Critical Role of Tripartite Fusion and LBD Truncation in Certain RARA- and all RARG-Related Atypical APL.

Atypical acute promyelocytic leukemia (aAPL) presents a complex landscape of retinoic acid receptor (RAR) fusion genes beyond the well-known PML::RARA fusion. Among these, 31 individually rare RARA and RARG fusion genes have been documented, often reported in the canonical X::RAR bipartite fusion form. Intriguingly, some artificially mimicked bipartite X::RAR fusions respond well to all-trans retinoic acid (ATRA) in vitro, contrasting with the ATRA resistance observed in patients. To unravel the underlying mechanisms, we conducted a comprehensive molecular investigation into the fusion transcripts in 27 RARA fusion gene-positive aAPL (RARA-aAPL) and 21 RARG-aAPL cases. Our analysis revealed an unexpected novel form of X::RAR::X or X::RAR::Y-type tripartite fusions in certain RARA- and all RARG-aAPL cases, with shared features and notable differences between these two disease subgroups. In RARA-aAPL cases, the occurrence of RARA 3' splices was associated with their 5' fusion partner genes, mapping across the coding region of helix 11_12 (H11_12) within the ligand-binding domain (LBD), resulting in LBD-H12 or H11_12 truncation. In RARG-aAPL cases, RARG 3' splices were consistently localized to the terminus of exon 9, leading to LBD-H11_12 truncation. Significant differences were also observed between RARA and RARG 5' splice patterns. Our analysis also revealed extensive involvement of transposable elements in constructing RARA and RARG 3' fusions, suggesting transposition mechanisms for fusion gene ontogeny. Both protein structural analysis and experimental results highlighted the pivotal role of LBD-H11_12/H12 truncation in driving ATRA unresponsiveness and leukemogenesis in tripartite fusion-positive aAPL, through a protein allosteric dysfunction mechanism.

The novel HLA-B*13:01:23 allele, identified by Sanger dideoxy nucleotide sequencing in a Chinese individual.

HLA-B*13:01:23 differs from HLA-B*13:01:01:01 by one nucleotide in exon 5.

Identification of a novel WAS mutation and the non-splicing effect of a second-site mutation in a Chinese pedigree with Wiskott-Aldrich syndrome.

BACKGROUND: Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency disorder caused by abnormal expression of the WAS protein (WASp) due to mutations in the WAS gene, and is generally characterized by microthrombocytopenia, eczema, recurrent infections, and high susceptibility to autoimmune complications and hematological malignancies. RESULTS: Herein, we identified a novel WAS mutation (c.158 T > C) using next-generation sequencing in a Chinese pedigree with WAS. The expression of WASp in the patients and their families was detected by flow cytometry and western blot analysis. To explore the exon-splicing effect of intron mutations and the correlation between the genotype and clinical phenotype, four groups of wild-type (WT), exon mutant, intron mutant, and combined mutant recombinant plasmids were transfected into COS-7 cells in vitro. The proband showed dramatically decreased WASp expression, while the female carriers showed a slightly lower level of WASp. The expression of products in the mutant and WT recombinant plasmids was detected by real-time fluorescence quantitative polymerase chain reaction (PCR), which showed a significant reduction in the combined mutant group than in the WT, exon mutant, and intron mutant groups. The length of the expression products in the four groups showed no differences, each containing 360 base pairs. Sequence analysis confirmed that the c.158 T > C mutation appeared in the exon mutant and combined mutant groups, whereas the intron variant c.273 + 14C > T caused no other sequence changes. CONCLUSION: This study confirmed that the intron mutation did not affect the splicing of exons and excluded the influence of the double mutations at the transcription level on the severe clinical manifestations in the cousin. This in vitro study provided new insights into the pathogenesis of intronic mutations in WAS.

Evidence of long-lasting anti-CD19 activity of engrafted CD19 chimeric antigen receptor-modified T cells in a phase I study targeting pediatrics with acute lymphoblastic leukemia.

Ninety percent of relapse/refractory B-cell acute lymphatic leukemia (R/R B-ALL) patients can achieve complete remission (CR) after CD19-targeting chimeric antigen receptor T (CAR-T) cell therapy. However, around 50% of them relapse in 1 year. Persistent CAR-T cell engraftment is considered as the key to remain durable remission. Here, we initiated a phase I study to treat 10 pediatric B-ALL patients using a CD19-targeted second generation CAR with a 4-1BB intracellular costimulatory domain. All patients received a standard fludarabine and cyclophosphamide (FC) preconditioning regiment, followed by a CAR-T infusion with a median number of 0.5 (0.3-1.58) × 106 CAR+ T cells/kg. The pretreatment tumor burdens were high with a median bone marrow (BM) blasts percentage of 59.2% (7.31%-86.2%), excluding one patient only with brain infiltration of leukemia cells (0% BM blasts). The initial CR rate was 80% (n = 8/10). Four patients (40%) experienced serious (grade > 2) cytokine release syndrome (CRS) and three patients (30%) with obvious neurotoxicity. Monthly assessments of CD19+ minimal residual disease (MRD) and CAR-T engraftment demonstrated the anti-CD19 activity of long-term engrafted CAR-T cell clones in one patient for more than 2 years.

Role of Beclin-1-Mediated Autophagy in the Survival of Pediatric Leukemia Cells.

BACKGROUND/AIMS: Acute and chronic leukemia are severe malignant cancers worldwide, and can occur in pediatric patients. Since bone marrow cell transplantation is seriously limited by the availability of the immune-paired donor sources, the therapy for pediatric leukemia (PL) remains challenging. Autophagy is essential for the regulation of cell survival in the harsh environment. However, the role of autophagy in the survival of PL cells under the oxidative stress, e.g. chemotherapy, remain ill-defined. In the current study, we addressed these questions. METHODS: We analyzed the effects of oxidative stress on the cell viability of PL cells in vitro, using a CCK-8 assay. We analyzed the effects of oxidative stress on the apoptosis and autophagy of PL cells. We analyzed the levels of Beclin-1 and microRNA-93 (miR-93) in PL cells. Prediction of binding between miR-93 and 3'-UTR of Beclin-1 mRNA was performed by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. The relationship between levels of miR-93 and patients' survival was analyzed in PL patients. RESULTS: We found that oxidative stress dose-dependently increased autophagy in PL cells. While low-level oxidative stress did not increase apoptosis, high-level oxidative stress increased apoptosis, seemingly from failure of autophagy-mediated cell survival. High-level oxidative stress appeared to suppress the protein levels of an autophagy protein Beclin-1 in PL cells, possibly through induction of miR-93, which inhibited the translation of Beclin-1 mRNA via 3'-UTR binding. CONCLUSION: Beclin-1-mediated autophagy plays a key role in the survival of PL cells against oxidative stress. Induction of miR-93 may increase the sensitivity of PL cells to oxidative stress during chemotherapy to improve therapeutic outcome.

Prognostic significance of FLT3-ITD in pediatric acute myeloid leukemia: a meta-analysis of cohort studies.

The purpose of the study was to assess the effect of the internal tandem duplication in FMS-like tyrosine kinase 3 (FLT3-ITD) on the outcome in pediatric acute myeloid leukemia (AML) patients. We identified eligible studies from several databases including PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) (from January 1995 to July 2015). Ten studies of 1661 pediatric patients with AML were included in exploring the relationship between the FLT3-ITD and overall survival (OS)/event free survival (EFS). Pediatric patients with AML with FLT3-ITD had worse OS [HR = 2.19 (1.60-3.01)]/EFS [HR = 1.70 (1.37-2.11)] than those patients without FLT3-ITD. Furthermore, FLT3-ITD had unfavorable effect on OS/EFS in the subgroups of NOS, uni/multivariate model, number of patients, the length of following-up, and patient source. The findings of this meta-analysis indicated that FLT3-ITD had negative impact on pediatric patients with AML.

Childhood renal tumor: a report from a Chinese Children's Cancer Group.

Here we investigated the establishment of multicenter cooperative treatment groups in China, as well as radiotherapy compliance and effectiveness among children with renal tumors. Medical records were reviewed for 316 children with renal tumors diagnosed by a multicenter cooperative group from 14 hospitals in China from 1998 to 2012. Median patient age was 29.5 months (range, 2-173 months old), and male-to-female ratio was 1.4 : 1. After a median follow-up of 22 months (range, 1-177 months), five-year event-free survival rates were 72% overall; 76.1% for favorable histology (251 cases); 59% for unfavorable histology (27 cases); and 91%, 75%, 71%, 53%, and 48.5%, respectively for Stages I, II, III, IV, and V. Following standardized criteria, radiation therapy was indicated for 153 patients, among whom five-year event-free survival was 72.8% for the 95 who received radiation and 24% for the 58 patients who did not. Our results are reasonable but can be further improved and show the feasibility of a multicenter cooperative group model for childhood renal tumor treatment in China. Radiation therapy is important for stage III and IV patients but remains difficult to implement in some parts of China. Government management departments and medical professionals must pay attention to this situation. This clinical trial is registered with ChiCTR-PRCH-14004372.

[Expression of CREB/Bcl-2 in bone marrow mononuclear cells of children with acute leukemia].

OBJECTIVE: To study the expression and role of cyclic-AMP response binding protein (CREB) and Bcl-2 in children with acute leukemia. METHODS: Ninety-two children with acute leukemia (leukemia group) and 30 children with non-hematologic malignancies (control group) were enrolled. The mRNA and protein expression of CREB and Bcl-2 in bone marrow mononuclear cells were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot. RESULTS: The mRNA and protein expression of CREB and Bcl-2 in the leukemia group was significantly higher than that in the control group (p<0.01). There were no significant differences in the expression of CREB and Bcl-2 between acute lymphoblastic leukemia and acute myeloid leukemia subgroups. At the initial diagnosis, the mRNA and protein expression of CREB and Bcl-2 in children with extramedullary infiltration was higher than that in children without (p<0.05). In the leukemia group, the mRNA and protein expression of CREB and Bcl-2 in the complete remission subgroup was significantly lower than that in the non-complete remission subgroup (p<0.01). High mRNA expression of CREB and Bcl-2 in the leukemia group was positively correlated with peripheral blood leucocyte counts (r=0.62, 0.71 respectively, p<0.05). There was a positive correlation between mRNA and protein expression of CREB and Bcl-2 (r=0.75, 0.68 respectively; p<0.05). CONCLUSIONS: The expression of CREB and Bcl-2 may be correlated with the pathogenesis and clinical prognosis of childhood leukemia, however, their expression may not be associated with the classification of acute leukemia.