Project leaflet: Summary about the ARIMMORA project published in the BEMS (Bioelectromagnetics Society) Newsletter No. 223.
Publication: C. Vicente‐Dueñas, I. Romero‐Camarero, C. Cobaleda, and
I. Sánchez‐García, Function of oncogenes in cancer development: a changing paradigm. EMBO Journal 2013, 32: 1502–1513; doi: 10.1038/emboj.2013.97.
Tumour‐associated oncogenes induce unscheduled proliferation as well as genomic and chromosomal instability. According to current models, therapeutic strategies that block oncogene activity are likely to selectively target tumour cells. However, recent evidences have revealed that oncogenes are only essential for the proliferation of some specific tumour cell types, but not all. Indeed, the latest studies of the interactions between the oncogene and its target cell have shown that oncogenes contribute to cancer development not only by inducing proliferation but also by developmental reprogramming of the epigenome. This provides the first evidence that tumorigenesis can be initiated by stem cell reprogramming, and uncovers a new role for oncogenes in the origin of cancer. Here we analyse these evidences and propose an updated model of oncogene function that can explain the full range of genotype–phenotype associations found in human cancer. Finally, we discuss how this vision opens new avenues for developing novel anti‐cancer interventions.
Publication: I. Liorni, M. Parazzini,S. Fiocchi, M. Douglas, M. Capstick, M.-C. Gosselin, N. Kuster, and P. Ravazzani, Dosimetric Study of Fetal Exposure to Uniform Magnetic Fields at 50 Hz. Bioelectromagnetics 2014, 35: 580–597; doi: 10.1002/bem.21878.
Numerical modeling was used to analyze the exposure of fetuses at three different gestational ages (GA) to uniform magnetic fields at 50 Hz power line frequencies with different polarizations. Fetal whole-body and tissue-specific induced electric fields (E) and current densities (J) were analyzed as a function of both magnetic field polarization and GA. Particular emphasis was placed on choosing the tissue parameters used in the models, and a full survey of the relevant literature was performed. Induced field variations due to changes in fetal position were analyzed by means of two new pregnant models. The uncertainty budget due to the grid resolutionwas calculated, and the compliance of the fetal exposure with the ICNIRP Guidelines was checked. A fetal exposure matrix at 50 Hz, which could be used to further investigate possible interaction mechanisms between ELF-MF and health risk, was built. In summary, the induced fields increase with GA, but are in compliance with the ICNIRP Guidelines and well below the permitted threshold limit. The E and J maxima were found in skin and fat tissues for all GA; fetal tissue-specific exposure is modified as a function of GA and field polarization. Changes in the position of the fetus in the womb significantly modifies the induced E in some fetal tissues.
Publication: J. Hauer, A. Borkhardt, I. Sánchez-García, and C. Cobaleda, Genetically engineered mouse models of human B-cell precursor leukemias. Cell Cycle 2014, 13: 2836–2846; doi: 10.4161/15384101.2014.949137.
B-cell precursor acute lymphoblastic leukemias (pB-ALLs) are the most frequent type of malignancies of the childhood, and also affect an important proportion of adult patients. In spite of their apparent homogeneity, pB-ALL comprises a group of diseases very different both clinically and pathologically, and with very diverse outcomes as a consequence of their biology, and underlying molecular alterations. Their understanding (as a prerequisite for their cure) will require a sustained multidisciplinary effort from professionals coming from many different fields. Among all the available tools for pB-ALL research, the use of animal models stands, as of today, as the most powerful approach, not only for the understanding of the origin and evolution of the disease, but also for the development of new therapies. In this review we go over the most relevant (historically, technically or biologically) genetically engineered mouse models (GEMMs) of human pB-ALLs that have been generated over the last 20 years. Our final aim is to outline the most relevant guidelines that should be followed to generate an “ideal” animal model that could become a standard for the study of human pB-ALL leukemia, and which could be shared among research groups and drug
development companies in order to unify criteria for studies like drug testing, analysis of the influence of environmental risk factors, or studying the role of both low-penetrance mutations and cancer susceptibility alterations.
Publication: F. Abollo-Jiménez, E. Campos-Sánchez., A. Toboso-Navasa, C. Vicente‑Dueñas,
I. González‑Herrero, E. Alonso-Escudero, M. González, V. Segura, O. Blanco,
J. A. Martínez‑Climent, I. Sánchez-García, and C. Cobaleda, Lineage-specific function of Engrailed-2 in the progression of chronic myelogenous leukemia to T-cell blast crisis.
Cell Cycle 2014, 13: 1717–1726; doi: 10.4161/cc.28629.
In hematopoietic malignancies, oncogenic alterations interfere with cellular differentiation and lead to tumoral development. Identification of the proteins regulating differentiation is essential to understand how they are altered in malignancies. Chronic myelogenous leukemia (CML) is a biphasic disease initiated by an alteration taking place in hematopoietic stem cells. CML progresses to a blast crisis (BC) due to a secondary differentiation block in any of the hematopoietic lineages. However, the molecular mechanisms of CML evolution to T-cell BC remain unclear. Here, we have profiled the changes in DNA methylation patterns in human samples from BC-CML, in order to identify genes whose expression is epigenetically silenced during progression to T-cell lineage-specific BC. We have found that the CpG-island of the ENGRAILED-2 (EN2) gene becomes methylated in this progression. Afterwards, we demonstrate that En2 is expressed during T-cell development in mice and humans. Finally, we further show that genetic deletion of En2 in a CML transgenic mouse model induces a T-cell lineage BC that recapitulates human disease. These results identify En2 as a new regulator of T-cell differentiation whose disruption induces a malignant T-cell fate in CML progression, and validate the strategy used to identify new developmental regulators of hematopoiesis.
A. Martín-Lorenzo, J. Hauer, C. Vicente-Dueñas, F. Auer, I. González-Herrero, I. García-Ramírez, S. Ginzel, R. Thiele, S. N. Constantinescu, C. Bartenhagen, M. Dugas, M. Gombert, D. Schäfer, O. Blanco, A. Mayado, A. Orfao, D. Alonso-López, J. De Las Rivas, C. Cobaleda, M. B. García-Cenador, F. J. García-Criado, I. Sánchez-García, and A. Borkhardt, Infection Exposure Is a Causal Factor in B-cell Precursor Acute Lymphoblastic Leukemia as a Result of Pax5-Inherited Susceptibility. Cancer Discovery 2015, 5: 1328–1343; doi: 10.1158/2159-8290.CD-15-0892.
Earlier in the past century, infections were regarded as the most likely cause of childhood B-cell precursor acute lymphoblastic leukemia (pB-ALL). However, there is a lack of relevant biologic evidence supporting this hypothesis. We present in vivo genetic evidence mechanistically connecting inherited susceptibility to pB-ALL and postnatal infections by showing that pB-ALL was initiated in Pax5 heterozygous mice only when they were exposed to common pathogens. Strikingly, these murine pB-ALLs closely resemble the human disease. Tumor exome sequencing revealed activating somatic, nonsynonymous mutations of Jak3 as a second hit. Transplantation experiments and deep sequencing suggest that inactivating mutations in Pax5 promote leukemogenesis by creating an aberrant progenitor compartment that is susceptible to malignant transformation through accumulation of secondary Jak3 mutations. Thus, treatment of Pax5+/− leukemic cells with specific JAK1/3 inhibitors resulted in increased apoptosis. These results uncover the causal role of infection in pB-ALL development.
Significance: These results demonstrate that delayed infection exposure is a causal factor in pB-ALL. Therefore, these findings have critical implications for the understanding of the pathogenesis of leukemia and for the development of novel therapies for this disease.
Publication: G. Brown and I. Sánchez-García, Is lineage decision-making restricted during tumoral reprograming of haematopoietic stem cells? Oncotarget 2015, 6: 43326–43341; doi: 10.18632/oncotarget.6145.
Within the past years there have been substantial changes to our understanding of haematopoiesis and cells that initiate and sustain leukemia. Recent studies have revealed that developing haematopoietic stem and progenitor cells are much more heterogeneous and versatile than has been previously thought. This versatility includes cells using more than one route to a fate and cells having progressed some way towards a cell type retaining other lineage options as clandestine. These notions impact substantially on our understanding of the origin and nature of leukemia. An important question is whether leukemia stem cells are as versatile as their cell of origin as an abundance of cells belonging to a lineage is often a feature of overt leukemia. In this regard, we examine the coming of age of the “leukemia stem cell” theory and the notion that leukemia, like normal haematopoiesis, is a hierarchically organized tissue. We examine evidence to support the notion that whilst cells that initiate leukemia have multi-lineage potential, leukemia stem cells are reprogrammed by further oncogenic insults to restrict their lineage decision-making. Accordingly, evolution of a sub-clone of lineage-restricted malignant cells is a key feature of overt leukemia.
Publication: I. Liorni, M. Parazzini, S. Fiocchi, M. Douglas, M. Capstick, N. Kuster, and P. Ravazzani, Computational assessment of pregnant woman models exposed to uniform elf-magnetic fields: Compliance with the European current exposure regulations for the general public and occupational exposures at 50 Hz. Radiation Protection Dosimetry 2016, 172: 382–392; doi: 10.1093/rpd/ncv488.
The Recommendation 1999/529/EU and the Directive 2013/35/EU suggest limits for both general public and occupational exposures to extremely low-frequency magnetic fields, but without special limits for pregnant women. This study aimed to assess the compliance of pregnant women to the current regulations, when exposed to uniform MF at 50 Hz (100 μT for EU Recommendation and 1 and 6 mT for EU Directive). For general public, exposure of pregnant women and fetus always resulted in compliance with EU Recommendation. For occupational exposures, (1) Electric fields in pregnant women were in compliance with the Directive, with exposure variations due to fetal posture of <10 %, (2) electric fields in fetuses are lower than the occupational limits, with exposure variations due to fetal posture of >40 % in head tissues, (3) Electric fields in fetal CNS tissues of head are above the ICNIRP 2010 limits for general public at 1 mT (in 7 and 9 months gestational age) and at 6 mT (in all gestational ages).
I. Liorni, M. Parazzini, B. Struchen, S. Fiocchi, M. Röösli, and P. Ravazzani, Children’s Personal Exposure Measurements to Extremely Low Frequency Magnetic Fields in Italy. International Journal of Environmental Research and Public Health 2016, 13: 549; doi:10.3390/ijerph13060549
Extremely low frequency magnetic fields (ELF-MFs) exposure is still a topic of concern due to their possible impact on children’s health. Although epidemiological studies claimed an evidence of a possible association between ELF-MF above 0.4 μT and childhood leukemia, biological mechanisms able to support a causal relationship between ELF-MF and this disease were not found yet. To provide further knowledge about children’s ELF-MF exposure correlated to children’s daily activities, a measurement study was conducted in Milan (Italy). Eighty-six children were recruited, 52 of whom were specifically chosen with respect to the distance to power lines and built-in transformers to oversample potentially highly exposed children. Personal and bedroom measurements were performed for each child in two different seasons. The major outcomes of this study are: (1) median values over 24-h personal and bedroom measurements were <3 μT established by the Italian law as the quality target; (2) geometric mean values over 24-h bedroom measurements were mostly <0.4 μT; (3) seasonal variations did not significantly influence personal and bedroom measurements; (4) the highest average MF levels were mostly found at home during the day and outdoors; (5) no significant differences were found in the median and geometric mean values between personal and bedroom measurements, but were found in the arithmetic mean.
B. Struchen, I. Liorni, M. Parazzini, S. Gängler, P. Ravazzani, and M. Röösli, Analysis of personal and bedroom exposure to ELF-MFs in children in Italy and Switzerland. Journal of Exposure Science and Environmental Epidemiology 2016, 26, 586–596; doi:10.1038/jes.2015.80
Little is known about the real everyday exposure of children in Europe to extremely low-frequency magnetic fields (ELF-MFs). The aims of this study are to (i) assess personal ELF-MF exposure in children; (ii) to identify factors determining personal and bedroom ELF-MF exposure measurements in children; (iii) to evaluate the reproducibility of exposure summary measures; and (iv) to compare personal with bedroom measurements. In Switzerland and Italy, 172 children aged between 5 and 13 years were equipped with ELF-MF measurement devices (EMDEX II, measuring 40–800 Hz) during 24–72 h twice, in the warm and the cold season. In addition, 24-h measurements were taken in the bedroom of children. In our study, sample geometric mean ELF-MF exposure was 0.04 μT for personal and 0.05 μT for bedroom measurements. Living within 100 m of a highest voltage power line increased geometric mean personal exposure by a factor of 3.3, and bedroom measurements by a factor 6.8 compared to a control group. Repeated measurements within the same subject showed high reproducibility for the geometric mean (Spearman’s correlation 0.78 for personal and 0.86 for bedroom measurements) but less for the 95th and 99th percentile of the personal measurements (≤0.42). Spearman’s correlation between bedroom and personal exposure was 0.86 for the geometric mean but considerably lower for the 95th and 99th percentiles (≤0.60). Most previous studies on ELF-MF childhood leukaemia used mean bedroom exposure. Our study demonstrates that geometric mean bedroom measurements is well correlated with personal geometric mean exposure, and has high temporal reproducibility.
J. Schüz, C. Dasenbrock, P. Ravazzani, M. Röösli, P. Schär, P. L. Bounds, F. Erdmann, A. Borkhardt, C. Cobaleda, M. Fedrowitz, Y. Hamnerius, I. Sanchez-Garcia, R. Seger, K. Schmiegelow, G. Ziegelberger, M. Capstick, M. Manser, M. Müller, C. D. Schmid, D. Schürmann,B. Struchen, and N, Kuster6Extremely low-frequency magnetic fields and risk of childhood leukemia: A risk assessment by the ARIMMORA consortium. Bioelectromagnetics. 2016, 37: 183–189; doi: 10.1002/bem.21963.
Exposure to extremely low-frequency magnetic fields (ELF-MF) was evaluated in an International Agency for Research on Cancer (IARC) Monographs as “possibly carcinogenic to humans” in 2001, based on increased childhood leukemia risk observed in epidemiological studies. We conducted a hazard assessment using available scientific evidence published before March 2015, with inclusion of new research findings from the Advanced Research on Interaction Mechanisms of electroMagnetic exposures with Organisms for Risk Assessment (ARIMMORA) project. The IARC Monograph evaluation scheme was applied to hazard identification. In ARIMMORA for the first time, a transgenic mouse model was used to mimic the most common childhood leukemia: new pathogenic mechanisms were indicated, but more data are needed to draw definitive conclusions. Although experiments in different animal strains showed exposure-related decreases of CD8+ T-cells, a role in carcinogenesis must be further established. No direct damage of DNA by exposure was observed. Overall in the literature, there is limited evidence of carcinogenicity in humans and inadequate evidence of carcinogenicity in experimental animals, with only weak supporting evidence from mechanistic studies. New exposure data from ARIMMORA confirmed that if the association is nevertheless causal, up to 2% of childhood leukemias in Europe, as previously estimated, may be attributable to ELF-MF. In summary, ARIMMORA concludes that the relationship between ELF-MF and childhood leukemia remains consistent with possible carcinogenicity in humans. While this scientific uncertainty is dissatisfactory for science and public health, new mechanistic insight from ARIMMORA experiments points to future research that could provide a step-change in future assessments.
M. Manser, M. R. Abdul Sater, C. D. Schmid, F. Noreen, M. Murbach, N. Kuster, D. Schuermann, and P. Schär, ELF-MF exposure affects the robustness of epigenetic programming during granulopoiesis. Scientific Reports 7: 43345; doi: 10.1038/srep43345.
Extremely-low-frequency magnetic fields (ELF-MF) have been classified as "possibly carcinogenic" to humans on the grounds of an epidemiological association of ELF-MF exposure with an increased risk of childhood leukaemia. Yet, underlying mechanisms have remained obscure. Genome instability seems an unlikely reason as the energy transmitted by ELF-MF is too low to damage DNA and induce cancer-promoting mutations. ELF-MF, however, may perturb the epigenetic code of genomes, which is well-known to be sensitive to environmental conditions and generally deranged in cancers, including leukaemia. We examined the potential of ELF-MF to influence key epigenetic modifications in leukaemic Jurkat cells and in human CD34+ haematopoietic stem cells undergoing in vitro differentiation into the neutrophilic lineage. During granulopoiesis, sensitive genome-wide profiling of multiple replicate experiments did not reveal any statistically significant, ELF-MF-dependent alterations in the patterns of active (H3K4me2) and repressive (H3K27me3) histone marks nor in DNA methylation. However, ELF-MF exposure showed consistent effects on the reproducibility of these histone and DNA modification profiles (replicate variability), which appear to be of a stochastic nature but show preferences for the genomic context. The data indicate that ELF-MF exposure stabilizes active chromatin, particularly during the transition from a repressive to an active state during cell differentiation.
Summary of the first Periodic Report
Summary of the second Periodic Report
Summary of the third Periodic Report
Summary of the Final Report