Developmental genes and cancer in children

High Comorbidity of Pediatric Cancers in Patients with Birth Defects: Insights from Whole Genome Sequencing Analysis of Copy Number Variations

BACKGROUND

Patients with birth defects (BD) exhibit an elevated risk of cancer. We aimed to investigate the potential link between pediatric cancers and BDs, exploring the hypothesis of shared genetic defects contributing to the coexistence of these conditions.

METHODS

This study included 1454 probands with BDs (704 females and 750 males), including 619 (42.3%) with and 845 (57.7%) without co-occurrence of pediatric onset cancers. Whole genome sequencing (WGS) was done at 30X coverage through the Kids First/Gabriella Miller X01 Program.

RESULTS

8211 CNV loci were called from the 1454 unrelated individuals. 191 CNV loci classified as pathogenic/likely pathogenic (P/LP) were identified in 309 (21.3%) patients, with 124 (40.1%) of these patients having pediatric onset cancers. The most common group of CNVs are pathogenic deletions covering the region ChrX:52,863,011-55,652,521, seen in 162 patients including 17 males. Large recurrent P/LP duplications >5MB were detected in 33 patients.

CONCLUSIONS

This study revealed that P/LP CNVs were common in a large cohort of BD patients with high rate of pediatric cancers. We present a comprehensive spectrum of P/LP CNVs in patients with BDs and various cancers. Notably, deletions involving E2F target genes and genes implicated in mitotic spindle assembly and G2/M checkpoint were identified, potentially disrupting cell-cycle progression and providing mechanistic insights into the concurrent occurrence of BDs and cancers.

Clinical trio genome sequencing facilitates the interpretation of variants in cancer predisposition genes in paediatric tumour patients

The prevalence of pathogenic and likely pathogenic (P/LP) variants in genes associated with cancer predisposition syndromes (CPS) is estimated to be 8-18% for paediatric cancer patients. In more than half of the carriers, the family history is unsuspicious for CPS. Therefore, broad genetic testing could identify germline predisposition in additional children with cancer resulting in important implications for themselves and their families. We thus evaluated clinical trio genome sequencing (TGS) in a cohort of 72 paediatric patients with solid cancers other than retinoblastoma or CNS-tumours. The most prevalent cancer types were sarcoma (n = 26), neuroblastoma (n = 15), and nephroblastoma (n = 10). Overall, P/LP variants in CPS genes were identified in 18.1% of patients (13/72) and P/LP variants in autosomal-dominant CPS genes in 9.7% (7/72). Genetic evaluation would have been recommended for the majority of patients with P/LP variants according to the Jongmans criteria. Four patients (5.6%, 4/72) carried P/LP variants in autosomal-dominant genes known to be associated with their tumour type. With the immediate information on variant inheritance, TGS facilitated the identification of a de novo P/LP in NF1, a gonadosomatic mosaic in WT1 and two pathogenic variants in one patient (DICER1 and PALB2). TGS allows a more detailed characterization of structural variants with base-pair resolution of breakpoints which can be relevant for the interpretation of copy number variants. Altogether, TGS allows comprehensive identification of children with a CPS and supports the individualised clinical management of index patients and high-risk relatives.

Pediatric Tumors and Developmental Anomalies: A French Nationwide Cohort Study

OBJECTIVE

To assess the associations between congenital abnormalities and pediatric malignancies and evaluate the potential underlying molecular basis by collecting information on pediatric patients with cancer and congenital abnormalities.

STUDY DESIGN

Tumeur Et Développement is a national, prospective, and retrospective multicenter study recording data of children with cancer and congenital abnormalities. When feasible, blood and tumoral samples are collected for virtual biobanking.

RESULTS

From June 2013 to December 2019, 679 associations between pediatric cancers and congenital abnormalities were recorded. The most represented cancers were central nervous system tumors (n = 139; 20%), leukemia and myelodysplastic syndromes (n = 123; 18.1%), and renal tumors (n = 101; 15%). Congenital abnormalities were not related to any known genetic disorder in 66.5% of cases. In this group, the most common anomaly was intellectual disability (22.3%), followed by musculoskeletal (14.2%) and genitourinary anomalies (12.4%). Intellectual disability was mostly associated with hematologic malignancies. Embryonic tumors (neuroblastoma, Wilms tumor, and rhabdomyosarcoma) were associated with consistent abnormalities, sometimes with a close anatomical neighborhood between the abnormality and the neoplasm.

CONCLUSIONS

In the first Tumeur Et Développement analysis, 3 major themes have been identified: (1) germline mutations with or without known cancer predisposition, (2) postzygotic events responsible for genomic mosaicism, (3) coincidental associations. New pathways involved in cancer development need to be investigated to improve our understanding of childhood cancers.

The Role of the miR-548au-3p/CA12 Axis in Tracheal Chondrogenesis in Congenital Pulmonary Airway Malformations

Background

Literature has identified differentially expressed miRNAs in congenital pulmonary airway malformation (CPAM). However, the functional role of these miRNAs in CPAM remains unclear.

Methods

We obtained diseased lung tissues as well as adjacent normal lung tissue from CPAM patients attending the centre. Hematoxylin and eosin (H&E) and Alcian blue staining were performed. Differentially expressed mRNA expression profile was CPAM tissue, and matched normal tissue specimens were examined by high-throughput RNA sequencing. CCK-8 assay, EdU staining, TUNEL staining, flow cytometry, and the Transwell assay were performed to investigate the effect of miR-548au-3p/CA12 axis on proliferation, apoptosis, and chondrogenic differentiation in rat tracheal chondrocytes. mRNA and protein expression levels were determined using reverse transcription-quantitative PCR and western blot analysis, respectively. The relationship between miR-548au-3p and CA12 was evaluated using the luciferase reporter assay.

Results

The expression level of miR-548au-3p was significantly increased in diseased tissues compared with normal adjacent tissues from patients with CPAM. Our results indicate that miR-548au-3p functions as a positive regulator in rat tracheal chondrocyte proliferation and chondrogenic differentiation. At molecular level, miR-548au-3p promoted N-cadherin, MMP13, and ADAMTS4 expressions and reduced E-cadherin, aggrecan, and Col2A1 expressions. CA12 has been previously reported as a predicted target of miR-548au-3p, and here, we show that overexpression of CA12 in rat tracheal chondrocyte mimics the effects of inhibition of miR-548au-3p. On the other hand, CA12 knockdown reversed the effects of miR-548au-3p on cell proliferation, apoptosis, and chondrogenic differentiation.

Conclusions

In conclusion, the miR-548au-3p/CA12 axis plays a role in the pathogenesis of CPAM and may lead to identification of new approaches for CPAM treatment.

Congenital Heart Disease and the Risk of Cancer: An Update on the Genetic Etiology, Radiation Exposure Damage, and Future Research Strategies

Epidemiological studies have shown an increased prevalence of cancer in patients with congenital heart disease (CHD) as compared with the general population. The underlying risk factors for the acquired cancer risk remain poorly understood, and shared genetic anomalies and cumulative radiation exposure from repeated imaging and catheterization procedures may be contributing factors. In the present review, we provide an update on the most recent literature regarding the associations between CHD and cancer, with a particular focus on genetic etiology and radiation exposure from medical procedures. The current evidence indicates that children with CHD may be a high-risk population, already having the first genetic “hit”, and, consequently, may have increased sensitivity to ionizing radiation from birth or earlier. Future research strategies integrating biological and molecular measures are also discussed in this article.

Soil, Hand, and Body Adherence Measures across Four Beach Areas: Potential Influence on Exposure to Oil Spill Chemicals

Skin adherence (SA) of soil affects exposure from soil contaminants through dermal routes via loading on the skin and through ingestion routes through hand to mouth activities. The objectives of this study were to evaluate the relationships between adherence versus child-specific and environmental factors. Two sets of soil-to-skin adherence were evaluated. The first was based on loading on hands following hand presses (Hand SA). The second was based on body rinses following one hour of play activities on the beach (Body SA). Results for 98-119 children conducted at four beach sites show that mean Hand SA was 35.7 mg/cm2 (std. dev. 41.8 mg/cm2), while Body SA based on full coverage was 6.8 mg/cm2 (std. dev. 4.8 mg/cm2). Statistically significant differences in Body SA were observed between male (8.1 mg/cm2) and female (5.8 mg/cm2) children (p < 0.05). No significant difference by sex was found for Hand SA. Other statistically different observations were that Hand SA (p < 0.05), but not Body SA, differed across the four beaches (p < 0.05). For Hand SA, this difference was associated soil size variability across the beaches. Hand and Body SA values measured during this study are recommended for use in risk assessments that evaluate beach exposures to oil spill chemicals for young children.

Maternal and perinatal characteristics, congenital malformations and the risk of wilms tumor: the ESTELLE study

PURPOSE

Wilms tumor (WT), or nephroblastoma, is an embryonic tumor that constitutes the most common renal tumor in children. Little is known about the etiology of WT. The aim of this study was to investigate whether maternal or perinatal characteristics were associated with the risk of WT.

METHODS

The ESTELLE study is a national-based case-control study that included 117 cases of WT and 1,100 controls younger than 11 years old. The cases were children diagnosed in France in 2010-2011 and the controls were frequency matched with cases by age and gender. The mothers of case and control children responded to a telephone questionnaire addressing sociodemographic and perinatal characteristics, childhood environment, and lifestyle. Unconditional logistic regression models adjusted on potential cofounders were used to estimate the odds ratios (OR) and their confidence intervals (95% CI).

RESULTS

High birth weight and the presence of congenital malformation were associated with WT (OR 1.9 [95% CI 1.0-3.7] and OR 2.5 [95% CI 1.1-5.8], respectively). No association with breastfeeding or folic acid supplementation was observed.

CONCLUSIONS

Although potential recall bias cannot be excluded, our findings reinforce the hypothesis that high birth weight and the presence of congenital malformation may be associated with an increased risk of WT. Further investigations are needed to further elucidate the possible role of maternal characteristics in the etiology of WT.

β-Carotene 15,15'-oxygenase inhibits cancer cell stemness and metastasis by regulating differentiation-related miRNAs in human neuroblastoma

Neuroblastoma (NB) is the most common pediatric malignancy and is considered to possess cancer stem cells (CSCs) properties which can drive tumor initiation and metastasis. β-carotene 15,15'-oxygenase (BCO1) is the main enzyme that catalyzes the first step in vitamin A biosynthesis from pro-vitamin A carotenoids. Retinoids (vitamin A) play a critical role in NB differentiation. However, the biological functions of BCO1 in NB remained to be elucidated. Here, we investigated the effects of BCO1 on NB CSCs with stably expressing BCO1 in NB cells. We show that BCO1 significantly suppressed self-renewal and markers of NB CSCs. Moreover, BCO1 inhibited the metastatic potential of NB cells and suppressed the enzymatic activity and expression of MMPs, as well as expression of HIF-1α and its downstream targets. In vivo, BCO1 reduced the metastatic incidence and volumes of metastatic tumors and downregulated the expression of CSCs markers, MMPs, and HIF-1α in tumor tissues of a mouse xenograft model. A possible mechanism underlying the anti-cancer activities of BCO1 is proposed based on miRNAs sequencing array data which suggests a role for BCO1 in regulating miRNAs associated with neuronal differentiation, cell-cell adhesion, and the Wnt signaling pathway. Thus, our results demonstrate new chemotherapeutic roles for BCO1 in malignant NB that mediate suppression of cancer stemness and metastasis.

Cancer gene mutations in congenital pulmonary airway malformation patients

Background

Newborns affected with congenital pulmonary airway malformations (CPAMs) may present with severe respiratory distress or remain asymptomatic. While surgical resection is the definitive treatment for symptomatic CPAMs, prophylactic elective surgery may be recommended for asymptomatic CPAMs owing to the risk of tumour development. However, the implementation of prophylactic surgery is quite controversial on the grounds that more evidence linking CPAMs and cancer is needed. The large gap in knowledge of CPAM pathogenesis results in uncertainties and controversies in disease management. As developmental genes control postnatal cell growth and contribute to cancer development, we hypothesised that CPAMs may be underlain by germline mutations in genes governing airways development.

Methods

Sequencing of the exome of 19 patients and their unaffected parents.

Results

A more than expected number of mutations in cancer genes (false discovery rate q-value <5.01×10⁻⁵) was observed. The co-occurrence, in the same patient, of damaging variants in genes encoding interacting proteins is intriguing, the most striking being thyroglobulin (TG) and its receptor, megalin (LRP2). Both genes are highly relevant in lung development and cancer.

Conclusions

The overall excess of mutations in cancer genes may account for the reported association of CPAMs with carcinomas and provide some evidence to argue for prophylactic surgery by some surgeons.

Congenital pulmonary airway malformation (CPAM) patients have more than expected numbers of damaging variants in genes involved in lung carcinoma; this may provide evidence for clinicians choosing to adopt prophylactic excision in CPAMhttp://ow.ly/h1AE30n4DIe

Consumption of water from ex-mining ponds in Klang Valley and Melaka, Malaysia: A health risk study

Evaluation of health risks due to heavy metals exposure via drinking water from ex-mining ponds in Klang Valley and Melaka has been conducted. Measurements of As, Cd, Pb, Mn, Fe, Na, Mg, Ca, and dissolved oxygen, pH, electrical conductivity, total dissolved solid, ammoniacal nitrogen, total suspended solid, biological oxygen demand were collected from 12 ex-mining ponds and 9 non-ex-mining lakes. Exploratory analysis identified As, Cd, and Pb as the most representative water quality parameters in the studied areas. The metal exposures were simulated using Monte Carlo methods and the associated health risks were estimated at 95th and 99th percentile. The results revealed that As was the major risk factor which might have originated from the previous mining activity. For Klang Valley, adults that ingested water from those ponds are at both non-carcinogenic and carcinogenic risks, while children are vulnerable to non-carcinogenic risk; for Melaka, only children are vulnerable to As complications. However, dermal exposure showed no potential health consequences on both adult and children groups.

Cell death-based treatment of childhood cancer

Any therapy that aims at eradicating a cancerous growth will have at its core a cell death-inducing component. Here we argue that paediatric oncology presents with its unique set of considerations and problems, which—while taking the lead from oncological research experiences obtained from the adult population—need to be clinically evaluated independently. This is particularly true when considering long-term side effects. Precision medicine offers a promising new approach in therapy, but given as a monotherapy and in a limited combination, as found in an apoptosis inducer/sensitiser combination, it will most likely lead to mutation escape of the target cell population and the emergence of resistance. However, using the increasing amount of the molecular data as the basis for a complex combination therapy combining several key components such as cell death-inducing agents, kinase inhibitors and BH3 mimetics, holds great promise.

Congenital neurodevelopmental anomalies in pediatric and young adult cancer

Congenital anomalies that are diagnosed in at least 120,000 US infants every year are the leading cause of infant death and contribute to disability and pediatric hospitalizations. Several large-scale epidemiologic studies have provided substantial evidence of an association between congenital anomalies and cancer risk in children, suggesting potential underlying cancer-predisposing conditions and the involvement of developmental genetic pathways. Electronic medical records from 1,107 pediatric, adolescent, and young adult oncology patients were reviewed. The observed number (O) of congenital anomalies among children with a specific pediatric cancer subtype was compared to the expected number (E) of anomalies based on the frequency of congenital anomalies in the entire study population. The O/E ratios were tested for significance using Fisher's exact test. The Kaplan-Meier method was used to compare overall and neurological malignancy survival rates following tumor diagnosis. Thirteen percent of patients had a congenital anomaly diagnosis prior to their cancer diagnosis. When stratified by congenital anomaly subtype, there was an excess of neurological anomalies among children with central nervous system tumors (O/E = 1.56, 95%CI 1.13-2.09). Male pediatric cancer patients were more likely than females to have a congenital anomaly, particularly those <5 years of age (O/E 1.35, 95%CI 0.97-1.82). Our study provides additional insight into the association between specific congenital anomaly types and pediatric cancer development. Moreover, it may help to inform the development of new screening policies and support hypothesis-driven research investigating mechanisms underlying tumor predisposition in children with congenital anomalies.

Ancient genes establish stress-induced mutation as a hallmark of cancer

Cancer is sometimes depicted as a reversion to single cell behavior in cells adapted to live in a multicellular assembly. If this is the case, one would expect that mutation in cancer disrupts functional mechanisms that suppress cell-level traits detrimental to multicellularity. Such mechanisms should have evolved with or after the emergence of multicellularity. This leads to two related, but distinct hypotheses: 1) Somatic mutations in cancer will occur in genes that are younger than the emergence of multicellularity (1000 million years [MY]); and 2) genes that are frequently mutated in cancer and whose mutations are functionally important for the emergence of the cancer phenotype evolved within the past 1000 million years, and thus would exhibit an age distribution that is skewed to younger genes. In order to investigate these hypotheses we estimated the evolutionary ages of all human genes and then studied the probability of mutation and their biological function in relation to their age and genomic location for both normal germline and cancer contexts. We observed that under a model of uniform random mutation across the genome, controlled for gene size, genes less than 500 MY were more frequently mutated in both cases. Paradoxically, causal genes, defined in the COSMIC Cancer Gene Census, were depleted in this age group. When we used functional enrichment analysis to explain this unexpected result we discovered that COSMIC genes with recessive disease phenotypes were enriched for DNA repair and cell cycle control. The non-mutated genes in these pathways are orthologous to those underlying stress-induced mutation in bacteria, which results in the clustering of single nucleotide variations. COSMIC genes were less common in regions where the probability of observing mutational clusters is high, although they are approximately 2-fold more likely to harbor mutational clusters compared to other human genes. Our results suggest this ancient mutational response to stress that evolved among prokaryotes was co-opted to maintain diversity in the germline and immune system, while the original phenotype is restored in cancer. Reversion to a stress-induced mutational response is a hallmark of cancer that allows for effectively searching “protected” genome space where genes causally implicated in cancer are located and underlies the high adaptive potential and concomitant therapeutic resistance that is characteristic of cancer.

Childhood cancer in children with congenital anomalies in Oklahoma, 1997 to 2009

BACKGROUND

Data-linkage studies have reported an association between congenital anomalies and childhood cancer. However, few studies have focused on the differences in the effect of congenital anomalies on cancer as a function of attained age. We aimed to examine associations between anomalies and childhood cancer as a function of attained age among children born in Oklahoma.

METHODS

Data were obtained from the Oklahoma State Department of Health from 1997 to 2009 (n = 591,235). We linked Vital Statistics records for singleton deliveries to the Oklahoma Birth Defects Registry and the Oklahoma Central Cancer Registry using name and birth date. To assess the relation between anomalies and childhood cancer, we used Cox regression analysis allowing for a nonproportional hazards for anomalies as a function of age.

RESULTS

There were 23,368 (4.0%) children with anomalies and 531 (0.1%) children with cancer. When considering 3-year age intervals, we detected an increased hazard of any childhood cancer in children with anomalies compared with those without anomalies before 1 year of age (hazard ratio, 14.1; 95% confidence interval, 8.3-23.7) and at 3 years of age (hazard ratio, 2.3; 95% confidence interval, 1.6-3.2). The increased hazard declined with increasing time since birth, with the effect diminished by 6 years of age.

CONCLUSION

Our results were consistent with previous studies indicating an increased rate of childhood cancer among children with anomalies at younger ages. Furthermore, our study added a methodological refinement of assessing the effect of anomalies as a function of attained age. Birth Defects Research (Part A) 106:633-642, 2016. © 2016 Wiley Periodicals, Inc.

Risk of cancer among children with birth defects: a novel approach

BACKGROUND

Associations between birth defects (BDs) and childhood cancers have been studied previously and have identified several specific birth defect-cancer associations. No studies have examined the risk after exclusion of known associations.

METHODS

We analyzed data from high-quality population-based registers of BDs and cancers for Western Australian births 1982 to 2007. The cohort comprised 641,036 babies still alive at 90 days. Two experts independently reviewed all 120 births with a BD and a cancer to determine whether the cancer was congenital, caused by the BD, known to be associated with the BD or otherwise. These categories were used in sensitivity analyses. Cox regression was used to estimate hazard ratios (HRs) for any cancer and specific cancers associated with any BD and specific BDs.

RESULTS

The HR for any cancer among children with any BD was 1.96 (95% confidence interval, 1.59-2.43). The HR for any cancer among children with a BD not known to be related to a cancer (n = 57) was 1.19 (95% confidence interval, 0.91-1.56). The HR for the latter association among children diagnosed with cancer before 5 years of age was 1.74 (95% confidence interval, 1.28-2.37).

CONCLUSION

This novel approach aimed to prevent inflated HRs arising from reverse causation, and allow identification of associations beyond those already well documented. Larger studies using this method are needed to explore currently undocumented associations between BDs and cancers.

Oncolytic virus as a cancer stem cell killer: progress and challenges

Oncolytic viruses (OVs), which were discovered more than one century ago, have been used in multiple clinical trials for cancer therapy. OVs specifically target cancer cells when sparing normal cells by exploiting biochemical differences between normal and tumor cells. Hence oncolytic virotherapy is more specific at targeting cancer cells compared with conventional anti-cancer therapy. Apart from the lack of specificity, conventional anti-cancer therapies also often witness relapse and incomplete cure of cancer. One hypothesis explaining this phenomenon is that a subpopulation of cancer cells, known as cancer stem cells (CSCs), are resistant to conventional therapies, possibly due to its self-renewal and differentiation abilities. With the discovery of CSCs, researchers have been trying to explain whether OVs are well suited to eliminate CSCs. Two explanations for postulating OVs as ideal candidates for cancer therapy have been proposed: first, OVs are not subject to the same mechanisms responsible for chemotherapy and radiation resistance; second, viruses could be harnessed to express therapeutic transgenes that specifically target the features unique to CSCs or the properties CSCs rely on for self-renewal and differentiation. Indeed, initial studies suggest that OVs could effectively target CSCs in multiple tumor types. The focus of this review is to highlight recent studies related to the application of OVs on targeting CSCs, based on which, the challenges and perspectives for further research in this field will also be discussed.

Finding novel molecular connections between developmental processes and disease

Identifying molecular connections between developmental processes and disease can lead to new hypotheses about health risks at all stages of life. Here we introduce a new approach to identifying significant connections between gene sets and disease genes, and apply it to several gene sets related to human development. To overcome the limits of incomplete and imperfect information linking genes to disease, we pool genes within disease subtrees in the MeSH taxonomy, and we demonstrate that such pooling improves the power and accuracy of our approach. Significance is assessed through permutation. We created a web-based visualization tool to facilitate multi-scale exploration of this large collection of significant connections (http://gda.cs.tufts.edu/development). High-level analysis of the results reveals expected connections between tissue-specific developmental processes and diseases linked to those tissues, and widespread connections to developmental disorders and cancers. Yet interesting new hypotheses may be derived from examining the unexpected connections. We highlight and discuss the implications of three such connections, linking dementia with bone development, polycystic ovary syndrome with cardiovascular development, and retinopathy of prematurity with lung development. Our results provide additional evidence that plays a key role in the early pathogenesis of polycystic ovary syndrome. Our evidence also suggests that the VEGF pathway and downstream NFKB signaling may explain the complex relationship between bronchopulmonary dysplasia and retinopathy of prematurity, and may form a bridge between two currently-competing hypotheses about the molecular origins of bronchopulmonary dysplasia. Further data exploration and similar queries about other gene sets may generate a variety of new information about the molecular relationships between additional diseases.

Understanding the roles that genes involved in normal human development can play in disease processes is an important part of predicting disease risk and designing novel treatment approaches. In this study, we have identified classes of disease that are associated with a surprisingly large number of genes involved in any of several tissue-specific developmental processes. To do so, we developed a novel approach whose strength comes from pooling genetic information across related diseases, overcoming problems ordinarily posed by limited information about individual gene-disease relationships. We demonstrate the method's efficacy both by examining its ability to highlight connections between gene sets and disease classes that are known to be related, and by demonstrating that the approach recovers expected broad classes of connections, such as those between heart development and cardiovascular disorders. However, by examining unexpected connections in this data set, we are able to develop new understanding of some surprising disease relationships, such as the one between dementia and osteoporosis. Such connections may lead to a better overall understanding of the role of development in lifelong health, as well as to the design of new methods to treat a range of diseases.

Neonatal tumours

Neonatal or perinatal tumours frequently relate to prenatal or developmental events and have a short exposure window which provides an opportunity to study tumours in a selective sensitive period of development. As a result, they display a number of host-specific features which include occasional spontaneous maturational changes with cells still responding to developmental influences. Neonatal tumours (NNT) are studied for a number of important reasons. Firstly, many of the benign tumours arising from soft tissue appear to result from disturbances in growth and development and some are associated with other congenital anomalies. Study of these aspects may open the door for investigation of genetic and epigenetic changes in genes controlling foetal development as well as environmental and drug effects during pregnancy. Secondly, the clinical behaviour of NNT differs from that of similar tumours occurring later in childhood. In addition, certain apparently malignant NNT can 'change course' in infancy leading to the maturation of apparently highly malignant tumours. Thirdly, NNT underline the genetic associations of most tumours but appear to differ in the effects of proto-oncogenes and other oncogenic factors. In this context, there are also connections between the foetal and neonatal period and some "adult" cancers. Fourthly, they appear to arise in a period in which minimal environmental interference has occurred, thus providing a unique potential window of opportunity to study the pathogenesis of tumour behaviour. This study will seek to review what is currently known in each of these areas of study as they apply to NNT. Further study of the provocative differences in tumour behaviour in neonates provides insights into the natural history of cancer in humans and promotes novel cancer therapies.

Targeting developmental pathways in children with cancer: what price success?

Much of current cancer research is aimed at exploiting cancers' molecular addictions through targeted therapeutics, with notable successes documented in clinical trials. By their nature, these agents have different side-effect profiles than conventional chemotherapy drugs. Although few targeted agents have attained regulatory approval for use in children, paediatric oncologists are gaining experience with these drugs, which can have unique short-term and long-term effects in developing children that are unrecognised in adults. This Review summarises the rationale for targeted therapy, challenges in paediatric drug development, unique side-effect profiles of targeted agents, limited data from children treated with targeted agents, and implications of current knowledge and gaps therein. The demonstrated and potential effects of targeted therapies on normal tissue development and function are discussed. Future clinical trial design should include carefully considered assessment of the developmental effects of targeted therapy, and informed supportive-care recommendations.

Pediatric glioma stem cells: biologic strategies for oncolytic HSV virotherapy

While glioblastoma multiforme (GBM) is the most common adult malignant brain tumor, GBMs in childhood represent less than 10% of pediatric malignant brain tumors and are phenotypically and molecularly distinct from adult GBMs. Similar to adult patients, outcomes for children with high-grade gliomas (HGGs) remain poor. Furthermore, the significant morbidity and mortality yielded by pediatric GBM is compounded by neurotoxicity for the developing brain caused by current therapies. Poor outcomes have been attributed to a subpopulation of chemotherapy and radiotherapy resistant cells, termed “glioma stem cells” (GSCs), “glioma progenitor cells,” or “glioma-initiating cells,” which have the ability to initiate and maintain the tumor and to repopulate the recurring tumor after conventional therapy. Future innovative therapies for pediatric HGG must be able to eradicate these therapy-resistant GSCs. Oncolytic herpes simplex viruses (oHSV), genetically engineered to be safe for normal cells and to express diverse foreign anti-tumor therapeutic genes, have been demonstrated in preclinical studies to infect and kill GSCs and tumor cells equally while sparing normal brain cells. In this review, we discuss the unique aspects of pediatric GSCs, including markers to identify them, the microenvironment they reside in, signaling pathways that regulate them, mechanisms of cellular resistance, and approaches to target GSCs, with a focus on the promising therapeutic, genetically engineered oHSV.

Are children with birth defects at higher risk of childhood cancers?

Birth defects may influence the risk of childhood cancer development through a variety of mechanisms. The rarity of both birth defects and childhood cancers makes it challenging to study these associations, particularly for the very rare instances of each. To address this limitation, the authors conducted a record linkage-based cohort study among Texas children born between 1996 and 2005. Birth defects in the cohort were identified through the Texas Birth Defects Registry, and children who developed cancer were identified by using record linkage with Texas Cancer Registry data. Over 3 million birth records were included; 115,686 subjects had birth defects, and there were 2,351 cancer cases. Overall, children with a birth defect had a 3-fold increased risk of developing cancer (incidence rate ratio (IRR) = 3.05, 95% confidence interval (CI): 2.65, 3.50), with germ cell tumors (IRR = 5.19, 95% CI: 2.67, 9.41), retinoblastomas (IRR = 2.34, 95% CI: 1.21, 4.16), soft-tissue sarcomas (IRR = 2.12, 95% CI: 1.09, 3.79), and leukemias (IRR = 1.39, 95% CI: 1.09, 1.75) having statistically significant elevated point estimates. All birth defect groups except for musculoskeletal had increased cancer incidence. Untangling the strong relation between birth defects and childhood cancers could lead to a better understanding of the genetic and environmental factors that affect both conditions.

Targeting pediatric cancer stem cells with oncolytic virotherapy

Cancer stem cells (CSCs), also termed "cancer-initiating cells" or "cancer progenitor cells," which have the ability to self-renew, proliferate, and maintain the neoplastic clone, have recently been discovered in a wide variety of pediatric tumors. These CSCs are thought to be responsible for tumorigenesis and tumor maintenance, aggressiveness, and recurrence due to inherent resistance to current treatment modalities such as chemotherapy and radiation. Oncolytic virotherapy offers a novel, targeted approach for eradicating pediatric CSCs using mechanisms of cell killing that differ from conventional therapies. Moreover, oncolytic viruses have the ability to target specific features of CSCs such as cell-surface proteins, transcription factors, and the CSC microenvironment. Through genetic engineering, a wide variety of foreign genes may be expressed by oncolytic viruses to augment the oncolytic effect. We review the current data regarding the ability of several types of oncolytic viruses (herpes simplex virus-1, adenovirus, reovirus, Seneca Valley virus, vaccinia virus, Newcastle disease virus, myxoma virus, vesicular stomatitis virus) to target and kill both CSCs and tumor cells in pediatric tumors. We highlight advantages and limitations of each virus and potential ways in which next-generation engineered viruses may target resilient CSCs.

Epigenetic mechanisms regulating neural development and pediatric brain tumor formation

Pediatric brain tumors are the leading cause of cancer-related death in children, and among them, embryonal tumors represent the largest group with an associated poor prognosis and long-term morbidity for survivors. The field of cancer epigenetics has emerged recently as an important area of investigation and causation of a variety of neoplasms, and is defined as alterations in gene expression without changes in DNA sequence. The best studied epigenetic modifications are DNA methylation, histone modifications, and RNA-based mechanisms. These modifications play an important role in normal development and differentiation but their dysregulation can lead to altered gene function and cancer. In this review the authors describe the mechanisms of normal epigenetic regulation, how they interplay in neuroembryogenesis, and how these can cause brain tumors in children when dysregulated. The potential use of epigenetic markers to design more effective treatment strategies for children with malignant brain tumors is also discussed.

Cancer Stem Cells and Pediatric Solid Tumors

Recently, a subpopulation of cells, termed tumor-initiating cells or tumor stem cells (TSC), has been identified in many different types of solid tumors. These TSC, which are typically more resistant to chemotherapy and radiation compared to other tumor cells, have properties similar to normal stem cells including multipotency and the ability to self-renew, proliferate, and maintain the neoplastic clone. Much of the research on TSC has focused on adult cancers. With considerable differences in tumor biology between adult and pediatric cancers, there may be significant differences in the presence, function and behavior of TSC in pediatric malignancies. We discuss what is currently known about pediatric solid TSC with specific focus on TSC markers, tumor microenvironment, signaling pathways, therapeutic resistance and potential future therapies to target pediatric TSC.

Holoprosencephaly and holoprosencephaly-like phenotypes: Review of facial and molecular findings in patients from a craniofacial hospital in Brazil

Here we report on the clinical and genetic data for a large sample of Brazilian patients studied at the Hospital de Reabilitação de Anomalas Craniofaciais-Universidade de São Paulo (HRAC-USP) who presented with either the classic holoprosencephaly or the holoprosencephaly-like (HPE-L) phenotype. The sample included patients without detected mutations in some HPE determinant genes such as SHH, GLI2, SIX3, TGIF, and PTCH, as well as the photographic documentation of the previously reported patients in our Center. The HPE-L phenotype has been also called of HPE "minor forms" or "microforms." The variable phenotype, the challenge of genetic counseling, and the similarities to patients with isolated cleft lip/palate are discussed.

Cancer stem cell genomics: the quest for early markers of malignant progression

Biologically distinct populations of neoplastic stem cells have been identified in a variety of human cancers, in which they are associated with the initial steps of tumorigenesis. The intrinsic properties of self-renewal, clonogenicity and multipotency, along with a longer half-life within the body, may render normal adult stem cells more prone to accumulate genetic mutations leading to neoplastic transformation, as predicted by the cancer stem cell hypothesis. Tumor formation is also associated with the pluripotency of embryonic stem cells and may be induced as a consequence of complete dedifferentiation of mature cells, as recently reported for induced pluripotent stem cells. The tumor-initiating cell phenotype may result from genetic alterations affecting the expression of critical genes regulating typical stem cell processes such as self-renewal and pluripotency, in addition to genes determining stem cell senescence or longevity. Detailed genome-wide analysis of cancer stem cells and respective normal counterparts will help elucidate the cellular and molecular nature of tumors, providing fundamental information about the initial steps toward malignant transformation. Devising ways of detecting such genetic and epigenetic alterations and cell populations displaying them would allow medical interventions at the early phases of cancer development, thereby improving the chances of favorable clinical outcomes.