Effects of growth arrest and DNA damage-inducible protein 34 (GADD34) on inflammation-induced colon cancer in mice

PPP1R15A-expressing monocytic MDSCs promote immunosuppressive liver microenvironment in fibrosis-associated hepatocellular carcinoma

Background & Aims

Recent studies demonstrated the importance of fibrosis in promoting an immunosuppressive liver microenvironment and thereby aggressive hepatocellular carcinoma (HCC) growth and resistance to immune checkpoint blockade (ICB), particularly via monocyte-to-monocytic myeloid-derived suppressor cell (M-MDSC) differentiation triggered by hepatic stellate cells (HSCs). We thus aimed to identify druggable targets in these immunosuppressive myeloid cells for HCC therapy.

Methods

M-MDSC signature genes were identified by integrated transcriptomic analysis of a human HSC-monocyte culture system and tumor-surrounding fibrotic livers of patients with HCC. Mechanistic and functional studies were conducted using in vitro-generated and patient-derived M-MDSCs. The therapeutic efficacy of a M-MDSC targeting approach was determined in fibrosis-associated HCC mouse models.

Results

We uncovered over-expression of protein phosphatase 1 regulatory subunit 15A (PPP1R15A), a myeloid cell-enriched endoplasmic reticulum stress modulator, in human M-MDSCs that correlated with poor prognosis and ICB non-responsiveness in patients with HCC. Blocking TGF-β signaling reduced PPP1R15A expression in HSC-induced M-MDSCs, whereas treatment of monocytes by TGF-β upregulated PPP1R15A, which in turn promoted ARG1 and S100A8/9 expression in M-MDSCs and reduced T-cell proliferation. Consistently, lentiviral-mediated knockdown of Ppp1r15a in vivo significantly reduced ARG1+S100A8/9+ M-MDSCs in fibrotic liver, leading to elevated intratumoral IFN-γ+GZMB+CD8+ T cells and enhanced anti-tumor efficacy of ICB. Notably, pharmacological inhibition of PPP1R15A by Sephin1 reduced the immunosuppressive potential but increased the maturation status of fibrotic HCC patient-derived M-MDSCs.

Conclusions

PPP1R15A+ M-MDSC cells are involved in immunosuppression in HCC development and represent a novel potential target for therapies.

Impact and implications

Our cross-species analysis has identified PPP1R15A as a therapeutic target governing the anti-T-cell activities of fibrosis-associated M-MDSCs (monocytic myeloid-derived suppressor cells). The results from the preclinical models show that specific inhibition of PPP1R15A can break the immunosuppressive barrier to restrict hepatocellular carcinoma growth and enhance the efficacy of immune checkpoint blockade. PPP1R15A may also function as a prognostic and/or predictive biomarker in patients with hepatocellular carcinoma.

Investigation of artificial intelligence integrated fluorescence endoscopy image analysis with indocyanine green for interpretation of precancerous lesions in colon cancer

Indocyanine green (ICG) has been used in clinical practice for more than 40 years and its safety and preferential accumulation in tumors has been reported for various tumor types, including colon cancer. However, reports on clinical assessments of ICG-based molecular endoscopy imaging for precancerous lesions are scarce. We determined visualization ability of ICG fluorescence endoscopy in colitis-associated colon cancer using 30 lesions from an azoxymethane/dextran sulfate sodium (AOM/DSS) mouse model and 16 colon cancer patient tissue-samples. With a total of 60 images (optical, fluorescence) obtained during endoscopy observation of mouse colon cancer, we used deep learning network to predict four classes (Normal, Dysplasia, Adenoma, and Carcinoma) of colorectal cancer development. ICG could detect 100% of carcinoma, 90% of adenoma, and 57% of dysplasia, with little background signal at 30 min after injection via real-time fluorescence endoscopy. Correlation analysis with immunohistochemistry revealed a positive correlation of ICG with inducible nitric oxide synthase (iNOS; r > 0.5). Increased expression of iNOS resulted in increased levels of cellular nitric oxide in cancer cells compared to that in normal cells, which was related to the inhibition of drug efflux via the ABCB1 transporter down-regulation resulting in delayed retention of intracellular ICG. With artificial intelligence training, the accuracy of image classification into four classes using data sets, such as fluorescence, optical, and fluorescence/optical images was assessed. Fluorescence images obtained the highest accuracy (AUC of 0.8125) than optical and fluorescence/optical images (AUC of 0.75 and 0.6667, respectively). These findings highlight the clinical feasibility of ICG as a detector of precancerous lesions in real-time fluorescence endoscopy with artificial intelligence training and suggest that the mechanism of ICG retention in cancer cells is related to intracellular nitric oxide concentration.

GADD34 Ablation Exacerbates Retinal Degeneration in P23H RHO Mice

The UPR is sustainably activated in degenerating retinas, leading to translational inhibition via p-eIF2α. Recent findings have demonstrated that ablation of growth arrest and DNA damage-inducible protein 34 (GADD34), a protein phosphatase 1 regulatory subunit permitting translational machinery operation through p-eIF2α elevation, does not impact the rate of translation in fast-degenerating rd16 mice. The current study aimed to validate whether P23H RHO mice degenerating at a slower pace manifest translational attenuation and whether GADD34 ablation impacts the rate of retinal degeneration via further suppression of retinal protein synthesis and apoptotic cell death. For this study, mice were examined with ERG and histological analyses. The molecular assessment was conducted in the naïve and LPS-challenged mice using Western blot and qRT-PCR analyses. Thus, this study demonstrates that the P23H RHO retinas manifest translational attenuation. However, GADD34 ablation resulted in a more prominent p-eIF2a increase without impacting the translation rate. GADD34 deficiency also led to a reduction in scotopic ERG amplitudes and an increased number of TUNEL-positive cells. Molecular analysis revealed that GADD34 deficiency reduces the expression of p-STAT3 and Il-6 while increasing the expression of Tnfa. Overall, the data indicate that GADD34 plays a multifunctional role. Under chronic UPR activation, GADD34 acts as a feedback player, dephosphorylating p-eIF2a, although this role does not seem to be critical. Additionally, GADD34 controls cytokine expression and STAT3 activation. Perhaps these molecular events are particularly important in controlling the pace of retinal degeneration.

Tumor-Associated Inflammation: The Tumor-Promoting Immunity in the Early Stages of Tumorigenesis

Tumorigenesis is a multistage progressive oncogenic process caused by alterations in the structure and expression level of multiple genes. Normal cells are continuously endowed with new capabilities in this evolution, leading to subsequent tumor formation. Immune cells are the most important components of inflammation, which is closely associated with tumorigenesis. There is a broad consensus in cancer research that inflammation and immune response facilitate tumor progression, infiltration, and metastasis via different mechanisms; however, their protumor effects are equally important in tumorigenesis at earlier stages. Previous studies have demonstrated that during the early stages of tumorigenesis, certain immune cells can promote the formation and proliferation of premalignant cells by inducing DNA damage and repair inhibition, releasing trophic/supporting signals, promoting immune escape, and activating inflammasomes, as well as enhance the characteristics of cancer stem cells. In this review, we focus on the potential mechanisms by which immune cells can promote tumor initiation and promotion in the early stages of tumorigenesis; furthermore, we discuss the interaction of the inflammatory environment and protumor immune cells with premalignant cells and cancer stem cells, as well as the possibility of early intervention in tumor formation by targeting these cellular mechanisms.

Spatial Transcriptomic Analysis Using R-Based Computational Machine Learning Reveals the Genetic Profile of Yang or Yin Deficiency Syndrome in Chinese Medicine Theory

Objectives

Yang and Yin are two main concepts responsible for harmonious balance reflecting health conditions based on Chinese medicine theory. Of note, deficiency of either Yang or Yin is associated with disease susceptibility. In this study, we aim to clarify the molecular feature of Yang and Yin deficiency by reanalyzing a transcriptomic data set retrieved from the GEO database using R-based machine learning analyses, which lays a foundation for medical diagnosis, prevention, and treatment of unbalanced Yang or Yin.

Methods

Besides conventional methods for target mining, we took the advantage of spatial transcriptomic analysis using R-based machine learning approaches to elucidate molecular profiles of Yin and Yang deficiency by reanalyzing an RNA-Seq data set (GSE87474) in the GEO focusing on peripheral blood mononuclear cells (PBMCs). The add-on functions in R including GEOquery, DESeq2, WGCNA (target identification with a scale-free topological assumption), Scatterplot3d, Tidyverse, and UpsetR were used. For information in the selected GEO data set, PBMCs representing 20,740 expressed genes were collected from subjects with Yang or Yin deficiency (n = 12 each), based on Chinese medicine-related diagnostic criteria.

Results

The symptomatic gene targets for Yang deficiency (KAT2B, NFKB2, CREBBP, GTF2H3) or Yin deficiency (JUNB, JUND, NGLY1, TNF, RAF1, PPP1R15A) were potentially discovered. CREBBP was identified as a shared key contributive gene regulating either the Yang or Yin deficiency group. The intrinsic molecular characteristics of these specific genes could link with clinical observations of Yang/Yin deficiency, in which Yang deficiency is associated with immune dysfunction tendency and energy deregulation, while Yin deficiency mainly contains oxidative stress, dysfunction of the immune system, and abnormal lipid/protein metabolism.

Conclusion

Our study provides representative gene targets and modules for supporting clinical traits of Yang or Yin deficiency in Chinese medicine theory, which is beneficial for promoting the modernization of Chinese medicine theory. Besides, R-based machine learning approaches adopted in this study might be further applied for investigating the underlying genetic polymorphisms related to Chinese medicine theory.

Modulation of serine/threonine-protein phosphatase 1 (PP1) complexes: A promising approach in cancer treatment

Cancer is the second leading cause of death worldwide. Despite the availability of numerous therapeutic options, tumor heterogeneity and chemoresistance have limited the success of these treatments, and the development of effective anticancer therapies remains a major focus in oncology research. The serine/threonine-protein phosphatase 1 (PP1) and its complexes have been recognized as potential drug targets. Research on the modulation of PP1 complexes is currently at an early stage, but has immense potential. Chemically diverse compounds have been developed to disrupt or stabilize different PP1 complexes in various cancer types, with the objective of inhibiting disease progression. Beneficial results obtained in vitro now require further pre-clinical and clinical validation. In conclusion, the modulation of PP1 complexes seems to be a promising, albeit challenging, therapeutic strategy for cancer.

SRC-3 deficiency protects host from Listeria monocytogenes infection through increasing ROS production and decreasing lymphocyte apoptosis

Listeria monocytogenes is the third major cause of death among food poisoning. Our previous studies have demonstrated that steroid receptor coactivator 3 (SRC-3) plays a critical protective role in host defense against extracellular bacterial pathogens such as Escherichia coli and Citrobacter rodentium. However, its role involved in intracellular bacterial pathogen infection remains unclear. Herein, we found that SRC-3-/- mice are more resistant to L. monocytogenes infection after tail intravenous injection with L. monocytogenes compared with wild-type mice. After infecting with L. monocytogenes, SRC-3-/- mice exhibited decreased mortality rate, decreased bacterial load, less body weight loss, less proinflammatory cytokines and less severe tissue damage compared with wild-type mice. SRC-3-/- mice produced more ROS and decreased L. monocytogenes-induced lymphocyte apoptosis. Mechanically, SRC-3-/- mice displayed decreased expressions of negative regulator of ROS (NRROS) and interferon (IFN)-β and its target genes such as Daxx, Mx1 and TRAIL associated with apoptosis. Taken together, SRC-3 deficiency can protect host from L. monocytogenes infection through increasing ROS production and decreasing lymphocyte apoptosis via affecting the expressions of NRROS and IFN-β.

Genetic Markers of the Host to Predict the Efficacy of Colorectal Cancer Targeted Therapy

The introduction of anti-EGFR (cetuximab and panitumumab) and antiangiogenic (bevacizumab, regorafeninb, ramucirumab, and aflibercept) agents in the therapeutic armamentarium of the metastatic colorectal cancer (CRC) has significantly improved the therapeutic efficacy and patients survival. However, despite the great improvements achieved in the patients life expectation, the high inter-individual heterogeneity in the response to the targeted agents still represent an issue for the management of advanced CRC patients. Even if the role of tumor genetic mutations as predictive markers of drug efficacy has been well-established, the contribution of the host genetic markers is still controversial. Promising results regard the germ-line immune-profile, inflammation and tumor microenvironment. Inherent variations in KRAS 3'UTR region as well as EGF/ EGFR genes were investigated as markers of cetuximab effectiveness. More recently interesting data in the field of anti- EGFR agents were generated also for germ-line variants in genes involved in inflammation (e.g. COX-2, LIFR, IGF1 signaling), immune system (e.g., FCGRs, IL-1RA), and other players of the RAS signaling, including the Hippo pathway related genes (e.g. Rassf, YAP, TAZ). Host genetic variants in VEGF-dependent (i.e., EGF, IGF-1, HIF1α, eNOS, iNOS) and -independent (i.e., EMT cascade, EGFL7) pathways, with specific attention on inflammation and immune system-related factors (e.g., IL-8, CXCR-1/2, CXCR4-CXCL12 axis, TLRs, GADD34, PPP1R15A, ANXA11, MKNK1), were investigated as predictive markers of bevacizumab outcome, generating some promising results. In this review, we aimed to summarize the most recent literature data regarding the potential role of common and rare inhered variants in predicting which CRC patients will benefit more from a specifically targeted drug administration.

A 16-mRNA signature optimizes recurrence-free survival prediction of Stages II and III gastric cancer

High-throughput messenger RNA (mRNA) analysis has become a powerful tool for exploring tumor recurrence or metastasis mechanisms. Here, we constructed a signature to predict the recurrence risk of Stages II and III gastric cancer (GC) patients. A least absolute shrinkage and selection operator method Cox regression model was utilized to construct the signature. Using this method, a 16-mRNA signature was identified to be associated with the relapse-free survival of Stages II and III GCs in training dataset GSE62254 (n = 194). Then this signature was validated in an independent Gene Expression Omnibus cohort GSE26253 (n = 297) and a dataset of The Cancer Genome Atlas (TCGA; n = 235). This classifier could successfully screen out the high-risk Stages II and III GCs in the training cohort (hazard ratio [HR] = 40.91; 95% confidence interval [CI] = 5.58-299.7; p < .0001). Analysis in two independent validation cohorts yielded consistent results (GSE26253: HR = 1.69, 95% CI = 1.17-2.43,; p = .0045; TCGA: HR = 2.01, 95% CI = 1.13-3.56, p = .0146). Cox regression analyses revealed that the risk score derived from this signature was an independent risk factor in Stages II and III GCs. Besides, a nomogram was constructed to serve clinical practice. Through gene set variation analysis, we found several gene sets associated with chemotherapeutic drug resistance and tumor metastasis significantly enriched in high-risk patients. In summary, this 16-mRNA signature can be used as a powerful tool for prognostic evaluation and help clinicians identify high-risk patients.

Inflammation-induced DNA damage, mutations and cancer

The relationships between inflammation and cancer are varied and complex. An important connection linking inflammation to cancer development is DNA damage. During inflammation reactive oxygen and nitrogen species (RONS) are created to combat pathogens and to stimulate tissue repair and regeneration, but these chemicals can also damage DNA, which in turn can promote mutations that initiate and promote cancer. DNA repair pathways are essential for preventing DNA damage from causing mutations and cytotoxicity, but RONS can interfere with repair mechanisms, reducing their efficacy. Further, cellular responses to DNA damage, such as damage signaling and cytotoxicity, can promote inflammation, creating a positive feedback loop. Despite coordination of DNA repair and oxidative stress responses, there are nevertheless examples whereby inflammation has been shown to promote mutagenesis, tissue damage, and ultimately carcinogenesis. Here, we discuss the DNA damage-mediated associations between inflammation, mutagenesis and cancer.

The regulatory protein GADD34 inhibits TRAIL-induced apoptosis via TRAF6/ERK-dependent stabilization of myeloid cell leukemia 1 in liver cancer cells

GADD34 (growth arrest and DNA damage-inducible gene 34) plays a critical role in responses to DNA damage and endoplasmic reticulum stress. GADD34 has opposing effects on different stimuli-induced cell apoptosis events, but the reason for this is unclear. Here, using immunoblotting analyses and various molecular genetic approaches in HepG2 and SMMC-7721 cells, we demonstrate that GADD34 protects hepatocellular carcinoma (HCC) cells from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by stabilizing a BCL-2 family member, myeloid cell leukemia 1 (MCL-1). We found that GADD34 knockdown decreased MCL-1 levels and that GADD34 overexpression up-regulated MCL-1 expression in HCC cells. GADD34 did not affect MCL-1 transcription but enhanced MCL-1 protein stability. The proteasome inhibitor MG132 abrogated GADD34 depletion-induced MCL-1 down-regulation, suggesting that GADD34 inhibits the proteasomal degradation of MCL-1. Furthermore, GADD34 overexpression promoted extracellular signal-regulated kinase (ERK) phosphorylation through a signaling axis that consists of the E3 ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6) and transforming growth factor-β-activated kinase 1 (MAP3K7)-binding protein 1 (TAB1), which mediated the up-regulation of MCL-1 by GADD34. Of note, TRAIL up-regulated both GADD34 and MCL-1 levels, and knockdown of GADD34 and TRAF6 suppressed the induction of MCL-1 by TRAIL. Correspondingly, GADD34 knockdown potentiated TRAIL-induced apoptosis, and MCL-1 overexpression rescued TRAIL-treated and GADD34-depleted HCC cells from cell death. Taken together, these findings suggest that GADD34 inhibits TRAIL-induced HCC cell apoptosis through TRAF6- and ERK-mediated stabilization of MCL-1.

Interaction between RAD51 and MCM Complex Is Essential for RAD51 Foci Forming in Colon Cancer HCT116 Cells

Colon cancer remains one of the most common digestive system malignancies in the World. This study investigated the possible interaction between RAD51 and minichromosome maintenance proteins (MCMs) in HCT116 cells, which can serve as a model system for forming colon cancer foci. The interaction between RAD51 and MCMs was detected by mass spectrometry. Silenced MCM vectors were transfected into HTC116 cells. The expressions of RAD51 and MCMs were detected using Western blotting. Foci forming and chromatin fraction of RAD51 in HCT116 cells were also analyzed. The results showed that RAD51 directly interacted with MCM2, MCM3, MCM5, and MCM6 in colon cancer HTC116 cells. Suppression of MCM2 or MCM6 by shRNA decreased the chromatin localization of RAD51 in HTC116 cells. Moreover, silenced MCM2 or MCM6 decreased the foci forming of RAD51 in HTC116 cells. Our study suggests that the interaction between MCMs and RAD51 is essential for the chromatin localization and foci forming of RAD51 in HCT116 cell DNA damage recovery, and it may be a theoretical basis for analysis of RAD51 in tumor samples of colon cancer patients.

At the crossway of ER-stress and proinflammatory responses

Immune cells detect specific microbes or damage to tissue integrity in order to initiate efficient immune responses. Abnormal accumulation of proteins in the endoplasmic reticulum (ER) can be seen as a sign of cellular malfunction and stress that triggers a collection of conserved emergency rescue programs. These different signaling cascades, which favor ER proteostasis and promote cell survival, are collectively known as the unfolded protein response (UPR). In recent years, a synergy between the UPR and inflammatory cytokine production has been unraveled, with different branches of the UPR entering in a cross-talk with specialized microbe sensing pathways, which turns on or amplify inflammatory cytokines production. Complementary to this synergetic activity, UPR induction alone, can itself be seen as a danger signal, and triggers directly or indirectly inflammation in different cellular and pathological models, this independently of the presence of pathogens. Here, we discuss recent advances on the nature of these cross-talks and how innate immunity, metabolism dysregulation, and ER-signaling pathways intersect in specialized immune cells, such as dendritic cells (DCs), and contribute to the pathogenesis of inflammatory diseases.

Guanabenz inhibits TLR9 signaling through a pathway that is independent of eIF2α dephosphorylation by the GADD34/PP1c complex

Endoplasmic reticulum (ER) stress triggers or amplifies inflammatory signals and cytokine production in immune cells. Upon the resolution of ER stress, the inducible phosphatase 1 cofactor GADD34 promotes the dephosphorylation of the initiation factor eIF2α, thereby enabling protein translation to resume. Several aminoguanidine compounds, such as guanabenz, perturb the eIF2α phosphorylation-dephosphorylation cycle and protect different cell or tissue types from protein misfolding and degeneration. We investigated how pharmacological interference with the eIF2α pathway could be beneficial to treat autoinflammatory diseases dependent on proinflammatory cytokines and type I interferons (IFNs), the production of which is regulated by GADD34 in dendritic cells (DCs). In mouse and human DCs and B cells, guanabenz prevented the activation of Toll-like receptor 9 (TLR9) by CpG oligodeoxynucleotides or DNA-immunoglobulin complexes in endosomes. In vivo, guanabenz protected mice from CpG oligonucleotide-dependent cytokine shock and decreased autoimmune symptom severity in a chemically induced model of systemic lupus erythematosus. However, we found that guanabenz exerted its inhibitory effect independently of GADD34 activity on eIF2α and instead decreased the abundance of CH25H, a cholesterol hydroxylase linked to antiviral immunity. Our results therefore suggest that guanabenz and similar compounds could be used to treat type I IFN-dependent pathologies and that CH25H could be a therapeutic target to control these diseases.

FTY720 (fingolimod) regulates key target genes essential for inflammation in microglial cells as defined by high-resolution mRNA sequencing

Although microglial cells have an essential role in the host defense of the brain, the abnormal activation of microglia can lead to devastating outcomes, such as neuroinflammation and neurodegeneration. Emerging evidence indicates that FTY720 (fingolimod), an FDA-approved drug, has beneficial effects on brain cells in the central nervous system (CNS) and, more recently, immunosuppressive activities in microglia via modulation of the sphingosine 1 phosphate (S1P) 1 receptor. However, the exact molecular aspects of FTY720 contribution in microglia remain largely unaddressed. To understand the molecular mechanisms underlying the roles of FTY720 in microglia, we performed gene expression profiling in resting, FTY720, LPS and LPS + FTY720 challenged primary microglial (PM) cells isolated from 3-day-old ICR mice, and we identified FTY720 target genes and co-regulated modules that were critical in inflammation. By examining RNA sequencing and binding motif datasets from FTY720 suppressed LPS-induced inflammatory mediators, we also identified unexpected relationships between the inducible transcription factors (TFs), motif strength, and the transcription of key inflammatory mediators. Furthermore, we showed that FTY720 controls important inflammatory genes targets by modulating STAT1 and IRF8 levels at their promoter site. Our unprecedented findings demonstrate that FTY720 could be a useful therapeutic application for neuroinflammatory diseases associated with microglia activation, as well as provide a rich resource and framework for future analyses of FTY720 effects on microglia interaction.

New frontiers in the treatment of colorectal cancer: Autophagy and the unfolded protein response as promising targets

Colorectal cancer (CRC), despite numerous therapeutic and screening attempts, still remains a major life-threatening malignancy. CRC etiology entails both genetic and environmental factors. Macroautophagy/autophagy and the unfolded protein response (UPR) are fundamental mechanisms involved in the regulation of cellular responses to environmental and genetic stresses. Both pathways are interconnected and regulate cellular responses to apoptotic stimuli. In this review, we address the epidemiology and risk factors of CRC, including genetic mutations leading to the occurrence of the disease. Next, we discuss mutations of genes related to autophagy and the UPR in CRC. Then, we discuss how autophagy and the UPR are involved in the regulation of CRC and how they associate with obesity and inflammatory responses in CRC. Finally, we provide perspectives for the modulation of autophagy and the UPR as new therapeutic options for CRC treatment.

Silica nanoparticles induce endoplasmic reticulum stress response and activate mitogen activated kinase (MAPK) signalling

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Effects of silica nanoparticles (SiO₂-NPs) were investigated in Huh7 cells.

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SiO₂-NPs induced ER stress response and activated MAPK pathway.

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SiO₂-NPs induced inflammatory reaction by induction of TNF-α.

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Activation of MAPK may lead to activation of AP-1 complex.

Humans may be exposed to engineered silica nanoparticles (SiO₂-NPs) but potential adverse effects are poorly understood, in particular in relation to cellular effects and modes of action. Here we studied effects of SiO₂-NPs on cellular function in human hepatoma cells (Huh7). Exposure for 24 h to 10 and 50 μg/ml SiO₂-NPs led to induction of endoplasmic reticulum (ER) stress as demonstrated by transcriptional induction of DNAJB9, GADD34, CHOP, as well as CHOP target genes BIM, CHAC-1, NOXA and PUMA. In addition, CHOP protein was induced. In addition, SiO₂-NPs induced an inflammatory response as demonstrated by induction of TNF-α and IL-8. Activation of MAPK signalling was investigated employing a PCR array upon exposure of Huh7 cells to SiO₂-NPs. Five of 84 analysed genes, including P21, P19, CFOS, CJUN and KSR1 exhibited significant transcriptional up-regulation, and 18 genes a significant down-regulation. Strongest down-regulation occurred for the proto-oncogene BRAF, MAPK11, one of the four p38 MAPK genes, and for NFATC4. Strong induction of CFOS, CJUN, FRA1 and CMYC was found after exposure to 50 μg/ml SiO₂-NPs for 24 h. To analyse for effects derived from up-regulation of TNF-α, Huh7 cells were exposed to SiO₂-NPs in the presence of the TNF-α inhibitor sauchinone, which reduced the induction of the TNF-α transcript by about 50%. These data demonstrate that SiO₂-NPs induce ER stress, MAPK pathway and lead to inflammatory reaction in human hepatoma cells. Health implications of SiO₂-NPs exposure should further be investigated for a risk assessment of these frequently used nanoparticles.

Circulating DNA and its methylation level in inflammatory bowel disease and related colon cancer

Both of chronic inflammation and abnormal immune in inflammatory bowel disease can induce colon cancer. Previous research showed that cell apoptosis and necrosis become the main source of circulating DNA in the peripheral blood during tumorigenesis that reduced along with methylation degree. However, its role in the process of colitis transforming to colon cancer is not clarified. Drinking 3% DSS was used to establish colitis model, while 3% dextran sodium sulfate (DSS) combined with azo oxidation methane (AOM) intraperitoneal injection was applied to establish colitis related colon cancer model. Circulating DNA and its methylation level in peripheral blood were tested. Morphology observation, HE staining, and p53 and β-catenin expression detection confirmed that drinking 3% DSS and 3% DSS combined with AOM intraperitoneal injection can successfully establish colitis and colitis associated colorectal cancer models. Circulating DNA level in colitis and colon cancer mice increased by gradient compared with control, while significant difference was observed between each other. Circulating DNA methylation level decreased obviously in colitis and colon cancer, and significant difference was observed between each other. Abnormal protein expression, circulating DNA and its methylation level in ulcerative colitis associated colorectal tissues change in gradient, suggesting that circulating DNA and its methylation level can be treated as new markers for colitis cancer transformation that has certain significance to explore the mechanism of human ulcerative colitis canceration.