The shortest isoform of dystrophin (Dp40) interacts with a group of presynaptic proteins to form a presumptive novel complex in the mouse brain

Duchenne muscular dystrophy (DMD) causes cognitive impairment in one third of the patients, although the underlying mechanisms remain to be elucidated. Recent studies showed that mutations in the distal part of the dystrophin gene correlate well with the cognitive impairment in DMD patients, which is attributed to Dp71. The study on the expression of the shortest isoform, Dp40, has not been possible due to the lack of an isoform specific antibody. Dp40 has the same promoter as that found in Dp71 and lacks the normal C-terminal end of Dp427. In the present study, we have raised polyclonal antibody against the N-terminal sequence common to short isoforms of dystrophin, including Dp40, and investigated the expression pattern of Dp40 in the mouse brain. Affinity chromatography with this antibody and the consecutive LC-MS/MS analysis on the interacting proteins revealed that Dp40 was abundantly expressed in synaptic vesicles and interacted with a group of presynaptic proteins, including syntaxin1A and SNAP25, which are involved in exocytosis of synaptic vesicles in neurons. We thus suggest that Dp40 may form a novel protein complex and play a crucial role in presynaptic function. Further studies on these aspects of Dp40 function might provide more insight into the molecular mechanisms of cognitive impairment found in patients with DMD.

A case of steroid-resistant nephrotic syndrome associated with systemic lupus erythematosus

We report on an 11-year-old girl who developed steroid-resistant nephrotic syndrome (NS) at the onset of systemic lupus erythematosus (SLE), and clinical and renal histological findings suggested that her NS would be associated with SLE-related podocytopathy. Although initial treatment with intravenous pulse methylprednisolone was ineffective, following treatment with cyclosporine and an angiotensin receptor blocker was effective for her nephrotic proteinuria. She had developed posterior reversible encephalopathy syndrome (PRES), and mycophenolate mofetil (MMF) was started instead of cyclosporine. At present, 45 months after the onset, she is in remission of both NS and SLE. This case indicates that NS associated with SLE-related podocytopathy should be included in the spectrum of glomerulopathy accompanying SLE, also in the pediatric population.

Experience of fluoroscopy-aided thoracoscopic resection of pulmonary nodule localised with Lipiodol in a child

We report the case of a 12-year-old boy with a huge liver tumour 20 cm in diameter with multiple lung metastases. Six months after systemic chemotherapy was initiated, all tumours had disappeared with the exception of the liver tumour and a tiny lung tumour 2.5 mm in diameter. Fluoroscopy-assisted thoracoscopic resection of the pulmonary nodule was performed to evaluate whether viable tumour tissue remained in the lung lesion. Before moving the patient to the operating room, the nodule was marked by Lipiodol under CT fluoroscopic guidance with the patient under local anaesthesia. This procedure allowed correct visualisation of the area that should be resected.

Sensitivity of malignant rhabdoid tumor cell lines to PD 0332991 is inversely correlated with p16 expression

Malignant rhabdoid tumor (MRT) is a rare and highly aggressive neoplasm of young children. MRT is characterized by inactivation of integrase interactor 1 (INI1). Cyclin-dependent kinase 4 (CDK4), which acts downstream of INI1, is required for the proliferation of MRT cells. Here we investigated the effects of PD 0332991 (PD), a potent inhibitor of CDK4, against five human MRT cell lines (MP-MRT-AN, KP-MRT-RY, G401, KP-MRT-NS, KP-MRT-YM). In all of the cell lines except KP-MRT-YM, PD inhibited cell proliferation >50%, (IC(50) values 0.01 to 0.6 μM) by WST-8 assay, and induced G1-phase cell cycle arrest, as shown by flow cytometry and BrdU incorporation assay. The sensitivity of the MRT cell lines to PD was inversely correlated with p16 expression (r=0.951). KP-MRT-YM cells overexpress p16 and were resistant to the growth inhibitory effect of PD. Small interfering RNA against p16 significantly increased the sensitivity of KP-MRT-YM cells to PD (p<0.05). These results suggest that p16 expression in MRT could be used to predict its sensitivity to PD. PD may be an attractive agent for patients with MRT whose tumors express low levels of p16.

Preoperative analysis of 11q loss using circulating tumor-released DNA in serum: a novel diagnostic tool for therapy stratification of neuroblastoma

Allelic deletion of the long arm of chromosome 11 (11q loss) is closely associated with the prognosis of neuroblastoma (NB). Here we examined 11q loss using tumor-released DNA fragments in the sera of 24 cases. The allelic intensity score of a panel of polymorphic markers in 11q23 in serum DNA was significantly different between the 11q loss-positive group and the11q loss-negative group. The 11q loss-positive and -negative groups did not overlap when a cut-off value of 0.5 was chosen for the allelic intensity score. Our serum-based 11q loss analysis could predict the allelic status of 11q in tumors.

Detection of MYCN DNA in the cerebrospinal fluid for diagnosing isolated central nervous system relapse in neuroblastoma

We present the case of a 1-year-old female with stage-4 neuroblastoma with MYCN amplification; she was treated with five chemotherapy courses, resulting in normalization of elevated serum levels of tumor markers. Complete remission was achieved after allogeneic hematopoietic stem-cell transplantation with reduced-intensity conditioning. Nine months later, however, the tumor relapsed in the central nervous system (CNS). The serum and cerebrospinal fluid (CSF) levels of the tumor markers were normal, but the MYCN copy number was high only in the CSF DNA, suggesting an isolated CNS recurrence. The MYCN copy number in the CSF DNA was reflective of response to treatment.

Abstract 5346: Dual role of PAX3-NCOA2 in tumorigenesis of rhabdomyosarcoma

Introduction: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and young adults, and can be classified into two major histological subtypes, embryonal RMS and alveolar RMS. Recently, two novel fusion genes, PAX3-NCOA1 and PAX3-NCOA2, were identified in the embryonal and alveolar subtypes. We previously analyzed the complex chromosomal translocation in one case with embryonal RMS by means of spectral karyotyping (SKY) and identified a translocation involving chromosome band 2q35, which is the locus of the PAX3 gene (Hosoi H, Kakazu N, et al. Cancer Genetics and Cytogenetics 189 (2009) 98-104). The patient is alive and in remission at nine years after treatment. We later identified a PAX3 partner gene as NCOA2 using fluorescence in situ hybridization (FISH) and cDNA sequence analysis. Because the role of PAX3-NCOA2 in rhabdomyosarcoma tumorigenesis is unknown, we investigated the biological function of PAX3-NCOA2 in this study.

Methods: Mouse myoblast C2C12 cells and human embryonic kidney HEK293 cells were cultured in DMEM containing 10% fetal bovine serum. HEK293 cells were transfected with GFP-PAX3-NCOA2 expression vector and the fusion protein was localized by confocal microscopy. C2C12 cell lines expressing wild type PAX3, PAX3-FOXO1, PAX3-NCOA2 and a C-terminal activation domain deletion mutant of PAX3 were established using a murine stem cell virus (MSCV) retrovirus expression system. Anchorage-independent growth was assessed using soft agar colony formation. Myosin Heavy Chain (MHC), a marker of fully differentiated myocytes, was identified immunohistochemically. Myogenic differentiation was induced by switching the medium to DMEM containing 2% horse serum.

Results and Discussion: In transfected HEK293 cells, GFP-PAX3-NCOA2 was observed in the nucleus, consistent with the hypothesis that PAX3-NCOA2 is involved in transcriptional regulation. Expression of PAX3-NCOA2 protein promoted anchorage-independent growth in C2C12 myoblasts. The number of colonies of the PAX3-NCOA2 stable cell line was half the number of colonies of the PAX3-FOXO1 stable cell line. Negligible colony formation was observed in wild-type PAX3 and PAX3 deletion mutant stable cell lines. Expression of PAX3-NCOA2, wild-type PAX3 and PAX3-FOXO1 each blocked the fusion of myoblasts to myotubes in differentiation medium. MHC was not detected in any of the PAX3-NCOA2, wild-type PAX3 or PAX3-FOXO1 stable cell lines. The PAX3-NCOA2 and PAX3-FOXO1 stable cell lines had the comparable phenotype. However, the finding that the PAX3-NCOA2 stable cell line produced fewer colonies than the PAX3-FOXO1 stable cell line may indicate that RMS with PAX3-NCOA2 fusion gene has a less aggressive phenotype and a better prognosis.

Conclusions: The PAX3-NCOA2 fusion gene promoted anchorage-independent growth and inhibited myogenic differentiation in mouse myoblasts. These data suggest that PAX3-NCOA2 has a dual role in the tumorigenesis of RMS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5346. doi:10.1158/1538-7445.AM2011-5346

Development of corpus callosum in preterm infants is affected by the prematurity: in vivo assessment of diffusion tensor imaging at term-equivalent age

Callosal injury in preterm infants is a key factor affecting neurodevelopmental outcome. We investigated the characteristics of corpus callosum (CC) in preterm infants without apparent white matter lesions. We studied 58 preterm infants divided into three groups of 23-25, 26-29, and 30-33 wk GA. Diffusion tensor imaging (DTI) was obtained at term-equivalent age. The CC was parcellated into the genu, body, isthmus, and splenium. We measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of each CC subdivision using tractography and manual region of interest analysis. The cross-sectional areas were also measured. At the isthmus and splenium in the 23-25 GA group, the FA was significantly lower and the size was also significantly reduced. Furthermore, the FA and cross-sectional areas in the posterior CC decreased linearly with decreasing GA. There were no differences in FA and cross-sectional areas in other CC subdivisions, and no differences in ADC in any CC subdivisions, among the GA groups. We demonstrated that preterm infants without apparent white matter lesions affect development of the posterior CC depending on the degree of prematurity.

[Recurrence of transient splenial lesions in a child with "benign convulsions with gastroenteritis"]

We report a 2-year-old girl who demonstrated "benign convulsions with gastroenteritis (CwG)" with transient splenial lesions twice during the winter. The first episode was associated with noro-virus and the second with rota-virus. During each episode, seizures occurred in clusters without clinical signs of dehydration, hypoglycemia, electrolyte derangement or cerebrospinal fluid abnormalities, and her consciousness was clear during the interictal period. Those findings were consistent with CwG. As transient splenial lesions were not accompanied by any neurological abnormalities other than seizures, she was not diagnosed as having encephalopathy, but as having CwG. Diffusion-weighted magnetic resonance imaging of the brain demonstrated hyperintense lesions in the splenium of the corpus callosum, which disappeared within a week. We speculate that CwG is likely to lead to transient splenial lesions.

Circulating muscle-specific microRNA, miR-206, as a potential diagnostic marker for rhabdomyosarcoma

Presently there is no serum biomarker of rhabdomyosarcoma (RMS). Several studies have shown that profiles of microRNA (miRNA) expression differ among tumor types. Here we evaluated the feasibility of using muscle-specific miRNAs (miR-1, -133a, -133b and -206) as biomarkers of RMS. Expression of muscle-specific miRNAs, especially miR-206, was significantly higher in RMS cell lines than in other tumor cell lines, as well as in RMS tumor specimens. Further, serum levels of muscle-specific miRNAs were significantly higher in patients with RMS tumors than in patients with non-RMS tumors. Normalized serum miR-206 expression level could be used to differentiate between RMS and non-RMS tumors, with sensitivity of 1.0 and specificity of 0.913. These results raise the possibility of using circulating muscle-specific miRNAs, especially miR-206, as landmark biomarkers for RMS.

Effects of stress of postnatal development on corticosterone, serotonin and behavioral changes

Stressful events early in life are associated with later psychiatric disorders. We focused on developmental stage and evaluated changes in the corticosterone and serotonergic systems as well as in later anxiety-related behavioral tests. Stressed male Wistar rats were divided into two groups: stressed from postnatal day 11 (PND 11) to 15 and stressed from PND 16 to 20. The rats were exposed to an elevated open platform. Stress increased corticosterone in both experimental groups. In the hypothalamus, amygdala and hippocampus, 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) increased in the rats stressed from PND 11 to 15, and decreased in the rats stressed from PND 16 to 20. In a later behavioral test, rats stressed from PND 11 to 15 traveled shorter distances and tended to spend less time in the center than control rats following restraint stress. There were no significant changes in 5-HT and 5-HIAA in hypothalamus, amygdala and hippocampus after restraint stress in adults. These findings indicate that stress reactions and later effects are different depending on the developmental stage during which the rats were stressed. Stress during the PND 11-15 period may enhance later anxiety-related behaviors without altering 5-HT and 5-HIAA content.

Abstract 4842: Lysosomal-associated protein multispanning transmembrane 5 gene (LAPTM5) is associated with spontaneous regression of neuroblastomas

Background; Neuroblastoma (NB) is the most frequently occurring solid tumor in children, and shows heterogeneous clinical behavior. Favorable tumors, which are usually detected by mass screening based on increased levels of catecholamines in urine, regress spontaneously via programmed cell death (PCD) or mature through differentiation into benign ganglioneuroma (GN). In contrast, advanced-type NB tumors often grow aggressively, despite intensive chemotherapy. Understanding the molecular mechanisms of PCD during spontaneous regression in favorable NB tumors, as well as identifying genes with a pro-death role, is a matter of urgency for developing novel approaches to the treatment of advanced-type NB tumors.

Key findings; We found that the expression of lysosomal associated protein multispanning transmembrane 5 (LAPTM5) was usually down-regulated due to DNA methylation in an NB cell-specific manner, but up-regulated in degenerating NB cells within locally regressing areas of favorable tumors detected by mass-screening. Experiments in vitro showed that not only a restoration of its expression but also the accumulation of LAPTM5 protein, was required to induce non-apoptotic cell death with autophagic vacuoles and lysosomal destabilization with lysosomal-membrane permeabilization (LMP) in a caspase-independent manner. While autophagy is a membrane-trafficking pathway to degrade the proteins in lysosomes, the LAPTM5-mediated lysosomal destabilization with LMP leads to an interruption of autophagic flux, resulting in the accumulation of immature autophagic vacuoles, p62/SQSTM1, and ubiqitinated proteins as substrates of autophagic degradation. In addition, ubiquitin-positive inclusion bodies appeared in degenerating NB cells.

Conclusions; We propose a novel molecular mechanism for PCD with the accumulation of autophagic vacuoles due to LAPTM5-mediated lysosomal destabilization. LAPTM5-induced cell death is lysosomal cell death with impaired autophagy, not cell death by autophagy, so-called autophagic cell death. Thus LAPTM5-mediated PCD is closely associated with the spontaneous regression of NBs and opens new avenues for exploring innovative clinical interventions for this tumor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4842.

Lysosomal-associated protein multispanning transmembrane 5 gene (LAPTM5) is associated with spontaneous regression of neuroblastomas

Background

Neuroblastoma (NB) is the most frequently occurring solid tumor in children, and shows heterogeneous clinical behavior. Favorable tumors, which are usually detected by mass screening based on increased levels of catecholamines in urine, regress spontaneously via programmed cell death (PCD) or mature through differentiation into benign ganglioneuroma (GN). In contrast, advanced-type NB tumors often grow aggressively, despite intensive chemotherapy. Understanding the molecular mechanisms of PCD during spontaneous regression in favorable NB tumors, as well as identifying genes with a pro-death role, is a matter of urgency for developing novel approaches to the treatment of advanced-type NB tumors.

Principal Findings

We found that the expression of lysosomal associated protein multispanning transmembrane 5 (LAPTM5) was usually down-regulated due to DNA methylation in an NB cell-specific manner, but up-regulated in degenerating NB cells within locally regressing areas of favorable tumors detected by mass-screening. Experiments in vitro showed that not only a restoration of its expression but also the accumulation of LAPTM5 protein, was required to induce non-apoptotic cell death with autophagic vacuoles and lysosomal destabilization with lysosomal-membrane permeabilization (LMP) in a caspase-independent manner. While autophagy is a membrane-trafficking pathway to degrade the proteins in lysosomes, the LAPTM5-mediated lysosomal destabilization with LMP leads to an interruption of autophagic flux, resulting in the accumulation of immature autophagic vacuoles, p62/SQSTM1, and ubiqitinated proteins as substrates of autophagic degradation. In addition, ubiquitin-positive inclusion bodies appeared in degenerating NB cells.

Conclusions

We propose a novel molecular mechanism for PCD with the accumulation of autophagic vacuoles due to LAPTM5-mediated lysosomal destabilization. LAPTM5-induced cell death is lysosomal cell death with impaired autophagy, not cell death by autophagy, so-called autophagic cell death. Thus LAPTM5-mediated PCD is closely associated with the spontaneous regression of NBs and opens new avenues for exploring innovative clinical interventions for this tumor.

Restoration of p53 pathway by nutlin-3 induces cell cycle arrest and apoptosis in human rhabdomyosarcoma cells

PURPOSE

Seventy to eighty percent of rhabdomyosarcoma (RMS) tumors retain wild-type p53. The tumor suppressor p53 plays a central role in inducing cell cycle arrest or apoptosis in response to various stresses. p53 protein levels are regulated by MDM2 through ubiquitin-dependent degradation. In this study, we evaluated whether nutlin-3, a recently developed small-molecule antagonist of MDM2, has an effect on p53-dependent cell cycle arrest and apoptosis in cultured human RMS cell lines.

EXPERIMENTAL DESIGN

Five RMS cell lines with different p53 statuses and MDM2 expression levels were treated with nutlin-3. Gene expression patterns, cell viability, cell cycle, and apoptosis after nutlin-3 treatment, and antitumor activity of combination treatment with vincristine or actinomycin D were assessed.

RESULTS

Significant p53 activation was observed in wild-type p53 cell lines after nutlin-3 treatment. p53 activation led to cell cycle arrest in parallel with increased p21 expression. Furthermore, these cell lines underwent p53-dependent apoptosis, concomitant with elevation of proapoptotic genes and activation of caspase-3. The effect of nutlin-3 was almost the same in terms of half maximal inhibitory concentration and apoptosis whether or not MDM2 was overexpressed. Nutlin-3 did not induce either cell cycle arrest or apoptosis in p53 mutant cell lines. A combination of vincristine or actinomycin D with nutlin-3 enhanced the antitumor activity in RMS cell lines with wild-type p53.

CONCLUSIONS

Nutlin-3 effectively restored p53 function in both normal MDM2 expression and MDM2 overexpression RMS cell lines with wild-type p53. p53 restoration therapy is a potential therapeutic strategy for refractory RMS with wild-type p53.

RASSF1A hypermethylation in pretreatment serum DNA of neuroblastoma patients: a prognostic marker

The tumour suppressor gene RASSF1A is known to be frequently silenced by promoter hypermethylation in neuroblastoma tumours. Here we explored the possible prognostic significance of aberrant promoter hypermethylation of RASSF1A in serum DNA samples of patients with neuroblastoma as a surrogate marker for circulating tumour cells. We analysed the methylation status of the RASSF1A gene in matched tumour and pretreatment serum DNA obtained from 68 neuroblastoma patients. Hypermethylation of RASSF1A in tumour samples was found in 64 patients (94%). In contrast, serum methylation of RASSF1A was observed in 17 patients (25%). Serum methylation of RASSF1A was found to be statistically associated with age ⩾12 months at diagnosis (P=0.002), stage 4 (P<0.001) and MYCN amplification (P<0.001). The influence of serum RASSF1A methylation on prognosis was found to be comparable with that of the currently most reliable marker, MYCN amplification on univariate analysis (hazard ratio, 9.2; 95% confidence interval (CI), 2.8–30.1; P<0.001). In multivariate analysis of survival, methylation of RASSF1A in serum had a hazard ratio of 2.4 (95% CI, 0.6–9.2), although this association did not reach statistical significance (P=0.194). These findings show that the methylation status of RASSF1A in the serum of patients with neuroblastoma has the potential to become a prognostic predictor of outcome.

A novel PAX3 rearrangement in embryonal rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft tissue tumor seen in children and young adults, and it can be classified into 2 major histological subtypes, alveolar and embryonal. In the alveolar subtype, 2 recurrent chromosomal translocations, t(2;13)(q35;q14) and its variant t(1;13)(p36;q14), have been identified as the specific cytogenetic abnormalities. These translocations produce the PAX3-FOXO1 and PAX7-FOXO1 fusion genes, respectively. In the embryonal subtype, however, no recurrent chromosomal abnormalities have been identified. In this study, we analyzed the complex chromosomal translocation in one case with embryonal rhabdomyosarcoma by means of spectral karyotyping (SKY) and identified a novel translocation involving chromosome band 2q35, which is the locus of PAX3 gene. Furthermore, we identified the novel PAX3 rearrangement using fluorescence in situ hybridization (FISH) analysis. Additional identification of the partner gene may help disclose the molecular mechanism of the development of this embryonal subtype.

Induction of autophagy in malignant rhabdoid tumor cells by the histone deacetylase inhibitor FK228 through AIF translocation

Malignant rhabdoid tumors (MRT) exhibit a very poor prognosis because of their resistance to chemotherapeutic agents and new therapies are needed for the treatment of this cancer. Here, we show that the histone deacetylase (HDAC) inhibitor FK228 (depsipeptide) has an antitumor effect on MRT cells both in vitro and in vivo. FK228 is a unique cyclic peptide and is among the most potent inhibitors of both Class I and Class II HDACs. FK228 inhibited proliferation and induced apoptosis in all MRT cell lines tested. Preincubation with the pancaspase inhibitor zVAD-fmk did not completely rescue FK228-induced cell death, although it did inhibit apoptosis. Transmission electron microscopy (TEM) showed that FK228 could stimulate MRT cells to undergo apoptosis, necrosis or autophagy. FK228 converted unconjugated microtubule-associated protein light chain 3 (LC3-I) to conjugated light chain 3 (LC3-II) and induced localization of LC3 to autophagosomes. Apoptosis inducing factor (AIF), which plays a role in caspase-independent cell death, translocated to the nucleus in response to FK228 treatment. Moreover, small interfering RNA (siRNA) targeting of AIF prevented the morphological changes associated with autophagy and redistribution of LC3 to autophagosomes. Disrupting autophagy with chloroquine treatment enhanced FK228-induced cell death. In vivo, FK228 caused a reduction in tumor size and induced autophagy in tumor tissues. Using immunoelectron microscopy, we confirmed AIF translocation into the nucleus of FK228-induced autophagic cells in vivo. Thus, FK228 is a novel candidate for an antitumor agent for MRT cells.

A new therapeutic modality involving acridine orange excitation by photon energy used during reduction surgery for rhabdomyosarcomas

Rhabdomyosarcoma is a common malignant soft tissue that frequently involves bone and major neurovascular structures and resection of deep-seated rhabdomyosarcoma can cause severe dysfunction in the affected limbs. Based on the mouse osteosarcoma model, we developed a new surgical approach involving photodynamic surgery (PDS), photodynamic therapy (PDT) and radiodynamic therapy (RDT) using acridine orange (AO). Six rhabdomyosarcoma cases were treated using this new modality after confirming the effectiveness of AO-PDT on human rhabdomyosarcoma cell lines. All patients had almost normal limb function after surgery, with only one recurrence. Based on these results, AO-PDS, PDT and RDT can be used to preserve excellent limb function in patients with rhabdomyosarcoma involving major nerves and vessels or bones.

Circulating methylated-DCR2 gene in serum as an indicator of prognosis and therapeutic efficacy in patients with MYCN nonamplified neuroblastoma

BACKGROUND

MYCN amplification (MNA) in neuroblastoma is a strong indicator of poor prognosis. However, some MYCN nonamplified (non-MNA) cases show poor outcomes, and examining the status of the gene requires an operation, which may have surgical complications. Therefore, a new marker is needed to identify cases of non-MNA neuroblastomas with poor prognoses using less risky procedures. Aberrant hypermethylation of the DCR2 promoter has recently been associated with rapidly progressing neuroblastoma. We aimed to develop a noninvasive DCR2 methylation assay for patients with neuroblastoma using serum DNA, which predominantly originates from tumor-released DNA.

METHODS

Using DNA-based real-time PCR, we simultaneously quantified a methylated-DCR2 specific sequence (M) and a reference sequence (R) located in the promoter region in serum DNA, and evaluated DCR2 methylation status as M/R ratios in 86 patients with neuroblastoma.

RESULTS

Serum DCR2 M/R ratios were strongly correlated with those in the tumor (r=0.67; P=0.002). DCR2 methylation was associated with stage both in the whole neuroblastoma group and in the non-MNA group (P<0.001), and DCR2-methylated patients showed significantly poorer 5-year event-free survival in the whole neuroblastoma group (43% versus 84%; P<0.001), especially in the non-MNA group (12% versus 96%;P<0.001). Among five DCR2-methylated patients whose clinical courses were followed, serum M/R ratios were close to 0 in the patients in remission, whereas the ratios increased in patients who relapsed.

CONCLUSIONS

Detection of methylated-DCR2 in serum DNA has promise as a noninvasive assay for predicting prognosis and therapeutic efficacy in neuroblastoma, especially in non-MNA cases. Furthermore, it might be a sensitive marker of tumor recurrence in DCR2-methylated cases.