells. Thus, Chol-grafted low-molecular weight PEIs appear to be unique siRNA carriers to realize the molecular therapy in CML cells.

Early Management of CML

PURPOSE OF REVIEW

The marked improvement in clinical outcomes for patients with chronic myeloid leukaemia (CML) can be solely attributed to the introduction of targeted therapies against the fusion oncoprotein, BCR-ABL1. However, patient responses, although generally positive, remain heterogenous. Careful drug selection, ensuring the optimal TKI, is chosen for each patient and involves a complex decision process which incorporates consideration of numerous factors.

RECENT FINDINGS

For some patients, with disease characteristics that indicate adverse intrinsic disease biology, more potent BCR-ABL1 inhibition is often appropriate, whereas other patients with major co-morbidities will benefit from a less aggressive approach to avoid life-shortening toxicities. For the vast majority of patients, the long-term goal of therapy will be the achievement of a deep molecular response and subsequent treatment-free remission and this consideration will play a large part in the drug selection process. We explore early management of CML, from the first presentation through to frontline therapy selection.

New 2,6,9-trisubstituted purine derivatives as Bcr-Abl and Btk inhibitors and as promising agents against leukemia

Bcr-Abl and Btk kinases are among the targets that have been considered for the treatment of leukemia. Therefore, several strategies have focused on the use of inhibitors as chemotherapeutic tools to treat these types of leukemia, such as imatinib (for Bcr-Abl) or ibrutinib (for Btk). However, the efficacy of these drugs has been reduced due to resistance mechanisms, which have motivated the development of new and more effective compounds. In this study, we designed, synthesized and evaluated 2,6,9-trisubstituted purine derivatives as novel Bcr-Abl and Btk inhibitors. We identified 5c and 5d as potent inhibitors of both kinases (IC₅₀ values of 40 nM and 0.58/0.66 μM for Abl and Btk, respectively). From docking and QSAR analyses, we concluded that fluorination of the arylpiperazine system is detrimental to the activity against two kinases, and we also validated our hypothesis that the substitution on the 6-phenylamino ring is important for the inhibition of both kinases. In addition, our studies indicated that most compounds could suppress the proliferation of leukemia and lymphoma cells (HL60, MV4-11, CEM, K562 and Ramos cells) at low micromolar concentrations in vitro. Finally, we preliminarily demonstrated that 5c inhibited the downstream signaling of both kinases in the respective cell models. Therefore, 5c or 5d possessed potency to be further optimized as anti-leukemia drugs by simultaneously inhibiting the Bcr-Abl and Btk kinases.

Assessment on the binding characteristics of dasatinib, a tyrosine kinase inhibitor to calf thymus DNA: insights from multi-spectroscopic methodologies and molecular docking as well as DFT calculation

The binding characteristics of calf thymus DNA (ct-DNA) with dasatinib (DSTN), a tyrosine kinase inhibitor was assessed through multi-spectroscopic methodologies and viscosity measurement combined with molecular docking as well as DFT calculation to understand the binding mechanism, affinity of DSTN onto ct-DNA, effect of DSTN on ct-DNA conformation, and among others. The results confirmed DSTN bound onto ct-DNA, leading to forming the DSTN-ct-DNA complex with the binding constant of 4.82 × 10³ M^-1 at 310 K. DSTN preferentially inserted to the minor groove of ct-DNA with rich A-T region, that was the binding mode of DSTN onto ct-DNA was groove binding. The enthalpic change (ΔH⁰) and entropic change (ΔS⁰) during the binding process of DSTN with ct-DNA were 128.9 kJ mol^-1 and 489.2 J mol^-1 K^-1, respectively, confirming clearly that the association of DSTN with ct-DNA was an endothermic process and the dominative driven-force was hydrophobic interaction. Meanwhile, the results also indicated that there was a certain extent of electrostatic force and hydrogen bonding, but they maybe play an auxiliary role. The CD measurement results confirmed the alteration in the helical configuration of ct-DNA but almost no change in the base stacking after binding DSTN. The results revealed that there was the obvious change in the conformation, the dipole moment, and the atomic charge distribution of DSTN in the B-DNA complexes, compared with free DSTN, to satisfy the conformational adaptation. From the obtained fronitier molecular orbitals of DSTN, it can be inferred that the nature of DSTN alters with the change of the environment around DSTN. Communicated by Ramaswamy H. Sarma.

Progress on small-molecule proteolysis-targeting chimeras

Proteolysis-targeting chimeras (PROTACs) have received much attention for their promising therapeutic intervention in recent years. These molecules, with the mechanism of simultaneous recruitment of target protein and an E3 ligase, can trigger the cellular ubiquitin–proteasome system to degrade the target proteins. This article systematically introduces the mechanism of small-molecule PROTACs, and summarized the research progress of small-molecule PROTACs. The prospect for further application and the problems to be solved are also discussed.

Structural Variants as a Basis for Targeted Therapies in Hematological Malignancies

Structural variants (SV) are changes in the genomic landscape that can alter gene expression levels and thus lead to disease development. The most common and best studied SVs in hematological malignancies are chromosomal translocations. Here, parts of two genes that are normally on different chromosomes come into close proximity due to a failure in DNA repair. As a consequence, fusion proteins which show a different function and/or cellular localization compared to the two original proteins are expressed, sometimes even at different levels. The identification of chromosomal translocations is often used to identify the specific disease a patient is suffering from. In addition, SVs such as deletions, duplications, inversions and single nucleotide polymorphisms (SNPs) can occur in hematopoietic cells and lead to their malignant transformations. Changes in the 3D genome structure have also recently been shown to impact disease development. In this review, we describe a variety of SVs occurring in different subtypes of hematological malignancies. Currently, most therapeutic approaches target fusion proteins which are the cellular product of chromosomal translocations. However, amplifications and SNPs also play a role in disease progression and can be targeted. We present some examples for different types of structural variants and how they are currently treated.

Assessing Measurable Residual Disease in Chronic Myeloid Leukemia. BCR-ABL1 IS in the Avant-Garde of Molecular Hematology

Chronic myelogenous leukemia (CML) is a malignancy of the myeloid cell lineage characterized by a recurrent chromosomal abnormality: the Philadelphia chromosome, which results from the reciprocal translocation of the chromosomes 9 and 22. The Philadelphia chromosome contains a fusion gene called BCR-ABL1. The BCR-ABL1 codes for an aberrantly functioning tyrosine kinase that drives the malignant proliferation of the founding clone. The advent of tyrosine kinase inhibitors (TKI) represents a landmark in the treatment of CML, that has led to tremendous improvement in the remission and survival rates. Since the introduction of imatinib, the first TKI, several other TKI have been approved that further broadened the arsenal against CML. Patients treated with TKIs require sensitive monitoring of BCR-ABL1 transcripts with quantitative real-time polymerase chain reaction (qRT-PCT), which has become an essential part of managing patients with CML. In this review, we discuss the importance of the BCR-ABL1 assay, and we highlight the growing importance of BCR-ABL1 dynamics. We also introduce a mathematical correction for the BCR-ABL1 assay that could help homogenizing the use of the ABL1 as a control gene. Finally, we discuss the growing body of evidence concerning treatment-free remission. Along with the continuous improvement in the therapeutic arsenal against CML, the molecular monitoring of CML represents the avant-garde in the struggle to make CML a curable disease.

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.

Discovery of novel Bcr-AblT315I inhibitors with flexible linker. Part 1: Confirmation optimization of phenyl-1H-indazol-3-amine as hinge binding moiety

As a continuation to our research, a series of novel Bcr-Abl inhibitors incorporated with 6-phenyl-1H-indazol-3-amine as hinge binding moiety (HBM) were developed based on confirmation analysis. Biological results indicated that these compounds exhibited an enhanced inhibition against Bcr-Abl^WT and Bcr-Abl^T315I in kinases assays, along with improved anti-proliferative activities in K562 cell assays. In particular, compound Y9 displayed comparable potency with that of imatinib. It potently inhibited Bcr-Abl^WT and Bcr-Abl^T315I kinases with IC₅₀ of 0.043 μM and 0.17 μM, respectively. Furthermore, compound Y9 inhibited the proliferation of K562 and K562R cells with IC₅₀ of 1.65 μM and 5.42 μM, respectively. Therefore, 6-phenyl-1H-indazol-3amine as HBM, combined with flexible linker, is a successful strategy contribute to research on T315I mutant resistance, and compound Y9 could be served as a starting point for further optimization.

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

Background

Human 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/Methods

K562 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).

Results

Our 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.

Conclusions

Inhibition 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.

Monitoring Chronic Myeloid Leukemia: How Molecular Tools May Drive Therapeutic Approaches

More than 15 years ago, imatinib entered into the clinical practice as a "magic bullet"; from that point on, the prognosis of patients affected by chronic myeloid leukemia (CML) became comparable to that of aged-matched healthy subjects. The aims of treatment with tyrosine kinase inhibitors (TKIs) are for complete hematological response after 3 months of treatment, complete cytogenetic response after 6 months, and a reduction of the molecular disease of at least 3 logs after 12 months. Patients who do not reach their goal can switch to another TKI. Thus, the molecular monitoring of response is the main consideration of management of CML patients. Moreover, cases in deep and persistent molecular response can tempt the physician to interrupt treatment, and this "dream" is possible due to the quantitative PCR. After great international effort, today the BCR-ABL1 expression obtained in each laboratory is standardized and expressed as "international scale." This aim has been reached after the establishment of the EUTOS program (in Europe) and the LabNet network (in Italy), the platforms where biologists meet clinicians. In the field of quantitative PCR, the digital PCR is now a new and promising, sensitive and accurate tool. Some authors reported that digital PCR is able to better classify patients in precise "molecular classes," which could lead to a better identification of those cases that will benefit from the interruption of therapy. In addition, digital PCR can be used to identify a point mutation in the ABL1 domain, mutations that are often responsible for the TKI resistance. In the field of resistance, a prominent role is played by the NGS that enables identification of any mutation in ABL1 domain, even at sub-clonal levels. This manuscript reviews how the molecular tools can lead the management of CML patients, focusing on the more recent technical advances.

Protective autophagy or autophagic death: effects of BEZ235 on chronic myelogenous leukemia

Purpose

To investigate the effects of BEZ235 on chronic myeloid leukemia (CML) cells.

Methods

MTS assay was used to detect the proliferation of CML cells. The proteins expression were detected by Western blot assay. The effects of BEZ235 on autophagy in CML cells were verified through transmission electron microscopy and evaluated by laser confocal microscopy. Annexin V-FITC/PI double staining flow cytometry was used to detect apoptosis. A xenograft model was established to observe the therapeutic effect of BEZ235 in vivo.

Results

BEZ235 could inhibit the proliferation of CML cells; CQ and 3-MA could increase the proliferation inhibition and Z-VAD-FMK can reduce the proliferation inhibition of BEZ235 on CML cells (P<0.05). Results of TEM showed that the autophagosomes of CML cells treated with BEZ235 increased (P<0.05). The results by confocal microscopy showed that the autophagic activity of K562 cells increased with BEZ235 treatment. When BEZ235 combined with CQ, BEZ235-induced autophagic flow was blocked. FCM results showed that BEZ235 could induces apoptosis in CML cells. Z-VAD-FMK could decrease the apoptosis of CML cells induced by BEZ235. CQ increased the apoptosis of CML cells induced by BEZ235 (P<0.05). Western blot showed that BEZ235 inhibited the phosphorylation of AKT and S6K. BEZ235 alone could upregulate the expression of cleaved caspase-3 and LC3II. When combined with Z-VAD-FMK, the expression of cleaved caspase-3 was lower than that of BEZ235 alone. When combined with CQ, the expression of cleaved caspase-3 and LC3II were higher than those of BEZ235 alone (P<0.05). BEZ235 could inhibit the growth of xenografts of CML cell line.

Conclusion

BEZ235 can inhibit the proliferation of CML cells, induce apoptosis, and enhance autophagy activity. It induces protective autophagy. The combination of CQ can enhance the apoptosis and proliferation inhibition of CML cells induced by BEZ235.

Nilotinib interferes with cell cycle, ABC transporters and JAK-STAT signaling pathway in CD34+/lin- cells of patients with chronic phase chronic myeloid leukemia after 12 months of treatment

Chronic myeloid leukemia (CML) is characterized by the constitutive tyrosine kinase activity of the oncoprotein BCR-ABL1 in myeloid progenitor cells that activates multiple signal transduction pathways leading to the leukemic phenotype. The tyrosine-kinase inhibitor (TKI) nilotinib inhibits the tyrosine kinase activity of BCR-ABL1 in CML patients. Despite the success of nilotinib treatment in patients with chronic-phase (CP) CML, a population of Philadelphia-positive (Ph+) quiescent stem cells escapes the drug activity and can lead to drug resistance. The molecular mechanism by which these quiescent cells remain insensitive is poorly understood. The aim of this study was to compare the gene expression profiling (GEP) of bone marrow (BM) CD34+/lin- cells from CP-CML patients at diagnosis and after 12 months of nilotinib treatment by microarray, in order to identify gene expression changes and the dysregulation of pathways due to nilotinib action. We selected BM CD34+/lin- cells from 78 CP-CML patients at diagnosis and after 12 months of first-line nilotinib therapy and microarray analysis was performed. GEP bioinformatic analyses identified 2,959 differently expressed probes and functional clustering determined some significantly enriched pathways between diagnosis and 12 months of nilotinib treatment. Among these pathways, we observed the under expression of 26 genes encoding proteins belonging to the cell cycle after 12 months of nilotinib treatment which led to the up-regulation of chromosome replication, cell proliferation, DNA replication, and DNA damage checkpoint at diagnosis. We demonstrated the under expression of the ATP-binding cassette (ABC) transporters ABCC4, ABCC5, and ABCD3 encoding proteins which pumped drugs out of the cells after 12 months of nilotinib. Moreover, GEP data demonstrated the deregulation of genes involved in the JAK-STAT signaling pathway. The down-regulation of JAK2, IL7, STAM, PIK3CA, PTPN11, RAF1, and SOS1 key genes after 12 months of nilotinib could demonstrate the up-regulation of cell cycle, proliferation and differentiation via MAPK and PI3K-AKT signaling pathways at diagnosis.