Association of MYCN Amplification and 1p Deletion in Neuroblastomas with High Tumor Vascularity

Dynamic Changes in Microvascular Density Can Predict Viable and Non-Viable Areas in High-Risk Neuroblastoma

Despite aggressive treatments, the prognosis of high-risk NB remains poor. Surgical oncology needs innovative intraoperative devices to help surgeons discriminate malignant tissue from necrotic and surrounding healthy tissues. Changes within the tumor vasculature could be used intraoperatively as a diagnostic tool to guide surgical resection. Here, we retrospectively analyzed the mean vascular density (MVD) of different NB subtypes at diagnosis and after induction chemotherapy using scanned histological samples. One patient was prospectively enrolled, and an ex vivo photoacoustic imaging (PAI) scan was performed on two representative sections to assess its capacity to discriminate different tumor regions. We found that post-chemotherapy, viable areas of differentiating NBs and ganglioneuroblastomas are associated with higher MVD compared to poorly differentiated NBs. Early necrotic regions showed higher MVD than late necrotic and viable regions. Finally, calcified areas showed significantly lower MVD than any other histological component. The acquired PAI images showed a good high-resolution ex vivo 3D delineation of NB margins. Overall, these results suggest that a high-definition preclinical imaging device such as PAI could potentially be exploited to guide surgical resection by identifying different vasculature signatures.

Lymph microvascularization as a prognostic indicator in neuroblastoma

Neuroblastoma is the most common extra-cranial solid pediatric cancer and causes approximately 15% of all childhood deaths from cancer. Although lymphatic vasculature is a prerequisite for the maintenance of tissue fluid balance and immunity in the body, little is known about the relationship between lymphatic vascularization and prognosis in neuroblastoma. We used our previously-published custom-designed tool to close open-outline vessels and measure the density, size and shape of all lymphatic vessels and microvascular segments in 332 primary neuroblastoma contained in tissue microarrays. The results were correlated with clinical and biological features of known prognostic value and with risk of progression to establish histological lymphatic vascular patterns associated with unfavorable histology. A high proportion of irregular intermediate lymphatic capillaries and irregular small collector vessels were present in tumors from patients with metastatic stage, undifferentiating neuroblasts and/or classified in the high risk. In addition, a higher lymphatic microvascularization density was found to be predictive of overall survival. Our findings show the crucial role of lymphatic vascularization in metastatic development and maintenance of tumor tissue homeostasis. These patterns may therefore help to indicate more accurate pre-treatment risk stratification and could provide candidate targets for novel therapies.

Vascular patterns provide therapeutic targets in aggressive neuroblastic tumors

Angiogenesis is essential for tumor growth and metastasis, nevertheless, in NB, results between different studies on angiogenesis have yielded contradictory results. An image analysis tool was developed to characterize the density, size and shape of total blood vessels and vascular segments in 458 primary neuroblastic tumors contained in tissue microarrays. The results were correlated with clinical and biological features of known prognostic value and with risk of progression to establish histological vascular patterns associated with different degrees of malignancy. Total blood vessels were larger, more abundant and more irregularly-shaped in tumors of patients with associated poor prognostic factors than in the favorable cohort. Tumor capillaries were less abundant and sinusoids more abundant in the patient cohort with unfavorable prognostic factors. Additionally, size of post-capillaries & metarterioles as well as higher sinusoid density can be included as predictive factors for survival. These patterns may therefore help to provide more accurate pre-treatment risk stratification, and could provide candidate targets for novel therapies.

Chalkley method in the angiogenesis research and its automation via computer simulation

The aim of this study was to develop a computer simulation evaluating microvessel density according to the Chalkley method on digital images taken from neovascular hot spots. An image analysis algorithm has been developed using ImageJ, an extensible, open source image processing and analysis software. The idea was to create a virtual Chalkley point array graticule, and to calculate Chalkley counts automatically by stepwise angular rotation of it on the superimposed images containing properly segmented microvessels. This eliminates the necessity of having the Chalkley graticule, an accessory that has to be mounted on the microscope's ocular. The proposed method is a faithful simulation of the original Chalkley counting procedure. It gives pathologists who do not have the Chalkley graticule an opportunity to evaluate microvessels quantitatively according to the basic principles underlying Chalkley counting. Evaluating microvessel densities in solid tumors is a frequent procedure in angiogenesis research. A few standard methods, including Chalkley counting, are used for the estimation of microvessel density. Several independent studies have shown that the Chalkley counting is more consistent and may provide useful data on prognosis. The obvious disadvantages lie in the facts that this method is time-consuming and requires a special hardware. Computer simulation may overcome these obstacles.

Neuroblastoma and MYCN

Neuroblastoma, the most common extracranial solid tumor of childhood, is thought to originate from undifferentiated neural crest cells. Amplification of the MYC family member, MYCN, is found in ∼25% of cases and correlates with high-risk disease and poor prognosis. Currently, amplification of MYCN remains the best-characterized genetic marker of risk in neuroblastoma. This article reviews roles for MYCN in neuroblastoma and highlights recent identification of other driver mutations. Strategies to target MYCN at the level of protein stability and transcription are also reviewed.

Angiogenin up-regulation correlates with adverse clinicopathological and biological factors, increased microvascular density and poor patient outcome in neuroblastomas

AIMS

As new biomarkers are urgently needed to identify children with high-risk neuroblastoma (NB), we studied the contribution of angiogenin (ANG) to angiogenesis and its association with clinicopathological and biological features and patient outcome in NB.

METHODS AND RESULTS

Ninety NBs and 12 ganglioneuromas (GNs) were immunostained for ANG and CD31. ANG expression in NB tumoral cells (ANG scores) and vessels [ANG microvascular density (MVD)] and total MVD (CD31 MVD) were determined. The ANG score was significantly greater in NBs than in GNs (P = 0.015) and in NBs from children with stage 4 tumours, high-risk disease, unfavourable pathology (P < 0.001 for each), MYCN amplification (P = 0.003), and 1p deletion (P = 0.002). ANG scores correlated with ANG MVD and CD31 MVD (P < 0.001 for each). Total ANG and CD31 protein levels, measured with a sensitive enzyme-linked immunosorbent assay, were highly correlated (P = 0.003). High ANG scores were associated with decreased overall and event-free survival (log-rank test, P = 0.025 and P = 0.018, respectively). High ANG MVD was associated with decreased overall and event-free survival (log-rank test, P = 0.009 and P = 0.026, respectively). High CD31 MVD was associated with decreased event-free survival (P = 0.045).

CONCLUSIONS

The strong correlation of ANG up-regulation with total MVD and adverse clinicopathological and biological factors indicates that ANG supports growth and progression in NB.

Pharmacotherapy of neuroblastoma

IMPORTANCE OF THE FIELD

Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extracranial solid tumor of early life. High risk disease in older children remains a therapeutic challenge, despite high-intensity therapy with correspondingly significant short- and long-term toxicities.

AREAS COVERED IN THIS REVIEW

We have reviewed therapy for neuroblastoma over the last three decades. This includes cytotoxic chemotherapy, immunotherapy, radionuclides, antiangiogenic compounds, and molecularly targeted agents. We provide a perspective on the incorporation of these drugs into therapy for neuroblastoma.

WHAT THE READER WILL GAIN

The reader will gain a better understanding of these novel agents and their targets in neuroblastoma. The reader will also gain insight into the need to define through sequential, carefully designed clinical trials, the roles and toxicities of these therapies, especially if the combination of targeted and conventional cytotoxic agents is used.

TAKE HOME MESSAGE

Advanced-stage neuroblastoma in older infants and children remains a disease that is difficult to cure. New, targeted agents may improve both the therapeutic index and the outcome, but are, for the most part, in early development and present a challenge for clinical trial design given both the rarity of this disease and its responsiveness (albeit incomplete) to currently used cytotoxic agents.

Effect of cytotoxic agents and retinoic acid on Myc-N protein expression in neuroblastoma

AIM

Neuroblastoma is an important pediatric tumor in which Myc-N amplification is a well-known poor prognostic indicator. It has a great diversity in clinical behavior. The effect of pharmacologic agents used in neuroblastoma treatment on Myc-N expression is still unclear.

METHOD

We analyzed Myc-N expression changes by immunocytochemistry in Myc-N-positive Kelly human neuroblastoma cell line using retinoic acid and cytotoxic drugs (cisplatin, vincristine, cyclophosphamide, etoposide, and doxorubicin) and their combinations compared with control conditions. First, concentration of drugs were determined as LD50 doses. Kelly cells and drugs were incubated for 24 hours in 5% CO2, 37 degrees C in 96-well plates. Myc-N expression was scored semiquantitatively as negative, mild, moderate, or high positive.

RESULTS

Myc-N amplification did not change with any agent or combination. It was higher than 20 copies in all conditions. Myc-N protein expression was high in control and doxorubicin group. It was moderate in retinoic acid, cyclophosphamide, retinoic acid combined with cyclophosphamide and retinoic acid combined with doxorubicin groups. The expression was mild in cisplatin, vincristine, etoposide, retinoic acid combined with etoposide, and retinoic acid combined with cisplatin groups. Myc-N expression was negative in retinoic acid combined with vincristine group.

CONCLUSIONS

Myc-N expression is reduced with cytotoxic agents and retinoic acid in neuroblastoma although Myc-N amplification remains the same. Retinoic acid combined with vincristine is the most effective combination to reduce Myc-N expression. Our results suggest that therapeutic applications of these agents as low dose maintenance therapy might be useful.

Genetic markers of mediastinal tumors

Determination of the genetic markers by the application of new genomic methodologies has provided important insight into the pathogenesis of mediastinal disease. These new techniques have enabled scientists to uncover differential gene expression patterns between subtypes of thymomas, correlate tumor marker expression with germ cell tumors, and determine a link between the NF-kappaB and JAK/STAT pathways with Hodgkin's and non-Hodgkin's lymphoma. Despite the progress made in the understanding of genetic markers of select mediastinal tumors, significantly more investigation is required to elucidate the molecular pathways involved in the pathogenesis of these tumors.