Prognosis-Related Molecular Markers in Pediatric Central Nervous System Tumors

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

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.

Characterization of EGFR family gene aberrations in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly lethal malignancy of the biliary tract with very few treatment options. Epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor (HER2) have been considered as potential therapeutic targets in CCA. In the present study, we attempted to clarify the clinicopathological significance of all EGFR family members, EGFR, HER2, HER3 and HER4, across the full spectrum of CCAs. Immunohistochemistry and FISH were performed to validate expressions and genetic aberrations of these molecules retrospectively in 175 CCA patients. EGFR, HER3 and HER4 were overexpressed in 20 (30.8%), 8 (12.3%) and 41 (63.1%) of the 65 intrahepatic cholangiocarcinomas (IHCCs), and in 23 (20.9%), 13 (11.8%) and 62 (56.4%) of the 110 extrahepatic cholangiocarcinomas (EHCCs), respectively. Overexpression of HER2 was exclusively identified in EHCCs, among which the rate was 4.5% (5/110). A significant association was identified between EGFR amplification and EGFR overexpression (P=0.002). Similarly, HER2 amplification was strongly associated with HER2 overexpression (P<0.001). Multivariate analysis suggested that EGFR overexpression is an independent prognostic factor in IHCC, but not in EHCC cases [HR (95% CI): 3.689 (1.253-10.587), P=0.018]. Notably, for the first time, we demonstrated HER4 expression is a prognostic factor in EGFR-negative IHCC patients. In vitro data further suggested a tumor-suppressor role of HER4 in CCA. siRNA knockdown of HER4 significantly increased RBE cell migration and invasion. By contrast, HER4 overexpression decreased proliferation of HuCCT-1 cells and their migratory and invasive capacity. In summary, our results revealed expression of the EGFR family members in CCA development and progression. CCAs differentially express HER2 protein based on tumor location. HER4 expression status allows stratification of CCA patients into different survival categories.

Use of brightness wavelet transformation for automated analysis of serum metallothioneins- and zinc-containing proteins by Western blots to subclassify childhood solid tumours

In this study, we determined serum levels of metallothioneins (MTs) and zinc in children with solid tumours (neuroblastoma, Hodgkin lymphoma, medulloblastoma, osteosarcoma, Ewing sarcoma and nephroblastoma) by differential pulse voltammetry Brdicka reaction and ELISA. Zn(II) level in patients sera was 40% compared to controls, contrariwise, MT level was 4.2 × higher in patients. No significant differences among single diagnoses were found both for Zn(II) and MT. When determined Zn(II)/MT ratio, in controls its value was 24.6, but it was 2.6 in patients. After Western-blotting with anti-MT and anti-Zn chicken antibodies, variable intensities of the bands within the samples were observed. The brightness curve obtained for each sample both for MT- and Zn blots was further analysed to produce a list of band positions together with some complementary information related to the intensity of the observed bands by the optimised algorithm. We constructed from those profiles decision trees that enable to distinguish different groups of tumours. The blood samples were heat-treated, in which we supposed mainly MT, but samples contained other thermostable Zn-containing proteins that were helpful for identification of embryonal tumours with 88% accuracy and for identification of sarcomas with 78% accuracy. In MT blots the accuracies were 53 and 45%, respectively. Simultaneous analysis of MT and Zn blots did not increased accuracy of identification neither in embryonal tumours (80%) nor in sarcomas. Those results are promising not only from diagnostic point of view but particularly in the area of studying of individual MT isoforms and their aggregates in malignant tumours.

Metallothioneins and zinc in cancer diagnosis and therapy

Metallothioneins (MTs) are involved in protection against oxidative stress (OS) and toxic metals and they participate in zinc metabolism and its homeostasis. Disturbing of zinc homeostasis can lead to formation of reactive oxygen species, which can result in OS causing alterations in immunity, aging, and civilization diseases, but also in cancer development. It is not surprising that altered zinc metabolism and expression of MTs are of great interest in the case of studying of oncogenesis and cancer prognosis. The role of MTs and zinc in cancer development is tightly connected, and the structure and function of MTs are strongly dependent on Zn²⁺ redox state and its binding to proteins. Antiapoptic effects of MTs and their interactions with proteins nuclear factor kappa B, protein kinase C, esophageal cancer-related gene, and p53 as well as the role of MTs in their proliferation, immunomodulation, enzyme activation, and interaction with nitric oxide are reviewed. Utilization of MTs in cancer diagnosis and therapy is summarized and their importance for chemoresistance is also mentioned.

TrkC plays an essential role in breast tumor growth and metastasis

Tropomyosin-related kinase (Trk) C, a member of the Trk family of neurotrophin receptors, has been implicated in the growth and survival of human cancer tissues. Here, we report that TrkC is frequently overexpressed in human breast cancers and plays an essential role in tumor growth and metastasis. Ectopic expression of TrkC in non-malignant mammary epithelial cells suppressed anoikis, which correlated with activation of the Ras-mitogen-activated protein kinase and phosphatidylinositol-3-OH kinase (PI3K)/Akt pathways, and reduced expression of the metastatic regulator Twist. Furthermore, suppression of TrkC expression in highly metastatic mammary carcinoma cells inhibited their growth in vitro, as well as their ability to metastasize from the mammary gland to the lung in vivo. These results have identified TrkC as a critical regulator of breast cancer cell growth and metastasis.

Biological therapy for pediatric malignancy: current perspectives

Biologicals are defined as agents that are either uniquely or partially tumor-specific. Great expectations were raised by the success in agents that target a specific genetic translocation: all-trans retinoic acid, targeting the chronic myeloid leukemia retinoic acid receptor in acute promyelocytic leukemia and imatinib, a small molecule targeting the BCR-ABL translocation in chronic myeloid leukemia (CML). Thus far, the search for similar "druggable" genetic targets in pediatric cancers has not yet resulted in such dramatic results. The rarity of pediatric cancer as well as ethical considerations necessitate that the agents for testing be carefully and rigorously selected. Biologicals present an additional challenge, as they often do not lend themselves to in vitro testing. Early approaches to specific targeting of solid tumors utilized monoclonal antibodies. The microenvironment provides an interesting new biological approach to treating tumors and alteration of the host immune response provides another avenue. Biological agents are a step forward in supportive care to reduce the hematological toxicity of high-dose chemotherapy and to manage the frequent infectious complications.

c-Src is required for tropomyosin receptor kinase C (TrkC)-induced activation of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway

TrkC mediates many aspects of growth and development in the central nervous system. TrkC is expressed in a variety of non-neuronal tissues as well as human cancers. TrkC overexpression may drive tumorigenesis, invasion, and metastatic capability in cancer cells. However, relatively little is known about whether TrkC activity is also essential to maintain the malignant properties in human tumors. TrkC expression leads to the constitutive activation of two major effector pathways, namely the Ras-MAP kinase (MAPK) mitogenic pathway and the phosphatidylinositol 3-kinase (PI3K)-AKT pathway mediating cell survival. However, it remains unclear how TrkC activates Ras-Erk1/2 and/or PI3K-Akt cascades. Here we define some aspects of the molecular mechanisms regulating TrkC-dependent Ras-Erk1/2 and PI3K/Akt activation. We show that endogenous TrkC associated with c-Src in human and mouse cancer cells which express TrkC. TrkC-c-Src complexes were also detected in primary human breast cancer tissues. Suppression of c-Src by RNA interference in highly metastatic 4T1 mammary cancer cells, which express endogenous TrkC, resulted in markedly decreased expression of cyclin D1 and suppression of activation of Ras-Erk1/2 and PI3K-Akt. Moreover, inhibition of c-Src expression almost completely blocks colony formation of 4T1 cells in soft agar. Furthermore, in c-Src-deficient SYF cells, TrkC failed to activate the PI3K-Atk pathway, but not the Ras-Erk1/2 pathway. Therefore these data indicate that TrkC induces the PI3K-Akt cascade through the activation of c-Src.

TrkC binds to the type II TGF-beta receptor to suppress TGF-beta signaling

Growing evidence suggests that overexpression of TrkC, a member of the Trk family of neurotrophin receptors, could drive tumorigenesis, invasion and metastatic capability in cancer cells. However, relatively little is known about the mechanism of TrkC-mediated oncogenesis. The TrkC gene is a partner of the Tel-TrkC (ETV6-NTRK3) chimeric tyrosine kinase, a potent oncoprotein expressed in tumors derived from multiple cell lineages. Recently, we have shown that ETV6-NTRK3 suppresses transforming growth factor-beta (TGF-beta) signaling by directly binding to the type II TGF-beta receptor (TbetaRII). Here, we report that expression of TrkC also suppresses TGF-beta-induced Smad2/3 phosphorylation and transcriptional activation. Silencing TrkC expression by small interfering RNA in the highly metastatic 4T1 mammary tumor cell line expressing endogenous TrkC significantly enhanced TGF-beta-induced Smad2/3 phosphorylation and restored TGF-beta growth inhibitory activity. In contrast, expression of TrkC in 67NR cells, in which TrkC is not expressed, suppressed TGF-beta transcriptional activation. Moreover, we show that TrkC directly binds to the TbetaRII, thereby preventing it from interacting with the type I TGF-beta receptor (TbetaRI). These results indicate that TrkC is an inhibitor of TGF-beta tumor suppressor activity.

De novo proximal duplication of 1(q12q22) in a female infant with multiple congenital anomalies

Reports of small proximal 1q duplications are rare. We report a 1 month-old female who was referred to clinic because she was believed to have features suggestive of Turner syndrome. The patient's dysmorphic features included a prominent nose, low-set and crumpled ears, slightly high palate, short neck, high-pitched cry, mild micrognathia, hypoplastic labia majora, and somewhat deep palmar creases. Traditional G-band chromosome studies of the patient were interpreted as 46,XX,dup(1)(q12q21). To further evaluate the extent of the chromosome 1 duplication, Spectral Karyotyping and a series of six fluorescence in situ hybridization (FISH) probes were utilized. The FISH probes refined the extent of the duplication to involve the region 1(q12q22) indicating the duplicated segment was larger than interpreted by the G-banding studies. This first case of non-mosaic proximal duplication of 1q to be characterized by multiple locus specific FISH probes should allow a more refined delineation of the phenotypic findings and clinical significance associated with this rare chromosomal duplication.

Ependymoma gene expression profiles associated with histological subtype, proliferation, and patient survival

Ependymomas are primary tumors of the central nervous system that typically originate from the walls of the cerebral ventricles or from the spinal canal. The pathogenesis of these tumors is poorly understood, and prognostic assessment based on histologic features and clinical parameters is difficult. The aim of this study was to investigate the molecular heterogeneity of ependymomas. We used cDNA microarrays and RT-PCR to examine gene expression in 47 ependymomas. We present results for five comparisons: (1) tumors from children and adults with poor versus favorable outcome, (2) tumors from children with poor versus favorable outcome, (3) tumors with high versus low proliferation indices, (4) subependymomas versus myxopapillary ependymomas, and (5) spinal versus intracranial ependymomas. For patients with an overall survival >10 years after diagnosis, we identified 27 genes associated with favorable prognosis. In contrast, overexpression of BNIP3, MRC1, EPHB3, GLIS3, CDK4, COL4A2, EBP, NRCAM, and CCNA1 genes in tumors with high proliferation indices was associated with a poor outcome. Thirty genes, including ETV6, YWHAE, TOP2A, TLR2, IRAK1, TIA1, and UFD1L were found to be highly expressed in subependymomas but not myxopapillary ependymomas. Also, 30 genes were differentially expressed in spinal versus intracranial ependymomas. There was no relationship between expression profiles and tumor grade, patient age, and patient gender. Our results provide insight into specific molecular events underlying ependymoma tumorigenesis and may contribute to more accurate diagnosis and prediction of clinical outcome.

Molecular genetics of pediatric central nervous system tumors

Recent advances in molecular biology have enhanced our understanding of the pathogenesis of brain tumors, particularly in children. The use of molecular diagnostic tools is quickly becoming a standard component in the diagnosis and classification of brain tumors in children, in addition to providing insight leading to treatment stratification and improved outcome prediction. All new protocols involving treatments for brain tumors in children include studies of biomarkers and biologic correlates as a means to identify new targets for therapeutics and possible intervention strategies.

c-Myc downregulation: a critical molecular event in resveratrol-induced cell cycle arrest and apoptosis of human medulloblastoma cells

The correlation of c-Myc expression with resveratrol-induced turnover of medulloblastoma cells was investigated in this study by checking (1) c-Myc expression in medulloblastoma tissues and cell lines (UW228-2 and UW228-3), (2) the in vitro effect of resveratrol on c-Myc expression and (3) the influences of c-Myc inhibition in cell growth and survival. Immunohistochemical staining of human medulloblastomas and noncancerous cerebellar tissues revealed that 8 out of 11 tumor tissues (72.7%) expressed c-Myc, in which 4 cases (50%) showed intensified nuclear labeling. RT-PCR, Western blotting, immunocytochemical and immunofluorescence stainings revealed c-Myc downregulation accompanied with growth suppression and apoptosis. Flow cytometry analysis showed S phase arrest in resveratrol-treated cell populations. Transfection of c-Myc directed antisense oligonucleotides to the cultured medulloblastoma cells could reduce c-Myc expression, inhibit cell growth and arrest the cell cycle at S phase. Our results thus for the first time demonstrate that c-Myc downregulation is a critical molecular event of resveratrol-mediated anti-medulloblastoma activity, which is closely associated with growth suppression, cell cycle arrest and apoptosis of medulloblastoma cells.

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.