Geffers, Robert

Abstract The uptake or expression of hepatitis B virus (HBV) proteins by dendritic cells (DCs) is considered important for disease outcome. Differential expression of microRNA (miRNA) may have a role in viral persistence and hepatocellular injury. The miRNA expression was investigated by microarray in DCs from different stages of HBV infection and liver disease namely, immune active (IA; n = 20); low replicative (LR; n = 20); HBeAg negative ( n = 20); acute viral hepatitis (AVH, n = 20) and healthy controls ( n = 20). miRNA levels were analyzed by unsupervised hierarchical clustering and principal component analyses and validated by quantitative polymerase Chain Reaction (qPCR). The miRNA‐messenger RNA (mRNA)regulatory networks identified 19 miRNAs and 12 target gene interactions in major histocompatibility complex and other immune pathways. miR‐2278, miR‐615‐3p, and miR‐3681‐3p were downregulated in the IA group compared to healthy control, miR‐152‐3p and miR‐3613‐3p in the LR group compared to IA group and miR‐152‐3p and miR‐503‐3p in HBe negative compared to LR group. However, miR‐7‐1‐1‐3p, miR‐192‐5p, miR‐195‐5p, and miR‐32‐5p in LR, miR‐342‐3p, and miR‐940 in HBe negative, and miR‐34a‐5p, miR‐130b‐3p, miR‐221‐3p, miR‐320a, miR‐324‐5p, and miR‐484 in AVH were upregulated. Further, qPCR confirmed changes in miRNA levels and their target genes associated with antigen processing and presentation. Thus, a deregulated network of miRNAs‐mRNAs in DCs seems responsible for an impaired immune response during HBV pathogenesis.

Abstract Abstract 1567 Fusions of the tyrosine kinase domain of JAK2 with multiple partners occur in leukemia/lymphoma where they are believed to promote JAK2-oligomerization and autonomous signalling although the underlying mechanisms remain unclear. Affected entities are candidates for therapy with JAK2 signalling inhibitors. Among 200 peripheral T-cell lymphomas surveyed, we identified only two with JAK2 amplification and none with JAK2 translocations, confirming their rarity in T-cell neoplasias. Here we describe the genomic, transcriptional and signalling characteristics of PCM1-JAK2 formed by t(8;9)(p22;p24) in cell lines established at indolent and aggressive phases of a cutaneous T-cell lymphoma. To investigate signalling, PCM1-JAK2 was subjected to lentiviral knockdown which inhibited 7 genes most upregulated in t(8;9) cells, notably SOCS2/3. SOCS3, but not SOCS2, was also upregulated in a chronic eosinophilic leukemia bearing PCM1-JAK2. Conversely, expression of GATA3, a key T-cell developmental gene silenced in aggressive phase cells, was partially restored by PCM1-JAK2 knockdown. Activation of the tumor suppressor SOCS3 by PCM1-JAK2 may follow structural alteration of JAK2 affecting the ternary complex it forms with SOCS3 and receptor proteins. Treatment with JAK2 inhibitor (TG101348) to which MAC-1/2A/2B cells were conspicuously sensitive mimicked knockdown results, highlighting JAK2 as the active moiety. PCM1-JAK2 signalling required pSTAT5 as reported for JAK2V617F or ETV6/TEL-JAK2, thus extending the paradigm of STAT5 activation by JAK2 alterations in hematopoietic malignancies. MAC-1/2A/2B are the first JAK2– translocation cell line models. Our data support further investigation of SOCS2/3 as signalling effectors, prognostic indicators and potential therapeutic targets in cancers with JAK2 rearrangements. Disclosures: No relevant conflicts of interest to declare.