Peripheral Neuroectodermal Tumor Cell Research Articles

Effects of all-trans retinoic acid and interferon alpha in peripheral neuroectodermal tumor cell cultures and xenografts.

Peripheral neuroectodermal tumors (PNET) have an unsatisfactory outcome when treated with standard approaches. Among novel treatments, the use of biological response modifiers has rarely been reported in this group of malignancies. We have previously demonstrated that both all-trans retinoic acid (ATRA) and interferon á (IFNá) can inhibit proliferation of human PNET cells and that ATRA can up-regulate IFNá receptor expression in vitro. In this study we evaluated the anti-tumor effects of ATRA and IFNá in PNET cells in vitro and in a human PNET xenograft model, using CHP100 cells. A synergistic inhibitory effect of ATRA and IFNá was observed on CHP100 cells in vitro. On the contrary, a significant inhibition of tumor growth was observed in mice treated with ATRA alone, whereas neither IFNá nor the combination of ATRA and IFNá, reached a statistically significant anti-tumor effect. Histologic examination of tumors revealed the presence of necrosis upon treatment with IFNá, whereas almost no necrosis, but a more differentiated morphology, confirmed by electron microscopy analysis, was associated with the ATRA containing treatments. Taken together these data show an in vitro and in vivo anti-tumor activity of ATRA in human PNET cells, although no synergism of ATRA and IFNá was observed in our xenograft model.

Expression of PAX3 in Ewing's Sarcoma Family of Tumors

The Ewing's sarcoma family of tumors (ESFT) is the second most common pediatric malignancy originating in the bone and is characterized by the t(11; 22) translocation. PAX3, a member of the paired box family of genes, is expressed during embryonal development of neural crest cells and is involved in the t(2; 13) translocation found in alveolar rhabdomyosarcoma. Since ESFTs are believed to be derived from neural crest tissue, we screened a series of Ewing's sarcoma and peripheral neuroectodermal tumor cell lines and tumor specimens for expression of PAX3. We found expression of PAX3 in most, but not all, of the specimens analyzed, including cell lines and patient material.

Detection of recurrent chromosome abnormalities in Ewing's sarcoma and peripheral neuroectodermal tumor cells using bivariate flow karyotyping.

Bivariate flow karyotyping can be used for the detection of recurrent chromosome abnormalities in tumor cells. For this purpose 2 cell lines originally derived from Ewing's sarcomas and 4 cell lines from peripheral neuroectodermal tumors were used. The characteristic t(11;22) was known to be present in 5 cell lines. The remaining cell line was known to have a variant t(2;11;22;21) translocation. Metaphase chromosomes were stained with the fluorescent dyes Hoechst 33258 and Chromomycin A3 and analyzed subsequently using bivariate flow cytometry. The resulting bivariate flow karyotypes of the tumor cells were normalized by a standardized procedure using a computerized method and compared with a reference flow karyotype of normal chromosomes. In 5 cell lines two recurring abnormal chromosome peaks were identified at positions expected for the der(11) and der(22) chromosomes characteristic for the reciprocal t(11;22)(q24;q12). In the remaining cell line with the variant t(2;11;22;21), only the peak representing the der(22) was identifiable. It is concluded that bivariate flow karyotyping can be used for the semiautomated detection of recurrent translocations and the assessment of their variability among different tumors.

A New Human Highly Tumorigenic Neuroblastoma Cell Line with Undetectable Expression of N-myc

A peculiar human cell line (GI-ME-N) derived from the metastatic bone marrow of a 2-yr-old patient with stage IV neuroblastoma (NB) was extensively characterized. Cell-type-specific markers, tumorigenicity in nude mice, morphology, cytogenetics, and amplification/expression of the N-myc gene were evaluated. All metaphases presented the typical 1p deletion. Surface markers specific for NB cells, vimentin, and neurofilament proteins were all clearly detectable with immunofluorescence and/or western blot procedures. Moreover, it was found that GI-ME-N cells did not express N-myc oncogene or HLA class 1 antigens, and were not classified as peripheral neuroectodermal tumor cells. However, extremely short latency and survival times, comparable to peripheral neuroectodermal tumor cells, were observed in nude mice grafted with GI-ME-N. In addition, no correlations were observed in tumorigenicity of N-myc amplified (IMR32) versus unamplified (SK-N-SH GI-ME-N) human NB cell lines in nude mice. We conclude that N-myc amplification/expression do not correlate with the aggressiveness of human NB in athymic animals, which is not always explained by the peripheral neuroectodermal tumor cell nature of the malignant cells, either.