Neuroblastoma is a common tumor in childhood and exhibits heterogeneity and malignant progression. MYCN expression and amplification profiles are frequently correlated with the efficacy of therapy. Arsenic trioxide and imatinib mesylate (STI-571) have been suggested as promising therapeutic agents for neuroblastoma, which has been shown to be resistant to conventional therapy. In order to ascertain whether the combination of arsenic trioxide and STI-571 exerts a synergistic cytotoxic effect on neuroblastoma cells in relation to MYCN status, we evaluated cellular proliferation after 72 h of exposure to arsenic trioxide and STI-571 with or without siRNA against MYCN in SH-SY5Y, SK-N-SH and SK-N-BE(2) neuroblastoma cells. Arsenic trioxide and STI-571 demonstrated a synergistic inhibitory effect on cellular proliferation, while MYCN knockdown had an antagonistic effect on this combined treatment. These results indicate that STI-571 treatment may prove effective for MYCN-expressing or MYCN-amplified neuroblastoma. Furthermore, siRNA therapy targeted to MYCN should be avoided in combination with STI-571 treatment in cases of neuroblastoma.

Purpose

Neuroblastoma is a common tumor in childhood, and generally exhibits heterogeneity and a malignant progression. MYCN expression and amplification profiles frequently correlate with therapeutic prognosis. Although it has been reported that MYCN silencing causes differentiation and apoptosis in human neuroblastoma cells, MYCN expression influences the cytotoxic potential of chemotherapeutic drugs via the deregulation of the cell cycle. STI-571 may constitute a promising therapeutic agent against neuroblastoma, particularly in cases in which c-Kit is expressed preferentially in MYCN-amplified neuroblastoma.

Materials and Methods

To determine whether STI-571 exerts a synergistic effect on cytotoxicity with MYCN expression, we assessed apoptotic cell death and cell cycle distribution after 72 h of exposure to STI-571 with or with out treatment of SK-N-BE(2) neuroblastoma cells with MYCN siRNA.

Results

MYCN siRNA-treated SK-N-BE(2) cells did not affect apoptosis and cells were arrested in G0/G1 phase after STI-571 treatment.

Conclusions

siRNA therapy targeted to MYCN may not be effective when administered in combination with STI-571 treatment in cases of neuroblastoma. Therefore, chemotherapeutic drugs that target S or G2-M phase may prove ineffective when applied to cells arrested in the G0/1 phase as the result of MYCN knockdown and STI-571 treatment.

Bcr-abl antisense oligodeoxynucleotides (AS-ODNs) have provided evidence of an antileukemia effect when tested in vitro against Philadelphia-positive cells. In order to investigate the efficacy of AS-ODNs as purging agents in chronic myeloid leukemia (CML) patients, K562 cells, a human CML cell line, were treated in vitro with various types of AS-ODNs and interferon-alpha. Cells were treated in vitro for 0 and 36 hr with 40 microgram/mL of AS-ODNs, respectively, and incubated at 37 degrees C for 36 hr. Cytotoxic effects were measured by counting the number of viable cells as well as by MTT test. Clonogenic activities were evaluated by methylcellulose culture for 2 weeks. The effects of purging agents on the rearrangement of bcrabl gene were evaluated by RT-PCR. AS-ODNs inhibited the proliferation of K562 cells with time in cell count assay and MTT test. AS-ODNs were superior to INF-alpha in inhibiting clonogenic activity (recovery rate; 26.3% vs 64.0%). After incubation with bcr-abl AS-ODNs primers and mRNA isolated from K562 cells, positive bands were abolished, especially of b3a2 type and phosphorothioate type. Our results suggest that AS-ODNs mediated purging may be one of the efficient methods and that autograft may be an alternative treatment for allograft in high-risk group patients of CML if they do not have a stem cell donor.

Autologous stem cell transplantation (ASCT) for the treatment of high-risk neuroblastoma (NBL) is an accepted method for restoring bone marrow depression after high dose chemotherapy. We retrospectively analyzed eighty eight cases of NBL that underwent ASCT following marrow ablative therapy at 12 transplant centers of the Korean Society of Pediatric Hematology-Oncology between January 1996 and September 2000. Seventy nine children were of stage IV NBL and 9 were of stage III with N-myc amplification. Various cytoreductive regimens were used. However, the main regimen was 'CEM' consisting of carboplatin, etoposide and melphalan, and this was used in 66 patients. Total body irradiation was also added in 36 patients for myeloablation. To reduce tumor cell contamination, stem cell infusions after CD34+ cell selection were performed in 16 patients. Post-transplantation therapies included the second transplantation in 18 patients, interleukin2 therapy in 45, 13-cis retinoic acid in 40, 131-meta-iodobenzylguanidine in 4, conventional chemotherapy in 11, and local radiotherapy in 8. Twenty two patients died, sixty six patients are surviving 1 to 46 months after ASCT (median followup duration, 14.5 months). Although the follow-up period was short and the number of patients small, we believe that ASCT might improve the survival rate in high-risk NBL.

Background

Diamond Blackfan anemia (DBA), characterized by impaired red cell production, is a rare condition that is usually symptomatic in early infancy. The purpose of this study was to assess nationwide experiences of DBA encountered over a period of 20 years.

Methods

The medical records of 56 patients diagnosed with DBA were retrospectively reviewed from November 1984 to July 2010. Fifteen institutions, including 13 university hospitals, participated in this study.

Results

The male-to-female ratio of patients with DBA was 1.67:1. The median age of diagnosis was 4 months, and 74.1% were diagnosed before 1 year of age. From 2000 to 2009, annual incidence was 6.6 cases per million. Excluding growth retardation, 38.2% showed congenital defects: thumb deformities, ptosis, coarctation of aorta, ventricular septal defect, strabismus, etc. The mean hemoglobin concentration was 5.1±1.9 g/dL, mean corpuscular volume was 93.4±11.6 fL, and mean number of reticulocytes was 19,700/mm3. The mean cellularity of bone marrow was 75%, with myeloid:erythroid ratio of 20.4:1. After remission, 48.9% of patients did not need further steroids. Five patients with DBA who received hematopoietic transplantation have survived. Cancer developed in 2 cases (3.6%).

Conclusion

The incidence of DBA is similar to data already published, but our study had a male predilection. Although all patients responded to initial treatment with steroids, about half needed further steroids after remission. It is necessary to collect further data, including information regarding management pathways, from nationwide DBA registries, along with data on molecular analyses.