Kwang Chul Lee

Use of RNA interference to elucidate the effect of MYCN on cell cycle in neuroblastoma

MYCN amplification marks poor prognosis in neuroblastoma (NB) tumors. In evaluating the mechanisms by which retinoic acid (RA) or nerve growth factor (NGF) decrease cell number in MYCN amplified NB cells, we have identified a number of proteins whose expression either decreases (E2F, CDC2, CDK6, cyclin dependent kinase activity) or increases (p27) in association with a decrease in MYCN expression. However, it was still unclear which were MYCN dependent effects or not.

Clinical features and treatment outcomes of Langerhans cell histiocytosis: a nationwide survey from Korea histiocytosis working party.

A nationwide survey was conducted to clarify the clinical features and outcomes of Korean children with Langerhans cell histiocytosis (LCH). Korea Histiocytosis Working Party analyzed the data of 603 patients who were diagnosed with LCH between 1986 and 2010 from 28 institutions in Korea. Median age at diagnosis was 65 months (range, 0 to 276 mo). Bone was the most frequently affected organ (79.6%) followed by skin (19.2%). Initially, 419 patients (69.5%) had single-system involvement (SS), 85 (14.1%) with multisystem (MS) disease without risk organ involvement (MS-RO−), and 99 (16.4%) multisystem disease with risk organ involvement (MS-RO+). The 5-year overall survival (OS) rates in the SS, MS-RO−, and MS-RO+ groups were 99.8%, 98.4%, and 77.0%, respectively (P<0.001), and the 5-year reactivation rates were 17.9%, 33.5%, and 34.3%, respectively (P<0.001). The OS rate was lower in patients with RO involvement (P=0.025) and lack of response to initial treatment (P=0.001). MS involvement (P=0.036) was an independent risk factor for reactivation. Permanent consequences were documented in 99 patients (16.4%). Reactivation of disease, MS involvement, and age at diagnosis ⩽2 years were associated with higher incidence of permanent consequences. This study emphasized that further efforts are required to improve survival of MS-RO+ patients and reduce reactivation in younger patients with MS involvement.

Recombinant urate oxidase (Rasburicase) for the treatment of hyperuricemia in pediatric patients with hematologic malignancies: Results of a compassionate prospective multicenter study in Korea†

Hyperuricemia accompanying tumor lysis syndrome is a serious complication in neoplasia with rapid proliferation and destruction. To confirm the efficacy of recombinant urate oxidase (rasburicase) and its safety profile, a phase IV compassionate use prospective study was performed in Korean pediatric patients with hematologic malignancies.

Regulation of bcl-2 family in hydrogen peroxide-induced apoptosis in human leukemia HL-60 cells

Numerous types of cells have been shown to undergo apoptosis when exposed to oxidant agent such as hydrogen peroxide. In order to understand the functional relationship between the anti- and pro-apoptotic regulatory proteins in the cells under oxidant stress, we have studied the level of expression of apoptosis regulatory proteins, bcl-2 and bax, in human leukemia HL-60 cells. The exposure of HL-60 cells to different concentrations of H2O2 for 6 h resulted in a typical apoptosis of the cells as characterized by flow cytometry, cell cycle analysis, and DNA fragmantation. There was a block in G1 to S transition and apoptotic cells were mainly derived from S and G2 cells. Kinetic study demonstrated that the levels of both bcl-2-mRNA and -protein expression were decreased with the progression of cellular apoptosis whereas the level of bax-mRNA was unchanged but the expressed bax-protein was not detectable. Cycloheximide, a nonspecific translation inhibitor, did not prevent the hydrogen peroxide-mediated apoptosis in HL-60 cells. These results suggest that the regulation of bcl-2, but not of bax are important factor in the oxidative stress-induced apoptosis in HL-60 cells.

Increased Serum Interleukin-5 and Vascular Endothelial Growth Factor in Children With Acute Mycoplasma Pneumonia and Wheeze

Acute mycoplasma pneumonia may be accompanied by wheeze in some children considered not to have asthma. The aim of the present study was to evaluate cytokine secretion in children with acute mycoplasma pneumonia and wheeze. We studied 58 patients with mycoplasma pneumonia (12 with wheeze, Group 1; 46 without wheeze, Group 2) and 36 patients of non‐mycoplasma pneumonia (Group 3). Serum levels of interleukin (IL)‐4, IL‐5, interferon (IFN)‐γ, and vascular endothelial growth factor (VEGF) were measured using an enzyme‐linked immunosorbent assay kits. The mean ± SD IL‐5 level of Group 1 was 97.1 ± 73.0 pg/ml, which was significantly higher than that of Group 2 (28.2 ± 32.2 pg/ml) and that of Group 3 (35.7 ± 42.0 pg/ml). The mean ± SD VEGF level of Group 1 was 687.5 ± 385.8 pg/ml, which was significantly higher than that of Group 2 (310.0 ± 251.9 pg/ml) and that of Group 3 (402.3 ± 279.5 pg/ml). No significant differences in serum levels of IL‐4, IFN‐γ, and IgE were observed between the groups. Our results show that children with mycoplasma pneumonia and wheeze have significantly higher serum levels of IL‐5 and VEGF. These increased immune responses may be associated with the pathophysiological mechanisms by which the Mycoplasma pneumoniae contribute to the development of wheeze during acute mycoplasma pneumonia. Pediatr Pulmonol. 2009; 44:423–428.

Epidemiology and clinical long-term outcome of childhood aplastic anemia in Korea for 15 years: retrospective study of the Korean Society of Pediatric Hematology Oncology (KSPHO).

Purpose Aplastic anemia (AA) is a rare hematologic disease characterized by pancytopenia and hypocellular marrow. The Korean Society of Pediatric Hematology Oncology investigated retrospectively the incidence, survival, and transfusion independency according to treatment strategies in AA. Methods All the questionnaires were sent to members for medical records. We collected and analyzed 702 available data. Results The male and female ratio was 1.2, and the median age at diagnosis was 9.3 years. The annual incidence of Korean children with AA was 5.16 per million per year. Constitutional anemia was diagnosed in 44 children. In acquired AA, causes were identified in 39 children. Severe AA (SAA) at initial diagnosis was more common than nonsevere AA. The overall survival was 47.8% with supportive care, 68.1% with immunosuppressive therapy (IST), and 81.8% with hematopoietic stem cell transplantation. In IST, response rate was 65.7%, and relapse rate after response was 54.4% within a median of 23.0 months. The factors with overall survival were severity of disease in supportive care, severity and response in IST, donor type, graft failure, and posttransplant events in hematopoietic stem cell transplantation. Conclusions Long-term outcome in AA was dependent on treatment strategies. These Korean results may help research and prospective international clinical trials for childhood AA.

Alteration of CD4+CD25+Foxp3+ T cell level in Kawasaki disease

Purpose Exaggerated pro-inflammatory reactions during the acute phase of Kawasaki disease (KD) suggest the role of immune dysregulation in the pathogenesis of KD. We investigated the profiles of T regulatory cells and their correlation with the clinical course of KD. Methods Peripheral blood mononuclear cells were collected from 17 KD patients during acute febrile and subacute afebrile phases. T cells expressing CD4, CD25, and Foxp3 were analyzed using flow cytometry, and the results were correlated with the clinical course of KD. Results The percentage of circulating CD4+CD25highFoxp3+ T cells among CD4+ T cells was significantly higher during the subacute afebrile phase than during the acute febrile phase (1.10%±1.22% vs. 0.55%±0.53%, P=0.049). Although levels of CD4+CD25lowFoxp3+ T cells and CD4+CD25-Foxp3+ T cells were only slightly altered, the percentage of CD4+CD25+Foxp3- T cells among CD4+ T cells was significantly lower during the subacute afebrile phase than during the acute febrile phase (2.96%±1.95% vs. 5.64%±5.69%, P=0.036). Consequently, the ratio of CD25highFoxp3+ T cells to CD25+Foxp3- T cells was higher during the subacute afebrile phase than during the acute febrile phase (0.45%±0.57% vs. 0.13%±0.13%, P=0.038). Conclusion Decreased CD4+CD25highFoxp3+ T cells and/or an imbalanced ratio of CD4+CD25highFoxp3+ T cells to CD4+CD25+Foxp3- T cells might play a role in KD development. Considering that all KD patients were treated with intravenous immunoglobulin (IVIG), recovery of CD4+CD25highFoxp3+ T cells during the subacute afebrile phase could be a mechanism of IVIG.

Idiopathic acute eosinophilic pneumonia in a 14-month-old girl

Idiopathic acute eosinophilic pneumonia (IAEP), characterized by acute febrile respiratory failure associated with diffuse radiographic infiltrates and pulmonary eosinophilia, is rarely reported in children. Diagnosis is based on an association of characteristic features including acute respiratory failure with fever, bilateral infiltrates on the chest X-ray, severe hypoxemia and bronchoalveolar lavage fluid >25% eosinophils or a predominant eosinophilic infiltrate in lung biopsies in the absence of any identifiable etiology. We present a 14-month-old girl who was admitted to our pediatric intensive care unit because of acute respiratory distress. She had a fever, dry cough, and progressive dyspnea for 1 day. Chest X-ray showed multifocal consolidations, increased interstitial markings, parenchymal emphysema and pneumothorax. IAEP was confirmed by marked pulmonary infiltrates of eosinophils in the lung biopsy specimen. Most known causes of acute eosinophilic pneumonia, such as exposure to causative drugs, toxins, second-hand smoking and infections were excluded. Her symptoms were resolved quickly after corticosteroid therapy.

Quantitative Comparison of CDKN2B Methylation in Pediatric and Adult Myelodysplastic Syndromes

Background/Aims: Transcriptional repression of tumor suppressor genes is determined by the quantity of promoter hypermethylation. We analyzed the methylation quantity of CDKN2B in pediatric myelodysplastic syndromes (MDS). Methods: Quantitative measurement of CDKN2B methylation was performed in 25 pediatric MDS patients and 12 controls using pyrosequencing, and the result was compared with those from 74 adult MDS cases and 31 adult controls. The association between CDKN2B methylation quantity and factors related to prognosis including bone marrow blast percentage and karyotype was analyzed. Results: Pediatric MDS patients showed a higher methylation level (MtL) of CDKN2B than pediatric controls (2.94 vs. 1.62; p = 0.031) but a lower level than adult MDS patients (8.76; p < 0.001). MtL was higher in pediatric MDS cases with >5% blasts than in pediatric controls (3.78 vs. 1.62; p = 0.052). Pediatric MDS cases with abnormal karyotype showed a higher MtL than pediatric controls (5.95 vs. 1.62; p = 0.045). Conclusions: We confirmed that methylation of CDKN2B is associated with the pathogenesis and prognosis in pediatric MDS. The difference in MtLs between pediatric and adult MDS might be related to the physiological hypermethylation of tumor suppressor genes in aging.

Characteristics and Outcomes of Second Malignant Neoplasms after Childhood Cancer Treatment: Multi-Center Retrospective Survey

This retrospective study investigated the clinical characteristics and outcomes of second malignant neoplasms (SMNs) in survivors of childhood cancer from multiple institutions in Korea. A total of 102 patients from 11 institutions who developed SMN after childhood cancer treatment between 1998 and 2011 were retrospectively enrolled. The most common primary malignant neoplasms (PMNs) were central nervous system (CNS) tumors (n = 17), followed by acute lymphoblastic leukemia (n = 16), non-Hodgkin lymphoma (n = 13), and osteosarcoma (n = 12). The most common SMNs were therapy-related myeloid neoplasms (t-MNs; acute myeloid leukemia [AML], 29 cases; myelodysplastic syndrome [MDS], 12 cases), followed by thyroid carcinomas (n = 15) and CNS tumors (n = 10). The median latency period was 4.9 years (range, 0.5–18.5 years). Among 45 patients with solid tumors defined as an SMN, 15 (33%) developed the lesion in a field previously subjected to radiation. The 5-year overall survival (OS) rate of patients with an SMN was 45% with a median follow-up time of 8.6 years. Patients with AML, MDS, and CNS tumors exhibited the poorest outcomes with 5-year OS rates of 18%, 33%, and 32%, respectively, whereas those with second osteosarcoma showed comparable outcomes (64%) to patients with primary counterpart and those with second thyroid carcinoma had a 100% OS rate. Further therapeutic efforts are recommended to improve the survival outcomes in patients with SMNs, especially in cases with t-MNs and CNS tumors.