Combined toll-like receptor 3/7/9 deficiency on host cells results in T-cell-dependent control of tumour growth

DLM-GelMA/tumor slice sandwich structured tumor on a chip for drug efficacy testing

The in vitro recapitulation of tumor microenvironment is of great interest to preclinical screening of drugs. Compared with culture of cell lines, tumor organ slices can better preserve the complex tumor architecture and phenotypic activity of native cells, but are limited by their exposure to fluid shear and gradual degradation under perfusion culture. Here, we established a decellularized liver matrix (DLM)-GelMA "sandwich" structure and a perfusion-based microfluidic platform to support long-term culture of tumor slices with excellent structural integrity and cell viability over 7 days. The DLM-GelMA was able to secrete cytokines and growth factors while providing shear protection to the tumor slice via the sandwich structure, leading to the preservation of the tumor microenvironment where immune cells (CD3, CD8, CD68), tumor-associated fibroblasts (α-SMA), and extracellular matrix components (collagen I, fibronectin) were well maintained. Furthermore, this chip presented anti-tumor efficacy at cisplatin (20 μM) on tumor patients, demonstrating our platform's efficacy to design patient-specific treatment regimens. Taken together, the successful development of this DLM-GelMA sandwich structure on the chip could faithfully reflect the tumor microenvironment and immune response, accelerating the screening process of drug molecules and providing insights for practical medicine.

Extracellular vesicles produced by avian pathogenic Escherichia coli (APEC) activate macrophage proinflammatory response and neutrophil extracellular trap (NET) formation through TLR4 signaling

BACKGROUND

Avian pathogenic Escherichia coli (APEC) is the major pathogen causing important avian diseases in poultry. As an important subtype of extraintestinal pathogenic E. coli, APEC has zoonotic potential and is considered a foodborne pathogen. APEC extracellular vesicles (EVs) may play vital roles in the interaction of the pathogen with its host cells. However, the precise roles played by APEC EVs are still not completely clear, especially in immune cells.

RESULTS

In this study, we investigated the relationships between APEC EVs and immune cells. The production and characteristics of the EVs of APEC isolate CT265 were identified. Toll like receptor 4 (TLR4) triggered the cellular immune responses when it interacted with APEC EVs. APEC EVs induced a significant release of proinflammatory cytokines in THP-1 macrophages. APEC EVs induced the macrophage inflammatory response via the TLR4/MYD88/NF-κB signaling pathway, which participated in the activation of the APEC-EV-induced NLRP3 inflammasome. However, the loss of lipopolysaccharide (LPS) from APEC EVs reduced the activation of the NLRP3 inflammasome mediated by TLR4/MYD88/NF-κB signaling. Because APEC EVs activated the macrophage inflammatory response and cytokines release, we speculated that the interaction between APEC EVs and macrophages activated and promoted neutrophil migration during APEC extraintestinal infection. This study is the first to report that APEC EVs induce the formation of neutrophil extracellular traps (NETs) and chicken heterophil extracellular traps. Treatment with APEC EVs induced SAPK/JNK activation in neutrophils. The inhibition of TLR4 signaling suppressed APEC-EV-induced NET formation. However, although APEC EVs activated the immune response of macrophages and initiated NET formation, they also damaged macrophages, causing their apoptosis. The loss of LPS from APEC EVs did not prevent this process.

CONCLUSION

APEC-derived EVs induced inflammatory responses in macrophages and NETs in neutrophils, and that TLR4 was involved in the APEC-EV-activated inflammatory response. These findings provided a basis for the further study of APEC pathogenesis.

Distinct immune and inflammatory response patterns contribute to the identification of poor prognosis and advanced clinical characters in bladder cancer patients

Due to the molecular heterogeneity, most bladder cancer (BLCA) patients show no pathological responses to immunotherapy and chemotherapy yet suffer from their toxicity. This study identified and validated three distinct and stable molecular clusters of BLCA in cross-platform databases based on personalized immune and inflammatory characteristics. H&E-stained histopathology images confirmed the distinct infiltration of immune and inflammatory cells among clusters. Cluster-A was characterized by a favorable prognosis and low immune and inflammatory infiltration but showed the highest abundance of prognosis-related favorable immune cell and inflammatory activity. Cluster-B featured the worst prognosis and high immune infiltration, but numerous unfavorable immune cells exist. Cluster-C had a favorable prognosis and the highest immune and inflammatory infiltration. Based on machine learning, a highly precise predictive model (immune and inflammatory responses signature, IIRS), including FN1, IL10, MYC, CD247, and TLR2, was developed and validated to identify the high IIRS-score group that had a poor prognosis and advanced clinical characteristics. Compared to other published models, IIRS showed the highest AUC in 5 years of overall survival (OS) and a favorable predictive value in predicting 1- and 3- year OS. Moreover, IIRS showed an excellent performance in predicting immunotherapy and chemotherapy's response. According to immunohistochemistry and qRT-PCR, IIRS genes were differentially expressed between tumor tissues with corresponding normal or adjacent tissues. Finally, immunohistochemical and H&E-stained analyses were performed on the bladder tissues of 13 BLCA patients to further demonstrate that the IIRS score is a valid substitute for IIR patterns and can contribute to identifying patients with poor clinical and histopathology characteristics. In conclusion, we established a novel IIRS depicting an IIR pattern that could independently predict OS and acts as a highly precise predictive biomarker for advanced clinical characters and the responses to immunotherapy and chemotherapy.

During early stages of cancer, neutrophils initiate anti-tumor immune responses in tumor-draining lymph nodes

Tumor-draining lymph nodes (LNs) play a crucial role during cancer spread and in initiation of anti-cancer adaptive immunity. Neutrophils form a substantial population of cells in LNs with poorly understood functions. Here, we demonstrate that, during head and neck cancer (HNC) progression, tumor-associated neutrophils transmigrate to LNs and shape anti-tumor responses in a stage-dependent manner. In metastasis-free stages (N0), neutrophils develop an antigen-presenting phenotype (HLA-DR⁺CD80⁺CD86⁺ICAM1⁺PD-L1^-) and stimulate T cells (CD27⁺Ki67^highPD-1^-). LN metastases release GM-CSF and via STAT3 trigger development of PD-L1⁺ immunosuppressive neutrophils, which repress T cell responses. The accumulation of neutrophils in T cell-rich zones of LNs in N0 constitutes a positive predictor for 5-year survival, while increased numbers of neutrophils in LNs of N1-3 stages predict poor prognosis in HNC. These results suggest a dual role of neutrophils as essential regulators of anti-cancer immunity in LNs and argue for approaches fostering immunostimulatory activity of these cells during cancer therapy.

IFNAR1 Deficiency Impairs Immunostimulatory Properties of Neutrophils in Tumor-Draining Lymph Nodes

Tumor-draining lymph nodes (TDLNs) are the first organs where the metastatic spread of different types of cancer, including head and neck cancer (HNC), occurs and have therefore high prognostic relevance. Moreover, first anti-cancer immune responses have been shown to be initiated in such LNs via tumor-educated myeloid cells. Among myeloid cells present in TDLNs, neutrophils represent a valuable population and considerably participate in the activation of effector lymphocytes there. Tumor-supportive or tumor-inhibiting activity of neutrophils strongly depends on the surrounding microenvironment. Thus, type I interferon (IFN) availability has been shown to prime anti-tumor activity of these cells. In accordance, mice deficient in type I IFNs show elevated tumor growth and metastatic spread, accompanied by the pro-tumoral neutrophil bias. To reveal the mechanism responsible for this phenomenon, we have studied here the influence of defective type I IFN signaling on the immunoregulatory activity of neutrophils in TDLNs. Live imaging of such LNs was performed using two-photon microscopy in a transplantable murine HNC model. Catchup^IVM-red and Ifnar1^-/- (type I IFN receptor- deficient) Catchup^IVM-red mice were used to visualize neutrophils and to assess their interaction with T-cells in vivo. We have evaluated spatiotemporal patterns of neutrophil/T-cell interactions in LNs in the context of type I interferon receptor (IFNAR1) availability in tumor-free and tumor-bearing animals. Moreover, phenotypic and functional analyses were performed to further characterize the mechanisms regulating neutrophil immunoregulatory capacity. We demonstrated that inactive IFNAR1 leads to elevated accumulation of neutrophils in TDLNs. However, these neutrophils show significantly impaired capacity to interact with and to stimulate T-cells. As a result, a significant reduction of contacts between neutrophils and T lymphocytes is observed, with further impairment of T-cell proliferation and activation. This possibly contributes to the enhanced tumor growth in Ifnar1^-/- mice. In agreement with this, IFNAR1-independent activation of downstream IFN signaling using IFN-λ improved the immunostimulatory capacity of neutrophils in TDLNs and contributed to the suppression of tumor growth. Our results suggest that functional type I IFN signaling is essential for neutrophil immunostimulatory capacity and that stimulation of this signaling may provide a therapeutic opportunity in head and neck cancer patients.

Cross-talks in colon cancer between RAGE/AGEs axis and inflammation/immunotherapy

The tumour microenvironment is the result of the activity of many types of cells in various metabolic states, whose metabolites are shared between cells. This cellular complexity results in an availability profile of nutrients and reactive metabolites such as advanced glycation end products (AGE). The tumour microenvironment is not favourable to immune cells due to hypoxia and for the existence of significant competition between various types of cells for a limited nutrient pool. However, it is now known that cancer cells can influence the host's immune reaction through the expression and secretion of numerous molecules. The microenvironment can therefore present itself in different patterns that contribute to shaping immune surveillance. Colorectal cancer (CRC) is one of the most important causes of death in cancer patients. Recently, immunotherapy has begun to give encouraging results in some groups of patients suffering from this neoplasm. The analysis of literature data shows that the RAGE (Receptor for advanced glycation end products) and its numerous ligands contribute to connect the energy metabolic pathway, which appears prevalently disconnected by mitochondrial running, with the immune reaction, conditioned by local microbiota and influencing tumour growth. Understanding how metabolism in cancer and immune cells shapes response and resistance to therapy, will provide novel potential strategies to increase both the number of tumour types treated by immunotherapy and the rate of immunotherapy response. The analysis of literature data shows that an immunotherapy approach based on the knowledge of RAGE and its ligands is not only possible, but also desirable in the treatment of CRC.

Nucleic Acid Sensors as Therapeutic Targets for Human Disease

Innate immune sensors that detect nucleic acids are attractive targets for therapeutic intervention because of their diverse roles in many disease processes. In detecting RNA and DNA from either self or non-self, nucleic acid sensors mediate the pathogenesis of many autoimmune and inflammatory conditions. Despite promising pre-clinical data and investigational use in the clinic, relatively few drugs targeting nucleic acid sensors are approved for therapeutic use. Nevertheless, there is growing appreciation for the untapped potential of nucleic acid sensors as therapeutic targets, driven by the need for better therapies for cancer, infectious diseases, and autoimmune disorders. This review highlights the diverse mechanisms by which nucleic acid sensors are activated and exert their biological effects in the context of various disease settings. We discuss current therapeutic strategies utilizing agonists and antagonists targeting nucleic acid sensors to treat infectious disease, cancer, and autoimmune and inflammatory disorders.

TLR9 Deficiency in B Cells Promotes Immune Tolerance via Interleukin-10 in a Type 1 Diabetes Mouse Model

Toll-like receptor 9 (TLR9) is highly expressed in B cells, and B cells are important in the pathogenesis of type 1 diabetes (T1D) development. However, the intrinsic effect of TLR9 in B cells on β-cell autoimmunity is not known. To fill this knowledge gap, we generated NOD mice with a B-cell-specific deficiency of TLR9 (TLR9^fl/fl/CD19-Cre+ NOD). The B-cell-specific deletion of TLR9 resulted in near-complete protection from T1D development. Diabetes protection was accompanied by an increased proportion of interleukin-10 (IL-10)-producing B cells. We also found that TLR9-deficient B cells were hyporesponsive to both innate and adaptive immune stimuli. This suggested that TLR9 in B cells modulates T1D susceptibility in NOD mice by changing the frequency and function of IL-10-producing B cells. Molecular analysis revealed a network of TLR9 with matrix metalloproteinases, tissue inhibitor of metalloproteinase-1, and CD40, all of which are interconnected with IL-10. Our study has highlighted an important connection of an innate immune molecule in B cells to the immunopathogenesis of T1D. Thus, targeting the TLR9 pathway, specifically in B cells, may provide a novel therapeutic strategy for T1D treatment.

Signaling Through Nucleic Acid Sensors and Their Roles in Inflammatory Diseases

Recognition of pathogen-derived nucleic acids by pattern-recognition receptors (PRRs) is essential for eliciting antiviral immune responses by inducing the production of type I interferons (IFNs) and proinflammatory cytokines. Such responses are a prerequisite for mounting innate and pathogen-specific adaptive immune responses. However, host cells also use nucleic acids as carriers of genetic information, and the aberrant recognition of self-nucleic acids by PRRs is associated with the onset of autoimmune or autoinflammatory diseases. In this review, we describe the mechanisms of nucleic acid sensing by PRRs, including Toll-like receptors, RIG-I-like receptors, and DNA sensor molecules, and their signaling pathways as well as the disorders caused by uncontrolled or unnecessary activation of these PRRs.

The Lipid Metabolic Landscape of Cancers and New Therapeutic Perspectives

Lipid metabolism reprograming, as a hallmark of malignancy, has received renewed interest in recent years in such areas as energy sources, cell membrane components, and signaling molecules involved in the rapid tumor growth and the adaptation to the tumor microenvironment. Lipid metabolism deregulation in cancer involves multiple aspects, including an increased lipid uptake, endogenous de novo fatty acid synthesis, fatty acid oxidation, and cholesterol accumulation, thereby promoting tumor growth and progression. Recent advances in the understanding of specific metabolic alterations in cancer reveal novel pathogenesis mechanisms and a growing number of drugs targeting lipid metabolism have been applied in anti-tumor therapy. Thus, this review discusses the lipid metabolic landscape of cancers and the interplay with oncogenic signaling, and summarizes potential therapeutic targets to improve the therapeutic efficiency in cancer patients, in order to provide more reference and thinking for the treatment of lipid metabolism of cancer patients.

Reversible Protein Conjugation on Live Cell Surfaces by Specific Recognition between Coiled-Coil Motifs of Natural Amino Acid Sequences

In this study, we propose a reversible covalent conjugation method for peptides, proteins, and even live cells based on specific recognition between natural amino acid sequences. Two heptad sequences can specifically recognize each other and induce the formation of a disulfide bond between cysteine residues. We show the covalent bond formation and dissociation between peptides and proteins in cell-free conditions and on the surface of live cells. Because heptad sequences consist of natural amino acids, they are expressed in cells without additional preparation and can be used to selectively conjugate peptides, proteins, and cells.

Autophagy, the innate immune response and cancer

Autophagy is a cellular degradation and recycling system, which can interact with components of innate immune signalling pathways to enhance pathogen clearance, in both immune and nonimmune cells. Whilst this interaction is often beneficial for pathogen clearance, it can have varying outcomes in regard to tumorigenesis. Autophagy and the innate immune response can have both pro- and antitumorigenic effects at different stages of tumorigenesis due to the plastic nature of the tumour microenvironment (TME). Although both of these components have been studied in isolation as potential therapeutic targets, there has been less research concerning the interaction between autophagy and the innate immune response within the TME. As the innate immune response is critical for the formation of an effective antitumour adaptive immune response, targeting autophagy pathways in both tumour cells and innate immune cells could enhance tumour clearance. Within tumour cells, autophagy pathways are intertwined with pattern recognition receptor (PRR), inflammatory and cell death pathways, and therefore can alter the immunogenicity of the TME and development of the antitumour immune response. In innate immune cells, autophagy components can have autophagy-independent roles in functional pathways, and therefore could be valuable targets for enhancing immune cell function in the TME and immunotherapy. This review highlights the individual importance of autophagy and the innate immune response to tumorigenesis, and also explains the complex interactions between these pathways in the TME.

Plasmacytoid dendritic cells regulate colitis-associated tumorigenesis by controlling myeloid-derived suppressor cell infiltration

Toll-like receptor (TLR)3 and TLR7 are important for stimulating plasmacytoid dendritic cells (pDCs), which secrete type I interferon. Mice deficient for TLR3 and TLR7 (TLR3^-/-TLR7^-/-) reportedly exhibit deteriorated colitis because of impaired pDCs. However, the role of pDCs in tumorigenesis-associated inflammation progression has not been studied. We treated wild-type or TLR3^-/-TLR7^-/- mice with dextran sulfate sodium (DSS) and/or azoxymethane (AOM) and examined colon mucosa, measured body weight and colon length of mice, and examined pDC and myeloid-derived suppressor cell (MDSC) accumulation. Further, we depleted pDCs in AOM/DSS-treated wild-type mice by treating them with anti-PDCA-1 antibodies. We found that MDSCs significantly increased, while pDCs decreased in TLR3^-/-TLR7^-/- mice. Moreover, TLR3^-/-TLR7^-/- mice developed colitis-associated colon cancer following AOM/DSS treatment. Additionally, we showed that a defect in TLR7 of pDCs is responsible for the aggravation of colitis-associated colon cancer. Further, we showed that TLR7 ligand mitigates colitis-associated colon cancer. Collectively, our results demonstrate that gut pDCs play a crucial role in reducing colorectal cancer development via the regulation of infiltrating MDSCs.

Hepatoma cell-intrinsic TLR9 activation induces immune escape through PD-L1 upregulation in hepatocellular carcinoma

A TLR9 agonist in combination with a PD-1 inhibitor produced powerful antitumor responses in a clinical trial despite TLR9 agonists as monotherapies failing to generate systemic antitumor immune responses due to immunosuppressive effects. However, the mechanism involved in the improved response induced by their combination remains unknown. Methods: Subcutaneous and orthotopic Hepa1-6 tumor model was used for single-drug and combined-drug treatment. We used TLR9 agonist stimulation or lentiviral vectors to overexpress TLR9 and activate TLR9 signaling. We next investigated the crosstalk between PARP1 autoPARylation and ubiquitination and between STAT3 PARylation and phosphorylation mediated by TLR9. Tissue chips were used to analyze the relationships among TLR9, PARP1, p-STAT3 and PD-L1 expression. Results: In this study, we found that the TLR9 agonist in combination with anti-PD-1 therapy or anti-PD-L1 therapy yielded an additive effect that inhibited HCC growth in mice. Mechanistically, we found that TLR9 promoted PD-L1 transcription by enhancing STAT3 Tyr705 phosphorylation. Then, we observed that TLR9 negatively regulated PARP1 expression, which mediated a decrease in STAT3 PARylation and an increase in STAT3 Tyr705 phosphorylation. Moreover, we found that TLR9 enhanced PARP1 autoPARylation by inhibiting PARG expression, which then promoted the RNF146-mediated ubiquitination and subsequent degradation of PARP1. Finally, we observed positive associations between TLR9 and p-STAT3 (Tyr705) or PD-L1 expression and negative associations between TLR9 and PARP1 in HCC patient samples. Conclusions: We showed that hepatoma cell-intrinsic TLR9 activation regulated the crosstalk between PARP1 autoPARylation and ubiquitination and between STAT3 PARylation and phosphorylation, which together upregulated PD-L1 expression and finally induces immune escape. Therefore, combination therapy with a TLR9 agonist and an anti-PD-1 antibody or anti-PD-L1 had much better antitumor efficacy than either monotherapy in HCC.

Tumor-Derived Peptidoglycan Recognition Protein 2 Predicts Survival and Antitumor Immune Responses in Hepatocellular Carcinoma

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is linked to immunosuppression. Relieving immunosuppression has been an attractive strategy to improve the efficacy of cancer immunotherapy. Peptidoglycan recognition protein 2 (PGLYRP2) is a pattern recognition receptor which is specifically expressed in liver and implicated in the regulation of innate immunity and immunosurveillance. However, the role of hepatic PGLYRP2 in modulating immune responses against HCC remains to be investigated.

APPROACH AND RESULTS

In this study, we investigated whether PGLYRP2 is able to influence HCC progression through regulating host antitumor immune responses. We demonstrated that PGLYRP2 was down-regulated in HCC, which was linked with poor prognosis in patients (P < 0.001). PGLYRP2 overexpression in HCC cells significantly enhanced antitumor immune responses in immune-competent mice and elevated immune response rates of peripheral blood mononuclear cells against HCC. Mechanistically, DNA methyltransferase 3A-mediated promoter hypermethylation was responsible for the down-regulation of PGLYRP2 in HCC. PGLYRP2 promoted production of chemokine (C-C motif) ligand 5 (CCL5) in HCC through binding to the CCL5 promoter, which contributed to the enhanced antitumor immunity.

CONCLUSIONS

We provide evidence that tumor-derived PGLYRP2 acts as a candidate biomarker for adequate immune response against HCC and improved patient outcomes, indicating the importance of hepatic PGLYRP2 in cancer immunosurveillance and in designing immunotherapeutic approaches.

Distinct Spatio-Temporal Dynamics of Tumor-Associated Neutrophils in Small Tumor Lesions

Across a majority of cancer types tumor-associated neutrophils (TAN) are linked with poor prognosis. However, the underlying mechanisms, especially the intratumoral behavior of TAN, are largely unknown. Using intravital multiphoton imaging on a mouse model with neutrophil-specific fluorescence, we measured the migration of TAN in distinct compartments of solid tumor cell lesions in vivo. By longitudinally quantifying the infiltration and persistence of TAN into growing tumors in the same animals, we observed cells that either populated the peripheral stromal zone of the tumor (peritumoral TAN) or infiltrated into the tumor core (intratumoral TAN). Intratumoral TAN showed prolonged tumor-associated persistence and reduced motility compared to peritumoral TAN, whose velocity increased with tumor progression. Selective pharmacological blockade of CXCR2 receptors using AZD5069 profoundly inhibited recruitment of TAN into peritumoral regions, while intratumoral infiltration was only transiently attenuated and rebounded at later time points. Our findings unravel distinct spatial dynamics of TAN that are partially and differentially regulated via the CXCR2 signaling pathway.

Therapeutic Cancer Vaccines-T Cell Responses and Epigenetic Modulation

There is great interest in developing efficient therapeutic cancer vaccines, as this type of therapy allows targeted killing of tumor cells as well as long-lasting immune protection. High levels of tumor-infiltrating CD8⁺ T cells are associated with better prognosis in many cancers, and it is expected that new generation vaccines will induce effective production of these cells. Epigenetic mechanisms can promote changes in host immune responses, as well as mediate immune evasion by cancer cells. Here, we focus on epigenetic modifications involved in both vaccine-adjuvant-generated T cell immunity and cancer immune escape mechanisms. We propose that vaccine-adjuvant systems may be utilized to induce beneficial epigenetic modifications and discuss how epigenetic interventions could improve vaccine-based therapies. Additionally, we speculate on how, given the unique nature of individual epigenetic landscapes, epigenetic mapping of cancer progression and specific subsequent immune responses, could be harnessed to tailor therapeutic vaccines to each patient.

Bystander T Cells: A Balancing Act of Friends and Foes

T cell responses are essential for appropriate protection against pathogens. T cell immunity is achieved through the ability to discriminate between foreign and self-molecules, and this relies heavily on stringent T cell receptor (TCR) specificity. Recently, bystander activated T lymphocytes, that are specific for unrelated epitopes during an antigen-specific response, have been implicated in diverse diseases. Numerous infection models have challenged the classic dogma of T cell activation as being solely dependent on TCR and major histocompatibility complex (MHC) interactions, indicating an unappreciated role for pathogen-associated receptors on T cells. We discuss here the specific roles of bystander activated T cells in pathogenesis, shedding light on the ability of these cells to modulate disease severity independently from TCR recognition.

Trial Watch: Toll-like receptor agonists in cancer immunotherapy

Toll-like receptor (TLR) agonists demonstrate therapeutic promise as immunological adjuvants for anticancer immunotherapy. To date, three TLR agonists have been approved by US regulatory agencies for use in cancer patients. Additionally, the potential of hitherto experimental TLR ligands to mediate clinically useful immunostimulatory effects has been extensively investigated over the past few years. Here, we summarize recent preclinical and clinical advances in the development of TLR agonists for cancer therapy.

Sipa1 deficiency unleashes a host-immune mechanism eradicating chronic myelogenous leukemia-initiating cells

Chronic myelogenous leukemia (CML) caused by hematopoietic stem cells expressing the Bcr-Abl fusion gene may be controlled by Bcr-Abl tyrosine kinase inhibitors (TKIs). However, CML-initiating cells are resistant to TKIs and may persist as minimal residual disease. We demonstrate that mice deficient in Sipa1, which encodes Rap1 GTPase-activating protein, rarely develop CML upon transfer of primary hematopoietic progenitor cells (HPCs) expressing Bcr-Abl, which cause lethal CML disease in wild-type mice. Resistance requires both T cells and nonhematopoietic cells. Sipa1^−/− mesenchymal stroma cells (MSCs) show enhanced activation and directed migration to Bcr-Abl⁺ cells in tumor tissue and preferentially produce Cxcl9, which in turn recruits Sipa1^−/− memory T cells that have markedly augmented chemotactic activity. Thus, Sipa1 deficiency uncovers a host immune mechanism potentially capable of eradicating Bcr-Abl⁺ HPCs via coordinated interplay between MSCs and immune T cells, which may provide a clue for radical control of human CML.

Chronic myelogenous leukemia (CML)-initiating cells are resistant to kinase inhibitors. Here the authors show that deficiency of the Rap1 GTPase-activating protein Sipa1 in the tumor microenvironment releases an immune response that eradicates CML-initiating cells via interplay between stromal and T cells.

IFI16 restoration in hepatocellular carcinoma induces tumour inhibition via activation of p53 signals and inflammasome

OBJECTIVE

Interferon-inducible 16 (IFI16) is known to involve in p53-dependent tumour suppression and also the formation of inflammasome, which function, however, remains controversy during carcinogenesis as a pattern recognition receptor for tumour death-derived free DNA. In this study, we investigated the anti-tumour role of IFI16 in hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Hepatocellular carcinoma tissues (n = 20) and corresponding non-neoplastic tissues (n = 20) were collected to determine the expression of IFI16. After the transfection of pcDNA3.1-IFI16 into Huh7 and SMMC7721 cells in vitro, the influence of IFI16 overexpression on cell vitality, colony formation, apoptosis and migration were analysed. The role effect of IFI16 in vivo was further investigated.

RESULTS

The expression of IFI16 was significantly decreased in tumour tissues and cell lines. Overexpression of IFI16 induced decrease of cell vitality, colony formation and increased apoptosis with impaired ability of migration. Mechanistically, IFI16 could activate p53 at Ser15 to up-regulate the p21^WAF1/CIP1 level to inhibit tumour growth and migration, which was restored by the p53 inhibitor Pifithrin-α (20 μmol/L). Moreover, IFI16-induced tumour cell death promoted the recruitment of inflammasome complex to enhance tumour inhibition, but the caspase-1 inhibitor Ac-YVAD-CMK (50 μmol/L) could suppress this process in HCC. The results in vivo indicated that restored expression of IFI16 in tumour cells effectively promote tumour regression, which could be partly abrogated by the inhibition of activation of p53 signals or induced inflammasome.

CONCLUSION

IFI16 is a tumour suppressor in HCC via activation of p53 signals and inflammasome.

Aberrant control of NF-κB in cancer permits transcriptional and phenotypic plasticity, to curtail dependence on host tissue: molecular mode

The role of the transcription factor NF-κB in shaping the cancer microenvironment is becoming increasingly clear. Inflammation alters the activity of enzymes that modulate NF-κB function, and causes extensive changes in genomic chromatin that ultimately drastically alter cell-specific gene expression. NF-κB regulates the expression of cytokines and adhesion factors that control interactions among adjacent cells. As such, NF-κB fine tunes tissue cellular composition, as well as tissues' interactions with the immune system. Therefore, NF-κB changes the cell response to hormones and to contact with neighboring cells. Activating NF-κB confers transcriptional and phenotypic plasticity to a cell and thereby enables profound local changes in tissue function and composition. Research suggests that the regulation of NF-κB target genes is specifically altered in cancer. Such alterations occur not only due to mutations of NF-κB regulatory proteins, but also because of changes in the activity of specific proteostatic modules and metabolic pathways. This article describes the molecular mode of NF-κB regulation with a few characteristic examples of target genes.