IκBα targeting promotes oxidative stress-dependent cell death

BACKGROUND

Oxidative stress is a hallmark of many cancers. The increment in reactive oxygen species (ROS), resulting from an increased mitochondrial respiration, is the major cause of oxidative stress. Cell fate is known to be intricately linked to the amount of ROS produced. The direct generation of ROS is also one of the mechanisms exploited by common anticancer therapies, such as chemotherapy.

METHODS

We assessed the role of NFKBIA with various approaches, including in silico analyses, RNA-silencing and xenotransplantation. Western blot analyses, immunohistochemistry and RT-qPCR were used to detect the expression of specific proteins and genes. Immunoprecipitation and pull-down experiments were used to evaluate protein-protein interactions.

RESULTS

Here, by using an in silico approach, following the identification of NFKBIA (the gene encoding IκBα) amplification in various cancers, we described an inverse correlation between IκBα, oxidative metabolism, and ROS production in lung cancer. Furthermore, we showed that novel IκBα targeting compounds combined with cisplatin treatment promote an increase in ROS beyond the tolerated threshold, thus causing death by oxytosis.

CONCLUSIONS

NFKBIA amplification and IκBα overexpression identify a unique cancer subtype associated with specific expression profile and metabolic signatures. Through p65-NFKB regulation, IκBα overexpression favors metabolic rewiring of cancer cells and distinct susceptibility to cisplatin. Lastly, we have developed a novel approach to disrupt IκBα/p65 interaction, restoring p65-mediated apoptotic responses to cisplatin due to mitochondria deregulation and ROS-production.

A Rare Case of Hodgkin Lymphoma of the Maxillary Sinus

Hodgkin lymphoma (HL) is an uncommon B-cell malignant disease. It usually presents with mediastinal and/or laterocervical lymph node localization, while primary extranodal HL is a rare entity giving rise to diagnostic and therapeutic challenges. It rarely presents as just extranodal localization, so its presence within the maxillary sinus without any lymphadenopathy is exceptional. Given the rarity of this localization, there is no standard treatment for maxillary sinus HL. We present a case of a patient with extranodal HL of the right maxillary sinus treated with primary surgery followed by adjuvant sequential chemoradiation therapy.

Association between High On-Aspirin Platelet Reactivity and Reduced Superoxide Dismutase Activity in Patients Affected by Type 2 Diabetes Mellitus or Primary Hypercholesterolemia

Platelet hyperactivation is involved in the established prothrombotic condition of metabolic diseases such as Type 2 Diabetes Mellitus (T2DM) and familial hypercholesterolemia (HC), justifying the therapy with aspirin, a suppressor of thromboxane synthesis through the irreversible inhibition of cyclooxygenase-1 (COX-1), to prevent cardiovascular diseases. However, some patients on aspirin show a higher than expected platelet reactivity due, at least in part, to a pro-oxidant milieu. The aim of this study was to investigate platelet reactivity in T2DM (n = 103) or HC (n = 61) patients (aspirin, 100 mg/day) and its correlation with biomarkers of redox function including the superoxide anion scavenger superoxide dismutase (SOD) and the in vivo marker of oxidative stress urinary 8-iso-prostaglandin F_2α. As results, in T2DM and HC subjects the prevalence of high on-aspirin platelet reactivity was comparable when both non-COX-1-dependent and COX-1-dependent assays were performed, and platelet reactivity is associated with a lower SOD activity that in a stepwise linear regression appears as the only predictor of platelet reactivity. To conclude, in T2DM and HC, similarly, the impairment of redox equilibrium associated with a decrease of SOD activity could contribute to a suboptimal response to aspirin.

<p>The Challenge of Hemorrhagic Shock Management During Low-Molecular-Weight Heparin Treatment</p>

The reversal of low-molecular-weight heparin (LMWH) and the management of bleeding patients on LMWH remain highly challenging. Even if LMWH is very extensively administered in the prophylaxis and treatment of venous thrombosis, specific antidotes are lacking, and reversal strategies have very weak grade of evidences on clinical effectiveness. We here describe a reversal strategy with protamine and FVIIa in a patient presenting with hemorrhagic shock and cardiocirculatory arrest.

Platelet function and activation markers in primary hypercholesterolemia treated with anti-PCSK9 monoclonal antibody: A 12-month follow-up

BACKGROUND AND AIMS

In the association between hypercholesterolemia (HC) and thrombotic risk platelet hyper-reactivity plays an important role. The inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) to reduce plasma LDL-cholesterol merges as effective therapeutic strategy to prevent cardiovascular (CV) events. Aim of this study was to verify whether a treatment up to 12 months with the monoclonal antibodies (mAbs) anti-PCSK9 influences platelet function in primary HC.

METHODS AND RESULTS

In patients affected by primary HC (n = 24), all on background of statin and 17 on acetyl salicylic acid (ASA), platelet function parameters were evaluated at baseline up to 12 months of treatment with the mAb anti-PCSK9 alirocumab or evolocumab. From baseline, the treatment with anti-PCSK9 mAbs: i) in ASA HC patients, significantly decreased platelet aggregation detected in platelet-rich plasma by light transmission aggregometry and in whole blood Platelet Function Analyzer-100 assay; ii) in all HC patients, significantly decreased platelet membrane expression of CD62P and plasma levels of the in vivo platelet activation markers soluble CD40 Ligand, Platelet Factor-4, and soluble P-Selectin. Furthermore, CD62P expression, and sP-Selectin, PF-4, sCD40L levels significantly correlated with serum PCSK9.

CONCLUSION

Besides markedly lowering LDL-c levels, our results suggest that HC patients benefit from anti-PCSK9 mAb treatment also for reducing platelet reactivity and increasing platelet sensitivity to the inhibitory effects of aspirin. These effects on platelets could play a role in the reduction of CV event incidence in patients treated with PCSK9 inhibitors.

Inhibition of bromodomain and extra-terminal proteins increases sensitivity to venetoclax in chronic lymphocytic leukaemia

The development of drugs able to target BTK, PI3k‐delta and BCL2 has dramatically improved chronic lymphocytic leukaemia (CLL) therapies. However, drug resistance to these therapies has already been reported due to non‐recurrent changes in oncogenic pathways and genes expression signatures. In this study, we investigated the cooperative role of the BCL2 inhibitor venetoclax and the BRD4 inhibitor JQ1. In particular, we found that JQ1 shows additional activity with venetoclax, in CLL cell lines and in ex vivo isolated primary CD19⁺ lymphocytes, arguing in favour of combination strategies. Lastly, JQ1 is also effective in venetoclax‐resistant CLL cell lines. Together, our findings indicated that the BET inhibitor JQ1 could be a promising therapy in CLL, both as first‐line therapy in combination with venetoclax and as second‐line therapy, after the emergence of venetoclax‐resistant clones.

Nuclear-cytoplasmic Shuttling in Chronic Myeloid Leukemia: Implications in Leukemia Maintenance and Therapy

Nuclear-cytoplasmic shuttling is a highly regulated and complex process, which involves both proteins and nucleic acids. Changes in cellular compartmentalization of various proteins, including oncogenes and tumor suppressors, affect cellular behavior, promoting or inhibiting proliferation, apoptosis and sensitivity to therapies. In this review, we will recapitulate the role of various shuttling components in Chronic Myeloid Leukemia and we will provide insights on the potential role of shuttling proteins as therapeutic targets.

Bone marrow granulomatosis: two case reports

Bone marrow granulomatosis is not a common finding and remains a diagnostic challenge. Here below we report two bizarre but not so rare cases of bone marrow granulomatosis: bone marrow involvement by Mycobacterium avium-intracellulare and reaction to intravesical administration of Bacillus Calmette-Guérin for non-muscle-invasive bladder cancer; two distinct culprits suggesting the wide range of possible causative factors of this histopathological pattern. In the discussion we provide a brief overview of causes and suggestions for a diagnostic approach.

Transferrin Saturation Inversely Correlates with Platelet Function

Background The association between iron overload (IO) and risk of cardiovascular disease is controversial. Epidemiological studies have found a significant negative association of transferrin (Tf) saturation and cardiovascular events suggesting that higher body iron possibly confer a protective effect towards developing cardiovascular events. The biological mechanisms of this phenomenon are unknown.

Objective This article investigates the role of IO on platelet reactivity.

Materials and Methods This study was a prospective case–control study comparing 45 patients with IO, mostly characterized by the HFE gene mutations C282Y and/or H63D, with 32 healthy controls. We evaluated: (1) platelet aggregation in both platelet-rich plasma and whole blood, (2) platelet membrane expression of the activation marker CD62P, (3) activation of platelet signalling phosphoinositide 3-kinase /Akt and mitogen-activated protein kinase/extracellular signal-regulated kinases (Erk)-1/2 pathways, (4) a pattern of in vivo platelet activation markers, and (5) iron biomarker predictors of platelet reactivity.

Results IO patients had significantly lower platelet aggregability, expression of CD62P and phosphorylation amounts of pAkt and pErk-2 in response to agonists. Furthermore, patients with higher Tf saturation levels were characterized by lower circulating levels of sCD40L, PDGF-BB and thromboxane B2. Platelet aggregation and activation parameters inversely correlated with Tf saturation and the stepwise multivariate regression analysis underlined the role of Tf saturation in predicting platelet reactivity. We also found that in vitro platelet exposure to diferric Tf, but not to iron-depleted TF, dose-dependently inhibited platelet function in all investigated subjects.

Conclusion Tf saturation is inversely associated with platelet reactivity and this could explain, at least in part, the association of high Tf and lower risk of cardiovascular diseases in IO.

Therapeutic inhibition of USP7-PTEN network in chronic lymphocytic leukemia: a strategy to overcome TP53 mutated/deleted clones

Chronic Lymphocytic Leukemia (CLL) is a lymphoproliferative disorder with either indolent or aggressive clinical course. Current treatment regiments have significantly improved the overall outcomes even if higher risk subgroups - those harboring TP53 mutations or deletions of the short arm of chromosome 17 (del17p) - remain highly challenging. In the present work, we identified USP7, a known de-ubiquitinase with multiple roles in cellular homeostasis, as a potential therapeutic target in CLL. We demonstrated that in primary CLL samples and in CLL cell lines USP7 is: i) over-expressed through a mechanism involving miR-338-3p and miR-181b deregulation; ii) functionally activated by Casein Kinase 2 (CK2), an upstream interactor known to be deregulated in CLL; iii) effectively targeted by the USP7 inhibitor P5091. Treatment of primary CLL samples and cell lines with P5091 induces cell growth arrest and apoptosis, through the restoration of PTEN nuclear pool, both in TP53-wild type and -null environment. Importantly, PTEN acts as the main tumor suppressive mediator along the USP7-PTEN axis in a p53 dispensable manner. In conclusion, we propose USP7 as a new druggable target in CLL.

The BCR-ABL/NF-κB signal transduction network: a long lasting relationship in Philadelphia positive Leukemias

The Nuclear Factor-kappa B (NF-κB) family of transcription factors plays a key role in cancer pathogenesis due to the ability to promote cellular proliferation and survival, to induce resistance to chemotherapy and to mediate invasion and metastasis. NF-κB is recruited through different mechanisms involving either canonical (RelA/p50) or non-canonical pathways (RelB/p50 or RelB/p52), which transduce the signals originated from growth-factors, cytokines, oncogenic stress and DNA damage, bacterial and viral products or other stimuli. The pharmacological inhibition of the NF-κB pathway has clearly been associated with significant clinical activity in different cancers. Almost 20 years ago, NF-κB was described as an essential modulator of BCR-ABL signaling in Chronic Myeloid Leukemia and Philadelphia-positive Acute Lymphoblastic Leukemia. This review summarizes the role of NF-κB in BCR-ABL-mediated leukemogenesis and provides new insights on the long lasting BCR-ABL/NF-κB connection.

Unleashing the Guardian: The Targetable BCR-ABL/HAUSP/PML/PTEN Network in Chronic Myeloid Leukemia

The complete eradication of Chronic Myeloid Leukemia is still challenging even in the era of highly selective and potent BCR-ABL tyrosine kinase inhibitors (TKIs). The 'Achilles heel' of TKI-based CML therapy is the inability of TKI to effectively target CML stem cells. Several pathways have been described to induce TKI insensitiveness in quiescent CML stem cells. In this review, we will describe the BCR-ABL/HAUSP/PML/PTEN network, whose signaling mediators converge to regulate the function of the tumor suppressor PTEN. We will also highlight the pharmacological strategies to modulate PTEN functions in order to sustain CML stem cell eradication.

Detection and management of retroperitoneal cystic lesions: A case report and review of the literature

The identification of cystic lesions within the retroperitoneal space is a rare event that poses clinicians the challenge of a difficult diagnosis and disease management. Retroperitoneal cystic lesions account for a group of lesions that range from common benign lesions (e.g., lymphoceles developing as a surgical complication) to rare aggressive malignant neoplasms. Currently, in the majority of cases, image-guided procedures allow for a pathological diagnosis to be achieved in these challenging lesions, thus offering the chance of an appropriate treatment; however, the overall clinical assessment of retroperitoneal cysts is highly demanding. The present study reports the management of a representative clinical case, presenting with a voluminous cystic mass able to dislocate cave vein, whose diagnosis was preceded by a deep vein thrombosis. Computed tomography-scan and ultrasound guided percutaneous drainage were performed to achieve the diagnosis. Following the discussion of the current case report, a review of the pathological and radiological characteristics of retroperitoneal cystic lesions is presented.

Glucagon-like peptide 1-related peptides increase nitric oxide effects to reduce platelet activation

Glucagon-like peptide 1 (GLP-1) is object of intensive investigation for not only its metabolic effects but also the protective vascular actions. Since platelets exert a primary role in the pathogenesis of atherosclerosis, inflammation and vascular complications, we investigated whether GLP-1 directly influences platelet reactivity. For this purpose, in platelets from 72 healthy volunteers we evaluated GLP-1 receptor (GLP-1R) expression and the effects of a 15-minute incubation with the native form GLP-1(7–36), the N-terminally truncated form GLP-1(9–36) and the GLP-1 analogue Liraglutide (100 nmol/l) on: i) aggregation induced by collagen or arachidonic acid (AA); ii) platelet function under shear stress; iii) cGMP and cAMP synthesis and cGMP-dependent protein kinase (PKG)-induced Vasodilator-Stimulated-Phosphoprotein (VASP) phosphorylation; iv) activation of the signalling molecules Phosphatidylinositol 3-Kinase (PI3-K)/Akt and Mitogen Activated Protein Kinase (MAPK)/ERK-1/2; and v) oxidative stress. Experiments were repeated in the presence of the nitric oxide donor Na–nitroprusside. We found that platelets constitutively express GLP-1R and that, independently of GLP-1R, GLP-1(7–36), GLP-1(9–36) and Liraglutide exert platelet inhibitory effects as shown by: a) increased NO-antiaggregating effects, b) increased the activation of the cGMP/PKG/VASP pathway, c) reduced the activation of PI3-K/Akt and MAPK/ERK-2 pathways, d) reduced the AA-induced oxidative stress. When the experiments were repeated in the presence of the antagonist of GLP-1R Exendin(9–39), the platelet inhibitory effects were maintained, thus indicating a mechanism independent of GLP-1R. In conclusion, GLP-1(7–36), its degradation product GLP-1(9–36) and Liraglutide exert similar inhibitory effects on platelet activation, suggesting a potential protective effect on the cardiovascular system.

IκB-α: At the crossroad between oncogenic and tumor-suppressive signals

Nuclear factor κB (NF-κB) is an essential component of tumorigenesis and resistance to cancer treatments. NFKB inhibitor α (IκB-α) acts as a negative regulator of the classical NF-κB pathway through its ability to maintain the presence of NF-κB in the cytoplasm. However, IκB-α is also able to form a complex with tumor protein p53, promoting its inactivation. Recently, we demonstrated that IκB-α is able to mediate p53 nuclear exclusion and inactivation in chronic myeloid leukemia, indicating that IκB-α can modulate either oncogenic or tumor-suppressive functions, with important implications for cancer treatment. The present review describes the role of IκB-α in cancer pathogenesis, with particular attention to hematological cancers, and highlights the involvement of IκB-α in the regulation of p53 tumor-suppressive functions.

Mechanisms of p53 Functional De-Regulation: Role of the IκB-α/p53 Complex

TP53 is one of the most frequently-mutated and deleted tumor suppressors in cancer, with a dramatic correlation with dismal prognoses. In addition to genetic inactivation, the p53 protein can be functionally inactivated in cancer, through post-transductional modifications, changes in cellular compartmentalization, and interactions with other proteins. Here, we review the mechanisms of p53 functional inactivation, with a particular emphasis on the interaction between p53 and IκB-α, the NFKBIA gene product.

The targetable role of herpes virus-associated ubiquitin-specific protease (HAUSP) in p190 BCR-ABL leukemia

Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL) is driven by the p190 breakpoint cluster region (BCR)-ABL isoform. Although effectively targeted by BCR-ABL tyrosine kinase inhibitors (TKIs), ALL is associated with a less effective response to TKIs compared with chronic myeloid leukemia. Therefore, the identification of additional genes required for ALL maintenance may provide possible therapeutic targets to aid the eradication of this cancer. The present study demonstrated that p190 BCR-ABL is able to interact with the deubiquitinase herpesvirus-associated ubiquitin-specific protease (HAUSP), which in turn affects p53 protein stability. Notably, the inhibition of HAUSP with small molecule inhibitors promoted the upregulation of p53 protein levels. These results suggest that HAUSP inhibitors may harbor clinically relevant implications in the treatment of Ph⁺ ALL.

Non genomic loss of function of tumor suppressors in CML: BCR-ABL promotes IκBα mediated p53 nuclear exclusion

Tumor suppressor function can be modulated by subtle variation of expression levels, proper cellular compartmentalization and post-translational modifications, such as phosphorylation, acetylation and sumoylation. The non-genomic loss of function of tumor suppressors offers a challenging therapeutic opportunity. The reactivation of a tumor suppressor could indeed promote selective apoptosis of cancer cells without affecting normal cells. The identification of mechanisms that affect tumor suppressor functions is therefore essential. In this work, we show that BCR-ABL promotes the accumulation of the NFKBIA gene product, IκBα, in the cytosol through physical interaction and stabilization of the protein. Furthermore, BCR-ABL/IκBα complex acts as a scaffold protein favoring p53 nuclear exclusion. We therefore identify a novel BCR-ABL/IκBα/p53 network, whereby BCR-ABL functionally inactivates a key tumor suppressor.

The non-genomic loss of function of tumor suppressors: an essential role in the pathogenesis of chronic myeloid leukemia chronic phase

BACKGROUND

Chronic Myeloid Leukemia was always referred as a unique cancer due to the apparent independence from tumor suppressors' deletions/mutations in the early stages of the disease. However, it is now well documented that even genetically wild-type tumor suppressors can be involved in tumorigenesis, when functionally inactivated. In particular, tumor suppressors' functions can be impaired by subtle variations of protein levels, changes in cellular compartmentalization and post-transcriptional/post-translational modifications, such as phosphorylation, acetylation, ubiquitination and sumoylation. Notably, tumor suppressors inactivation offers challenging therapeutic opportunities. The reactivation of an inactive and genetically wild-type tumor suppressor could indeed promote selective apoptosis of cancer cells without affecting normal cells.

MAIN BODY

Chronic Myeloid Leukemia (CML) could be considered as the paradigm for non-genomic loss of function of tumor suppressors due to the ability of BCR-ABL to directly promote functionally inactivation of several tumor suppressors.

SHORT CONCLUSION

In this review we will describe new insights on the role of FoxO, PP2A, p27, BLK, PTEN and other tumor suppressors in CML pathogenesis. Finally, we will describe strategies to promote tumor suppressors reactivation in CML.

Rare Bone Marrow Biopsy Complication: A Challenging Case of Sacroiliitis and Staphilococcus Aureus Sepsis

Bone marrow biopsy is a mandatory procedure to diagnose several hematological disorders. This invasive analysis is generally safe and the procedure-related risks are rare and include bleeding at the site of puncture and, very occasionally, local infections. Here, we describe a case of sacroiliitis that occurred as a consequence of bone marrow biopsy.

BCR-ABL inactivates cytosolic PTEN through Casein Kinase II mediated tail phosphorylation

The tumor suppressive function of PTEN is exerted within 2 different cellular compartments. In the cytosol-membrane, it negatively regulates PI3K-AKT pathway through the de-phosphorylation of phosphatidylinositol (3,4,5)-triphosphate (PIP3), therefore blocking one of the major signaling transduction pathways in tumorigenesis. In the nucleus, PTEN controls genomic stability and cellular proliferation through phosphatase independent mechanisms. Importantly, impairments in PTEN cellular compartmentalization, changes in protein levels and post-transductional modifications affect PTEN tumor suppressive functions. Targeting mechanisms that inactivate PTEN promotes apoptosis induction of cancer cells, without affecting normal cells, with appealing therapeutic implications. Recently, we have shown that BCR-ABL promotes PTEN nuclear exclusion by favoring HAUSP mediated PTEN de-ubiquitination in Chronic Myeloid Leukemia. Here, we show that nuclear exclusion of PTEN is associated with PTEN inactivation in the cytoplasm of CML cells. In particular, BCR-ABL promotes Casein Kinase II-mediated PTEN tail phosphorylation with consequent inhibition of the phosphatase activity toward PIP3. Targeting Casein Kinase II promotes PTEN reactivation with apoptosis induction. We therefore propose a novel BCR-ABL/CKII/PTEN pathway as a potential target to achieve synthetic lethality with tyrosine kinase inhibitors.

The Role of PTEN in Myeloid Malignancies

PTEN deletion in the mouse and in the zebrafish highlights the essential role of this tumor suppressor in the development of myeloid malignancies, in particular acute myeloid leukemia and myeloproliferative disorders. In humans, extensive genetic sequences of myeloid malignancies did not reveal recurrent PTEN mutations and deletions. However, PTEN was shown to be functionally inactivated in several acute myeloid leukemia and chronic myeloid leukemia samples, through both post-trasductional modifications, changes in protein levels and cellular compartmentalization. Notably, non genomic inactivation of PTEN in myeloid malignancies could represent a challenging therapeutic opportunity for these diseases. Targeting those mechanisms that affect PTEN function could indeed promote PTEN reactivation with consequent cancer selective apoptosis induction. In this review we will describe the role of PTEN in the development of myeloid malignancies.

When collateral vessels matter: asymptomatic Leriche syndrome

While acute arterial occlusion causes life-threatening ischemia and organ damage requiring urgent revascularization, the incidental identification of arterial occlusions in asymptomatic patients represents a therapeutic dilemma in clinicians. Does chronic asymptomatic artery occlusion require specific treatment?

Small bowel cancer diagnosis: role of nuclear magnetic resonance

The diagnosis of small intestine tumors is challenging. Even in the era of modern medicine, standard approaches including echography, computed tomography-scan and conventional endoscopy are unable to reveal small bowel lesions. Video-capsule has substantially improved the evaluation of small bowel; however this procedure cannot be proposed to all patients and in particular to those experiencing intestine sub-occlusion. Nuclear magnetic resonance (NRM) of the abdomen is an additional diagnostic approach that offers high sensitivity in the identification of small bowel lesions. Here, we describe a case of small bowel neoplasia indentified with NRM of the abdomen.

The challenging diagnosis of pancreatic masses: not all tumors are cancers

In the elderly patients, where biopsy-induced complications could outweigh the benefit, the identification of pancreatic masses is generally referred to as a synonymous of pancreatic cancer and patients are dismissed with no further options than palliative and supportive care. Notwithstanding, not all pancreatic tumors are cancers and therefore alternative diagnoses need to be investigated, especially when patients are unfit for invasive diagnostic procedures. Here, we report a case of an aged patient that was admitted to an internal medicine division for a previously diagnosed pancreatic cancer. The reassessment of the diagnosis has allowed identifying the pancreatic mass as a manifestation of focal pancreatitis in the context of an IgG4-related disease. Accordingly, patient was treated with steroids with rapid clinical improvement. This clinical case suggests that autoimmune diseases should always be considered in the differential diagnosis of pancreatic masses of the elderly.

BCR-ABL promotes PTEN downregulation in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the t(9;22) translocation coding for the chimeric protein p210 BCR-ABL. The tumor suppressor PTEN plays a critical role in the pathogenesis of CML chronic phase, through non genomic loss of function mechanisms, such as protein down-regulation and impaired nuclear/cytoplasmic shuttling. Here we demonstrate that BCR-ABL promotes PTEN downregulation through a MEK dependent pathway. Furthermore, we describe a novel not recurrent N212D-PTEN point mutation found in the EM2 blast crisis cell line.

HAUSP compartmentalization in chronic myeloid leukemia

INTRODUCTION

PTEN plays an essential role in the pathogenesis of chronic myeloid leukemia. Recently, we have shown that BCR-ABL promotes PTEN nuclear exclusion, through the modulation of HAUSP activity.

OBJECTIVES

Here, we investigate HAUSP cellular compartmentalization in primary CML samples.

RESULTS

While in normal CD34 positive cells HAUSP is expressed mostly in the nucleus, in CML CD34 cells HAUSP is expressed both in the nuclear bodies and in the cytoplasm.

CONCLUSIONS

This observation suggests that HAUSP behaves as a shuttling protein in CML. It can bind to BCR-ABL in the cytosol, where it is phosphorylated on tyrosine residues, and it maintains the proper compartmentalization in the nuclear bodies, where it acts as part of a PML network to regulate PTEN de-ubiquitination.

Valproate enhances imatinib-induced growth arrest and apoptosis in chronic myeloid leukemia cells

BACKGROUND

The objective of this study was to evaluate the ability of the clinically available histone deacetylase (HDAC) inhibitor valproate to enhance the cytotoxicity of the Bcr-Abl inhibitor imatinib in imatinib-resistant cell lines.

METHODS

Interactions between imatinib, and valproate have been examined in imatinib-sensitive and -resistant chronic myeloid leukemia (CML)cell lines (K562, KCL-22, CML-T1) and in bone marrow mononuclear cells (MNCs) derived from imatinib-resistant CML patients.

RESULTS

In imatinib-sensitive cell lines, cotreatment with imatinib 0.5 muM and valproate 5 microM for 48 hours potently enhanced imatinib-induced growth arrest and apoptosis. In resistant cell lines and in primary MNCs derived from imatinib-rsistant patients, valproate restored sensitivity to the cytotoxic effects of imatinib. Coexposure of cells to valproate and imatinib was associated with repression of several genes involved in Bcr-Abl transformation. In particular, the combination valproate-imatinib downregulated the expression of Bcr-Abl and the antiapoptotic protein Bcl-2, which is particularly overexpressed in imatinib-resistant clones.

CONCLUSIONS

Data from this study suggested that administration of the clinically available HDAC inhibitor valproate may be a powerful strategy to enhance cytotoxic effects of imatinib in those patient resistant to imatinib or in which complete cytogenetic remission has been not reached.

Increase in platelet count in older, poor-risk patients with acute myeloid leukemia or myelodysplastic syndrome treated with valproic acid and all-trans retinoic acid

BACKGROUND

The authors investigated the efficacy and safety of the histone deacetylase inhibitors valproic acid (VPA) and all-trans retinoic acid (ATRA) as differentiation agents in a cohort of older, poor-risk patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS).

METHODS

Twenty older patients with recurrent or refractory AML or MDS were treated in a Phase II protocol with sequential VPA and ATRA therapy. VPA was started at a dose of 10 mg/kg per day and then escalated to achieve the serum concentration of 45-100 microg/mL. ATRA was added at 45 mg/square meters (sm) per day when VPA reached the target serum concentration. Only patients treated continuously for > or = 2 months were considered evaluable.

RESULTS

Hematologic improvement, according to World Health Organization criteria, was observed in 6 of 20 patients enrolled in the protocol but in 6 of 11 considered evaluable. In five patients, a major platelet response was observed, achieving platelet transfusion independence. Three of these five patients also exhibited a minor erythroid response. A sixth patient showed both a minor erythroid response and a platelet response. The median duration of response was 189 days (range, 63-550 days). No significant reduction in the blast count was observed. Grade 3 neurocortical toxicity was observed in four patients. Severe bone pain was experienced by 4 patients (2 Grade 4 and 2 Grade 3) and was associated with an increase in the peripheral blast cell count. Treatment with ATRA did not modify the response observed with VPA alone.

CONCLUSIONS

Differentiation therapy with VPA was of clinical benefit in approximately 30% of elderly patients with AML and MDS of the refractory anemia with excess of blast type with unfavorable prognostic features. A striking platelet transfusion independence lasting several months may be obtained in some patients, reducing the burden of palliative care and improving the quality of life.

Autologous HSCT for severe progressive multiple sclerosis in a multicenter trial: impact on disease activity and quality of life

Hematopoietic stem cell transplantation (HSCT) has been proposed for the treatment of severe multiple sclerosis (MS). In a phase 2 multicenter study we selected 19 non-primary progressive MS patients showing high disease activity on the basis of both brain magnetic resonance imaging (MRI) and sustained clinical deterioration despite conventional treatments. After stem cell mobilization with cyclophosphamide (CY) and filgrastim, patients were conditioned with BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea), cytosine arabinoside, etoposide, and melphalan (BEAM) followed by antithymocyte globulin (ATG). Unmanipulated peripheral blood stem cells (PBSCs) were then infused. No maintenance treatment was administered with a median follow-up of 36 months (range, 12 to 72 months). All patients showed clinical stabilization or improvement; 3 subsequently deteriorated, 1 beyond the baseline. No MRI active lesions were detected after the HSCT except in 1 patient who showed a new lesion at 4.5 years. Infections were limited and restricted to 3 months after HSCT. Health-related quality of life was assessed through the 54-item MS quality of life (MSQOL-54) questionnaire, showing a statistically significant improvement in both composite scores and in most of the individual domains. HSCT is able to induce a prolonged clinical stabilization in severe progressive MS patients, resulting in both sustained treatment-free periods and quality of life improvement.

Quantitative assessment of WT1 expression by real time quantitative PCR may be a useful tool for monitoring minimal residual disease in acute leukemia patients

In order to verify if quantitative assessment of the WT1 transcript amount by the real time quantitative PCR (RQ-PCR) can be used as a marker for minimal residual disease detection, the WT1 transcript amount was determined in BM and PB samples of patients with myeloid and lymphoid acute leukemia, in normal controls, in regenerating bone marrow samples and in purified CD34-positive cells from normal subjects. In 10 patients bearing a fusion gene transcript suitable for minimal residual disease quantitative assessment, we performed a simultaneous analysis of the WT1 and of the fusion-gene transcript at sequential time intervals during follow-up. Sequential WT1 analysis was also performed in five AML patients lacking additional molecular markers. The data obtained show that normal and regenerating BM samples and purified CD34-positive cells consistently express minimal amounts of WT1 transcript and that this is extremely low and frequently undetectable in normal PB. By contrast, high levels of WT1 expression are present in the BM and PB samples of all acute leukemia (AL) cases at diagnosis. The WT1 levels during follow-up were found to follow the pattern of the other molecular markers (fusion gene transcripts) used for MRD monitoring and increased WT1expression in the BM and/or PB during follow-up of AL patients was always found to be predictive of an impending hematological relapse.

Assessment of minimal residual disease (MRD) in CBFbeta/MYH11-positive acute myeloid leukemias by qualitative and quantitative RT-PCR amplification of fusion transcripts

The inv(16)(p13q22) chromosomal rearrangement associated with FAB M4Eo acute myeloid leukemia (AML) subtype is characterized by the presence of the CBFbeta/MYH11 fusion transcript that can be used to detect minimal residual disease (MRD). However, qualitative RT-PCR studies of MRD have so far produced conflicting results and seem of limited prognostic value. We have evaluated retrospectively MRD in a large series of CBFbeta/MYH11-positive patients employing both qualitative and quantitative (real-time PCR) approaches. 186 bone marrow samples from 36 patients were examined with a median follow-up of 27.5 months; 15 patients relapsed during follow-up. In qualitative studies, carried out by 'nested' RT-PCR assay, all patients in complete remission (CR) immediately after induction/consolidation therapy were found to be PCR positive. However, follow-up samples at later time points were persistently negative (except one case) in patients remaining in continuous CR (CCR) for more than 12 months. 16 patients were evaluated by quantitative real-time PCR assay: CBFbeta/MYH11 transcript copy number was normalized for expression of the housekeeping gene ABL, expressed as fusion gene copy number per 10(4) copies of ABL. A 2-3 log decline in leukemic transcript copy number was observed after induction/consolidation therapy. After achieving CR, the mean copy number was significantly higher in patients destined to relapse compared to patients remaining in CCR (151 vs 9, P < 0.0001 by Mann-Whitney test). Moreover, in CCR patients, the copy number dropped below the detection threshold after the treatment protocol was completed and remained undetectable in subsequent MRD analysis in accordance with results obtained by qualitative RT-PCR. On the contrary, in the seven patients who relapsed, the copy number in CR never declined below the detection threshold; thus a cut-off value discriminating these two groups of patients could be established. The findings of our study, if confirmed, might confer an important predictive value to quantitative real-time PCR determinations of MRD in patients with inv(16) leukemia.

BCR/ABL transcripts and leukemia phenotype: an unsolved puzzle

The Philadelphia chromosome, arising as a consequence of the t(9;22) translocation, is one of the most frequent and certainly the most known cytogenetic abnormality present in human hematological malignancies. Unlike the vast majority of the other translocations, its presence is not restricted to a specific leukemia phenotype, but is found associated with chronic myelogenous leukemia as well as with a large percentage of acute lymphoblastic leukemias, particularly in elderly patients. Although its molecular counterpart is always represented by a rearrangement between the BCR and the ABL genes, this shows a certain degree of molecular variability. The pathogenetic relationship with the different leukemia phenotypes which have been found to be associated still awaits to be fully elucidated. However, a number of old and more recent observations seem to suggest that not only qualitative differences in the type of BCR/ABL proteins expressed, but also quantitative variations in their total level within the cells may have an important role in determining the leukemia phenotype.

The common TEL/AML1 rearrangement does not represent a frequent event in acute lymphoblastic leukaemia occuring in children with Down syndrome

Individuals with constitutional trisomy 21 (Down syndrome) are at increased risk of developing acute leukaemias, both of myeloid and lymphoid lineage. Although the cause of leukaemia in Down syndrome (DS) remains unknown, potential candidate genes include the ones on chromosome 21, and in particular AML1, the rearrangement of which in the t(8,21) is associated with the French-American-British (FAB) classification M2 subtype of acute myeloid leukaemia (AML) in the general population and has been described in Down patients with AML-M2. Recently, a new rearrangement involving AML1, the t(12;21), producing the TEL/AML1 hybrid transcript, has been described by molecular analysis as the most recurrent genetic lesion in childhood acute lymphoblastic leukemia (ALL). In order to investigate whether the t(12;21) could give a molecular clue as to the precise basis of the etiologic association between DS and acute lymphoblastic leukemia, we tested a series of 11 consecutive cases of ALL in DS children for the presence of the TEL/AML1 transcript, by RT-PCR analysis. We report absence of the TEL/AML1 rearrangement among the 11 cases tested. This data may be suggestive of alternative pathways involved in the pathogenesis of ALL in children with constitutional trisomy 21.

Molecular events in chronic myeloid leukemia progression

Chronic myelogenous leukemia presents two distinct clinical phases: the chronic phase is characterised by a marked expansion of the myeloid compartment which still retains a normal differentiative capacity, whereas a differentiation block is the clinical hallmark of the acute transformation. The molecular mechanism underlying the CML progression are still poorly understood. The occurrence of additional molecular lesions, involving the p53, the RAS and the p16 genes may complement and fulfil the BCR/ABL transforming potential, finally leading to an acute leukemic phenotype. However, several lines of evidence suggest that also quantitative changes of the BCR/ABL transcript amounts could explain the progression of the leukemic phenotype in the BCR/ABL-positive hematologic malignancies.

Consistent amounts of acute leukemia-associated P190BCR/ABL transcripts are expressed by chronic myelogenous leukemia patients at diagnosis

In chronic myelogenous leukemia (CML), the Philadelphia (Ph) chromosome translocation results in the formation of BCR/ABL genes, normally transcribed in two types of hybrid transcripts with a b2a2 or b3a2 BCR/ABL junction, which give origin to 210-kD fusion proteins (P210). A third type of BCR/ABL (with e1a2 type of junction) has been identified in approximately 50% of the Ph-positive acute lymphoblastic leukemia (Ph+ALL) cases and results in the production of a BCR/ABL protein of 190 kD (P190). The presence of this transcript has been associated almost exclusively with the presence of an acute leukemia phenotype. By contrast, here we describe that in addition to transcripts with the b2a2 and b3a2 types of junction corresponding to the P210 proteins, virtually all CMLs at diagnosis bear also BCR/ABL transcripts showing the e1a2 type of junction, which correspond to the acute leukemia-associated P190 protein. With a quantitative polymerase chain reaction assay we found that the amount of the e1a2 mRNA present in CMLs in chronic phase, although in absolute amount much lower than that present in Ph+ ALLs, represents in most cases approximately 20% to 30% of the total BCR/ABL transcripts. Moreover, using a novel and very sensitive Western blot technique, we detected relevant amounts of P190 protein in addition to P210 from peripheral cells of two of the patients.

Genetic analysis of chromosome 13 deletions in BCR/ABL negative chronic myeloproliferative disorders

Chromosomal deletions of band 13q14 occur recurrently in BCR/ABL negative chronic myeloproliferative disorders (CMPD), including myelosclerosis with myeloid metaplasia (MMM), polycythemia vera (PV), essential thrombocythemia (ET), juvenile chronic myeloid leukemia (JCML), and the so-called BCR/ABL- chronic myeloid leukemia (CML). The RBI tumor suppressor locus, mapping to 13q14, has long since been hypothesized as the important gene. In this report, we have determined the frequency of 13q14 deletions at the molecular level in a large panel of BCR/ABL- CMPD at different disease stages and performed a detailed genetic analysis of gross rearrangements/deletions and point mutations of the RBI gene in these disorders. Our data show that molecular deletions of 13q14 are detected in a relatively large fraction of BCR/ABL- CMPD (38%), that they appear to be more frequent in MMM than in other BCR/ABL- CMPD, and that they may be present at diagnosis or occur during blastic evolution of the neoplasia. The RBI gene displayed a germline configuration in all BCR/ABL- CMPD tested, suggesting that 13q14 deletions in these disorders affect a tumor suppressor locus distinct from RBI.

Polyclonal haemopoieses associated with long-term persistence of the AML1-ETO transcript in patients with FAB M2 acute myeloid leukaemia in continous clinical remission

The t(8;21) (q22;q22) translocation is a recurring chromosomal abnormality observed in about 20-40% of AML patients with subtype FAB M2 (AML-M2). The molecular facet of this translocation is represented by the formation of a new hybrid gene, the AML1-ETO, which is regularly transcribed in a chimaeric mRNA and translated into a new fusion protein believed to have a key role in the pathogenesis of this type of leukaemia. We looked for the presence of AML1-ETO transcripts, by RT-PCR, in 49 unselected patients affected by AML-M2 diagnosed at various Italian Institutions. A hybrid transcript was detected in 11 cases (23%). Minimal residual disease status was investigated in three patients in continuous complete remission (CCR) after a median follow-up of 44 months; at least one sample from each subject was found positive for the AML1-ETO transcript suggesting a long-term persistence of t(8;21) leukaemic cells. In two female patients in CCR a 'clonality' analysis was performed on peripheral blood DNA by exploiting the X chromosome inactivation pattern of the human androgen-receptor gene (HUMARA); in both cases the results were consistent with the presence of a polyclonal haemopoiesis. Our data confirm that the persistence of residual cells expressing the AML1-ETO transcripts is a frequent occurrence even in patients with long-term remission; on the other hand, clonality assays indicate that in t(8;21) leukaemias long-term remission haemopoiesis is sustained by a polyclonal bone marrow reconstitution.