Expression and genetic polymorphism of necroptosis related protein RIPK1 is correlated with severe hepatic ischemia-reperfusion injury and prognosis after hepatectomy in hepatocellular carcinoma patients

Roles of RIPK1 as a stress sentinel coordinating cell survival and immunogenic cell death

Cell death and inflammation are closely linked arms of the innate immune response to combat infection and tissue malfunction. Recent advancements in our understanding of the intricate signals originating from dying cells have revealed that cell death serves as more than just an end point. It facilitates the exchange of information between the dying cell and cells of the tissue microenvironment, particularly immune cells, alerting and recruiting them to the site of disturbance. Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is emerging as a critical stress sentinel that functions as a molecular switch, governing cellular survival, inflammatory responses and immunogenic cell death signalling. Its tight regulation involves multiple layers of post-translational modifications. In this Review, we discuss the molecular mechanisms that regulate RIPK1 to maintain homeostasis and cellular survival in healthy cells, yet drive cell death in a context-dependent manner. We address how RIPK1 mutations or aberrant regulation is associated with inflammatory and autoimmune disorders and cancer. Moreover, we tease apart what is known about catalytic and non-catalytic roles of RIPK1 and discuss the successes and pitfalls of current strategies that aim to target RIPK1 in the clinic.

Multi-omics analysis reveals the panoramic picture of necroptosis-related regulators in pan-cancer

Background: Unlike apoptosis, necroptosis is a tightly regulated form of programmed cell death (PCD) that occurs in a caspase-independent manner and is mainly triggered by receptor-interacting serine/threonine-protein kinases RIPK1 and RIPK3 and the RIPK3 substrate mixed-lineage kinase domain-like protein (MLKL). A growing body of evidence has documented that necroptosis, as a novel therapeutic strategy to overcome apoptosis resistance, has potential pro- or anti-tumoral effects in tumorigenesis, metastasis, and immunosurveillance. However, comprehensive multi-omics studies on regulators of necroptosis from a pan-cancer perspective are lacking.

Methods: In the present study, a pan-cancer multi-omics analysis of necroptosis-related regulators was performed by integrating over 10,000 multi-dimensional cancer genomic data across 33 cancer types from TCGA, 481 small-molecule drug response data from CTRP, and normal tissue data from GTEx. Pan-cancer pathway-level analyses of necroptosis were conducted by gene set variation analysis (GSVA), including differential expression, clinical relevance, immune cell infiltration, and regulation of cancer-related pathways.

Results: Genomic alterations and abnormal epigenetic modifications were associated with dysregulated gene expression levels of necroptosis-related regulators. Changes in the gene expression levels of necroptosis-related regulators significantly influenced cancer progression, intratumoral heterogeneity, alterations in the immunological condition, and regulation of cancer marker-related pathways. These changes, in turn, caused differences in potential drug sensitivity and the prognosis of patients.

Conclusion: Necroptosis-related regulators are expected to become novel biomarkers of prognosis and provide a fresh perspective on cancer diagnosis and treatment.

Construction and Validation of a Necroptosis-Related Signature Associated With the Immune Microenvironment in Liver Hepatocellular Carcinoma

Background: Liver hepatocellular carcinoma (LIHC) is a widespread and often deadly neoplasm. There is increasing evidence that necroptosis mediates numerous tumor-associated behaviors, as well as the regulation of the tumor microenvironment, suggesting its use as a biomarker for tumor prognosis.

Methods: Data on mRNA expression and necroptosis regulators were acquired from the TCGA and KEGG databases, respectively. Clinical liver hepatocellular carcinoma (LIHC) patient data and information on the expression of necroptosis regulators were processed by unsupervised cluster analysis was performed on LIHC patients together with necroptotic regulator expression and, differentially expressed necroptosis-related genes (DENRGs) were identified by comparing the two clusters. A signature based on eight DENRGs was constructed and verified through independent data sets, and its relationship with the tumor microenvironment was investigated.

Results: Unsupervised cluster analysis demonstrated inherent immune differences among LIHC patients. In all, 1,516 DENRGs were obtained by comparison between the two clusters. In the training set, the final eight genes obtained by univariate, LASSO, and multivariate Cox regression were utilized for constructing the signature. The survival and receiver operating characteristic (ROC) curve achieved satisfactory results in both sets. The high-risk group was characterized by greater immune infiltration and poor prognosis. The results of survival analysis based on the expression of eight DENRGs further confirmed the signature.

Conclusion: We established and validated a risk signature based on eight DERNGs related to the tumor microenvironment. This provides a possible explanation for the different clinical effects of immunotherapy and provides a novel perspective for predicting tumor prognosis in LIHC.

[Practice of laparoscopic hepatectomy in primary care facilities in China: surgical planning, surgical techniques and postoperative management]

With the development and application of laparoscopic hepatectomy in major medical centers, domestic and foreign guidelines have summarized the indications, surgical techniques and operational procedures of the surgery. But in primary care facilities, where the surgical equipment are available, laparoscopic hepatectomy is performed only in a small number of cases and the progress of its application remains slow. The reasons possibly lie in the failure of a full understanding of the surgery, the lack of anatomical knowledge of laparoscopic hepatectomy, the lack of close multidisciplinary cooperation in the perioperative period and insufficient training of laparoscopic technology. In this review, we elaborate on three aspects of laparoscopic hepatectomy: preoperative planning, surgical techniques and postoperative management. Before the operation, the surgeons should fully understand the anatomical structure of the liver and select appropriate cases considering both the difficulty of operation and the surgical experience of the surgeons. During the operation, the position of the patient and the layout of the stamping card should be appropriate, and the central venous pressure needs to be well controlled in close cooperation with the anesthesiologist. The surgeons should be proficient at the techniques of liver suspension and pulling and at the use of ultrasonic knife, and select correct techniques for management of bleeding and the control of blood flow in and out of the liver. The patient should receive postoperative management with standard enhanced recovery after surgery (ERAS) protocols. These experiences may help to improve the practice of laparoscopic hepatectomy in local hospitals or primary care facilities.

Single Nucleotide Polymorphisms in Neonatal Necrotizing Enterocolitis

The etiopathogenesis of necrotizing enterocolitis (NEC) remains unclear, but increasing information suggests that the risk and severity of NEC may be influenced by single nucleotide polymorphisms in many genes. In this article, we have reviewed gene variations that have either been specifically identified in NEC or have been noted in other inflammatory bowel disorders with similar histopathological abnormalities. We present evidence from our own peer-reviewed laboratory studies and data from an extensive literature search in the databases PubMed, EMBASE, and Scopus. To avoid bias in the identification of existing studies, search keywords were short-listed both from our own studies and from PubMed's Medical Subject Heading (MeSH) thesaurus.

Guidelines for Regulated Cell Death Assays: A Systematic Summary, A Categorical Comparison, A Prospective

Over the past few years, the field of regulated cell death continues to expand and novel mechanisms that orchestrate multiple regulated cell death pathways are being unveiled. Meanwhile, researchers are focused on targeting these regulated pathways which are closely associated with various diseases for diagnosis, treatment, and prognosis. However, the complexity of the mechanisms and the difficulties of distinguishing among various regulated types of cell death make it harder to carry out the work and delay its progression. Here, we provide a systematic guideline for the fundamental detection and distinction of the major regulated cell death pathways following morphological, biochemical, and functional perspectives. Moreover, a comprehensive evaluation of different assay methods is critically reviewed, helping researchers to make a reliable selection from among the cell death assays. Also, we highlight the recent events that have demonstrated some novel regulated cell death processes, including newly reported biomarkers (e.g., non-coding RNA, exosomes, and proteins) and detection techniques.

Single-nucleotide polymorphism rs17548629 in RIPK1 gene may be associated with lung cancer in a young and middle-aged Han Chinese population

Background

Genetic biomarkers of lung cancer (LC) susceptibility may provide a basis for treatment and prevention. This study analyzed an association between SNPs (single nucleotide polymorphisms) in the complementary region of the 3′-UTR (3′ untranslated region) of microRNAs of the gene RIPK1 (receptor-interacting serine/threonine-protein kinase 1) and LC among an adult Han Chinese population aged younger than 60 years. Also explored the effect of regulation of the RIPK1 gene via rs17548629 and microRNA-1197 on the occurrence of LC.

Methods

RIPK1 variants (rs17548629, rs77736895) were determined in a population of 571 adults (younger than 60 years) with LC, and 609 gender- and age-matched healthy individuals. Bioinformatics methods predicted the microRNAs bound to rs17548629. Dual luciferase reporter assay was performed to confirm the presence of both rs17548629 and the predicted microRNA.

Results

A mutation (T) of rs17548629 was associated with an increased risk for LC in this population under the codominant and recessive genetic models. The risk of lung adenocarcinoma in rs17548629 mutant carriers was 1.769-fold higher than that of the wildtype. In vitro, the luciferase activity of co-transfected mutant psiCHECK2-RIPK1 and microRNA-1197 mimics was less than that of the group transfected with microRNA-1197 mimics only. Factorial analysis indicated interactions between microRNA-1197 mimics and genotypes of rs17548629.

Conclusion

A mutation (T) of rs17548629 may increase the risk of LC/lung adenocarcinoma in adult Han populations younger than 60 years. When carrying the T allele, rs17548629 may be the target of hsa-miR-1197. This mutation may affect transcriptional level of the RIPK1, thereby promoting the occurrence of LC.

Overexpressed microRNA-494 represses RIPK1 to attenuate hippocampal neuron injury in epilepsy rats by inactivating the NF-κB signaling pathway

OBJECTIVE

The effects of microRNAs (miRNAs) have been identified in epilepsy (Ep) in recent years, our research was focused on the functions of miR-494 in Ep and its inner mechanisms.

METHODS

The Ep modeled rats induced by lithium chloride-pilocarpine were treated with agomir-miR-494 or RIPK1-siRNA. The pathology of rat hippocampal tissues was observed. Expression of miR-494, receptor-interacting protein kinase 1 (RIPK1) and nuclear factor-kappaB (NF-κB) p65 was assessed by RT-qPCR and Western blot analysis. The hippocampal neurons of epileptic rats were successfully modeled, which were transfected with miR-494 mimics or RIPK1-siRNA to determine neurons' proliferation ability and cell apoptosis. The target relation between miR-494 and RIPK1 was measured by bioinformatics website and dual luciferase gene reporter assay.

RESULTS

The expression of miR-494 was reduced, while the expression of RIPK1 and NF-κB p65 was amplified in hippocampus of Ep rats. Elevated miR-494 repressed the expression of RIPK1 to ameliorate the hippocampal neuron injury, accelerate neuronal proliferation, and restrain neuronal apoptosis via inactivating the NF-κB signaling pathway, causing a deceleration of Ep development. Furthermore, amplified RIPK1 was able to reverse the amelioration of neuronal injury in Ep rats which was contributed by upregulated miR-494.

CONCLUSION

We found in this study that elevated miR-494 repressed RIPK1, causing an inactivation of the NF-κB signaling pathway and acceleration of cell proliferation, and suppression of apoptosis of hippocampal neurons in Ep rats, thereby attenuating the neuron injury and Ep development. Our research may provide novel targets for the therapy of Ep.

Micro-RNA-21 rs1292037 A>G polymorphism can predict hepatocellular carcinoma prognosis (HCC), and plays a key role in cell proliferation and ischemia-reperfusion injury (IRI) in HCC cell model of IRI

OBJECTIVES

To assess the predictive function of miR-21 rs1292037 A greater than G polymorphism in survival and ischemia-reperfusion injury (IRI) in hepatocellular carcinoma (HCC) patients.

METHODS

The experiment was carried out between July 2018 and July 2019, whereas the prospective clinical study was carried out between January 2014 and January 2019. In this study, 62 HCC patients with hepatitis B virus (HBV), 17 HCC patients without HBV, and 13 healthy controls were investigated. Micro-RNA-21 levels in the blood were identified using quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and allele specific PCR for miR-21 rs1292037. Partial hepatectomy was performed in all patients, and the tumor development indicators and survival time were evaluated in a subsequent follow-up. Cell-based simulated IRI model of HCC huh7 cell line was used to determine the functions of miR-21 with respect to IRI and proliferation.

RESULTS

Micro-RNA-21 levels were significantly increased in HCC patients. Furthermore, an miR- 21 rs1292037 A greater than G polymorphism was found to be significantly associated with HCC prognosis and severity of liver injury after hepatectomy. In vitro study revealed that miR-21 might prevent IRI from occurring, and can induce proliferation in HCC huh7 cells. These functions of miR-21 were demonstrated to be triggered by IL-12A inhibition.

CONCLUSION

Micro-RNA-21 rs1292037 A greater than G polymorphism can predict IRI and tumor progression by regulating the miR-21/IL-12A.axis.

Molecular Insights into the Mechanism of Necroptosis: The Necrosome As a Potential Therapeutic Target

Necroptosis, or regulated necrosis, is an important type of programmed cell death in addition to apoptosis. Necroptosis induction leads to cell membrane disruption, inflammation and vascularization. It plays important roles in various pathological processes, including neurodegeneration, inflammatory diseases, multiple cancers, and kidney injury. The molecular regulation of necroptotic pathway has been intensively studied in recent years. Necroptosis can be triggered by multiple stimuli and this pathway is regulated through activation of receptor-interacting protein kinase 1 (RIPK1), RIPK3 and pseudokinase mixed lineage kinase domain-like (MLKL). A better understanding of the mechanism of regulation of necroptosis will further aid to the development of novel drugs for necroptosis-associated human diseases. In this review, we focus on new insights in the regulatory machinery of necroptosis. We further discuss the role of necroptosis in different pathologies, its potential as a therapeutic target and the current status of clinical development of drugs interfering in the necroptotic pathway.

p53 protein expression affected by TP53 polymorphism is associated with the biological behavior and prognosis of low rectal cancer

Low rectal cancer is a subtype of colorectal cancer at a special anatomic site with distinct biological behavior. TP53 is one of the most important cancer suppressor genes, and its structural variation and abnormal expression has been revealed to be associated with multiple cancer types. However, to the best of our knowledge, the association of p53 protein expression with its gene polymorphism, biological behavior and prognosis in low rectal cancer has not been clarified. Therefore, the current study aimed to explore these associations. In the present study, 347 patients with low rectal cancer and 353 controls were enrolled. Kompetitive Allele-Specific Polymerase Chain Reaction was used to detect five polymorphic sites of the TP53 gene (rs1042522, rs12947788, rs1625895, rs2909430 and rs12951053), while immunohistochemistry was used to detect the protein expression of TP53. The associations between p53 protein expression and TP53 polymorphism, biological behavior and prognosis in low rectal cancer were systematically analyzed. In low rectal cancer, p53 protein expression was markedly higher in TP53 rs1042522 mutant carriers compared with that in other genotypes where expression was higher in poorly differentiated, III-IV phase and T3-4 phase tumors, and in III-IV phase female patients. The survival time of patients with low p53 protein expression was evidently longer in females, non-smokers and patients >60 years old. In summary, p53 protein expression was identified to be affected by TP53 rs1042522 polymorphism, and was associated with the biological behavior and prognosis of low rectal cancer. TP53 rs1042522 and the associated protein expression could be used as indicators for biological behavior and prognosis in low rectal cancer.

Necroptosis signaling in liver diseases: An update

The apoptosis alternate cell death pathways are extensively studied in recent years and their significance has been well recognized. With identification of newer cell death pathways, the therapeutic opportunities to modulate cell death have indeed further extended. Necroptosis, among other apoptosis alternate pathways, has been immensely studied recently in different hepatic disease models. Receptor-interacting protein 1 (RIPK1), RIPK3 and mixed lineage kinase domain like (MLKL) seemed to be the key players to mediate necroptosis pathway. Initially, necroptosis seemed to be following the typical pathway. But recently diverse pathways and outcomes have been observed. With recent studies reporting diverse outcomes, the necroptosis signalling has become a lot more interesting and intricate. The typical RIPK1 signalling followed by RIPK3 and MLKL might not always be strictly followed. Although, necroptosis signalling has been intensively investigated in various disease conditions; however, there is still a need to further elaborate and understand the unique scaffolding and kinase properties and other signalling interactions of necroptosis signalling molecules.

Depletion of RIPK1 in hepatocytes exacerbates liver damage in fulminant viral hepatitis

The protein kinase RIPK1 plays a crucial role at the crossroad of stress-induced signaling pathways that affects cell’s decision to live or die. The present study aimed to define the role of RIPK1 in hepatocytes during fulminant viral hepatitis, a worldwide syndrome mainly observed in hepatitis B virus (HBV) infected patients. Mice deficient for RIPK1, specifically in liver parenchymal cells (Ripk1^LPC-KO) and their wild-type littermates (Ripk1^fl/fl), were challenged by either the murine hepatitis virus type 3 (MHV3) or poly I:C, a synthetic analog of double-stranded RNA mimicking viral pathogen-associated molecular pattern. Ripk1^LPC-KO mice developed more severe symptoms at early stage of the MHV3-induced fulminant hepatitis. Similarly, administration of poly I:C only triggered increase of systemic transaminases in Ripk1^LPC-KO mice, reflecting liver damage through induced apoptosis as illustrated by cleaved-caspase 3 labeling of liver tissue sections. Neutralization of TNF-α or prior depletion of macrophages were able to prevent the appearance of apoptosis of hepatocytes in poly I:C-challenged Ripk1^LPC-KO mice. Moreover, poly I:C never induced direct hepatocyte death in primary culture whatever the murine genotype, while it always stimulated an anti-viral response. Our investigations demonstrated that RIPK1 protects hepatocytes from TNF-α secreted from macrophages during viral induced fulminant hepatitis. These data emphasize the potential worsening risks of an HBV infection in people with polymorphism or homozygous amorphic mutations already described for the RIPK1 gene.