Identification of new genes related to the myogenic differentiation arrest of human rhabdomyosarcoma cells.

Rhabdomyosarcoma is a soft tissue tumor committed to the myogenic lineage but arrested prior to terminal differentiation. To identify new genes implicated in the block in myogenic differentiation of rhabdomyosarcoma cells and those responsible for their proceeding along the myogenic pathway we used cDNA microarrays to compare gene expression profiles of two clones of the human embryonal rhabdomyosarcoma cell line RD with different myogenic potentials: RD/12, which is unable to differentiate, and RD/18, which shows elements able to terminally differentiate, as defined by the expression of myosin heavy chain (up to 50% of the population) and the formation of multinucleated myotube-like structures. We identified 80 genes differentially expressed by the two clones. Differentiating RD/18 cells overexpressed the myogenic transcription factor myogenin along with known myogenic markers; myogenin transfection into undifferentiated RD/12 cells was able to revert the phenotype giving rise to 94% of clones displaying a differentiated morphology. RD/18 cells also expressed several genes not known to be expressed in rhabdomyosarcoma or muscle cells, such as pigment-epithelium derived factor and endothelin-3. Poorly differentiated RD/12 cells, along with genes related to mesenchymal lineage or early myogenic commitment, also expressed genes not previously known to be related to the differentiation block of human rhabdomyosarcoma, such as monocyte chemotactic protein-1, connective tissue growth factor and insulin-like growth factor binding protein-5. Differential expression of these genes in a time course of differentiation suggested their potential roles as either new myogenic markers or repressors of differentiation. These results identify a cluster of new genes related to the aberrant myogenic differentiation program of human rhabdomyosarcoma cells.

Gefitinib in patients with progressive high-grade gliomas: a multicentre phase II study by Gruppo Italiano Cooperativo di Neuro-Oncologia (GICNO).

To investigate the role of gefitinib in patients with high-grade gliomas (HGGs), a phase II trial (1839IL/0116) was conducted in patients with disease recurrence following surgery plus radiotherapy and first-line chemotherapy. Adult patients with histologically confirmed recurrent HGGs following surgery, radiotherapy and first-line chemotherapy, were considered eligible. Patients were treated with gefitinib (250 mg day(-1)) continuously until disease progression. The primary end point was progression-free survival at 6 months progression-free survival at 6 months (PFS-6). Tissue biomarkers (epidermal growth factor receptor (EGFR) gene status and expression, phosphorylated Akt (p-Akt) expression) were assessed. Twenty-eight patients (median age, 55 years; median ECOG performance status, 1) were enrolled; all were evaluable for drug activity and safety. Sixteen patients had glioblastoma, three patients had anaplastic oligodendrogliomas and nine patients had anaplastic astrocytoma. Five patients (17.9%, 95% CI 6.1-36.9%) showed disease stabilisation. The overall median time to progression was 8.4 (range 2-104+) weeks and PFS-6 was 14.3% (95% CI 4.0-32.7%). The median overall survival was 24.6 weeks (range 4-104+). No grade 3-4 gefitinib-related toxicity was found. Gefitinib showed limited activity in patients affected by HGGs. Epidermal growth factor receptor expression or gene status, and p-Akt expression do not seem to predict activity of this drug.

Is protracted low-dose temozolomide feasible in glioma patients?

The authors investigated the safety of 75 mg/m2 temozolomide for 21 days every 28 days in glioma patients. This schedule could lead to DNA repair enzyme O6-alkylguanine-DNA alkyltransferase depletion, contributing to overcoming drug resistance. Although Phase III studies are forthcoming, no data are available on the long-term toxicity of temozolomide, which, in this series, incurred prolonged, cumulative lymphopenia, which leads to a high incidence of infections.

Phase II trial of carboplatin and etoposide for patients with recurrent high-grade glioma.

We present the results of a phase II trial of carboplatin and etoposide (CE) combination as first-line chemotherapy in patients with recurrent glioblastoma multiforme (GBM) and anaplastic astrocytoma (AA) after surgery and radiotherapy. We assess the activity and the tolerability of this combination. 30 patients with GBM (25) and AA (5) were treated with VP-16 (etoposide) 120 mg m(-2) and CBCDA (carboplatin) 100 mg m(-2) for 3 days every 4 weeks. Moreover, we performed a retrospective analysis of topoisomerase IIalpha gene status using chromogenic in situ hybridisation. The median age was 54 years (21-73 years); Eastern Cooperative Oncology Group performance score was 0-1 in 25 patients and 2 in five patients. All patients had been previously treated with surgical resection (21 radical resections) followed by radiation therapy (40-60 Gy). We observed six (20%) complete responses, three (10%) partial responses and 12 (40%) stable diseases, with a response rate of 30%. The median time to progression was 4 months, while progression-free survival at 6 months was 33.3%. The median survival time was 10 months. Neutropenia occurred in 9 patients: four patients had grade 4, two patients grade 3 and three patients grade 2. In the conclusion of this clinical trial, the CE combination has shown activity in recurrent GBM and AA, with a good toxicity profile. Alterations in the copy number of topoisomerase IIalpha gene seem to be a rare event and in our series do not influence response to the CE combination.

The metastatic ability of Ewing's sarcoma cells is modulated by stem cell factor and by its receptor c-kit.

Ewing's sarcoma is a primitive highly malignant tumor of bone and soft tissues usually metastasizing to bone, bone marrow, and lung. Growth factor receptors and their ligands may be involved in its growth and dissemination. We analyzed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of six Ewing's sarcoma cell lines. All cell lines exhibited substantial levels of surface c-kit expression, and five of six displayed transmembrane SCF on the cell surface. Expression of c-kit was down-modulated in all lines by exposure to exogenous SCF. The SCF treatment was able to confer to cells a growth advantage in vitro, due both to an increase in cell proliferation and to a reduction in the apoptotic rate. When used in the lower compartment of a migration chamber, SCF acted as a strong chemoattractant for Ewing's sarcoma cells. The pretreatment of cells with SCF reduced their chemotactic response to SCF. In athymic nude mice, Ewing's sarcoma cells injected intravenously metastasized to the lung and to a variety of extrapulmonary sites, including bone and bone marrow. Metastatic sites resembled those observed in Ewing's sarcoma patients and corresponded to SCF-rich microenvironments. The in vitro pretreatment of cells with SCF strongly reduced the metastatic ability of Ewing's sarcoma cells, both to the lung and to extrapulmonary sites. This could be dependent on the down-modulation of c-kit expression observed in SCF-pretreated cells, leading to a reduced sensitivity to the chemotactic and proliferative actions of SCF. Our results indicate that the response to SCF mediated by c-kit may be involved in growth, migration, and metastatic ability of Ewing's sarcoma cells.