Tracey O'Brien

Adolescent and young adult cancer: a revolution in evolution?

The optimal management of adolescent and young adult cancer has been the subject of vigorous debate in paediatric and adult cancer community for many years. This debate is rapidly coming to the boil. There is international recognition that not only is cancer in young people on the rise but also that improvements in outcomes of cancer in young people lag well behind the advances that have been achieved for both children and older adults in the past 30 years. The underlying problems appear to relate to a complex set of interactions between the health‐care system and the prevalence of cancer in this age group and the unique psychosocial and educational needs of this population. This article explores why we should be concerned about Australian health outcomes in this group and considers how best we might respond to these concerns.

Antifungal Therapy in Children With Invasive Fungal Infections: A Systematic Review

Invasive fungal infections are associated with significant morbidity and mortality. Differences between children and adults are reported, yet few trials of antifungal agents have been performed in pediatric populations. We performed a systematic review of the literature to guide appropriate pediatric treatment recommendations. From available trials that compared antifungal agents in either prolonged febrile neutropenia or invasive candidal or Aspergillus infection, no clear difference in treatment efficacy was demonstrated, although few trials were adequately powered. Differing antifungal pharmacokinetics between children and adults were demonstrated, requiring dose modification. Significant differences in toxicity, particularly nephrotoxicity, were identified between classes of antifungal agents. Therapy needs to be guided by the pathogen or suspected pathogens, the degree of immunosuppression, comorbidities (particularly renal dysfunction), concurrent nephrotoxins, and the expected length of therapy.

Autoimmune haemolytic anaemia complicating haematopoietic cell transplantation in paediatric patients: high incidence and significant mortality in unrelated donor transplants for non-malignant diseases

Haemolytic anaemia is a recognized complication of haematopoietic cell transplantation (HCT) and can result from alloimmune‐ or autoimmune‐derived antibodies. Unlike alloimmune haemolytic anaemia, autoimmune haemolytic anaemia (AIHA) is poorly understood, particularly in the paediatric population where only case reports have been published. Between January 1995 and July 2001, 439 consecutive allogeneic HCT were performed in paediatric patients at the University of Minnesota, 31% (n = 136) from related donors (RD) and 69% (n = 303) from unrelated donors (URD). Nineteen cases of AIHA were identified with documented significant haemolysis and a positive direct antiglobulin test. All cases of AIHA occurred in URD transplants, yielding a cumulative incidence of AIHA post‐transplant of 6% at 1 year. Patients transplanted for non‐malignant disease, particularly metabolic diseases, had a higher incidence of AIHA post‐HCT when compared with patients transplanted for malignancies (RR 4·2 95% CI 1·2–15·4, P = 0·01). Mortality was high in our series of 19 patients with 10 (53%) dying following the onset of AIHA, three as a direct consequence of haemolysis. Fifty per cent of deaths occurred from infection while on immunosuppressive therapy to treat haemolysis. Alternative treatment strategies were employed, with the majority of patients demonstrating disease refractory to traditional steroid therapy.

Genome-wide analysis of transcriptional regulators in human HSPCs reveals a densely interconnected network of coding and noncoding genes

Genome-wide combinatorial binding patterns for key transcription factors (TFs) have not been reported for primary human hematopoietic stem and progenitor cells (HSPCs), and have constrained analysis of the global architecture of molecular circuits controlling these cells. Here we provide high-resolution genome-wide binding maps for a heptad of key TFs (FLI1, ERG, GATA2, RUNX1, SCL, LYL1, and LMO2) in human CD34(+) HSPCs, together with quantitative RNA and microRNA expression profiles. We catalog binding of TFs at coding genes and microRNA promoters, and report that combinatorial binding of all 7 TFs is favored and associated with differential expression of genes and microRNA in HSPCs. We also uncover a previously unrecognized association between FLI1 and RUNX1 pairing in HSPCs, we establish a correlation between the density of histone modifications that mark active enhancers and the number of overlapping TFs at a peak, we demonstrate bivalent histone marks at promoters of heptad target genes in CD34(+) cells that are poised for later expression, and we identify complex relationships between specific microRNAs and coding genes regulated by the heptad. Taken together, these data reveal the power of integrating multifactor sequencing of chromatin immunoprecipitates with coding and noncoding gene expression to identify regulatory circuits controlling cell identity.

Glycogen Synthase Kinase-3β Inhibition Preserves Hematopoietic Stem Cell Activity and Inhibits Leukemic Cell Growth

Ex vivo expansion of cord blood cells generally results in reduced stem cell activity in vivo. Glycogen synthase kinase‐3β (GSK‐3β) regulates the degradation of β‐catenin, a critical regulator of hematopoietic stem cells (HSCs). Here we show that GSK‐3β inhibition activates β‐catenin in cord blood CD34+ cells and upregulates β‐catenin transcriptional targets c‐myc and HoxB4, both known to regulate HSC self‐renewal. GSK‐3β inhibition resulted in delayed ex vivo expansion of CD34+ cells, yet enhanced the preservation of stem cell activity as tested in long‐term culture with bone marrow stroma. Delayed cell cycling, reduced apoptosis, and increased adherence of hematopoietic progenitor cells to bone marrow stroma were observed in these long‐term cultures treated with GSK‐3β inhibitor. This improved adherence to stroma was mediated via upregulation of CXCR4. In addition, GSK‐3β inhibition preserved severe combined immunodeficiency (SCID) repopulating cells as tested in the nonobese diabetic/SCID mouse model. Our data suggest the involvement of GSK‐3β inhibition in the preservation of HSC and their interaction with the bone marrow environment. Methods for the inhibition of GSK‐3β may be developed for clinical ex vivo expansion of HSC for transplantation. In addition, GSK‐3β inhibition suppressed leukemic cell growth via the induction of apoptosis mediated by the downregulation of survivin. Modulators of GSK‐3β may increase the range of novel drugs that specifically kill leukemic cells while sparing normal stem cells.

GSK‐3β Inhibition Promotes Engraftment of Ex Vivo‐Expanded Hematopoietic Stem Cells and Modulates Gene Expression

Glycogen synthase kinase‐3β (GSK‐3β) has been identified as an important regulator of stem cell function acting through activation of the wingless (Wnt) pathway. Here, we report that treatment with an inhibitor of GSK‐3β, 6‐bromoindirubin 3′‐oxime (BIO) delayed cell cycle progression by increasing cell cycle time. BIO treatment resulted in the accumulation of late dividing cells enriched with primitive progenitor cells retaining the ability for sustained proliferation. In vivo analysis using a Non‐obese diabetic/severe combined immunodeficient (NOD/SCID) transplantation model has demonstrated that pretreatment with BIO promotes engraftment of ex vivo‐expanded hematopoietic stem cells. BIO enhanced the engraftment of myeloid, lymphoid and primitive stem cell compartments. Limiting dilution analysis of SCID repopulating cells (SRC) revealed that BIO treatment increased human chimerism without increasing SRC frequency. Clonogenic analysis of human cells derived from the bone marrow of transplant recipient mice demonstrated that a higher level of human chimerism and cellularity was related to increased regeneration per SRC unit. Gene expression analysis showed that treatment with BIO did not modulate the expression of canonical Wnt target genes upregulated during cytokine‐induced cell proliferation. BIO increased the expression of several genes regulating Notch and Tie2 signaling downregulated during ex vivo expansion, suggesting a role in improving stem cell engraftment. In addition, treatment with BIO upregulated CDK inhibitor p57 and downregulated cyclin D1, providing a possible mechanism for the delay seen in cell cycle progression. We conclude that transient, pharmacologic inhibition of GSK‐3β provides a novel approach to improve engraftment of expanded HSC after stem cell transplantation. STEM CELLS 2011;29:108–118

Transplant-Related Mortality Following Allogeneic Hematopoeitic Stem Cell Transplantation for Pediatric Acute Lymphoblastic Leukemia: 25-Year Retrospective Review

Over the last 25 years, donor source, conditioning, graft‐versus‐host disease prevention and supportive care for children undergoing hematopoeitic stem cell transplantation (HSCT) have changed dramatically. HSCT indications for acute lymphoblastic leukemia (ALL) now include high‐risk patients in first and subsequent remission. There is a large burden of infectious and pre‐HSCT morbidities, due to myelosuppressive therapy required for remission induction. We hypothesized that, despite these trends, overall survival (OS) had increased.

Using Small Molecule GSK3β Inhibitors to Treat Inflammation

Glycogen Synthase Kinase 3 beta (GSK3β) is a serine-threonine kinase originally identified for its role in the conversion of glucose to glycogen. Pharmacological inhibition can be achieved by drug binding to ATP or magnesium binding sites on the enzyme. Pharmaceutical companies have developed several small molecule GSK3β inhibitors for diabetes research. Additionally, GSK3β inhibitors are being clinically tested as therapeutics for neurological diseases, however, the mechanisms of involvement are unclear. Several studies have shown that the therapeutic effect of GSK3β inhibition is associated with the inhibition of inflammation. Similarly, the mechanisms underlying the anti-inflammatory function of GSK3β inhibition are not well understood. GSK3β inhibition attenuates activation of the pro-inflammatory transcription factor NFκB, and activates the immuno-modulatory transcription factor β-catenin. GSK3β inhibition has also been shown to induce secretion of the anti-inflammatory cytokine IL-10. In addition, pharmacological inhibition of GSK3β suppressed alloreactive T-cell responses. The combined anti-proliferative and anti-inflammatory properties of small molecule inhibitors of GSK3β make them an attractive treatment modality towards the control of inflammation.

Glycogen synthase kinase−3β inhibitors suppress leukemia cell growth

OBJECTIVE The objective of this study was to investigate the effect of small molecule inhibitors of glycogen synthase kinase-3β (GSK-3β) on leukemia cell growth and survival. MATERIALS AND METHODS Analysis of cytotoxicity and cell proliferation was conducted using the MTS assay, cell-cycle analysis, and division tracking. Apoptosis was investigated by Annexin-V/7-aminoactinomycin D and caspase-3 expression. The effect of GSK-3β inhibitors was also tested in vivo in an animal model of leukemia. Gene expression analysis was performed to identify the genes modulated by GSK-3β inhibition in leukemia cells. RESULTS GSK-3β inhibitors suppress cell growth and induce apoptosis in seven leukemia cell lines of diverse origin, four acute myeloid leukemia, one myelodysplastic syndrome, and one acute lymphoblastic leukemia samples. GSK-3β inhibitors are cytotoxic for rapidly dividing clonogenic leukemia blasts, and higher doses of the inhibitors are needed to eliminate primitive leukemia progenitor/stem cells. Slow cell-division rate, low drug uptake, and interaction with bone marrow stroma make leukemia cells more resistant to apoptosis induced by GSK-3β inhibitors. Global gene expression analysis combined with functional approaches identified multiple genes and specific signaling pathways modulated by GSK-3β inhibition. An important role for Bcl2 in the regulation of apoptosis induced by GSK-3β inhibitors was defined by expression analysis and confirmed by using pharmacological inhibitors of the protein. In vivo administration of GSK-3β inhibitors delayed tumor formation in a mouse leukemia model. GSK-3β inhibitors did not affect hematopoietic recovery following irradiation. CONCLUSIONS Our data support further evaluation of GSK-3β inhibitors as promising novel agents for therapeutic intervention in leukemia and warrant clinical investigation in leukemia patients.

The Role of Glycogen Synthase Kinase-3β in Normal Haematopoiesis, Angiogenesis and Leukaemia

Glycogen synthase kinase 3 beta (GSK-3beta) was one of the first kinases identified and studied, initially for its role in the regulation of glycogen synthesis. Over the past decade, interest in GSK-3beta has grown far beyond glycogen metabolism, and this is due in large measure to the critical role that GSK-3beta plays in the regulation of many other cellular processes, particularly cell proliferation and apoptosis. GSK-3beta has been shown to regulate the proteolysis and sub-cellular compartmentalization of a number of proteins directly involved in the regulation of cell cycling, proliferation, differentiation and apoptosis. GSK-3beta also regulates the degradation of proteins that regulate gene expression and thus affects a variety of important cell functions. Specifically, GSK-3beta controls the degradation of beta-catenin, the main effector of Wnt that regulates haematopoiesis and stem cell function. In this case GSK-3beta is a negative regulator of Wnt. In contrast, GSK-3beta positively regulates NF-kappaB, another important biochemical pathway also involved in the regulation of multiple aspects of normal and aberrant haematopoiesis. GSK-3beta regulates degradation of IkappaB, a central inhibitor of NF-kappaB. In this way, GSK-3beta acts to control the resistance of leukaemic cells to chemotherapy through the modulation of NF-kappaB, a critical factor in maintaining leukaemic cell growth. In addition, GSK-3beta regulates the pro-inflammatory activity of NF-kappaB. As GSK-3beta is a pleiotropic regulator, inhibitors may increase the range of novel anti-leukaemic and anti-inflammatory drugs that control immune response.