Off-target function of the Sonic hedgehog inhibitor cyclopamine in mediating apoptosis via nitric oxide-dependent neutral sphingomyelinase 2/ceramide induction.

Sonic hedgehog (SHh) signaling is important in the pathogenesis of various human cancers, such as medulloblastomas, and it has been identified as a valid target for anticancer therapeutics. The SHh inhibitor cyclopamine induces apoptosis. The bioactive sphingolipid ceramide mediates cell death in response to various chemotherapeutic agents; however, ceramide's roles/mechanisms in cyclopamine-induced apoptosis are unknown. Here, we report that cyclopamine mediates ceramide generation selectively via induction of neutral sphingomyelin phosphodiesterase 3, SMPD3 (nSMase2) in Daoy human medulloblastoma cells. Importantly, short interfering RNA-mediated knockdown of nSMase2 prevented cyclopamine-induced ceramide generation and protected Daoy cells from drug-induced apoptosis. Accordingly, ectopic wild-type N-SMase2 caused cell death, compared with controls, which express the catalytically inactive N-SMase2 mutant. Interestingly, knockdown of smoothened (Smo), a target protein for cyclopamine, or Gli1, a downstream signaling transcription factor of Smo, did not affect nSMase2. Mechanistically, our data showed that cyclopamine induced nSMase2 and cell death selectively via increased nitric oxide (NO) generation by neuronal-nitric oxide synthase (n-NOS) induction, in Daoy medulloblastoma, and multiple other human cancer cell lines. Knockdown of n-NOS prevented nSMase2 induction and cell death in response to cyclopamine. Accordingly, N-SMase2 activity-deficient skin fibroblasts isolated from homozygous fro/fro (fragilitas ossium) mice exhibited resistance to NO-induced cell death. Thus, our data suggest a novel off-target function of cyclopamine in inducing apoptosis, at least in part, by n-NOS/NO-dependent induction of N-SMase2/ceramide axis, independent of Smo/Gli inhibition.

Disseminated neuroendocrine carcinoma in a pediatric patient: a rare case and diagnostic challenge.

A previously healthy 16-year-old female presented with 1-month history of fever, cough, extremity pain, left upper quadrant pain, and night sweats. Imaging studies revealed mediastinal lymphadenopathy, lung and liver masses, and bony lesions. Liver and bone marrow biopsies revealed small tumor cells with a high nuclear cytoplasmic ratio, stippled chromatin, and inconspicuous nucleoli surrounded by bands of collagen. Immunohistochemically, the tumor cells were positive for epithelial (epithelial membrane antigen and cytokeratin AE1/AE3) and neuroendocrine markers (chromogranin and synaptophysin), and negative for other antigens tested, including vimentin, desmin, CD99, and WT-1. The morphologic features and immunohistochemical profile was consistent with neuroendocrine carcinoma. Despite several chemotherapeutic regimens, the patient had progressive disease and enrolled in a phase 1 trial. Thorough histopathologic evaluation, including immunohistochemical stains is a crucial component for diagnosing this rare, aggressive tumor in children and adolescents.

Post-hematopoietic stem cell transplant immunization practices in the Pediatric Blood and Marrow Transplant Consortium.

BACKGROUND: A survey of National Marrow Donor Program transplant centers in 1995 demonstrated a wide range of immunization practices in post-hematopoietic stem cell transplant (HSCT) recipients, which led to the 2000 Centers for Disease Control and Prevention (CDC) recommendations for vaccination after HSCT. We surveyed the principal investigators of the Pediatric Blood and Marrow Transplant Consortium (PBMTC) to identify immunization practice patterns after HSCT and assess compliance with the 2000 CDC guidelines. PROCEDURE: Approval was obtained from the Medical University of South Carolina Institutional Review Board. A 33 question survey using surveymonkey.com was distributed by email to principal investigators in the PBMTC. RESULTS: Forty-one (40%) of the 102 pediatric HSCT centers participating in the PBMTC responded. Thirty of the responding centers completed the entire survey. For individual vaccines, compliance with the CDC guidelines ranged from 22% to 93%. Less than 20% of the centers reported schedules consistent with the 2000 CDC recommendations for both allogeneic and autologous HSCT recipients. CONCLUSION: Despite the 2000 CDC guidelines, wide variation in post-HSCT immunization practices still exists. Updated guidelines have been needed, particularly to address the use of the pneumococcal conjugate vaccine. In conjunction with multiple other groups, the CDC recently released new immunization guidelines in October 2009. Additional data are still needed to adequately address the utility of incorporating immunologic parameters with the timing of vaccination after HSCT.

Pancytopenia with myelodysplasia due to copper deficiency.

We present a case of pancytopenia in a 9-month-old infant with total parenteral nutrition (TPN) dependence due to short bowel syndrome. Bone marrow examination revealed left-shifted myeloid maturation, erythroid and myeloid dysplasia with normal iron stores. Serum copper level was 2 microm/dl (normal range 90-190 mcg/dl). After supplementation, copper levels normalized at 143 mcg/dl, and the macrocytic anemia, neutropenia, and thrombocytopenia resolved. Copper deficiency should be considered in the differential diagnosis of cytopenias and myelodsyplasia, particularly in the growing number of pediatric patients with TPN dependency or malabsorption.