Th-MYCN mice with caspase-8 deficiency develop advanced neuroblastoma with bone marrow metastasis.

Neuroblastoma, the most common extracranial pediatric solid tumor, is responsible for 15% of all childhood cancer deaths. Patients frequently present at diagnosis with metastatic disease, particularly to the bone marrow. Advances in therapy and understanding of the metastatic process have been limited due, in part, to the lack of animal models harboring bone marrow disease. The widely used transgenic model, the Th-MYCN mouse, exhibits limited metastasis to this site. Here, we establish the first genetic immunocompetent mouse model for metastatic neuroblastoma with enhanced secondary tumors in the bone marrow. This model recapitulates 2 frequent alterations in metastatic neuroblastoma, overexpression of MYCN and loss of caspase-8 expression. Mouse caspase-8 gene was deleted in neural crest lineage cells by crossing a Th-Cre transgenic mouse with a caspase-8 conditional knockout mouse. This mouse was then crossed with the neuroblastoma prone Th-MYCN mouse. Although overexpression of MYCN by itself rarely caused bone marrow metastasis, combining MYCN overexpression and caspase-8 deletion significantly enhanced bone marrow metastasis (37% incidence). Microarray expression studies of the primary tumors mRNAs and microRNAs revealed extracellular matrix structural changes, increased expression of genes involved in epithelial to mesenchymal transition, inflammation, and downregulation of miR-7a and miR-29b. These molecular changes have been shown to be associated with tumor progression and activation of the cytokine TGF-ß pathway in various tumor models. Cytokine TGF-ß can preferentially promote single cell motility and blood-borne metastasis and therefore activation of this pathway may explain the enhanced bone marrow metastasis observed in this animal model.

Expression of brain-derived neurotrophic factor and tropomyosin-related kinase-B in a bovine jejunal nodular ganglioneuroblastoma.

This report describes the morphologic, ultrastructural, and immunophenotypic features of a nodular ganglioneuroblastoma in the jejunum of a 13-month-old Holstein-Friesian heifer. On histologic examination, the mass was composed of clusters of neuroblasts and isolated ganglionic neurons in abundant neurophilic matrix that was surrounded by scanty Schwannian stroma. On ultrastructure examination, the large ganglionic neuron-like cells had unmyelinated neurites. Most ganglionic neuron-like tumor cells expressed neurofilament, neuron-specific enolase, chromogranin A, and S-100, whereas the Schwann-cell-like stromal cells expressed S-100 and vimentin. Both brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase-B (Trk-B) were expressed in ganglionic neuron-like tumor cells, which suggested the activation or reactivation of an embryonic autocrine BDNF/Trk-B pathway that could have prolonged cell survival and promoted differentiation with neurite formation.

DNA-topoisomerase I, a new target for the treatment of neuroblastoma.

DNA-topoisomerase I is the nuclear target of new anticancer drugs, namely camptothecin and its derivatives. In order to establish the rational basis for their clinical development in paediatric oncology, the antitumour activity of irinotecan (CPT-11) and topotecan, two camptothecin water-soluble derivatives, was studied in nude mice bearing neuroblastoma xenografts. The panel was composed of 4 previously established subcutaneous xenograft lines (IGR-N835, IGR-N91, IGR-NB3, IGR-NB8) that exhibited the common biological markers of poor prognosis in children (MYCN amplification, 1p deletion, paradiploidy and/or MDR1 overexpression). Irinotecan and topotecan were administered i.v. or i.p. over 5 consecutive days in animals bearing tumours. Irinotecan (40 mg/kg/day) induced 20-100% complete regressions with tumour growth delays ranging from 20 to 46 days. Two out of 10 IGR-N91 bearing animals were tumour free more than 120 days after treatment with the top dose (50 mg/kg/day). Topotecan (2.7 mg/kg/day) induced 0-67% complete regressions with tumour growth delays ranging from 23 to 50 days. One out of 8 IGR-NB3 bearing mice was tumour free at the end of the experiment. The antitumour activity of both drugs was clearly sustained at a lower dose level. Topoisomerase I activity was assayed in 15 neuroblastomas, 3 ganglioneuroblastomas and 2 normal adrenal glands, using a DNA relaxation assay. Topoisomerase I activity ranged from 69 to 1304 arbitrary units/mg of protein, and was significantly higher in immature neuroblastomas than in ganglioneuroblastomas and adrenal glands. In conclusion, irinotecan and topotecan are active against neuroblastoma xenografts. Their target is expressed in patients' tumour samples. Clinical development of topoisomerase I inhibitors in children with neuroblastoma is warranted.

Biological variables in thoracic neuroblastoma: a Pediatric Oncology Group study.

The prognosis for patients with neuroblastoma is related to the age and stage at time of presentation, as well as to the presence or absence of biological markers such as N-myc amplification and the degree of DNA ploidy. However, previous studies have shown that neuroblastoma in the thoracic site also is a favorable prognostic indicator, in that children with mediastinal neuroblastoma have a better survival rate, regardless of age or stage at time of presentation. This study was designed to evaluate the biological differences between thoracic and nonthoracic neuroblastoma with respect to N-myc amplification, DNA index as a measure of DNA ploidy, serum lactate dehydrogenase levels, and serum ferritin levels. Patients enrolled in the Pediatric Oncology Group study protocols for neuroblastoma were evaluated retrospectively, and log-rank analysis allowed the impact of each biological variable on survival to be determined for each cohort of patients. There were 1,335 neuroblastoma patients in the data base; 227 had thoracic-site neuroblastoma. Through analysis, it was apparent that patients with thoracic neuroblastoma have better survival rates than do their nonthoracic counterparts (P < .0001), and they are less likely to have N-myc amplification (P = .001), more likely to have an LDH level of less than 1,500 (P < .0001), and usually have a DNA index of greater than 1 (P < .003). Both thoracic and nonthoracic patients have low serum ferritin levels (86% of thoracic versus 83% of nonthoracic patients).(ABSTRACT TRUNCATED AT 250 WORDS)