Src kinase-induced phosphorylation of annexin A2 mediates glucocorticoid resistance in MLL-rearranged infant acute lymphoblastic leukemia

MLL-rearranged infant acute lymphoblastic leukemia (ALL) (<1 year of age) are frequently resistant to glucocorticoids, like prednisone and dexamethasone. As poor glucocorticoid responses are strongly associated with therapy failure, overcoming glucocorticoid resistance may be a crucial step towards improving prognosis. Unfortunately, the mechanisms underlying glucocorticoid resistance in MLL-rearranged ALL largely remain obscure. We here defined a gene signature that accurately discriminates between prednisolone-resistant and prednisolone-sensitive MLL-rearranged infant ALL patient samples, demonstrating that, among other genes, high-level ANXA2 is associated with prednisolone resistance in this type of leukemia. Further investigation demonstrated that the underlying factor of this association was the presence of Src kinase-induced phosphorylation (activation) of annexin A2, a process requiring the adapter protein p11 (encoded by human S100A10). shRNA-mediated knockdown of either ANXA2, FYN, LCK or S100A10, all led to inhibition of annexin A2 phosphorylation and resulted in marked sensitization to prednisolone. Likewise, exposure of prednisolone-resistant MLL-rearranged ALL cells to different Src kinase inhibitors exerting high specificity towards FYN and/or LCK had similar effects. In conclusion, we here present a novel mechanism of prednisolone resistance in MLL-rearranged leukemias, and propose that inhibition of annexin A2 phosphorylation embodies a therapeutic strategy for overcoming resistance to glucocorticoids in this highly aggressive type of leukemia.

Assessment of the short-term functional outcome after urethroplasty: a prospective analysis

OBJECTIVES

To assess the short-term functional outcomes on urinary symptoms, erectile function, urinary continence and patient's satisfaction after urethroplasty.

MATERIALS AND METHODS

A prospective analysis was done in 21 patients who underwent urethroplasty. An assessment of the urinary flow, urinary symptoms (International Prostate Symptoms Score <IPSS>), erectile function (International Index of Erectile Function-5 <IIEF-5>) and urinary continence International Consultation Committee on Incontinence Questionnaire male Short Form <ICI-Q-SF>) was done before urethroplasty and 6 weeks and 6 months after urethroplasty. Patients were also asked to score their satisfaction with the urethroplasty after 6 weeks and 6 months.

RESULTS

Mean patient's age was 48 years range: 26-80 years). Mean stricture length was 4.2 cm (range: 1-12 cm). Three patients suffered a stricture recurrence. Mean maximum urinary flow increased from 5.83 mL/s to 24.92 mL/s (p < 0.001). Mean IPSS preoperative, 6 weeks and 6 months postoperative was respectively 15.86, 4.60 and 6.41(p < 0.001). The mean IIEF-5 score preoperative, 6 weeks and 6 months postoperative was respectively 15, 12.13 and 11.62 (not significant). The mean ICI-Q-SF score preoperative, 6 weeks and 6 months postoperative was respectively 10.47, 8.33 (p = 0.04) and 9.47 (p = 0.31). Patient's satisfaction 6 weeks and 6 months postoperative was respectively 17.14/20 and 17.12/20.

CONCLUSIONS

Urethroplasty leads to a significant improvement in urinary flow and IPSS and urinary continence is tending to improve. Although not significant, erectile function was slightly diminished after urethroplasty. Functional outcome should be assessed when urethroplasty is performed.

The Use of In Vitro Systems for Evaluating Immunotoxicity: The Report and Recommendations of an ECVAM Workshop

This is the report of a workshop organised by the European Centre for the Validation of Alternative Methods (ECVAM). ECVAM's main goal, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods that are of importance to the biosciences and which replace, reduce or refine the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures that would enable it to become well informed about the state-of-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organization of ECVAM workshops on specific topics, at which small groups of invited experts would review the current status of various types of in vitro tests and their potential uses, and make recommendations about the best ways forward (Anonymous, 1994). The workshop on "The use of in vitro systems for evaluating Immunotoxicity" was held at ECVAM (Ispra), Italy, on 24th-26th November 2003. The participants represented academia, national organizations, international regulatory bodies and industry. The aim of the workshop was to review the state-of-the-art in the field of in vitro immunotoxicology, and to develop strategies towards the replacement of in vivo testing. At the end of this report are listed the recommendations that should be considered for prevalidation and validation of relevant and reliable procedures, that could replace the use of animals in chemical and cosmetics toxicity testing.

Household chemicals, immune function, and allergy: a commentary

In recent decades, in the US and in Western and Northern Europe, there has been a significant increase in the prevalence of atopic allergic disease. Although that increase may now be slowing, or have already reached a plateau, there remains considerable interest in the factor or factors that may have caused this increased susceptibility to allergy and asthma. Certainly, the changes recorded have been too rapid to implicate a change in the gene pool, and for that reason attention has focused on the possible impact of environmental, dietary, and lifestyle factors. Although the hygiene hypothesis proposes that increased susceptibility to allergic sensitization is associated with changes in childhood exposure pathogenic microorganisms, other factors have been considered also. Among these is exposure to chemicals and atmospheric pollutants. There is some evidence that exposure to certain chemicals may elicit or exacerbate respiratory reactions in those who are already sensitized, or who already have existing airway disease. However, a recent article has proposed that exposure to specific household cleaning products may be one factor that is able to affect susceptibility to allergic sensitization. In the light of that article it is timely now to consider again the ability of chemical exposure to influence sensitization to common antigens.

Aurora kinases in childhood acute leukemia: the promise of aurora B as therapeutic target

We investigated the effects of targeting the mitotic regulators aurora kinase A and B in pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Aurora protein expression levels in pediatric ALL and AML patient samples were determined by western blot and reverse phase protein array. Both kinases were overexpressed in ALL and AML patients (P<0.0002), especially in E2A-PBX1-translocated ALL cases (P<0.002), compared with normal bone-marrow mononuclear cells. Aurora kinase expression was silenced in leukemic cell lines using short hairpin RNAs and locked nucleic acid-based mRNA antagonists. Aurora B knockdown resulted in proliferation arrest and apoptosis, whereas aurora A knockdown caused no or only minor growth delay. Most tested cell lines were highly sensitive to the AURKB-selective inhibitor barasertib–hydroxyquinazoline–pyrazol–anilide (AZD1152-HQPA) in the nanomolar range, as tested with an MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. But most importantly, primary ALL cells with a high aurora B protein expression, especially E2A-PBX1-positive cases, were sensitive as well. In adult AML early clinical trials, clear responses are observed with barasertib. Here we show that inhibition of aurora B, more than aurora A, has an antiproliferative and pro-apoptotic effect on acute leukemia cells, indicating that particularly targeting aurora B may offer a new strategy to treat pediatric ALL and AML.

Frequency of WT1 and 11p15 constitutional aberrations and phenotypic correlation in childhood Wilms tumour patients

INTRODUCTION

In 9-17% of Wilms tumour patients a predisposing syndrome is present, in particular WT1-associated syndromes and overgrowth syndromes. Constitutional WT1 mutations or epigenetic changes on chromosome 11p15 have also been described in Wilms tumour patients without phenotypic abnormalities. Thus, the absence of phenotypic abnormalities does not exclude the presence of a genetic predisposition, suggesting that more Wilms tumour patients may have a constitutional abnormality. Therefore, we investigated the frequency of constitutional aberrations in combination with phenotype.

PATIENTS & METHODS

Clinical genetic assessment, as well as molecular analysis of WT1 and locus 11p15 was offered to a single-centre cohort of 109 childhood Wilms tumour patients.

RESULTS

Twelve patients (11%) had a WT1 aberration and eight patients (8%) had an 11p15 aberration. Of the 12 patients with a WT1 aberration, four had WAGR syndrome (Wilms tumor, aniridia, genitourinary malformations and mental retardation), one had Denys-Drash syndrome, four had genitourinary anomalies without other syndromic features and three had bilateral disease with stromal-predominant histology at young age without congenital anomalies. Of the eight patients with an 11p15 aberration, four had Beckwith-Wiedemann syndrome (BWS), two had minor features of BWS and two had no stigmata of BWS or hemihypertrophy.

CONCLUSION

Constitutional WT1 or 11p15 aberrations are frequent in Wilms tumour patients and careful clinical assessment can identify the majority of these patients. Therefore, we would recommend offering clinical genetic counselling to all Wilms tumour patients, as well as molecular analysis to patients with clinical signs of a syndrome or with features that may indicate a constitutional WT1 or 11p15 aberration.

Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers according to their potency, without the use of animals. Within the Sens-it-iv EU Frame Programme 6 funded Integrated Project (LSHB-CT-2005-018681), a number of in vitro, human cell based assays were developed which, when optimized and used in an integrated testing strategy, may be able to distinguish sensitizers from non-sensitizers. This study describes two of these assays, which when used in a tiered strategy, may be able to identify contact sensitizers and also to quantify sensitizer potency. Tier 1 is the human keratinocyte NCTC2544 IL-18 assay and tier 2 is the Epidermal Equivalent potency assay. The aim of this study is to show the transferability of the two-tiered approach with training chemicals: 3 sensitizers (DNCB, resorcinol, pPD) and 1 non sensitizer (lactic acid) in tier 1 and 2 sensitizers with different potency in tier 2 (DNCB; extreme and resorcinol; moderate). The chemicals were tested in a non-coded fashion. Here we describe the transferability to naïve laboratories, the establishment of the standard operating procedure, critical points, acceptance criteria and project management. Both assays were successfully transferred to laboratories that had not performed the assays previously. The two tiered approach may offer an unique opportunity to provide an alternative method to the Local Lymph Node Assay (LLNA). These assays are both based on the use of human keratinocytes, which have been shown over the last two decades, to play a key role in all phases of skin sensitization.

Outcome in children with Down's syndrome and acute lymphoblastic leukemia: role of IKZF1 deletions and CRLF2 aberrations

Children with Down's syndrome (DS) have an increased risk of developing acute lymphoblastic leukemia (ALL) and have a low frequency of established genetic aberrations. We aimed to determine which genetic abnormalities are involved in DS ALL. We studied the frequency and prognostic value of deletions in B-cell development genes and aberrations of janus kinase 2 (JAK2) and cytokine receptor-like factor 2 (CRLF2) using array-comparative genomic hybridization, and multiplex ligation-dependent probe amplification in a population-based cohort of 34 Dutch Childhood Oncology Group DS ALL samples. A population-based cohort of 88 DS samples from the UK trials was used to validate survival estimates for IKZF1 and CRLF2 abnormalities. In total, 50% of DS ALL patients had ≥1 deletion in the B-cell development genes: PAX5 (12%), VPREB1 (18%) and IKZF1 (35%). JAK2 was mutated in 15% of patients, genomic CRLF2 rearrangements in 62%. Outcome was significantly worse in patients with IKZF1 deletions (6-year event-free survival (EFS) 45 ± 16% vs 95 ± 4%; P=0.002), which was confirmed in the validation cohort (6-year EFS 21 ± 12% vs 58 ± 11%; P=0.002). This IKZF1 deletion was a strong independent predictor for outcome (hazard ratio EFS 3.05; P=0.001). Neither CRLF2 nor JAK2 were predictors for worse prognosis. If confirmed in prospective series, IKZF1 deletions may be used for risk-group stratification in DS ALL.

Elevated S100A8/S100A9 expression causes glucocorticoid resistance in MLL-rearranged infant acute lymphoblastic leukemia

MLL-rearranged acute lymphoblastic leukemia (ALL) in infants is characterized by a poor clinical outcome and resistance to glucocorticoids (for example, prednisone and dexamethasone). As both the response to prednisolone in vitro and prednisone in vivo are predictive for clinical outcome, understanding and overcoming glucocorticoid resistance remains an essential step towards improving prognosis. Prednisolone-induced apoptosis depends on glucocorticoid-evoked Ca(2+) fluxes from the endoplasmic reticulum towards the mitochondria. Here, we demonstrate that in MLL-rearranged infant ALL, over-expression of S100A8 and S100A9 is associated with failure to induce free-cytosolic Ca(2+) and prednisolone resistance. Furthermore, we demonstrate that enforced expression of S100A8/S100A9 in prednisolone-sensitive MLL-rearranged ALL cells, rapidly leads to prednisolone resistance as a result of S100A8/S100A9 mediated suppression of prednisolone-induced free-cytosolic Ca(2+) levels. In addition, the Src kinase inhibitor PP2 markedly sensitized MLL-rearranged ALL cells otherwise resistant to prednisolone, via downregulation of S100A8 and S100A9, which allowed prednisolone-induced Ca(2+) fluxes to reach the mitochondria and trigger apoptosis. On the basis of this novel mechanism of prednisolone resistance, we propose that developing more specific S100A8/S100A9 inhibitors may well be beneficial for prednisolone-resistant MLL-rearranged infant ALL patients.

Pharmacology and immune modulating properties of 5-androstene-3β,7β,17β-triol, a DHEA metabolite in the human metabolome

Androst-5-ene-3β,7β,17β-triol (βAET) is an anti-inflammatory metabolite of DHEA that is found naturally in humans, but in rodents only after exogenous DHEA administration. Unlike DHEA, C-7-oxidized DHEA metabolites cannot be metabolized into potent androgens or estrogens, and are not peroxisome proliferators in rodents. The objective of our current studies was to characterize the pharmacology of βAET to enable clinical trials in humans. The pharmacology of βAET was characterized by pharmacokinetics, drug metabolism, nuclear hormone receptor interactions, androgenicity, estrogenicity, and systemic toxicity studies. βAET's acute anti-inflammatory activity and immune modulating characteristics were measured in vitro in RAW264.7 cells and in vivo in murine models with parenteral administration. βAET was rapidly metabolized and cleared from circulation in mice and monkeys. βAET was weakly androgenic and estrogenic in immature rodents, but not bound by androgen, estrogen, progesterone, or glucocorticoid nuclear hormone receptors. βAET did not induce peroxisome proliferation, nor was it systemically toxic or trophic for sex hormone responsive tissues in mature rats and monkeys. βAET significantly attenuated acute inflammation both in vitro and in vivo, augmented immune responses in adult mice, and reversed immune senescence in aged mice. βAET may contribute to the anti-inflammatory activity in rodents attributed to DHEA. Unlike DHEA, βAET's anti-inflammatory activity cannot be ascribed to activation of PPARs, androgen, or estrogen nuclear hormone receptors. Exogenous βAET is unlikely to produce untoward toxicity or hormonal perturbations in humans.

Alterations in regulatory T-cells: rediscovered pathways in immunotoxicology

In addition to the effector T-cells subsets, T-cells can also differentiate into cells that play a suppressive or regulatory role in adaptive immune responses. The cell types currently identified as regulatory T-cells (T(regs)) include natural or thymic-derived T(regs), T-cells which express Foxp3(+)CD25(+)CD4(+) and can suppress immune responses to autoreactive T-cells, as well as inducible T(regs), that are generated from naïve T-cells in the periphery after interaction with antigens presented by dendritic cells. Inducible T(regs) include T(H)3 cells, T(r)1 cells, and Foxp3(+)-inducible T(regs). T(regs) have been shown to be critical in the maintenance of immune responses and T-cell homeostasis. These cells play an important role in suppressing responses to self-antigens and in controlling inappropriate responses to non-self-antigens, such as commensal bacteria or food in the gut. For example, depletion of CD4(+)CD25(+) T(regs) from mice resulted in the development of multi-organ autoimmune diseases. CD4(+)CD25(+) T(regs) and/or IL-10-producing T(r)1 cells are capable of suppressing or attenuating T(H)2 responses to allergens. Moreover, adoptive transfer of CD4(+)CD25(+) T(regs) from healthy to diseased animals resulted in the prevention or cure of certain autoimmune diseases, and was able to induce transplantation tolerance. Clinical improvement seen after allergen immunotherapy for allergic diseases such as rhinitis and asthma is associated with the induction of IL-10- and TGFβ-producing T(r)1 cells as well as FoxP3-expressing IL-10 T-cells, with resulting suppression of the T(H)2 cytokine milieu. Activation, expansion, or suppression of CD4(+)CD25(+) T(regs) in vivo by xenobiotics, including drugs, may therefore represent a relevant mechanism underlying immunotoxicity, including immunosuppression, allergic asthma, and autoimmune diseases.

Germline variation in the MTHFR and MTRR genes determines the nadir of bone density in pediatric acute lymphoblastic leukemia: a prospective study

BACKGROUND

This study aims to identify folate-metabolism-related genetic risk factors for low bone mineral density (BMD) during/after pediatric acute lymphoblastic leukemia (ALL) treatment.

PATIENTS AND METHODS

We investigated the influence of methylenetetrahydrofolate reductase (MTHFR 677C > T and 1298A > C) and methionine synthase reductase (MTRR 66A > G) single nucleotide polymorphisms (SNPs) on total body BMD (BMD(TB)) and lumbar spine BMD (BMD(LS)) in 83 patients. Homocysteine, folate and vitamin B12 were determined. BMD was measured repeatedly using dual-energy X-ray absorptiometry in patients ≥ 4 years (n = 68).

RESULTS

Carriers of the MTHFR 677 T-allele showed a lower baseline BMD(TB) than non-carriers (-0.38 SDS vs. +0.55 SDS, p = 0.01) and BMD(TB) remained lower during/after treatment. MTHFR 677C>T did not influence treatment-related loss of BMD(TB) (p = 0.39). The MTRR 66 G-allele carriers showed a trend towards a lower BMD(TB) compared with non-carriers. Combining these two SNPs, patients carrying ≥ 2 risk alleles had a significantly lower BMD(TB) (-1.40 SDS) than patients with one (-0.80 SDS) or no risk alleles (-0.31 SDS). Although carriers of the MTHFR 1298A > C had higher homocysteine levels, this SNP was not related to BMD(TB). BMD(LS) of carriers was similar to non-carriers of the investigated SNPs.

CONCLUSIONS

The MTHFR 677C>T SNP and the MTRR 66A >G SNP were identified as determinants of impaired BMD(TB) in childhood ALL patients.

CD4(+) CD25(+) T regulatory cells do not transfer oral tolerance to peanut allergens in a mouse model of peanut allergy

BACKGROUND

Recent studies have implicated CD4(+) CD25(+) regulatory T cells (nTregs) in the maintenance of tolerance to oral antigens and in the regulation of the food allergic IgE response.

OBJECTIVE

The objective was to assess if nTregs can transfer allergen-specific oral tolerance to naïve, non-TCR transgenic mice and regulate peanut extract (PE)-specific hypersensitivity responses. Additionally, the role of the regulatory cytokines IL-10 and TGF-β in the modulation of peanut-allergic sensitization was studied.

METHODS

CD25-enriched T cells from PE-tolerant mice were adoptively transferred to recipient mice, which were subsequently sensitized to PE. Depletion of CD25(+) cells and neutralization of IL-10 and TGF-β were compared in a CH3/HeOuJ mouse model of peanut-allergic sensitization.

RESULTS

Transfer of CD25(+) Tregs-enriched cell populations did not affect the PE-specific cytokine production or PE-specific antibody levels compared with control mice but interestingly resulted in a decrease of mast cell responsiveness. On the contrary, transfer of CD25(+) Tregs-depleted cells caused an increase in non-specific cytokine production, in the absence of changes in PE-specific responses. TGF-β neutralization resulted even in a larger increase in spontaneous release of all cytokines measured (IL-4, IL-5, IL-10, IL-13, and IFN-γ), but surprisingly also to a higher PE-specific Th2-associated (IL-4, IL-5, IL-13) cytokine production compared with depletion of CD25 cells or neutralization of IL-10. Similarly, depletion of CD25 cells and TGF-β neutralization but not of IL-10 neutralization lead to an increase in PE-specific antibody levels and elevated mast cell degranulation following a PE challenge.

CONCLUSIONS AND CLINICAL RELEVANCE

We conclude that CD4(+) CD25(+) Tregs from non-transgenic-tolerant mice cannot transfer specific oral tolerance of exogenous antigens to naïve mice and are more involved in general immune suppressive mechanisms. However, we found evidence that TGF-β secreting Tregs (Th3) may play an important role.

The state of research into children with cancer across Europe: new policies for a new decade

Overcoming childhood cancers is critically dependent on the state of research. Understanding how, with whom and what the research community is doing with childhood cancers is essential for ensuring the evidence-based policies at national and European level to support children, their families and researchers. As part of the European Union funded EUROCANCERCOMS project to study and integrate cancer communications across Europe, we have carried out new research into the state of research in childhood cancers. We are very grateful for all the support we have received from colleagues in the European paediatric oncology community, and in particular from Edel Fitzgerald and Samira Essiaf from the SIOP Europe office. This report and the evidence-based policies that arise from it come at a important junction for Europe and its Member States. They provide a timely reminder that research into childhood cancers is critical and needs sustainable long-term support.