Health-related quality of life of survivors of childhood acute lymphoblastic leukemia: a systematic review.

PURPOSE: Acute lymphoblastic leukemia (ALL) survivors are the largest group of childhood cancer survivors; however, their risk for late effects is high. Cancer-related late effects have the potential to compromise health-related quality of life (HRQL) long into survivorship. None of the reviews so far have focused on ALL solely, but described HRQL for all childhood cancers. We aimed to identify ALL survivors at risk for poor HRQL and identify possible risk factors. METHOD: Following PRISMA guidelines, we performed a systematic review, searching published literature in Pubmed, PsycInfo, Embase, and the Cochrane database including all publications up to December 16, 2016. Two independent reviewers (JV and ER) screened eligible articles and assessed article quality. RESULTS: We found 31 studies representing 4356 survivors and 901 proxies. Thirteen studies found worse, eight found no difference, and three better, overall HRQL scores compared with healthy controls or norms. ALL survivors typically had better overall HRQL scores than survivors of other childhood cancers. Clinical variables (e.g., treatment received) were not consistently associated with HRQL; however, experiencing worse late effects was associated with lower HRQL. Survivor and parent socio-demographic factors and psychological factors such as resilience and depression were also associated with HRQL. CONCLUSION: ALL survivors appeared to have worse or equivalent HRQL compared with controls, but better HRQL than survivors of other cancer types. However, studies reported a wide variability in HRQL and potential risk factors for poor HRQL. Measuring ALL survivors' HRQL longitudinally and comprehensively assessing potential risk factors might identify future avenues to intervene early.

Health-related quality of life of children on treatment for acute lymphoblastic leukemia: A systematic review.

Children with acute lymphoblastic leukemia (ALL) undergo intense anticancer treatment. We systematically reviewed 22 studies evaluating 2,073 ALL patients' health-related quality of life (HRQL) and its clinical/demographic correlates during treatment. Overall HRQL was significantly reduced on treatment. Despite HRQL improvements over time, longitudinal studies reported a proportion of children continued to experience reduced HRQL after treatment completion. We found inconsistent associations between clinical/demographic factors and HRQL outcomes. Tentative evidence emerged for worse HRQL being associated with intensive phases of chemotherapy, corticosteroid therapy, experiencing greater toxicity, older age, and female sex. Longitudinal studies are needed to identify children at-risk of reduced HRQL.

Understanding the school experiences of children and adolescents with serious chronic illness: a systematic meta-review.

BACKGROUND: Serious chronic illness can have a detrimental effect on school attendance, participation and engagement, leaving affected students at risk of failing to meet their developmental potential. An improved understanding of factors that help to explain or mitigate this risk can help educators and health professionals deliver the most effective support. This meta-review critiqued the available evidence examining the link between six chronic illnesses (asthma, cancer, chronic kidney diseases, heart diseases, cystic fibrosis and gastrointestinal diseases) and children's and adolescents' school experiences and outcomes, as well as investigating the medical, school, psychosocial and sociodemographic factors that are linked to poorer or better school outcomes. METHODS: We searched CINAHL, Cochrane Database, EMBASE, ERIC, MEDLINE, ProQuest Theses and Dissertations, and PsycINFO (2000-2015). Systematic and narrative reviews, and meta-analyses, of original studies examining students' subjective school experiences and objective school outcomes were eligible. We used the Preferred Reporting Items for Systematic Reviews and Meta-analyses criteria to critically appraise all systematic reviews. The Grading of Recommendations Assessment, Development, and Evaluation system guided our recommendations for practice and research. RESULTS: Eighteen reviews of 172 studies including more than 40 000 students were eligible. Therefore, we chose to conduct a meta-review to provide an overview of the literature on the relationship between chronic illness and school experiences and outcomes. We also explored the associated medical, school, psychosocial and sociodemographic factors affecting the relationship between illness and school experiences and outcomes. CONCLUSION: Students with chronic illness demonstrate mixed school experiences and outcomes that are often worse than students without chronic illness. Modifiable factors, such as students' engagement with school, may be novel yet appropriate targets of educational support to ensure that these students reach their full schooling potential.

High throughput screening aids clinical decision-making in refractory acute myeloid leukaemia.

BACKGROUND: Despite advances in therapeutics for adverse-risk acute myeloid leukaemia (AML), overall survival remains poor, especially in refractory disease. Comprehensive tumour profiling and pre-clinical drug testing can identify effective personalised therapies. CASE: We describe a case of ETV6-MECOM fusion-positive refractory AML, where molecular analysis and in vitro high throughput drug screening identified a tolerable, novel targeted therapy and provided rationale for avoiding what could have been a toxic treatment regimen. Ruxolitinib combined with hydroxyurea led to disease control and enhanced quality-of-life in a patient unsuitable for intensified chemotherapy or allogeneic stem cell transplantation. CONCLUSION: This case report demonstrates the feasibility and role of combination pre-clinical high throughput screening to aid decision making in high-risk leukaemia. It also demonstrates the role a JAK1/2 inhibitor can have in the palliative setting in select patients with AML.

Reduced incidence of second solid tumors in survivors of childhood Hodgkin's lymphoma treated without radiation therapy.

BACKGROUND: We assessed the risk of developing second malignancies in children treated for Hodgkin's lymphoma (HL), the majority of whom received chemotherapy only. PATIENTS AND METHODS: The development of second malignancies in children with HL, treated between 1960 and 1999, was assessed. Results were obtained by both chart review and linkage with a centralized cancer registry. Tumor incidence was compared for patients treated with and without radiotherapy (RT) and with the general population. Risk factors for developing second tumors were assessed by multivariate analysis. RESULTS: Of 142 childhood HL patients, 63 had received RT and 79 had not. Overall survival was similar for both groups. Fourteen patients developed second solid tumors, 12 who had received RT and 2 treated with chemotherapy only (P <0.001), with a 30-year cumulative incidence of 24.7% [95% confidence interval (CI) 7.27-47.4] and 5.8% (95% CI 0-58.9), respectively (P = 0.01). The standardized incidence ratio for second solid tumors was 236 (95% CI 112.2-359.0) versus 43.6 (95% CI 0-103.9), respectively. Multivariate analysis showed treatment with RT was the only significant risks factor for developing second solid tumors. CONCLUSIONS: Children with HL without RT have a substantially lower incidence of second tumors than those treated with RT.

HLA-G polymorphisms, genetic susceptibility, and clinical outcome in childhood neuroblastoma.

Neuroblastoma is the most common solid tumor in children less than 5 years of age. The early onset of neuroblastoma suggests that genes involved in fetal development and pregnancy may have a putative role in the etiology of neuroblastoma. The human leukocyte antigen subtype G (HLA-G) molecule plays an important role in immune response regulation and appears to regulate immune tolerance during early pregnancy as well as tumor immunosurveillance. Elevated levels of soluble HLA-G (sHLA-G) have been detected in a number of malignancies including serum samples from neuroblastoma and have been reported to be predictive of tumor relapse in neuroblastoma. In light of previous investigations suggesting that single nucleotide polymorphisms in the HLA-G gene may impact on protein expression levels and isoform production, we examined the influence of HLA-G polymorphisms on the susceptibility and clinical outcome of neuroblastoma in 163 neuroblastoma patients and 404 healthy controls. The distribution of HLA-G polymorphisms, alleles, or allelic groups did not differ between children diagnosed with neuroblastoma and healthy controls. Our analyses did not detect an association between common HLA-G polymorphisms and clinical outcome in patients treated for neuroblastoma.

Experimental constraints on left-right symmetric models from muon decay.

The TWIST Collaboration has completed a new measurement of the energy-angle spectrum of positrons from the decay of highly polarized muons. A simultaneous measurement of the muon decay parameters ρ, δ, and P(µ)(π)ξ tests the standard model in a purely leptonic process and provides improved limits for relevant extensions to the standard model. Specifically, for the generalized left-right symmetric model |(g(R)/g(L))ζ|<0.020 and (g(L)/g(R))m(2)>578 GeV/c(2), both 90% C.L.

ATP7A is a novel target of retinoic acid receptor beta2 in neuroblastoma cells.

Increased retinoic acid receptor beta (RARbeta(2)) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RARbeta(2) expression is a common feature of many human cancers, suggesting that RARbeta(2) may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RARbeta(2) expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RARbeta(2) protein alone was sufficient for the growth inhibitory effects of RARbeta(2) on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RARbeta(2). The ectopic overexpression of the RARbeta(2) ABC domain was sufficient to induce ATP7A expression, whereas, RARbeta(2) siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor beta and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism.

Risk factors for symptomatic venous thromboembolism during therapy for childhood acute lymphoblastic leukemia.

BACKGROUND: Symptomatic venous thromboembolism (VTE) is an unpredictable and life-threatening toxicity, which occurs early in childhood acute lymphoblastic leukemia (ALL) therapy. Approximately 5% of children will experience VTE which is treated with anticoagulation. Asparaginase and corticosteroids are etiologic factors for VTE, however other clinical factors may modify this risk. PROCEDURE: We sought to i) assess published pre-treatment VTE risk factors ii) identify early clinical factors that were associated with VTE and iii) determine whether single nucleotide polymorphisms (SNPs) associated with VTE in non-cancer patients contributed to VTE in children with ALL. We performed a detailed, retrospective analysis of 1021 ALL patients treated between 1998 and 2013. Individual patient records were reviewed to ascertain VTE incidence and document treatment-related clinical variables. RESULTS: The incidence of VTE was 5.1%. Extremes of weight at diagnosis (<5th or >95th centile) was an independent risk factor in multivariable analysis, when added to published risk factors of age ≥10 years and mediastinal mass. When factors during induction/consolidation were considered separately: bacteremia, elevated serum gamma-glutamyl transferase and bilirubin were associated with VTE occurrence. None of the SNPs associated with VTE in non-cancer populations were significantly associated with VTE in our cohort. CONCLUSION: We found two known risk factors (age ≥ 10 years and mediastinal mass) in a large cohort of children treated for ALL and identified other factors associated with VTE such as weight extremes at diagnosis, bacteremia, and abnormal liver function which warrant further study. These VTE risk factors may form the basis of future thromboprophylaxis trials.

The Avatar Acceptability Study: Survivor, Parent and Community Willingness to Use Patient-Derived Xenografts to Personalize Cancer Care.

BACKGROUND: Using patient-derived xenografts (PDXs) to assess chemosensitivity to anti-cancer agents in real-time may improve cancer care by enabling individualized clinical decision-making. However, it is unknown whether this new approach will be met with acceptance by patients, family and community. METHODS: We used a cross-sectional structured survey to investigate PDX acceptability with 1550 individuals across Australia and New Zealand (648 survivors of adult and childhood cancer, versus 650 community comparisons; and 48 parents of childhood cancer survivors versus 204 community parents). We identified factors influencing willingness-to-use PDXs, willingness-to-pay, maximum acceptable wait-time, and maximum acceptable number of mice used per patient. FINDINGS: PDXs were highly acceptable: >80% of those affected by cancer felt the potential advantages of PDXs outweighed the disadvantages (community participants: 68%). Survivors' and survivors' parents' most highly endorsed advantage was 'increased chance of survival'. 'Harm to animals' was the least endorsed disadvantage for all groups. Cancer survivors were more willing to use PDXs than community comparisons [p < ·001]. Survivors and survivors' parents were willing to pay more [p < ·001; p = ∙004 respectively], wait longer for results [p = ·03; p = ∙01], and use more mice [p = ·01; p < ∙001] than community comparisons. Male survivors found PDXs more acceptable [p = ·01] and were willing to pay more [p < ·001] than female survivors. Survivors with higher incomes found PDXs more acceptable [p = ·002] and were willing to pay more [p < ·001] than survivors with lower incomes. Mothers found PDXs more acceptable [p = ·04] but were less willing to wait [p = ·02] than fathers. INTERPRETATION: We found significant attitudinal support for PDX-guided cancer care. Willingness-to-pay and maximum acceptable number of mice align well with likely future usage. Maximum acceptable wait-times were lower than is currently achievable, highlighting an important area for future patient education until technology has caught up.

Long-term outcomes in children with high-risk neuroblastoma treated with autologous stem cell transplantation.

We retrospectively analysed the outcomes of children transplanted for high-risk neuroblastoma (NB) at a single institution predominantly transplanted with total body irradiation and chemotherapy. The aims of this study were to determine the prognostic impact of clinical and biological features and to document long-term health outcomes. Forty patients were transplanted with a single unpurged autograft. Fourteen patients died from disease progression and two from late complications of treatment. Twenty-three patients are alive at a median of 4.6 years from diagnosis. Kaplan-Meier estimates of overall survival at 2, 5 and 10 years are 76+/-7.0, 60.2+/-8.4 and 54.7+/-9.3% following transplant. Response to induction therapy was significantly associated with survival (P<0.01). Long-term complications included growth (100%) and pubertal failure (83%), hearing impairment (73%), orthopaedic complications (63%), renal impairment (47%) and thyroid abnormalities (36%). Intrinsic and acquired resistance to chemotherapy remains the major obstacle to improving outcomes in high-risk NB. Although patients with chemo-sensitive disease are less likely to experience a relapse, substantial therapy-related toxicities result in poor long-term health outcomes for survivors.

Characterization of sarcoma cell lines from v-jun transgenic mice.

Wounding is a prerequisite for tumor formation in v-jun transgenic mice. The progression from wound to dermal sarcoma is a multistep process which, at some stage, results in an increase in transgene mRNA expression in tumor tissue. However, transgene expression in individual sarcoma cells stained for Jun protein cultures is heterogeneous. We cloned several cell lines from wound-related v-jun transgenic tumors to determine whether a relationship existed between the cellular growth properties and structure, expression, or function of the transgene. Cell lines with very high v-jun expression had a high cloning efficiency in soft agar and tumorigenicity in nude mice. However, for cell lines with an intermediate or low level of transgene expression there was no correlation between transgene expression and the transformed phenotype. There was also no correlation between transgene expression and individual cell line morphologies, growth rates, transgene genomic DNA copy number, or mRNA expression of jun-related genes. The tumor cell subclones (1-20.2, 3-24.3) with very low transgene expression, very poor cloning efficiency, and low tumorigenicity also showed reduced activator protein 1 DNA binding activity and had an increased expression of endogenous c-jun when compared to other tumor cell lines. Transfection of a v-jun expression vector into cell lines with poor cloning efficiency and low tumorigenicity enhanced both in vitro cloning and in vivo tumor formation. However, such overexpressed v-jun had no effect on NIH3T3 cells. Our studies show that expression of the v-jun transgene contributes to the transformed phenotype of tumor cell lines but that there are additional factors that determine growth properties in culture and in the animal.

Heterotransplantation of human lymphoid neoplasms using a nude mouse intraocular xenograft model.

There are few effective models for the study of human lymphoid neoplasms, including in vivo xenografts in immunocompromised animals. Exploiting the additional immune privilege of the anterior chamber of the nude mouse eye, a novel method of direct heterotransplantation of cells from childhood leukemias and lymphomas has been developed. The establishment and characterization of 18 lymphoid xenograft cell lines maintained in the nude mouse intraocular model are reported. Cell sources for heterotransplantation were specimens of bone marrow, peripheral blood, or lymphomatous masses obtained at either diagnosis or recurrence of disease in the patients. The 18 patients and resultant cell lines were grouped into four immunophenotypic categories: Category 1, B-lineage (pre-B and early pre-B), "common" acute lymphatic leukemias; Category 2, cell lines of similar immunophenotype derived from patients with unusual features; Category 3, B-cell neoplasms and cell lines; and Category 4, neoplasms and cell lines in part or totally of T-cell origin. With reference to these groupings, rates of ingraftment from clinical specimens varied according to immunophenotype and disease status: Category 1, 1 of 15 at diagnosis, 5 of 7 at relapse; Category 2, 1 of 1 at diagnosis, 2 of 2 at relapse; Category 3, 6 of 6 at diagnosis; and Category 4, 2 of 9 at diagnosis, 1 of 1 with persistent disease. Rearrangements of the genes for immunoglobulin heavy chain or kappa light chain and for beta subunit of the T-cell receptor gene were demonstrated according to immunophenotype, with the exception of one cell line which showed no rearrangements. Evidence of Epstein-Barr virus DNA was shown in only one cell line, of B-cell immunophenotype. Cytology, histopathology, and electron microscopy in representative patient and xenograft samples demonstrated correlations between the specimens of origin and cells or sections from ingrafted tumors in mice. It is concluded that the direct heterotransplantation of cells from childhood leukemias and lymphomas to the anterior chamber of the nude mouse eye provides a relevant and reproducible model for the maintenance and study of human lymphoid neoplasms.

Tumor necrosis factor alpha and interleukin 1 alpha induce anchorage independence in v-jun transgenic murine cells.

The oncogene jun encodes a transcription factor of the AP-1 family. In mice carrying viral jun (v-jun) as a transgene, wounding is a prerequisite for tumorigenesis, suggesting collaboration between the transgene and a wound-related event. To define possible candidates for this collaborative process, we examined the effect of several wound-related polypeptide growth factors on cells from transgenic mice. Tumor necrosis factor alpha and interleukin 1 alpha induce anchorage independence in embryo fibroblasts and tumor cell revertants from these mice. This effect was specific for the two cytokines and was restricted to cells from v-jun transgenic mice. Anchorage independence required the continued presence of the cytokines. Transfection of transgenic cells with a v-jun expression plasmid also induced anchorage independence and a tumorigenic phenotype in transgenic tumor cell revertants. However, there was no correlation between anchorage independence, expression of Jun, and AP-1 activity. These results suggest that while increased transgene expression can enhance the growth properties of v-jun transgenic cells, there exist other cytokine-dependent mechanisms that have a similar effect. Retinoic acid, dexamethasone, or forskolin inhibits induction of anchorage independence by tumor necrosis factor alpha, interleukin 1 alpha, and transfected v-jun. Although these agents affect both AP-1 transactivation potential and DNA binding in the transgenic cells, the changes are not correlated with the inhibition of growth.

Expression of the multidrug resistance-associated protein (MRP) gene correlates with amplification and overexpression of the N-myc oncogene in childhood neuroblastoma.

The MRP gene (Cole et al., Science (Washington DC), 258: 1650-1654, 1992) encodes a membrane-bound glycoprotein the expression of which correlates with non-P-glycoprotein-mediated multidrug resistance in a variety of cultured human cell lines. Using an RNA-polymerase chain reaction assay, expression of this gene was examined in the highly chemoresistant pediatric malignancy, neuroblastoma. MRP expression was observed in 5 human neuroblastoma cell lines and in all 25 primary neuroblastoma tumors of stage I through IVS. Tumors with amplification of the N-myc oncogene were found to have significantly higher MRP expression that those with no amplification (P = 0.0016). Expression of the MRP gene in the tumor specimens was highly correlated with expression of the N-myc gene (P = 0.0009), while expression of the MDR1 gene, encoding P-glycoprotein, was not related to expression of either the N-myc or MRP genes. Decreased expression of the N-myc oncogene in neuroblastoma cell lines SH-SY5Y and BE(2)-C, following treatment with retinoic acid, was paralleled by down-regulation of MRP gene expression, contrasting with increased expression of the MDR1 gene. Expression of the MRP gene is thus common in both primary neuroblastoma tumors and cultured cell lines, and correlates with amplification and overexpression of the N-myc oncogene, which is central to the malignant phenotype of this disease.

Expression of multiple endocrine neoplasia 2B RET in neuroblastoma cells alters cell adhesion in vitro, enhances metastatic behavior in vivo, and activates Jun kinase.

Point mutations, deletions, and recombinations of the RET proto-oncogene are associated with several inherited human diseases of neural crest-derived cells: Hirschsprung's disease, familial medullary thyroid carcinoma, and the multiple endocrine neoplasia (MEN) syndromes, types 2A and 2B. RET expression is restricted to normal and malignant cells of neural crest origin, such as human neuroblastoma cells. To better understand the role of the activated RET oncogene in neural crest cells, we transfected two adherent human neuroblastoma tumor cell lines with oncogenic MEN2 mutant RET cDNAs. Transfectant clones from both cell lines overexpressing MEN2B RET demonstrated a marked increase in the cell fraction growing in suspension. Both control and MEN2B cells formed tumors at the site of injection in all cases. However, mice injected with MEN2B cells developed lung metastases at a much higher frequency than control mice. Only RET protein derived from MEN2A transfectant cells had increased autokinase activity, whereas MEN2B transfectant cells demonstrated selective activation of the mitogen-activated protein kinase, Jun kinase-1 (Jnk1). These results indicate a biochemical signaling pathway that may link oncogenic RET with the metastatic process.

Favorable prognostic significance of high-level retinoic acid receptor beta expression in neuroblastoma mediated by effects on cell cycle regulation.

We have previously shown that ectopic overexpression of retinoic acid receptor (RAR) subtypes alpha, beta and gamma in human neuroblastoma cells had different effects on growth and retinoid sensitivity. Only overexpressed RAR beta induced profound growth inhibition in the absence of additional retinoid, and increased retinoid sensitivity. In this study, we measured mRNA expression levels of RAR alpha, beta, and gamma in 50 primary neuroblastoma tumor samples, and found a strong correlation between favorable patient prognosis and high-level RAR beta expression. Human neuroblastoma cells transfected with a vector expressing RAR beta demonstrated irreversible growth arrest following a 1 week exposure to all-transretinoic acid, whereas control cells continued to proliferate. In the absence of additional retinoid, RAR beta transfectants demonstrated a higher proportion of cells in the G0/G1 phase of the cell cycle, increased p21WAF1/CIP1 expression and specific binding to a retinoic acid response element. These were changes which we also observed in control neuroblastoma cells following retinoid treatment. Our data indicate that RAR beta is an important factor mediating the growth inhibitory effects of retinoids in neuroblastoma cells. The favorable effect of high-level RAR beta expression on prognosis in primary tumor tissue may occur through RAR beta effects on p21 expression and consequent G0/G1 cell cycle arrest.

Increased retinoic acid receptor gamma expression suppresses the malignant phenotype and alters the differentiation potential of human neuroblastoma cells.

Human neuroblastoma (NB) tumor cell lines treated in vitro with the retinoid, all-trans-retinoic acid (aRA), form neurites and undergo growth arrest. Retinoids exert their diverse morphologic effects through a signalling pathway which involves the nuclear retinoid receptors. Defective retinoic acid receptor (RAR) function contributes to the malignant phenotype of several human and experimental tumors. Considerable evidence from gene disruption studies now suggests that one of the RARs, RAR gamma, may directly mediate some retinoid effects on embryonic and malignant cells. We, firstly, examined primary NB tumor tissue for a correlation between endogenous RAR gamma expression and clinical stage of the tumor and secondly, the effects of exogenous over-expression of the RAR gamma gene on a human NB tumor cell line. RAR gamma mRNA expression in 32 primary NB tumor tissue samples were significantly higher in clinically localised tumors compared with advanced or disseminated tumors. The human NB tumor cell line, BE(2)-C, was stably transfected with a mammalian expression vector (pREP4) over-expressing the human RAR gamma cDNA. Two selected clones over-expressing RAR gamma (BE/G1 and 2) exhibited a reduced growth rate compared to control cells. Tumorigenicity was inhibited for BE/G1 cells and there was a delayed onset to tumor formation for BE/G2 cells. aRA caused growth inhibition but not neuritic differentiation of the BE/G clones, while 9-cis-retinoic acid caused both growth arrest and neuritic differentiation. Taken together these results suggest that reduced endogenous RAR gamma expression may contribute to the malignant phenotype of human NB. In NB cells the retinoid signalling pathway for neuritic differentiation may be distinct from that causing growth inhibition.

Altered expression of the MYCN oncogene modulates MRP gene expression and response to cytotoxic drugs in neuroblastoma cells.

We have recently shown a close correlation between expression of the Multidrug Resistance-associated Protein (MRP) gene and the MYCN oncogene and provided evidence that high MRP expression is a powerful independent predictor of poor outcome in neuroblastoma (Norris et al., New Engl. J. Med., 334, 231-238, 1996). The effect of MYCN down-regulation on MRP expression and response to cytotoxic drugs was investigated in NBL-S neuroblastoma cells transfected with MYCN antisense RNA constructs. Concomitant with MYCN down-regulation, the level of MRP expression was decreased in the NBAS-4 and NBAS-5 antisense transfectants. These cells demonstrated significantly increased sensitivity to the high affinity MRP substrates vincristine, doxorubicin, sodium arsenate and potassium antimony tartrate, but not to the poor MRP substrates, taxol or cisplatin. Similarly, transfection of full-length MYCN cDNA into SH-EP neuroblastoma cells resulted in increased MRP expression and significantly increased resistance specifically to MRP substrates. The results provide evidence for the MYCN oncogene influencing cytotoxic drug response via regulation of MRP gene expression. Our data also provide a link between the malignant and chemoresistant phenotypes of this childhood malignancy.

Prognostic significance of MYCN oncogene expression in childhood neuroblastoma.

PURPOSE: To assess the significance of MYCN gene expression as a prognostic factor in patients with neuroblastoma of various ages, and to determine whether it can predict for outcome independently of MYCN gene amplification. PATIENTS AND METHODS: The level of MYCN gene expression in 60 specimens of primary untreated neuroblastoma was determined by reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. RESULTS: High levels of MYCN gene expression were associated with advanced tumor stage (P=.0005), with the presence of MYCN gene amplification (P < .0001), but not with older age at diagnosis. Among patients who lacked MYCN gene amplification, the levels of MYCN gene expression were significantly greater in the tumors of infants compared with those of older children (P < .0005). High MYCN expression was strongly associated with reduced survival and event-free survival in the overall study population (P < .005), and also in the subset of patients aged older than 1 year at diagnosis (P < .001). In contrast, MYCN expression did not appear to be predictive of outcome in infants. After adjustment for the effect of MYCN amplification, high levels of MYCN expression retained significant prognostic value for poor survival (relative hazards, 30.3; P=.003) in children aged older than 12 months at diagnosis. CONCLUSION: High MYCN gene expression is strongly predictive of poor outcome in older children with neuroblastoma, but not in infants. The findings help explain the controversy in the literature about the prognostic value of MYCN gene expression and highlight the different biology of neuroblastoma that presents in infants and older children.