Inhibition of aberrantly overexpressed Polo-like kinase 4 is a potential effective treatment for DNA damage repair-deficient uterine leiomyosarcoma.

PURPOSE: Uterine leiomyosarcoma (LMS) is an aggressive sarcoma and a subset of which exhibit DNA repair defects. Polo-like kinase 4 (PLK4) precisely modulates mitosis, and its inhibition causes chromosome missegregation and increased DNA damage. We hypothesize that PLK4 inhibition is an effective LMS treatment. EXPERIMENTAL DESIGN: Genomic profiling of clinical uterine LMS samples was performed, and homologous recombination (HR) deficiency scores were calculated. PLK4 inhibitor (CFI-400945) with and without an ataxia telangiectasia mutated (ATM) inhibitor (AZD0156) were tested in vitro on gynecological sarcoma cell lines SK-UT-1, and SKN, and SK-LMS-1. Findings were validated in vivo using the SK-UT-1 xenograft model in Balb/c nude mouse model. The effects of CFI-400945 were also evaluated in a BRCA2 knockout SK-UT-1 cell line. The mechanisms of DNA repair were analyzed using a DNA damage reporter assay. RESULTS: Uterine LMS had a high HR deficiency score, overexpressed PLK4 mRNA, and displayed mutations in genes responsible for DNA repair. CFI-400945 demonstrated effective antitumor activity in vitro and in vivo. The addition of AZD0156 resulted in drug synergism, largely due to a preference for nonhomologous end-joining (NHEJ) DNA repair. Compared to wild-type cells, BRCA2 knockouts were more sensitive to PLK4 inhibition when both HR and NHEJ repairs were impaired. CONCLUSIONS: Uterine LMS with DNA repair defects is sensitive to PLK4 inhibition because of the effects of chromosome missegregation and increased DNA damage. Loss-of-function BRCA2 alterations or pharmacological inhibition of ATM enhanced the efficacy of PLK4 inhibitor. Genomic profiling of an advanced-stage or recurrent uterine LMS may guide therapy.

Inhibition of PLK4 remodels histone methylation and activates the immune response via the cGAS-STING pathway in TP53-mutated AML.

Acute myeloid leukemia (AML) with TP53 mutation is one of the most lethal cancers and portends an extremely poor prognosis. Based on in silico analyses of druggable genes and differential gene expression in TP53-mutated AML, we identified pololike kinase 4 (PLK4) as a novel therapeutic target and examined its expression, regulation, pathogenetic mechanisms, and therapeutic potential in TP53-mutated AML. PLK4 expression was suppressed by activated p53 signaling in TP53 wild-type AML and was increased in TP53-mutated AML cell lines and primary samples. Short-term PLK4 inhibition induced DNA damage and apoptosis in TP53 wild-type AML. Prolonged PLK4 inhibition suppressed the growth of TP53-mutated AML and was associated with DNA damage, apoptosis, senescence, polyploidy, and defective cytokinesis. A hitherto undescribed PLK4/PRMT5/EZH2/H3K27me3 axis was demonstrated in both TP53 wild-type and mutated AML, resulting in histone modification through PLK4-induced PRMT5 phosphorylation. In TP53-mutated AML, combined effects of histone modification and polyploidy activated the cGAS-STING pathway, leading to secretion of cytokines and chemokines and activation of macrophages and T cells upon coculture with AML cells. In vivo, PLK4 inhibition also induced cytokine and chemokine expression in mouse recipients, and its combination with anti-CD47 antibody, which inhibited the "don't-eat-me" signal in macrophages, synergistically reduced leukemic burden and prolonged animal survival. The study shed important light on the pathogenetic role of PLK4 and might lead to novel therapeutic strategies in TP53-mutated AML.

Nucleolar stress: Molecular mechanisms and related human diseases.

Ribosome biogenesis in the nucleolus is an important process that consumes 80% of a cell's intracellular energy supply. Disruption of this process results in nucleolar stress, triggering the activation of molecular systems that respond to this stress to maintain homeostasis. Although nucleolar stress was originally thought to be caused solely by abnormalities of ribosomal RNA (rRNA) and ribosomal proteins (RPs), an accumulating body of more current evidence suggests that many other factors, including the DNA damage response and oncogenic stress, are also involved in nucleolar stress response signaling. Cells reacting to nucleolar stress undergo cell cycle arrest or programmed death, mainly driven by activation of the tumor suppressor p53. This observation has nominated nucleolar stress as a promising target for cancer therapy. However, paradoxically, some RP mutations have also been implicated in cancer initiation and progression, necessitating caution. In this article, we summarize recent findings on the molecular mechanisms of nucleolar stress and the human ribosomal diseases and cancers that arise in its wake.

Polo-like kinase 4 inhibitor CFI-400945 suppresses liver cancer through cell cycle perturbation and eliciting antitumor immunity.

BACKGROUND AND AIMS: Prognosis of HCC remains poor due to lack of effective therapies. Immune checkpoint inhibitors (ICIs) have delayed response and are only effective in a subset of patients. Treatments that could effectively shrink the tumors within a short period of time are idealistic to be employed together with ICIs for durable tumor suppressive effects. HCC acquires increased tolerance to aneuploidy. The rapid division of HCC cells relies on centrosome duplication. In this study, we found that polo-like kinase 4 (PLK4), a centrosome duplication regulator, represents a therapeutic vulnerability in HCC. APPROACH AND RESULTS: An orally available PLK4 inhibitor, CFI-400945, potently suppressed proliferating HCC cells by perturbing centrosome duplication. CFI-400945 induced endoreplication without stopping DNA replication, causing severe aneuploidy, DNA damage, micronuclei formation, cytosolic DNA accumulation, and senescence. The cytosolic DNA accumulation elicited the DEAD box helicase 41-stimulator of interferon genes-interferon regulatory factor 3/7-NF-κß cytosolic DNA sensing pathway, thereby driving the transcription of senescence-associated secretory phenotypes, which recruit immune cells. CFI-400945 was evaluated in liver-specific p53/phosphatase and tensin homolog knockout mouse HCC models established by hydrodynamic tail vein injection. Tumor-infiltrated immune cells were analyzed. CFI-400945 significantly impeded HCC growth and increased infiltration of cluster of differentiation 4-positive (CD4 + ), CD8 + T cells, macrophages, and natural killer cells. Combination therapy of CFI-400945 with anti-programmed death-1 showed a tendency to improve HCC survival. CONCLUSIONS: We show that by targeting a centrosome regulator, PLK4, to activate the cytosolic DNA sensing-mediated immune response, CFI-400945 effectively restrained tumor progression through cell cycle inhibition and inducing antitumor immunity to achieve a durable suppressive effect even in late-stage mouse HCC.

N-(3,4-dimethoxyphenethyl)-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-amine inhibits bladder cancer progression by suppressing YAP1/TAZ.

Bladder cancer (BlC) is the fourth most common cancer in males worldwide, but few systemic chemotherapy options for its effective treatment exist. The development of new molecularly-targeted agents against BlC is therefore an urgent issue. The Hippo signaling pathway, with its upstream LATS kinases and downstream transcriptional co-activators YAP1 and TAZ, plays a pivotal role in diverse cell functions, including cell proliferation. Recent studies have shown that overexpression of YAP1 occurs in advanced BlCs and is associated with poor patient prognosis. Accessing data from our previous screening of a chemical library of compounds targeting the Hippo pathway, we identified DMPCA (N-(3,4-dimethoxyphenethyl)-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-amine) as an agent able to induce the phosphorylation of LATS1 and YAP1/TAZ in BlC cells, thereby suppressing their viability both in vitro and in mouse xenografts. Our data indicate that DMPCA has a potent anti-tumor effect, and raise the possibility that this agent may represent a new and effective therapeutic option for BlC.

CFI-402257, a TTK inhibitor, effectively suppresses hepatocellular carcinoma.

Deregulation of cell cycle is a typical feature of cancer cells. Normal cells rely on the strictly coordinated spindle assembly checkpoint (SAC) to maintain the genome integrity and survive. However, cancer cells could bypass this checkpoint mechanism. In this study, we showed the clinical relevance of threonine tyrosine kinase (TTK) protein kinase, a central regulator of the SAC, in hepatocellular carcinoma (HCC) and its potential as therapeutic target. Here, we reported that a newly developed, orally active small molecule inhibitor targeting TTK (CFI-402257) effectively suppressed HCC growth and induced highly aneuploid HCC cells, DNA damage, and micronuclei formation. We identified that CFI-402257 also induced cytosolic DNA, senescence-like response, and activated DDX41-STING cytosolic DNA sensing pathway to produce senescence-associated secretory phenotypes (SASPs) in HCC cells. These SASPs subsequently led to recruitment of different subsets of immune cells (natural killer cells, CD4+ T cells, and CD8+ T cells) for tumor clearance. Our mass cytometry data illustrated the dynamic changes in the tumor-infiltrating immune populations after treatment with CFI-402257. Further, CFI-402257 improved survival in HCC-bearing mice treated with anti-PD-1, suggesting the possibility of combination treatment with immune checkpoint inhibitors in HCC patients. In summary, our study characterized CFI-402257 as a potential therapeutic for HCC, both used as a single agent and in combination therapy.

Alantolactone is a natural product that potently inhibits YAP1/TAZ through promotion of reactive oxygen species accumulation.

Yes-associated protein 1 (YAP1) and its paralogue PDZ-binding motif (TAZ) play pivotal roles in cell proliferation, migration, and invasion, and abnormal activation of these TEAD transcriptional coactivators is found in diverse cancers in humans and mice. Targeting YAP1/TAZ signaling is thus a promising therapeutic avenue but, to date, few selective YAP1/TAZ inhibitors have been effective against cancer cells either in vitro or in vivo. We screened chemical libraries for potent YAP1/TAZ inhibitors using a highly sensitive luciferase reporter system to monitor YAP1/TAZ-TEAD transcriptional activity in cells. Among 29 049 low-molecular-weight compounds screened, we obtained nine hits, and the four of these that were the most effective shared a core structure with the natural product alantolactone (ALT). We also tested 16 other structural derivatives of ALT and found that natural ALT was the most efficient at increasing ROS-induced LATS kinase activities and thus YAP1/TAZ phosphorylation. Phosphorylated YAP1/TAZ proteins were subject to nuclear exclusion and proteosomic degradation such that the growth of ALT-treated tumor cells was inhibited both in vitro and in vivo. Our data show for the first time that ALT can be used to target the ROS-YAP pathway driving tumor cell growth and so could be a potent anticancer drug.

TAZ inhibits acinar cell differentiation but promotes immature ductal cell proliferation in adult mouse salivary glands.

There are currently no treatments for salivary gland diseases, making it vital to understand signaling mechanisms operating in acinar and ductal cells so as to develop regenerative therapies. To date, little work has focused on elucidating the signaling cascades controlling the differentiation of these cell types in adult mammals. To analyze the function of the Hippo-TAZ/YAP1 pathway in adult mouse salivary glands, we generated adMOB1DKO mice in which both MOB1A and MOB1B were TAM-inducibly deleted when the animals were adults. Three weeks after TAM treatment, adMOB1DKO mice exhibited smaller submandibular glands (SMGs) than controls with a decreased number of acinar cells and an increased number of immature dysplastic ductal cells. The mutants suffered from reduced saliva production accompanied by mild inflammatory cell infiltration and fibrosis in SMGs, similar to the Sjogren's syndrome. MOB1-deficient acinar cells showed normal proliferation and apoptosis but decreased differentiation, leading to an increase in acinar/ductal bilineage progenitor cells. These changes were TAZ-dependent but YAP1-independent. Biochemically, MOB1-deficient salivary epithelial cells showed activation of the TAZ/YAP1 and ß-catenin in ductal cells, but reduced SOX2 and SOX10 expression in acinar cells. Thus, Hippo-TAZ signaling is critical for proper ductal and acinar cell differentiation and function in adult mice.

The role of Hippo-YAP signaling in squamous cell carcinomas.

The Hippo-YAP pathway regulates organ size, tissue homeostasis, and tumorigenesis in mammals. In response to cell density, external mechanical pressure, and/or other stimuli, the Hippo core complex controls the translocation of YAP1/TAZ proteins to the nucleus and thereby regulates cell growth. Abnormal upregulation or nuclear localization of YAP1/TAZ occurs in many human malignancies and promotes their formation, progression, and metastasis. A key example is squamous cell carcinoma (SCC) genesis. Many risk factors and crucial signals associated with SCC development in various tissues accelerate YAP1/TAZ accumulation, and mice possessing constitutively activated YAP1/TAZ show immediate carcinoma in situ (CIS) formation in these tissues. Because CIS onset is so rapid in these mutants, we propose that many SCCs initiate and progress when YAP1 activity is sustained and exceeds a certain oncogenic threshold. In this review, we summarize the latest findings on the roles of YAP1/TAZ in several types of SCCs. We also discuss whether targeting aberrant YAP1/TAZ activation might be a promising strategy for SCC treatment.

YAP1 is a potent driver of the onset and progression of oral squamous cell carcinoma.

Head-and-neck squamous cell carcinoma (HNSCC) is the sixth most common group of cancers in the world, and patients have a poor prognosis. Here, we present data indicating that YAP1 may be a strong driver of the onset and progression of oral SCC (OSCC), a major subtype of HNSCC. Mice with tongue-specific deletion of Mob1a/b and thus endogenous YAP1 hyperactivation underwent surprisingly rapid and highly reproducible tumorigenesis, developing tongue carcinoma in situ within 2 weeks and invasive SCC within 4 weeks. In humans, precancerous tongue dysplasia displays YAP1 activation correlating with reduced patient survival. Combinations of molecules mutated in OSCC may increase and sustain YAP1 activation to the point of oncogenicity. Strikingly, siRNA or pharmacological inhibition of YAP1 blocks murine OSCC onset in vitro and in vivo. Our work justifies targeting YAP1 as therapy for OSCC and perhaps HNSCC, and our mouse model represents a powerful tool for evaluating these agents.

Emerging roles of HECT-type E3 ubiquitin ligases in autophagy regulation.

Autophagy is a conserved self-eating process that delivers cytoplasmic material to the lysosome to allow degradation of intracellular components, including soluble, unfolded and aggregated proteins, damaged organelles, and invading microorganisms. Autophagy provides a homeostatic control mechanism and is essential for balancing sources of energy in response to nutrient stress. Autophagic dysfunction or dysregulation has been implicated in several human pathologies, including cancer and neurodegeneration, and its modulation has substantial potential as a therapeutic strategy. Given the relevant clinical and therapeutic implications of autophagy, there is emerging intense interest in the identification of the key factors regulating the components of the autophagic machinery. Various post-translational modifications, including ubiquitylation, have been implicated in autophagy control. The list of the E3 ubiquitin protein ligases involved in the regulation of several steps of the autophagic process is continuously growing. In this review, we will focus on recent advances in the understanding of the role of the homologous to the E6AP carboxyl terminus-type E3 ubiquitin ligases in autophagy control.

Hippo pathway controls cell adhesion and context-dependent cell competition to influence skin engraftment efficiency.

Cell competition is involved in mammalian embryogenesis and tumor elimination and progression. It was previously shown that, whereas NIH3T3 mouse fibroblasts expressing high levels of the yes-associated protein 1(YAP1) target TEA domain family (TEAD) transcription factors become "winners" in cell competitions, Madin-Darby canine kidney cells expressing activated YAP1 become "losers" and are eliminated from culture monolayers. Thus, YAP1's role in cell competitions is clearly context dependent. Here, we show that keratinocytes overexpressing a constitutively activated YAP1 mutant lose in in vitro competitions with control cells conducted in standard tissue culture dishes and undergo apical extrusion. Similarly, cells in which endogenous YAP1 is activated by NF2 knockdown become losers. The YAP1-overexpressing cells exhibit a decrease in cell-matrix adhesion because of defective expression of adhesion molecules such as fibronectin-1. Cell adhesion-mediated proliferation is also impaired. However, because of intrinsic factors, YAP1-expressing cells proliferate faster than control cells when cocultured in dishes impeding cell adhesion. In vivo, Mob1a/b-deficient (YAP1-activated) epidermis, which shows decreased expression of type XVII collagen, cannot be engrafted successfully onto donor mice. YAP1-activated skin grafts shrink away from surrounding control skin, and the epidermis peels off the basement membrane. Our data show that YAP1 activation controls cell competition in part by decreasing cell adhesion.-Nishio, M., Miyachi, Y., Otani, J., Tane, S., Omori, H., Ueda, F., Togashi, H., Sasaki, T., Mak, T. W., Nakao, K., Fujita, Y., Nishina, H., Maehama, T., Suzuki, A. Hippo pathway controls cell adhesion and context-dependent cell competition to influence skin engraftment efficiency.

Parasitic Behavior of Leukemic Cells in Systemic Host Metabolism.

Metabolic reprogramming is a hallmark of cancer cell metabolism. Recently, in Cancer Cell, Ye and colleagues (2018) reported that leukemic cells have the capacity to modulate glucose metabolism in multiple organs of their host, thereby increasing the glucose resources available for malignant cell growth.

Consensus report of the 8 and 9th Weinman Symposia on Gene x Environment Interaction in carcinogenesis: novel opportunities for precision medicine.

The relative contribution of intrinsic genetic factors and extrinsic environmental ones to cancer aetiology and natural history is a lengthy and debated issue. Gene-environment interactions (G x E) arise when the combined presence of both a germline genetic variant and a known environmental factor modulates the risk of disease more than either one alone. A panel of experts discussed our current understanding of cancer aetiology, known examples of G × E interactions in cancer, and the expanded concept of G × E interactions to include somatic cancer mutations and iatrogenic environmental factors such as anti-cancer treatment. Specific genetic polymorphisms and genetic mutations increase susceptibility to certain carcinogens and may be targeted in the near future for prevention and treatment of cancer patients with novel molecularly based therapies. There was general consensus that a better understanding of the complexity and numerosity of G × E interactions, supported by adequate technological, epidemiological, modelling and statistical resources, will further promote our understanding of cancer and lead to novel preventive and therapeutic approaches.

Loss of Mob1a/b in mice results in chondrodysplasia due to YAP1/TAZ-TEAD-dependent repression of SOX9.

Hippo signaling is modulated in response to cell density, external mechanical forces, and rigidity of the extracellular matrix (ECM). The Mps one binder kinase activator (MOB) adaptor proteins are core components of Hippo signaling and influence Yes-associated protein 1 (YAP1) and transcriptional co-activator with PDZ-binding motif (TAZ), which are potent transcriptional regulators. YAP1/TAZ are key contributors to cartilage and bone development but the molecular mechanisms by which the Hippo pathway controls chondrogenesis are largely unknown. Cartilage is rich in ECM and also subject to strong external forces - two upstream factors regulating Hippo signaling. Chondrogenesis and endochondral ossification are tightly controlled by growth factors, morphogens, hormones, and transcriptional factors that engage in crosstalk with Hippo-YAP1/TAZ signaling. Here, we generated tamoxifen-inducible, chondrocyte-specific Mob1a/b-deficient mice and show that hyperactivation of endogenous YAP1/TAZ impairs chondrocyte proliferation and differentiation/maturation, leading to chondrodysplasia. These defects were linked to suppression of SOX9, a master regulator of chondrogenesis, the expression of which is mediated by TEAD transcription factors. Our data indicate that a MOB1-dependent YAP1/TAZ-TEAD complex functions as a transcriptional repressor of SOX9 and thereby negatively regulates chondrogenesis.

A Complex Role for Lipocalin 2 in Bone Metabolism: Global Ablation in Mice Induces Osteopenia Caused by an Altered Energy Metabolism.

Lipocalin 2 (Lcn2) is an adipokine that carries out a variety of functions in diverse organs. We investigated the bone phenotype and the energy metabolism of Lcn2 globally deleted mice (Lcn2-/- ) at different ages. Lcn2-/- mice were largely osteopenic, exhibiting lower trabecular bone volume, lesser trabecular number, and higher trabecular separation when compared to wild-type (WT) mice. Lcn2-/- mice showed a lower osteoblast number and surface over bone surface, and subsequently a significantly lower bone formation rate, while osteoclast variables were unremarkable. Surprisingly, we found no difference in alkaline phosphatase (ALP) activity or in nodule mineralization in Lcn2-/- calvaria osteoblast cultures, while less ALP-positive colonies were obtained from freshly isolated Lcn2-/- bone marrow stromal cells, suggesting a nonautonomous osteoblast response to Lcn2 ablation. Given that Lcn2-/- mice showed higher body weight and hyperphagia, we investigated whether their osteoblast impairment could be due to altered energy metabolism. Lcn2-/- mice showed lower fasted glycemia and hyperinsulinemia. Consistently, glucose tolerance was significantly higher in Lcn2-/- compared to WT mice, while insulin tolerance was similar. Lcn2-/- mice also exhibited polyuria, glycosuria, proteinuria, and renal cortex vacuolization, suggesting a kidney contribution to their phenotype. Interestingly, the expression of the glucose transporter protein type 1, that conveys glucose into the osteoblasts and is essential for osteogenesis, was significantly lower in the Lcn2-/- bone, possibly explaining the in vivo osteoblast impairment induced by the global Lcn2 ablation. Taken together, these results unveil an important role of Lcn2 in bone metabolism, highlighting a link with glucose metabolism that is more complex than expected from the current knowledge. © 2018 American Society for Bone and Mineral Research.

2-HG Inhibits Necroptosis by Stimulating DNMT1-Dependent Hypermethylation of the RIP3 Promoter.

2-hydroxyglutarate-(2-HG)-mediated inhibition of TET2 activity influences DNA hypermethylation in cells harboring mutations of isocitrate dehydrogenases 1 and 2 (IDH1/2). Here, we show that 2-HG also regulates DNA methylation mediated by DNA methyltransferase 1 (DNMT1). DNMT1-dependent hypermethylation of the RIP3 promoter occurred in both IDH1 R132Q knockin mutant mouse embryonic fibroblast (MEFs) and 2-HG-treated wild-type (WT) MEFs. We found that 2-HG bound to DNMT1 and stimulated its association with the RIP3 promoter, inducing hypermethylation that reduces RIP3 protein and consequently impaired RIP3-dependent necroptosis. In human glioma samples, RIP3 protein levels correlated negatively with IDH1 R132H levels. Furthermore, ectopic expression of RIP3 in transformed IDH1-mutated MEFs inhibited the growth of tumors derived from these cells following transplantation into nude mice. Thus, our research sheds light on a mechanism of 2-HG-induced DNA hypermethylation and suggests that impaired necroptosis contributes to the tumorigenesis driven by IDH1/2 mutations.

IDH1 Mutation Promotes Tumorigenesis by Inhibiting JNK Activation and Apoptosis Induced by Serum Starvation.

Two hallmarks of cancer cells are their resistance to apoptosis and ability to thrive despite reduced levels of vital serum components. c-jun N-terminal kinase (JNK) activation is crucial for apoptosis triggered by serum starvation (SS), and isocitrate dehydrogenase 1 (IDH1) mutations are tumorigenic, in part, because they produce the abnormal metabolite 2-hydroxyglutarate (2-HG). However, it is unknown whether 2-HG-induced tumorigenesis is partially due to JNK inhibition and thus defective SS-induced apoptosis. We show here, using IDH1-R132Q knockin mutant mouse cells, that 2-HG inhibits JNK activation induced only by SS and not by UV or doxorubicin, and thus can block apoptosis. Upon SS, Cdc42 normally disrupts mixed lineage kinase 3's (MLK3's) auto-inhibition, triggering the MLK3-MKK4/7-JNK-Bim apoptotic cascade. 2-HG binds to Cdc42 and abolishes its association with MLK3, inactivating MLK3 and apoptosis. Allograft tumor assays in mice demonstrate that this mechanism contributes to tumorigenesis driven by mutant IDH1, a result confirmed by detection of JNK inactivation in human gliomas harboring IDH1-R132H mutations.

Triggering receptor expressed on myeloid cells-1 (TREM-1) deficiency augments BAFF production to promote lupus progression.

Sensing of nucleic acids by pattern recognition receptors is the key for the initiation and development of systemic lupus erythematosus (SLE). Triggering receptor expressed on myeloid cells-1 (TREM-1) is a novel innate immune receptor, which can amplify Toll-like receptor (TLR)-induced inflammatory responses. Although patients with lupus exhibit increased serum levels of soluble TREM-1 (sTREM-1), the role of TREM-1 in SLE remains unknown. In current study, we found serum sTREM-1 levels were significantly increased in lupus patients and positively correlated with disease activity. Additionally, diseased B6.lpr mice had elevated TREM-1 in the serum, spleen, and lymph nodes. To investigate the role of TREM-1 in lupus, we established Trem-1-/-.lpr mice. Trem-1-/-.lpr mice exhibited lower survival rates and more severe lupus symptoms, including elevated proteinuria, serum anti-dsDNA antibody levels, renal immune complex depositions and lymphocyte subpopulation expansions in both the spleen and lymph nodes. Besides, Trem-1-/-.lpr mice expressed higher serum B cell-activating factor (BAFF) levels and lymph node dendritic cells (DCs) were the major source of increased BAFF. Activation of membrane-bound TREM-1 could suppress TLR9-induced BAFF expression in bone marrow-derived DCs of B6.lpr mice. Moreover, levels of sTREM-1, which could act as an antagonist of membrane-bound TREM-1, were positively correlated with levels of BAFF in the sera of lupus patients. Our findings suggest a novel modulatory role of TREM-1 in the pathogenesis of SLE. sTREM-1 production is a useful diagnostic marker and a molecular target for combination therapy of lupus.

A novel TLR2-triggered signalling crosstalk synergistically intensifies TNF-mediated IL-6 induction.

Toll-like receptors (TLR) recognize pathogens and trigger the production of vigorous pro-inflammatory cytokines [such as tumour necrosis factor (TNF)] that induce systemic damages associated with sepsis and chronic inflammation. Cooperation between signals of TLR and TNF receptor has been demonstrated through the participation of TNF receptor 1 (TNFR) adaptors in endotoxin tolerance. Here, we identify a TLR2-mediated synergy, through a MyD88-independent crosstalk, which enhances subsequent TNF-mediated nuclear factor-kappa B activation and interleukin-6 induction. Membrane-associated adaptor MAL conduces the link between TNF receptor-associated factor 6 (TRAF6) and TNFR-associated death domain, leading to a distinctive K63-ubiquitinylated TRAF6 recruitment into TNFR complex. In summary, our results reveal a novel route of TLR signal that synergistically amplifies TNF-mediated responses, indicating an innovative target for inflammation manipulation.