Patient-derived organoids (PDOs) as a novel in vitro model for neuroblastoma tumours

BACKGROUND

Neuroblastoma (NB) is a paediatric tumour of the sympathetic nervous system. Half of all cases are defined high-risk with an overall survival less than 40% at 5 years from diagnosis. The lack of in vitro models able to recapitulate the intrinsic heterogeneity of primary NB tumours has hindered progress in understanding disease pathogenesis and therapy response.

METHODS

Here we describe the establishment of 6 patient-derived organoids (PDOs) from cells of NB tumour biopsies capable of self-organising in a structure resembling the tissue of origin.

RESULTS

PDOs recapitulate the histological architecture typical of the NB tumour. Moreover, PDOs expressed NB specific markers such as neural cell adhesion molecules, NB84 antigen, synaptophysin (SYP), chromogranin A (CHGA) and neural cell adhesion molecule NCAM (CD56). Analyses of whole genome genotyping array revealed that PDOs maintained patient-specific chromosomal aberrations such as MYCN amplification, deletion of 1p and gain of chromosome 17q. Furthermore, the PDOs showed stemness features and retained cellular heterogeneity reflecting the high heterogeneity of NB tumours.

CONCLUSIONS

We were able to create a novel preclinical model for NB exhibiting self-renewal property and allowing to obtain a reservoir of NB patients' biological material useful for the study of NB molecular pathogenesis and to test drugs for personalised treatments.

Influence of segmental chromosome abnormalities on survival in children over the age of 12 months with unresectable localised peripheral neuroblastic tumours without MYCN amplification

Background:

The prognostic impact of segmental chromosome alterations (SCAs) in children older than 1 year, diagnosed with localised unresectable neuroblastoma (NB) without MYCN amplification enrolled in the European Unresectable Neuroblastoma (EUNB) protocol is still to be clarified, while, for other group of patients, the presence of SCAs is associated with poor prognosis.

Methods:

To understand the role of SCAs we performed multilocus/pangenomic analysis of 98 tumour samples from patients enrolled in the EUNB protocol.

Results:

Age at diagnosis was categorised into two groups using 18 months as the age cutoff. Significant difference in the presence of SCAs was seen in tumours of patients between 12 and 18 months and over 18 months of age at diagnosis, respectively (P=0.04). A significant correlation (P=0.03) was observed between number of SCAs per tumour and age. Event-free (EFS) and overall survival (OS) were calculated in both age groups, according to both the presence and number of SCAs. In older patients, a poorer survival was associated with the presence of SCAs (EFS=46% vs 75%, P=0.023; OS=66.8% vs 100%, P=0.003). Moreover, OS of older patients inversely correlated with number of SCAs (P=0.002). Finally, SCAs provided additional prognostic information beyond histoprognosis, as their presence was associated with poorer OS in patients over 18 months with unfavourable International Neuroblastoma Pathology Classification (INPC) histopathology (P=0.018).

Conclusions:

The presence of SCAs is a negative prognostic marker that impairs outcome of patients over the age of 18 months with localised unresectable NB without MYCN amplification, especially when more than one SCA is present. Moreover, in older patients with unfavourable INPC tumour histoprognosis, the presence of SCAs significantly affects OS.

Segmental chromosomal alterations have prognostic impact in neuroblastoma: a report from the INRG project

Background:

In the INRG dataset, the hypothesis that any segmental chromosomal alteration might be of prognostic impact in neuroblastoma without MYCN amplification (MNA) was tested.

Methods:

The presence of any segmental chromosomal alteration (chromosome 1p deletion, 11q deletion and/or chromosome 17q gain) defined a segmental genomic profile. Only tumours with a confirmed unaltered status for all three chromosome arms were considered as having no segmental chromosomal alterations.

Results:

Among the 8800 patients in the INRG database, a genomic type could be attributed for 505 patients without MNA: 397 cases had a segmental genomic type, whereas 108 cases had an absence of any segmental alteration. A segmental genomic type was more frequent in patients >18 months and in stage 4 disease (P<0.0001). In univariate analysis, 11q deletion, 17q gain and a segmental genomic type were associated with a poorer event-free survival (EFS) (P<0.0001, P=0.0002 and P<0.0001, respectively). In multivariate analysis modelling EFS, the parameters age, stage and a segmental genomic type were retained in the model, whereas the individual genetic markers were not (P<0.0001 and RR=2.56; P=0.0002 and RR=1.8; P=0.01 and RR=1.7, respectively).

Conclusion:

A segmental genomic profile, rather than the single genetic markers, adds prognostic information to the clinical markers age and stage in neuroblastoma patients without MNA, underlining the importance of pangenomic studies.

Genomic aberrations in normal appearing mucosa fields distal from oral potentially malignant lesions

OBJECTIVES

Oral fields of visually normal and non-dysplastic mucosa (ODFs) may represent the precursors of oral potentially malignant lesions (OPMLs). Aim of the study was to provide new evidence for the concept of the "field carcinogenesis" model by comparing the ODF and OPML genomic aberration profiles obtained by high resolution DNA flow cytometry (hr DNA-FCM) and array-Comparative Genomic Hybridization (a-CGH). A second aim was to investigate if specific CGH aberrations were associated with DNA aneuploidy.

METHODS

Nineteen patients with single OPMLs were recruited for the study. In parallel with obtaining samples of OPML tissue from 11 leukoplakias without dysplasia (nd-OPMLs) and 8 with dysplasia (d-OPMLs), we also obtained samples from distant ODFs. DNA aneuploid nuclei detected by hr DNA-FCM were physically separated, based on DNA content, from the DNA diploid components with a DNA-FCM-Sorter. These relatively pure subpopulations of epithelial nuclei were then submitted to DNA extraction and a-CGH for a genome-wide analysis of DNA copy number aberrations (CNAs).

RESULTS

The frequencies of DNA aneuploidy (DI ≠ 1) among ODFs and OPMLs were respectively 5.3% and 32%. The DI aneuploid values of ODFs and nd-OPMLs were all near-diploid (DI ≠ 1 and DI ≤ 1.4), while for d-OPMLs were high-aneuploid (DI > 1.4) in 40% of the cases. CNA averages were 1.9 in ODFs and 6.5 in OPMLs. The gain of the chromosomal region 20q13.33-qter was observed in 37% of both ODFs and corresponding OPMLs. Additional common regions included 7p22.2-pter, 11p15.5-pter and 16p13.3-pter where gains were observed. Furthermore, gains of 20q13.31-q13.33 and of 5p13.33-pter and loss of 9p21.3 were detected at high frequency (respectively, at 62.5%, 50% and 50%) only in d-OPMLs. In particular, loss at 9p21.3, gain at 5p13.33-pter and gain of 20q13.31-q13.33 were associated with DNA aneuploidy (p = 0.00004; p = 0.0005; p = 0.01).

CONCLUSIONS

ODFs and OPMLs showed common CNAs in specific chromosomal regions suggesting that they may represent early events of the natural history of oral carcinogenesis according to the field effect cancerization and may contribute to the ODF-OPML transition. In addition, loss at 9p21.3 and gains at 5p13.33-pter and 20q13.31-q13.33 may contribute to DNA aneuploidization.

Electrical characterization of DNA-functionalized solid state nanopores for bio-sensing

We present data concerning the electrical properties of a class of biosensor devices based on bio-functionalized solid state nanopores able to detect different kinds of interactions between probe molecules, chemically attached to the pore surface, and target molecules present in solution and electrophoretically drawn through the nanometric channel. The great potentiality of this approach resides in the fact that the functionalization of a quite large pore (up to 50-60 nm) allows a sufficient diameter reduction for the attainment of a single molecule sensing dimension and selective activation, without the need for further material deposition, such as metal or oxides, or localized surface modification. The results indicate that it will be possible, in the near future, to conceive and design devices for parallel analysis of biological samples made of arrays of nanopores differently functionalized, fabricated by standard lithographic techniques, with important applications in the field of molecular diagnosis.

DNA-functionalized solid state nanopore for biosensing

The possible use of nanopores for single DNA molecules biosensing has been demonstrated, but much remains to do in order to develop advanced engineered devices with enhanced stability, and controlled geometry and surface properties. Here we present morphological and electrical characterization of solid state silicon nitride nanopores fabricated by focused ion beam direct milling and chemically functionalized by probe oligonucleotides, with the final aim of developing a versatile tool for biosensing and gene expression profiling.

PHOX2A and PHOX2B genes are highly co-expressed in human neuroblastoma

The detection of PHOX2B mutations in a small proportion of patients affected with either familial or sporadic neuroblastoma (NB), has arisen interest on the possible pathogenic role of this gene in the disease determination. In this light, we have carried out a quantitative expression analysis of PHOX2B and its paralogue PHOX2A on a panel of NB cell lines and NB tumour samples to identify a possible differential expression between NB cells and their normal counterpart (adrenal medulla cells). Our results revealed that both PHOX2A and PHOX2B are over-expressed in tumour samples and NB cell lines. Particularly, the expression levels of the two genes in NB cell lines show a highly significant correlation, suggesting their possible synergistic role or a coordinated expression regulation. Furthermore, PHOX2 gene over-expression in NB tumours and cell lines suggests these genes may be widely involved in NB development through either a direct mechanism of up-regulation or a failure in maintaining proper transcript levels after embryonic development.

Proliferation-associated Brn-3b transcription factor can activate cyclin D1 expression in neuroblastoma and breast cancer cells

Brn-3b transcription factor enhances proliferation of neuroblastoma (NB) and breast cancer cell lines in vitro and increases the rate and size of in vivo tumour growth, whereas reducing Brn-3b slows growth, both in vitro and in vivo. Brn-3b is elevated in >65% of breast cancer biopsies, and here we demonstrate that Brn-3b is also elevated in NB tumours. We show a significant correlation between Brn-3b and cyclin D1 (CD1) in breast cancers and NB tumours and cell lines. Brn-3b directly transactivates the CD1 promoter in co-transfection experiments, whereas electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrate that Brn-3b protein binds to an octamer sequence located in the proximal CD1 promoter. Site-directed mutagenesis of this sequence resulted in loss of transactivation of the CD1 promoter by Brn-3b. Thus, Brn-3b may act to alter growth properties of breast cancer and NB cells by enhancing CD1 expression in these cells.

Biological and clinical role of p73 in neuroblastoma

The p73 gene is a p53 homologue localized at 1p36.3, a chromosomal region frequently deleted in neuroblastoma. p73 was originally considered an oncosuppressor gene. However, it was soon realized that its mode of action did not resemble that of a classic anti-oncogene. The recent discovery of N-terminal truncated isoforms, with oncogenic properties, showed that p73 has a 'two in one' structure. Indeed, the full-length variants are strong inducers of apoptosis while the truncated isoforms inhibit the pro-apoptotic activity of p53 and of the full-length p73. This review summarizes some aspects of p73 biology with particular reference to its possible role in neuroblastoma.

Quality assessment of genetic markers used for therapy stratification

PURPOSE

Therapy stratification based on genetic markers is becoming increasingly important, which makes commitment to the highest possible reliability of the involved markers mandatory. In neuroblastic tumors, amplification of the MYCN gene is an unequivocal marker that indicates aggressive tumor behavior and is consequently used for therapy stratification. To guarantee reliable and standardized quality of genetic features, a quality-assessment study was initiated by the European Neuroblastoma Quality Assessment (ENQUA; connected to International Society of Pediatric Oncology) Group.

MATERIALS AND METHODS

One hundred thirty-seven coded specimens from 17 tumors were analyzed in 11 European national/regional reference laboratories using molecular techniques, in situ hybridization, and flow and image cytometry. Tumor samples with divergent results were re-evaluated.

RESULTS

Three hundred fifty-two investigations were performed, which resulted in 23 divergent findings, 17 of which were judged as errors after re-evaluation. MYCN analyses determined by Southern blot and in situ hybridization led to 3.7% and 4% of errors, respectively. Tumor cell content was not indicated in 32% of the samples, and 11% of seemingly correct MYCN results were based on the investigation of normal cells (eg, Schwann cells). Thirty-eight investigations were considered nonassessable.

CONCLUSION

This study demonstrated the importance of revealing the difficulties and limitations for each technique and problems in interpreting results, which are crucial for therapeutic decisions. Moreover, it led to the formulation of guidelines that are applicable to all kinds of tumors and that contain the standardization of techniques, including the exact determination of the tumor cell content. Finally, the group has developed a common terminology for molecular-genetic results.

Localized unresectable neuroblastoma: results of treatment based on clinical prognostic factors

BACKGROUND

We previously reported that stage 3 neuroblastoma comprises (i) a low-risk group including all infants (age 0-11 months) as well as older children with non-abdominal primaries, and (ii) a high-risk group made up of children >1 year of age with abdominal primaries. Aggressive chemotherapy was effective only in the latter group.

PATIENTS AND TREATMENT

On this basis, in 1990 we designed a new protocol by which all low-risk patients received standard-dose chemotherapy, while the high-risk ones received very aggressive chemotherapy.

RESULTS

Between November 1990 and December 1997 a total of 95 eligible and evaluable children were enrolled: 47 were low-risk (35 infants and 12>1 year of age at diagnosis and having non-abdominal primaries), and 48 were high-risk (being >1 year of age and having abdominal primaries). Of the 47 low-risk patients, five relapsed and four subsequently died. The 5-year overall survival (OS) was 91%. Of the 48 patients in the high-risk group, 22 relapsed or progressed, 18 of whom died from their disease and two from toxicity, and one was lost to follow-up. The 5-year OS was 60%. Univariate analysis showed that age, site of primary, risk-group, urine vanillylmandelic excretion, plasma levels of lactate dehydrogenase, ferritin and neurone-specific enolase, and MYCN status correlated with outcome. However, multivariate analysis showed that only MYCN status retained prognostic value.

CONCLUSIONS

In low-risk stage 3 neuroblastoma, standard-dose chemotherapy is associated with an excellent chance of being cured. Aggressive chemotherapy is effective for high-risk patients, but results are still unsatisfactory. MYCN gene amplification is a prognostic indicator for most, but not all, treatment failures.

Expression of DeltaNp73 is a molecular marker for adverse outcome in neuroblastoma patients

The p73 gene is a p53 homologue which induces apoptosis and inhibits cell proliferation. Although p73 maps at 1p36.3 and is frequently deleted in neuroblastoma (NB), it does not act as a classic oncosuppressor gene. In developing sympathetic neurons of mice, p73 is predominantly expressed as a truncated anti-apoptotic isoform (DeltaNp73), which antagonizes both p53 and the full-length p73 protein (TAp73). This suggests that p73 may be part of a complex tumor-control mechanism. To determine the role of DeltaNp73 in NB we analyzed the pattern of expression of this gene in vivo and evaluated the prognostic significance of its expression. Our results indicate that DeltaNp73 expression is associated with reduced apoptosis in a NB tumor tissue. Expression of this variant in NB patients significantly correlates with age at diagnosis and VMA urinary excretion. Moreover it is strongly associated with reduced survival (HR=7.93; P<0.001) and progression-free survival (HR=5.3; P<0.001) and its role in predicting a poorer outcome is independent from age, primary tumor site, stage and MYCN amplification (OS: HR=5.24, P=0.012; PFS: HR=4.36, P=0.005). In conclusion our data seem to indicate that DeltaNp73 is a crucial gene in neuroblastoma pathogenesis.

Exclusion of candidate genes and chromosomal regions in familial neuroblastoma

Two families with recurrence of neuroblastoma one Italian and one British with three and two affected children respectively were genotyped using polymorphic markers on chromosome 1 spanning the p32-p36 region frequently deleted in neuroblastoma tumor cells. Linkage to this region was excluded by haplotype inspection and negative lod scores. Furthermore, the exclusion of genes involved in neurocristopathies sometimes associated with neuroblastoma was carried out by typing the Italian family with polymorphic markers located in or near the corresponding genes. Finally, linkage analysis in the two families showed negative lod scores for markers spanning the 16p12-13 chromosomal region where a locus for familial neuroblastoma has been recently mapped. Our findings indicate that different genes are involved in the pathogenesis of familial neuroblastoma.

Somatostatin receptor type 2 gene expression in neuroblastoma, measured by competitive RT-PCR, is related to patient survival and to somatostatin receptor imaging by indium -111-pentetreotide

BACKGROUND

We previously reported that human neuroblastoma cell lines and primary neuroblastoma tumors expressed a variable amount of mRNA for type 2 somatostatin (sst2) receptor gene. We also found that high level of sst2 expression were positively related to patient survival.

PROCEDURE

We studied retrospectively 49 primary neuroblastomas. To detect and measure sst2 mRNA expression we developed a quantitative RT-PCR based on competitive PCR. When possible the number of MYCN copies was also measured with competitive PCR. RESULTS;. We found that the lowest level of sst2 mRNA was detected in advanced stages of neuroblastomas (stage IV) when compared with the other stages (P< 0.005). Patients with high levels of sst2 expression (>7 x 10(7) molecules/microg RNA) had a cumulative survival better than those with low sst2 expression (P < 0.0005). This predictive independent value of sst2 (P= 0.005) is retained after stratification for N-myc amplification. Finally we verified that the ex vivo sst2 gene expression in tumor samples was positively related (P < 0.01) to the in vivo semiquantitative determination of sst2 protein, assessed by 111In-pentetreotide imaging.

CONCLUSIONS

Our data indicate that the measurement of sst2 mRNA measurement could represent a relevant tool in the prediction of neuroblastoma outcome, independently from MYCN amplification.

Numerical and structural aberrations in advanced neuroblastoma tumours by CGH analysis; survival correlates with chromosome 17 status

Rapid tumour progression in neuroblastoma is associated with MYCN amplification, deletion of the short arm of chromosome 1 and gain of 17q. However, patients with advanced disease without MYCN amplification and/or 1p deletion have a very poor outcome too, which suggests other genetic defects may predict an unfavourable prognosis. We employed CGH to study 22 tumours of patients at stages 3 and 4 over one year of age (6 and 16 cases respectively). Patients were divided in groups (A) long-term survivors and (B) short-term survivors. CGH showed a total of 226 chromosome imbalances (110 in group A and 116 in group B). The neuroblastoma cells of long-term survivors showed a preponderance of numerical aberrations (54%vs 43%); particularly gains of entire chromosomes 1 (P< 0.03), 7 (P< 0.04) and 19 (P< 0.05). An extra copy of 17 was detected in 6/8 (75%) samples of group A and only 1/14 (7%) samples of group B (P< 0.002). Conversely, tumours of patients who died from disease progression displayed a higher frequency of structural abnormalities (43%vs 35%), including loss of 1p, 9p, 11q, 15q and 18q and gain of 12q, although the difference was not significant (P = 0.24). Unbalanced gain of 17q was detected in 8/14 (57%) tumours of group B and only 1/8 (13%) tumours of group A (P< 0.05). The peculiar genetic difference observed in the tumours of long and short-term survivors may have prognostic relevance.

Quantitative determination of sst2 gene expression in neuroblastoma tumor predicts patient outcome

Neuroblastoma (NB) is the most common pediatric neuroendocrine tumor, and it is characterized by a quite variable clinical course. We previously found a great variability in the expression of somatostatin receptor type 2 (sst2) in several human NB cell lines and primary tumors. In this report we investigated whether expression of sst2 is somehow related to clinical outcome. We performed a retrospective study on 54 patients with a maximum follow-up of 100 months. The concentration of specific messenger ribonucleic acid (mRNA) for sst2 was measured by competitive RT-PCR and validated, in a small subset of samples, by quantitative imaging of gene (in situ hybridization) and protein (immunohistochemistry) expression. We found that sst2 mRNA was variably expressed in all NB tumors (range, 2.5 x 10(5) to 8 x 10(9) molecules/microg RNA) with a relevant reduction in the more advanced stage (P < 0.01). Analysis of Kaplan-Meier curves indicated that sst2 expression is positively related to the overall (P < 0.0001) and event-free (P < 0.0001) survival. Expression of sst2 was negatively related to tumor stage (P < 0.02) and MYCN amplification (P < 0.001), a poor prognostic factor. However, the prognostic information derived from sst2 is apparently independent from MYCN amplification, as assessed by stratifying sst2 values according to MYCN. In addition, the expression of sst2 was the only significant prognostic factor (P < 0.02) when it was included in a multivariate model containing other well known prognostic factors such as age, stage, and MYCN amplification. Hence, we propose that sst2 expression represents a new prognostic marker for NB. The main clinical value of a quantitative measure of sst2 lies in its ability to detect patients at low risk, independently from other prognostic factor, including MYCN amplification.

Refined chromosomal localization of the putative tumor suppressor gene TP73

We report the refined chromosomal localization of the putative tumor suppressor gene TP73 (alias p73) within the genomic region between the anonymous loci D1Z2 and D1S47. The region measures less than 6 Mb and covers a genetic distance of 16 cM. The present mapping considerably restricts the previous cytogenetic localization of TP73.

Reduced expression of transforming growth factor-beta receptor type III in high stage neuroblastomas

Transforming growth factor beta (TGF-beta) is a powerful inhibitor of cell proliferation and a potent inducer of differentiation. Resistance to TGF-beta action is a characteristic of many malignancies and has been attributed to alterations of TGF-beta receptors as well as disturbance of downstream transduction pathways. To analyse the TGF-beta response in neuroblastoma, the expression of TGF-beta1 and TGF-beta type I, II and III receptor genes was investigated in 61 cancer samples by means of reverse transcription polymerase chain reaction. The specimens analysed belong to different stages, namely nine samples of stage 1, ten of stage 2, nine of stage 3 and 28 of stage 4. Moreover, five samples were of stage 4S, which represents a tumour form undergoing spontaneous regression. The results obtained show that TGF-beta1 and TGF-beta type I and II receptor genes appear to be almost equally expressed in neuroblastomas of all stages. Conversely, TGF-beta type III receptor gene expression, which is required for an efficacious TGF-beta binding and function, is strongly reduced exclusively in neuroblastomas of stages 3 and 4. These findings were directly confirmed by immunohistochemical analyses of ten neuroblastoma specimens. Our results suggest the occurrence of an altered TGF-beta response in advanced neuroblastomas which might be an important mechanism for escaping growth control and for developing invasiveness. Moreover, our findings allow the proposal of a novel mechanism, namely down-regulation of TGF-beta type III receptor gene expression, to avoid TGF-beta inhibitory activity.

p27Kip1 accumulation is associated with retinoic-induced neuroblastoma differentiation: evidence of a decreased proteasome-dependent degradation

Development of human neuroblastoma is due to an arrest in the differentiation program of neural crest sympathoadrenal progenitor cells. However, neuroblastomas, as well as their derived cell lines, maintain the potentiality of terminal differentiation. We investigated the molecular mechanisms by which retinoic acid, a molecule introduced in clinical trials for chemotherapy, induces differentiation in neuroblastoma cell lines. Our findings demonstrate that the retinoic acid-dependent growth arrest of LAN-5 neuroblastoma cell line is associated to a very large accumulation (>tenfold) of p27Kip1 protein, a cyclin-dependent kinase inhibitor; the protein binds and inhibits cyclin-dependent kinase 2, 4 and 6 activities, thus hampering pRb and p107 phosphorylation. p27Kip1 build-up was observable as an early phenomenon (12 - 24 h) after retinoic exposure and resulted in a time-dependent accumulation of high quantities of a free p27Kip1 form. Furthermore, retinoic treatment causes an increase of cyclin-dependent kinase 5 level and activity; however, immunoprecipitation studies proved the absence of interaction with p27kip1. No noticeable variation of other components of G1 phase cell cycle engine was observed. Pulse-chase experiments showed a remarkable elongation of p27Kip1 half-life in retinoic-treated LAN-5, while no enhancement of p27Kip1 gene expression and of the translational efficiency of its messenger RNA were demonstrated. In vivo degradation of p27Kip1 was sensitive to two highly specific proteasome inhibitors, LLnL and lactacystin, while the calpain inhibitor II ALLM and the cysteine protease inhibitor E64 did not modify the level of the protein. LLnL treatment caused a very rapid (2 h) build-up of the Cdk inhibitor content and the accumulation of higher molecular weight anti-p27Kip1 immunoreactive bands, which probably represent ubiquitinated forms of the protein. Finally, in vitro experiments demonstrated that extracts prepared from retinoic-treated LAN-5 cells degraded recombinant p27Kip1 at a rate remarkably slower than the untreated cells. Our results indicate that retinoic acid strongly increases p27Kip1 levels by down-regulating the ubiquitin-proteasome p27Kip1 degrading pathway.

Real-time quantitative PCR for the measurement of MYCN amplification in human neuroblastoma with the TaqMan detection system

BACKGROUND

Neuroblastoma is the most common extracranial malignant solid tumor in children under 5 years and is characterized by a wide clinical and biological heterogeneity, from spontaneously regressive forms to cancers with a rapid and fatal progression. MYCN oncogene amplification is considered the most important prognostic factor to evaluate survival and therapeutic choices in these patients.

METHODS

Here we present a new assay for rapid and accurate measurement of MYCN amplification, based on real-time quantitative PCR with the TaqMan(TM) reaction. The degree of MYCN amplification was derived from the ratio of the MYCN oncogene and the single-copy reference gene, beta-actin. The absolute abundance of these two genes in tumor sample DNA was obtained by extrapolation on external calibration curves generated with reference DNA.

RESULTS

We found a variable degree of MYCN amplification, from 2 to 29, in 26 of 49 (53%) neuroblastomas. These results were well correlated to those obtained with a competitive PCR assay in the same samples (r = 0. 987). MYCN amplification was associated mainly with advanced cancer stages, and the analysis of overall survival confirmed that the measurement of MYCN amplification is a predictor of patient outcome in neuroblastoma. Patients without MYCN amplification had a cumulative survival significantly higher than patients with low (<9; P = 0.02) and high (>/=9; P = 0.03) oncogene amplification.

CONCLUSION

The assay is rapid and reproducible and does not require any post-PCR analytical procedure.

Stage-independent expression and genetic analysis of tp73 in neuroblastoma

The tp73 gene, a tp53 homologue, has been sub-regionally mapped at 1p36.3, a chromosomal region frequently deleted in neuroblastoma. Due to its chromosomal localization and to the mono-allelic expression observed in some neuroblastoma cell lines, it was proposed that tp73 might be involved in the pathogenesis of neuroblastoma. Functional assays have demonstrated that tp73 can inhibit cell proliferation and induce apoptosis. The role of this gene in tumorigenesis, however, is still unclear. We analyzed tp73 expression in 95 sporadic neuroblastoma samples by RT-PCR and we detected the tp73 transcript in 46 cases (48.4%), without significant correlation with age, clinical stage or 3-year overall survival. A genetic polymorphism in the 2nd exon of tp73 was utilized to identify the transcribed allele in tumor-cell samples. Expression from only one of the tp73 alleles was found in 13 out of 16 heterozygous tumors, while in 3 samples both alleles were present. Genotype analysis of 73 patients and 150 controls showed a significant deviation (p = 0.0308) from the Hardy-Weinberg equilibrium for a tp73 allele only among neuroblastoma patients. The absence of correlation between tp73 expression and clinical stage, age and survival suggests that this gene does not play an essential function in the clinical course of the disease. However, the distribution of genomic tp73 alleles in patients indicates that a role of this gene in the development of neuroblastoma cannot be completely ruled out. Int. J. Cancer (Pred. Oncol.) 84:365-369, 1999.

Expression of B-myb in neuroblastoma tumors is a poor prognostic factor independent from MYCN amplification

The transcription factors of the Myb family are expressed in several tissues and play an important role in cell proliferation, differentiation, and survival In this study, the expression of A-myb, B-myb, and c-myb was investigated in a group of 64 neuroblastomas at different dinical stages by a sensitive reverse transcription-PCR tchnique and correlated with patients' survival. All of the myb genes were frequently expressed in neuroblastoma tumors. Interestingly, the expression of B-myb, which was detected in 33 cases, was associated with an increased risk of death (P = 0.027 in a univariate analysis), whereas there was no correlation with A-myb and c-myb expression. In addition, in a multivariate Cox regression analysis that included myb gene expression, MYCN status, age at diagnosis, and tumor staging, MYCN amplification and B-myb expression were independently associated to an increased risk (P < 0.01 and P = 0.015, respectively). In overall survival curves obtained by stratifying the neuroblastoma cases on the basis of MYCN status and B-myb expression, the group of patients without MYCN amplification and positive for B-myb expression had worse survival probability than that without MYCN amplification and nonexpressing B-myb (P < 0.01). In summary, these findings provide the first demonstration that B-myb expression can be a useful prognostic marker in human neuroblastoma. Moreover, B-myb expression has a prognostic value complementary to MYCN amplification and can identify a group of high-risk patients that would not be predicted on the basis of the MYCN status only.

Detection of DNA polymorphisms and point mutations of high-affinity nerve growth factor receptor (TrkA) in human neuroblastoma

We have studied nerve growth factor (NGF) receptors in 63 neuroblastoma tissues. We found DNA polymorphisms of TrkA consisting in C-->T transitions in tyrosine kinase domain at 6773, 7232 and 7301 nucleotides. Both C/T alleles were detected in tumors belonging to patients at stages 1, 2, 3 and 4 but not in 4S that expresses only the allele with C-->T. Furthermore, we detected a GT transversion resulting in a Gly-->Val substitution in a stage 4 and a stage 4S samples. We report the first evidence of TrkA polymorphism and point mutations in neuroblastoma.

Neuroblastoma in two siblings supports the role of 1p36 deletion in tumor development

Familial neuroblastoma occurs rarely. We studied a family with three children; one of them has a disseminated (stage 4) and another has a localized (stage 2) neuroblastoma. We observed subtelomeric locus D1Z2 (1p36) deletion in both tumors by using double-color fluorescence in situ hybridization. The MYNC gene was found in single copy in both tumors. Loss of heterozygosity (LOH) and restriction fragment length polymorphism analyses were performed by using DNA from frozen tumor cells and from microdissected tumor areas excised from paraffin-embedded sections. We detected somatic LOH at locus D1S468 (1p36) in a tumor-cell population with a trisomy 1 of the stage-2 patient. Neuroblastoma cells of the stage-4 patient were diploid and showed allelic loss at the following loci: D1S172, D1S80, D1S94, D1S243, D1S468, D1S214, D1S241, and D1S164. Haplotype study showed that the siblings inherited the same paternal 1p36-->pter chromosome region by homologous recombination and that, in the two tumors, arm 1p of different chromosomes of maternal origin was damaged. Our results suggest that the siblings inherited the predisposition to neuroblastoma associated with paternal 1p36 region and that tumors developed as a consequence of somatic loss of the maternal 1p36 allele.

Interstitial and large chromosome 1p deletion occurs in localized and disseminated neuroblastomas and predicts an unfavourable outcome

We studied chromosome 1p loss of heterozygosity (1p-LOH) in 53 neuroblastomas (NBs) using 15 (CA)n repeat loci, which covered a region of 90 cM. We also assessed chromosome 1p36 deletion by fluorescence in situ hybridization (FISH) on interphase nuclei. 1p-LOH was found in 19 (36%, 95% confidence interval (CI) 23-50%) NBs. We detected interstitial and large deletion in both localized and disseminated tumours and in one tumour of a patient at stage 4S. Allelic loss was frequently observed in 1p36 and 1p32 regions. In patients older than 1 year of age (53 versus 13%, P < 0.002) we detected significant chromosome 1p deletion and it was associated with MYCN amplification (P = 0.001). Overall survival (OS) analysis showed that 1p-LOH is predictive of a poor outcome (odds ratio 16.5, 95% CI 5.4-50.9%); therefore, 1p-LOH should be regarded as an additional tumour progression marker in neuroblastoma.

Structural and functional analysis of cyclin-dependent kinase inhibitor genes (CDKN2A, CDKN2B, and CDKN2C) in neuroblastoma

The status of the CDKN2A gene family, including CDKN2A, CDKN2B, and CDKN2C, was investigated in 24 cases of neuroblastoma. These genes were selected on the basis of 1) high incidence of their inactivation in several human cancers and 2) their localization on chromosomal regions (9p and 1p) frequently rearranged in neuroblastomas. Detailed molecular analyses indicated the absence of homozygous deletions and point mutations involving these genes in all investigated tumor samples. However, when loss of heterozygostity for chromosome 9p21 (the region where CDKN2A and CDKN2B are localized) was investigated, 16% of cases showed abnormalities in an area telomeric to the CDKN2A locus. To study transcriptional silencing of the CDKN2A gene, the methylation status of exon 1 was examined. In about 35% of cases, a partial methylation was evidenced. Analysis of the CDKN2A mRNA expression, however, did not show any relationship between methylation status and gene transcription. Finally, expression of the CDKN2B gene was demonstrated in all stage IV neuroblastomas, whereas none of stage I tumors expressed this gene. This finding suggests the occurrence of a correlation between CDKN2B transcription and tumor phenotype.

Restriction fragment length polymorphism analysis reveals different allele frequency and a linkage disequilibrium at locus D1S94 in neuroblastoma patients

Deletion of chromosome 1p and MYCN amplification have been reported as frequent abnormalities in human neuroblastoma. We studied loss of heterozygosity (LOH) in 50 (48 informative) Italian neuroblastoma patients by restriction fragment length polymorphisms (RFLPs) analysis using anonymous and hypervariable region (HVR) sequences. Twelve cases (25%) showed LOH at one or more loci. Locus D1S94 was the most frequently involved in LOH events (8/12) of deleted cases (66.6%). MYCN amplification was observed in 20% of patients which showed a significantly lower event-free survival probability (EFSp) (P = 0.004). We also studied the allelic distribution in the constitutional DNA of neuroblastoma patients (n = 44) and a matched group of healthy Italian subjects (n = 79) for loci D1S112 and D1S94. A significantly (P = 0.01) different allele frequency was detected for the two groups at locus D1S94, but not at D1S112. Moreover, the neuroblastoma population did not confirm the Hardy-Weinberg expectations at the former locus. This observation suggests the existence of an allelotype associated with neuroblastoma susceptibility.

Loss of heterozygosity for chromosome 1p in familial neuroblastoma

Loss of heterozygosity (LOH) and deletion of chromosome 1p are very often found in sporadic neuroblastoma. Nevertheless, very few data are available concerning 1p LOH in familial neuroblastoma. Families with recurrent neuroblastoma are rare and analysis of chromosome 1p in these families might give useful information for identifying the putative neuroblastoma suppressor gene. We used combined cytogenetic and molecular techniques to study 1p LOH in two neuroblastoma families. Family M has 2 out of 3 children with neuroblastoma and family C has 2 children, 1 of whom has neuroblastoma and type 1 neurofibromatosis (NF1). All patients of both families showed tumour cells with chromosome 1p deletion (1pdel), but only the patient from family C also had MYCN gene amplification. In all cases the deleted chromosome 1 was of maternal origin.

Evidence of apoptosis in neuroblastoma at onset and relapse. An analysis of a large series of tumors

Neuroblastoma (NB) is a tumor of pediatric age that is associated with high mortality in metastatic stages, although stage IVS patients undergo frequent spontaneous regression. Since apoptosis has been proposed as a possible cause of remission among cancer patients, we tested this hypothesis among both localized and metastatic NB and, in particular, NB metastatic stage IVS. We have assayed 36 localized and 117 metastatic neuroblastomas for evidence of internucleosomal DNA degradation and confirmed DNA fragmentation by the flow cytometric Terminal deoxynucleotidyl Transferase method, which also allowed us to measure DNA content and cell cycle phases. These techniques provided evidence of apoptosis in 18 out of 153 samples (11.8%), that were equally distributed among all stages except IVS, i.e. 11.1% in stage I (2/18), 11.1% in stage II (2/18), 13.2% in stage III (5/38), 13.4% in stage IV (9/67), and 0% in stage IVS (0/12). Tumor tissue samples collected at onset and also at relapse for the same patients showed that apoptosis may occur at relapse. In addition, cells appear to undergo apoptosis independently from N-myc amplification, cell cycle phase and DNA ploidy. In conclusion, apoptosis seems to take place with about an equal frequency for both favourable and unfavourable stages with an exception for IVS. Since DNA fragmentation remained undetected in stage IVS, we suggest that apoptosis is not a mechanism of spontaneous regression for these patients. A better basic understanding of the complex molecular mechanisms and biochemical pathways that control apoptosis in neuroblastoma appears to be necessary.

MYCN oncogene amplification in neuroblastoma is associated with worse prognosis, except in stage 4s: the Italian experience with 295 children

PURPOSE

To evaluate the prognostic role of MYCN oncogene amplification in children with neuroblastoma.

PATIENTS AND METHODS

Of 694 children (age, 0 to 15 years) with previously untreated neuroblastoma, 295 (42%) were evaluated at diagnosis for MYCN gene amplification.

RESULTS

Clinical characteristics and survival results of 295 patients studied and 399 not studied for MYCN were comparable. In 48 of 295 patients studied for MYCN (16%), the gene was amplified (> or = three gene copies). Amplification was more frequent in children older than 1 year, with abdominal tumor (18% v 7%), advanced disease, normal vanillylmandelic (VMA) urinary excretion, and high lactate dehydrogenase (LDH), ferritin, and neuron-specific enolase (NSE) serum levels. In patients studied for MYCN, the 5-year overall survival (OS) rate was higher for children aged less than 1 year (90% v 44%), with extraabdominal tumor, stage 1 or 2 versus 3 versus 4, and normal NSE, LDH, and ferritin serum levels. Patients with amplified MYCN had a worse OS (odds ratio [OR], 3.38; confidence interval [CI], 2.22 to 5.16). This association held after adjustment for other characteristics. The impact of MYCN amplification was greater in patients with favorable characteristics, in particular age (OR, 10.28 for infants; 2.08 for older children) and stage (OR, 35.3 for stage 1 to 2; 8.41 for stage 3; 1.76 for stage 4). However, of 29 children with stage 4s, all three with amplified MYCN survive. In a multivariate analysis, the prognostic role of MYCN amplification, age, and stage was confirmed, but the size of the effect of MYCN was dependent on age and stage.

CONCLUSION

MYCN amplification is associated with a worse prognosis in children with neuroblastoma at all ages and stages except 4s. This association is most pronounced in children with otherwise favorable prognostic indicators, and in these children should be considered as an indication for more intensive intervention.

Expression of MAGE-1, MAGE-3 and MART-1 genes in neuroblastoma

The human MAGE-1, MAGE-3 and MART-1 genes code for antigens that are specifically recognized by cytolytic T lymphocytes in a MHC-restricted manner. The MAGE-1 and MAGE-3 genes are expressed in tumors of different histotypes but not in normal adult tissues (with the exception of testis), while the MART-1 gene appears to be selectively expressed in melanoma. MAGE-1, MAGE-3 and MART-1 antigens may therefore constitute useful targets for specific anti-tumor immunization of cancer patients. Here we have investigated the expression of MAGE-1, MAGE-3 and MART-1 in 11 neuroblastoma (NB) cell lines and 73 NB tumor masses. MAGE-1 and MAGE-3 transcripts were detected simultaneously in 36% of the cell lines and in 16% of tumor samples. The MAGE-1 gene was never expressed alone except in one tumor. In contrast, MAGE-3 mRNA was found in approximately 40% of the NB tumor samples in the absence of MAGE-1 mRNA. No expression of the MART-1 gene was observed in any cell line or tumor sample. No correlation was found between MAGE gene expression and clinical stage, event-free survival and presence or absence of N-myc amplification.

Peculiar allelotype associated with susceptibility to neuroblastoma

Human neuroblastoma (NB) is characterized genetically by deletions of the short arm of chromosome I and by MYCN amplification. Loss of heterozygosity (LOH) has been found frequently for region 1p36. We have studied restriction fragment length polymorphisms (RFLPs) by using anonymous and hypervariable region (HVR) sequences to demonstrate LOH for 1p loci in 50 Italian neuroblastoma patients. Twelve cases (25%) showed LOH at one or more loci. Locus D1S94 was the most frequently involved (8/12 cases with deletion; 67%). MYCN amplification was observed in 20% of the patients. We also studied the allelic distribution in the constitutional DNA of neuroblastoma patients and of healthy Italian subjects for loci D1S112 and D1S94. A significantly (P = 0.01) different allele frequency was detected in the two groups at locus D1S94, but not at D1S112. Furthermore, the NB population was not in Hardy-Weinberg equilibrium at the former locus. This new observation suggests the existence of an allelotype associated with the susceptibility to neuroblastoma.

Gene expression and protein localisation of calcyclin, a calcium-binding protein of the S-100 family in fresh neuroblastomas

Calcyclin gene, a Ca(2+)-binding protein with homology to S-100, has been found to be expressed at different levels in leukaemic cells and in other tumour cells. We recently reported the expression of the gene in human neuroblastoma (NB) cell lines, and suggested a possible role of calcyclin in cell differentiation. To extend our findings, we investigated the expression of the gene in NB cells induced to differentiate by retinoic acid (RA), using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Time-course experiments employing LA-N-5 cells showed that calcyclin mRNA appeared 2 h after RA treatment, long before the cells were blocked in the G1 cell-cycle phase and before the neurite-like structures outgrew from the cell bodies. This suggests the involvement of the gene in the early phase of cell differentiation. Furthermore, we investigated mRNA expression in a series of fresh neuroblastomas. NB tumours showed a heterogeneous pattern of calcyclin expression, although calcyclin seemed to be expressed more frequently in cases with a favourable Shimada histology. We also studied the expression of the protein in formalin fixed and paraffin embedded tissues, by using a specific anticalcyclin antibody. The protein was detected in stromal cells which characterise a more mature histological type, and in nerve sheaths, whereas neuroblasts were negative. The tissue that expressed calcyclin protein showed a Schwann-like differentiation and, unlike S-100 protein, calcyclin was expressed in the perineurium.

Subcellular details of early events of differentiation induced by retinoic acid in human neuroblastoma cells detected by atomic force microscope

Atomic force microscopy (AFM) is gaining ever-increasing attention in biology as it allows us to achieve very high resolution both in air and in liquid. Recently, this technique has been employed for the observation of dynamic phenomena of cells in their culture medium. We employed this technology for comparing different morphologies, neuronal and substrate-adherent type, of cell lines of human neuroblastoma, a tumor derived from neuroectodermal tissue. The AFM image allows to confirm and enrich the information given by optical microscopes adding further details especially on the neural protrusions. Furthermore, we took advantage of the possibility to perform the observation of the cells in their culture medium for studying the neuroblastoma cell differentiation. For the first time, we detected the very early events of the outgrowth of neurite-like structures induced by retinoic acid. A time-course experiment has showed that the acid induces changes in the cellular membrane and dramatic modifications in the cytoskeleton already within 2 h.

Identification of an AP-1-like sequence in the promoter region of calcyclin, a S-100-like gene. Enhancement of binding during retinoic acid-induced neuroblastoma cell differentiation

The promoter region of genes involved in cell growth and differentiation is bound by specific transcription factors which regulate its expression. Our previous study showed that the calcyclin gene, which belongs to the large family of Ca2+-binding proteins, is differently expressed in SK-N-BE(2)C and LA-N-5 neuroblastoma cell lines. We analysed the region upstream the transcription initiation site of the gene before and during retinoic acid (RA)-induced differentiation. Gel-shift analysis showed that the -161,-135 untranslated region is bound by an AP-1-like protein both in SK-N-BE(2)C and LA-N-5 cells. Competition assay demonstrated that AP-2,AP-3 and NF1 transcription factors did not bind in the same region. Calcyclin mRNA is induced in RA-treated LA-N-5 cells and reaches maximal expression at 96 h, suggesting that its gene is involved in cell differentiation. Gel-shift analysis shows a strong signal of binding after 96 h of RA treatment. Our results indicate that RA induces an increase in the binding protein or improves its affinity for the AP-1-like region during neuronal differentiation. These preliminary data suggest that the calcyclin gene is involved in neuronal pathway differentiation and that AP-1-like binding sequence could be one of the gene regions that is under transcriptional factor control during cell differentiation.

[Oncogenes and suppressor genes in the genesis and progression of solid tumors in children]

Molecular and genetic analyses of tumor cell show that cellular oncogenes and suppressor genes are involved in neoplastic transformation. In pediatric tumors oncogenes as N-myc play an important role in the tumor progression. In retinoblastoma, neuroblastoma, Wilms' tumor, and rhabdomyosarcoma loss of heterozygosity for specific chromosome loci has been suggested to be a critical step in cancer development. Oncogene abnormalities can also be useful as a molecular tumor factor to foresee the prognosis of the disease. The present article is a review on the role of the oncogenes and suppressor genes in pediatric solid tumors.

Neuroblastoma: the result of multistep transformation?

Genetic and molecular abnormalities, in association with malignant phenotypes, have been previously demonstrated in a variety of human tumors. Although the multistep theory fits well for some cancers such as retinoblastoma and colon carcinoma, for many others it still remains to be proven. Neuroblastoma, a tumor found in pediatric patients, seems to fall into the multistep model. Nonrandom chromosome abnormalities have been found with 1p deletion, loss of heterozygosity for short arm of chromosome 1 and for chromosome 11q and 14q. Amplification of N-myc oncogene and an increased level of Ras protein have also been demonstrated. Therefore, even if it is not possible to show that these mutations happen as discrete events in their order of appearance, the multistep model seems involved in neuroblastoma development. Neuroblastoma has a peculiar aspect, however, that makes this tumor a natural model of defect of cell differentiation. In fact, there is a particular subset of metastatic tumors that show spontaneous regression. In vitro, neuroblastoma cell lines can be induced to differentiate along the neural pathway using retinoic acid. Other natural and chemical substances are also able to induce cell differentiation. During retinoic acid treatment, N-myc oncogene expression decreases and other genes are deregulated. p53 and MDR1 gene expression increases. These two different aspects, failure of cell differentiation pathway and genetic mutations, make the neuroblastoma one of the most difficult problems of modern molecular biology.

N-myc gene amplification/expression in localized stroma-rich neuroblastoma (ganglioneuroblastoma)

Using nucleic acid analysis and in situ hybridization we have demonstrated N-myc amplification and expression in two children with a localized (stages I and II) stroma-rich neuroblastoma (NB) (ganglioneuroblastoma). The phenomenon was observed in both undifferentiated and mature ganglion-like cells. The two children are alive and disease-free without any treatment after 16 and 17 months. These observations suggest that morphologic differentiation in NB in vivo is not necessarily followed by a decrease in N-myc expression. Moreover, N-myc amplification does not represent an adverse prognostic factor. In contrast with what happens in undifferentiated NB, N-myc amplification does not have an adverse effect on prognosis when occurring in localized (stages I and II), stroma-rich NB with a favorable histology.

Neuroblastoma: a multiple biological disease

Neuroblastoma (NB) is a paediatric tumour showing an appreciable variability in clinical evolution. Localised tumours (especially stage 1) can be mildly treated with good success while metastatic tumours (stage 4) are highly aggressive. This suggests a great biological diversity. In fact, molecular and genetic studies have revealed distinct abnormalities in localised and non-localised tumours. Loss of heterozygosity for the short arm of chromosome 1, 1p deletion, and MYCN amplification are present in stages 3 and 4 but rarely in stages 1 and 2. Metastatic stage 4S in infants is peculiar and does not show the same genetic and molecular abnormalities found in advanced metastatic tumours. Considering the biological alterations associated with NB, it would appear that advanced stage NB conforms to the multistep model of tumour development while stage 4S can be divided into two groups: one arising from a lack of cellular differentiation and the other as a consequence of an additional 'one hit' mutation.

An oligomer complementary to the 5' end region of MDR1 gene decreases resistance to doxorubicin of human adenocarcinoma-resistant cells

Acquired resistance to doxorubicin and other anti-cancer drugs is generally dependent on gene amplification of a specific nucleotide sequence, the MDR1 gene. Verapamil, cyclosporin and other drugs have been used to circumvent the resistance in experimental models in vitro and/or in vivo. We have attempted to reverse the MDR phenotype by treating human adenocarcinoma resistant cells with 20 mers of synthetic unmodified oligodeoxynucleotide MDR1 antisenses. Five ODNs towards different mRNA regions and three different schedules of ODN antisense administration were tested. We found that FCS concentration greatly influenced the stability of ODN, whereas heat-inactivated FCS had no effect. The kinetics of ODN cellular uptake suggest the presence of a saturable receptor. Among the five antisense ODNs used, the most efficient was the oligomer (ODN-1) complementary to 20 bases upstream of the AUG initiation codon. No effect was observed with antisense complementary to the nucleotide binding sites. Administration of ODN-1 every 12 hr for 72 hr partially reversed the MDR phenotype. Approximately 60% of the cells lost their resistance to doxorubicin and did not form colonies in the presence of the drug. The MDR1 mRNA was transiently down-regulated so that the level of gp170 was slightly reduced. The incomplete switch off of MDR1 gene expression may be ascribed to the large abundance and great stability of MDR1 messenger RNA. Moreover, the inactivity of the two ODNs complementary to the NBS protein domains suggests that translation inhibition is ineffective. It is likely that ODN-4 and ODN-5 complement a large number of mRNAs competing for duplex formation, because these sequences are highly conserved among many proteins.

Expression of histone H3 cell cycle-related gene, vimentin and MYC genes in pediatric brain tumors. A preliminary analysis showing the different malignant cell growth potential

Eleven pediatric brain tumors were studied for the histone H3, Vimentin and MYC gene expression. H3, an S phase cell cycle-related gene (ccr), was found prevalently expressed in tumors with a high mitotic index (MI). Vimentin gene, which contributes to maintaining the cell structure but is also demonstrated to be an early responder gene to growth stimulation was found variously expressed. The different expression of Vimentin gene in the examined samples suggests the active proliferation of the tumor cells. Analysis of MYC gene expression was found increased only in a mesenchymal chondrosarcoma while in other samples MYC mRNA was undetectable. Medulloblastoma, chondrosarcoma, and choroid plexus carcinoma have high S phase H3 gene expression associated with a high MI. Differently an astrocytoma shows a low MI associated with high H3 gene expression. This first preliminary report of H3, Vimentin and MYC gene expression in brain tumors demonstrates that malignant cells are characterized by a different gene expression and different growth potentials.