MDMX/MDM4 is highly expressed and contributes to cell growth and survival in anaplastic large cell lymphoma.

We hypothesized that murine double minute X (MDMX), a negative p53-regulator, may be involved in dysfunctional p53-signaling in anaplastic large cell lymphoma (ALCL), anaplastic lymphoma kinase (ALK)-positive and ALK-negative, characterized frequently by non-mutated TP53 (wt-p53). By western blot analysis, MDMX was highly expressed in ALK + ALCL and expressed at variable levels in ALK- ALCL cell lines. By immunohistochemistry, high MDMX levels were observed more frequently in ALK + ALCL (36/46; 78%), compared with ALK- ALCL tumors (12/29; 41%) (p < .0018, Mann-Whitney-test). FISH analysis showed MDMX-amplification in 1 of 13 (8%) ALK- ALCL tumors, and low-level MDMX copy gains in 2 of 13 (15%) ALK- ALCL and 3 of 11 (27%) ALK + ALCL tumors. MDMX-pharmacologic inhibition or siRNA-mediated MDMX-silencing were associated with activated p53 signaling, growth inhibition and apoptotic cell death in wt-p53 ALCL cells, providing evidence that targeting MDMX may provide a new therapeutic approach for ALCL patients with wt-p53.

Apolipoprotein A-I (ApoA-I), Immunity, Inflammation and Cancer.

Apolipoprotein A-I (ApoA-I), the major protein component of high-density lipoproteins (HDL) is a multifunctional protein, involved in cholesterol traffic and inflammatory and immune response regulation. Many studies revealing alterations of ApoA-I during the development and progression of various types of cancer suggest that serum ApoA-I levels may represent a useful biomarker contributing to better estimation of cancer risk, early cancer diagnosis, follow up, and prognosis stratification of cancer patients. In addition, recent in vitro and animal studies disclose a more direct, tumor suppressive role of ApoA-I in cancer pathogenesis, which involves anti-inflammatory and immune-modulatory mechanisms. Herein, we review recent epidemiologic, clinicopathologic, and mechanistic studies investigating the role of ApoA-I in cancer biology, which suggest that enhancing the tumor suppressive activity of ApoA-I may contribute to better cancer prevention and treatment.

Neorogioltriol and Related Diterpenes from the Red Alga Laurencia Inhibit Inflammatory Bowel Disease in Mice by Suppressing M1 and Promoting M2-Like Macrophage Responses.

Macrophages are central mediators of inflammation, orchestrating the inflammatory response through the production of cytokines and nitric oxide. Macrophages obtain pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes, which can be modulated by soluble factors, including natural products. Despite the crucial protective role of inflammation, chronic or deregulated inflammation can lead to pathological states, such as autoimmune diseases, metabolic disorders, cardiovascular diseases, and cancer. In this case, we studied the anti-inflammatory activity of neorogioltriol (1) in depth and identified two structurally related diterpenes, neorogioldiol (2), and O11,15-cyclo-14-bromo-14,15-dihydrorogiol-3,11-diol (3), with equally potent activity. We investigated the mechanism of action of metabolites 1⁻3 and found that all three suppressed macrophage activation and promoted an M2-like anti-inflammatory phenotype by inducing expression of Arginase1, MRC1, IRAK-M, the transcription factor C/EBPß, and the miRNA miR-146a. In addition, they suppressed iNOS induction and nitric oxide production. Importantly, treatment of mice with 2 or 3 suppressed DSS-induced colitis by reducing tissue damage and pro-inflammatory cytokine production. Thus, all these three diterpenes are promising lead molecules for the development of anti-inflammatory agents targeting macrophage polarization mechanisms.

TPL2 Kinase Is a Crucial Signaling Factor and Mediator of NKT Effector Cytokine Expression in Immune-Mediated Liver Injury.

Invariant NKT (iNKT) cells represent a subset of innate-like T lymphocytes that function as orchestrators of hepatic inflammation underpinning liver damage. In this study, we demonstrate that TPL2, an MAP3 kinase that has mostly been appreciated for its physiological role in macrophage responses, is a signaling factor in CD3(+)NK1.1(+) iNKT cells and mediator of hepatic inflammation. Genetic ablation of TPL2 in the mouse ameliorates liver injury induced by Con A and impinges on hallmarks of NKT cell activation in the liver without affecting NKT cell development in the thymus. The pivotal role of TPL2 in iNKT cell functions is further endorsed by studies using the iNKT-specific ligand α-galactosylceramide, which causes mild hepatitis in the mouse in a TPL2-dependent manner, including production of the effector cytokines IL-4 and IFN-γ, accumulation of neutrophils and licensing and activation of other immune cell types in the liver. A TPL2 kinase inhibitor mirrors the effects of genetic ablation of TPL2 in vivo and uncovers ERK and Akt as the TPL2-regulated signaling pathways responsible for IL-4 and IFN-γ expression through the activation of the transcription factors JunB and NFAT. Collectively, these findings expand our understanding of the mechanisms of iNKT cell activation and suggest that modulation of TPL2 has the potential to minimize the severity of immune-driven liver diseases.

Enhanced therapeutic anti-tumor immunity induced by co-administration of 5-fluorouracil and adenovirus expressing CD40 ligand.

Bystander immune activation by chemotherapy has recently gained extensive interest and provided support for the clinical use of chemotherapeutic agents in combination with immune enhancers. The CD40 ligand (CD40L; CD154) is a potent regulator of the anti-tumor immune response and recombinant adenovirus (RAd)-mediated CD40L gene therapy has been effective in various cancer models and in man. In this study we have assessed the combined effect of local RAd-CD40L and 5-fluorouracil (5-FU) administration on a syngeneic MB49 mouse bladder tumor model. Whereas MB49 cells implanted into immunocompetent mice responded poorly to RAd-CD40L or 5-FU alone, administration of both agents dramatically decreased tumor growth, increased survival of the mice and induced systemic MB49-specific immunity. This combination treatment was ineffective in athymic nude mice, highlighting an important role for T cell mediated anti-tumor immunity for full efficacy. 5-FU up-regulated the expression of Fas and immunogenic cell death markers in MB49 cells and cytotoxic T lymphocytes from mice receiving RAd-CD40L immunotherapy efficiently lysed 5-FU treated MB49 cells in a Fas ligand-dependent manner. Furthermore, local RAd-CD40L and 5-FU administration induced a shift of myeloid-derived suppressor cell phenotype into a less suppressive population. Collectively, these data suggest that RAd-CD40L gene therapy is a promising adjuvant treatment to 5-FU for the management of bladder cancer.

TPL2 kinase is a suppressor of lung carcinogenesis.

Lung cancer is a heterogeneous disease at both clinical and molecular levels, posing conceptual and practical bottlenecks in defining key pathways affecting its initiation and progression. Molecules with a central role in lung carcinogenesis are likely to be targeted by multiple deregulated pathways and may have prognostic, predictive, and/or therapeutic value. Here, we report that Tumor Progression Locus 2 (TPL2), a kinase implicated in the regulation of innate and adaptive immune responses, fulfils a role as a suppressor of lung carcinogenesis and is subject to diverse genetic and epigenetic aberrations in lung cancer patients. We show that allelic imbalance at the TPL2 locus, up-regulation of microRNA-370, which targets TPL2 transcripts, and activated RAS (rat sarcoma) signaling may result in down-regulation of TPL2 expression. Low TPL2 levels correlate with reduced lung cancer patient survival and accelerated onset and multiplicity of urethane-induced lung tumors in mice. Mechanistically, TPL2 was found to antagonize oncogene-induced cell transformation and survival through a pathway involving p53 downstream of cJun N-terminal kinase (JNK) and be required for optimal p53 response to genotoxic stress. These results identify multiple oncogenic pathways leading to TPL2 deregulation and highlight its major tumor-suppressing function in the lung.

Tumor progression locus 2/Cot is required for activation of extracellular regulated kinase in liver injury and toll-like receptor-induced TIMP-1 gene transcription in hepatic stellate cells in mice.

UNLABELLED: Toll-like receptors (TLRs) function as key regulators of liver fibrosis and are able to modulate the fibrogenic actions of nonparenchymal liver cells. The fibrogenic signaling events downstream of TLRs on Kupffer cells (KCs) and hepatic stellate cells (HSCs) are poorly defined. Here, we describe the MAP3K tumor progression locus 2 (Tpl2) as being important for the activation of extracellular regulated kinase (ERK) signaling in KCs and HSCs responding to stimulation of TLR4 and TLR9. KCs lacking Tpl2 display defects with TLR induction of cytokines interleukin (IL)-1ß, IL-10, and IL-23. tpl2(-/-) HSCs were unable to increase expression of fibrogenic genes IL-1ß and tissue inhibitor of metalloproteinase 1 (TIMP-1), with the latter being the result of defective stimulation of TIMP-1 promoter activity by TLRs. To determine the in vivo relevance of Tpl2 signaling in liver fibrosis, we compared the fibrogenic responses of wild-type (WT) and tpl2(-/-) mice in three distinct models of chronic liver injury. In the carbon tetrachloride and methionine-choline-deficient diet models, we observed a significant reduction in fibrosis in mice lacking Tpl2, compared to WT controls. However, in the bile duct ligation model, there was no effect of tpl2 deletion, which may reflect a lesser role for HSCs in wounding response to biliary injury. CONCLUSION: We conclude that Tpl2 is an important signal transducer for TLR activation of gene expression in KCs and HSCs by the ERK pathway and that suppression of its catalytic activity may be a route toward suppressing fibrosis caused by hepatocellular injuries. (HEPATOLOGY 2013).