p53 protein overexpression identifies a group of central primitive neuroectodermal tumours with poor prognosis

Regulation of Chemosensitivity in Human Medulloblastoma Cells by p53 and the PI3 Kinase Signaling Pathway

In medulloblastoma, p53 expression has been associated with chemoresistance and radiation resistance and with poor long-term outcomes in the p53-mutated sonic hedgehog, MYC-p53, and p53-positive medulloblastoma subgroups. We previously established a direct role for p53 in supporting drug resistance in medulloblastoma cells with high basal protein expression levels (D556 and DAOY). We now show that p53 genetic suppression in medulloblastoma cells with low basal p53 protein expression levels (D283 and UW228) significantly reduced drug responsiveness, suggesting opposing roles for low p53 protein expression levels. Mechanistically, the enhanced cell death by p53 knockdown in high-p53 cells was associated with an induction of mTOR/PI3K signaling. Both mTOR inhibition and p110α/PIK3CA induction confirmed these findings, which abrogated or accentuated the enhanced chemosensitivity response in D556 cells respectively while converse was seen in D283 cells. Co-treatment with G-actin-sequestering peptide, thymosin β4 (Tβ4), induced p-AKT^S473 in both p53-high and p53-low cells, enhancing chemosensitivity in D556 cells while enhancing chemoresistance in D283 and UW228 cells. IMPLICATIONS: Collectively, we identified an unexpected role for the PI3K signaling in enhancing cell death in medulloblastoma cells with high basal p53 expression. These studies indicate that levels of p53 immunopositivity may serve as a diagnostic marker of chemotherapy resistance and for defining therapeutic targeting.

Atypical Teratoid/Rhabdoid Tumor: Revisiting Histomorphology and Immunohistochemistry With Analysis of Cyclin D1 Overexpression and MYC Amplification

Objectives. Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignant pediatric brain tumor, characterized by inactivation of INI1/hSNF5 gene and loss of its protein. We studied the histomorphological and immunohistochemical spectrum of this tumor including cyclin D1 expression and MYC gene amplification. Methods. Cases with INI1 loss by immunohistochemistry (IHC; from 2005 to 2018) were retrieved, reviewed, and evaluated for cyclin D1 expression by additional IHC and fluorescence in situ hybridization for MYC genes. Results. A total of 66 cases were identified. Age ranged from 1 to 20 years (≤3 years, 44 cases; >3 years, 22). Male to female ratio was 1.7:1. Tumor locations were as follows: posterior fossa: 30; supratentorial: 31; spinal: 5. AT/RT in patient ≤3 years was frequently located in the posterior fossa, composed of primitive embryonal morphology (P = .02), rarely had ample rhabdoid cells (P = .05), and had a negative impact on overall survival (P = .04). The rhabdoid cells was a conspicuous component of posterior fossa tumors compared with the supratentorial ones (P = .06). The supratentorial tumors (P = .06), absence of rhabdoid cells (P = .06), and the presence of immunological divergent differentiation (P = .11) had a comparatively better outcome. Cyclin D1 overexpression (n = 46) was noted in 32 cases and was frequently seen in the posterior fossa tumors (P = .02). CMYC (n = 42) amplification was seen in 1 case and the NMYC (n = 42) amplification in none. Conclusion. AT/RT can occur in the noninfantile age group, at nonconventional sites and frequently overexpress cyclin D1. The MYC alterations are almost nonexistent in AT/RT.

P53 and Ki-67 Expression in Primary Pediatric Brain Tumors: Does it Correlate with Presentation, Histological Grade, and Outcome?

Context:

Pediatric brain tumors are a vexing problem for the neurosurgeon due to the fragile patient cohort. We attempt to find parameters which can help us to treat and prognosticate these patients in a better way.

Aims:

This study aims to correlate clinical presentation, outcome, and histological grade with P53 and Ki-67 expression in primary pediatric brain tumors.

Setting Design:

This was a prospective, observational study.

Patients and Methods:

Forty-seven patients with primary brain tumors in the age group 0–18 years were included in this study. Clinical presentation was noted. Patients were operated, and specimen was sent for histopathological and immunohistochemistry examination for p53 and Ki-67. The WHO classification of 2007 was used to grade the tumors. Follow-up was done at 3 and 6 months with Glasgow outcome score. Expression of p53 and Ki-67 in different tumors was correlated with clinical presentation, tumor grade and outcome.

Analysis Method:

Statistical Package for Social Science version 17. P < 0.05 was considered statistically significant.

Results:

There was statistically significant correlation between high tumor grade and high Ki-67 levels (P = 0.000). On post hoc analysis, there was a significant difference between p53 levels in Grade 1 and Grade 4 tumors. There was statistically significant correlation between neurological deficit and higher p53 levels (P = 0.040). There was statistically significant correlation between poor outcome and higher p53 (P = 0.034) and Ki-67 (P = 0.000) levels at 3 months follow-up which continued at 6 months.

Conclusions:

From this study, we conclude that p53 and Ki-67 expression in pediatric brain tumors is associated with poor outcome and correlates with tumor grade. Moreover, p53 expression correlates with neurological deficit.

A study of histopathological spectrum and expression of Ki-67, TP53 in primary brain tumors of pediatric age group

Objectives:

The primary brain tumors are the second most common cause of death due to malignancies in children. This study was done to analyze the histological spectrum of primary brain tumors in children and also to find out the expression of p53 and Ki67 in some of the common pediatric brain tumors.

Materials and Methods:

This study was done over a period of 2.5 years. The patients were followed up until 6 months to determine the outcome. We examined H and E sections from 61 pediatric brain tumors and also performed immunohistochemical stains with p53 and Ki67 on 52 of these samples.

Results:

Of the 61 cases of pediatric brain tumors the commonest were pilocytic astrocytomas and medulloblastomas both constituting 22.9% of total cases, followed by high grade gliomas, that is, anaplastic astrocytoma and glioblastoma taken together (14.7%), diffuse astrocytomas (11.4%), ependymomas (8.1%), and oligodendrogliomas (4.9%). Other cases comprised craniopharyngiomas, astroblastomas, and gangliocytoma. The mean age of presentation was 9.3 years, male children being more commonly affected. Ki67 labeling index (LI) and p53 expression in pilocytic astrocytomas and diffuse astrocytomas were significantly lower than that of high-grade astrocytomas. However, there was no significant difference of expression of these two antigens in pilocytic astrocytomas and diffuse astrocytomas. It was found that Ki67 LI was a better marker for distinguishing between grades of astrocytoma than p53 (P=0.000 and P=0.002, respectively). The survival in cases of pilocytic astrocytomas was far better than high-grade gliomas. However, there was no significant difference in survival between pilocytic astrocytoma and diffuse infiltrating astrocytoma. There was significant positive correlation between expression of p53 and Ki67 LI in cases of medulloblastomas. Both p53 (P=0.002) and Ki67 LI (P=0.000) taken individually correlated well with survival in these cases. Also, Ki67 LI is better predictor of outcome than p53.

Conclusion:

From this study, it can be concluded that Ki67 and p53 score correlated well with the grade of astrocytoma; however, Ki67 is a better marker for differentiating between the grades of astrocytoma than p53. Also, Ki67 LI is a better prognostic factor than p53 in case of medulloblastomas.

p53 expression predicts dismal outcome for medulloblastoma patients with metastatic disease

Medulloblastoma (MB) is the most common malignant primary brain tumour in childhood. Metastatic disease (M+) at diagnosis is the most important negative prognostic clinical marker and, despite craniospinal irradiation and intensive chemotherapy, it remains one of the leading causes of treatment failure. To date, few clinical and biological data have been evaluated to obtain an additional prognostic profile for these high-risk patients. In this study, 169 patients with metastatic MB registered in the multicentre HIT2000 trial of the German Society of Pediatric Oncology and Haematology (GPOH) have been investigated to determine the importance of p53 protein expression in predicting survival. At a median follow-up of 4.1 years, 159 patients with p53-negative tumours had significantly better four-year event-free survival (EFS) and progression-free survival (PFS) (56 ± 11, 59 ± 4%) than 10 patients with p53-positive tumours (40 ± 16, 40 ± 16%; P = 0.018 for EFS, P = 0.007 for PFS, respectively). Furthermore, four-year overall survival (OS) of children with p53-negative tumours was higher than for children with p53-positive tumours (72 ± 4 vs. 35 ± 18%, P = 0.05). Three of the p53-positive MBs harbored a point mutation in the TP53 gene. p53 protein assessment by immunohistochemistry may be a useful tool for sub-stratification of metastatic high-risk MB patients.

Immunohistochemical expression of markers Ki-67, neun, synaptophysin, p53 and HER2 in medulloblastoma and its correlation with clinicopathological parameters

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. The alterations found include: presence of oncoproteins p53 and HER2, elevated mitotic index, and presence of neuronal differentiation. The aim of this study was to determine the immunohistochemical expression of markers Ki-67, NeuN, synaptophysin, HER2 and p53 in 40 MB samples and their correlation with clinicopathologic parameters and survival. In 29 patients (72.5%), >20% of cells were positive for Ki-67. Males showed greater ki-67 expression (p=0.02) and smaller survival rates (p=0.002). NeuN and synaptophysin were negative in 16 (40%) and 8 (20%) cases, respectively. P53 was positive in 18 (45%) cases, with 11 (61%) weakly positive and 7 (39%) strongly positive. HER2 was positive in 23 (57.5%) of the samples and did not show statistical association with survival (p=0.07).

Medulloblastoma: clinicopathologic evaluation of 42 pediatric cases

PURPOSE

The aim of this study was to assess the prognostic value of MIB-1 and p53 in the pediatric medulloblastoma group.

MATERIALS AND METHOD

Forty-two pediatric medulloblastoma cases diagnosed in a single institution during the past 10 years were evaluated. Follow-up data were available for 35 patients.

RESULTS

The immunoreactivity of MIB-1 ranged from 10% to 95%; p53 immunoreactivity was found in five cases. Of the 35 patients with follow-up, 34 patients received a combination of chemotherapy and radiotherapy, while one received chemotherapy alone. The follow-up period ranged from 5 to 64 months. Of the 35 patients, 21 were alive without any evidence of recurrent disease, three were alive with evidence of recurrent disease and 11 died of disease during follow-up. The mean survival for these 11 patients was 21.9+/-10.4 months. Of the 35 cases, 16 had MIB-1 value of 25% or lower and 19 had a value of 26% or more. Of the 16 cases with low MIB-1 value, six died of disease; of the 19 cases with high MIB-1 value, five died of disease. The statistical difference between MIB-1 and prognosis was not significant. Three of the 35 (8.5%) cases were found to be positive with p53 protein; no correlation was observed between p53 immunoreactivity and prognosis.

CONCLUSION

It appears that the MIB-1 value and p53 immunoreactivity have no relation with prognosis in pediatric medulloblastomas. However, it is convenient to support these findings with large series.

Heparanase expression and TrkC/p75NTR ratios in human medulloblastoma

Medulloblastoma (MB), the most devastating and common brain tumor in children, is highly invasive and extremely difficult to treat. Identifying the properties of MB tumors that cause them to invade and metastasize is therefore imperative for the development of novel treatments. We performed investigations to elucidate prognostic implications of heparanase (HPSE-1) and TrkC/p75(NTR) expression in MB using formalin-fixed, paraffin-embedded (FFPE) MB clinical specimens from children aged 1-19 years. Expressions of p75(NTR) and HPSE-1 correlated with each other (Pearson's correlation R = 0.899; P < 0.0001; R (2) = 81%; n = 14). In addition, TrkC:p75(NTR) ratios correlated with MB meningeal spread (R = 0.608; P = 0.0212; R (2) = 37%; n = 14). Secondly, using antibodies specific to TrkC and HPSE-1, we carried out immunohistochemistry (IHC) on 22 human MB tissue samples. IHC reaction scores revealed a significant expression of HPSE-1 in 76% of MB tissues from children aged 3 years and older (P = 0.0490; n = 17) while TrkC immunoreactivity was detected in 71% of these patient samples. Of note, TrkC was significantly present in 100% of MB female patients (P = 0.0313; n = 6). These studies support the role of p75(NTR) and HPSE-1 as two novel molecular determinants involved in the biology and clinical progression of MB.

Molecular biology of medulloblastoma: will it ever make a difference to clinical management?

Over the last 10 years approximately 750 children with medulloblastoma have been treated on consortia based clinical trials at an estimated cost of over 150 million US dollars. Despite this enormous effort, no meaningful molecular data has been generated that will inform the next generation of clinical studies. It is imperative that the neuro-oncology community give greater priority to studies of medulloblastoma molecular biology: unless we do this our patients will face a bleak future in which there is no accurate disease-risk stratification tool and no effective new treatments. We review some of the reasons we have failed to translate knowledge of medulloblastoma disease biology to the clinic and look forward to the next generation of clinical and molecular studies that are seeking to correct this.

Molecular genetics of supratentorial primitive neuroectodermal tumors and pineoblastoma

The supratentorial primitive neuroectodermal tumors (PNETs) are a group of highly malignant lesions primarily affecting young children. Although these tumors are histologically indistinguishable from infratentorial medulloblastoma, they often respond poorly to medulloblastoma-specific therapy. Indeed, existing molecular genetic studies indicate that supratentorial PNETs have transcriptional and cytogenetic profiles that are different from those of medullo-blastomas, thus pointing to unique biological derivation for the supratentorial PNET. Due to the rarity of these tumors and disagreement about their histopathological diagnoses, very little is known about the molecular characteristics of the supratentorial PNET. Clearly, future concerted efforts to characterize the molecular features of these rare tumors will be necessary for development of more effective supratentorial PNET treatment protocols and appropriate disease models. In this article the authors review existing molecular genetic data derived from human and mouse studies, with the aim of providing some insight into the putative histogenesis of these rare tumors and the underlying transforming pathways that drive their development. Studies of the related but distinct pineoblastoma PNET are also reviewed.

Molecular diagnostics in central nervous system tumors

Central nervous system (CNS) neoplasms can be diagnostically challenging, due to remarkably wide ranges in histologic appearance, biologic behavior, and therapeutic approach. Nevertheless, accurate diagnosis is the critical first step in providing optimal patient care. As with other oncology-based specialties, there is a rapidly expanding interest and enthusiasm for identifying and utilizing new biomarkers to enhance the day-to-day practice of surgical neuropathology. In this regard, the field is primed by recent advances in basic research, elucidating the molecular mechanisms of tumorigenesis and progression in the most common adult and pediatric brain tumors. Thus far, few have made the transition into routine clinical practice, the most notable example being 1p and 19q testing in oligodendroglial tumors. However, the field is rapidly evolving and many other biomarkers are likely to emerge as useful ancillary diagnostic, prognostic, or therapeutic aids. The goal of this article is to highlight the most common genetic alterations currently implicated in CNS tumors, focusing most on those that are either already in common use in ancillary molecular diagnostics testing or are likely to become so in the near future.

Increased p53 immunopositivity in anaplastic medulloblastoma and supratentorial PNET is not caused by JC virus

Background

p53 mutations are relatively uncommon in medulloblastoma, but abnormalities in this cell cycle pathway have been associated with anaplasia and worse clinical outcomes. We correlated p53 protein expression with pathological subtype and clinical outcome in 75 embryonal brain tumors. The presence of JC virus, which results in p53 protein accumulation, was also examined.

Methods

p53 protein levels were evaluated semi-quantitatively in 64 medulloblastomas, 3 atypical teratoid rhabdoid tumors (ATRT), and 8 supratentorial primitive neuroectodermal tumors (sPNET) using immunohistochemistry. JC viral sequences were analyzed in DNA extracted from 33 frozen medulloblastoma and PNET samples using quantitative polymerase chain reaction.

Results

p53 expression was detected in 18% of non-anaplastic medulloblastomas, 45% of anaplastic medulloblastomas, 67% of ATRT, and 88% of sPNET. The increased p53 immunoreactivity in anaplastic medulloblastoma, ATRT, and sPNET was statistically significant. Log rank analysis of clinical outcome revealed significantly shorter survival in patients with p53 immunopositive embryonal tumors. No JC virus was identified in the embryonal brain tumor samples, while an endogenous human retrovirus (ERV-3) was readily detected.

Conclusion

Immunoreactivity for p53 protein is more common in anaplastic medulloblastomas, ATRT and sPNET than in non-anaplastic tumors, and is associated with worse clinical outcomes. However, JC virus infection is not responsible for increased levels of p53 protein.

Prognosis-related histomorphological and immunohistochemical markers in central nervous system tumors of childhood and adolescence

Brain tumors account for approximately 20% of all childhood cancers, and are the leading cause of cancer morbidity and mortality among children. Although numerous demographic, clinical and therapeutic parameters have been identified over the past few years that have significant prognostic bearing for some pediatric brain tumors, predicting the clinical course and outcome among children with central nervous system tumors is still difficult. A survey of publications on prognosis-related histopathological and immunohistochemical features among pediatric brain tumors revealed 172 series, of which 91 presented statistically significant outcome-associated parameters as defined by a P value of less than 0.05. Most investigations revealing significant prognosis-related markers were performed on medulloblastomas (30 publications), ependymomas (25) and astrocytic tumors (18). In total, 16 cohorts consisted of more than 100 cases (5 on ependymomas, 3 each on medulloblastomas and astrocytic tumors). On the other hand, there were also 13 series with fewer than 20 cases (5 on medulloblastomas). Potentially prognostic histopathological markers vary among different entities and consist of assessment of necroses, mitoses, differentiation, vascular proliferation, and growth pattern, whereas immunohistochemical features include proliferation markers (Ki-67, MIB-1), expression of oncogenes/tumor suppressor genes and their proteins (TP53, c-erbB2), growth factor and hormonal receptors (VEGF, EGFR, HER2, HER4, ErbB-2), cell cycle genes (p27, p14ARF) and cell adhesion molecules, as well as factors potentially related to therapeutic resistance (DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the prognostic potential of histopathological and immunohistochemical markers that can be investigated by the practicing neuropathologist as part of the routine diagnostic workload, and scrutinizes their benefit for predicting therapy response and patient outcome among children with brain tumors.

Prognosis-Related Molecular Markers in Pediatric Central Nervous System Tumors

In the wake of recent progress in understanding the genetic pathways involved in the development of brain tumors, a major goal is to correlate molecular data with clinical outcome, survival, and response to treatment modalities. This is of particular importance among the pediatric population. Reliable prognostic factors could potentially permit a tailoring of therapy in that only patients with the most aggressive tumors would receive the most intense treatments. A survey of publications about prognosis-related molecular features among pediatric brain tumors revealed 74 series, of which 46 presented statistically significant outcome-associated parameters as defined by a p value <0.05. Most investigations revealing significant prognosis-related features were performed on medulloblastomas (34 publications), followed by astrocytic tumors (6 publications) and ependymomas (5 publications). Promising approaches and molecular markers include gene expression profiles, DNA ploidy, loss of heterozygosity and chromosomal aberrations as detected by CGH and FISH (1q, 17p, 17q), as well as oncogenes/ tumor suppressor genes and their proteins (TP53, PTEN, c-erbB2, N-myc, c-myc), growth factor and hormonal receptors (PDGFRA, VEGF, EGFR, HER2, HER4, ErbB-2, hTERT, TrkC), cell cycle genes (p27) and cell adhesion molecules, as well as factors potentially related to therapeutic resistance (multi-drug resistance, DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the predictive potential of molecular markers for clinical outcome and their influence on therapeutic decision-making among children with brain tumors.

Genetic alterations of human brain tumors as molecular prognostic factors

Despite a number of basic and clinical studies, it is still very difficult to improve the prognosis of patients with high-grade astrocytoma. However, the recent success of procarbazine, N-(2-chloroethyl)-N'-cyclohexyl-N-nitrosourea and vincristine (PCV) chemotherapy for oligodendrogliomas that have lost chromosomes 1p and 19q has encouraged the authors to evaluate the biological behavior of brain tumors by means of genetic analysis. Both the disorders of the p53/MDM2/p14(ARF) and the p16(INK4a)/RB signaling pathways have been found to play an essential role in tumorigenesis of various brain tumors. Herein, the authors summarize the genetic alterations of brain tumors by mainly focusing on two pathways that appear to affect significantly the patient prognosis.

Classifying the medulloblastoma: insights from morphology and molecular genetics

Significant advances in the treatment of the medulloblastoma (MB) have been made in the last 30 years, reducing mortality by 2-fold. Further improvements in the cure rate require an increased understanding of the biology of MBs, and this will translate into refinements in their classification. Scrutiny of the cytological variation found among MBs has recently led to the concept of the anaplastic MB, which overlaps the large-cell variant and appears to share its poor prognosis. In contrast, the MB with extensive nodularity, a distinctive nodular/desmoplastic variant occurring in infants, has a better outcome than most MBs in these young patients. Building on cytogenetic studies that have drawn attention to abnormalities on chromosome 17 in over a third of MBs, research shows non-random losses on chromosomes 8, 9, 10, 11 and 16, and gains on chromosomes 1, 7 and 9. Overexpression of ErbB2 receptors and losses on chromosome 17p have been proposed as independent indicators of aggressive behaviour, while high TrkC receptor expression indicates a favourable outcome. There is a strong association between anaplastic/large-cell tumours and MYC amplification, which has previously been linked with aggressive disease, but associations between abnormalities on chromosome 17 and anaplastic/large-cell MBs and between abnormalities in the shh/PTCH pathway and the desmoplastic variant are more controversial. Classification of the MB histopathologically and according to profiles of molecular abnormalities will help both to rationalize approaches to therapy, increasing the cure rate and reducing long-term side-effects, and to suggest novel treatments.

The molecular pathology of p53 in primitive neuroectodermal tumours of the central nervous system

One hundred and one pre-treatment primary central primitive neuroectodermal tumours were analysed for the expression of p53 protein by immunohistochemistry using the monoclonal antibody DO-7. The staining intensity was classified into four groups: strong, medium, weak and negative and strong staining intensity was associated with the poorest survival. DNA sequencing of the p53 gene was performed in 28 cases representing all four staining groups. Mutations were found in only three of the strong staining tumours suggesting that DNA mutations were not common events and that in the majority of the tumours with over-expressed p53, the protein was likely to be wild-type. Results of immunohistochemistry showed a significantly positive relationship between the expression of p53 and Bax and Bcl-2 proteins, but not Waf-1. Multivariate analyses supported the prognostic value of p53 immunostaining in central primitive neuroectodermal tumours and also of age and gender of patients.

Intense p53 staining is a valuable prognostic indicator for poor prognosis in medulloblastoma/central nervous system primitive neuroectodermal tumors

Intense p53 immunostaining may predict for a poor prognosis in central nervous system primitive neuroectodermal tumor of childhood.

BACKGROUND

Medulloblastoma is a common childhood primary brain tumor. Potential prognostic indicators for patients with local disease are age, extent of resection, and gender. However, none of these are well established. Immunohistologic staining is a potentially useful means to identify high-risk patients. The purpose of this clinical pathologic study was to investigate the prognostic significance of GFAP, synaptophysin, Ki-67, and p53 immunostaining in medulloblastoma/central nervous system primitive neuroectodermal tumors (CNS PNETs.)

MATERIALS AND METHODS

The records of 40 patients with CNS PNETs were reviewed. Their surgical specimens were immunostained for p53, glial fibrillary acidic protein (GFAP), synaptophysin, and Ki-67. The p53 specimens were scored blindly for the intensity of staining of nuclei (intense vs weak) and the quantity of cells stained. The Ki-67, GFAP, and synaptophysin specimens were analyzed for quantity of cells stained.

RESULTS

Ten patients' specimens stained intensely for the p53 protein. Eleven had weakly staining nuclei. Nineteen specimens had no staining. The patients with specimens that stained intensely had a statistically significant decreased disease free survival (P = 0.03). Mere presence or quantity of p53 nuclear staining did not correlate with disease free survival. Immunohistochemical staining for Ki-67, GFAP, and synaptophysin did not correlate with disease free survival. Clinical parameters of age, gender, and extent of resection also did not approach statistical significance for disease free survival.

CONCLUSION

Intense nuclear staining for p53 was the only variable in this clinical pathologic study that reached statistical significance for disease free survival. This suggests that intense staining for p53 may be the most important prognostic indicator for non-metastatic CNS PNETs. p53 Immunostaining with antibodies against p53 in CNS PNETs should be studied in a multi-institutional setting with larger numbers of patients.

Pediatric medulloblastoma: prognostic value of p53, bcl-2, Mib-1, and microvessel density

The aim of this study was to retrospectively assess the prognostic value of p53 and bcl-2 protein expression, cell proliferation index (Mib-1 index), and tumor microvessel density (factor VIII-related antigen) in pediatric medulloblastoma patients. Tumor specimens of 55 patients (age 2-18 years) with medulloblastoma treated with a curative intent between 1972 and 1991 were studied. Slides of paraffin embedded tissue were stained with monoclonal antibodies (mAb) and examined under high power light microscopy for the presence of immunoreactivity. Microvessel density was scored both in the area of most intense staining ('Angio-max') and in 3 additional randomly selected areas. The sum of these 4 scores was termed 'Angio-total'. 'Angio-max' and 'Angio-total' were evaluated separately by two independent investigators to assess reproducibility. None of the parameters studied, i.e. p53 or bcl-2 expression, Mib-1 index or microvessel density scores were associated with patient survival. Microvessel scores between observers were significantly but weakly correlated, with correlation coefficients (r) < 0.5 for both 'Angio-max' and 'Angio-total'. Leptomeningeal spread at diagnosis was the only independent factor associated with a poor survival (p = 0.003). There was no association of leptomeningeal metastasis with any of the biological markers tested in this study.

Clinical evidence of distinct subgroups of astrocytic tumors defined by comparative genomic hybridization

In astrocytic tumors, the relationship between genetic pathways and patients' prognoses has not been fully investigated. In our studies of astrocytic tumors using comparative genomic hybridization, the presence of 8q gain was mutually exclusive of 7p gain or amplification. In this study, 45 cases of astrocytic tumor were divided into 3 groups: those with 7p gain, cases with 8q gain, or those with neither; and their clinical course, p53, and epidermal growth factor receptor (EGFR) expressions and proliferative activity were then compared. Of the cases examined, 17 (12 glioblastomas and 5 anaplastic astrocytomas) showed 7p gain. Eleven cases (5 glioblastomas, 2 anaplastic, and 4 low-grade astrocytomas) showed 8q gain. p53 accumulation was observed more frequently in cases with 8q gain than in those with 7p gain. Astrocytic tumors with 8q gain occurred more frequently in younger patients than those with 7p gain. Kaplan-Meier survival rate analysis showed higher survival rates in patients with 8q gain than in those with 7p gain. This tendency also was observed when only patients with malignant glioma were included in the survival analysis. Our results provide evidence for distinct clinical manifestations in astrocytic tumors with 8q and 7p gain.

Prognostic value of tumor-associated antigens immunoreactivity and apoptosis in medulloblastomas. An analysis of 73 cases

Medulloblastomas (MB) are the most common central nervous system malignancies in children. Numerous publications describe efforts to identify the predictive value of various patterns of MB pathology and immunohistochemistry, but received data appear to be controversial. Seventy-three patients with cerebellar MB were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to various tumor-associated antigens. Also, apoptosis detection by the in situ end-labeling method was performed. Survival analysis was made using univariate and multivariate models. Tenascin immunoreactivity and apoptotic index (AI) > or = 1.5% were found to be closely associated with poor prognosis according to an univariate analysis (P = 0.008 and 0.003, respectively). The multivariate Cox proportional hazard model exhibited independent prognostic value for the apoptotic rate only (P = 0.023). Tumors with tenascin expression and AI > or = 1.5% significantly prevailed among MB with metastatic dissemination, whereas expression of c-erbB2 oncoprotein and epidermal growth factor receptor was found to be more typical for cases with local tumor recurrence. We came to the conclusion that tenascin immunoreactivity and AI were useful for individual MB prognosis.

Comparative genomic hybridization and histological variation in primitive neuroectodermal tumours

The objective of this study was to test the hypothesis that chromosomal imbalances in central nervous system primitive neuroectodermal tumours (PNETs) reflect site and histology. We used comparative genomic hybridization to study 37 cases of PNET, of which four were cerebral and 31 were medulloblastomas classified histologically as classic (n = 17) or nodular/desmoplastic (n = 14). Tumour immunophenotype was characterized with antibodies to neuroglial, mesenchymal and epithelial markers. Chromosomal imbalances were detected in 28 medulloblastomas (90%), and significant associations between tumour variants and genetic abnormalities were demonstrated. Aberrations suggesting isochromosome 17q were present in eight (26%) medulloblastomas, of which seven were classic variants. None of these cases, or a further six with gain of 17q, showed immunoreactivity for glial fibrillary acidic protein. Loss on 9q was found in six cases (19%), five of them nodular/desmoplastic. Loss of 22 occurred in four (13%), all classic medulloblastomas in young patients with a poor outcome and immunoreactivity for more than one epithelial or mesenchymal marker. Different patterns of imbalance were found in the cerebral PNETs. There were no abnormalities of chromosome 17, but all three cases with imbalance showed losses of 3p12.3-p14.

Non-isotopic molecular cytogenetics in neuro-oncology

The molecular genetic analysis of brain tumours has been the focus of considerable interest for a number of years. However, these studies have been largely directed towards understanding the fundamental biological processes involved in tumorigenesis and the techniques which have been used require considerable molecular biological skills. Unfortunately, there has not been the impetus to correlate basic biological studies with clinical or neuropathological features. The development of non-isotopic molecular cytogenetic in situ hybridization (ISH) techniques which can be applied to archival tumour material provides an opportunity to address a wide range of neuropathological questions at a genetic level. Identification of specific chromosomes has been made possible by the isolation of probes which recognize the highly repeated sequences present in the centromeric regions of individual chromosomes. Libraries of human chromosome-specific painting probes are also available. A range of probes which bind to the whole or part of specific single copy genes are becoming available. These can be detected with either fluorochromes with different emission colours or with enzymatic detection systems in either interphase nuclei derived from fresh, fixed and embedded tumour samples, touch preparations or smears (so-called 'interphase cytogenetics') as well as conventional metaphase spreads. Comparative genomic hybridization can be used to scan the entire genome for deletions or amplifications without any pre-existing information about the likely locations of these abnormalities or the availability of any specific DNA probes. These techniques can be used to identify aneuploidy or structural alterations in individual chromosomes and are likely to yield important information about the location of genes important in the pathogenesis of brain tumours and may also provide the basis for the refinement of diagnostic or prognostic criteria of these neoplasms.

Shedding of gangliosides by human medulloblastoma cells

Shedding of immunosuppressive gangliosides is an important characteristic of both experimental and human tumors. Using a medulloblastoma cell line, Daoy, with a very high ganglioside expression (141 +/- 13 nmol/10(8) cells) and a well-characterized ganglioside complement, we have now studied ganglioside shedding by human brain tumor cells. Shedding of gangliosides, quantified by metabolic radiolabeling, was significant (169 pmol/10(8) cells/h) and was generalized with respect to the major ganglioside carbohydrate structures (G(M2), G(M3), and G(D1a)). For each ganglioside, however, shedding was selective for ceramide structures containing shorter fatty acyl chains. Rapid and ceramide-selective shedding was confirmed in two additional human medulloblastoma cell lines, D341 Med and D283 Med (112 and 59 pmol/10(8) cells/h). Significant ganglioside shedding is therefore a common characteristic of human medulloblastoma cells and may influence the biological behavior of this tumor, in view of immunosuppressive and other biological properties of shed gangliosides.

Long-term survival in an adult metastatic renal peripheral primitive neuroectodermal tumor (PPNET) with multimodality treatment including high-dose chemotherapy

We describe a 42-year-old male patient with a primitive peripheral neuroectodermal tumor (PPNET) arising from the kidney. The patient was treated sequentially with surgery, radiotherapy, experimental cytokine treatment (rhIL-6), combination chemotherapy and consolidated in complete remission with high-dose chemotherapy, supported by autologous stem cells (AST) and hematopoietic growth factors. The patient remains in complete remission at 34+ months after AST and is surviving disease-free for five years after initial presentation. The case presented here is unusual because of the renal origin and the long remission duration and survival when compared with the usual outcome of adult metastatic PPNET. High-dose chemotherapy may have favorably influenced the outcome in this patient. The case is discussed in the context of the general treatment of metastatic PPNET.

In vitro properties of a newly established medulloblastoma cell line, MCD-1

Medulloblastomas are poorly differentiated brain tumors believed to arise from primitive pleuripotential stem cells, and tend to express mixed neuronal and glial properties. In the present study, we examined immunohistochemical and neurotransmitter phenotypic properties in a newly established medulloblastoma cell line, MCD-1. MCD-1 cells were immortal, not contact-inhibited, but did not grow in soft agar. Immunohistochemical studies showed positive staining for neurofilament protein (NF), neuron-specific enolase (NSE), synaptophysin, MAP 2, tau, NCAM 180, vimentin, and S-100 protein. The cells expressed specific uptake of glutamate, serotonin, and choline, but not GABA or dopamine. A significant increase in process extension was seen in response to agents that enhance intracellular cyclic AMP, especially 3-isobutyl-1-methylxanthine (IBMX). Process formation induced by IBMX was associated with a decrease in cell proliferation as evidenced by a reduction in numbers of cells incorporating 5-bromo-2-deoxyuridine (BrdU). No increase in process extension was observed following exposure to NGF or retinoic acid. MCD-1 cells were shown to produce transforming growth factor beta (TGF beta), and were immunopositive for mutant p53. Transfection assays with the PG13-Luc reporter plasmid, which contains a p53-responsive enhancer element and a luciferase reporter gene, suggested MCD-1 cells are deficient in wild-type p53 and do not activate p53 on treatment with the anticancer agent adriamycin. The MCD-1 cell line is suggested to represent an abnormally differentiated cell type, which has some properties consistent with a multipotent neuronal phenotype while retaining some properties of immature cells of a glial lineage. The MCD-1 cell line can be used to provide a model of a medulloblastoma cell line that is resistant to growth-controlling and anticancer agents.

P53 overexpression in head and neck carcinoma and radiotherapy results

PURPOSE

P53 gene mutations are the common genetic changes encountered in human cancers, and there is extensive evidence that the P53 status may determine tumor response to therapy. This study was carried out to investigate whether there is any correlation between accumulation (overexpression) of P53 protein and poor prognosis in patients with head and neck carcinomas treated with radical radiotherapy.

METHODS AND MATERIALS

Seventy-nine patients with head and neck carcinomas who were diagnosed and treated in 1989-90 with curative radiotherapy were studied retrospectively. Paraffin sections from archival material were studied using immunohistochemical staining (IHC) with mouse monoclonal antibodies (D0-7) to human P53 protein. Univariate and multivariate analysis of loco-regional tumor control and patient survival were performed on possible prognostic factors.

RESULTS

Forty-two (53%) patients showed positive IHC staining in their tumors. Fifty-three percent of the laryngeal, 64% of the oropharyngeal, and 43% of the oral cavity carcinomas showed P53 overexpression. All tumor specimens with vascular, lymphatic, and/or sarcolemmal invasion showed P53 overexpression. The proportion of tumor-stained nuclei was higher in the poorly differentiated than in the well and moderately differentiated tumors (p < 0.05), but there was no correlation with the patient overall or disease-free 5-year actuarial survival. There was no difference in the 5-year actuarial survival and disease-free survival between patients with P53 immunostaining in their tumors and those with no immunostaining (59% vs. 65% and 57% vs. 51%, respectively). The TNM tumor stage was the most significant prognostic factor with 5-year actuarial survival of 87% for early and 14% for late stages (p << 0.0001). There was a significant correlation between immunostaining and history of smoking (p = 0.02).

CONCLUSION

The data demonstrate that the P53 accumulation as detected by immunohistochemical staining in a group of head and neck carcinomas was not predictive of patient's poor survival or disease-free survival. Multivariate statistical analysis showed that the TNM tumor stage was the only significant prognostic factor. There was a significant association between P53 accumulation and smoking.