Allele-specific CRISPR-Cas9 editing of dominant epidermolysis bullosa simplex in human epidermal stem cells

Epidermolysis bullosa simplex (EBS) is a rare skin disease inherited mostly in an autosomal dominant manner. Patients display a skin fragility that leads to blisters and erosions caused by minor mechanical trauma. EBS phenotypic and genotypic variants are caused by genetic defects in intracellular proteins whose function is to provide the attachment of basal keratinocytes to the basement membrane zone and most EBS cases display mutations in keratin 5 (KRT5) and keratin 14 (KRT14) genes. Besides palliative treatments, there is still no long-lasting effective cure to correct the mutant gene and abolish the dominant negative effect of the pathogenic protein over its wild-type counterpart. Here, we propose a molecular strategy for EBS01 patient's keratinocytes carrying a monoallelic c.475/495del21 mutation in KRT14 exon 1. Through the CRISPR-Cas9 system, we perform a specific cleavage only on the mutant allele and restore a normal cellular phenotype and a correct intermediate filament network, without affecting the epidermal stem cell, referred to as holoclones, which play a crucial role in epidermal regeneration.

Conversion to mTOR Inhibitor to Reduce the Incidence of Cytomegalovirus Recurrence in Kidney Transplant Recipients Receiving Preemptive Treatment: A Prospective, Randomized Trial

BACKGROUND

Although mammalian target of rapamycin inhibitors (mTORi) are associated with a lower incidence of the first episode of cytomegalovirus (CMV) infection/disease in kidney transplant recipients receiving calcineurin inhibitors (CNIs), the efficacy and safety of the conversion from the antimetabolite to an mTORi for the prevention of CMV recurrence are unknown.

METHODS

In this single-center prospective randomized trial, low-immunological-risk, CMV-positive kidney transplant recipients receiving preemptive therapy were randomized to be converted (sirolimus [SRL]) or not (control [CTR]) immediately after the treatment of the first episode of CMV infection/disease and were followed for 12 mo. A sample size of 72 patients was calculated to demonstrate a 75% reduction in the incidence of CMV recurrence (80% power, 95% confidence level).

RESULTS

Of 3247 adult kidney transplants performed between September 13, 2015, and May 7, 2019, 1309 (40%) were treated for the first CMV infection/disease, and 72 were randomized (35 SRL and 37 CTR). In the SRL group, there were no episodes of CMV recurrence, compared with 16 patients in the CTR group (0% versus 43%; P  < 0.0001). Four patients had a second and 1 a third recurrent CMV event. Three of them were converted to SRL and did not develop any further CMV events. There were no differences in the incidence of acute rejection, drug discontinuation, kidney function, and patient and graft survival at 12 mo.

CONCLUSIONS

These data suggest that, in CMV-positive kidney transplant recipients, the conversion from an antiproliferative drug to SRL after the first CMV episode is an effective and safe strategy for recurrent episodes.

Canonical and uncanonical pathogenic germline variants in colorectal cancer patients by next-generation sequencing in a European referral center

BACKGROUND

Despite increasing use of next-generation sequencing (NGS), data concerning the gain in germline pathogenic variants (PVs) remain scanty, especially with respect to uncanonical ones. We aimed to verify the impact of different cancer predisposition genes (CPGs) on colorectal cancer (CRC) in patients referred for genetic evaluation.

MATERIALS AND METHODS

We enrolled for NGS, by Illumina TruSight Cancer panel comprising 94 CPGs, 190 consecutive subjects referred for microsatellite instability (MSI) CRC, polyposis, and/or family history.

RESULTS

Overall, 51 (26.8%) subjects carried 64 PVs; PVs coexisted in 4 (7.8%) carriers. PVs in mismatch repair (MMR) genes accounted for one-third of variant burden (31.3%). Four Lynch syndrome patients (20%) harbored additional PVs (HOXB13, CHEK2, BRCA1, NF1 plus BRIP1); such multiple PVs occurred only in subjects with PVs in mismatch syndrome genes (4/20 versus 0/31; P = 0.02). Five of 22 (22.7%) patients with MSI cancers but wild-type MMR genes harbored PVs in unconventional genes (FANCL, FANCA, ATM, PTCH1, BAP1). In 10/63 patients (15.9%) with microsatellite stable CRC, 6 had MUTYH PVs (2 being homozygous) and 4 exhibited uncanonical PVs (BRCA2, BRIP1, MC1R, ATM). In polyposis, we detected PVs in 13 (25.5%) cases: 5 (9.8%) in APC, 6 (11.8%) with biallelic PVs in MUTYH, and 2 (3.9%) in uncanonical genes (FANCM, XPC). In subjects tested for family history only, we detected two carriers (18.2%) with PVs (ATM, MUTYH).

CONCLUSION

Uncanonical variants may account for up to one-third of PVs, underlining the urgent need of consensus on clinical advice for incidental findings in cancer-predisposing genes not related to patient phenotype.

Patient-derived organoids (PDOs) as a novel in vitro model for neuroblastoma tumours

BACKGROUND

Neuroblastoma (NB) is a paediatric tumour of the sympathetic nervous system. Half of all cases are defined high-risk with an overall survival less than 40% at 5 years from diagnosis. The lack of in vitro models able to recapitulate the intrinsic heterogeneity of primary NB tumours has hindered progress in understanding disease pathogenesis and therapy response.

METHODS

Here we describe the establishment of 6 patient-derived organoids (PDOs) from cells of NB tumour biopsies capable of self-organising in a structure resembling the tissue of origin.

RESULTS

PDOs recapitulate the histological architecture typical of the NB tumour. Moreover, PDOs expressed NB specific markers such as neural cell adhesion molecules, NB84 antigen, synaptophysin (SYP), chromogranin A (CHGA) and neural cell adhesion molecule NCAM (CD56). Analyses of whole genome genotyping array revealed that PDOs maintained patient-specific chromosomal aberrations such as MYCN amplification, deletion of 1p and gain of chromosome 17q. Furthermore, the PDOs showed stemness features and retained cellular heterogeneity reflecting the high heterogeneity of NB tumours.

CONCLUSIONS

We were able to create a novel preclinical model for NB exhibiting self-renewal property and allowing to obtain a reservoir of NB patients' biological material useful for the study of NB molecular pathogenesis and to test drugs for personalised treatments.

HLA alleles in renal transplant recipients with nonmelanoma skin cancer in southeastern Brazil

BACKGROUND

Renal transplant recipients are submitted to immunosuppression to avoid graft rejection, which makes them susceptible to various conditions. Furthermore, these individuals present malignant tumors more frequently than the general population, including nonmelanoma skin cancer. The individual genetic basis that acts in the pathogenesis of cutaneous cancer may present a protection or susceptibility factor for disease development. One of these factors is the HLA complex.

OBJECTIVE

To investigate HLA alleles association to the occurrence of nonmelanoma skin cancer in renal transplant recipients from São Paulo State.

METHODS

A total of 213 patients (93 renal transplant recipients with nonmelanoma skin cancer and 120 renal transplant recipients without nonmelanoma skin cancer) were evaluated by retrospective and cross-sectional study. Epidemiological, clinical and HLA typing data were found in databases. HLA class I (A, B) and class II (DR) alleles were compared to establish their association with nonmelanoma skin cancer.

RESULTS

Comparing renal transplant recipients with and without nonmelanoma skin cancer, the HLA-B*13 allele was associated with higher risk of developing nonmelanoma skin cancer while B*45 and B*50 alleles were associated with protection.

STUDY LIMITATIONS

The HLA A, B and DR alleles identification for the kidney transplantation routine is done by low and medium resolution techniques that do not allow discrimination of specific alleles.

CONCLUSION

The involvement of HLA alleles in nonmelanoma skin cancer in renal transplant recipients was confirmed in this study. Renal transplant recipients with HLA-B*13 showed higher risk for developing a skin cancer (OR= 7.29) and should be monitored for a long period of time after transplantation.

The current burden of cytomegalovirus infection in kidney transplant recipients receiving no pharmacological prophylaxis

Cytomegalovirus (CMV) infection in kidney transplantation has changed its clinical spectrum, mostly due to the current and more effective immunosuppression. In the absence of preventive strategies it is associated with significant morbi-mortality.

OBJECTIVE

This study evaluated the incidence of CMV events and its effect on outcomes of kidney transplantation in recipients without pharmacological prophylaxis or targeted preemptive treatment.

RESULTS

The study cohort comprised 802 recipients of kidney transplants between 04/30/2014 and 04/30/2015. The majority received induction with anti-thymocyte globulin (81.5%), tacrolimus and prednisone in combination with either mycophenolate (46.3%) or azathioprine (53.7%). The overall incidence of CMV events was 42% (58.6% infection and 41.4% disease). Patients with CMV showed higher incidence of first treated acute rejection (19 vs. 11%, p = 0,001) compared with those without CMV but no differences in graft loss, death or loss to follow-up. The incidence of delayed graft function was higher (56% vs. 37%, p = 0.000) and the eGFR at 1 (41 ± 21 vs. 54 ± 28 ml/min, p = 0.000) and 12 months (50 ± 19 vs. 61 ± 29 ml/min, p = 0.000) were lower in patients with CMV. Recipients age (OR = 1.03), negative CMV serology (OR = 5.21) and use of mycophenolate (OR = 1.67) were associated with increased risk of CMV. Changes in immunosuppression was more often in patients with CMV (63% vs. 31%, p = 0.000).

CONCLUSION

the incidence of CMV events was high and associated with higher incidence of acute rejection and changes in immunosuppression. Besides traditional risk factors, renal function at 1 month was independently associated with CMV infection.

The effect of anti-thymocyte globulin and everolimus on the kinetics of cytomegalovirus viral load in seropositive kidney transplant recipients without prophylaxis

BACKGROUND

The use of mTOR inhibitors is associated with lower incidence of CMV infections but its effect on viral load has not been investigated.

AIMS, MATERIALS AND METHODS

This post-hoc analysis included data from 273 CMV seropositive kidney transplant recipients randomized to receive anti-thymocyte globulin and everolimus (rAGT/TAC/EVR, n = 81), basiliximab and everolimus (BAS/TAC/EVR, n = 97) or basiliximab and mycophenolate (BAS/TAC/MPS, n = 95). All patients received tacrolimus (TAC) and corticosteroids. Preemptive CMV therapy based on weekly pp65 antigenemia test was used during the first 6 months. Blinded weekly CMV DNAemia was compared among the groups.

RESULTS

The proportion of patients with undetectable CMV DNAemia (23.4% vs 56.7% vs 22.1%, P < .001) was higher in the BAS/TAC/EVR. The median number of study visits with positive CMV DNAemia (2.0 vs 0.0 vs 4.6, rATG/EVR vs BAS/MPS, P = .354; BAS/EVR vs BAS/MPS, P < .0001; rATG/EVR vs BAS/EVR, P < .001) were lower in the BAS/TAC/EVR. The proportion of patients with positive CMV DNAemia who were not treat for CMV infection/disease based on pp65 antigenemia was higher in rATG/TAC/EVR group (74.1% vs 36.1% vs 44.2%, P < .001) but mean CMV DNAemia was comparable to BAS/TAC/EVR and lower than BAS/TAC/MPS (8536 ± 15 899 vs 7975 ± 17 935 vs 16 965 ± 37 694 copies/mL, P < .05), respectively. The proportion of patients with CMV DNAemia below 5000 copies/mL was higher in patients receiving EVR (74.1% vs 83.5% vs 50.0%, P = .000), respectively.

DISCUSSION AND CONCLUSION

These data suggest that mTOR inhibitors reduce the incidence of CMV infection by limiting CMV viral replication.

N-MYC and C-MYC Oncogenes Amplification in Medulloblastomas. Evidence of Particularly Aggressive Behavior of a Tumor with C-MYC Amplification

N-myc and c-myc amplification was investigated in 27 medulloblastomas. DNA was extracted from 19 formalin fixed and paraffin embedded tumors and from fresh frozen tumor tissue in 8 other cases. The results showed no evidence of amplification of N-myc oncogene and only 1 case had a 27 fold amplification of c-myc. Cytogenetically, this neoplasm presented numerous double minute chromosomes (DMs). Moreover, it had an unusual rapidly aggressive course with massive cerebrospinal fluid dissemination unresponsive to intrathecal chemotherapy. Our results indicate a low incidence of N-myc and c-myc gene amplification in medulloblastomas, suggesting that the oncogenic mechanism in these neoplasms is not closely related to DNA gene amplification. C-myc amplification, although not frequently observed, may however provide a growth advantage for medulloblastoma cells in vivo, favoring their rapid dissemination. Medulloblastomas with c-myc activation may represent a subgroup of tumors with a more aggressive behavior.

Primary mediastinal large B-cell lymphoma: Outcome of a series of pediatric patients treated with high-dose methotrexate and cytarabine plus anti-CD20

Between 2007 and 2013, 13 children diagnosed with primary mediastinal large B-cell lymphoma (PMLBL) were treated according to a modified version of AIEOP (Associazione Italiana Ematologia Oncologia Pediatrica) LNH-97 protocol based on high-dose methotrexate, anthracyclines, and addition of anti-CD20. Ten patients achieved a continuous complete remission with front-line therapy. The overall 5-year survival was 91.7%, and event-free survival was 83.9%, with only one patient dying of progressive disease. Despite the few cases, these results demonstrate that this therapy, which includes anti-CD20, given in a multicenter setting, is feasible with acceptable toxicity in children with PMLBL.

Donor-Specific Anti-Human Leukocyte Antigens Antibodies, Acute Rejection, Renal Function, and Histology in Kidney Transplant Recipients Receiving Tacrolimus and Everolimus

BACKGROUND

This analysis compared efficacy, renal function, and histology in kidney transplant recipients receiving tacrolimus (TAC) combined with everolimus (EVR) or mycophenolate (MPS).

METHODS

This was a retrospective analysis from a randomized trial in kidney transplant recipients who received a single 3 mg/kg dose of rabbit antithymocyte globulin (r-ATG), TAC, EVR, and prednisone (PRED; r-ATG/EVR, n = 85), basiliximab (BAS), TAC, EVR, and PRED (BAS/EVR, n = 102) or BAS, TAC, MPS, and PRED (BAS/MPS, n = 101). We evaluated the incidence of de novo donor-specific anti-human leukocyte antigens antibodies (DSA) and histology on protocol biopsies at 12 months, and the incidence of acute rejection, estimated glomerular filtration rate (eGFR) and proteinuria at 36 months.

RESULTS

At 12 months, there were no differences in de novo DSA (6.4 vs. 3.4 vs. 5.5%) or in subclinical inflammation (2.0 vs. 4.8 vs. 10.2%), interstitial fibrosis/tubular atrophy (57.1 vs. 58.5 vs. 53.8%) and C4d deposition (2.0 vs. 7.3 vs. 2.6%). At 36 months, there were no differences in the incidence of treatment failure (19.0 vs. 27.7 vs. 27.7%, p = 0.186), first biopsy-proven acute rejection (9.5 vs. 21.8 vs. 16.8%, p = 0.073), and urine protein/creatinine ratios (0.53 ± 1.05 vs. 0.62 ± 0.75 vs. 0.71 ± 1.24). eGFR was lower in the BAS/EVR compared to that in the BAS/MPS group (53.4 ± 20.9 vs. 50.8 ± 19.5 vs. 60.7 ± 21.2 mL/min/1.73 m2, p = 0.017) but comparable using a sensitive analysis (49.5 ± 23 vs. 47.5 ± 22.6 vs. 53.6 ± 27.8 mL/min/1.73 m2, p = 0.207).

CONCLUSION

In this cohort, the use of EVR and reduced TAC concentrations were associated with comparable efficacy, renal function, and histological parameters compared to the standard-of-care immunosuppressive regimen.

Characterization of children with FLT3-ITD acute myeloid leukemia: a report from the AIEOP AML-2002 study group

Recurrent molecular markers have been routinely used in acute myeloid leukemia (AML) for risk assessment at diagnosis, whereas their post-induction monitoring still represents a debated issue. We evaluated the prognostic value and biological impact of minimal residual disease (MRD) and of the allelic ratio (AR) of FLT3-internal-tandem duplication (ITD) in childhood AML. We retrospectively screened 494 children with de novo AML for FLT3-ITD mutation, identifying 54 harboring the mutation; 51% of them presented high ITD-AR at diagnosis and had worse event-free survival (EFS, 19.2 versus 63.5% for low ITD-AR, <0.05). Forty-one percent of children with high levels of MRD after the 1st induction course, measured by a patient-specific real-time-PCR, had worse EFS (22.2 versus 59.4% in low-MRD patients, P<0.05). Next, we correlated these parameters with gene expression, showing that patients with high ITD-AR or persistent MRD had characteristic expression profiles with deregulated genes involved in methylation and acetylation. Moreover, patients with high CyclinA1 expression presented an unfavorable EFS (20.3 versus 51.2% in low CyclinA1 group, P<0.01). Our results suggest that ITD-AR levels and molecular MRD should be considered in planning clinical management of FLT3-ITD patients. Different transcriptional activation of epigenetic and oncogenic profiles may explain variability in outcome among these patients, for whom novel therapeutic approaches are desirable.

Calcineurin and GSK-3 inhibition sensitizes T-cell acute lymphoblastic leukemia cells to apoptosis through X-linked inhibitor of apoptosis protein degradation

The calcineurin (Cn)-nuclear factor of activated T cells signaling pathway is critically involved in many aspects of normal T-cell physiology; however, its direct implication in leukemogenesis is still ill-defined. Glycogen synthase kinase-3β (GSK-3β) has recently been reported to interact with Cn in neuronal cells and is implicated in MLL leukemia. Our biochemical studies clearly demonstrated that Cn was able to interact with GSK-3β in T-cell acute lymphoblastic leukemia (T-ALL) cells, and that this interaction was direct, leading to an increased catalytic activity of GSK-3β, possibly through autophosphorylation of Y216. Sensitivity to GSK-3 inhibitor treatment correlated with altered GSK-3β phosphorylation and was more prominent in T-ALL with Pre/Pro immunophenotype. In addition, dual Cn and GSK-3 inhibitor treatment in T-ALL cells promoted sensitization to apoptosis through proteasomal degradation of X-linked inhibitor of apoptosis protein (XIAP). Consistently, resistance to drug treatments in primary samples was strongly associated with higher XIAP protein levels. Finally, we showed that dual Cn and GSK-3 inhibitor treatment in vitro and in vivo is effective against available models of T-ALL, indicating an insofar untapped therapeutic opportunity.

Focal nodular hyperplasia of the liver: an emerging complication of hematopoietic SCT in children

Hepatic focal nodular hyperplasia (FNH) is a nonmalignant condition rarely affecting children previously treated for cancer, especially those who received hematopoietic SCT (HSCT). Some aspects of its pathogenesis still remain unclear and a strong association with specific risk factors has not yet been identified. We report here a single institution's case series of 17 patients who underwent HSCT and were diagnosed with FNH, analyzing retrospectively their clinical features and the radiological appearance of their hepatic lesions. We aimed to compare the diagnostic accuracy of ultrasound (US) and magnetic resonance imaging (MRI) and to explore the role of transient elastography (FibroScan) to evaluate the degree of hepatic fibrosis in FNH patients. Our analysis showed an association of FNH with age at transplant ⩽12 years (hazard ratio (HR) 9.10); chronic GVHD (HR 2.99); hormone-replacement therapy (HR 4.02) and abdominal radiotherapy (HR 4.37). MRI proved to be a more accurate diagnostic tool compared with US. Nine out of 12 patients who underwent FibroScan showed hepatic fibrosis. Our study points out that FNH is an emerging complication of HSCT, which requires a lifelong surveillance to follow its course in cancer patients.

Lymphocytes subsets reference values in childhood

Immunophenotyping of blood lymphocyte subsets and activation markers is a basic tool in the diagnostic process of primary immunodeficiency diseases, its use becoming more and more widespread as the knowledge about these illnesses increases. However, the availability of reliable reference values, which need to be age-matched for the pediatric population, is a pre-requisite for the reliable interpretation of immunophenotyping data. Aim of this study is to analyze the lymphocyte subsets and activation markers distribution in children aged 0-18 years referring to the University Hospital of Padova and to create age-matched reference values expressed by percentiles, thus providing a valuable guideline for the interpretation of the immunophenotype.

Validation of flow cytometric phospho-STAT5 as a diagnostic tool for juvenile myelomonocytic leukemia

To diagnose juvenile myelomonocytic leukemia (JMML) is sometimes challenging, because around 10% of patients lack molecular abnormalities affecting Ras-MAPK (mitogen-activated protein kinase) pathway and other diseases such as cytomegalovirus infection can mimic clinical signs of JMML. In order to validate a phospho-specific flow cytometry assay assessing phospho-signal transducer and activator of transcription factor 5 (p-STAT5) as a new diagnostic tool for JMML, we examined 22 samples from children with JMML and 47 controls. CD33+/CD34+ cells from 22 patients with JMML showed hyperphosphorylation of STAT5 induced by sub-saturating doses of granulocyte-macrophage colony-stimulating factor (GM-CSF). Using a training set of samples (11 JMML and 23 controls), we identified a threshold for p-STAT5-positive after stimulation with 0.1 ng/ml GM-CSF (17.17%) that discriminates JMML from controls. This threshold was validated in an independent series (11 JMML, 24 controls and 7 cases with diseases other than JMML) where we demonstrated that patients with JMML could be distinguished from other subjects with a sensitivity of 91% (confidence interval (CI) 59–100%) and a specificity of 87% (CI 70–96%). Positive and negative predictive values were 71% (CI 42–92%) and 96% (CI 82–100%), respectively. In conclusion, flow cytometric p-STAT5 profiling is a reliable diagnostic tool for identifying patients with JMML and can contribute to consistency of current diagnostic criteria.

Early expression of the fractalkine receptor CX3CR1 in pancreatic carcinogenesis

BACKGROUND

In pancreatic ductal adenocarcinoma (PDAC), fractalkine receptor CX3CR1 contributes to perineural invasion (PNI). We investigated whether CX3CR1 expression occurs early in PDAC and correlates with tumour features other than PNI.

METHODS

We studied CX3CR1 and CX3CL1 expression by immunohistochemistry in 104 human PDAC and coexisting Pancreatic Intraepithelial Neoplasia (PanIN), and in PdxCre/LSL-Kras(G12D) mouse model of PDAC. CX3CR1 expression in vitro was studied by a spheroid model, and in vivo by syngenic mouse graft of tumour cells.

RESULTS

In total, 56 (53.9%) PDAC expressed CX3CR1, 70 (67.3%) CX3CL1, and 45 (43.3%) both. CX3CR1 expression was independently associated with tumour glandular differentiation (P=0.005) and PNI (P=0.01). Pancreatic Intraepithelial Neoplasias were more frequently CX3CR1+ (80.3%, P<0.001) and CX3CL1+ (86.8%, P=0.002) than matched cancers. The survival of PDAC patients was better in those with CX3CR1+ tumour (P=0.05). Mouse PanINs were also CX3CR1(+) and -CL1(+). In vitro, cytokines significantly increased CX3CL1 but not CX3CR1 expression. Differently, CX3CR1 was upregulated in tumour spheroids, and in vivo only in well-differentiated tumours.

CONCLUSION

Tumour differentiation, rather than inflammatory signalling, modulates CX3CR1 expression in PanINs and PDAC. CX3CR1 expression pattern suggests its early involvement in PDAC progression, outlining a potential target for interfering with the PanIN transition to invasive cancer.

Improvement of the accuracy of noise measurements by the two-amplifier correlation method

We present a novel method for device noise measurement, based on a two-channel cross-correlation technique and a direct "in situ" measurement of the transimpedance of the device under test (DUT), which allows improved accuracy with respect to what is available in the literature, in particular when the DUT is a nonlinear device. Detailed analytical expressions for the total residual noise are derived, and an experimental investigation of the increased accuracy provided by the method is performed.

Wnt activation promotes neuronal differentiation of glioblastoma

One of the biggest challenges in tumour research is the possibility to reprogram cancer cells towards less aggressive phenotypes. In this study, we reprogrammed primary Glioblastoma multiforme (GBM)-derived cells towards a more differentiated and less oncogenic phenotype by activating the Wnt pathway in a hypoxic microenvironment. Hypoxia usually correlates with malignant behaviours in cancer cells, but it has been recently involved, together with Wnt signalling, in the differentiation of embryonic and neural stem cells. Here, we demonstrate that treatment with Wnt ligands, or overexpression of β-catenin, mediate neuronal differentiation and halt proliferation in primary GBM cells. An hypoxic environment cooperates with Wnt-induced differentiation, in line with our finding that hypoxia inducible factor-1α (HIF-1α) is instrumental and required to sustain the expression of β-catenin transcriptional partners TCF-1 and LEF-1. In addition, we also found that Wnt-induced GBM cell differentiation inhibits Notch signalling, and thus gain of Wnt and loss of Notch cooperate in the activation of a pro-neuronal differentiation program. Intriguingly, the GBM sub-population enriched of cancer stem cells (CD133⁺ fraction) is the primary target of the pro-differentiating effects mediated by the crosstalk between HIF-1α, Wnt, and Notch signalling. By using zebrafish transgenics and mutants as model systems to visualize and manipulate in vivo the Wnt pathway, we confirm that Wnt pathway activation is able to promote neuronal differentiation and inhibit Notch signalling of primary human GBM cells also in this in vivo set-up. In conclusion, these findings shed light on an unsuspected crosstalk between hypoxia, Wnt and Notch signalling in GBM, and suggest the potential to manipulate these microenvironmental signals to blunt GBM malignancy.

Rare frequencey of point mutations for codon 12, 13 and 61 of ras gene in italian neuroblastoma

Single point mutations of ras oncogenes are found in many tumors and contribute to the pathogenesis of the cancer. The product of the ras gene, p21 protein, was found expressed in several neuroblastoma tissues. However, the role of ras gene in this tumor has yet to be clarified. To contribute to the understanding of the ras activation, 79 fresh biopsies of neuroblastoma were studied to investigate the possibility that ras would be activated by point mutation. Analysis of H-ras and N-ras was performed by means of PCR and SSO, while K-ras mutations were detected by multiplex-ASPCR. None of the neuroblastomas examined showed H- or K-ras activation, while N-ras mutations were demonstrated in only three patients (3,7%). N-myc oncogene is amplified in a substantial number of patients with neuroblastoma. N-myc amplification was studied by Southern blot technique. N-myc amplification was demonstrated in 13.2% of patients less than 1 year of age at diagnosis and 23% of older children. Two of the patients (one stage I and one stage IVs) with N-ras mutation and without N-myc amplification had a good outcome, while the third (stage IVs) with N-myc amplification had a poor prognosis. These results suggest that ras activation is a rare event in both amplified and non-amplified neuroblastoma tumors and that N-ras activation was not involved in the clinical outcome of these patients. Moreover, our data suggest that p21 expression is induced by a post-transcriptional activation.

Notch3-mediated regulation of MKP-1 levels promotes survival of T acute lymphoblastic leukemia cells

Activation of the Notch pathway occurs commonly in T acute lymphoblastic leukemia (T-ALL) because of mutations in Notch1 or Fbw7 and is involved in the regulation of cell proliferation and survival. Deregulated Notch3 signalling has also been shown to promote leukemogenesis in transgenic mice, but the targets of Notch3 in human T-ALL cells remain poorly characterized. Here, we show that Notch3 controls levels of mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1). In a model of T-ALL cell dormancy, both Notch3 activation and MKP-1 expression were upregulated in aggressive compared with dormant tumors, and this inversely correlated with the levels of phosphorylated p38 and extracellular signal-regulated kinase1/2 (ERK1/2) MAPKs, two canonical MKP-1 targets. We demonstrate that MKP-1 protein levels are regulated by Notch3 in T-ALL cell lines because its silencing by RNA interference or treatment with γ-secretase inhibitors induced strong MKP-1 reduction whereas activation of Notch3 signalling had the opposite effect. Furthermore, MKP-1 has an important role in T-ALL cell survival because its attenuation by short hairpin RNA significantly increased cell death under stress conditions. This protective function has a key role in vivo, as MKP-1-deficient cells showed impaired tumorigenicity. These results elucidate a novel mechanism downstream of Notch3 that controls the survival of T-ALL cells.

Long-term results of the Italian Association of Pediatric Hematology and Oncology (AIEOP) Studies 82, 87, 88, 91 and 95 for childhood acute lymphoblastic leukemia

We analyzed the long-term outcome of 4865 patients treated in Studies 82, 87, 88, 91 and 95 for childhood acute lymphoblastic leukemia (ALL) of the Italian Association of Pediatric Hematology and Oncology (AIEOP). Treatment was characterized by progressive intensification of systemic therapy and reduction of cranial radiotherapy. A progressive improvement of results with reduction of isolated central nervous system relapse rate was obtained. Ten-year event-free survival increased from 53% in Study 82 to 72% in Study 95, whereas survival improved from 64 to 82%. Since 1991, all patients were treated according to Berlin-Frankfurt-Muenster (BFM) ALL treatment strategy. In Study 91, reduced treatment intensity (25%) yielded inferior results, but intensification of maintenance with high-dose (HD)-L-asparaginase (randomized) allowed to compensate for this disadvantage; in high-risk patients (HR, 15%), substitution of intensive polychemotherapy blocks for conventional BFM backbone failed to improve results. A marked improvement of results was obtained in HR patients when conventional BFM therapy was intensified with three polychemotherapy blocks and double delayed intensification (Study 95). The introduction of minimal residual disease monitoring and evaluation of common randomized questions by AIEOP and BFM groups in the protocol AIEOP-BFM-ALL 2000 are expected to further ameliorate treatment of children with ALL.

DNA copy-number abnormalities do not occur in infant ALL with t(4;11)/MLL-AF4

The pathogenesis of infant acute lymphoblastic leukemia (ALL) is still not well defined. Short latency to leukemia and very high concordance rate for ALL in Mixed-Lineage Leukemia (MLL)-positive infant twins suggest that the MLL rearrangement itself could be sufficient for overt leukemia. Attempts to generate a suitable mouse model for MLL-AF4-positive ALL did not thoroughly resolve the issue of whether cooperating mutations are required to reduce latency and to generate overt leukemia in vivo. In this study, we applied single-nucleotide polymorphism array technology to perform genomic profiling of 28 infant ALL cases carrying t(4;11) to detect MLL-cooperating aberrations hidden to conventional techniques and to gain new insights into infant ALL pathogenesis. In contrast to pediatric, adolescent and adult ALL cases, the MLL rearrangement in infant ALL is associated with an exceptionally low frequency of copy-number abnormalities, thus confirming the unique nature of this disease. By contrast, additional genetic aberrations are acquired at disease relapse. Small-segmental uniparental disomy traits were frequently detected, mostly constitutional, and widely distributed throughout the genome. It can be argued that the MLL rearrangement as a first hit, rather than inducing the acquisition of additional genetic lesions, has a major role to drive and hasten the onset of leukemia.

Glioblastoma-derived cells exhibit differential responses to glycolysis inhibition under hypoxia

e13031

It has been suggested that oxygen tension is a crucial component of the brain tumor niche, as hypoxia positively correlates with tumor aggressiveness and over-activity of hypoxia inducible factor-1α (HIF-1α) reinforces tumor progression. Furthermore, hypoxia has been implicated in the regulation of several signaling pathways (Notch, BMP), angiogenesis and importantly, glucose metabolism. Here we investigate the effects mediated by in vitro glycolysis inhibition by using 2-deoxyglucose (2-DG) in glioblastoma (GBM) derived cells maintained under two different oxygen tensions, a lowered oxygen tension (2%) versus a higher non-physiological (20%). GBM account for 50% of all gliomas and arise after age 50 in most patients and it has been seen that younger patients tend to have a better prognosis than the elderly. Our results show that adult GBM displaying a highly immature phenotype manifested the highest resistance to glucose deprivation. Furthermore, increase of multi-drug resistant cell fraction, described as side population, occurred following 2-DG treatment, but only under hypoxia. Neuronal committed precursors were selected by 2-DG, but these effects were mitigated by hypoxia. Also, hypoxia inhibits the mitochondria-controlled apoptosis induced by 2-DG, by conferring cell resistance through progressive activation of pro-survival NF-kB and induction of tumor cell autophagy. Importantly, HIF-1α level reduction and proline hydroxylase 2 (PHD2) upregulation occurred following 2-DG treatment even under hypoxia, and this may depend on reactive oxygen species reduction. These results indicate differences in tumor cells behavior that may be predictive of cell response to therapy aiming to limit glucose uptake or glucose metabolism.

No significant financial relationships to disclose.

Association of time to leukemia (TTL) in NOD/SCID mice with expression of apoptosis regulators in pediatric ALL

10042

Background: Acute lymphoblastic leukemia (ALL) is the most frequent malignant disease in childhood. Although advances in therapy have led to improved long term survival, relapse remains a major challenge. In a recent study we transplanted pediatric leukemia samples from newly diagnosed BCP-ALL patients into NOD/SCID mice. Time to leukemia (TTL) was analyzed for each patient sample as time from transplant to overt leukemia in the recipients. Patients whose leukemia cells engrafted rapidly showed a clearly inferior relapse free survival in contrast to patient samples with prolonged in vivo growth. Multivariate analysis showed an almost 45- fold increased risk for relapse in patients with short TTL. Methods: Gene expression profiles of ALL samples (N = 14) with short versus long TTL in the xenograft model were analyzed using a human whole genome array (Affymetrix U133 Plus 2.0) correlating gene expression values (relative expression) to the time from transplant to manifestation of leukemia in the NOD/SCID mice (TTL, in weeks) by quantitative traits analysis (QTA). Results: Among 5 genes significantly correlated (Spearman correlation, P < .0001) XIAP-associated factor 1 (XAF1) was found to be up-regulated in patients with long TTL. XAF1 abrogates the inhibitory effect of XIAP on caspase-3 thereby sensitizing for apoptosis. In accordance to this caspase-3 activation was also found to be up-regulated in patients with long TTL. Patient samples exhibiting a short time to overt leukemia in the xenotransplant model associated with poor relapse free survival showed down-regulated XAF1 and impaired caspase-3 activation leading to decreased apoptosis of the leukemia cells. Conclusions: Taken together, we used a novel approach directly correlating gene expression values to time from transplant to overt leukemia (TTL) identifying the apoptosis regulator XAF1 to be associated with poor outcome of patients. Small XIAP-inhibiting molecules can be used to substitute the lacking inhibitory effect of down-regulated XAF1 in these poor responding pediatric ALL patients.

No significant financial relationships to disclose.

The inducible cyclic adenosine 3’,5’-monophosphate early repressor (ICER) enhances drug sensitivity in acute myeloid leukemia

e22045

Background: The Inducible Cyclic Adenosine 3’,5’-monophosphate early repressor (ICER) is a transcription factor that principally counteracts the cAMP response element binding protein (CREB) activity. CREB was previously demonstrated to be overexpressed in acute leukemia, whereas ICER was found rapidly degradated being unable to control gene transcription. ICER exogenous expression was demonstrated to repress CREB targets preventing leukemia progression. We hypothesized that ICER restoration deserves a special consideration for playing a role in CREB oncogenic feature and in modeling leukemic cell phenotype. Methods: We constructed an expression vector for ICER and induced its exogenous expression in HL60 cells (HL60+ICER). We monitored transcription and translation of a series of genes involved in different pathways by quantitative gene expression and western blot analysis. We investigate ICER's role in cell death after treatment with chemotherapic drugs. Results: We revealed that ICER was able to control gene expression in leukemia, principally of genes involved in cell death and survival. In particular, we focused on DUSP1 and DUSP4 phosphatases which were found significantly repressed. HL60+ICER after being treated with drugs increased apoptosis. Cell cycle analyses revealed a block in G2 phase, a lowered cell proliferation and clonogenic potential with respect to HL60 treated at the same conditions. DUSPs downstream targets (IL6, RB, RAS) were lowered expressed and p38 constitutively phosphorylated confirming their role in mediating cellular stress. ICER driven apoptosis was found to be caspases mediated. An enhanced activity of p38 was observed in treated HL60+ICER, and by the use of specific p38 inhibitors apoptosis decreased. Other possible apoptotic pathways (AKT, ERK, JNK) were excluded because found severely disrupted. Conclusions: Finally, we described an enhanced sensibility to drugs in HL60 induced by ICER exogenous expression and that p38 stress signaling pathway is the direct target of this phenomenon. The ability of ICER to modify leukemic cells phenotype respect to chemotherapeutic treatment gave an important information for targets and therapeutic possibilities.

No significant financial relationships to disclose.

Minimal residual disease-directed risk stratification using real-time quantitative PCR analysis of immunoglobulin and T-cell receptor gene rearrangements in the international multicenter trial AIEOP-BFM ALL 2000 for childhood acute lymphoblastic leukemia

Detection of minimal residual disease (MRD) is the most sensitive method to evaluate treatment response and one of the strongest predictors of outcome in childhood acute lymphoblastic leukemia (ALL). The 10-year update on the I-BFM-SG MRD study 91 demonstrates stable results (event-free survival), that is, standard risk group (MRD-SR) 93%, intermediate risk group (MRD-IR) 74%, and high risk group (MRD-HR) 16%. In multicenter trial AIEOP-BFM ALL 2000, patients were stratified by MRD detection using quantitative PCR after induction (TP1) and consolidation treatment (TP2). From 1 July 2000 to 31 October 2004, PCR target identification was performed in 3341 patients: 2365 (71%) patients had two or more sensitive targets (< or =10(-4)), 671 (20%) patients revealed only one sensitive target, 217 (6%) patients had targets with lower sensitivity, and 88 (3%) patients had no targets. MRD-based risk group assignment was feasible in 2594 (78%) patients: 40% were classified as MRD-SR (two sensitive targets, MRD negativity at both time points), 8% as MRD-HR (MRD > or =10(-3) at TP2), and 52% as MRD-IR. The remaining 823 patients were stratified according to clinical risk features: HR (n=108) and IR (n=715). In conclusion, MRD-PCR-based stratification using stringent criteria is feasible in almost 80% of patients in an international multicenter trial.

Microsurgical treatment of injury to peripheral nerves in upper and lower limbs: a critical review of the last 8 years

Nerve injuries to the upper and inferior limbs represent a common event due both to home and working accidents. Minor traumas can lead to severe disabilities if a wrong treatment is carried out. From 1997 to 2005, 920 patients were observed with a total of 1,200 major or minor nerves injuries operated. In 852 cases acute lesions treated. In 68 patients we reviewed old injuries. In 707 patients direct nerve suture and in 145 patients nerve grafts were carried out. One to 8 years follow up observed. Different protocols were adopted according to the injury: simple cut, complex lesion or surgical revision. Results were evaluated during the follow up period with different models: motor evaluation in six levels (BMRC), sensitive evaluation in five levels (HIGHET), and global evaluation with four grades (from the worst to the best result). Nerve healing is a complex biological phenomenon influenced by many parameters related both to the patient characteristics and nerve lesion. Functional and esthetical outcomes vary also according to: age, cultural and economic condition, health status, and smoking. Post operative rehabilitation is mandatory to obtain an acceptable functional result. Nerve injuries to the upper and inferior limbs represent a challenge for the microsurgeon. Ultimate success in nerve surgery is judged by functional as well as cosmetic parameters. Only patients with the appropriate indication should be operated and always by a skilled surgeon.