Clonal evolution with inv(11)(p15q22) and NUP98/DDX10 fusion gene in imatinib-resistant chronic myelogenous leukemia

UTP14A, DKC1, DDX10, PinX1, and ESF1 Modulate Cardiac Angiogenesis Leading to Obesity-Induced Cardiac Injury

BACKGROUND

This study is aimed at exploring the key genes and the possible mechanism of heart damage caused by obesity.

METHODS

We analyzed the GSE98226 dataset. Firstly, differentially expressed genes (DEGs) were identified in heart tissues of obese and normal mice. Then, we analyzed DEGs using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Thirdly, we constructed a protein-protein interaction (PPI) network and key modules and searched hub genes. Finally, we observed the pathological changes associated with obesity through histopathology.

RESULTS

A total of 763 DEGs were discovered, including 629 upregulated and 134 downregulated genes. GO enrichment analysis showed that these DEGs were mainly related to the regulation of transcription, DNA-templated, nucleic acid binding, and metal ion binding. KEGG pathway analysis revealed that the DEGs were enriched in long-term depression, gap junction, and sphingolipid signaling pathways. Finally, we identified UTP14A, DKC1, DDX10, PinX1, and ESF1 as the hub genes. Histopathologic analysis showed that obesity increased the number of collagen fibers and decreased the number of microvessels and proliferation of the endothelium and increased endothelial cell damage which further leads to dysfunction of cardiac microcirculation.

CONCLUSION

UTP14A, DKC1, DDX10, PinX1, and ESF1 have been identified as hub genes in obesity-induced pathological changes in the heart and may be involved in obesity-induced cardiac injury by affecting cardiac microcirculatory function.

The DEAD-box protein family of RNA helicases: sentinels for a myriad of cellular functions with emerging roles in tumorigenesis

DEAD-box RNA helicases comprise a family within helicase superfamily 2 and make up the largest group of RNA helicases. They are a profoundly conserved family of RNA-binding proteins, carrying a generic Asp-Glu-Ala-Asp (D-E-A-D) motif that gives the family its name. Members of the DEAD-box family of RNA helicases are engaged in all facets of RNA metabolism from biogenesis to decay. DEAD-box proteins ordinarily function as constituents of enormous multi-protein complexes and it is believed that interactions with other components in the complexes might be answerable for the various capacities ascribed to these proteins. Therefore, their exact function is probably impacted by their interacting partners and to be profoundly context dependent. This may give a clarification to the occasionally inconsistent reports proposing that DEAD-box proteins have both pro- and anti-proliferative functions in cancer. There is emerging evidence that DEAD-box family of RNA helicases play pivotal functions in various cellular processes and in numerous cases have been embroiled in cellular proliferation and/or neoplastic transformation. In various malignancy types, DEAD-box RNA helicases have been reported to possess pro-proliferation or even oncogenic roles as well as anti-proliferative or tumor suppressor functions. Clarifying the exact function of DEAD-box helicases in cancer is probably intricate, and relies upon the cellular milieu and interacting factors. This review aims to summarize the current data on the numerous capacities that have been ascribed to DEAD-box RNA helicases. It also highlights their diverse actions upon malignant transformation in the various tumor types.

Mechanistic insights and potential therapeutic approaches for NUP98-rearranged hematologic malignancies

Nucleoporin 98 (NUP98) fusion oncoproteins are observed in a spectrum of hematologic malignancies, particularly pediatric leukemias with poor patient outcomes. Although wild-type full-length NUP98 is a member of the nuclear pore complex, the chromosomal translocations leading to NUP98 gene fusions involve the intrinsically disordered and N-terminal region of NUP98 with over 30 partner genes. Fusion partners include several genes bearing homeodomains or having known roles in transcriptional or epigenetic regulation. Based on data in both experimental models and patient samples, NUP98 fusion oncoprotein-driven leukemogenesis is mediated by changes in chromatin structure and gene expression. Multiple cofactors associate with NUP98 fusion oncoproteins to mediate transcriptional changes possibly via phase separation, in a manner likely dependent on the fusion partner. NUP98 gene fusions co-occur with a set of additional mutations, including FLT3-internal tandem duplication and other events contributing to increased proliferation. To improve the currently dire outcomes for patients with NUP98-rearranged malignancies, therapeutic strategies have been considered that target transcriptional and epigenetic machinery, cooperating alterations, and signaling or cell-cycle pathways. With the development of more faithful experimental systems and continued study, we anticipate great strides in our understanding of the molecular mechanisms and therapeutic vulnerabilities at play in NUP98-rearranged models. Taken together, these studies should lead to improved clinical outcomes for NUP98-rearranged leukemia.

ETS1 and SP1 drive DHX15 expression in acute lymphoblastic leukaemia

DHX15 plays a role in leukaemogenesis and leukaemia relapse. However, the mechanism underlying the transcriptional regulation of DHX15 in ALL has not been elucidated. Our present study aimed to explore the functional promoter region of DHX15 and to investigate the transcription factors controlling the transcription of this gene. A luciferase assay performed with several truncated constructs identified a 501-bp region as the core promoter region of DHX15. Site-directed mutagenesis, electrophoretic mobility shift and chromatin immunoprecipitation assays showed that ETS1 and SP1 occupied the DHX15 promoter. Furthermore, knockdown of ETS1 and SP1 resulted in suppression of DHX15, whereas the overexpression of these genes led to up-regulation of DHX15. Interestingly, in samples obtained from patients with ALL at diagnosis, both ETS1 and SP1 correlated positively with DHX15 expression. Additionally, differences in methylation of the DHX15 core promoter region were not observed between the patients and controls. In conclusion, we identified the core promoter region of DHX15 and demonstrated that ETS1 and SP1 regulated DHX15 expression in ALL.

Genomic Profiling of Chronic Myelogenous Leukemia: Basic and Clinical Approach

Chronic myeloid leukemia (CML) is a hematological stem cell cancer driven by BCR-ABL1 fusion protein. We review the previous and recent evidence on the significance of CML in diagnostic and clinic management. The technical monitoring of BCR-ABL1 with quantitative real time-PCR has been used in assessing patient outcome. The cytogenetic mark of CML is Philadelphia chromosome, that is formed by reciprocal chromosomal translocations between human chromosome 9 and 22, t(9:22) (q³⁴:q¹¹). It makes a BCR-ABL1 fusion protein with an anomaly tyrosine kinase activity that promotes the characteristic proliferation of progenitor cells in CML and acute lymphoblastic lymphoma. The targeting of BCR-ABL1 fusion kinase is the first novel paradigm of molecularly targeted curing.

Wanted DEAD/H or Alive: Helicases Winding Up in Cancers

Cancer is one of the most studied areas of human biology over the past century. Despite having attracted much attention, hype, and investments, the search to find a cure for cancer remains an uphill battle. Recent discoveries that challenged the central dogma of molecular biology not only further increase the complexity but also demonstrate how various types of noncoding RNAs such as microRNA and long noncoding RNA, as well as their related processes such as RNA editing, are important in regulating gene expression. Parallel to this aspect, an increasing number of reports have focused on a family of proteins known as DEAD/H-box helicases involved in RNA metabolism, regulation of long and short noncoding RNAs, and novel roles as "editing helicases" and their association with cancers. This review summarizes recent findings on the roles of RNA helicases in various cancers, which are broadly classified into adult solid tumors, childhood solid tumors, leukemia, and cancer stem cells. The potential small molecule inhibitors of helicases and their therapeutic value are also discussed. In addition, analyzing next-generation sequencing data obtained from public portals and reviewing existing literature, we provide new insights on the potential of DEAD/H-box helicases to act as pharmacological drug targets in cancers.

Nucleoporin Gene Fusions and Hematopoietic Malignancies

Nuclear pore complexes (NPCs) are the sole gateways between the nucleus and the cytoplasm of eukaryotic cells and they mediate all macromolecular trafficking between these cellular compartments. Nucleocytoplasmic transport is highly selective and precisely regulated and as such an important aspect of normal cellular function. Defects in this process or in its machinery have been linked to various human diseases, including cancer. Nucleoporins, which are about 30 proteins that built up NPCs, are critical players in nucleocytoplasmic transport and have also been shown to be key players in numerous other cellular processes, such as cell cycle control and gene expression regulation. This review will focus on the three nucleoporins Nup98, Nup214, and Nup358. Common to them is their significance in nucleocytoplasmic transport, their multiple other functions, and being targets for chromosomal translocations that lead to haematopoietic malignancies, in particular acute myeloid leukaemia. The underlying molecular mechanisms of nucleoporin-associated leukaemias are only poorly understood but share some characteristics and are distinguished by their poor prognosis and therapy outcome.

Nucleoporins and nucleocytoplasmic transport in hematologic malignancies

Hematologic malignancies are often associated with chromosomal rearrangements that lead to the expression of chimeric fusion proteins. Rearrangements of the genes encoding two nucleoporins, NUP98 and NUP214, have been implicated in the pathogenesis of several types of hematologic malignancies, particularly acute myeloid leukemia. NUP98 rearrangements result in fusion of an N-terminal portion of NUP98 to one of numerous proteins. These rearrangements often follow treatment with topoisomerase II inhibitors and tend to occur in younger patients. They have been shown to induce leukemia in mice and to enhance proliferation and disrupt differentiation in primary human hematopoietic precursors. NUP214 has only a few fusion partners. DEK-NUP214 is the most common NUP214 fusion in AML; it tends to occur in younger patients and is usually associated with FLT3 internal tandem duplications. The leukemogenic activity of NUP214 fusions is less well characterized. Normal nucleoporins, including NUP98 and NUP214, have important functions in nucleocytoplasmic transport, transcription, and mitosis. These functions and their disruptions by oncogenic nucleoporin fusions are discussed.

Inv(11)(p15q22)/NUP98-DDX10 fusion and isoforms in a new case of de novo acute myeloid leukemia

We set up a diagnostic double-color double-fusion fluorescence in situ hybridization (DCDF-FISH) assay to investigate a case of a de novo acute myeloid leukemia (AML)-M4 bearing an inv(11)(p15q22). DCDF-FISH detected the NUP98-DDX10 rearrangement as two fusion signals, at the short and the long arms of the inv(11). Reverse transcription-polymerase chain reaction (RT-PCR) and cloning experiments confirmed the NUP98-DDX10 fusion and identified two splicing fusion isoforms: the known "type II fusion," originating from the fusion of NUP98 exon 14 to DDX10 exon 7 and a new in-frame fusion transcript between NUP98 exon 15 and DDX10 exon 7, which we termed "type III fusion."

Genetic mechanisms of chronic myeloid leukemia blastic transformation

The BCR-ABL1 oncogenic tyrosine kinase can transform pluripotent hematopoietic stem cells and initiate chronic myeloid leukemia in chronic phase (CML-CP), a myeloproliferative disorder characterized by excessive accumulation of mature myeloid cells. Patients in CML-CP usually respond to treatment with ABL1 tyrosine kinase inhibitors (TKIs) such as imatinib, though some patients who respond initially may become resistant later. CML-CP leukemia stem cells (LSCs) are intrinsically insensitive to TKIs and thus survive in the long term. These LSCs or their progeny may at some stage acquire additional genetic changes that cause the leukemia to transform further, from CML-CP to a more advanced phase, which has been subclassified as either accelerated phase (CML-AP) or blastic phase (CML-BP). CML-BP is characterized by a major clonal expansion of immature progenitors, which have either myeloid or lymphoid features. CML-BP responds poorly to treatment and is usually fatal. This review discusses the role of genomic instability leading to blastic transformation of CML and proposes some novel therapeutic approaches.

Amino-terminal enhancer of split (AES) interacts with the oncoprotein NUP98-HOXA9 and enhances its transforming ability

NUP98-HOXA9 is the prototype of NUP98 fusion oncoproteins that cause acute myeloid leukemia. It consists of an N-terminal FG-rich portion of the nucleoporin NUP98 fused to the homeodomain region of the homeobox protein HOXA9, and acts as an aberrant transcription factor. To identify interacting partners of NUP98-HOXA9, we used a cytoplasmic yeast two-hybrid assay to avoid the nonspecific trans-activation that would occur with the traditional yeast two-hybrid assay due to the transactivating properties of NUP98-HOXA9. We identified amino-terminal enhancer of split (AES), a transcriptional regulator of the transducin-like enhancer/Groucho family as a novel interaction partner of NUP98-HOXA9. The interaction was confirmed by in vitro pulldown and co-immunoprecipitation assays and was shown to require the FG repeat region of NUP98-HOXA9. Immunofluorescence analysis showed that AES localizes primarily to the interior of the nucleus. AES also showed a strong interaction with wild-type NUP98. AES augmented the transcriptional activity of NUP98-HOXA9. In the presence of NUP98-HOXA9, AES caused an increase in long-term proliferation of primary human CD34+ cells with a marked increase in the numbers of primitive cells. These effects of AES were not observed in the absence of NUP98-HOXA9. AES knockdown diminished the transcriptional and proliferative effects of NUP98-HOXA9. AES caused a shift away from the erythroid lineage in cells expressing NUP98-HOXA9. These data establish AES as an interacting partner of NUP98-HOXA9 and show that it cooperates with NUP98-HOXA9 in transcriptional regulation and cell transformation.

Chronic myeloid leukemia: mechanisms of blastic transformation

The BCR-ABL1 oncoprotein transforms pluripotent HSCs and initiates chronic myeloid leukemia (CML). Patients with early phase (also known as chronic phase [CP]) disease usually respond to treatment with ABL tyrosine kinase inhibitors (TKIs), although some patients who respond initially later become resistant. In most patients, TKIs reduce the leukemia cell load substantially, but the cells from which the leukemia cells are derived during CP (so-called leukemia stem cells [LSCs]) are intrinsically insensitive to TKIs and survive long term. LSCs or their progeny can acquire additional genetic and/or epigenetic changes that cause the leukemia to transform from CP to a more advanced phase, which has been subclassified as either accelerated phase or blastic phase disease. The latter responds poorly to treatment and is usually fatal. Here, we discuss what is known about the molecular mechanisms leading to blastic transformation of CML and propose some novel therapeutic approaches.

Phase II study of low-dose decitabine in combination with imatinib mesylate in patients with accelerated or myeloid blastic phase of chronic myelogenous leukemia

BACKGROUND

Resistance to imatinib is a frequent clinical problem in advanced phase chronic myelogenous leukemia (CML). A Phase II study was performed on low-dose decitabine, a DNA methyltransferase inhibitor, in combination with imatinib in patients with CML in accelerated phase (AP) and myeloid blastic phase (BP).

METHODS

Patients received decitabine 15 mg/m(2) intravenously daily, 5 days a week for 2 weeks, and imatinib 600 mg orally daily. Global DNA methylation was measured by long interspersed nucleotide element (LINE) bisulfite/pyrosequencing.

RESULTS

Twenty-eight patients were enrolled (25 with imatinib resistance; 18 in AP, 10 in BP). A total of 91 cycles (median, 2.5 cycles per patient) was administered. Complete hematologic responses, partial hematologic responses, and hematologic improvement were observed in 9 (32%), 1 (4%), and 2 (7%) patients. Major and minor cytogenetic responses were observed in 5 (18%) and 3 (11%) patients. The hematologic response rate was higher in patients without BCR-ABL kinase mutations (10 of 19, 53%) than in those with mutations (1 of 7, 14%). Median duration of hematologic response was 18 (range, 4 to 107+) weeks. Myelosuppression was the major adverse effect, with neutropenic fever in 9 patients (32%). LINE methylation decreased from 71.6% +/- 0.9% (mean +/- standard error of the mean) to 60.4% +/- 2.0% on Day 5, 60.5% +/- 1.8% on Day 12, and returned to 68.8% +/- 1.4% at peripheral blood recovery. A decrease in LINE methylation tended to be greater in nonresponders than in responders on Days 5 and 12.

CONCLUSIONS

Combination therapy with decitabine and imatinib is well tolerated and active in advanced phase CML without BCR-ABL kinase mutations.

The chloromethylketone protease inhibitor AAPF(CMK) also targets ATP-dependent helicases and SAP-domain proteins

We have been studying a nuclear protease, which appears to be involved in cellular transformation, as well as in infections with high-risk human papillomaviruses (HPVs). This protease has a chymotrypsin-like substrate specificity and the chloromethylketone inhibitor AAPF(CMK) is a potent (and relatively selective) inhibitor of it. Recently, we have observed that AAPF(CMK) has potent effects in some model systems which appear not to be mediated by decreases in the nuclear protease. Here we show that AAPF(CMK) selectively reacts with ATP-dependent helicases as well as a limited spectrum of proteins in other DNA repair/chromatin remodeling nuclear complexes, including for example Cohesin complex components and proteins containing SAP-domains. In vitro, AAPF(CMK) selectively reacts with SV40 large T antigen, and inhibits its helicase activity.

Role of BCR/ABL gene-expression levels in determining the phenotype and imatinib sensitivity of transformed human hematopoietic cells

Increased levels of Bcr-Abl expression in chronic myelogenous leukemia (CML) cells are associated with disease progression and imatinib (IM) resistance. However, it is not clear if these associations are a direct result of elevated Bcr-Abl expression. We used a human transduction model of CML to directly investigate the role of varying Bcr-Abl expression levels in determining the phenotype and IM sensitivity of hematopoietic cells. CD34(+) cells were transduced with vectors coexpressing Bcr-Abl and GFP, and cells expressing low and high levels of GFP and Bcr-Abl (BA(lo) and BA(hi)) were selected. BA(hi) cells demonstrated enhanced activation of downstream proliferative and antiapoptotic signaling and enhanced proliferation and survival compared to BA(lo) cells. Freshly isolated BA(hi) CD34(+) cells and cell lines demonstrated increased IM-mediated growth inhibition likely reflecting Bcr-Abl dependence for growth and survival. CD34(+) cells expressing BCR/ABL kinase-mutant genes demonstrated resistance to IM-mediated inhibition of proliferation and viability, which was not enhanced by increased expression of BCR/ABL kinase-mutant genes. We conclude that Bcr-Abl overexpression results in increased proliferation and antiapoptotic signaling in CD34(+) cells, but may not play a direct role in IM resistance in progenitor cells expressing either wild-type or mutant BCR/ABL genes.

Inversion (11)(p15q22) with NUP98–DDX10 fusion gene in pediatric acute myeloid leukemia

The inv(11)(p15q22), a rare but recurrent chromosome abnormality that creates a NUP98-DDX10 fusion gene, is associated with de novo or secondary myeloid malignancies. We report a case of acute monocytic leukemia presenting this rearrangement, studied using fluorescence in situ hybridization (FISH) and reverse transcriptase-PCR (RT-PCR). We also review the cases of inv(11) associated with NUP98-DDX10 reported in the literature.

Chronic myeloid leukemia: Standard treatment options

PURPOSE

Treatment options for chronic myeloid leukemia (CML) are discussed.

SUMMARY

In the 1980s busulfan and hydroxyurea were the standards of care. These were subsequently replaced by interferon alpha (IFN alpha) based therapy. Currently, bone marrow transplant survival has improved, making this also a viable option. Five-year progression-free survival averaged above 70% for chemotherapeutic options. Transplant survival at 56 months was approximately 60%; however, these survivors were generally cured of disease. The recognition of the role for BCR-ABL in CML has led to the development of specific kinase inhibitors such as imatinib. Clinical trial evidence has demonstrated a clear superiority of imatinib over interferon plus cytarabine, making this the new standard of care in first-line treatment of CML. Resistance to imatinib has been observed, in addition to relapse. The data suggest that the probability of response may be estimated as early as six months after initiation of imatinib therapy. Although combinations of imatinib with IFN alpha show small improvements compared to imatinib therapy alone, the biggest improvements were seen when imatinib doses were doubled. Unfortunately, not all patients can tolerate this increase in dose. The most common mechanism for imatinib resistance is the presence of a mutated BCR-ABL kinase. Several of these mutants have been cloned and characterized.

CONCLUSION

Molecular-targeted BCR-ABL kinase inhibitors, such as imatinib, are now first-line treatment for CML. Allogeneic stem cell transplant is still the only proven curable treatment for CML in patients with an appropriate donor. Next generation BCR-ABL kinase inhibitors hold promise for patients with mutated BCR-ABL kinase that confer resistance to imatinib.

NUP98 rearrangements in hematopoietic malignancies: a study of the Groupe Francophone de Cytogénétique Hématologique

The NUP98 gene is fused with 19 different partner genes in various human hematopoietic malignancies. In order to gain additional clinico-hematological data and to identify new partners of NUP98, the Groupe Francophone de Cytogénétique Hématologique (GFCH) collected cases of hematological malignancies where a 11p15 rearrangement was detected. Fluorescence in situ hybridization (FISH) analysis showed that 35% of these patients (23/66) carried a rearrangement of the NUP98 locus. Genes of the HOXA cluster and the nuclear-receptor set domain (NSD) genes were frequently fused to NUP98, mainly in de novo myeloid malignancies whereas the DDX10 and TOP1 genes were equally rearranged in de novo and in therapy-related myeloid proliferations. Involvement of ADD3 and C6ORF80 genes were detected, respectively, in myeloid disorders and in T-cell acute lymphoblastic leukemia (T-ALL), whereas the RAP1GDS1 gene was fused to NUP98 in T-ALL. Three new chromosomal breakpoints: 3q22.1, 7p15 (in a localization distinct from the HOXA locus) and Xq28 were detected in rearrangements with the NUP98 gene locus. The present study as well as a review of the 73 cases previously reported in the literature allowed us to delineate some chromosomal, clinical and molecular features of patients carrying a NUP98 gene rearrangements.

Dasatinib in imatinib-resistant Philadelphia chromosome-positive leukemias

BACKGROUND

The BCR-ABL tyrosine kinase inhibitor imatinib is effective in Philadelphia chromosome-positive (Ph-positive) leukemias, but relapse occurs, mainly as a result of the outgrowth of leukemic subclones with imatinib-resistant BCR-ABL mutations. We evaluated dasatinib, a BCR-ABL inhibitor that targets most imatinib-resistant BCR-ABL mutations, in patients with chronic myelogenous leukemia (CML) or Ph-positive acute lymphoblastic leukemia (ALL).

METHODS

Patients with various phases of CML or with Ph-positive ALL who could not tolerate or were resistant to imatinib were enrolled in a phase 1 dose-escalation study. Dasatinib (15 to 240 mg per day) was administered orally in four-week treatment cycles, once or twice daily.

RESULTS

A complete hematologic response was achieved in 37 of 40 patients with chronic-phase CML, and major hematologic responses were seen in 31 of 44 patients with accelerated-phase CML, CML with blast crisis, or Ph-positive ALL. In these two phases, the rates of major cytogenetic response were 45 percent and 25 percent, respectively. Responses were maintained in 95 percent of patients with chronic-phase disease and in 82 percent of patients with accelerated-phase disease, with a median follow-up more than 12 months and 5 months, respectively. Nearly all patients with lymphoid blast crisis and Ph-positive ALL had a relapse within six months. Responses occurred among all BCR-ABL genotypes, with the exception of the T315I mutation, which confers resistance to both dasatinib and imatinib in vitro. Myelosuppression was common but not dose-limiting.

CONCLUSIONS

Dasatinib induces hematologic and cytogenetic responses in patients with CML or Ph-positive ALL who cannot tolerate or are resistant to imatinib. (ClinicalTrials.gov number, NCT00064233 [ClinicalTrials.gov].).

Capsaicin-induced inactivation of sensory neurons promotes a more aggressive gene expression phenotype in breast cancer cells

Capsaicin-induced inactivation of sensory neurons has been reported to enhance metastasis of a murine breast cancer cell line, specifically enhancing myocardial metastases. Here we characterized changes in gene expression patterns in primary tumors which developed in capsaicin-treated vs. control mice. We identified a small cohort of genes (17) which all showed significant decreases in expression levels. All of the identified genes have been linked to cell growth, differentiation, and/or cancer progression. Three representative genes, Caspase-7 (an executor of apoptosis), ADAM-10 (A Disintegrin and Metalloprotease), and Elk-3 (a transcriptional repressor of the ternary factor subfamily of the Ets factors) were further investigated. All three showed dramatic downregulation at the protein level in primary tumors from capsaicin-treated animals compared with control (vehicle-treated) animals, and their expression was also lost in cell culture. Elk-3 and Caspase-7 were not expressed in vitro in cultured cell lines, suggesting that their expression was induced by the tumor microenvironment. Loss of Caspase-7 expression can be expected to result in loss of function of apoptotic pathways. At first glance, loss of ADAM-10 expression would be expected to result in decreased invasive capability, due to loss of matrix metalloprotease activity. However, just the opposite appears to be true. We found that ADAM-10 actually hydrolyzes Substance P. Specifically ADAM-10 produces the same growth-inhibitory products from Substance P (i.e., SP (1-7)) that Neprilysin does, so that loss of ADAM-10 expression actually results in loss of production of growth inhibitory peptides from Substance P. Similarly, ADAM-10 also efficiently hydrolyzes Calcitonin Gene-Related Peptide, which may act in concert with Substance P. Finally, overactivity of Ets transcriptional suppressor functions has been linked to inhibition of tumorigenesis (e.g., Erf and Mef), and in addition loss of Elk-3 expression might also be be linked to tumorigenesis via loss of its putative anti-inflammatory activities. There is anecdotal evidence in the literature to indicate that the rest of the down-regulated genes may also contribute to development of a more aggressive phenotype in this breast cancer model.

NUP98-LEDGF fusion and t(9;11) in transformed chronic myeloid leukemia

The molecular basis for disease progression in chronic myeloid leukaemia (CML) is poorly understood, but is believed to be a consequence of additional acquired genetic lesions. We describe here a case of CML who presented de novo in transformation with a t(9;11)(p21;p15) and NUP98-LEDGF fusion in addition to the t(9;22). The t(9;11) was present in only 2/45 (4%) of bone marrow metaphases, but 17/20 (85%) of metaphases from peripheral blood, suggesting an extramedullary or focal origin. This is the first description of NUP98-LEDGF in CML and strengthens the association between disease progression in and NUP98 abnormalities.

Loss of response to imatinib: mechanisms and management

The treatment of chronic myeloid leukemia (CML) has been revolutionized by the small molecule BCR-ABL-selective kinase inhibitor imatinib. Although imatinib is highly effective initially and generally well-tolerated, relapse is increasingly encountered clinically. Until recently, for the majority of CML patients with disease no longer responsive to imatinib, as well as for patients with imatinib intolerance, few effective therapeutic options existed. Our understanding of the major mechanisms of imatinib resistance has led to the clinical development of two novel BCR-ABL inhibitors that harbor significant therapeutic promise in early clinical trial experience. These agents, dasatinib (BMS-354825) and AMN107, are more potent inhibitors of BCR-ABL than imatinib, and moreover, harbor activity against nearly all imatinib-resistant BCR-ABL kinase domain mutant forms tested in vitro. Notably, neither of these compounds is effective against the imatinib-resistant BCR-ABL/T315I mutation. The potential availability of highly effective medications for the treatment of imatinib-resistant and intolerant cases of CML is expected to further complicate the timing of other effective therapies, such as allogeneic stem cell transplantation. Additionally, periodic genotyping of the BCR-ABL kinase domain to screen for drug-resistant mutations may play an increasingly important role in the future management of CML cases.