Juvenile Myelomonocytic Leukemia and other myelodysplastic/myeloproliferative neoplasms

Juvenile Myelomonocytic Leukemia (JMML) is a clonal hematopoietic disorder that usually occurs in early childhood, characterized by hyperactivation of the RAS signaling pathway. About 90% of patients have mutations in 1 of 5 genes (PTPN11, NRAS, KRAS, NF1, CBL) that define genetically and clinically distinct subtypes of the disease, with a highly variable clinical course. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the therapy of choice for most patients with JMML, although children with CBL mutations and few of those with N-RAS mutations may have spontaneous resolution of hematologic abnormalities. The results of HSCT in patients with JMML have progressively improved over time, but relapse is still an important cause of treatment failure.

Adult Acute Myeloid Leukemia with the KMT2A-Mixed Lineage Leukemia T10 Fusion: An Analysis of 10 Cases Showed Common Features and Frequent Mutations in the RAS Signaling Pathway

Mixed lineage leukemia (<i>MLL) T10</i> is a relatively rare partner for the <i>KMT2A</i> lysine (K)-specific methyltransferase 2A gene. The common features and coexisting mutations of acute myeloid leukemia (AML) patients with <i>KMT2A-MLLT10</i> remain unknown. In this study, 10 adult AML patients with <i>KMT2A-MLLT10</i> fusions were picked up from 496 AML patients by using RT-polymerase chain reaction (PCR) and/or fluorescence in situ hybridization, and then screened for mutations in the 49 genes panel with next-generation sequencing and PCR, followed by direct Sanger sequencing. Of the 10 unique individuals identified, 6 were male and 4 were female (M:F ratio, 1.5:1) with ages ranging from 19 to 52 years (median 39.5 years). Most (90%, 9/10) patients with <i>KMT2A-MLLT10</i> were accompanied by additional mutations. Twelve mutated genes were detected, averaging 2.1 mutations per patient (range, 0–4). The most frequently mutated gene was <i>NRAS</i> (<i>n</i> = 5). Clinical and laboratory data pointed to common features: French American British-M5 subtype (<i>n</i> = 7), a high rate of relapse, and biomarkers CD33 (<i>n</i> = 10), CD117 (<i>n</i> = 9), CD13 (<i>n</i> = 8), and CD64 (<i>n</i> = 8). Overall, most patients harbored at least one mutation. A high incidence of mutations affecting the RAS signaling pathway or RAS regulating components was found in 50% (5/10) patients. The overall survival is about 12.0 months. Allogeneic-hematopoietic stem cell transplantation trends to improve survival in selected patients.

Network Pharmacology Study on Morus alba L. Leaves: Pivotal Functions of Bioactives on RAS Signaling Pathway and Its Associated Target Proteins against Gout

M. alba L. is a valuable nutraceutical plant rich in potential bioactive compounds with promising anti-gouty arthritis. Here, we have explored bioactives, signaling pathways, and key proteins underlying the anti-gout activity of M. alba L. leaves for the first-time utilizing network pharmacology. Bioactives in M. alba L. leaves were detected through GC-MS (Gas Chromatography-Mass Spectrum) analysis and filtered by Lipinski’s rule. Target proteins connected to the filtered compounds and gout were selected from public databases. The overlapping target proteins between bioactives-interacted target proteins and gout-targeted proteins were identified using a Venn diagram. Bioactives-Proteins interactive networking for gout was analyzed to identify potential ligand-target and visualized the rich factor on the R package via the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway on STRING. Finally, a molecular docking test (MDT) between bioactives and target proteins was analyzed via AutoDock Vina. Gene Set Enrichment Analysis (GSEA) demonstrated that mechanisms of M. alba L. leaves against gout were connected to 17 signaling pathways on 26 compounds. AKT1 (AKT Serine/Threonine Kinase 1), γ-Tocopherol, and RAS signaling pathway were selected as a hub target, a key bioactive, and a hub signaling pathway, respectively. Furthermore, three main compounds (γ-Tocopherol, 4-Dehydroxy-N-(4,5-methylenedioxy-2-nitrobenzylidene) tyramine, and Lanosterol acetate) and three key target proteins—AKT1, PRKCA, and PLA2G2A associated with the RAS signaling pathway were noted for their highest affinity on MDT. The identified three key bioactives in M. alba L. leaves might contribute to recovering gouty condition by inactivating the RAS signaling pathway.

Post-transcriptional gene regulation by the RNA binding protein IGF2BP3 is critical for MLL-AF4 mediated leukemogenesis

ABSTRACTDespite recent advances in therapeutic approaches, patients with MLL-rearranged leukemia still have poor outcomes and a high risk of relapse. Here, we found that MLL-AF4, the most common MLL fusion protein in patients, transcriptionally induces IGF2BP3 and that IGF2BP3 strongly amplifies MLL-Af4 mediated leukemogenesis. Deletion of Igf2bp3 significantly increases the survival of mice with MLL-Af4 driven leukemia and greatly attenuates disease. At the cellular level, MLL-Af4 leukemia-initiating cells require Igf2bp3 for their function in leukemogenesis. eCLIP and transcriptome analysis of MLL-Af4 transformed stem and progenitor cells and MLL-Af4 bulk leukemia cells reveals a complex IGF2BP3-regulated post-transcriptional operon governing leukemia cell survival and proliferation. Critical mRNA targets include important leukemogenic genes such as in the Hoxa locus and numerous genes within the Ras signaling pathway. Together, our findings show that IGF2BP3 is an essential positive regulator of MLL-AF4 mediated leukemogenesis and is a potential therapeutic target in this disease.

THER-07. INHIBITION OF THE RAS SIGNALING ENHANCES VIRAL ONCOLYSIS IN MALIGNANT GLIOMAS

Pediatric malignant glioma indicates rapid proliferation, widely infiltrative properties and resistance to various therapies, and carries a very poor prognosis. There are methods of using virus within novel therapies under development against malignant neoplasms, which have been studied for many years already. We examined the treatment with sunitinib or GW5074 to our experimental model of vaccinia virus therapy for malignant glioma, and then evaluated changes in the tumoricidal activity, the viral infectivity, and the impact on the Ras signaling pathway. Glioma cells (U251MG, LN229, LN18, rat C6) infected with vaccinia virus was fatal, in its course of death, apoptosis and autophagy were induced. The activity of Ras signaling in vaccinia-infected cells heightened in the early stage and declined in the late stage Inhibition of the Ras signaling pathway at the early stage of viral infection prevented vaccinia virus replication, while viral oncolysis was not inhibited when the pathway was blocked after sufficient viral spread. Glioma cells infected with vaccinia virus are led to cell death. Vaccinia virus regulates Ras or other survival signaling pathways in the infected cells. It enhances the signaling in the early stage (viral replicative period), however suppresses in the later stage (virus-releasing stage). Inhibition of the Ras signaling pathway at the early stage of viral infection prevents vaccinia virus from replicating, while viral oncolysis appears to be accelerated when the pathway was blocked after sufficient viral reproduction.