Expression of the multidrug resistance-associated protein (MRP) gene correlates with amplification and overexpression of the N-myc oncogene in childhood neuroblastoma.

The MRP gene (Cole et al., Science (Washington DC), 258: 1650-1654, 1992) encodes a membrane-bound glycoprotein the expression of which correlates with non-P-glycoprotein-mediated multidrug resistance in a variety of cultured human cell lines. Using an RNA-polymerase chain reaction assay, expression of this gene was examined in the highly chemoresistant pediatric malignancy, neuroblastoma.

Regulation of retinoic acid receptor alpha expression in human neuroblastoma cell lines and tumor tissue.

Human neuroblastoma (NB) cell lines treated with all-trans retinoic acid (RA) differentiate in culture, forming neurites and exhibiting growth arrest. We treated 5 human NB cell lines with RA, and observed a 2-5 fold induction of retinoic acid receptor alpha (RAR alpha) mRNA expression in 4 of the 5 cell lines, as an early cellular response. Induction of RAR alpha expression was specific for RA among several differentiating agents tested.

Determination of N-myc gene amplification in neuroblastoma by differential polymerase chain reaction.

Determination of N-myc gene amplification, a powerful prognostic indicator in the childhood tumour, neuroblastoma, has routinely been performed by Southern analysis. We have developed a differential polymerase chain reaction (PCR) assay, in which the N-myc target gene is co-amplified with a control gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Following electrophoresis, a ratio between the two PCR products within a given DNA sample is then determined by densitometry.

Characterization of sarcoma cell lines from v-jun transgenic mice.

Wounding is a prerequisite for tumor formation in v-jun transgenic mice. The progression from wound to dermal sarcoma is a multistep process which, at some stage, results in an increase in transgene mRNA expression in tumor tissue. However, transgene expression in individual sarcoma cells stained for Jun protein cultures is heterogeneous.

Tumor necrosis factor alpha and interleukin 1 alpha induce anchorage independence in v-jun transgenic murine cells.

The oncogene jun encodes a transcription factor of the AP-1 family. In mice carrying viral jun (v-jun) as a transgene, wounding is a prerequisite for tumorigenesis, suggesting collaboration between the transgene and a wound-related event. To define possible candidates for this collaborative process, we examined the effect of several wound-related polypeptide growth factors on cells from transgenic mice.

Wounding acts as a tumor promoter in chickens inoculated with avian sarcoma virus 17.

Avian sarcoma virus 17 (ASV17) is an acutely transforming retrovirus which carries the oncogene v-jun. The virus induces fibrosarcomas in chickens at the site of inoculation. Here we describe wound-related tumor formation in 77% of chickens inoculated with ASV17 in one wing and wounded by metal clip insertion in the opposite wing.

Heterotransplantation of human lymphoid neoplasms using a nude mouse intraocular xenograft model.

There are few effective models for the study of human lymphoid neoplasms, including in vivo xenografts in immunocompromised animals. Exploiting the additional immune privilege of the anterior chamber of the nude mouse eye, a novel method of direct heterotransplantation of cells from childhood leukemias and lymphomas has been developed. The establishment and characterization of 18 lymphoid xenograft cell lines maintained in the nude mouse intraocular model are reported.

In vitro effect of acetaldehyde on cell-mediated cytotoxicity by murine spleen cells.

The effects of acetaldehyde in vitro on the lytic capacity of murine spleen cells have been evaluated in three systems: antibody-dependent cell-mediated cytotoxicity (ADCC), natural killer (NK) activity, and alloimmune cytotoxic T lymphocyte (CTL) activity. Acetaldehyde had a biphasic effect on ADCC. Concentrations less than 1 mM acetaldehyde potentiated ADCC.

Effective therapy for a severe case of the idiopathic hypereosinophilic syndrome.

An 8-year-old boy with idiopathic hypereosinophilic syndrome (HES) is reported. He has been maintained in prolonged hematologic remission with vincristine and mercaptopurine despite an initial eosinophil count of 186 X 10(9)/L and a poor response to prednisone and hydroxyurea. Success with this combination of chemotherapeutic agents has not previously been reported in the management of HES.

The effect of neuraminidase on the molecular weight and the isoelectric point of the steroid induced alkaline phosphatase of dogs.

Isoelectric focusing and gradient polyacrylamide gel electrophoresis were used to define the physical differences between canine liver alkaline phosphatase (LAP) and steroid induced alkaline phosphatase (SIAP). LAP has an isoelectric point (pI) of pH 4.3 and a molecular radius (Mr) of 100,000, while SIAP has a pI of pH 3.