Histopathological prognostic factors in medulloblastoma: High expression of survivin is related to unfavourable outcome

Immunoexpression of Survivin and P53 in the Histological Subtypes of Medulloblastoma: A Cross-Sectional Observational Study

Medulloblastoma (MB) is a common malignant intracranial neoplasms in children. The treatment and prognosis of this tumor depends on histology and molecular subtypes. Survivin, implicated in various malignancies, may hold prognostic significance. We investigated survivin and p53 immunoreactivity in different histological subtypes in 20 MB cases from January 2018 to June 2021. Immunohistochemistry revealed survivin expression in 75% (15/20) of cases, with cytoplasmic (10 cases), nuclear (four cases), or combined expression (one case). p53 nuclear expression was present in 35% (7/20) of cases. Classical variant MB exhibited predominant p53 and cytoplasmic survivin expression. Given the association of survivin and p53 expression with poor prognosis, especially in the prevalent classical variant, targeted therapies may hold promise for MB treatment advancement.

Dissecting the functional significance of HSP90AB1 and other heat shock proteins in countering glioblastomas and ependymomas using omics analysis and drug prediction using virtual screening

Heat shock proteins (HSPs) are the evolutionary family of proteins that are highly conserved and present widely in various organisms and play an array of important roles and cellular functions. Currently, very few or no studies are based on the systematic analysis of the HSPs in Glioblastoma (GBMs) and ependymomas. We performed an integrated omics analysis to predict the mutual regulatory differential HSP signatures that were associated with both glioblastoma and ependymomas. Further, we explored the various common dysregulated biological processes operating in both the tumors, and were analyzed using functional enrichment, gene ontology along with the pathway analysis of the predicted HSPs. We established an interactome network of protein-protein interaction (PPIN) to identify the hub HSPs that were commonly associated with GBMs and ependymoma. To understand the mutual molecular mechanism of the HSPs in both malignancies, transcription factors, and miRNAs overlapping with both diseases were explored. Moreover, a transcription factor-miRNAs-HSPs coregulatory network was constructed along with the prediction of potential candidate drugs that were based on perturbation-induced gene expression analysis. Based on the RNA-sequencing data, HSP90AB1 was identified as the most promising target among other predicted HSPs. Finally, the ranking of the drugs was arranged based on various drug scores. In conclusion, this study gave a spotlight on the mutual targetable HSPs, biological pathways, and regulatory signatures associated with GBMs and ependymoma with an improved understanding of crosstalk involved. Additionally, the role of therapeutics was also explored against HSP90AB1. These findings could potentially be able to explain the interplay of HSP90AB1 and other HSPs within these two malignancies.

Targeting the apoptosis pathway to treat tumours of the paediatric nervous system

New, more effective therapeutics are required for the treatment of paediatric cancers. Current treatment protocols of cytotoxic treatments including chemotherapy trigger cancer-cell death by engaging the apoptosis pathway, and chemotherapy efficacy is frequently impeded by apoptosis dysregulation. Apoptosis dysregulation, through genetic or epigenetic mechanisms, is a feature of many cancer types, and contributes to reduced treatment response, disease progression and ultimately treatment resistance. Novel approaches are required to overcome dysregulated apoptosis signalling, increase the efficacy of cancer treatment and improve patient outcomes. Here, we provide an insight into current knowledge of how the apoptosis pathway is dysregulated in paediatric nervous system tumours, with a focus on TRAIL receptors, the BCL-2 proteins and the IAP family, and highlight preclinical evidence demonstrating that pharmacological manipulation of the apoptosis pathway can restore apoptosis signalling and sensitise cancer cells to treatment. Finally, we discuss the potential clinical implications of these findings.

BIRC3 and BIRC5: multi-faceted inhibitors in cancer

BACKGROUND

The evasion from apoptosis is a common strategy adopted by most tumors, and inhibitors of apoptosis proteins (IAPs) are among the most studied molecular and therapeutic targets. BIRC3 (cellular IAP2) and BIRC5 (survivin) are two of the eight members of the human IAPs family. This family is characterized by the presence of the baculoviral IAP repeat (BIR) domains, involved in protein-protein interactions. In addition to the BIR domains, IAPs also contain other important domains like the C-terminal ubiquitin-conjugating (UBC) domain, the caspase recruitment (CARD) domain and the C-terminal Ring zinc-finger (RING) domain.

MAIN BODY

BIRC3 and BIRC5 have been characterized in some solid and hematological tumors and are therapeutic targets for the family of drugs called "Smac mimetics". Many evidences point to the pro-survival and antiapoptotic role of BIRC3 in cancer cells, however, not all the data are consistent and the resulting picture is heterogeneous. For instance, BIRC3 genetic inactivation due to deletions or point mutations is consistently associated to shorter progression free survival and poor prognosis in chronic lymphocytic leukemia patients. BIRC3 inactivation has also been associated to chemoimmunotherapy resistance. On the contrary, the progression from low grade gliomas to high grade gliomas is accompanied by BIRC3 expression increase, which bears relevant prognostic consequences. Due to the relationship between BIRC3, MAP3K14 and the non-canonical NF-kB pathway, BIRC3 inactivation bears consequences also on the tumor cells relying on NF-kB pathway to survive. BIRC5, on the contrary, is commonly considered an anti-apoptotic molecule, promoting cell division and tumor progression and it is widely regarded as potential therapeutic target.

CONCLUSIONS

The present manuscript collects and reviews the most recent literature concerning the role played by BIRC3 and BIRC5 in cancer cells, providing useful information for the choice of the best therapeutic targets.

Medulloblastoma cancer stem cells: molecular signatures and therapeutic targets

Medulloblastoma (MB) is the most common malignant primary intracranial neoplasm diagnosed in childhood. Although numerous efforts have been made during the past few years to exploit novel targeted therapies for this aggressive neoplasm, there still exist substantial hitches hindering successful management of MB. Lately, progress in cancer biology has shown evidence that a subpopulation of cells within the tumour, namely cancer stem cells (CSCs), are thought to be responsible for the resistance to most chemotherapeutic agents and radiation therapy, accounting for cancer recurrence. Hence, it is crucial to identify the molecular signatures and genetic aberrations that characterise those CSCs and develop therapies that specifically target them. In this review, we aim to give an overview of the main genetic and molecular cues that depict MB-CSCs and provide a synopsis of the novel therapeutic approaches that specifically target this population of cells to attain enhanced antitumorous effects and therefore overcome resistance to therapy.

Prognostic role of survivin in patients with glioma

BACKGROUND

The aim of this study was to systematically evaluate the prognostic role of survivin in patients with glioma through performing a meta-analysis.

METHODS

PubMed, Web of Science, Cochrane Library, and EMBASE were searched for potentially eligible literature. The study characteristics and relevant data were extracted. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled to estimate the prognostic role of survivin in patients with glioma.

RESULTS

Sixteen studies with 1260 patients were included. The pooled HR of higher survivin expression for overall survival was 1.96 (95% CI, 1.57-2.45). The pooled HRs of higher survivin expression for progression- and disease-free survival were 1.62 (95% CI, 0.91-2.90) and 2.41 (95% CI, 0.98-5.90), respectively. Subgroup analyses were also performed.

CONCLUSION

Our results suggested that higher survivin expression was associated with worse overall survival in patients with glioma. The findings may assist future exploration on pathogenesis, diagnosis, anti-survivin therapy, and prognosis in glioma. However, due to the limited study number, more studies are warranted to verify our results.

Tropomyosin receptor kinase C (TrkC) expression in medulloblastoma: relation to the molecular subgroups and impact on treatment response

PURPOSE

High messenger RNA (mRNA) expression of the tropomyosin receptor kinase C gene (TrkC) has been associated with favorable survival in medulloblastoma patients. Untested is whether it plays a role through modulating the response to therapy or whether it might be a surrogate marker for a favorable molecular subgroup.

METHODS

The medulloblastoma-derived cell line DAOY was stably transfected to overexpress TrkC (clone DAOY-TrkC) and compared to a control (clone DAOY-EV, empty vector transfected). Cell viability (MTS assay) was tested after irradiation or incubation with chemotherapeutic drugs. Neuroradiologic response to postoperative chemotherapy or craniospinal irradiation (CSI) of medulloblastoma patients aged 3-21 years with postoperative residual disease treated within the consecutive trials HIT'91/HIT2000 was compared to TrkC mRNA expression in their tumor samples. Five well-characterized independent expression-profiling studies covering together 686 medulloblastoma patients were analyzed for TrkC levels according to the molecular subgroups.

RESULTS

Cell viability of DAOY-TrkC compared to DAOY-EV was not different after exposure to increasing doses of irradiation, cisplatin, etoposide, or vincristine. While TrkC mRNA expression tended to be higher in non-responders (n = 5/19) to postoperative CSI (p = 0.03, ratio 15.5, 95% CI 9-267), this was the case in responders (n = 23/43) to chemotherapy (p = 0.04, ratio 6.1, 95% CI 1.1-35), both analyzed with Mann-Whitney U test (not significant after Bonferroni adjustment). The highest TrkC mRNA levels were found in the SHH subgroup across all expression-profiling studies.

CONCLUSIONS

High TrkC mRNA expression appears to be frequent in the SHH subgroup and seems not to have a major effect on therapy responsiveness in medulloblastoma patients.

Posterior Fossa Tumors

Pediatric brain tumors are the leading cause of death from solid tumors in childhood. The most common posterior fossa tumors in children are medulloblastoma, atypical teratoid/rhabdoid tumor, cerebellar pilocytic astrocytoma, ependymoma, and brainstem glioma. Location, and imaging findings on computed tomography (CT) and conventional MR (cMR) imaging may provide important clues to the most likely diagnosis. Moreover, information obtained from advanced MR imaging techniques increase diagnostic confidence and help distinguish between different histologic tumor types. Here we discuss the most common posterior fossa tumors in children, including typical imaging findings on CT, cMR imaging, and advanced MR imaging studies.

Ex vivo generation of dendritic cells from cryopreserved, post-induction chemotherapy, mobilized leukapheresis from pediatric patients with medulloblastoma

Generation of patient-derived, autologous dendritic cells (DCs) is a critical component of cancer immunotherapy with ex vivo-generated, tumor antigen-loaded DCs. An important factor in the ability to generate DCs is the potential impact of prior therapies on DC phenotype and function. We investigated the ability to generate DCs using cells harvested from pediatric patients with medulloblastoma for potential evaluation of DC-RNA based vaccination approach in this patient population. Cells harvested from medulloblastoma patient leukapheresis following induction chemotherapy and granulocyte colony stimulating factor mobilization were cryopreserved prior to use in DC generation. DCs were generated from the adherent CD14+ monocytes using standard procedures and analyzed for cell recovery, phenotype and function. To summarize, 4 out of 5 patients (80%) had sufficient monocyte recovery to permit DC generation, and we were able to generate DCs from 3 out of these 4 patient samples (75%). Overall, we successfully generated DCs that met phenotypic requisites for DC-based cancer therapy from 3 out of 5 (60%) patient samples and met both phenotypic and functional requisites from 2 out of 5 (40%) patient samples. This study highlights the potential to generate functional DCs for further clinical treatments from refractory patients that have been heavily pretreated with myelosuppressive chemotherapy. Here we demonstrate the utility of evaluating the effect of the currently employed standard-of-care therapies on the ex vivo generation of DCs for DC-based clinical studies in cancer patients.

Survivin as a therapeutic target in Sonic hedgehog-driven medulloblastoma

Medulloblastoma (MB) is a highly malignant brain tumor that occurs primarily in children. Although surgery, radiation and high-dose chemotherapy have led to increased survival, many MB patients still die from their disease, and patients who survive suffer severe long-term side effects as a consequence of treatment. Thus, more effective and less toxic therapies for MB are critically important. Development of such therapies depends in part on identification of genes that are necessary for growth and survival of tumor cells. Survivin is an inhibitor of apoptosis protein that regulates cell cycle progression and resistance to apoptosis, is frequently expressed in human MB and when expressed at high levels predicts poor clinical outcome. Therefore, we hypothesized that Survivin may have a critical role in growth and survival of MB cells and that targeting it may enhance MB therapy. Here we show that Survivin is overexpressed in tumors from patched (Ptch) mutant mice, a model of Sonic hedgehog (SHH)-driven MB. Genetic deletion of survivin in Ptch mutant tumor cells significantly inhibits proliferation and causes cell cycle arrest. Treatment with small-molecule antagonists of Survivin impairs proliferation and survival of both murine and human MB cells. Finally, Survivin antagonists impede growth of MB cells in vivo. These studies highlight the importance of Survivin in SHH-driven MB, and suggest that it may represent a novel therapeutic target in patients with this disease.

Pediatric medulloblastoma - update on molecular classification driving targeted therapies

As advances in the molecular and genetic profiling of pediatric medulloblastoma evolve, associations with prognosis and treatment are found (prognostic and predictive biomarkers) and research is directed at molecular therapies. Medulloblastoma typically affects young patients, where the implications of any treatment on the developing brain must be carefully considered. The aim of this article is to provide a clear comprehensible update on the role molecular profiling and subgroups in pediatric medulloblastoma as it is likely to contribute significantly toward prognostication. Knowledge of this classification is of particular interest because there are new molecular therapies targeting the Shh subgroup of medulloblastomas.

MYCN and survivin cooperatively contribute to malignant transformation of fibroblasts

The oncogenes MYCN and survivin (BIRC5) maintain aggressiveness of diverse cancers including sarcomas. To investigate whether these oncogenes cooperate in initial malignant transformation, we transduced them into Rat-1 fibroblasts. Indeed, survivin enhanced MYCN-driven contact-uninhibited and anchorage-independent growth in vitro. Importantly, upon subcutaneous transplantation into mice, cells overexpressing both instead of either one of the oncogenes generated tumors with shortened latency, marked anaplasia and an increased proliferation-to-apoptosis ratio resulting in accelerated growth. Mechanistically, the increased tumorigenicity was associated with an enhanced Warburg effect and a hypoxia inducible factor 1α linked vascular remodeling. This cooperation between MYCN and survivin may be important in the genesis of several cancers.

Hypoxic tumor microenvironment in advanced retinoblastoma

PURPOSE

Retinoblastoma (RB) is a malignant tumor of infancy and childhood. Unfavorable therapeutic response is still a quest in many tumors, including retinoblastoma. Hypoxic tumor microenvironment is one of the factors that determine the therapeutic response in many tumors. The purpose of this study was to determine the presence of hypoxia and its related proteins; Hypoxia inducible factor-1α (HIF-1α), Carbonic anhydrase IX (CA IX) and survivin in RB and their association with clinicopathological features.

MATERIALS AND METHODS

We evaluated the expression of HIF-1α and survivin by immunohistochemistry in 42 archival retinoblastoma tumors and CA IX; a hypoxia marker in 33 tumors in the same cohort. The expression was correlated with tumor groups based on invasion, differentiation and IIRC.

RESULTS

Expression of HIF-1α, survivin and CA IX was observed in 83% (35/42), 86% (36/42), and 93% (31/33) of tumors respectively. We observed no significance between HIF-1α and CA IX expression in tumors with invasion, differentiation and in IIRC tumor groups. An increased survivin expression was observed in group E tumors than in group D tumors (P = 0.044). A significant association was observed between HIF-1α and survivin in differentiated (r = -0.582; P = < 0.01) and undifferentiated tumors groups (r = 0.513; P = <0.012). A similar significant association was observed between HIF-1α and CA IX in tumors with high immunoreactivity for HIF-1α (r = 0.833; P = <0.01).

CONCLUSION

Based on these observations, we propose that HIF-1α pathway is deregulated in RB. The role of drug resistance and the potential of targeting HIF-1α, CA IX, and survivin in RB should further examined.

C-erbB2/HER2 in human gliomas, medulloblastomas, and meningiomas: a minireview

C-erbB2/HER2 serves as an important prognostic and predictive biomarker in various human tumors, especially in breast cancer, whereas its role in human intracranial tumors is more uncertain. We therefore performed a search in PubMed to get an update. This literature review comprises immunohistochemical studies on the clinical significance of c-erbB2/HER2 overexpression in gliomas, medulloblastomas, and meningiomas. In general, the findings were discrepant with regard to correlations between overexpression, tumor grade, and prognosis. Use of various antibodies may be a contributing factor to these discrepancies. Standardization of the immunohistochemical procedures is a relevant topic for discussion.

Survivin expression in medulloblastoma: a possible marker for survival

Medulloblastomas are highly invasive tumors which are generally disseminated at the time of diagnosis. High and continued morbidity and mortality have prompted the search for new biologic markers that might be used for targeted therapy to minimise treatment related side effects. In this work, we studied the positive expression of survivin in medulloblastoma and investigated its relation to clinical, pathologic data and survival. Tumor tissue specimens from 47 patients with medulloblastoma who underwent primary surgical treatment from June 2002 to June 2006 at the Mansoura university hospital, Egypt were collected. Paraffin sections of all samples were submitted for immunohistochemistry using anti-survivin antibody. The relation between the percentage of positive survivin cells with clinical, pathological and survival data was evaluated.

RESULTS

In 47 cancer tissue specimens, one case large-cell-anaplastic (1.12 %), tweleve cases desmoplastic (25.53 %) and 34 cases classic medulloblastomas (72.34 %). The immunohistochemical expression of survivin was nulear with moderate intensity. It does not correlate with either age or sex. There was a significant negative correlation of survivin expression with survival (p < 0.001), where negative survivin immunostaining was associated with prolonged overall and disease free survival, while survivin expression was associated with shortened survival.

CONCLUSION

Survivin expression correlate with the clinical outcome with poor prognosis and could be a potential predictive factor for recurrence or metastasis.

Predicting relapse in patients with medulloblastoma by integrating evidence from clinical and genomic features

PURPOSE

Despite significant progress in the molecular understanding of medulloblastoma, stratification of risk in patients remains a challenge. Focus has shifted from clinical parameters to molecular markers, such as expression of specific genes and selected genomic abnormalities, to improve accuracy of treatment outcome prediction. Here, we show how integration of high-level clinical and genomic features or risk factors, including disease subtype, can yield more comprehensive, accurate, and biologically interpretable prediction models for relapse versus no-relapse classification. We also introduce a novel Bayesian nomogram indicating the amount of evidence that each feature contributes on a patient-by-patient basis.

PATIENTS AND METHODS

A Bayesian cumulative log-odds model of outcome was developed from a training cohort of 96 children treated for medulloblastoma, starting with the evidence provided by clinical features of metastasis and histology (model A) and incrementally adding the evidence from gene-expression-derived features representing disease subtype-independent (model B) and disease subtype-dependent (model C) pathways, and finally high-level copy-number genomic abnormalities (model D). The models were validated on an independent test cohort (n = 78).

RESULTS

On an independent multi-institutional test data set, models A to D attain an area under receiver operating characteristic (au-ROC) curve of 0.73 (95% CI, 0.60 to 0.84), 0.75 (95% CI, 0.64 to 0.86), 0.80 (95% CI, 0.70 to 0.90), and 0.78 (95% CI, 0.68 to 0.88), respectively, for predicting relapse versus no relapse.

CONCLUSION

The proposed models C and D outperform the current clinical classification schema (au-ROC, 0.68), our previously published eight-gene outcome signature (au-ROC, 0.71), and several new schemas recently proposed in the literature for medulloblastoma risk stratification.

Low-level copy number changes of MYC genes have a prognostic impact in medulloblastoma

High-level amplifications of MYC genes are associated with poor outcomes in childhood medulloblastoma (MB). However, the occurrence of MYCN and MYCC copy number increases below the intense amplification pattern is rarely reported, and its clinical impact has not yet been determined. Here, we describe this phenomenon and its prognostic significance in a cohort of 29 MB patients. Using interphase fluorescence in situ hybridization (I-FISH), low-level copy number alterations, i.e. gain of MYCN, were shown in 5/27 (19%) samples, whereas amplification was revealed in only 1/27 (4%) samples. MYCC gain was revealed in 6/29 (21%) MB, while amplification was disclosed in only 2/29 (7%). Hyperploidy and co-incidence of gains in both MYC loci were frequently observed in samples with copy number aberrations. Survival analysis has clearly shown that MYC copy number increases are associated with lowered event-free survival and overall survival in MB. In the case of MYCN, this negative correlation was statistically significant. We conclude that limited numerical alterations in loci 2p24 (MYCN) and 8q24 (MYCC), as assessed by I-FISH, are present in MB with a higher frequency than high-level amplifications. Poor prognoses were observed in patients with copy number increases in MYC genes. Our data illustrate the importance of further investigations in multicenter trials to better refine the emerging genomic-based prognostic stratification in MB.

Childhood medulloblastoma: current status of biology and treatment

Medulloblastoma, a primitive neuro-ectodermal tumour that arises in the posterior fossa, is the most common malignant brain tumour occurring in childhood. Over the past half century, the long-term survival for children with medulloblastoma has improved remarkably from a certain fatal diagnosis to a cancer that is often curable. Although overall survival for children with non-disseminated and non-anaplastic medulloblastoma can approach 80%, the current multidisciplinary therapeutic approach is not without long-term sequelae. Chemotherapy has improved the long-term survival and allowed for reductions in the amount of radiation given, thereby reducing some of the long-term toxicities. In this review, we describe the current understanding of the basic biology of medulloblastoma and report on the current active chemotherapeutic agents utilized in medulloblastoma therapy. Ultimately, our understanding of the basic biology of medulloblastoma may lead to further advances in therapy by providing targets that are more specific and potentially less toxic.

Curcumin inhibits the Sonic Hedgehog signaling pathway and triggers apoptosis in medulloblastoma cells

Medulloblastoma is an aggressive primary brain tumor that arises in the cerebellum of children and young adults. The Sonic Hedgehog (Shh) signaling pathway that plays important roles in the pathology of this aggressive disease is a promising therapeutic target. In the present report we have shown that curcumin has cytotoxic effects on medulloblastoma cells. Curcumin suppressed also cell proliferation and triggered cell-cycle arrest at G(2)/M phase. Moreover, curcumin inhibited the Shh-Gli1 signaling pathway by downregulating the Shh protein and its most important downstream targets GLI1 and PTCH1. Furthermore, curcumin reduced the levels of beta-catenin, the activate/phosphorylated form of Akt and NF-kappaB, which led to downregulating the three common key effectors, namely C-myc, N-myc, and Cyclin D1. Consequently, apoptosis was triggered by curcumin through the mitochondrial pathway via downregulation of Bcl-2, a downstream anti-apoptotic effector of the Shh signaling. Importantly, the resistant cells that exhibited no decrease in the levels of Shh and Bcl-2, were sensitized to curcumin by the addition of the Shh antagonist, cyclopamine. Furthermore, we have shown that curcumin enhances the killing efficiency of nontoxic doses of cisplatin and gamma-rays. In addition, we present clear evidence that piperine, an enhancer of curcumin bioavailability in humans, potentiates the apoptotic effect of curcumin against medulloblastoma cells. This effect was mediated through strong downregulation of Bcl-2. These results indicate that curcumin, a natural nontoxic compound, represents great promise as Shh-targeted therapy for medulloblastomas.

Universal poor survival in children with medulloblastoma harboring somatic TP53 mutations

PURPOSE

Medulloblastoma is the prototype of treatment success in modern pediatric neuro-oncology. Unfortunately, 20% to 30% of tumors recur despite maximal resection and multimodal therapy. Multiple biologic prognostic markers have been investigated to predict recurrences, but controversy remains regarding their clinical utility. Because p53 immunopositivity is an adverse prognostic marker in pediatric medulloblastoma and TP53 mutations are associated with chemotherapy and radiation therapy resistance, we aimed to determine the extent and role of TP53 mutations in pediatric medulloblastoma treatment failure.

PATIENTS AND METHODS

One hundred eight of 111 consecutive patients diagnosed with medulloblastoma in our institution from 1995 to 2007 were included. Median follow-up time was 5.3 years in survivors. All samples were immunostained for p53 and erbB-2. Histologic grade and immunostaining were scored by two blinded reviewers. For 49 patients, frozen material was available for TP53 sequencing. The main outcome measures were overall and progression-free survival.

RESULTS

Sixteen percent of sequenced medulloblastomas harbored a TP53 mutation. As a screening test, p53 immunohistochemistry was 100% sensitive and 83% specific for a TP53 mutation. Strikingly, all mutated tumors recurred early, and 5-year survival for average-risk patients was 0% for TP53-mutated medulloblastoma compared with 74% +/- 8% for wild-type medulloblastoma (P < .0001). Furthermore, 75% of recurrences in average-risk patients were associated with TP53 mutations. On multivariate analysis, TP53 mutation status was the strongest adverse prognostic factor (hazard ratio = 10.4, P = .003).

CONCLUSION

Lack of long-term survival in TP53-mutated medulloblastomas highlights the role of TP53 mutations in medulloblastoma resistance to conventional therapies and the need for alternative treatments, and prospective validation of these findings is needed.

[Differential aspects in children and adult patients with medulloblastoma]

BACKGROUND AND OBJECTIVE

Medulloblastoma is the more frequent malignant cerebral tumor in childhood.

PATIENTS AND METHODS

This is an observational study of a retrospective cohort in which there were included all the patients diagnosed of medulloblastoma in the last 19 years (1989-2007) in Hospital de Cruces of Baracaldo, Vizcaya, Spain.

RESULTS

There were included 37 patients, 20 men and 17 women, with ages between 1 and 48 years (average age 13.7 years with standard deviation 11.4). Tumor site and mortality according to initial dissemination were variables of statistic significance. Metastases were detected at diagnosis in two patients. The surgical resection was total in 75% of the patients. A relapse was diagnosed in the follow-up in 59.5% of the patients, with a positive spinal fluid in 27%. Sequelae were detected in 100% of the survivors, mainly with cerebellar and ocular alterations. One patient developed a meningioma and a maxillary sarcoma at the long term follow-up. It is important to emphasize the aggressiveness of medulloblastoma in both children and adults, with a global mortality of 56.8% and 48,6% at 5 years.

CONCLUSIONS

It is considered necessary a multidisciplinary treatment and a long term monitoring of the patients and the sequelae of the survivors, including the possibility of second tumours.

Beta-catenin status in paediatric medulloblastomas: correlation of immunohistochemical expression with mutational status, genetic profiles, and clinical characteristics

Medulloblastoma is the most frequent malignant paediatric brain tumour. The activation of the Wnt/beta-catenin pathway occurs in 10-15% of medulloblastomas and has been recently described as a marker for favourable patient outcome. We report a series of 72 paediatric medulloblastomas evaluated for beta-catenin protein expression, CTNNB1 mutations, and comparative genomic hybridization. Gene expression profiles were also available in a subset of 40 cases. Immunostaining of beta-catenin showed extensive nuclear staining (>50% of the tumour cells) in six cases and focal nuclear staining (<10% of cells) in three cases. The other cases either exhibited a signal strictly limited to the cytoplasm (58 cases) or were negative (five cases). CTNNB1 mutations were detected in all beta-catenin extensively nucleopositive cases. The expression profiles of these cases documented strong activation of the Wnt/beta-catenin pathway. Remarkably, five out of these six tumours showed a complete loss of chromosome 6. In contrast, cases with focal nuclear beta-catenin staining, as well as tumours with negative or cytoplasmic staining, never demonstrated CTNNB1 mutation, Wnt/beta-catenin pathway activation or chromosome 6 loss. Patients with extensive nuclear staining were significantly older at diagnosis and were in continuous complete remission after a mean follow-up of 75.7 months (range 27.5-121.2 months) from diagnosis. All three patients with focal nuclear staining of beta-catenin died within 36 months from diagnosis. Altogether, these data confirm and extend previous observations that CTNNB1-mutated tumours represent a distinct molecular subgroup of medulloblastomas with favourable outcome, indicating that therapy de-escalation should be considered. International consensus on the definition criteria of this distinct medulloblastoma subgroup should be achieved.

Embryonal neural tumours and cell death

Medulloblastoma and neuroblastoma are malignant embryonal childhood tumours of the central and peripheral nervous systems, respectively, which often show poor clinical prognosis due to resistance to current chemotherapy. Both these tumours have deficient apoptotic machineries adopted from their respective progenitor cells. This review focuses on the specific background for tumour development, and highlights biological pathways that present potential targets for novel therapeutic approaches.

Role of Hypoxia-inducible factor-1 alpha and Survivin in colorectal carcinoma progression

BACKGROUND AND AIMS

Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is the main active subunit of HIF-1 that promoted tumor cells survival and critical steps in tumor progression and aggressiveness. The authors aimed to investigate the role of HIF-1 alpha and Survivin in colorectal cancer (CRC) progression.

MATERIALS AND METHODS

Plasmid expressing small interfering RNA (siRNA) against HIF-1 alpha was constructed and transfected into LS174T cells with Lipofectamine. The LS174T cells were incubated for 24 h under hypoxic condition. The inhibitory effects of siRNA on HIF-1 alpha gene was determined by semiquantitative reverse transcriptase polymerase chain reaction and Western blot. Expression of HIF-1 alpha and Survivin was investigated by immunohistochemistry in colorectal adenocarcinomas tissue microarrays.

RESULTS

HIF-1 alpha and Survivin expressions were markedly downregulated after the siRNA expression vector against HIF-1 alpha was transfected into the LS174T cells. Of the eight adenoma lesions, one case (12.25%) and four cases (50%) were positive for HIF-1 alpha and Survivin, respectively. Of the 69 cases of CRCs, 46 cases (66.7%) and 39 cases (56.5%) were positive for HIF-1 alpha and Survivin, respectively. The positive rate of HIF-1 alpha protein in CRCs was significantly higher than that in colorectal adenoma lesions (P < 0.05). HIF-1 alpha protein expression was significantly higher in patients with stage III than in patients with stage I-II CRCs (P < 0.01). In addition, overexpression of HIF-1 alpha in higher stages of CRCs was found to correlate positively with Survivin levels (P < 0.001).

CONCLUSIONS

Our data demonstrate that HIF-1 alpha and Survivin are mostly expressed in invasive CRCs. Inhibition of HIF-1 alpha may lead to exploration of its potential as a diagnostic tool and possibly a target for gene therapy for colorectal carcinoma.

Biological background of pediatric medulloblastoma and ependymoma: a review from a translational research perspective

Survival rates of pediatric brain tumor patients have significantly improved over the years due to developments in diagnostic techniques, neurosurgery, chemotherapy, radiotherapy, and supportive care. However, brain tumors are still an important cause of cancer-related deaths in children. Prognosis is still highly dependent on clinical characteristics, such as the age of the patient, tumor type, stage, and localization, but increased knowledge about the genetic and biological features of these tumors is being obtained and might be useful to further improve outcome for these patients. It has become clear that the deregulation of signaling pathways essential in brain development, for example, sonic hedgehog (SHH), Wnt, and Notch pathways, plays an important role in pathogenesis and biological behavior, especially for medulloblastomas. More recently, data have become available about the cells of origin of brain tumors and the possible existence of brain tumor stem cells. Newly developed array-based techniques for studying gene expression, protein expression, copy number aberrations, and epigenetic events have led to the identification of other potentially important biological abnormalities in pediatric medulloblastomas and ependymomas.

Medulloblastoma in childhood: new biological advances

Medulloblastoma is the most common embryonal tumour in children. Patients with medulloblastoma are currently staged as average-risk or poor-risk on the basis of clinical findings. With current multimodality therapy, nearly 90% of children with average-risk, non-disseminated medulloblastoma have 5-year event-free survival, and those with high-risk disease have a 60-65% survival rate; however, the outcome for younger children, particularly infants, is worse. Children who survive medulloblastoma are at risk of long-term sequelae related to the neurological effects of the tumour, surgery, or radiotherapy, and the additive effects of chemotherapy. Molecular biology has changed our understanding of medulloblastoma and has implications for diagnostic stratification and treatment. As newer biological agents are translated from the lab to the bedside, clinicians need to understand the fundamental signalling pathways that are targeted during therapy. Greater understanding of the molecular biology of medulloblastoma is needed so that more children can be cured or have an improved quality of life.