Prediction of prognosis in children with medulloblastoma by using immunohistochemical analysis and tissue microarray

Prognostic value of Ki-67 index in adult medulloblastoma after accounting for molecular subgroup: a retrospective clinical and molecular analysis

INTRODUCTION

Medulloblastoma (MB) is a rare primary brain tumor in adults. We previously evaluated that combining both clinical and molecular classification could improve current risk stratification for adult MB. In this study, we aimed to identify the prognostic value of Ki-67 index in adult MB.

METHOD

Ki-67 index of 51 primary adult MBs was reassessed using a computer-based image analysis (Image-Pro Plus). All patients were followed up ranging from 12 months up to 15 years. Gene expression profiling and immunochemistry were used to establish the molecular subgroups in adult MB. Combined risk stratification models were designed based on clinical characteristics, molecular classification and Ki-67 index, and identified by multivariable Cox proportional hazards analysis.

RESULTS

In our cohort, the mean Ki-67 value was 30.0 ± 11.3% (range 6.56-63.55%). The average Ki-67 value was significantly higher in LC/AMB than in CMB and DNMB (P = .001). Among three molecular subgroups, Group 4-tumors had the highest average Ki-67 value compared with WNT- and SHH-tumors (P = .004). Patients with Ki-67 index large than 30% displayed poorer overall survival (OS) and progression free survival (PFS) than those with Ki-67 less than 30% (OS: P = .001; PFS: P = .006). Ki-67 index (i.e. > 30%, < 30%) was identified as an independent significant prognostic factor (OS: P = .017; PFS: P = .024) by using multivariate Cox proportional hazards model.

CONCLUSIONS

In conclusion, Ki-67 index can be considered as a valuable independent prognostic biomarker for adult patients with MB.

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.

Neuronal differentiation associated with Gli3 expression predicts favorable outcome for patients with medulloblastoma

Medulloblastoma (MB) is a malignant cerebellar tumor arising in children, and its ontogenesis is regulated by Sonic Hedgehog (Shh) signaling. No data are available regarding the correlation between expression of Gli3, a protein lying downstream of Shh, and neuronal differentiation of MB cells, or the prognostic significance of these features. We re-evaluated the histopathological features of surgical specimens of MB taken from 32 patients, and defined 15 of them as MB with neuronal differentiation (ND), three as MB with both glial and neuronal differentiation (GD), and 14 as differentiation-free (DF) MB. Gli3-immunoreactivity (IR) was evident as a clear circular stain outlining the nuclei of the tumor cells. The difference in the frequency of IR between the ND+GD (94.4%) and DF (0%) groups was significant (P < 0.001). The tumor cells with ND showed IR for both Gli3 and neuronal nuclei. Ultrastructurally, Gli3-IR was observed at the nuclear membrane. The overall survival and event-free survival rates of the patients in the ND group were significantly higher than those in the other groups. The expression profile of Gli3 is of considerable significance, and the association of ND with this feature may be prognostically favorable in patients with MB.

Differential proliferative index of cancer stem-like cells in primary and recurrent medulloblastoma in human

PURPOSE

Medulloblastoma is the most common malignant primitive neuroectodermal tumor found in children. It has a tendency to recur at a primary or distant site. The mechanism underlying the regulation of the recurrence of medulloblastoma remains largely unknown. Recently, several reports have described that cancer stem-like cells (CSCs) can be identified and isolated in medulloblastoma. The authors therefore attempted to demonstrate the correlation between the biological features of medulloblastoma's CSCs and its recurrence.

METHODS

The data used were obtained in five consecutive patients with medulloblastomas who subsequently experienced tumor recurrence from 2004 to 2007. The authors performed the immunohistochemical assays to analyze the expression of CSC markers, proliferation features, and proliferative status of CSCs in primary and recurrent medulloblastoma.

RESULTS

Of the five patients, two had recurrence at the primary site and three had a distant recurrence. CSC markers such as CD133(Prominin-1), DCX, PSA-NCAM, TUC-4, and nestin were expressed regardless of primary or recurrent medulloblastoma. All the five tumor specimens had a high proliferation index (PI). The PI was even higher in the group of patients after recurrence at a distant site (p<0.05), while the PI remained almost the same after primary recurrence. The Ki67/nestin-, Ki67/DCX-, and Ki67/TUC-4-positive cells were significantly increased in recurrent medulloblastoma at both the primary and distant sites, whereas CSCs in primary medulloblastoma showed much lower proliferative features (p<0.05).

CONCLUSIONS

Our data suggest that tumorigenesis of medulloblastomas and their recurrence might be related to CSCs. More proliferating CSCs in medulloblastomas denote worse prognosis.

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.

High expression of stathmin protein predicts a fulminant course in medulloblastoma

OBJECT

Stathmin, an important cytosolic phosphoprotein, is involved in cell proliferation and motility. This study was performed to elucidate the role of stathmin in the progression of medulloblastoma.

METHODS

The expression of stathmin protein was examined by immunohistochemical staining of tumor sections obtained in 17 consecutive patients with medulloblastoma who underwent resection between 1995 and 2005. Four patients were excluded because they were either lost to follow-up or underwent biopsy sampling only, leaving a total of 13 patients in the study. The stathmin expression was scored according to the immunoreactive fraction of tumor cells, and the level was correlated with various clinicopathological factors.

RESULTS

The expression level of stathmin protein was < or = 10% in 9 patients, 11-50% in 1, and > 50% in 3. No staining was seen in the tissues adjacent to the tumors. For comparison, the authors grouped the expression level of stathmin into high (> 50%) and low (< or = 50%). It was found that patients with high expression of stathmin had more frequent tumor dissemination at the time of resection or soon after total excision of the tumor (p = 0.0035), and hence experienced a fulminant course with lower patient survival (p < 0.0001), with an average survival period of 6.7 months (range 2-10 months). The expression level of stathmin did not correlate with patient age, sex, CSF cytological findings, use of adjuvant therapies, Ki 67 index, or risk classification of the tumors according to previously described categories in the literature.

CONCLUSIONS

High stathmin expression correlates with tumor dissemination, is an important prognostic factor of medulloblastoma, and may serve as a useful marker for more intensive adjuvant therapies.