Epstein-Barr Virus latent membrane protein-1 (LMP1) interacts with the SUMO-conjugating enzyme Ubc9, which induces protein sumoylation and may contribute to LMP1-mediated oncogenesis. After analyzing human lymphoma tissues and EBV-positive cell lines, we now document a strong correlation between LMP1 and sumo-1/2/3 or SUMO-1/2/3 levels, and show that LMP1-induced sumo expression requires the activation of NF-kappaB signaling through CTAR1 and CTAR2. Together, these results point to a second mechanism by which LMP1 dysregulates sumoylation processes and adds EBV-associated lymphomas to the list of malignancies associated with increased SUMO expression.

Pathogen immune responses are profoundly attenuated in fetuses and premature infants, yet the mechanisms underlying this developmental immaturity remain unclear. Here we show transcriptomic, metabolic and polysome profiling and find that monocytes isolated from infants born early in gestation display perturbations in PPAR-$\gamma$-regulated metabolic pathways, limited glycolytic capacity and reduced ribosomal activity. These metabolic changes are linked to a lack of translation of most cytokines and of MALT1 signalosome genes essential to respond to the neonatal pathogen Candida. In contrast, they have little impact on house-keeping phagocytosis functions. Transcriptome analyses further indicate a role for mTOR and its putative negative regulator DNA Damage Inducible Transcript 4-Like in regulating these metabolic constraints. Our results provide a molecular basis for the broad susceptibility to multiple pathogens in these infants, and suggest that the fetal immune system is metabolically programmed to avoid energetically costly, dispensable and potentially harmful immune responses during ontogeny.

Several somatic ribosome defects have recently been discovered in cancer, yet their oncogenic mechanisms remain poorly understood. Here we investigated the pathogenic role of the recurrent R98S mutation in ribosomal protein L10 (RPL10 R98S) found in T-cell acute lymphoblastic leukemia (T-ALL). The JAK-STAT signaling pathway is a critical controller of cellular proliferation and survival. A proteome screen revealed overexpression of several Jak-Stat signaling proteins in engineered RPL10 R98S mouse lymphoid cells, which we confirmed in hematopoietic cells from transgenic Rpl10 R98S mice and T-ALL xenograft samples. RPL10 R98S expressing cells displayed JAK-STAT pathway hyper-activation upon cytokine stimulation, as well as increased sensitivity to clinically used JAK-STAT inhibitors like pimozide. A mutually exclusive mutation pattern between RPL10 R98S and JAK-STAT mutations in T-ALL patients further suggests that RPL10 R98S functionally mimics JAK-STAT activation. Mechanistically, besides transcriptional changes, RPL10 R98S caused reduction of apparent programmed ribosomal frameshifting at several ribosomal frameshift signals in mouse and human Jak-Stat genes, as well as decreased Jak1 degradation. Of further medical interest, RPL10 R98S cells showed reduced proteasome activity and enhanced sensitivity to clinical proteasome inhibitors. Collectively, we describe modulation of the JAK-STAT cascade as a novel cancer-promoting activity of a ribosomal mutation, and expand the relevance of this cascade in leukemia.

ONC201 is a first-in-class, orally active antitumor agent that upregulates cytotoxic TRAIL pathway signaling in cancer cells. ONC201 has demonstrated safety and preliminary efficacy in a first-in-human trial in which patients were dosed every 3 weeks. We hypothesized that dose intensification of ONC201 may impact antitumor efficacy. We discovered that ONC201 exerts dose- and schedule-dependent effects on tumor progression and cell death signaling in vivo. With dose intensification, we note a potent anti-metastasis effect and inhibition of cancer cell migration and invasion. Our preclinical results prompted a change in ONC201 dosing in all open clinical trials. We observed accumulation of activated NK+ and CD3+ cells within ONC201-treated tumors and that NK cell depletion inhibits ONC201 efficacy in vivo, including against TRAIL/ONC201-resistant Bax-/- tumors. Immunocompetent NCR1-GFP mice, in which NK cells express GFP, demonstrated GFP+ NK cell infiltration of syngeneic MC38 colorectal tumors. Activation of primary human NK cells and increased degranulation occurred in response to ONC201. Coculture experiments identified a role for TRAIL in human NK-mediated antitumor cytotoxicity. Preclinical results indicate the potential utility for ONC201 plus anti-PD-1 therapy. We observed an increase in activated TRAIL-secreting NK cells in the peripheral blood of patients after ONC201 treatment. The results offer what we believe to be a unique pathway of immune stimulation for cancer therapy.

Natural killer (NK) cells play a pivotal role in the immune response against infections and malignant transformation, and adopted transfer of NK cells is thought to be a promising therapeutic approach for cancer patients. Previous reports describing the phenotypic features of canine NK cells have produced inconsistent results. Canine NK cells are still defined as non-B and non-T (CD3-CD21-) large granular lymphocytes. However, a few reports have demonstrated that canine NK cells share the phenotypic characteristics of T lymphocytes, and that CD3+CD5dimCD21- lymphocytes are putative canine NK cells. Based on our previous reports, we hypothesized that phenotypic modulation could occur between these two populations during activation. In this study, we investigated the phenotypic and functional differences between CD3+CD5dimCD21- (cytotoxic large granular lymphocytes) and CD3-CD5-CD21- NK lymphocytes before and after culture of peripheral blood mononuclear cells isolated from normal dogs. The results of this study show that CD3+CD5dimCD21- lymphocytes can be differentiated into non-B, non-T NK (CD3-CD5-CD21-TCRalpha$beta$-TCRgamma$delta$-GranzymeB+) lymphocytes through phenotypic modulation in response to cytokine stimulation. In vitro studies of purified CD3+CD5dimCD21- cells showed that CD3-CD5-CD21- cells are derived from CD3+CD5dimCD21- cells through phenotypic modulation. CD3+CD5dimCD21- cells share more NK cell functional characteristics compared with CD3-CD5-CD21- cells, including the expression of T-box transcription factors (Eomes, T-bet), the production of granzyme B and interferon-gamma$, and the expression of NK cell-related molecular receptors such as NKG2D and NKp30. In conclusion, the results of this study suggest that CD3+CD5dimCD21- and CD3-CD5-CD21- cells both contain a subset of putative NK cells, and the difference between the two populations may be due to the degree of maturation.