Shiann-Tarng Jou

Essential, Nonredundant Role for the Phosphoinositide 3-Kinase p110δ in Signaling by the B-Cell Receptor Complex

ABSTRACT Many receptor and nonreceptor tyrosine kinases activate phosphoinositide 3-kinases (PI3Ks). To assess the role of the δ isoform of the p110 catalytic subunit of PI3Ks, we derived enzyme-deficient mice. The mice are viable but have decreased numbers of mature B cells, a block in pro-B-cell differentiation, and a B1 B-cell deficiency. Both immunoglobulin M receptor-induced Ca2+ flux and proliferation in response to B-cell mitogens are attenuated. Immunoglobulin levels are decreased substantially. The ability to respond to T-cell-independent antigens is markedly reduced, and the ability to respond to T-cell-dependent antigens is completely eliminated. Germinal center formation in the spleen in response to antigen stimulation is disrupted. These results define a nonredundant signaling pathway(s) utilizing the δ isoform of p110 PI3K for the development and function of B cells.

Long-term results of Taiwan Pediatric Oncology Group studies 1997 and 2002 for childhood acute lymphoblastic leukemia

The long-term outcome of 1390 children with acute lymphoblastic leukemia (ALL), treated in two successive clinical trials (Taiwan Pediatric Oncology Group (TPOG)-ALL-97 and TPOG-ALL-2002) between 1997 and 2007, is reported. The event-free survival improved significantly (P=0.0004) over this period, 69.3±1.9% in 1997–2001 to 77.4±1.7% in 2002–2007. A randomized trial in TPOG-97 testing L-asparaginase versus epidoxorubicin in combination with vincristine and prednisolone for remission induction in standard-risk (SR; low-risk) patients yielded similar outcomes. Another randomized trial, in TPOG-2002, showed that for SR patients, two reinduction courses did not improve long-term outcome over one course. Decreasing use of prophylactic cranial irradiation in the period 1997–2008 was not associated with increased rates of CNS relapse, prompting complete omission of prophylactic cranial irradiation from TPOG protocols, beginning in 2009. Decreased use of etoposide and cranial irradiation likely contributed to the low incidence of second cancers. High-risk B-lineage ALL, T-cell, CD10 negativity, t(9;22), infant, and higher leukocyte count were consistently adverse factors, whereas hyperdiploidy >50 was a consistently favorable factor. Higher leukocyte count and t(9;22) retained prognostic significance in both TPOG-97 and TPOG-2002 by multivariate analysis. Although long-term outcome in TPOG clinical trials is comparable with results being reported worldwide, the persistent strength of certain prognostic variables and the lower frequencies of favorable outcome predictors, such as ETV6-RUNX1 and hyperdiploidy >50, in Taiwanese children warrant renewed effort to cure a higher proportion of patients while preserving their quality of life.

Phospholipase Cγ2 Is Essential for Specific Functions of FcεR and FcγR

Phospholipase Cγ2 (PLCγ2) plays a critical role in the functions of the B cell receptor in B cells and of the FcRγ chain-containing collagen receptor in platelets. Here we report that PLCγ2 is also expressed in mast cells and monocytes/macrophages and is activated by cross-linking of FcεR and FcγR. Although PLCγ2-deficient mice have normal development and numbers of mast cells and monocytes/macrophages, we demonstrate that PLCγ2 is essential for specific functions of FcεR and FcγR. While PLCγ2-deficient mast cells have normal mitogen-activated protein kinase activation and cytokine production at mRNA levels, the mutant cells have impaired FcεR-mediated Ca2+ flux and inositol 1,4,5-trisphosphate production, degranulation, and cytokine secretion. As a physiological consequence of the effect of PLCγ2 deficiency, the mutant mice are resistant to IgE-mediated cutaneous inflammatory skin reaction. Macrophages from PLCγ2-deficient mice have no detectable FcγR-mediated Ca2+ flux; however, the mutant cells have normal FcγR-mediated phagocytosis. Moreover, PLCγ2 plays a nonredundant role in FcγR-mediated inflammatory skin reaction.

Severe Bacterial Infection in Transfusion-Dependent Patients with Thalassemia Major

The incidence and clinical spectrum of severe bacterial infection were studied in 89 patients with thalassemia major that was diagnosed between January 1971 and March 2002. There were 20 patients with 24 episodes of severe bacterial infection, resulting in an incidence of 1.6 infections per 100 patient-years. The clinical spectrum included liver abscess (6 cases), septicemia (6 cases), soft-tissue infection (2 cases), osteomyelitis (2 cases), corneal ulcer (1 case), enteritis (1 case), and abscesses of the lung, kidney, intra-abdominal region, retropharynx, gums, and buttocks (1 case each). The leading causal microorganisms were gram-negative bacilli, especially Klebsiella pneumoniae (10 of 20 isolates). Other responsible pathogens were Pseudomonas aeruginosa (2/20), Vibrio vulnificus (2/20), Acinetobacter baumanii (1/20), Streptococcus intermidius (1/20), Yersinia enterocolitica (1/20), Staphylococcus aureus (1/20), Escherichia coli (1/20), and Salmonella species (1/20). Splenectomy and delays in the start of iron-chelating therapy were 2 independent risk factors.

IKZF1 deletions predict a poor prognosis in children with B‐cell progenitor acute lymphoblastic leukemia: A multicenter analysis in Taiwan

Despite current risk‐directed therapy, approximately 15–20% of pediatric patients with acute lymphoblastic leukemia (ALL) have relapses. Recent genome‐wide analyses have identified that an alteration of IKZF1 is associated with very poor outcomes in B‐cell progenitor ALL. In this study, we determined the prognostic significance of IKZF1 deletions in patients with childhood ALL. This study analyzed 242 pediatric B‐cell progenitor ALL patients in Taiwan. We developed a simple yet sensitive multiplex quantitative PCR coupled with capillary electrophoresis to accurately determine the allele dose of IKZF1, and high resolution melting was used for mutation screening for all coding exons of IKZF1. Twenty‐six (10.7%) pediatric B‐cell progenitor ALL patients were found to harbor these deletions. Most of the deletions were broader deletions that encompassed exon 3 to exon 6, consistent with previous reports. Genomic sequencing of IKZF1 was carried out in all cases and no point mutations were identified. Patients with IKZF1 deletions had inferior event‐free survival (P < 0.001), and overall survival (P = 0.0016). The association between IKZF1 deletions and event‐free survival was independent of age, leukocyte count at presentation, and cytogenetic subtype by multivariate Cox analysis (P = 0.003, hazard ratio = 2.45). This study indicates that detection of IKZF1 deletions upon diagnosis of B‐cell progenitor ALL may help to identify patients at risk of treatment failure. IKZF1 deletions could be incorporated as a new high‐risk prognostic factor in future treatment protocols. To the best of our knowledge, this is the first study to examine the poor prognosis of IKZF1 deletions in an Asian population. (Cancer Sci 2011; 102: 1874–1881)

Recombinant Urate Oxidase (Rasburicase) for the Prevention and Treatment of Tumor Lysis Syndrome in Patients with Hematologic Malignancies

In this multicenter, nonrandomized, open-label clinical trial conducted from July 2003 to July 2004, recombinant urate oxidase (rasburicase) was administered to patients at risk for tumor lysis syndrome before or during the initiation of chemotherapy. Forty-five patients were enrolled, including 18 children (10 with acute lymphoblastic leukemia, 6 with high-grade lymphoma, and 2 with acute myeloid leukemia) and 27 adults (8 with acute lymphoblastic leukemia, 4 with high-grade lymphoma, 9 with multiple myeloma, and 6 with acute myeloid leukemia). The age ranged from 3 to 98 years, with a median age of 7 years in children and 59.3 years in adults. There were 14 males and 4 females in the pediatric group and 18 males and 9 females in the adult group. Rasburicase 0.2 mg/kg was administered intravenously once a day for 2–6 days, for a median of 3 days in children and of 4 days in adults. After 3 days of treatment, the median uric acid levels in the 18 children decreased from 10.5 mg/dl (range 8–18.6) to 0.5 mg/dl (range 0.0–1.7). Similarly, in the 27 adults, the median levels decreased from 10.8 mg/dl (range 8–24.4) to 0.5 mg/dl (range 0.0–1.6). No significant changes were observed in serum potassium, calcium, and phosphorus concentrations. None of the patients required dialysis for acute renal failure. Rasburicase was very well tolerated, with only 1 adult having grade 1 vomiting. We conclude that rasburicase is safe and highly effective for preventing the complications of tumor lysis syndrome in patients with hematologic malignancies.

Leukemia Inhibitory Factor Regulates Trophoblast Giant Cell Differentiation via Janus Kinase 1-Signal Transducer and Activator of Transcription 3-Suppressor of Cytokine Signaling 3 Pathway

Suppressor of cytokine signaling 3 (SOCS3) inhibits leukemia-inhibitory factor (LIF) signaling and acts as a negative regulator. Deletion of SOCS3 causes embryonic lethality because of placental failure, and genetic reduction of LIF or the LIF receptor (LIFR) in SOCS3-deficient mice rescues placental defects and embryonic lethality; this indicates that SOCS3 is an essential inhibitor of LIFR signaling. However, the downstream signaling molecule that acts as a link between the LIFR and SOCS3 has not been identified. In this study we explored the downstream signaling of LIFR. The administration of LIF to SOCS3-heterozygous pregnant mice promotes trophoblast giant cell differentiation and accelerates placental failure in SOCS3-deficient mice. SOCS3-deficient trophoblast stem cells show enhanced and prolonged signal transducer and activator of transcription 3 (Stat3) activation by LIF stimulation. Further, in the trophoblasts of SOCS3-deficient placenta and differentiating cells from the choriocarcinoma-derived cell line Rcho-1 cells, constitutive activation of Stat3 is observed. The forced expression of SOCS3, dominant-negative Stat3, and dominant-negative Janus kinase 1 (JAK1) in Rcho-1 cells significantly suppressed the trophoblast giant cell differentiation of these cells. In addition, the number of trophoblast giant cells is significantly reduced concomitant with an increased number of precursor trophoblasts in JAK1-deficient placentas. Finally, JAK1 deficiency rescues placental defects and embryonic lethality in SOCS3-deficient mice. These results indicate that the LIFR signaling is finely coordinated by JAK1, Stat3, and SOCS3 and regulates trophoblast giant cell differentiation. In addition, these data establish that LIFR-JAK1-Stat3-SOCS3 signaling is an essential pathway for the regulation of trophoblast giant cell differentiation.

Identification of variations in the human phosphoinositide 3‐kinase p110δ gene in children with primary B‐cell immunodeficiency of unknown aetiology

Our recent study demonstrated that defects in p110δ result in B‐cell immunodeficiency that is very similar to that observed in BTK‐deficient mice. We revealed that the p110δ fit the B‐cell signal transduction complex and played a non‐redundant role in the development and function of B cells. In humans, most children with primary B‐cell immunodeficiency have mutations in the BTK, whereas a few have defects in the components of the B‐cell signal transduction complex. But little is known about the genetic variation of p110δ in children with defects in B‐cell immunodeficiency of unknown aetiology. Sixteen patients from 15 unrelated families and 112 normal controls underwent sequence analysis to identify genetic variations of the p110δ. Allele frequency in each group was also analysed and compared. We identified five single base‐pair polymorphic nucleotide exchanges in both patient and control groups with similar allele frequencies, which did not contribute to the immunodeficiency. Three of them are novel (m.953A>G, m.1200C>T and m.1561A>G), and the m.953A>G and m.1561A>G nucleotide exchanges are non‐synonymous (N253S and T456A, respectively). The novel m.1561A>G was in complete linkage disequilibrium with the known m.873A>G in our study of Taiwanese group. In addition, one novel single base‐pair missense mutation, m.3256G>A (E1021K), was identified in one boy with typical clinical features of primary B‐cell immunodeficiency and could not be found in either his family or the normal control population. By atomic structural analysis of the amino acid as well as the alignment comparison between species, it resulted in the replacement of the negative‐charged amino acid E with the positive‐charged amino acid K at codon 1021, located in the highly conservative and important catalytic functional domain. Our findings could shed light on further understanding the polymorphisms of p110δ in B‐cell immunodeficiency and different populations. Moreover, the 3256G>A missense mutation raised the attention and warranted further extensive analysis to elucidate the role of p110δ in human immunodeficiency.

Longitudinal observation and outcome of nonfamilial childhood haemophagocytic syndrome receiving etoposide-containing regimens

The long‐term outcome of 22 children treated with etoposide‐containing regimens for haemophagocytic syndrome (HS) were longitudinally studied; none of them had a family history of the disease. All patients received etoposide‐containing (150 mg/m2/d) regimens, combined, in 16 cases, with intravenous immunoglobulin (IVIG) and prednisolone. Complete remission (CR) was achieved in 12 patients, partial remission in seven, and early mortality occurred in three. Of the 12 CR patients, only four remain alive and disease‐free, with a median follow‐up of 47.4 months; one CR patient died due to infection and the remaining seven had relapsed diseases. Three patients with a partial response or with relapsed disease progressed to T‐cell lymphoma, characterized, in the two cases tested, by clonal chromosomal abnormalities. Epstein‐Barr virus (EBV) infection was implicated in disease pathogenesis in 15/22 patients. The overall survival was 45.5%, 40.9% and 40.9% at 1, 3 and 5 years, respectively, and disease‐free survival for CR patients at these same times was 45.5%, 36.4% and 36.4%. The etoposide‐containing regimen would appear to be an effective initial therapeutic option for childhood HS. However, in view of the frequency of partial remissions and relapsed disease, a more intensive chemotherapy or bone marrow transplantation should be applied. The progression to EBV‐containing T‐cell lymphoma in three patients is consistent with the previous observation that EBV‐associated HS is a potentially malignant disease.

Survival, mortality, and complications in patients with β‐Thalassemia major in northern Taiwan

Advances in treatment have improved the prognosis in β‐thalassemia major. We present the survival and complications pattern of those patients in northern Taiwan born after 1970.