Prognostic discrimination among neuroblastomas according to Ha-ras/trk A gene expression: a comparison of the profiles of neuroblastomas detected clinically and those detected through mass screening

Ras and autophagy in cancer development and therapy

Autophagy, a process of self-degradation and turnover of cellular components, plays a complex role in cancer. Evidence exists to show that autophagy may support tumor growth and cell survival, whereas it can also contribute to tumor suppression and have anti-survival characteristics in different cellular systems. Numerous studies have described the effects of various oncogenes and tumor suppressors on autophagy. The small GTPase Ras is an oncogene involved in the regulation of various cell-signaling pathways, and is mutated in 33% of human cancers. In the present review, we discuss the interplay between Ras and autophagy in relation to oncogenesis. It appears that Ras can upregulate or downregulate autophagy through several signaling pathways. In turn, autophagy can affect the tumorigenicity driven by Ras, resulting in either tumor progression or repression, depending on the cellular context. Furthermore, Ras inhibitors were shown to induce autophagy in several cancer cell lines.

Death pathways triggered by activated Ras in cancer cells

Ras GTPases are best known for their ability to serve as molecular switches regulating cell growth, differentiation and survival. Gene mutations that result in expression of constitutively active forms of Ras have been linked to oncogenesis in animal models and humans. However, over the past two decades, evidence has gradually accumulated to support a paradoxical role for Ras proteins in the initiation of cell death pathways. In this review we survey the literature pointing to the ability of activated Ras to promote cell death under conditions where cancer cells encounter apoptotic stimuli or Ras is ectopically expressed. In some of these cases Ras acts through known effectors and well defined apoptotic death pathways. However, in other cases it appears that Ras operates by triggering novel non-apoptotic death mechanisms that are just beginning to be characterized. Understanding these mechanisms and the factors that go into changing the nature of Ras signaling from pro-survival to pro-death could set the stage for development of novel therapeutic approaches aimed at manipulating pro-death Ras signaling pathways in cancer.

Expression of the neuron-specific protein CHD5 is an independent marker of outcome in neuroblastoma

Background

The chromodomain, helicase DNA-binding protein 5 (CHD5) is a potential tumor suppressor gene located on chromosome 1p36, a region recurrently deleted in high risk neuroblastoma (NB). Previous data have shown that CHD5 mRNA is present in normal neural tissues and in low risk NB, nevertheless, the distribution of CHD5 protein has not been explored. The aim of this study was to investigate CHD5 protein expression as an immunohistochemical marker of outcome in NB. With this purpose, CHD5 protein expression was analyzed in normal neural tissues and neuroblastic tumors (NTs). CHD5 gene and protein expression was reexamined after induction chemotherapy in a subset of high risk tumors to identify potential changes reflecting tumor response.

Results

We provide evidence that CHD5 is a neuron-specific protein, absent in glial cells, with diverse expression amongst neuron types. Within NTs, CHD5 immunoreactivity was found restricted to differentiating neuroblasts and ganglion-like cells, and absent in undifferentiated neuroblasts and stromal Schwann cells. Correlation between protein and mRNA levels was found, suggesting transcriptional regulation of CHD5. An immunohistochemical analysis of 90 primary NTs highlighted a strong association of CHD5 expression with favorable prognostic variables (age at diagnosis <12 months, low clinical stage, and favorable histology; P < 0.001 for all), overall survival (OS) (P < 0.001) and event-free survival (EFS) (P < 0.001). Multivariate analysis showed that CHD5 prognostic value is independent of other clinical and biologically relevant parameters, and could therefore represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. The prognostic value of CHD5 was confirmed in an independent, blinded set of 32 NB tumors (P < 0.001).

Reactivation of CHD5 expression after induction chemotherapy was observed mainly in those high risk tumors with induced tumor cell differentiation features. Remarkably, these NB tumors showed good clinical response and prolonged patient survival.

Conclusions

The neuron-specific protein CHD5 may represent a marker of outcome in NB that can be tested by conventional immunohistochemistry. Re-establishment of CHD5 expression induced by chemotherapy could be a surrogate marker of treatment response.

Activation of Erk1/2 phosphorylation but not of Akt/Pkb through an inducible CSF1R/IRR-receptor construct in INS-1E beta-cells

CONTEXT

The insulin receptor-related receptor (IRR) is an orphan receptor belonging to the insulin receptor (IR) family. Despite its unknown function, the specific tissue expression and the high sequence homology with the IR and the insulin-like growth factor 1 receptor (IGF1R) suggest a biological role in beta-cells.

OBJECTIVES

In this study we investigated the influence of a stimulatable IRR-tyrosine kinase on major IR/IGF1R signaling pathways and on proliferation and apoptosis of INS-1E beta-cells.

METHODS

INS-1E cells were stably transfected with a colony stimulating factor 1 receptor (CSF1R)/IRR construct activated by a macrophage colony stimulating factor.

RESULTS AND CONCLUSION

After stimulation the construct showed time and dose dependent autophosphorylation and transient extracellular signal regulated kinase 1/2 activation. Protein kinase b was not phosphorylated and also an effect on proliferation and apoptosis of INS-1E could not be demonstrated. Thus, no obvious biologic function of the IRR is present in INS-1E beta-cells.

c.1810C>T polymorphism of NTRK1 gene is associated with reduced survival in neuroblastoma patients

Background

TrkA (encoded by NTRK1 gene), the high-affinity tyrosine kinase receptor for neurotrophins, is involved in neural crest cell differentiation. Its expression has been reported to be associated with a favourable prognosis in neuroblastoma. Therefore, the entire coding sequence of NTRK1 gene has been analysed in order to identify mutations and/or polymorphisms which may alter TrkA receptor expression.

Methods

DNA was extracted from neuroblastomas of 55 Polish and 114 Italian patients and from peripheral blood leukocytes of 158 healthy controls. Denaturing High-Performance Liquid Chromatography (DHPLC) and Single-Strand Conformation Polymorphism (SSCP) analysis were used to screen for sequence variants. Genetic changes were confirmed by direct sequencing and correlated with biological and clinical data.

Results

Three previously reported and nine new single nucleotide polymorphisms were detected. c.1810C>T polymorphism present in 8.7% of cases was found to be an independent marker of disease recurrence (OR = 13.3; p = 0.009) associated with lower survival rates (HR = 4.45 p = 0.041). c.1810C>T polymorphism's unfavourable prognostic value was most significant in patients under 18 months of age with no MYCN amplification (HR = 26; p = 0.008). In-silico analysis of the c.1810C>T polymorphism suggests that the substitution of the corresponding amino acid residue within the conservative region of the tyrosine kinase domain might theoretically interfere with the functioning of the TrkA protein.

Conclusions

NTRK1 c.1810C>T polymorphism appears to be a new independent prognostic factor of poor outcome in neuroblastoma, especially in children under 18 months of age with no MYCN amplification.

Analyses of novel prognostic factors in neuroblastoma patients

Neuroblastoma (NB) is the most common malignant solid tumor in childhood. There are well-recognized prognostic factors in NB such as age at diagnosis, organ of origin, stages, MYCN gene amplification, and expression of H-ras, trkA and survivin. Moreover, we investigated the expression of vascular endothelial growth factor (VEGF), tyrosine hydroxylase (TH), p53, stem cell factor (SCF) and c-kit of its receptor with quantitative real-time polymerase chain reaction (PCR) in 22 NBs and 4 other tumors (one malignant lymphoma, one malignant teratoma, and 2 rhabdomyosarcomas) samples. The correlation between patients' prognoses and the expression of TH or c-kit was newly recognized, particularly the good prognosis in patients in whom c-kit highly expressed and the poor prognosis contrarily associated with low or no expression, although the SCF of its ligand had no relationship with patient prognosis. It is possible that tumors without c-kit expression can not react with SCF (via the autocrine or paracrine system) and remain immature. It may be that this is a new critical clinical event in NB patients.

MYCN gene amplification is a powerful prognostic factor even in infantile neuroblastoma detected by mass screening

MYCN is the most powerful prognostic factor in cases of older children. However, how MYCN is related to the prognosis of infantile cases is not clear. A mass screening program was carried out by measuring urinary catecholamine metabolites (VMA and HVA) from 6-month-old infants. Of 2084 cases detected by the screening program, MYCN amplification (MNA) was examined by Southern blot analyses in 1533 cases from 1987 to 2000. Of the 1533 cases examined, 1500 (97.8%) showed no MNA, 20 cases (1.3%) showed MNA from three to nine copies, and 13 (0.8%) cases showed more than 10 copies. The 4-year overall survival rates of these three groups (99, 89 and 53%, respectively) were significantly different (P<0.001), indicating that MYCN copy number correlates with the prognosis. Cases with MNA more than 10 copies were more advanced than those without amplification (stage III, IV vs I, II, IVs; P<0.001). Patients with MNA more than 10 copies had significantly higher serum levels of neuron-specific-enolase (NSE) and ferritin than non-amplified patients (P=0.049, P=0.025, respectively). MYCN amplification was strongly correlated with a poor prognosis in infantile neuroblastoma cases. Therefore, for the selection of appropriate treatment, an accurate determination of MNA is indispensable.

Increased expression of proapoptotic BMCC1, a novel gene with the BNIP2 and Cdc42GAP homology (BCH) domain, is associated with favorable prognosis in human neuroblastomas

Differential screening of the genes obtained from cDNA libraries of primary neuroblastomas (NBLs) between the favorable and unfavorable subsets has identified a novel gene BCH motif-containing molecule at the carboxyl terminal region 1 (BMCC1). Its 350 kDa protein product possessed a Bcl2-/adenovirus E1B nineteen kDa-interacting protein 2 (BNIP2) and Cdc42GAP homology domain in the COOH-terminus in addition to P-loop and a coiled-coil region near the NH2-terminus. High levels of BMCC1 expression were detected in the human nervous system as well as spinal cord, brain and dorsal root ganglion in mouse embryo. The immunohistochemical study revealed that BMCC1 was positively stained in the cytoplasm of favorable NBL cells but not in unfavorable ones with MYCN amplification. The quantitative real-time reverse transcription-PCR using 98 primary NBLs showed that high expression of BMCC1 was a significant indicator of favorable NBL. In primary culture of newborn mice superior cervical ganglion (SCG) neurons, mBMCC1 expression was downregulated after nerve growth factor (NGF)-induced differentiation, and upregulated during the NGF-depletion-induced apoptosis. Furthermore, the proapoptotic function of BMCC1 was also suggested by increased expression in CHP134 NBL cells undergoing apoptosis after treatment with retinoic acid, and by an enhanced apoptosis after depletion of NGF in the SCG neurons obtained from newborn mice transgenic with BMCC1 in primary culture. Thus, BMCC1 is a new member of prognostic factors for NBL and may play an important role in regulating differentiation, survival and aggressiveness of the tumor cells.

A review of DNA microarray analysis of human neuroblastomas

Neuroblastoma (NBL) is an enigmatic tumor with heterogeneous clinical behaviors including maturation, regression, and aggressive growth. Despite recent progress in therapeutic strategies against advanced NBL, long-term outcomes still remain very poor. The prediction of cancer prognosis is one of the most urgent demands to initiate the suitable treatment of NBL. Recent papers have demonstrated that cancers can be diagnosed on the basis of gene expression profiling. We have been proceeded NBL cDNA project to collect a large number of genes expressed in NBLs, to identify the genes differentially expressed between favorable and unfavorable NBLs, and to make an NBL-proper cDNA chip for large-scale analysis of NBL tumors. Computational analysis of gene expression data in NBLs identified many prognosis-related genes and provided a classifier to predict the patient prognosis with high efficiency. Conversion of these findings into better diagnosis and treatment is now underway. Thus, molecular profiling of NBL has become a feasible tool for clinical applications.

Diversity in neuroblastomas and discrimination of the risk to progress

The clinical diversity of Neuroblastomas (NBs) was discriminated into three groups with high sensitivity and specificity to patient's outcome. The 'high risk' NB is defined with any of following conditions, MYCN amplification or unfavorable histology of International Neuroblastoma Pathological Classification (INPC) or low Ha-ras/trk A expression. The 'low risk' NB is defined with all following conditions, single copy of MYCN and INPC favorable histology and high Ha-ras/trk A expression and localized tumor. The remaining NBs were classified into 'intermediate risk' ones. According to these criteria, the diversity of the 248 mass-screening NBs was shown with variety progressive risk; 40% were classified in low risk group, 25% were in high risk group and 35% were in intermediate risk group.

Significance of survivin mRNA expression in prognosis of neuroblastoma

Neuroblastoma (NB) is the most common malignant solid tumor in childhood, and among all childhood malignancies is second in prevalence only to leukemia. In NB we need to both make an accurate diagnosis and rapidly analyze the expression of genetic prognostic factors such as MYCN, H-ras, and trkA. Moreover, it has recently become important to analyze the expression of survivin mRNA, a member of the inhibitor of apoptosis protein family. Expression of the survivin gene is related to tumorigenesis and inhibition of apoptosis in some malignant tumors. We investigated its expression by reverse transcription-polymerase chain reaction (RT-PCR) in NB cell lines (SK-N-SH, NB-39, and IMR-32), two normal blood cell samples, and 13 clinical NB tumor samples. All three NB cell lines had high levels of mRNA expression for this gene, but normal blood cells had no expression. We detected expression of survivin mRNA in 7 of the 13 NB tumor samples (54%). Two NB patients were in stage I disease, 6 in stage II, and 5 in stage IV(A). Quantitative analysis by RT-PCR revealed that the ratio between survivin mRNA and human glyceraldehyde-3-phosphate dehydrogenase (h-GAPDH) mRNA was very low in stages I and II (0-0.017). In contrast, in advanced NBs (stage IV(A)) the ratio was much higher (0-0.050). The prognoses of the three patients in the advanced stage who had high ratios of expression were poor. A high level of expression of survivin mRNA indicates a high grade of malignancy, high likelihood of recurrence, and poor prognosis.

Profile of neuroblastoma detected by mass screening, resected after observation without treatment: results of the Wait and See pilot study

BACKGROUND/PURPOSE

Neuroblastoma (NB) detected by mass screening (MS) usually shows favorable prognosis and sometimes regresses spontaneously. Therefore, the authors started an observation program for these patients to avoid overtreatment. In this study, the authors analyzed the profile of NB resected after observation to elucidate the nature of NB detected by MS.

METHODS

Between 1994 and 2004, 22 NB patients matched the following criteria and entered the observation program after obtaining informed consent: stage I or II, less than 5 cm in diameter, and without involvement of large vessels or organs. If increase in size, elevation of tumor markers, or evidence of metastasis was observed, the tumor was immediately resected.

RESULTS

Thirteen (59%) of 22 cases showed spontaneous regression. In the remaining 9 cases, tumors were resected because of parents' request, increase in size, and/or elevation of tumor markers. Four tumors had at least one unfavorable biologic feature, and 3 of them had more than 2. According to Shimada's system, 2 had unfavorable histology. One was diploid tumor, 3 had 1p deletion, and Trk-A expression was low in 4 tumors. All patients survived without evidence of recurrence.

CONCLUSIONS

The observation program has shown that at least one third of the NB detected by MS regressed spontaneously. On the other hand, MS may detect some cases with unfavorable tumor in early stage, which benefit from screening.

Gene expression profiling and identification of novel prognostic marker genes in neuroblastoma

To investigate the various genetic characteristics of and differences between early- and advanced-stage neuroblastoma (NB) and to identify candidate genes involved in NB progression, we performed DNA microarray analysis on 20 primary tumors. Two-way clustering analysis based on the expression pattern of approximately 500 of 1,700 genes revealed genetic subgroups in these NB tumors. Although 9 of the 13 early-stage tumors (69%) and 4 of the 6 advanced-stage tumors (67%) were classified as being in the same cluster, the remaining tumors showed different expression profiles. This indicates that both the early- and advanced-stage tumors were heterogeneous. Based on the microarray data, we identified the BIRC, CDKN2D, and SMARCD3 genes as those that are predominantly expressed in either the early or the advanced stage of NB. These genes have been reported to be associated with apoptosis, cell cycles, and the transcriptional activator, respectively. To better assess the prognostic value of the expression of these genes in NB, real-time polymerase chain reaction was carried out on 50 primary tumors. The expression of both the BIRC3 and CDKN2D genes was significantly higher in the early-stage group than in the advanced-stage group (P = 0.002 and 0.003, respectively), whereas the expression of the SMARCD3 gene was significantly reduced in the early-stage group (P = 0.02). Therefore, the BIRC, CDKN2D, and SMARCD3 genes are possible candidates for being novel prognostic markers for NB.

The Ews/Fli-1 fusion gene switches the differentiation program of neuroblastomas to Ewing sarcoma/peripheral primitive neuroectodermal tumors

Neuroblastoma (NB) and the Ewing sarcoma (ES)/peripheral primitive neuroectodermal tumor (PNET) family are pediatric cancers derived from neural crest cells. Although NBs display features of the sympathetic nervous system, ES/PNETs express markers consistent with parasympathetic differentiation. To examine the control of these differentiation markers, we generated NB x ES/PNET somatic cell hybrids. NB-specific markers were suppressed in the hybrids, whereas ES/PNET-specific markers were unaffected. These results suggested that the Ews/Fli-1 fusion gene, resulting from a translocation unique to ES/PNETs, might account for the loss of NB-specific markers. To test this hypothesis, we generated two different NB cell lines that stably expressed the Ews/Fli-1 gene. We observed that heterologous expression of the Ews/Fli-1 protein led to the suppression of NB-specific markers and de novo expression of ES/PNET markers. To determine the extent of changes in differentiation, we used the Affymetrix GeneChip Array system to observe global transcriptional changes of genes. This analysis revealed that the gene expression pattern of the Ews/Fli-1-expressing NB cells resembled that observed in pooled ES/PNET cell lines and differed significantly from the NB parental cells. Therefore, we propose that Ews/Fli-1 contributes to the etiology of ES/PNET by subverting the differentiation program of its neural crest precursor cell to a less differentiated and more proliferative state.

Pediatric neuroblastomas: genetic and epigenetic 'danse macabre'

Neuroblastomas are the most frequently occurring solid tumors in children under 5 years. Spontaneous regression is more common in neuroblastomas than in any other tumor type, especially in young patients under 12 months. Unfortunately, the full clinical spectrum of neuroblastomas also includes very aggressive tumors, unresponsive to multi-modality treatment and accounting for most of the pediatric cancer mortalities under 5 years of age. It is generally emphasized that more than one biological entity of neuroblastoma exists. Structural genetic defects such as amplification of MYCN, gain of chromosome 17q and LOH of 1p and several other chromosomal regions have proven to be valuable as prognostic factors and will be discussed in relation to their clinical relevance. Recent research is starting to uncover important molecular pathways involved in the pathogenesis of neuroblastomas. The aim of this review is to discuss several important aspects of the biology of the neuroblast, such as the role of overexpressed oncogenes like MYCN and cyclin D1, the mechanisms leading to decreased apoptosis, like overexpression of BCL-2, survivin, NM23, epigenetic silencing of caspase 8 and the role of tumor suppressor genes, like p53, p73 and RASSF1A. In addition, the role of specific proteins overexpressed in neuroblastomas, such as the neurotrophin receptors TrkA, B and C in relation to spontaneous regression and anti-angiogenesis will be discussed. Finally, we will try to relate these pathways to the embryonal origin of neuroblastomas and discuss possible new avenues in the therapeutic approach of future neuroblastoma patients.

Usefulness of Tyrosine Hydroxylase mRNA for Diagnosis and Detection of Minimal Residual Disease in Neuroblastoma

Neuroblastoma (NB) is the most common malignant solid tumor in childhood and, among all childhood malignancies, is second only to leukemia. NB originates before birth in the neural crest, which develops into the adrenal medullae and sympathetic ganglia. In the adrenal medulla, tyrosine hydroxylase (TH) is the first enzyme in the pathway of catecholamine synthesis. We used reverse transcription polymerase chain reaction (RT-PCR) to examine the expression of TH mRNA in NB and Ewing's sarcoma cell lines, small round cell tumors (SRCTs) containing NB, and other clinical tumor samples (osteosarcoma, osteochondroma, and Wilms' tumor). In total, we analyzed 33 clinical tumor samples. TH mRNA was expressed in all three NB cell lines examined, but not in two ES cell lines or in a breast cancer cell line. We detected TH mRNA in 23 of 25 NB tumor samples (92%), but in none of the SRCTs or other clinical tumor samples. This RT-PCR technique showed a sensitivity for TH mRNA of one NB cell per 10(5) negative cells. Based on these results, the detection of TH mRNA is very useful both as a tumor marker for NB and for detecting minimal residual disease. Therefore, we can use this method to detect tumor cell contamination before hematopoietic stem cell transplantation.

Genetic parameters of neuroblastomas

Neuroblastoma is a malignant childhood tumor of migrating neuroectodermal cells derived from the neural crest and destined for the adrenal medulla and the sympathetic nervous system. The biological behavior of neuroblastomas is extremely variable and in some respects unique. Neuroblastomas tend to regress spontaneously in a portion of infants or to differentiate into a benign ganglioneuroma in some older patients. Unfortunately, in the majority of patients neuroblastoma is metastatic at the time of diagnosis, and it usually undergoes rapid progression with a fatal outcome. The mechanisms leading to this diverse clinical behavior of neuroblastomas are largely unclear. From the analysis of tumors at the cytogenetic and molecular level non-random genetic changes have been identified, including ploidy changes, amplification of the oncogene MYCN, deletions of chromosome 1p, gains of chromosome arm 17q, and deletions of 11q as well as of other genomic regions that allow tumors to be classified into subsets with distinct biological features and clinical behavior. MYCN status is widely accepted for therapy stratification. Additional genetic parameters are currently under investigation to refine risk assessment, but so far the molecular monitoring tools for prediction of therapy response and disease outcome are still incomplete. This should lead to more risk-adapted therapies according to the clinical-genetic parameters by which individual tumors are characterized. This review aims at discussing the role of genomic changes in neuroblastomas of diverse biological and clinical types.

RASSF1A promoter region CpG island hypermethylation in phaeochromocytomas and neuroblastoma tumours

Deletions of chromosome 3p are frequent in many types of neoplasia including neural crest tumours such as neuroblastoma (NB) and phaeochromocytoma. Recently we isolated several candidate tumour suppressor genes (TSGs) from a 120 kb critical interval at 3p21.3 defined by overlapping homozygous deletions in lung and breast tumour lines. Although mutation analysis of candidate TSGs in lung and breast cancers revealed only rare mutations, expression of one of the genes (RASSF1A) was absent in the majority of lung tumour cell lines analysed. Subsequently methylation of a CpG island in the promoter region of RASSF1A was demonstrated in a majority of small cell lung carcinomas and to a lesser extent in non-small cell lung carcinomas. To investigate the role of 3p TSGs in neural crest tumours, we (a) analysed phaeochromocytomas for 3p allele loss (n=41) and RASSF1A methylation (n=23) and (b) investigated 67 neuroblastomas for RASSF1A inactivation. 46% of phaeochromocytomas showed 3p allele loss (38.5% at 3p21.3). RASSF1A promoter region hypermethylation was found in 22% (5/23) of sporadic phaeochromocytomas and in 55% (37/67) of neuroblastomas analysed but RASSF1A mutations were not identified. In two neuroblastoma cell lines, methylation of RASSF1A correlated with loss of RASSF1A expression and RASSF1A expression was restored after treatment with the demethylating agent 5-azacytidine. As frequent methylation of the CASP8 gene has also been reported in neuroblastoma, we investigated whether RASSF1A and CASP8 methylation were independent or related events. CASP8 methylation was detected in 56% of neuroblastomas with RASSF1A methylation and 17% without RASSF1A methylation (P=0.0031). These results indicate that (a) RASSF1A inactivation by hypermethylation is a frequent event in neural crest tumorigenesis, particularly neuroblastoma, and that RASSF1A is a candidate 3p21.3 neuroblastoma TSG and (b) a subset of neuroblastomas may be characterized by a CpG island methylator phenotype.

Clinical and biologic characteristics for recurring neuroblastoma at mass screening cases in Japan

BACKGROUND

It is said that most cases detected by neuroblastoma mass screening at 6 months of age tend to have a favorable clinical course after a surgical resection either with or without mild chemotherapy. However, a few cases have an unfavorable outcome. In the current study, the authors analyzed the clinical and biologic characteristics for recurring neuroblastoma in mass screening cases.

METHODS

In 245 cases detected through mass screening in the Kyushu area in Japan, the clinical data and biologic features (N-myc status, DNA ploidy, Shimada histology, neuron-specific enolase (NSE), ferritin) were investigated, whereas, in particular, the data for recurring cases also were analyzed.

RESULTS

Of 245 cases, 28 tumors had one or more biologically unfavorable prognostic factors, and 6 patients experienced recurrence. Three of the six patients with recurring disease underwent a complete resection of the primary tumor, whereas three cases had undergone an incomplete resection of the tumor. Regarding the initial chemotherapy, three cases received mild chemotherapy, two cases received no chemotherapy, and one case had high-dose multidrug chemotherapy. Regarding biologic prognostic factors, four of six cases with recurring disease had one or more unfavorable factors, whereas two cases had no unfavorable factors. Regarding the outcome after recurrence, four cases are CR, one case has a stable residual tumor, and one case died of disease with N-myc amplification.

CONCLUSIONS

Most neuroblastomas detected by mass screening at 6 months of age have biologically favorable factors. However, approximately 10% of the cases had one or more unfavorable factors and thus might have a higher risk of recurrence than the patients with no unfavorable factors. Conversely, some cases with recurring disease had no unfavorable factors; however, the reason for this is still unclear. A long-term follow-up for mass screening cases is important, and it also might be necessary to research the established biologic factors and identify other new prognostic factors.

A functional role for ERK in gene induction, but not in neurite outgrowth in differentiating neuroblastoma cells

The human neuroblastoma cell line SH-SY5Y can differentiate into a functional sympathetic neuronal phenotype when treated with low concentrations of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in the presence of serum or defined growth factors. When TrkA is introduced into the cells, NGF also induces differentiation. In both cases, protein kinase C (PKC) is pivotal for induction and maintenance of the differentiated phenotype. We have recently shown that PKC activity is needed to enable the MAPK ERK to accumulate in the nucleus of SH-SY5Y cells and hence activate transcription. To find out whether this could be one reason for the PKC dependency in the differentiation process we have investigated the role of ERK during neuronal differentiation of these cells. The results show that ERK was needed for full upregulation of the neuronal marker genes NPY and GAP-43. However, ERK activity was not necessary for TPA-induced neurite formation. Neither was activation of ERK sufficient to promote neurite outgrowth. The results clearly show that there was no correlation between nuclear ERK activity, measured as SRE transactivation, and neurite formation in TPA-differentiated SH-SY5Y neuroblastoma cells.

Signal transduction pathways through TRK-A and TRK-B receptors in human neuroblastoma cells

Little is known about the signal transduction pathways of TRK family receptors in neuroblastoma (NB) cells. In this study, an NB cell line, designated MP-N-TS, was established from an adrenal tumor taken from a 2-year-old boy. This cell line expressed both TRK-A and TRK-B receptors, which is rare in a single NB cell line. Therefore, the MP-N-TS cell line was used to determine whether the signal transduction through these constitutive receptors is functional. Three neurotrophins, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-4 / 5 (NT-4 / 5), induced tyrosine phosphorylation of panTRK, and BDNF and NT-4 / 5 induced tyrosine phosphorylation of TRK-B. Tyrosine phosphorylation of panTRK and / or TRK-B by the neurotrophins was inhibited in the presence of a tyrosine kinase inhibitor K252a. Tyrosine phosphorylation of Src homologous and collagen (Shc), extracellular signal-regulated kinase (ERK)-1 and ERK-2, and phospholipase C-gamma1 (PLC-gamma1) was increased by the three neurotrophins and the increase was inhibited in the presence of K252a. Activation of Ras, detected as the GTP-bound form of Ras, was induced by the three neurotrophins. The neurotrophins did not modulate the expressions of TRK-A or TRK-B mRNA, but they did induce the expression of c-fos mRNA. Exogenous NGF induced weak neurite outgrowth, whereas exogenous BDNF and NT-4 / 5 induced distinct neurite outgrowth. Exogenous BDNF and NT-4 / 5 increased the number of viable cells, while NGF did not. Our results demonstrate that the signal transduction pathways through TRK-A and TRK-B in MP-N-TS cells are functional and similar, and the main downstream signaling pathways from the three neurotrophins are mitogen-activated protein kinase (MAPK) cascades through Shc, activated Ras, ERK-1 and ERK-2, and the transduction pathway through PLC-gamma1. Further, BDNF and NT-4 / 5 increased cell viability. The MP-N-TS cell line should be useful for clarifying the TRK-A and TRK-B signaling pathways responsible for the different prognoses in patients with NB.

Risk of unfavorable character among neuroblastomas detected through mass screening. The Japanese Infantile Neuroblastoma Cooperative Study

Current study shows that about 50% of neuroblastomas (NBs) detected through mass screening had factor(s) indicating an unfavorable biological nature and that early intervention after the screening might improve clinical outcome of the patients. On the other hand, favorable properties were detected in the remaining half of the mass-screening NBs. Some of them might have the ability to regress spontaneously. Therapeutic modality should be determined according to their biological nature. Further investigation for their biologic properties is necessary to evaluate the benefits of the mass screening.

Nerve growth factor (NGF) influences differentiation and proliferation of myogenic cells in vitro via TrKA

Classic studies have established that muscle cells exert trophic actions on neurons of the developing peripheral nervous system through the production of neurotrophins. For this reason neurotrophins are also known as 'target-derived factors'. During differentiation, muscle cells also express some neurotrophin receptors, such as the low-affinity p75 neurotrophin receptor, which binds all neurotrophins, and the high affinity tyrosine kinase receptor TrKA, nerve growth factor (NGF) transducing receptor. The functional roles of these receptors in muscle cells are still unclear and only fragmentary and controversial data are available regarding the responsiveness of muscle cells to NGF. The aim of the present study is to investigate the effects of NGF on cells of myogenic lineage. The rat myogenic cell line L6, primary cultures of adult human myoblasts, and the human rhabdomyosarcoma cell line TE-671 were used in this study. As expected, all the three cell types expressed NGF, p75 and TrKA. NGF was expressed by L6 and primary myoblasts following differentiation, but it was constitutively expressed at high levels in the TE-671 rhabdomyosarcoma cells. In L6 myoblasts, p75 receptor was expressed in myoblasts but not in myotubes early after plating; while some primary human myoblasts expressed it at all the time-points tested. Some fusiform cells of the TE-671 rhabdomyosarcoma cell line also expressed p75. TrKA was constitutively immunodetected in all the three cell lines, suggesting that these cells may respond to NGF. Addition of exogenous NGF increased the fusion rate of both primary and L6 myoblasts, as well as the proliferation of the slowly dividing primary myoblasts. Consistently, blocking the action of endogenously produced NGF with a specific neutralizing antibody decreased the percentage of fusion in both primary and L6 myoblasts. On the contrary, blocking the binding of NGF to p75 did not affect the percentage of fusion. Furthermore, neither exogenous NGF nor NGF- or p75-neutralizing antibodies appeared to affect the rhabdomyosarcoma cells, which have a high proliferation rate and do not fuse. Pharmacological inhibition of TrKA signal transduction with K252a (in the nM range) and tyrphostin AG879 (in the low microM range) resulted in a dramatic dose-dependent decrease in proliferation of all of the myogenic cell lines tested. Interestingly, this was especially evident in the rapidly dividing rhabdomyosarcoma cell line. The TrKA inhibitors also blocked fusion of L6 and primary myoblasts and induced morphological changes characterized by the flattening of the cells and a 'spider-like' rearrangement of the intermediate filaments in all three cell lines with some minor differences. A transfection study showed that p75-overexpressing L6 cells do not fuse and present changes in their morphology similar to the TrKA-inhibitors treated L6 cells. These data support the notion that NGF expression in skeletal muscle is not only associated with a classical target-derived neurotrophic function for peripheral nervous system neurons, but also with an autocrine action which affects the proliferation, fusion into myotubes, and cell morphology of developing myoblasts. The present data also suggest that these effects of NGF are mediated by TrKA receptors and that a sustained presence of NGF is needed for increase fusion into myotubes. Lastly, the dramatic anti-proliferative effect of TrKA inhibitors on myogenic cells, and especially on the TE-671 rhabdomyosarcoma cell line, suggests that pharmacological interference with NGF signal transduction could be effective in the control of these malignancies.

Activation and protein kinase C-dependent nuclear accumulation of ERK in differentiating human neuroblastoma cells

The human neuroblastoma cell line SH-SY5Y is a well characterized model for sympathetic neuronal differentiation in vitro. Several differentiation protocols exist, one of which, the addition of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in the presence of serum, has been thoroughly studied. Wild-type SH-SY5Y cells are unresponsive to nerve growth factor (NGF), but cells transfected with the high-affinity NGF receptor TrkA (SH-SY5Y/TrkA) differentiate in response to NGF. In the present study, we have addressed the existence of a differentiation-specific mode of activation and subcellular distribution of the extracellular signal-regulated kinases ERK1 and ERK2 in SH-SY5Y/wt and SH-SY5Y/TrkA. Both TPA and NGF induced a sustained activation and nuclear accumulation of ERK that was accompanied by transactivation of a serum response element (SRE)-driven reporter and of the c-fos gene. However, activation and nuclear accumulation of ERK were not sufficient to induce neuronal differentiation in SH-SY5Y, as demonstrated by the response to TPA in serum-free cultures. Nuclear accumulation but not activation of ERK was demonstrated to require active protein kinase C (PKC). The effect of specific PKC inhibitors on subcellular distribution of ERK and ERK-dependent transcription suggests a functional role for PKC in the regulation of nuclear ERK activity in SH-SY5Y neuroblastoma cells.

MYC oncogenes and human neoplastic disease

c-myc, N-myc and L-myc are the three members of the myc oncoprotein family whose role in the pathogenesis of many human neoplastic diseases has received wide empirical support. In this review, we first summarize data, derived mainly from non-clinical studies, indicating that these oncoproteins actually serve quite different roles in vivo. This concept necessarily lies at the heart of the basis for the observation that the deregulated expression of each MYC gene is reproducibly associated with only certain naturally occurring malignancies in humans and that these genes are not interchangeable with respect to their aberrant functional consequences. We also review evidence implicating each of the above MYC genes in specific neoplastic diseases and have attempted to identify unresolved questions which deserve further basic or clinical investigation. We have made every attempt to review those diseases for which significant and confirmatory evidence, based on studies with primary tumor material, exists to implicate MYC members in their causation and/or progression.

The position and size of radiological nephrogram in Japanese preschool children

The early detection of retroperitoneal masses in children, such as neuroblastoma, Wilm's tumor, hydronephrosis and cystic renal diseases, has a great clinical importance for the improvement of their prognosis. The kidney is often affected in its size or position by these lesions, and occasionally allows clinicians to find a clue to reach the correct diagnosis before the patient become symptomatic. Since we had no clinically available nomogram on the position and the size of the kidney in Japanese children, we measured the size and position of the kidneys on plain abdominal x-rays in 347 Japanese children in preschool years with a special attention to their relationship with the spine. As a result, the nomogram showed age dependent growth of the kidneys keeping almost the same ratio with the spine, while the distance between the upper pole of the kidney and the spine remained less than 10 mm in all age groups. Our nomogram may be useful not only for picking up the malposition of the kidneys but also for the follow up of the patients with chronic renal diseases affecting the growth of the kidneys.