RIPK2: New Elements in Modulating Inflammatory Breast Cancer Pathogenesis

Expression of Truncated Products at the 5'-Terminal Region of RIPK2 and Evolutive Aspects that Support Their Biological Importance

Alternative splicing is the process of generating different mRNAs from the same primary transcript, which contributes to increase the transcriptome and proteome diversity. Abnormal splicing has been associated with the development of several diseases including cancer. Given that mutations and abnormal levels of the RIPK2 transcript and RIP-2 protein are frequent in tumors, and that RIP-2 modulates immune and inflammatory responses, we investigated alternative splicing events that result in partial deletions of the kinase domain at the N-terminus of RIP-2. We also investigated the structure and expression of the RIPK2 truncated variants and isoforms in different environments. In addition, we searched data throughout Supraprimates evolution that could support the biological importance of RIPK2 alternatively spliced products. We observed that human variants and isoforms were differentially regulated following temperature stress, and that the truncated transcript was more expressed than the long transcript in tumor samples. The inverse was found for the longer protein isoform. The truncated variant was also detected in chimpanzee, gorilla, hare, pika, mouse, rat, and tree shrew. The fact that the same variant has been preserved in mammals with divergence times up to 70 million years raises the hypothesis that it may have a functional significance.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Receptor-interacting protein kinase 2 is associated with tumor immune infiltration, immunotherapy-related biomarkers, and affects gastric cancer cells growth in vivo

Background: The objective of this study was to analyze the research trend of four RIPK genes (RIPK1, RIPK2, RIPK3, and RIPK4), their expression variations in tumors, and the correlation between RIPK2 expression and immune-related biomarkers in gastric cancer (GC). Methods: The PubMed database was utilized to investigate the research trend surrounding four RIPKs genes in tumors. The ULCAN database was employed to analyze the differential expression of these four RIPKs genes. TCGA data were utilized to examine the association between RIPK2 expression and various factors including tumor immune infiltration and immune-related biomarkers. Lastly, the impact of targeting RIPK2 on the growth of GC cells was confirmed through tumor formation assay, immunohistochemistry, and Tunnel assays. Results: In the field of tumor biology, there has been a sustained increase in research focused on the four RIPKs genes over the past decade. Four RIPKs genes are differentially expressed in a majority of tumors. Furthermore, this investigation has unveiled a connection between the expression of RIPK2 and the infiltration of four immune cells, as well as the presence of RNA methylation modifying enzymes, specifically m1A, m6A, and m5C, in GC. Additionally, RIPK2 expression was associated with the genes related to immune checkpoint regulation, as well as genes associated with immunoinhibitors and immunostimulators. It was also revealed that RIPK2 expression was correlated to immunotherapy response biomarkers, namely MSI and TMB, and tumor stemness. Ultimately, it was demonstrated that targeting the RIPK2 effectively regulated GC cells growth through the suppression of PCNA expression and the induction of apoptosis. Conclusion: The expression of RIPK2 is correlated with immune cell infiltration, RNA methyltransferase activity, tumor stemness, checkpoint-related genes, and immunotherapy-related biomarkers. Suppression of RIPK2 impedes the growth of GC cells in vivo. Consequently, RIPK2 holds promise as a viable immunotherapy target for various types of cancer.

Analysis of alternative splicing in chicken macrophages transfected with overexpression/knockdown of RIP2 gene

Receptor-interacting protein 2 (RIP2) plays a critical role in the transduction of many signaling pathways and is associated with many diseases. Alternative splicing (AS) is an essential and ubiquitous regulatory mechanism of gene expression that contributes to distinct transcript variants and many different kinds of proteins. In this present study, we characterized genome-wide AS events in wild-type chicken macrophages (WT) and RIP2 overexpression/knockdown chicken macrophages (oeRIP2/shRIP2) by high-throughput RNA sequencing technology. A total of 1901, 2061, and 817 differentially expressed (DE) AS genes were identified in the comparison of oeRIP2 vs. WT, oeRIP2 vs. shRIP2, and shRIP2 vs. WT, respectively. These DE AS genes participated in many important KEGG pathways, including regulation of autophagy, Wnt signaling pathway, Ubiquitin mediated proteolysis, MAPK signaling pathway, and Focal adhesion, etc. In conclusion, this research provided a broad atlas of the genome-wide scale of the AS event landscape in RIP2 overexpression/knockdown and wild-type chicken macrophages. This research also provides the theoretical basis of the gene network related to RIP2.

Receptor Interacting Ser/Thr-Protein Kinase 2 as a New Therapeutic Target

Receptor interacting serine/threonine protein kinase 2 (RIPK2) is a downstream signaling molecule essential for the activation of several innate immune receptors, including the NOD-like receptors (NOD1 and NOD2). Recognition of pathogen-associated molecular pattern proteins by NOD1/2 leads to their interaction with RIPK2, which induces release of pro-inflammatory cytokines through the activation of NF-κB and MAPK pathways, among others. Thus, RIPK2 has emerged as a key mediator of intracellular signal transduction and represents a new potential therapeutic target for the treatment of various conditions, including inflammatory diseases and cancer. In this Perspective, first, an overview of the mechanisms that underlie RIPK2 function will be presented along with its role in several diseases. Then, the existing inhibitors that target RIPK2 and different therapeutic strategies will be reviewed, followed by a discussion on current challenges and outlook.

Rational targeting of autophagy in colorectal cancer therapy: From molecular interactions to pharmacological compounds

The abnormal progression of tumors has been a problem for treatment of cancer and therapeutic should be directed towards targeting main mechanisms involved in tumorigenesis in tumors. The genomic mutations can result in changes in biological mechanisms in human cancers. Colorectal cancer is one of the most malignant tumors of gastrointestinal tract and its treatment has been faced some difficulties due to development of resistance in tumor cells and also, their malignant behavior. Hence, new therapeutic modalities for colorectal cancer are being investigated. Autophagy is a "self-digestion" mechanism that is responsible for homeostasis preserving in cells and its aberrant activation/inhibition can lead to tumorigenesis. The current review focuses on the role of autophagy mechanism in colorectal cancer. Autophagy may be associated with increase/decrease in progression of colorectal cancer due to mutual function of this molecular mechanism. Pro-survival autophagy inhibits apoptosis to increase proliferation and survival rate of colorectal tumor cells and it is also involved in cancer metastasis maybe due to EMT induction. In contrast, pro-death autophagy decreases growth and invasion of colorectal tumor cells. The status of autophagy (upregulation and down-regulation) is a determining factor for therapy response in colorectal tumor cells. Therefore, targeting autophagy can increase sensitivity of colorectal tumor cells to chemotherapy and radiotherapy. Interestingly, nanoparticles can be employed for targeting autophagy in cancer therapy and they can both induce/suppress autophagy in tumor cells. Furthermore, autophagy modulators can be embedded in nanostructures in improving tumor suppression and providing cancer immunotherapy.

RIPK2: a promising target for cancer treatment

As an essential mediator of inflammation and innate immunity, the receptor-interacting serine/threonine-protein kinase-2 (RIPK2) is responsible for transducing signaling downstream of the intracellular peptidoglycan sensors nucleotide oligomerization domain (NOD)-like receptors 1 and 2 (NOD1/2), which will further activate nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, leading to the transcription activation of pro-inflammatory cytokines and productive inflammatory response. Thus, the NOD2-RIPK2 signaling pathway has attracted extensive attention due to its significant role in numerous autoimmune diseases, making pharmacologic RIPK2 inhibition a promising strategy, but little is known about its role outside the immune system. Recently, RIPK2 has been related to tumorigenesis and malignant progression for which there is an urgent need for targeted therapies. Herein, we would like to evaluate the feasibility of RIPK2 being the anti-tumor drug target and summarize the research progress of RIPK2 inhibitors. More importantly, following the above contents, we will analyze the possibility of applying small molecule RIPK2 inhibitors to anti-tumor therapy.

RIPK2 promotes the progression of colon cancer by regulating BIRC3-mediated ubiquitination of IKBKG

Colon cancer is a cancer with high morbidity and mortality worldwide. Receptor interacting serine/threonine kinase 2 (RIPK2) has been identified as a proto-oncogene, but its role in colon cancer is largely unknown. Herein, we found that RIPK2 interference could inhibit the proliferation and invasion of colon cancer cells, and promote apoptosis. Baculoviral IAP repeat containing 3 (BIRC3) is an E3 ubiquitin ligase, which was found highly expressed in colon cancer cells. Co-immunoprecipitation (Co-IP) experiments showed that RIPK2 could directly bind with BIRC3. Then, we demonstrated that RIPK2 overexpression promoted the expression of BIRC3, BIRC3 interference could eliminate RIPK2-dependent cell proliferation and invasion, and BIRC3 overexpression rescued the suppressive effect of RIPK2 interference on cell proliferation and invasion. We further identified IKBKG, an inhibitor of nuclear factor kappa B, as a ubiquitination substrate targeted by BIRC3. IKBKG interference could eliminate the inhibitory effect of BIRC3 interference on cell invasion. RIPK2 could promote BIRC3-mediated ubiquitination of IKBKG, inhibit the expression of IKBKG protein, and promote the expression of NF-κB subunits p50 and p65 proteins. In addition, DLD-1 cells transfected with sh-RIPK2 or/and sh-BIRC3 were injected into mice to establish a tumor xenograft model, and we found that administration of sh-RIPK2 or sh-BIRC3 impeded the growth of xenograft tumors in vivo, and co-administration displayed a better inhibitory effect. In general, RIPK2 promotes the progression of colon cancer by promoting BIRC3-mediated ubiquitination of IKBKG and activating the NF-κB signaling pathway.

Blocking RIPK2 Function Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating the AKT and NF-κB Pathways

OBJECTIVE

Inflammation and oxidation brought on by myocardial ischemia-reperfusion (MI/R) injury lead to cardiomyocyte apoptosis and necrosis. The receptor interacting serine/threonine kinase 2 (RIPK2) plays significant roles in oxidative stress and excessive inflammation. The purpose of this research is to examine the roles of RIPK2 in MI/R injury.

METHODS

The in vivo animal model was constructed by acute coronary I/R, and the in vitro cell model was established by oxygen and glucose deprivation/reperfusion (OGD/R)-stimulated cardiomyocyte injury. RIPK2 expression was examined using qRT-PCR and Western blot. CCK-8 was proposed as a method for detecting cell proliferation. ELISA was utilized to measure inflammatory cytokines (TNF-α, IL-6, and IL-1β) and myocardial injury indicators (CK-MB, Mb, cTnI, and LDH). The levels of MDA and ROS were determined by the kit and fluorescent probe. H&E was conducted to assess MI/R injury after silencing of RIPK2.

RESULTS

In MI/R rats and OGD/R-treated H9C2 cardiomyocytes, RIPK2 was overexpressed at both the mRNA and protein levels. RIPK2 inhibition promoted cell proliferation while inhibiting apoptosis, as evidenced by decreased TUNEL-positive cells and cleaved caspase-3. RIPK2 inhibition reduced MDA and ROS levels, as well as the contents of inflammatory factors. RIPK2 silencing reduced CK-MB, Mb, cTnI, and LDH levels in rat serum and alleviated MI/R injury. Furthermore, RIPK2 inhibition increased p-AKT while decreasing NF-B p-p65 expression.

CONCLUSION

Silencing of RIPK2 reduced apoptosis, proinflammatory factors, and oxidative stress in MI/R by activating AKT and suppressing NF-κB signals, suggesting a potential therapeutic strategy for MI/R injury.

Sophora flavescens Aiton methanol extract exerts anti-inflammatory effects via reduction of Src kinase phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora flavescens Aiton (Family: Leguminosae), an herbal plant, has been used in East Asian home remedies for centuries for treating ulcers, skin burns, fevers, and inflammatory disorders. In addition, the dried root of S. flavescens was also applied for antipyretic, analgesic, antihelmintic, and stomachic uses.

AIM OF STUDY

Nonetheless, how this plant can show various pharmacological activities including anti-inflammatory responses was not fully elucidated. In this study, therefore, we aimed to investigate the curative effects of S. flavescens on inflammation and its molecular mechanism.

MATERIALS AND METHODS

For reaching this aim, various in vitro and in vivo experimental models with LPS-treated RAW264.7 cells, HCl/EtOH-induced gastric ulcer, and LPS-triggered lung injury conditions were employed and anti-inflammatory activity of S. flavescens methanol extract (Sf-ME) was also tested. Fingerprinting profile of Sf-ME was identified via LC-MS analysis. Its anti-inflammatory molecular mechanism was also examined by immunoblotting analysis.

RESULTS

Nitric oxide production and mRNA expression levels of iNOS, COX-2, IL-1β, and TNF-α were decreased. Additionally, phosphorylation of Src in the signaling cascade was decreased, and activities of the transcriptional factor NF-κB were reduced as determined by a luciferase reporter assay. Moreover, in vivo, gastritis and lung injury lesions were attenuated by Sf-ME.

CONCLUSION

Taken together, these findings suggest that Sf-ME could be a potential anti-inflammatory therapeutic agent via suppression of Src kinase activity and regulation of IL-1β secretion.

Gene expression profiling of RIP2-knockdown in HD11 macrophages - elucidation of potential pathways (gene network) when challenged with avian pathogenic E.coli (APEC)

BACKGROUND

Receptor interacting serine/threonine kinase 2 (RIP2), ubiquitous in many tissue/cell types, is the key regulator of immune and inflammatory responses for many diseases, including avian pathogenic E. coli (APEC), which causes a wide variety of localized or systemic infections. However, the molecular mechanisms by which RIP2 drives its transcriptional program to affect immune and inflammatory response upon APEC infection remains poorly understood.

RESULTS

In this study, RNA-seq and bioinformatics analyses were used to detect gene expression and new direct/indirect RIP2 targets in the treatments of wild type HD11 cells (WT), RIP2 knockdown cells (shRIP2), APEC stimulation cells (APEC), and RIP2 knockdown cells combined with APEC infection (shRIP2 + APEC). The results revealed that a total of 4691 and 2605 differentially expressed genes (DEGs) were screened in shRIP2 + APEC vs. APEC and shRIP2 vs. WT, respectively. Functional annotation analysis showed that apoptosis, MAPK, p53, Toll-like receptor, and Nod-like receptor signaling pathways were involved in APEC-induced RIP2 knockdown HD11 cells. By analyzing the enriched pathway and gene networks, we identified that several DEGs, including HSP90AB1, BID, and CASP9 were targeted by RIP2 upon APEC infection.

CONCLUSION

As a whole, this study can not only provide data support for constructing gene networks of RIP2 knockdown with APEC challenge but also provide new ideas for improving the immune and inflammatory response.

Identification and Validation of Inflammatory Response-Related Gene Signatures to Predict the Prognosis of Neuroblastoma

Background. Neuroblastoma (NB) is the third most common malignant tumor in children. The inflammation is believed to be closely related to NB patients’ prognosis. However, there is no comprehensive research to study the role of inflammatory response-related gene (IRRG) in NB patients. Methods. We downloaded the gene expression profiles of NB patients from GEO and TARGET database, and the expression of 200 IRRGs was extracted. Then, we performed differentially analysis between INSS stage 4 and INSS stage 4S NB patients. The univariate and multivariate Cox regression analyses were performed to screen out the overall survival- (OS-) and event-free survival- (EFS-) related IRRGs in GSE49710, and two signatures were constructed; both signatures were evaluated by Kaplan-Meier (K-M) survival curve and receiver operating characteristic (ROC) curve. Finally, the TARGET cohort was used to validate IRRG signatures, and the independence of the prognostic IRRG signatures was evaluated by integrating clinical information. Results. We screened out 10 OS-related IRRGs and 11 EFS-related IRRGs. Then, we identified that OS- and EFS-related IRRG signatures and found that the OS and EFS of NB patients in the low-risk group were significantly superior than those in the high-risk group (both $P$ value < 0.0001). The AUC values of 3-, 5-, and 7-year OS are 0.910, 0.933, and 0.921, respectively, and 3-, 5-, and 7-year EFS are 0.840, 0.835, and 0.837, respectively. In addition, we found that both IRRG signatures can be used as independent prognostic indicators for patients with NB. Both IRRG signatures still have good predictive ability in validation cohort. Conclusions. We constructed and validated two prognostic gene signatures based on IRRGs. Our study helped us to better understand the role of inflammation in NB and provided new insights for the prognosis assessment and treatment strategy for NB patients.

High expression of RIPK2 is associated with Taxol resistance in serous ovarian cancer

Background

Taxol resistance in serous ovarian cancer is responsible for its poor prognosis, yet the underlying mechanism is still poorly understood. Thus, we probed the mechanism of Taxol resistance in serous ovarian cancer with multiple bioinformatic methods to provide novel insights into potential therapies.

Methods

The differentially expressed genes (DEGs) in Taxol-sensitive and Taxol-resistant cell lines and their relationship with the overall survival (OS) and progression-free interval (PFI) of ovarian cancer patients were analyzed using gene expression datasets from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The role of receptor interacting serine/threonine kinase 2 (RIPK2) was validated via identification of its coexpressed genes, functional analysis and generation of a protein-protein interaction (PPI) network. The single sample gene set enrichment analysis (ssGSEA) was used to explore immune infiltration, and genomic alterations of RIPK2 were also analyzed via cBio Cancer Genomics Portal (cBioProtal).

Results

RIPK2 was highly expressed in Taxol resistant ovarian cancer cell lines, and its high expression was also linked with shorter OS and PFI in serous ovarian cancer patients. The PPI network analysis and pathway analysis demonstrated that RIPK2 might participate in the positive regulation of NF-κB transcription factor activity. RIPK2 expression was related to tumor microenvironment alterations, which might participate in the formation of Taxol resistance.

Conclusions

Our studies suggested that high expression of RIPK2 is related to Taxol resistance in serous ovarian cancer, and that RIPK2 induces Taxol resistance through NOD1/RIPK2/NF-κB inflammatory pathway activation and tumor microenvironment changes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-022-00986-2.

Activation of RIPK2-mediated NOD1 signaling promotes proliferation and invasion of ovarian cancer cells via NF-κB pathway

The goal of this study was to investigate the role and mechanism of action of nucleotide oligomerization domain receptor 1 (NOD1) in ovarian cancer. Results showed that the expressions of NOD1 and receptor interacting serine/threonine kinase 2 (RIPK2) were notably upregulated in non-metastatic and metastatic ovarian tumors compared with matched non-tumor tissues, and their expression in metastatic tumor tissues was higher than that in non-metastatic tumors. Overexpression of NOD1 facilitated the expression of proliferation-related proteins (PCNA and Ki67) and proliferation and invasion of ovarian cancer cells. Overexpression of NOD1 promoted NF-κB expression and phosphorylation. Importantly, NOD1 bound with RIPK2, and silencing of RIPK2 partly rescued the promotion of NOD1 to NF-κB expression and its phosphorylation. The promotion of NOD1 to ovarian cancer cell proliferation and invasion was partly reversed by RIPK2 silencing. Results from our in vivo study indicate that overexpression of NOD1 accelerated the growth of ovarian cancer tumors, expression of proliferation-related proteins, and activation of NF-κB. However, silencing of NOD1 suppressed tumor growth. In summary, NOD1 facilitates ovarian cancer progression by activating NF-κB signaling by binding to RIPK2. We suggest a new strategy for the treatment of ovarian cancer.

Receptor-Interacting Serine/Threonine-Protein Kinase-2 as a Potential Prognostic Factor in Colorectal Cancer

Background and objectives: Receptor-interacting serine/threonine-protein kinase-2 (RIPK2) is an important mediator in different pathways in the immune and inflammatory response system. RIPK2 was also shown to play different roles in different cancer types; however, in colorectal cancer (CRC), its role is not well established. This study aims at identifying the role of RIPK2 in CRC progression and survival. Materials and methods: Data of patients and mRNA protein expression level of genes associated with CRC (RIPK2, tumor necrosis factor (TNF), TRAF1, TRAF7, KLF6, interlukin-6 (Il6), interlukin-8 (Il8), vascular-endothelial growth factor A (VEGFA), MKI67, TP53, nuclear factor-kappa B (NFKB), NFKB2, BCL2, XIAP, and RELA) were downloaded from the PrognoScan online public database. Patients were divided between low and high RIPK2 expression and different CRC characteristics were studied between the two groups. Survival curves were evaluated using a Kaplan-Meier estimator. The Pearson correlation was used to study the correlation between RIPK2 and the other factors. Statistical analysis was carried out using SPSS version 25.0. The Human Protein Atlas was also used for the relationship between RIPK2 expression in CRC tissues and survival. Differences were considered statistically significant at p < 0.05. Results: A total of 520 patients were downloaded from the PrognoScan database, and RIPK2 was found to correlate with MKI67, TRAF1, KLF6, TNF, Il6, Il8, VEGFA, NFKB2, BCL2, and RELA. High expression of RIPK2 was associated with high expression of VEGFA (p < 0.01) and increased mortality (p < 0.01). Conclusions: In this study, RIPK2 is shown to be a potential prognostic factor in CRC; however, more studies are needed to assess and verify its potential role as a prognostic marker and in targeted therapy.

RIPK2 is an unfavorable prognosis marker and a potential therapeutic target in human kidney renal clear cell carcinoma

Receptor Interacting Serine/Threonine Kinase 2 (RIPK2) is located on chromosome 8q21 and encodes a protein containing a C-terminal caspase activation and recruitment domain (CARD), which is a component of signaling complexes in both the innate and adaptive immune pathways. To estimate the value of RIPK2 in evaluating the prognosis and guiding the targeted therapy for patients with kidney renal clear cell carcinoma (KIRC), we analyzed total 526 KIRC samples from The Cancer Genome Atlas (TCGA) database. Our result showed that RIPK2 was upregulated in KIRC tumor samples compared with normal samples. Cox regression was performed to calculate the hazard ratio of RIPK2 expression as an unfavorable prognosis feature for overall survival. Moreover, RIPK2 expression was positively correlated to the high-risk clinical stage, and metastasis features. The upregulation of RIPK2 was strongly correlated with various immune signaling pathway dysregulations as well as immune phenotypes changes in KIRC patient’s cohort. In addition, inhibition of RIPK2 activity by either shRNA-mediated knockdown or inhibitor significantly reduced kidney cancer cell viability, trans-migration in vitro, and impaired tumor growth in vivo. In conclusion, elevated RIPK2 expression indicates a worse prognosis for KIRC patients and could serve as a potential prognostic biomarker and therapeutic target in kidney cancer.

An Inflammatory Response-Related Gene Signature Can Impact the Immune Status and Predict the Prognosis of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is a highly heterogeneous disease, which makes the prognostic prediction challenging. As part of the active cross-talk between the tumor and the host, inflammatory response in the tumor or its microenvironment could affect prognosis. However, the prognostic value of inflammatory response-related genes in HCC remains to be further elucidated.

Methods

In this study, the mRNA expression profiles and corresponding clinical data of HCC patients were downloaded from the public database. The least absolute shrinkage and selection operator Cox analysis was utilized to construct a multigene prognostic signature in the TCGA cohort. HCC patients from the ICGC cohort were used for validation. Kaplan Meier analysis was used to compare the overall survival (OS) between high- and low-risk groups. Univariate and multivariate Cox analyses were applied to determine the independent predictors for OS. Single-sample gene set enrichment analysis was utilized to calculate the immune cell infiltration score and immune related pathway activity. Gene set enrichment analysis was implemented to conduct GO terms and KEGG pathways. The qRT-PCR and immunohistochemistry were utilized to perform the mRNA and protein expression of prognostic genes between HCC tissues and normal liver tissues respectively.

Results

An inflammatory response-related gene signature model was constructed by LASSO Cox regression analysis. Compared with the low-risk group, patients in the high-risk group showed significantly reduced OS. Receiver operating characteristic curve analysis confirmed the predictive capacity of the prognostic gene signature. Multivariate Cox analysis revealed that the risk score was an independent predictor for OS. Functional analysis indicated that immune status was definitely different between two risk groups, and cancer-related pathways were enriched in high-risk group. The risk score was significantly correlated with tumor grade, tumor stage and immune infiltrate types. The expression levels of prognostic genes were significantly correlated with sensitivity of cancer cells to anti-tumor drugs. Furthermore, the expression of prognostic genes showed significant difference between HCC tissues and adjacent non-tumorous tissues in the separate sample cohort.

Conclusion

A novel signature constructed with eight inflammatory response-related genes can be used for prognostic prediction and impact the immune status in HCC. Moreover, inhibition of these genes may be a therapeutic alternative.

Knockdown of RIPK2 Inhibits Proliferation and Migration, and Induces Apoptosis via the NF-κB Signaling Pathway in Gastric Cancer

RIPK2 is a 62 kDa protein and a member of the receptor interacting protein kinases (RIPK) family. It was previously demonstrated that RIPK2 might play a role in promoting malignant tumor progression; however, the precise function of RIPK2 in the onset and progression of gastric cancer (GC) remains unclear. In the current study, we investigated the role of RIPK2 in GC. First, we explored the expression levels of RIPK2 in multiple cancers, including GC, using a bioinformatics approach. We constructed the RIPK2-associated protein-protein interaction network using the search tool for the retrieval of interacting genes/proteins for gene ontology and Kyoto encyclopedia of genes and genomes analysis. Next, we compared the RIPK2 expression levels between GC cells and normal gastric mucosal epithelial cell (GES-1) using reverse transcription quantitative PCR analysis. We downregulated the expression of RIPK2 in GC cells to determine the effects of RIPK2 on cell growth, migration, and apoptosis. Finally, we used western blotting to investigate the RIPK2 downstream signaling pathway involved in the regulation of GC progression. Our results showed that RIPK2 was overexpressed in various tumor tissues, including GC, compared to non-cancer tissues. Moreover, RIPK2 expression was significantly upregulated in all four GC cell lines (MGC-803,SGC-7901, HGC-27 and AGS) comparing the GES-1 cells. Silencing of RIPK2 suppressed GC cell growth by inhibiting migration, and inducing apoptosis through the nuclear factor-κB (NF-κB) signaling pathway. In summary, we demonstrate that RIPK2 plays an important role in modulating GC cell proliferation, migration, and apoptosis through the NF-κB signaling pathway. Therefore, RIPK2 functions as a potential oncogene. We believe that RIPK2 can be used as a candidate biomarker, as well as a diagnostic tool, and the therapeutic target for GC.

Immune modulating effects of receptor interacting protein 2 (RIP2) in autoinflammation and immunity

Receptor-interacting protein 2 (RIP2) is a kinase that is involved in downstream signaling of nuclear oligomerization domain (NOD)-like receptors NOD1 and 2 sensing bacterial peptidoglycans. RIP2-deficiency or targeting of RIP2 by pharmaceutical inhibitors partially ameliorates inflammatory diseases by reducing pro-inflammatory signaling in response to peptidoglycans. However, RIP2 is widely expressed and interacts with several other proteins suggesting additional functions outside the NOD-signaling pathway. In this review, we discuss the immunological functions of RIP2 and its possible role in autoinflammation and immunity.

Fusobacterium nucleatum Promotes Metastasis in Colorectal Cancer by Activating Autophagy Signaling via the Upregulation of CARD3 Expression

Aims: We aimed to measure the abundance of Fusobacterium nucleatum (F. nucleatum) in colorectal cancer (CRC) tissues from patients and to uncover the function of this bacterium in colorectal tumor metastasis.

Methods: We collected metastatic and non-metastatic CRC tissues to analyze F. nucleatum abundance. Cells were incubated with F. nucleatum or chloroquine (CQ) or were transfected with CARD3-targeting siRNA; the expression of mRNAs and proteins was then measured. CRC cells stably transfected with shRNA-luc were mixed with F. nucleatum and intravenously injected into BALB/cJ mice. APC^Min/+, CARD3^-/-and CARD3^wt C57BL mice were given F. nucleatum; some mice were given azoxymethane (AOM) and dextran sodium sulfate (DSS).

Results: F. nucleatum was abundant in CRC tissues from patients with metastasis. F. nucleatum infection increased CRC cell motility and upregulated the expression of CARD3, LC3-II, Beclin1 and Vimentin, and downregulated the expression of E-cadherin and P62 in CRC cells. These effects were attenuated by treatment with CQ, siCARD3 or both. APC^Min/+ mice gavaged with F. nucleatum developed more aggressive tumors than control mice. After AOM/DSS administration, the colorectums of CARD3^-/- mice had fewer tumors than those of control mice. Tumors from CARD3^-/- mice had lower levels of LC3-II and Beclin1 and higher levels of P62 than those from control mice. BALB/cJ mice injected with both CT26-luc cells and F. nucleatum formed more metastases than control mice. CQ treatment, CARD3 knockdown or both reduced the ability of CT26-luc cells to form metastases in vivo.

Conclusions: F. nucleatum is enriched in CRC tissues from patients with metastasis. F. nucleatum orchestrates CARD3 and autophagy to control CRC metastasis. Measuring and targeting F. nucleatum and its associated pathways will yield approaches for the prevention and treatment of CRC metastasis.

Gene silencing of receptor-interacting protein 2 protects against cigarette smoke-induced acute lung injury

BACKGROUND AND PURPOSE

Chronic obstructive pulmonary disease (COPD) is characterized by progressive alveolar damage and generally irreversible airflow limitation. Nuclear factor-κB (NF-κB) plays a critical role in COPD pathogenesis. Receptor-interacting protein 2 (Rip2), a 60 kDa adaptor protein, is a positive regulator of NF-κB pathway and also an inducible transcriptional product of NF-κB activation. We sought to investigate if Rip2 gene silencing could protect against cigarette smoke (CS)-induced acute lung injury.

EXPERIMENTAL APPROACH

Gene silencing efficacy of Rip2 siRNA was characterized in mouse macrophage and mouse lung epithelial cell lines, and in a CS-induced acute lung injury mouse model. Bronchoalveolar lavage (BAL) fluid cell counts, levels of pro-inflammatory and oxidative damage markers, lung section inflammatory and epithelium thickness scorings, and nuclear NF-κB translocation were measured.

KEY RESULTS

CS was found to upregulate Rip2 level in mouse lungs. Rip2 siRNA was able to suppress Rip2 levels in both macrophage and lung epithelial cell lines and in mouse lungs, block CS extract (CSE)-induced mediator release by the cultured cells, and abate neutrophil counts in BAL fluid from CS-challenged mice. Rip2 siRNA suppressed CS-induced inflammatory and oxidative damage markers, and nuclear p65 accumulation and transcriptional activation in lung tissues. Besides, Rip2 siRNA was able to disrupt CSE-induced NF-κB activation in a NF-κB reporter gene assay.

CONCLUSIONS AND IMPLICATIONS

Taken together, we report for the first time that Rip2 gene silencing ameliorated CS-induced acute lung injury probably via disruption of the NF-κB activity, postulating that Rip2 may be a novel therapeutic target for COPD.