The chronic myelogenous leukemia-specific P210 protein is the product of the bcr/abl hybrid gene

Leukaemia exposure alters the transcriptional profile and function of BCR::ABL1 negative macrophages in the bone marrow niche

Macrophages are fundamental cells of the innate immune system that support normal haematopoiesis and play roles in both anti-cancer immunity and tumour progression. Here we use a chimeric mouse model of chronic myeloid leukaemia (CML) and human bone marrow (BM) derived macrophages to study the impact of the dysregulated BM microenvironment on bystander macrophages. Utilising single-cell RNA sequencing (scRNA-seq) of Philadelphia chromosome (Ph) negative macrophages we reveal unique subpopulations of immature macrophages residing in the CML BM microenvironment. CML exposed macrophages separate from their normal counterparts by reduced expression of the surface marker CD36, which significantly reduces clearance of apoptotic cells. We uncover aberrant production of CML-secreted factors, including the immune modulatory protein lactotransferrin (LTF), that suppresses efferocytosis, phagocytosis, and CD36 surface expression in BM macrophages, indicating that the elevated secretion of LTF is, at least partially responsible for the supressed clearance function of Ph- macrophages.

Single-Cell Plasmonic Immunosandwich Assay Reveals the Modulation of Nucleocytoplasmic Localization Fluctuation of ABL1 on Cell Migration

Cell migration is an essential process of cancer metastasis. The spatiotemporal dynamics of signaling molecules influences cellular phenotypic outcomes. It has been increasingly documented that the Abelson (ABL) family kinases play critical roles in solid tumors. However, ABL1's shuttling dynamics in cell migration still remains unexplored. This is mainly because tools permitting the investigation of translocation dynamics of proteins in single living cells are lacking. Herein, to bridge this gap, we developed a unique multifunctional integrated single-cell analysis method that enables long-term observation of cell migration behavior and monitoring of signaling proteins and complexes at the subcellular level. We found that the shuttling of ABL1's to the cytoplasm results in a higher migration speed, while its trafficking back to the nucleus leads to a lower one. Furthermore, our results indicated that fluctuant protein-protein interactions between 14-3-3 and ABL1 modulate ABL1's nucleocytoplasmic fluctuation and eventually affect the cell speed. Importantly, based on these new insights, we demonstrated that disturbing ABL1's nuclear export traffic and 14-3-3-ABL1 complexes formation can effectively suppress cell migration. Thus, our method opens up a new possibility for simultaneous tracking of internal molecular mechanisms and cell behavior, providing a promising tool for the in-depth study of cancer.

Discovery of 3-((3-amino-1H-indazol-4-yl)ethynyl)-N-(4-((4-ethylpiperazin-1-yl)methyl)-3-(trifluoromethyl)phenyl)benzamide (AKE-72), a potent Pan-BCR-ABL inhibitor including the T315I gatekeeper resistant mutant

BCR-ABL inhibition is an effective therapeutic approach for the treatment of chronic myeloid leukaemia (CML). Herein, we report the discovery of AKE-72 (5), a diarylamide 3-aminoindazole, as a potent pan-BCR-ABL inhibitor, including the imatinib-resistant mutant T315I. A focussed array of compounds 4a, 4b, and 5 has been designed based on our previously reported indazole I to improve its BCR-ABL^T315I inhibitory activity. Replacing the morpholine moiety of I with the privileged tail (4-ethylpiperazin-1-yl)methyl afforded 5 (AKE-72) with IC₅₀ values of < 0.5 nM, and 9 nM against BCR-ABL^WT and BCR-ABL^T315I, respectively. Moreover, AKE-72 potently inhibited a panel of other clinically important mutants in single-digit nanomolar IC₅₀ values. AKE-72 elicited remarkable anti-leukemic activity against K-562 cell line (GI₅₀ < 10 nM, TGI = 154 nM). In addition, AKE-72 strongly inhibited the proliferation of Ba/F3 cells expressing native BCR-ABL or its T315I mutant. Overall, AKE-72 may serve as a promising candidate for the treatment of CML, including those harbouring T315I mutation.

LIMS-Kinase provides sensitive and generalizable label-free in vitro measurement of kinase activity using mass spectrometry

Measurements of kinase activity are important for kinase-directed drug development, analysis of inhibitor structure and function, and understanding mechanisms of drug resistance. Sensitive, accurate, and miniaturized assay methods are crucial for these investigations. Here, we describe a label-free, high-throughput mass spectrometry-based assay for studying individual kinase enzymology and drug discovery in a purified system, with a focus on validated drug targets as benchmarks. We demonstrate that this approach can be adapted to many known kinase substrates and highlight the benefits of using mass spectrometry to measure kinase activity in vitro, including increased sensitivity. We speculate that this approach to measuring kinase activity will be generally applicable across most of the kinome, enabling research on understudied kinases and kinase drug discovery.

Asymmetric Hairpins DNA Encapsulated Silver Nanoclusters for In Situ Fluorescence Imaging of Fusion Gene Isoforms in Bone Marrow

Rapid and accurate imaging of the BCR/ABL fusion gene isoforms (e.g., e13a2, e14a2 and co-expression type) of chronic myeloid leukemia (CML) is of vital importance to first-line drug selection, but there is no assay that meets clinical needs (e.g., clinical kits > 18 h without isoforms information). Herein, an in situ imaging platform is developed for the rapid and accurate detection of CML fusion gene isoforms using asymmetric sequence-enhanced hairpins DNA encapsulated silver nanoclusters (ADHA) and catalyzed hairpin assembly (CHA). The specific detection of e13a2 and e14a2 fusion gene isoforms with detection limits of 19.2 am (11.558 copies µL-1 ) and 32.56 am (19.601 copies µL-1 ) in one-pot is achieved. The feasibility of the developed assay for real-world applications are demonstrated by one-step fluorescence imaging (40 min) of e13a2, e14a2 and co-expression type in bone marrow quantitatively (International Standard: 15.66%-168.878%) and further validated by cDNA-sequencing. This work suggests that the developed imaging platform holds great potential for rapid identification of the fusion gene isoforms and isoform related treatment monitoring.

Abl kinases can function as suppressors of tumor progression and metastasis

Introduction

Abl family kinases function as proto-oncogenes in various leukemias, and pro-tumor functions have been discovered for Abl kinases in many solid tumors as well. However, a growing body of evidence indicates that Abl kinases can function to suppress tumor cell proliferation and motility and tumor growth in vivo in some settings.

Methods

To investigate the role of Abl kinases in tumor progression, we used RNAi to generate Abl-deficient cells in a model of androgen receptor-indifferent, metastatic prostate cancer. The effect of Abl kinase depletion on tumor progression and metastasis was studied in an in vivo orthotopic model, and tumor cell motility, 3D growth, and signaling was studied in vitro.

Results

Reduced Abl family kinase expression resulted in a highly aggressive, metastatic phenotype in vivo that was associated with AKT pathway activation, increased growth on 3D collagen matrix, and enhanced cell motility in vitro. Inhibiting AKT pathway signaling abolished the increased 3D growth of Abl-deficient cells, while treatment with the Abl kinase inhibitor, imatinib, promoted 3D growth of multiple additional tumor cell types. Moreover, Abl kinase inhibition also promoted soft-agar colony formation by pre-malignant fibroblasts.

Conclusions

Collectively, our data reveal that Abl family kinases can function to suppress malignant cell phenotypes in vitro, and tumor progression and metastasis in vivo.

Bone mesenchymal stem cell extracellular vesicles delivered miR let-7-5p alleviate endothelial glycocalyx degradation and leakage via targeting ABL2

BACKGROUND

Endothelial glycocalyx (EG) is an active player and treatment target in inflammatory-related vascular leakage. The bone marrow mesenchymal stem cells (bMSCs) are promising potential treatments for leakage; however, the therapeutic effect and mechanism of bMSC on EG degradation needs to be elucidated.

METHODS

EG degradation and leakage were evaluated in both lipopolysaccharide (LPS)-induced mice ear vascular leakage model and LPS-stimulated human umbilical vein endothelial cells (HUVECs) model treated with bMSCs. Extracellular vesicles (EVs) were extracted from bMSCs and the containing microRNA profile was analyzed. EV and miR let-7-5p were inhibited to determine their function in the therapeutic process. The ABL2 gene was knockdown in HUVECs to verify its role as a therapeutic target in EG degradation.

RESULTS

bMSCs treatment could alleviate LPS-induced EG degradation and leakage in vivo and in vitro, whereas EVs/let-7-5p-deficient bMSCs were insufficient to reduce EG degradation. LPS down-regulated the expression of let-7-5p while upregulated endothelial expression of ABL2 in HUVECs and induced EG degradation and leakage. bMSC-EVs uptaken by HUVECs could deliver let-7-5p targeting endothelial ABL2, which suppressed the activation of downstream p38MAPK and IL-6, IL-1β levels, and thus reversed LPS-induced EG degradation and leakage.

CONCLUSION

bMCSs alleviate LPS-induced EG degradation and leakage through EV delivery of miR let-7-5p targeting endothelial ABL2.

Decoding Oncofusions: Unveiling Mechanisms, Clinical Impact, and Prospects for Personalized Cancer Therapies

Cancer-associated gene fusions, also known as oncofusions, have emerged as influential drivers of oncogenesis across a diverse range of cancer types. These genetic events occur via chromosomal translocations, deletions, and inversions, leading to the fusion of previously separate genes. Due to the drastic nature of these mutations, they often result in profound alterations of cellular behavior. The identification of oncofusions has revolutionized cancer research, with advancements in sequencing technologies facilitating the discovery of novel fusion events at an accelerated pace. Oncofusions exert their effects through the manipulation of critical cellular signaling pathways that regulate processes such as proliferation, differentiation, and survival. Extensive investigations have been conducted to understand the roles of oncofusions in solid tumors, leukemias, and lymphomas. Large-scale initiatives, including the Cancer Genome Atlas, have played a pivotal role in unraveling the landscape of oncofusions by characterizing a vast number of cancer samples across different tumor types. While validating the functional relevance of oncofusions remains a challenge, even non-driver mutations can hold significance in cancer treatment. Oncofusions have demonstrated potential value in the context of immunotherapy through the production of neoantigens. Their clinical importance has been observed in both treatment and diagnostic settings, with specific fusion events serving as therapeutic targets or diagnostic markers. However, despite the progress made, there is still considerable untapped potential within the field of oncofusions. Further research and validation efforts are necessary to understand their effects on a functional basis and to exploit the new targeted treatment avenues offered by oncofusions. Through further functional and clinical studies, oncofusions will enable the advancement of precision medicine and the drive towards more effective and specific treatments for cancer patients.

Proteolysis-Targeting Chimeras (PROTACs) targeting the BCR-ABL for the treatment of chronic myeloid leukemia - a patent review

INTRODUCTION

PROteolysis-TArgeting Chimeras (PROTACs) allow the selective degradation of a protein of interest (POI) by the ubiquitin-proteasome system (UPS). With this unique mechanism of action, the research and development of PROTACs that target the Breakpoint Cluster Region Abelson (BCR-ABL) tyrosine kinase (TK) has been increasing dramatically, as they are promising molecules in the treatment of Chronic Myeloid Leukemia (CML), one of the main hematological malignancies, which results from an uncontrolled myeloproliferation due to the constitutive activation of BCR-ABL.

AREAS COVERED

This review summarizes the patents/applications published in the online databases like Espacenet or World Intellectual Property Organization regarding PROTACs that promote BCR-ABL degradation. Patents will be described mostly in terms of chemical structure, biochemical/pharmacological activities, and potential clinical applications.

EXPERT OPINION

The recent discovery of the enormous potential of PROTACs led to the creation of new compounds capable of degrading BCR-ABL for the treatment of CML. Although still in reduced numbers, and in the pre-clinical phase of development, some compounds have already been shown to overcome some of the difficulties presented by conventional BCR-ABL inhibitors, such as the well-known imatinib. Therefore, it is very likely that some of the present PROTACs will enter future CML therapy in the coming years.

Creation of Philadelphia chromosome by CRISPR/Cas9-mediated double cleavages on BCR and ABL1 genes as a model for initial event in leukemogenesis

The Philadelphia (Ph) chromosome was the first translocation identified in leukemia. It is supposed to be generated by aberrant ligation between two DNA double-strand breaks (DSBs) at the BCR gene located on chromosome 9q34 and the ABL1 gene located on chromosome 22q11. Thus, mimicking the initiation process of translocation, we induced CRISPR/Cas9-mediated DSBs simultaneously at the breakpoints of the BCR and ABL1 genes in a granulocyte-macrophage colony-stimulating factor (GM-CSF) dependent human leukemia cell line. After transfection of two single guide RNAs (sgRNAs) targeting intron 13 of the BCR gene and intron 1 of the ABL1 gene, a factor-independent subline was obtained. In the subline, p210 BCR::ABL1 and its reciprocal ABL1::BCR fusions were generated as a result of balanced translocation corresponding to the Ph chromosome. Another set of sgRNAs targeting intron 1 of the BCR gene and intron 1 of the ABL1 gene induced a factor-independent subline expressing p190 BCR::ABL1. Both p210 and p190 BCR::ABL1 induced factor-independent growth by constitutively activating intracellular signaling pathways for transcriptional regulation of cell cycle progression and cell survival that are usually regulated by GM-CSF. These observations suggested that simultaneous DSBs at the BCR and ABL1 gene breakpoints are initiation events for oncogenesis in Ph+ leukemia. (200/200 words).

N6-Methyladenosine RNA Modification in Normal and Malignant Hematopoiesis

Over 170 nucleotide variants have been discovered in messenger RNAs (mRNAs) and non-coding RNAs so far. However, only a few of them, including N6-methyladenosine (m6A), 5-methylcytidine (m5C), and N1-methyladenosine (m1A), could be mapped in the transcriptome. These RNA modifications appear to be dynamically regulated, with writer, eraser, and reader proteins being identified for each modification. As a result, there is a growing interest in studying their biological impacts on normal bioprocesses and tumorigenesis over the past few years. As the most abundant internal modification in eukaryotic mRNAs, m6A plays a vital role in the post-transcriptional regulation of mRNA fate via regulating almost all aspects of mRNA metabolism, including RNA splicing, nuclear export, RNA stability, and translation. Studies on mRNA m6A modification serve as a great example for exploring other modifications on mRNA. In this chapter, we will review recent advances in the study of biological functions and regulation of mRNA modifications, specifically m6A, in both normal hematopoiesis and malignant hematopoiesis. We will also discuss the potential of targeting mRNA modifications as a treatment for hematopoietic disorders.

BH3 mimetics in combination with nilotinib or ponatinib represent a promising therapeutic strategy in blast phase chronic myeloid leukemia

Dysregulation of the BCL-2 family is implicated in protecting chronic myeloid leukemia (CML) cells from intracellular damage and BCR::ABL1-inhibition with tyrosine kinase inhibitors (TKIs) and may be a viable therapeutic target in blast phase (BP-)CML, for which treatment options are limited. BH3 mimetics, a class of small molecule inhibitors with high-specificity against the prosurvival members of the BCL-2 family, have displayed clinical promise in the treatment of chronic lymphocytic and acute myeloid leukemia as single agents and in combination with standard-of-care therapies. Here we present the first comparison of inhibition of BCL-2 prosurvival proteins BCL-2, BCL-xL and MCL-1 in combination with a second or third generation TKI, crucially with comparisons drawn between myeloid and lymphoid BP-CML samples. Co-treatment of four BP-CML cell lines with the TKIs nilotinib or ponatinib and either BCL-2 (venetoclax), MCL-1 (S63845) or BCL-xL (A-1331852) inhibitors resulted in a synergistic reduction in cell viability and increase in phosphatidylserine (PS) presentation. Nilotinib with BH3 mimetic combinations in myeloid BP-CML patient samples triggered increased induction of apoptosis over nilotinib alone, and a reduction in colony-forming capacity and CD34⁺ fraction, while this was not the case for lymphoid BP-CML samples tested. While some heterogeneity in apoptotic response was observed between cell lines and BP-CML patient samples, the combination of BCL-xL and BCR::ABL1 inhibition was consistently effective in inducing substantial apoptosis. Further, while BH3 mimetics showed little efficacy as single agents, dual-inhibition of BCL-2 prosurvival proteins dramatically induced apoptosis in all cell lines tested and in myeloid BP-CML patient samples compared to healthy donor samples. Gene expression and protein level analysis suggests a protective upregulation of alternative BCL-2 prosurvival proteins in response to BH3 mimetic single-treatment in BP-CML. Our results suggest that BH3 mimetics represent an interesting avenue for further exploration in myeloid BP-CML, for which alternative treatment options are desperately sought.

Non-Coding RNAs Are Implicit in Chronic Myeloid Leukemia Therapy Resistance

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm initiated by the presence of the fusion gene BCR::ABL1. The development of tyrosine kinase inhibitors (TKIs) highly specific to p210^BCR-ABL1, the constitutively active tyrosine kinase encoded by BCR::ABL1, has greatly improved the prognosis for CML patients. Now, the survival rate of CML nearly parallels that of age matched controls. However, therapy resistance remains a persistent problem in the pursuit of a cure. TKI resistance can be attributed to both BCR::ABL1 dependent and independent mechanisms. Recently, the role of non-coding RNAs (ncRNAs) has been increasingly explored due to their frequent dysregulation in a variety of malignancies. Specifically, microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs) have been shown to contribute to the development and progression of therapy resistance in CML. Since each ncRNA exhibits multiple functions and is capable of controlling gene expression, they exert their effect on CML resistance through a diverse set of mechanisms and pathways. In most cases ncRNAs with tumor suppressing functions are silenced in CML, while those with oncogenic properties are overexpressed. Here, we discuss the relevance of many aberrantly expressed ncRNAs and their effect on therapy resistance in CML.

Does the pursuit of scientific excellence serve or hamper translational medical research: an historical perspective from hematological malignancies

Despite enormous global investment, translational medical research faces considerable challenges and patients, and their doctors are frequently frustrated by the apparent lack of research activity or progress. Understanding the factors that prevent innovative research discoveries from making it to clinical trials is a multifaceted problem. However, one question that must be addressed is whether the nature of current research activity and the factors that influence the conduct of pre-clinical research, permit, or hamper the timely progression of laboratory-based observations to proof of concept (PoC) clinical trials. Inherent in this question is to what extent a deep mechanistic understanding of a potential new therapy is required before commencing PoC studies, and whether patients are better served when mechanistic and clinical studies progress side by side rather than in a more linear fashion. Here we address these questions by revisiting the historical development of hugely impactful and paradigm-changing innovations in the treatment of hematological cancers. First, we compare the history and route to clinical PoC, of two molecularly-targeted therapies that are BCR:ABL inhibitors in chronic myeloid leukaemia and all-trans retinoic acid (ATRA) in acute promyelocytic leukaemia (APL). We then discuss the history of arsenic trioxide as additional APL therapy, and the repurposing of thalidomide as effective multiple myeloma therapy. These stories have surprising elements of commonality that demand debate about the modern-day hard and soft governance of medical research and whether these processes appropriately align the priorities of advancing scientific knowledge and the need of patients.

Critical DNA damaging pathways in tumorigenesis

The acquisition of DNA damage is an early driving event in tumorigenesis. Premalignant lesions show activated DNA damage responses and inactivation of DNA damage checkpoints promotes malignant transformation. However, DNA damage is also a targetable vulnerability in cancer cells. This requires a detailed understanding of the cellular and molecular mechanisms governing DNA integrity. Here, we review current work on DNA damage in tumorigenesis. We discuss DNA double strand break repair, how repair pathways contribute to tumorigenesis, and how double strand breaks are linked to the tumor microenvironment. Next, we discuss the role of oncogenes in promoting DNA damage through replication stress. Finally, we discuss our current understanding on DNA damage in micronuclei and discuss therapies targeting these DNA damage pathways.

Ex Vivo Expansion of Phenotypic and Transcriptomic Chronic Myeloid Leukemia Stem Cells

Despite decades of research, standard therapies remain ineffective for most leukemias, pushing toward an essential unmet need for targeted drug screens. Moreover, preclinical drug testing is an important consideration for success of clinical trials without affecting non-transformed stem cells. Using the transgenic chronic myeloid leukemia (CML) mouse model, we determine that leukemic stem cells (LSCs) are transcriptionally heterogenous with a preexistent drug-insensitive signature. To test targeting of potentially important pathways, we establish ex vivo expanded LSCs that have long-term engraftment and give rise to multilineage hematopoiesis. Expanded LSCs share transcriptomic signatures with primary LSCs including enrichment in Wnt, JAK-STAT, MAPK, mTOR and transforming growth factor β signaling pathways. Drug testing on expanded LSCs show that transforming growth factor β and Wnt inhibitors had significant effects on the viability of LSCs, but not leukemia-exposed healthy HSCs. This platform allows testing of multiple drugs at the same time to identify vulnerabilities of LSCs.

Designing Novel BCR-ABL Inhibitors for Chronic Myeloid Leukemia with Improved Cardiac Safety

Development of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogene constitutes an effective approach for the treatment of chronic myeloid leukemia (CML) and/or acute lymphoblastic leukemia. However, currently available inhibitors are limited by drug resistance and toxicity. Ponatinib, a third-generation inhibitor, has demonstrated excellent efficacy against both wild type and mutant BCR-ABL kinase, including the "gatekeeper" T315I mutation that is resistant to all other currently available TKIs. However, it is one of the most cardiotoxic of the FDA-approved TKIs. Herein, we report the structure-guided design of a novel series of potent BCR-ABL inhibitors, particularly for the T315I mutation. Our drug design paradigm was coupled to iPSC-cardiomyocyte models. Systematic structure-activity relationship studies identified two compounds, 33a and 36a, that significantly inhibit the kinase activity of both native BCR-ABL and the T315I mutant. We have identified the most cardiac-safe TKIs reported to date, and they may be used to effectively treat CML patients with the T315I mutation.

Histologically resolved multiomics enables precise molecular profiling of human intratumor heterogeneity

Both the composition of cell types and their spatial distribution in a tissue play a critical role in cellular function, organ development, and disease progression. For example, intratumor heterogeneity and the distribution of transcriptional and genetic events in single cells drive the genesis and development of cancer. However, it can be challenging to fully characterize the molecular profile of cells in a tissue with high spatial resolution because microscopy has limited ability to extract comprehensive genomic information, and the spatial resolution of genomic techniques tends to be limited by dissection. There is a growing need for tools that can be used to explore the relationship between histological features, gene expression patterns, and spatially correlated genomic alterations in healthy and diseased tissue samples. Here, we present a technique that combines label-free histology with spatially resolved multiomics in unfixed and unstained tissue sections. This approach leverages stimulated Raman scattering microscopy to provide chemical contrast that reveals histological tissue architecture, allowing for high-resolution in situ laser microdissection of regions of interests. These microtissue samples are then processed for DNA and RNA sequencing to identify unique genetic profiles that correspond to distinct anatomical regions. We demonstrate the capabilities of this technique by mapping gene expression and copy number alterations to histologically defined regions in human oral squamous cell carcinoma (OSCC). Our approach provides complementary insights in tumorigenesis and offers an integrative tool for macroscale cancer tissues with spatial multiomics assessments.

The Molecular Role of HIF1α Is Elucidated in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is potentially fatal blood cancer, but there is an unmet need to discover novel molecular biomarkers. The hypothesis of this study aimed to elucidate the relationship of HIF1α with the redox system, Krebs cycles, notch1, and other regulatory proteins to better understand the pathophysiology and clinical relevance in chronic myeloid leukemia (CML) patients, as the molecular mechanism of this axis is still not clear. This study included CML patient samples (n = 60; 60: blood; 10: bone marrow tissues) and compared them with healthy controls (n = 20; blood). Clinical diagnosis confirmed on bone marrow aspiration, marrow trephine biopsy, and BCR/ABL1 translocation. Cases were subclassified into chronic, accelerated, and blast crises as per WHO guidelines. Molecular experiments included redox parameters, DNA fragmentation, Krebs cycle metabolites, and gene expression by RT-PCR/Western blot/LC-MS, PPI (STRING), Pearson correlation, and ROC curve analysis. Here, our findings show that p210/p190BCR/ABL1 translocation is common in all blast crisis phases of CML. Redox factor/Krebs oncometabolite concentrations were high, leading to upregulation and stabilization of HIF1α. HIF1α leads to the pathogenesis in CML cells by upregulating their downstream genes (Notch 2/4/Ikaros/SIRT1/Foxo-3a/p53, etc.). Whereas, downregulated ubiquitin proteasomal and apoptotic factors in CML pateints, can trigger degradation of HIF1α through proline hydroxylation. However, HIF1α showed a negative corelation with the notch1 pathway. Notch1 plays a tumor-suppressive role in CML and might have the potential to be used as a diagnostic marker along with other factors in CML patients. The outcome also revealed that oxidant treatment could not be effective in augmentation with conventional therapy because CML cells can enhance the levels of antioxidants for their survival. HIF1α might be a novel therapeutic target other than BCR/ABL1 translocation.

Design, Synthesis, and Antileukemic Evaluation of a Novel Mikanolide Derivative Through the Ras/Raf/MEK/ERK Pathway

Chronic myeloid leukemia (CML) accounts for a major cause of death in adult leukemia patients due to mutations or other reasons for dysfunction in the ABL proto-oncogene. The ubiquitous BCR–ABL expression stimulates CML by activating CDK1 and cyclin B1, promoting pro-apoptotic, and inhibiting antiapoptotic marker expression along with regulations in RAS pathway activation. Thus, inhibitors of cyclins and the RAS pathway by ERK are of great interest in antileukemic treatments. Mikanolide is a sesquiterpene dilactone isolated from several Asteraceae family Mikania sp. plants. Sesquiterpene dilactone is a traditional medicine for treating ailments, such as flu, cardiovascular diseases, bacterial infections, and other blood disorders. It is used as a cytotoxic agent as well. The need of the hour is potent chemotherapeutic agents with cytotoxic effects inhibition of proliferation and activation of apoptotic machinery. Recently, ERK inhibitors are used in clinics as anticancer agents. Thus, in this study, we synthesized 22-mikanolide derivatives that elucidated to be potent antileukemic agents in vitro. However, a bioactive mikanolide derivative, 3g, was found with potent antileukemic activity, through the Ras/Raf/MEK/ERK pathway. It can arrest the cell cycle by inhibiting phosphorylation of CDC25C, triggering apoptosis, and promoting DNA and mitochondrial damage, thus suggesting it as a potential chemotherapeutic agent for leukemia patients.

Overcoming Cancer Drug Resistance Utilizing PROTAC Technology

Cancer drug resistance presents a major barrier to continued successful treatment of malignancies. Current therapies inhibiting proteins indicated in cancer progression are consistently found to lose efficacy as a result of acquired drug resistance, often caused by mutated or overexpressed protein targets. By hijacking the cellular ubiquitin-proteasome protein degradation machinery, proteolysis-targeting chimeras (PROTACs) offer an alternative therapeutic modality to cancer treatments with various potential advantages. PROTACs specific for a number of known cancer targets have been developed in the last 5 years, which present new options for remission in patients with previously untreatable malignancies and provide a foundation for future-generation compounds. One notable advantage of PROTACs, supported by evidence from a number of recent studies, is that they can overcome some of the resistance mechanisms to traditional targeted therapies. More recently, some groups have begun researching the use of PROTACs to successfully degrade mutated targets conferring cancer resistance against first-line treatments. In this review, we focus on analyzing the developments in PROTACs geared towards cancer resistance and targets that confer it in the search for new and successful therapies.

Combining callers improves the detection of copy number variants from whole-genome sequencing

Copy Number Variants (CNVs) are deletions, duplications or insertions larger than 50 base pairs. They account for a large percentage of the normal genome variation and play major roles in human pathology. While array-based approaches have long been used to detect them in clinical practice, whole-genome sequencing (WGS) bears the promise to allow concomitant exploration of CNVs and smaller variants. However, accurately calling CNVs from WGS remains a difficult computational task, for which a consensus is still lacking. In this paper, we explore practical calling options to reach the best compromise between sensitivity and sensibility. We show that callers based on different signal (paired-end reads, split reads, coverage depth) yield complementary results. We suggest approaches combining four selected callers (Manta, Delly, ERDS, CNVnator) and a regenotyping tool (SV2), and show that this is applicable in everyday practice in terms of computation time and further interpretation. We demonstrate the superiority of these approaches over array-based Comparative Genomic Hybridization (aCGH), specifically regarding the lack of resolution in breakpoint definition and the detection of potentially relevant CNVs. Finally, we confirm our results on the NA12878 benchmark genome, as well as one clinically validated sample. In conclusion, we suggest that WGS constitutes a timely and economically valid alternative to the combination of aCGH and whole-exome sequencing.

Clonal Expansion of Stem/Progenitor Cells in Cancer, Fibrotic Diseases, and Atherosclerosis, and CD47 Protection of Pathogenic Cells

We proposed and demonstrated that myelogenous leukemia has a preleukemic phase. In the premalignant phase, normal hematopoietic stem cells (HSCs) gradually accumulate mutations leading to HSC clonal expansion, resulting in the emergence of leukemic stem cells (LSCs). Here, we show that preleukemic HSCs are the basis of clonal hematopoiesis, as well as late-onset blood diseases (chronic-phase chronic myeloid leukemia, myeloproliferative neoplasms, and myelodysplastic disease). The clones at some point each trigger surface expression of "eat me" signals for macrophages, and in the clones and their LSC progeny, this is countered by upregulation of "don't eat me" signals for macrophages such as CD47,opening the possibility of CD47-based therapies. We include evidence that similar processes result in fibroblast expansion in a variety of fibrotic diseases, and arterial smooth muscle clonal expansion is a basis of atherosclerosis, including upregulation of both "eat me" and "don't eat me" molecules on the pathogenic cells.

Wholistic approach - transcriptomic analysis and beyond using archival material for molecular diagnosis

Many neoplasms remain unclassified after histopathological examination, which requires further molecular analysis. To this regard, mesenchymal neoplasms are particularly challenging due to the combination of their rarity and the large number of subtypes, and many entities still lack robust diagnostic hallmarks. RNA transcriptomic profiles have proven to be a reliable basis for the classification of previously unclassified tumors and notably for mesenchymal neoplasms. Using exome-based RNA capture sequencing on more than 5000 samples of archival material (FFPE), the combination of expression profiles analyzes (including several clustering methods), fusion genes, and small nucleotide variations has been developed at the Centre Léon Bérard (CLB) in Lyon for the molecular diagnosis of challenging neoplasms and the discovery of new entities. The molecular basis of the technique, the protocol, and the bioinformatics algorithms used are described herein, as well as its advantages and limitations.

2-Methoxyestradiol combined with ascorbic acid facilitates the apoptosis of chronic myeloid leukemia cells via the microRNA-223/Fms-like tyrosine kinase 3/phosphatidylinositol-3 kinase/protein kinase B axis

Chronic myeloid leukemia (CML) is a malignant myeloproliferative tumor. 2-Methoxyestradiol (2-ME) is an endogenous estrogen metabolite that shows efficacy in human malignancies. Ascorbic acid (AA) possesses antioxidant activity. This study explored the mechanism of 2-ME combined with AA in the apoptosis of CML cells. Firstly, human CML cell lines were treated with 2-ME and AA. The cell viability, apoptosis, reactive oxygen species (ROS), and mitochondrial membrane potential (MMP) were detected. miR-223 expression in CML cells was detected. In addition, CML cells were transfected with miR-223 inhibitor. The binding relationship between miR-223 and FLT3 was verified. Subsequently, the FLT3 was overexpressed or silenced for the function rescue experiment to confirm the role of FLT3 in CML cell apoptosis. The expression levels of key factors of the PI3K/AKT pathway were detected. Finally, xenograft nude mouse models were established for in vivo verification. 2-ME + AA treatment inhibited CML cell viability and promoted apoptosis, elevated ROS content, and reduced MMP. 2-ME + AA treatment promoted miR-223 expression in CML cells. miR-223 targeted FLT3. Moreover, miR-223 inhibitor or FLT3 overexpression partially annulled the effect of 2-ME + AA on CML cells. 2-ME + AA inhibited the PI3K/AKT pathway via the miR-223/FLT3 axis. Furthermore, 2-ME + AA suppressed CML xenograft growth in mice. Collectively, 2-ME + AA promoted miR-223 expression and suppressed FLT3 and the PI3K/AKT pathway, thereby facilitating the apoptosis of CML cells and inhibiting CML xenograft growth in mice.

Molecular modeling piloted analysis for semicarbazone derivative of curcumin as a potent Abl-kinase inhibitor targeting colon cancer

The human Abl kinases comprise a family of proteins that are known to be key stimulus drivers in the signaling pathways modulating cell growth, cell survival, cell adhesion, and apoptosis. Recent collative studies have indicated the role of activation of Abl and Abl-related genes in solid tumors; further terming the Abl kinases as molecular switches which promote proliferation, tumorigenesis, and metastasis. The up-regulated Abl-kinase expression in colorectal cancer (CRC) and the role of Abl tyrosine kinase activity in the Matrigel invasion of CRC cells have cemented its significance in CRC advancement. Therefore, the requisite of identifying small molecules which serve as Abl selective inhibitors and designing anti-Abl therapies, particularly for CRC tumors, has driven this study. Curcumin has been touted as an effective inhibitor of cancer cells; however, it is limited by its physicochemical inadequacies. Hence, we have studied the behavior of heterocyclic derivatives of curcumin via computational tools such as pharmacophore-based virtual screening, molecular docking, free-energy binding, and ADME profiling. The most actively docked molecule, 3,5-bis(4-hydroxy-3-methylstyryl)-1H-pyrazole-1-carboxamide, was comparatively evaluated against Curcumin via molecular dynamics simulation using Desmond, Schrödinger. The study exhibited the improved stability of the derivative as compared to Curcumin in the tested protein pocket and displayed the interaction bonds with the contacted key amino acids. To further establish the claim, the derivatives were synthesized via the mechanism of cyclization of Curcumin and screened in vitro using SRB assay against human CRC cell line, HCT 116. The active derivative indicated an IC₅₀ value of 5.85 µM, which was sevenfold lower as compared to Curcumin’s IC₅₀ of 35.40 µM. Hence, the results base the potential role of the curcumin derivative in modulating Abl-kinase activity and in turn may have potential therapeutic value as a lead for CRC therapy.

HUGO Gene Nomenclature Committee (HGNC) recommendations for the designation of gene fusions

Gene fusions have been discussed in the scientific literature since they were first detected in cancer cells in the early 1980s. There is currently no standardized way to denote the genes involved in fusions, but in the majority of publications the gene symbols in question are listed either separated by a hyphen (-) or by a forward slash (/). Both types of designation suffer from important shortcomings. HGNC has worked with the scientific community to determine a new, instantly recognizable and unique separator-a double colon (::)-to be used in the description of fusion genes, and advocates its usage in all databases and articles describing gene fusions.

Trends in kinase drug discovery: targets, indications and inhibitor design

The FDA approval of imatinib in 2001 was a breakthrough in molecularly targeted cancer therapy and heralded the emergence of kinase inhibitors as a key drug class in the oncology area and beyond. Twenty years on, this article analyses the landscape of approved and investigational therapies that target kinases and trends within it, including the most popular targets of kinase inhibitors and their expanding range of indications. There are currently 71 small-molecule kinase inhibitors (SMKIs) approved by the FDA and an additional 16 SMKIs approved by other regulatory agencies. Although oncology is still the predominant area for their application, there have been important approvals for indications such as rheumatoid arthritis, and one-third of the SMKIs in clinical development address disorders beyond oncology. Information on clinical trials of SMKIs reveals that approximately 110 novel kinases are currently being explored as targets, which together with the approximately 45 targets of approved kinase inhibitors represent only about 30% of the human kinome, indicating that there are still substantial unexplored opportunities for this drug class. We also discuss trends in kinase inhibitor design, including the development of allosteric and covalent inhibitors, bifunctional inhibitors and chemical degraders.

RhoGTPase Signalling in Cancer Progression and Dissemination

Rho GTPases are a family of small G proteins that regulate a wide array of cellular processes related to their key roles controlling the cytoskeleton. On the other hand, cancer is a multi-step disease caused by the accumulation of genetic mutations and epigenetic alterations, from the initial stages of cancer development when cells in normal tissues undergo transformation, to the acquisition of invasive and metastatic traits, responsible for a large number of cancer related deaths. In this review, we discuss the role of Rho GTPase signalling in cancer in every step of disease progression. Rho GTPases contribute to tumour initiation and progression, by regulating proliferation and apoptosis, but also metabolism, senescence and cell stemness. Rho GTPases play a major role in cell migration, and in the metastatic process. They are also involved in interactions with the tumour microenvironment and regulate inflammation, contributing to cancer progression. After years of intensive research, we highlight the importance of relevant models in the Rho GTPase field, and we reflect on the therapeutic opportunities arising for cancer patients.

Intracellular delivery of anti-BCR/ABL antibody by PLGA nanoparticles suppresses the oncogenesis of chronic myeloid leukemia cells

BACKGROUND

The pathogenesis of chronic myeloid leukemia (CML) is the formation of the BCR/ABL protein, which is encoded by the bcr/abl fusion gene, possessing abnormal tyrosine kinase activity. Despite the wide application of tyrosine kinase inhibitors (TKIs) in CML treatment, TKIs drug resistance or intolerance limits their further usage in a subset of patients. Furthermore, TKIs inhibit the tyrosine kinase activity of the BCR/ABL oncoprotein while failing to eliminate the pathologenic oncoprotein. To develop alternative strategies for CML treatment using therapeutic antibodies, and to address the issue that antibodies cannot pass through cell membranes, we have established a novel intracellular delivery of anti-BCR/ABL antibodies, which serves as a prerequisite for CML therapy.

METHODS

Anti-BCR/ABL antibodies were encapsulated in poly(D, L-lactide-co-glycolide) nanoparticles (PLGA NPs) by a double emulsion method, and transferrin was labeled on the surface of the nanoparticles (Ab@Tf-Cou6-PLGA NPs). The characteristics of nanoparticles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Cellular uptake of nanoparticles was measured by flow cytometry (FCM). The effect of nanoparticles on the apoptosis and proliferation of CML cells was testified by FCM and CCK-8 assay. In addition, the anti-cancer impact of nanoparticles was evaluated in mouse models of CML.

RESULTS

The results demonstrated that the Ab@Tf-Cou6-PLGA NPs functioned as an intracellular deliverer of antibodies, and exhibited an excellent effect on degrading BCR/ABL oncoprotein in CML cells via the Trim-Away pathway. Treatment with Ab@Tf-Cou6-PLGA NPs inhibited the proliferation and induced the apoptosis of CML cells in vitro as well as impaired the oncogenesis ability of CML cells in vivo.

CONCLUSIONS

In conclusion, our study indicated that this approach achieved safe and efficient intracellular delivery of antibodies and degraded BCR/ABL oncoprotein via the Trim-Away pathway, which provides a promising therapeutic strategy for CML patients, particularly those with TKI resistance.

CRISPR-Cas9 Technology as a Tool to Target Gene Drivers in Cancer: Proof of Concept and New Opportunities to Treat Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a hematopoietic malignancy produced by a unique oncogenic event involving the constitutively active tyrosine-kinase (TK) BCR/ABL1. TK inhibitors (TKI) changed its prognosis and natural history. Unfortunately, ABL1 remains unaffected by TKIs. Leukemic stem cells (LSCs) remain, and resistant mutations arise during treatment. To address this problem, we have designed a therapeutic CRISPR-Cas9 deletion system targeting BCR/ABL1. The system was efficiently electroporated to cell lines, LSCs from a CML murine model, and LSCs from CML patients at diagnosis, generating a specific ABL1 null mutation at high efficiency and allowing the edited leukemic cells to be detected and tracked. The CRISPR-Cas9 deletion system triggered cell proliferation arrest and apoptosis in murine and human CML cell lines. Patient and murine-derived xenografts with CRISPR-edited LSCs in NOD SCID gamma niches revealed that normal multipotency and repopulation ability of CRISPR edited LSCs were fully restored. Normal hematopoiesis was restored, avoiding myeloid bias. To the best of our knowledge, we show for the first time how a CRISPR-Cas9 deletion system efficiently interrupts BCR/ABL1 oncogene in primary LSCs to bestow a therapeutic benefit. This study is a proof of concept for genome editing in all those diseases, like CML, sustained by a single oncogenic event, opening up new therapeutic opportunities.

Role of the ABL tyrosine kinases in the epithelial-mesenchymal transition and the metastatic cascade

The ABL kinases, ABL1 and ABL2, promote tumor progression and metastasis in various solid tumors. Recent reports have shown that ABL kinases have increased expression and/or activity in solid tumors and that ABL inactivation impairs metastasis. The therapeutic effects of ABL inactivation are due in part to ABL-dependent regulation of diverse cellular processes related to the epithelial to mesenchymal transition and subsequent steps in the metastatic cascade. ABL kinases target multiple signaling pathways required for promoting one or more steps in the metastatic cascade. These findings highlight the potential utility of specific ABL kinase inhibitors as a novel treatment paradigm for patients with advanced metastatic disease. Video abstract.

c-Abl kinase regulates cell proliferation and ionizing radiation-induced G2/M arrest via phosphorylation of FHL2

Nonreceptor tyrosine kinase c‐Abl participates in several cellular processes by phosphorylating transcription factors or cofactors. c‐Abl binds and phosphorylates four‐and‐a‐half‐LIM‐only protein 2 (FHL2), but the identity of the phosphorylation sites and their contribution to cell cycle regulation is unclear. In this study, we demonstrate that c‐Abl highly phosphorylates FHL2 at Y97, Y176, Y217, and Y236 through mass spectrometry and tyrosine‐to‐phenylalanine (Y → F) mutant analysis. Proliferation was inhibited in cells expressing wild‐type (WT) FHL2 but not cells expressing the phosphorylation‐defective mutant FHL2(4YF). Moreover, FHL2 contributed to cell cycle arrest at G2/M induced by ionizing radiation (IR). FHL2 WT but not FHL2(4YF) rescued FHL2 function in FHL2‐depleted cells by causing IR‐induced G2/M arrest. These results demonstrate that c‐Abl regulates cell cycle progression by phosphorylating FHL2.

Combination Therapies in Chronic Myeloid Leukemia for Potential Treatment-Free Remission: Focus on Leukemia Stem Cells and Immune Modulation

Although tyrosine Kinase Inhibitors (TKI) has revolutionized the treatment of chronic myeloid leukemia (CML), patients are not cured with the current therapy modalities. Also, the more recent goal of CML treatment is to induce successful treatment-free remission (TFR) among patients achieving durable deep molecular response (DMR). Together, it is necessary to develop novel, curative treatment strategies. With advancements in understanding the biology of CML, such as dormant Leukemic Stem Cells (LSCs) and impaired immune modulation, a number of agents are now under investigation. This review updates such agents that target LSCs, and together with TKIs, have the potential to eradicate CML. Moreover, we describe the developing immunotherapy for controlling CML.

Precision medicine in myeloid malignancies

Myeloid malignancies have always been at the forefront of an improved understanding of the molecular pathogenesis of cancer. In accordance, over the last years, basic research focusing on the aberrations underlying malignant transformation of myeloid cells has provided the basis for precision medicine approaches and subsequently has led to the development of powerful therapeutic strategies. In this review article, we will recapitulate what has happened since in the 1980s the use of all-trans retinoic acid (ATRA), as a first targeted cancer therapy, has changed one of the deadliest leukemia subtypes, acute promyelocytic leukemia (APL), into one that can be cured without classical chemotherapy today. Similarly, imatinib, the first molecularly designed cancer therapy, has revolutionized the management of chronic myeloid leukemia (CML). Thus, targeted treatment approaches have become the paradigm for myeloid malignancy, but many questions still remain unanswered, especially how identical mutations can be associated with different phenotypes. This might be linked to the impact of the cell of origin, gene-gene interactions, or the tumor microenvironment including the immune system. Continuous research in the field of myeloid neoplasia has started to unravel the molecular pathways that are not only crucial for initial treatment response, but also resistance of leukemia cells under therapy. Ongoing studies focusing on leukemia cell vulnerabilities do already point to novel (targetable) "Achilles heels" that can further improve myeloid cancer therapy.

Higher red blood cell distribution width at diagnose is a simple negative prognostic factor in chronic phase-chronic myeloid leukemia patients treated with tyrosine kinase inhibitors: A retrospective study

The aim of this study was to evaluate the ability of the red blood cell distribution width (RDW) to predict prognosis and treatment response in chronic myeloid leukemia (CML)-chronic phase (CP) patients treated with tyrosine kinase inhibitor (TKIs).We retrospectively enrolled 93 newly diagnosed CML-CP patients treated with TKIs from 2009 to 2018 at the First Hospital of Lanzhou University. Patients were divided into 2 groups using an RDW of 18.65% determined by receiver operating characteristic curve analysis. We analyzed the correlation of treatment responses and the RDW compared to common scoring systems, as well as the correlation of the RDW with disease outcome, including overall survival (OS) and progression-free survival (PFS), and demographic and laboratory factors affecting outcome. Univariate analysis and Cox regression analysis were used.The median age of patients was 40 years, and 51 patients (54.8%) were men. A high RDW could predict treatment response at 3 months (P = .03) and 6 months (P = .02). The RDW was significantly lower in patients who achieved molecular response by 3 months (P < .001) and complete cytogenetic response by 6 months (P = .001) than in those who did not respond. Patients with a high RDW (>18.65%, n = 35) had significantly worse 5-year OS (77.1% vs 96.6%; P = .008) and PFS (80.0% vs 98.3%; P = .002) than those with a low RDW (≤18.65%, n = 58). Multivariate analysis demonstrated that a high RDW was an adverse predictor of OS (P = .005, HR (hazard ratio) = 9.741) and PFS (P = .009, HR = 16.735).The RDW is a readily available prognostic marker of outcome in patients with CML-CP and can predict treatment response to TKIs. Further larger and prospective studies are required.

The application of BH3 mimetics in myeloid leukemias

Execution of the intrinsic apoptotic pathway is controlled by the BCL-2 proteins at the level of the mitochondrial outer membrane (MOM). This family of proteins consists of prosurvival (e.g., BCL-2, MCL-1) and proapoptotic (e.g., BIM, BAD, HRK) members, the functional balance of which dictates the activation of BAX and BAK. Once activated, BAX/BAK form pores in the MOM, resulting in cytochrome c release from the mitochondrial intermembrane space, leading to apoptosome formation, caspase activation, and cleavage of intracellular targets. This pathway is induced by cellular stress including DNA damage, cytokine and growth factor withdrawal, and chemotherapy/drug treatment. A well-documented defense of leukemia cells is to shift the balance of the BCL-2 family in favor of the prosurvival proteins to protect against such intra- and extracellular stimuli. Small molecule inhibitors targeting the prosurvival proteins, named 'BH3 mimetics', have come to the fore in recent years to treat hematological malignancies, both as single agents and in combination with standard-of-care therapies. The most significant example of these is the BCL-2-specific inhibitor venetoclax, given in combination with standard-of-care therapies with great success in AML in clinical trials. As the number and variety of available BH3 mimetics increases, and investigations into applying these novel inhibitors to treat myeloid leukemias continue apace the need to evaluate where we currently stand in this rapidly expanding field is clear.

Inhibition of cystathionine β-synthase promotes apoptosis and reduces cell proliferation in chronic myeloid leukemia

Increased endogenous hydrogen sulfide (H₂S) level by cystathionine β-synthase (CBS) has been shown to closely relate tumorigenesis. H₂S promotes angiogenesis, stimulates bioenergy metabolism and inhibits selective phosphatases. However, the role of CBS and H₂S in chronic myeloid leukemia (CML) remains elusive. In this study, we found that CBS and H₂S levels were increased in the bone marrow mononuclear cells of pediatric CML patients, as well as in the CML-derived K562 cells and CBS expression levels were correlated with different disease phases. Inhibition of CBS reduced the proliferation of the CML primary bone marrow mononuclear cells and induced growth inhibition, apoptosis, cell cycle arrest, and migration suppression in K562 cells and tumor xenografts. The knockdown of CBS expression by shRNA and inhibiting CBS activity by AOAA decreased the endogenous H₂S levels, promoted mitochondrial-related apoptosis and inhibited the NF-κB-mediated gene expression. Our study suggests that inhibition of CBS induces cell apoptosis, as well as limits cell proliferation and migration, a potential target for the treatment of chronic myeloid leukemia.

Future Approaches for Treating Chronic Myeloid Leukemia: CRISPR Therapy

Simple Summary

In the last two decades, the therapeutic landscape of several tumors have changed profoundly with the introduction of drugs against proteins encoded by oncogenes. Oncogenes play an essential role in human cancer and when their encoded proteins are inhibited by specific drugs, the tumoral process can be reverted or stopped. An example of this is the case of the chronic myeloid leukemia, in which all the pathological features can be attributed by a single oncogene. Most patients with this disease now have a normal life expectancy thanks to a rationality designed inhibitor. However, the drug only blocks the protein, the oncogene continues unaffected and treatment discontinuation is only an option for a small subset of patients. With the advent of genome-editing nucleases and, especially, the CRISPR/Cas9 system, the possibilities to destroy oncogenes now is feasible. A novel therapeutic tool has been developed with unimaginable limits in cancer treatment. Recent studies support that CRISPR/Cas9 system could be a definitive therapeutic option in chronic myeloid leukemia. This work reviews the biology of chronic myeloid leukemia, the emergence of the CRISPR system, and its ability as a specific tool for this disease.

Abstract

The constitutively active tyrosine-kinase BCR/ABL1 oncogene plays a key role in human chronic myeloid leukemia development and disease maintenance, and determines most of the features of this leukemia. For this reason, tyrosine-kinase inhibitors are the first-line treatment, offering most patients a life expectancy like that of an equivalent healthy person. However, since the oncogene stays intact, lifelong oral medication is essential, even though this triggers adverse effects in many patients. Furthermore, leukemic stem cells remain quiescent and resistance is observed in approximately 25% of patients. Thus, new therapeutic alternatives are still needed. In this scenario, the interruption/deletion of the oncogenic sequence might be an effective therapeutic option. The emergence of CRISPR (clustered regularly interspaced short palindromic repeats) technology can offer a definitive treatment based on its capacity to induce a specific DNA double strand break. Besides, it has the advantage of providing complete and permanent oncogene knockout, while tyrosine kinase inhibitors (TKIs) only ensure that BCR-ABL1 oncoprotein is inactivated during treatment. CRISPR/Cas9 cuts DNA in a sequence-specific manner making it possible to turn oncogenes off in a way that was not previously feasible in humans. This review describes chronic myeloid leukemia (CML) disease and the main advances in the genome-editing field by which it may be treated in the future.

Chronic Myeloid Leukemia: A Model Disease of the Past, Present and Future

Chronic myeloid leukemia (CML) has been a "model disease" with a long history. Beginning with the first discovery of leukemia and the description of the Philadelphia Chromosome and ending with the current goal of achieving treatment-free remission after targeted therapies, we describe here the journey of CML, focusing on molecular pathways relating to signaling, metabolism and the bone marrow microenvironment. We highlight current strategies for combination therapies aimed at eradicating the CML stem cell; hopefully the final destination of this long voyage.

Mouse Models of Myeloid Malignancies

Mouse models of human myeloid malignancies support the detailed and focused investigation of selected driver mutations and represent powerful tools in the study of these diseases. Carefully developed murine models can closely recapitulate human myeloid malignancies in vivo, enabling the interrogation of a number of aspects of these diseases including their preclinical course, interactions with the microenvironment, effects of pharmacological agents, and the role of non-cell-autonomous factors, as well as the synergy between co-occurring mutations. Importantly, advances in gene-editing technologies, particularly CRISPR-Cas9, have opened new avenues for the development and study of genetically modified mice and also enable the direct modification of mouse and human hematopoietic cells. In this review we provide a concise overview of some of the important mouse models that have advanced our understanding of myeloid leukemogenesis with an emphasis on models relevant to clonal hematopoiesis, myelodysplastic syndromes, and acute myeloid leukemia with a normal karyotype.

Molecular docking and pharmacophoric modelling of 1,5-disubstituted tetrazoles as inhibitors of two proteins present in cancer, the ABL and the mutated T315I kinase

A docking study of a set of several 1,5-disubstituted tetrazoles compounds has been performed to predict the poses of some potential inhibitors of the Abelson tyrosine-protein kinase and the mutated Abelson tyrosine-protein kinase T315I. The study was conducted through Lamarckian genetic algorithms in Autodock4 package. Bayesian calculations were performed; specificity and sensitivity values as well as positive predicted values, and negative predicted values were calculated using a set of 99 known experimentally active ligands and 385 decoys for the Abelson tyrosine-protein kinase from the Directory of Useful Decoys database. Root mean square deviation values were calculated though the X-ray crystallographic data of the bioactive pose of imatinib as reference, and the pose obtained with the above methods. The obtained results show the importance of the protein interactions with the halogens present in some of these 1,5-disubstituted tetrazoles ligands, as well as the presence of some hydrophobic fragments, obtained via the pharmacophoric model, concluding that the eight novels 1,5-disubstituted tetrazoles compounds herein identified, could be effective inhibitors of Abelson tyrosine-protein kinase, using a docking calculations.

Identification of novel fusion transcripts in meningioma

INTRODUCTION

Meningiomas are the most common primary intracranial tumor. Recent next generation sequencing analyses have elaborated the molecular drivers of this disease. We aimed to identify and characterize novel fusion genes in meningiomas.

METHODS

We performed a secondary analysis of our RNA sequencing data of 145 primary meningioma from 140 patients to detect fusion genes. Semi-quantitative rt-PCR was performed to confirm transcription of the fusion genes in the original tumors. Whole exome sequencing was performed to identify copy number variations within each tumor sample. Comparative RNA seq analysis was performed to assess the clonality of the fusion constructs within the tumor.

RESULTS

We detected six fusion events (NOTCH3-SETBP1, NF2-SPATA13, SLC6A3-AGBL3, PHF19-FOXP2 in two patients, and ITPK1-FBP2) in five out of 145 tumor samples. All but one event (NF2-SPATA13) led to extremely short reading frames, making these events de facto null alleles. Three of the five patients had a history of childhood radiation. Four out of six fusion events were detected in expression type C tumors, which represent the most aggressive meningioma. We validated the presence of the RNA transcripts in the tumor tissue by semi-quantitative RT PCR. All but the two PHF19-FOXP2 fusions demonstrated high degrees of clonality.

CONCLUSIONS

Fusion genes occur infrequently in meningiomas and are more likely to be found in tumors with greater degree of genomic instability (expression type C) or in patients with history of cranial irradiation.

Ponatinib and other CML Tyrosine Kinase Inhibitors in Thrombosis

Abl1 kinase has important biological roles. The Bcr-Abl1 fusion protein creates undesired kinase activity and is pathogenic in 95% of chronic myeloid leukemia (CML) and 30% of acute lymphoblastic leukemia (ALL) patients. Targeted therapies to these diseases are tyrosine kinase inhibitors. The extent of a tyrosine kinase inhibitor’s targets determines the degree of biologic effects of the agent that may influence the well-being of the patient. This fact is especially true with tyrosine kinase inhibitor effects on the cardiovascular system. Thirty-one percent of ponatinib-treated patients, the tyrosine kinase inhibitor with the broadest inhibitory spectrum, have thrombosis associated with its use. Recent experimental investigations have indicated the mechanisms of ponatinib-associated thrombosis. Further, an antidote to ponatinib is in development by re-purposing an FDA-approved medication.

Efficacy of tyrosine kinase inhibitors on a mouse chronic myeloid leukemia model and chronic myeloid leukemia stem cells

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder caused by constitutively active BCR-ABL1 tyrosine kinase resulting from the t(9;22) Philadelphia translocation. Imatinib, a BCR-ABL1 tyrosine kinase inhibitor (TKI), is a revolutionary molecular target inhibitor for CML. However, leukemic stem cells (LSCs) eventually become resistant to imatinib and thereby cause relapse. The next-generation BCR-ABL1 TKI dasatinib is also unable to eliminate CML LSCs. On the other hand, the third-generation BCR-ABL1 TKI ponatinib is not well studied in terms of its efficacy on CML LSCs. Here, we evaluate the efficacy of ponatinib against CML LSC-containing lin^-Sca-1⁺c-Kit⁺ (LSK) cells using a mouse CML-like model. To this end, we compared the efficacy of imatinib, dasatinib, and ponatinib on CML LSK cells and showed that ponatinib is more effective at eliminating CML LSK cells. Our results suggest that ponatinib could be potentially useful for achieving treatment-free remission in CML patients.

Cardiotoxicity of the BCR-ABL1 tyrosine kinase inhibitors: Emphasis on ponatinib

The advent of tyrosine kinase inhibitors (TKIs) targeted therapy revolutionized the treatment of chronic myeloid leukemia (CML) patients. However, cardiotoxicity associated with these targeted therapies puts the cancer survivors at higher risk. Ponatinib is a third-generation TKI for the treatment of CML patients having gatekeeper mutation T315I, which is resistant to the first and second generation of TKIs, namely, imatinib, nilotinib, dasatinib, and bosutinib. Multiple unbiased screening from our lab and others have identified ponatinib as most cardiotoxic FDA approved TKI among the entire FDA approved TKI family (total 50+). Indeed, ponatinib is the only treatment option for CML patients with T315I mutation. This review focusses on the cardiovascular risks and mechanism/s associated with CML TKIs with a particular focus on ponatinib cardiotoxicity. We have summarized our recent findings with transgenic zebrafish line harboring BNP luciferase activity to demonstrate the cardiotoxic potential of ponatinib. Additionally, we will review the recent discoveries reported by our and other laboratories that ponatinib primarily exerts its cardiotoxicity via an off-target effect on cardiomyocyte prosurvival signaling pathways, AKT and ERK. Finally, we will shed light on future directions for minimizing the adverse sequelae associated with CML-TKIs.