Notch activity characterizes a common hepatocellular carcinoma subtype with unique molecular and clinicopathologic features

Signaling pathways in liver cancer: pathogenesis and targeted therapy

Liver cancer remains one of the most prevalent malignancies worldwide with high incidence and mortality rates. Due to its subtle onset, liver cancer is commonly diagnosed at a late stage when surgical interventions are no longer feasible. This situation highlights the critical role of systemic treatments, including targeted therapies, in bettering patient outcomes. Despite numerous studies on the mechanisms underlying liver cancer, tyrosine kinase inhibitors (TKIs) are the only widely used clinical inhibitors, represented by sorafenib, whose clinical application is greatly limited by the phenomenon of drug resistance. Here we show an in-depth discussion of the signaling pathways frequently implicated in liver cancer pathogenesis and the inhibitors targeting these pathways under investigation or already in use in the management of advanced liver cancer. We elucidate the oncogenic roles of these pathways in liver cancer especially hepatocellular carcinoma (HCC), as well as the current state of research on inhibitors respectively. Given that TKIs represent the sole class of targeted therapeutics for liver cancer employed in clinical practice, we have particularly focused on TKIs and the mechanisms of the commonly encountered phenomena of its resistance during HCC treatment. This necessitates the imperative development of innovative targeted strategies and the urgency of overcoming the existing limitations. This review endeavors to shed light on the utilization of targeted therapy in advanced liver cancer, with a vision to improve the unsatisfactory prognostic outlook for those patients.

Τ cell-mediated adaptive immunity in the transition from metabolic dysfunction-associated steatohepatitis to hepatocellular carcinoma

Metabolic dysfunction-associated steatohepatitis (MASH) is the progressed version of metabolic dysfunction-associated steatotic liver disease (MASLD) characterized by inflammation and fibrosis, but also a pathophysiological "hub" that favors the emergence of liver malignancies. Current research efforts aim to identify risk factors, discover disease biomarkers, and aid patient stratification in the context of MASH-induced hepatocellular carcinoma (HCC), the most prevalent cancer among MASLD patients. To investigate the tumorigenic transition in MASH-induced HCC, researchers predominantly exploit preclinical animal-based MASH models and studies based on archived human biopsies and clinical trials. Recapitulating the immune response during tumor development and progression is vital to obtain mechanistic insights into MASH-induced HCC. Notably, the advanced complexity behind MASLD and MASH pathogenesis shifted the research focus towards innate immunity, a fundamental element of the hepatic immune niche that is usually altered robustly in the course of liver disease. During the last few years, however, there has been an increasing interest for deciphering the role of adaptive immunity in MASH-induced HCC, particularly regarding the functions of the various T cell populations. To effectively understand the specific role of T cells in MASH-induced HCC development, scientists should urgently fill the current knowledge gaps in this field. Pinpointing the metabolic signature, sketching the immune landscape, and characterizing the cellular interactions and dynamics of the specific T cells within the MASH-HCC liver are essential to unravel the mechanisms that adaptive immunity exploits to enable the emergence and progression of this cancer. To this end, our review aims to summarize the current state of research regarding the T cell functions linked to MASH-induced HCC.

ASPM stabilizes the NOTCH intracellular domain 1 and promotes oncogenesis by blocking FBXW7 binding in hepatocellular carcinoma cells

Notch signaling is aberrantly activated in approximately 30% of hepatocellular carcinoma (HCC), significantly contributing to tumorigenesis and disease progression. Expression of the major Notch receptor, NOTCH1, is upregulated in HCC cells and correlates with advanced disease stages, although the molecular mechanisms underlying its overexpression remain unclear. Here, we report that expression of the intracellular domain of NOTCH1 (NICD1) is upregulated in HCC cells due to antagonism between the E3-ubiquitin ligase F-box/WD repeat-containing protein 7 (FBXW7) and the large scaffold protein abnormal spindle-like microcephaly-associated protein (ASPM) isoform 1 (ASPM-i1). Mechanistically, FBXW7-mediated polyubiquitination and the subsequent proteasomal degradation of NICD1 are hampered by the interaction of NICD1 with ASPM-i1, thereby stabilizing NICD1 and rendering HCC cells responsive to stimulation by Notch ligands. Consistently, downregulating ASPM-i1 expression reduced the protein abundance of NICD1 but not its FBXW7-binding-deficient mutant. Reinforcing the oncogenic function of this regulatory module, the forced expression of NICD1 significantly restored the tumorigenic potential of ASPM-i1-deficient HCC cells. Echoing these findings, NICD1 was found to be strongly co-expressed with ASPM-i1 in cancer cells in human HCC tissues (P < 0.001). In conclusion, our study identifies a novel Notch signaling regulatory mechanism mediated by protein-protein interaction between NICD1, FBXW7, and ASPM-i1 in HCC cells, representing a targetable vulnerability in human HCC.

Molecular mechanisms in MASLD/MASH-related HCC

Liver cancer is the third leading cause of cancer-related deaths and ranks as the sixth most prevalent cancer type globally. NAFLD or metabolic dysfunction-associated steatotic liver disease, and its more severe manifestation, NASH or metabolic dysfunction-associated steatohepatitis (MASH), pose a significant global health concern, affecting approximately 20%-25% of the population. The increased prevalence of metabolic dysfunction-associated steatotic liver disease and MASH is parallel to the increasing rates of obesity-associated metabolic diseases, including type 2 diabetes, insulin resistance, and fatty liver diseases. MASH can progress to MASH-related HCC (MASH-HCC) in about 2% of cases each year, influenced by various factors such as genetic mutations, carcinogen exposure, immune microenvironment, and microbiome. MASH-HCC exhibits distinct molecular and immune characteristics compared to other causes of HCC and affects both men and women equally. The management of early to intermediate-stage MASH-HCC typically involves surgery and locoregional therapies, while advanced HCC is treated with systemic therapies, including anti-angiogenic therapies and immune checkpoint inhibitors. In this comprehensive review, we consolidate previous research findings while also providing the most current insights into the intricate molecular processes underlying MASH-HCC development. We delve into MASH-HCC-associated genetic variations and somatic mutations, disease progression and research models, multiomics analysis, immunological and microenvironmental impacts, and discuss targeted/combined therapies to overcome immune evasion and the biomarkers to recognize treatment responders. By furthering our comprehension of the molecular mechanisms underlying MASH-HCC, our goal is to catalyze the advancement of more potent treatment strategies, ultimately leading to enhanced patient outcomes.

Shaping Tomorrow's Liver Organoids: A Journey Toward Integrating Bile Ducts

Liver tissue engineering has undergone remarkable developments since the late 20th century, transitioning from simple two-dimensional cultures to sophisticated three-dimensional organoid models for drug toxicity assessments. Stem cell innovations have enabled the creation of liver organoids for disease modelling and tissue engineering. However, a key limitation is the absence of functional bile ducts in these organoids, crucial for replicating bile-duct related diseases. Bile, synthesized by hepatocytes, plays a vital role in digesting fats and expelling lipid-soluble wastes, including drug byproducts. Diseases impeding bile flow are responsible for many liver transplants and can cause severe conditions such as liver cirrhosis, causing over 50,000 annual deaths in the US. Current liver organoids, while bile-producing, are devoid of bile ducts, limiting their efficacy in mimicking diseases related to bile flow. This article underscores the pressing need to incorporate bile ducts in engineered liver tissues, delves into the challenges faced in this effort, and highlights potential solutions through biomaterial and bioengineering techniques. Such advancements will offer researchers enhanced insights into bile duct disorders and pave the way for exploring innovative therapeutic strategies.

Comprehensive analysis of mitophagy-related subtypes of breast cancer and the association with immune related characteristics

Breast cancer (BRCA) is a common neoplasm characterized by high levels of molecular heterogeneity. Previous studies have noted the importance of mitophagy for the progression and prognosis of BRCA. However, little was found in the similarity and difference of mitophagy-related gene expression patterns of BRCA. This study intended to investigate the differences in functional activation, somatic mutation, and immune-related characteristics among different subtypes of BRCA associated with mitophagy. Based on bioinformatics analysis, we systematically examined the heterogeneity of breast cancer concerning mitophagy and observed two distinct subtypes with different tumor microenvironments and prognoses. BRCA samples from TCGA database were divided into two subtypes based on the expression of 29 mitophagy-related genes by ConsensusClusterPlus algorithm. Two mitophagy-related subtypes with marked prognostic discrepancies were significantly correlated with race, intrinsic subtype grouped based on PAM50 subtype purity and BRCA Pathology. The results of GSVA and immune microenvironment analysis showed significant differences in cancer-related and immune-related features between the two subtypes. METABRIC datasets were extracted to validate the immune characteristics scoring and the expression of immune checkpoints between different subtypes based on the medium value of TCGA-Mitophagy score. It is noteworthy that the present study is the first to demonstrate a new classification based on the mitophagy of breast cancer, which comes up with a new perspective for the assessment and prognoses of BRCA.

The oncogenic role of NOTCH1 as biomarker in oral squamous cell carcinoma and oral lichen planus

Background

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer with heterogeneous molecular pathogenesis. Oral lichen planus (OLP) is demonstrated potentially can transfer to OSCC malignant lesions. Unfortunately, there are no definitive prognostic and predictive biomarkers for the clinical management of OSCC patients. The present research is the first study that compared an oral premalignant lesion such as OLP to malignant lesions like OSCC for NOTCH1 expression levels to better understand its oncogenic or tumor suppressive role.

Materials and Methods

In this cross-sectional study, mRNA expression of NOTCH1 was evaluated by quantitative polymerase chain reaction in 65 tissue-embedded Paraffin-Block samples, including 32 OSCC and 33 OLP. Furthermore, we collected demographic information and pathological data, including tumor stage and grade. The association between NOTCH1 and GAPDH gene expressions was determined by Chi-squared, Spearman, and Mann-Whitney tests. A P < 0.05 was considered statistically significant for all statistical analyses.

Results

Comparison of OSCC and OLP groups showed a statistically significant difference between the quantitative expression of the NOTCH1 gene (P < 0.001). Qualitative gene expression was divided into low expression and high expression. Both study groups demonstrated a statistically significant gene expression difference (P < 0.001). There was a statistically significant difference between age and NOTCH1 expression in the OLP group (P = 0.036). There was no correlation between NOTCH1 expression and age, gender, tumor grade, and stage.

Conclusion

Since the OSCC is a malignant lesion and the OLP showed the possible nature of malignancy transformation, we can consider the NOTCH1 as a biomarker for the assessment of the tumorigenesis process with a definition of a standard threshold for potentially malignant lesions and malignant OSCC tumors.

Novel Molecular Subtyping Scheme Based on In Silico Analysis of Cuproptosis Regulator Gene Patterns Optimizes Survival Prediction and Treatment of Hepatocellular Carcinoma

BACKGROUND

The liver plays an important role in maintaining copper homeostasis. Copper ion accumulation was elevated in HCC tissue samples. Copper homeostasis is implicated in cancer cell proliferation and angiogenesis. The potential of copper homeostasis as a new theranostic biomarker for molecular imaging and the targeted therapy of HCC has been demonstrated. Recent studies have reported a novel copper-dependent nonapoptotic form of cell death called cuproptosis, strikingly different from other known forms of cell death. The correlation between cuproptosis and hepatocellular carcinoma (HCC) is not fully understood.

MATERIALS AND METHODS

The transcriptomic data of patients with HCC were retrieved from the Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and were used as a discovery cohort to construct the prognosis model. The gene expression data of patients with HCC retrieved from the International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO) databases were used as the validation cohort. The Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was used to construct the prognosis model. A principal component analysis (PCA) was used to evaluate the overall characteristics of cuproptosis regulator genes and obtain the PC1 and PC2 scores. Unsupervised clustering was performed using the ConsensusClusterPlus R package to identify the molecular subtypes of HCC. Cox regression analysis was performed to identify cuproptosis regulator genes that could predict the prognosis of patients with HCC. The receiver operating characteristics curve and Kaplan-Meier survival analysis were used to understand the role of hub genes in predicting the diagnosis and prognosis of patients, as well as the prognosis risk model. A weighted gene co-expression network analysis (WGCNA) was used for screening the cuproptosis subtype-related hub genes. The functional enrichment analysis was performed using Metascape. The 'glmnet' R package was used to perform the LASSO regression analysis, and the randomForest algorithm was performed using the 'randomForest' R package. The 'pRRophetic' R package was used to estimate the anticancer drug sensitivity based on the data retrieved from the Genomics of Drug Sensitivity in Cancer database. The nomogram was constructed using the 'rms' R package. Pearson's correlation analysis was used to analyze the correlations.

RESULTS

We constructed a six-gene signature prognosis model and a nomogram to predict the prognosis of patients with HCC. The Kaplan-Meier survival analysis revealed that patients with a high-risk score, which was predicted by the six-gene signature model, had poor prognoses (log-rank test p < 0.001; HR = 1.83). The patients with HCC were grouped into three distinct cuproptosis subtypes (Cu-clusters A, B, and C) based on the expression pattern of cuproptosis regulator genes. The patients in Cu-cluster B had poor prognosis (log-rank test p < 0.001), high genomic instability, and were not sensitive to conventional chemotherapeutic treatment compared to the patients in the other subtypes. Cancer cells in Cu-cluster B exhibited a higher degree of the senescence-associated secretory phenotype (SASP), a marker of cellular senescence. Three representative genes, CDCA8, MCM6, and NCAPG2, were identified in patients in Cu-cluster B using WGCNA and the "randomForest" algorithm. A nomogram was constructed to screen patients in the Cu-cluster B subtype based on three genes: CDCA8, MCM6, and NCAPG2.

CONCLUSION

Publicly available databases and various bioinformatics tools were used to study the heterogeneity of cuproptosis in patients with HCC. Three HCC subtypes were identified, with differences in the survival outcomes, genomic instability, senescence environment, and response to anticancer drugs. Further, three cuproptosis-related genes were identified, which could be used to design personalized therapeutic strategies for HCC.

A Novel Notch-Related Gene Signature for Prognosis and Immune Response Prediction in Ovarian Cancer

Background and Objectives: Notch is a fascinating signaling pathway. It is extensively involved in tumor growth, cancer stem cells, metastasis, and treatment resistance and plays important roles in metabolic regulation, tumor microenvironment, and tumor immunity. However, the role of Notch in ovarian cancer (OC) has yet to be fully understood. Therefore, this study systematically described the expression, mutation, and copy number variation of genes in the Notch signaling pathway in OC and evaluated the relationship between gene mutation and Overall Survival (OS) prognosis. Materials and Methods: Notch risk score (NTRS) was established by univariate Cox regression analysis combined with Lasso regression analysis, and the efficacy of NTRS in predicting prognosis and immunotherapy response in patients with OC was verified. We further assessed the correlations of NTRS with clinical features, immune infiltration level, immune checkpoint expression, and immune characteristics. Additionally, differential expression and functions of the fourteen signature genes were confirmed via vitro assays. Results: The results showed that Notch genes (NTGs) were markedly differentiated between tumor and normal tissues, which may help to explain the high heterogeneity in the biological characteristics and therapeutic outcomes of human OC. A Notch risk (NTR) prognostic model based on 11 key NTGs was successfully constructed. Tumors with high Notch risk scores (NTRS) were independently associated with shorter overall survival and poorer immunotherapy outcomes. We further assessed the correlations of NTRS with immune characteristics. The results showed that NTGs play a key role in regulating the tumor immune microenvironment. Additionally, we validated the baseline and induced expressions of 14 prognosis-related NTGs in our own OC samples. In vitro assays confirmed that the knockdown of NCOR2 and APH1B and overexpression of HEY2 and SKP2 could inhibit the proliferation, invasion, and migration of OC cells. Conclusions: These findings emphasize that Notch multilayer changes are associated with the prognosis of patients with OC and the characteristics of immune cell infiltration. Our predictive signature may predict the prognosis and immunotherapy response of OC patients in an independent manner. NCOR2, APH1B, HEY2, and SKP2 may more prominently represent important indicators to improve patient prognosis.

The stromal-tumor amplifying STC1-Notch1 feedforward signal promotes the stemness of hepatocellular carcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs), an important component of the tumor microenvironment (TME), play crucial roles in tumor stemness. It has been shown in various cancer studies that stanniocalcin-1 (STC1) is secreted by CAFs, however, its function in HCC is still not clear.

METHODS

The serum concentration and intracellular expression level of STC1 were quantified by ELISA and western blotting, respectively. The role of CAF-derived STC1 in HCC stemness was investigated by sphere formation, sorafenib resistance, colony formation, and transwell migration and invasion assays in vitro and in an orthotopic liver xenograft model in vivo. An HCC tissue microarray containing 72 samples was used to evaluate the expression of STC1 and Notch1 in HCC tissues. Coimmunoprecipitation (CoIP) and dual-luciferase reporter assays were performed to further explore the underlying mechanisms. ELISAs were used to measure the serum concentration of STC1 in HCC patients.

RESULTS

We demonstrated that CAFs were the main source of STC1 in HCC and that CAF-derived STC1 promoted HCC stemness through activation of the Notch signaling pathway. In HCC patients, the expression of STC1 was positively correlated with Notch1 expression and poor prognosis. The co-IP assay showed that STC1 directly bound to Notch1 receptors to activate the Notch signaling pathway, thereby promoting the stemness of HCC cells. Our data further demonstrated that STC1 was a direct transcriptional target of CSL in HCC cells. Furthermore, ELISA revealed that the serum STC1 concentration was higher in patients with advanced liver cancer than in patients with early liver cancer.

CONCLUSIONS

CAF-derived STC1 promoted HCC stemness via the Notch1 signaling pathway. STC1 might serve as a potential biomarker for the prognostic assessment of HCC, and the stromal-tumor amplifying STC1-Notch1 feedforward signal could constitute an effective therapeutic target for HCC patients.

Myokines: Crosstalk and Consequences on Liver Physiopathology

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease mainly characterized by the hepatic accumulation of lipid inducing a deregulation of β-oxidation. Its advanced form is non-alcoholic steatohepatitis (NASH), which, in addition to lipid accumulation, induces hepatocellular damage, oxidative stress and fibrosis that can progress to cirrhosis and to its final stage: hepatocellular carcinoma (HCC). To date, no specific therapeutic treatment exists. The implications of organ crosstalk have been highlighted in many metabolic disorders, such as diabetes, metabolic-associated liver diseases and obesity. Skeletal muscle, in addition to its role as a reservoir and consumer of energy and carbohydrate metabolism, is involved in this inter-organs’ communication through different secreted products: myokines, exosomes and enzymes, for example. Interestingly, resistance exercise has been shown to have a beneficial impact on different metabolic pathways, such as lipid oxidation in different organs through their secreted products. In this review, we will mainly focus on myokines and their effects on non-alcoholic fatty liver disease, and their complication: non-alcoholic steatohepatitis and HCC.

Disruption of SLFN11 Deficiency-Induced CCL2 Signaling and Macrophage M2 Polarization Potentiates Anti-PD-1 Therapy Efficacy in Hepatocellular Carcinoma

BACKGROUND & AIMS

The therapeutic effect of immune checkpoint inhibitors (ICIs) is poor in hepatocellular carcinoma (HCC) and varies greatly among individuals. Schlafen (SLFN) family members have important functions in immunity and oncology, but their roles in cancer immunobiology remain unclear. We aimed to investigate the role of the SLFN family in immune responses against HCC.

METHODS

Transcriptome analysis was performed in human HCC tissues with or without response to ICIs. A humanized orthotopic HCC mouse model and a co-culture system were constructed, and cytometry by time-of-flight technology was used to explore the function and mechanism of SLFN11 in the immune context of HCC.

RESULTS

SLFN11 was significantly up-regulated in tumors that responded to ICIs. Tumor-specific SLFN11 deficiency increased the infiltration of immunosuppressive macrophages and aggravated HCC progression. HCC cells with SLFN11 knockdown promoted macrophage migration and M2-like polarization in a C-C motif chemokine ligand 2-dependent manner, which in turn elevated their own PD-L1 expression by activating the nuclear factor-κB pathway. Mechanistically, SLFN11 suppressed the Notch pathway and C-C motif chemokine ligand 2 transcription by binding competitively with tripartite motif containing 21 to the RNA recognition motif 2 domain of RBM10, thereby inhibiting tripartite motif containing 21-mediated RBM10 degradation to stabilize RBM10 and promote NUMB exon 9 skipping. Pharmacologic antagonism of C-C motif chemokine receptor 2 potentiated the antitumor effect of anti-PD-1 in humanized mice bearing SLFN11 knockdown tumors. ICIs were more effective in patients with HCC with high serum SLFN11 levels.

CONCLUSIONS

SLFN11 serves as a critical regulator of microenvironmental immune properties and an effective predictive biomarker of ICIs response in HCC. Blockade of C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 signaling sensitized SLFN11^low HCC patients to ICI treatment.

Notch-mediated hepatocyte MCP-1 secretion causes liver fibrosis

Patients with nonalcoholic steatohepatitis (NASH) have increased expression of liver monocyte chemoattractant protein-1 (MCP-1), but its cellular source and contribution to various aspects of NASH pathophysiology remain debated. We demonstrated increased liver CCL2 (which encodes MCP-1) expression in patients with NASH, and commensurately, a 100-fold increase in hepatocyte Ccl2 expression in a mouse model of NASH, accompanied by increased liver monocyte-derived macrophage (MoMF) infiltrate and liver fibrosis. To test repercussions of increased hepatocyte-derived MCP-1, we generated hepatocyte-specific Ccl2-knockout mice, which showed reduced liver MoMF infiltrate as well as decreased liver fibrosis. Forced hepatocyte MCP-1 expression provoked the opposite phenotype in chow-fed wild-type mice. Consistent with increased hepatocyte Notch signaling in NASH, we observed a close correlation between markers of Notch activation and CCL2 expression in patients with NASH. We found that an evolutionarily conserved Notch/recombination signal binding protein for immunoglobulin kappa J region binding site in the Ccl2 promoter mediated transactivation of the Ccl2 promoter in NASH diet-fed mice. Increased liver MoMF infiltrate and liver fibrosis seen in opposite gain-of-function mice was ameliorated with concomitant hepatocyte Ccl2 knockout or CCR2 inhibitor treatment. Hepatocyte Notch activation prompts MCP-1-dependent increase in liver MoMF infiltration and fibrosis.

Treatment of HCC with claudin-1-specific antibodies suppresses carcinogenic signaling and reprograms the tumor microenvironment

BACKGROUND & AIMS

Despite recent approvals, the response to treatment and prognosis of patients with advanced hepatocellular carcinoma (HCC) remain poor. Claudin-1 (CLDN1) is a membrane protein that is expressed at tight junctions, but it can also be exposed non-junctionally, such as on the basolateral membrane of the human hepatocyte. While CLDN1 within tight junctions is well characterized, the role of non-junctional CLDN1 and its role as a therapeutic target in HCC remains unexplored.

METHODS

Using humanized monoclonal antibodies (mAbs) specifically targeting the extracellular loop of human non-junctional CLDN1 and a large series of patient-derived cell-based and animal model systems we aimed to investigate the role of CLDN1 as a therapeutic target for HCC.

RESULTS

Targeting non-junctional CLDN1 markedly suppressed tumor growth and invasion in cell line-based models of HCC and patient-derived 3D ex vivo models. Moreover, the robust effect on tumor growth was confirmed in vivo in a large series of cell line-derived xenograft and patient-derived xenograft mouse models. Mechanistic studies, including single-cell RNA sequencing of multicellular patient HCC tumorspheres, suggested that CLDN1 regulates tumor stemness, metabolism, oncogenic signaling and perturbs the tumor immune microenvironment.

CONCLUSIONS

Our results provide the rationale for targeting CLDN1 in HCC and pave the way for the clinical development of CLDN1-specific mAbs for the treatment of advanced HCC.

IMPACT AND IMPLICATIONS

Hepatocellular carcinoma (HCC) is associated with high mortality and unsatisfactory treatment options. Herein, we identified the cell surface protein Claudin-1 as a treatment target for advanced HCC. Monoclonal antibodies targeting Claudin-1 inhibit tumor growth in patient-derived ex vivo and in vivo models by modulating signaling, cell stemness and the tumor immune microenvironment. Given the differentiated mechanism of action, the identification of Claudin-1 as a novel therapeutic target for HCC provides an opportunity to break the plateau of limited treatment response. The results of this preclinical study pave the way for the clinical development of Claudin-1-specific antibodies for the treatment of advanced HCC. It is therefore of key impact for physicians, scientists and drug developers in the field of liver cancer and gastrointestinal oncology.

Multiomics Integration at Single-Cell Resolution Using Bayesian Networks: A Case Study in Hepatocellular Carcinoma

Multiomics data integration is one of the leading frontiers of complex disease research and integrative biology. The advances in single-cell sequencing technologies offer yet another crucial dimension in multiomics research. The single-cell studies enable the study and integration of multiomics data simultaneously in the same cell. We report in this study multiomics data integration in single-cell resolution using Bayesian networks (BNs) in a case study of hepatocellular carcinoma (HCC). A BN encodes the conditional dependencies/independencies of variables using a graphical model with an accompanying joint probability. RNA-seq and Reduced Representation Bisulfite Sequencing data were analyzed separately, and copy number variations were estimated by the hidden Markov model method. Several BN models were constructed to reveal omics' causal and associational relationships. These methods were subjected to a validation study using an independent data set. We show the heterogeneity of the multiple cellular layers of HCC at single-cell omics resolution by identifying best-fitted BN models of 295 genes. We also provide novel insights into the multiomics mechanistic relationships in the human lymphocyte antigen class I genes in HCC. To the best of our knowledge, this is the first study to focus on integrating omics data using a machine learning algorithm, BNs, at the single-cell resolution using a case study of HCC.

Tumorigenesis from non-alcoholic steatohepatitis to hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) with metabolic syndrome is increasing to be a main cause of hepatocellular carcinoma (HCC). However, the mechanism of tumorigenesis in NASH induced HCC is still not clear. In this perspective, we will discuss the recent progress that has been made to understand the genetic change and the immune microenvironment of HCC, and the remaining questions. Based on the current study, NASH-HCC is likely to have novel mechanism, which needs more investigation in future.

Comprehensive analysis of m5C-Related lncRNAs in the prognosis and immune landscape of hepatocellular carcinoma

5-Methyladenosine (m5C) is a type of epigenetic modification involved in the progression of various cancers. To investigate the role of m5C-related long non-coding RNAs (lncRNAs) in the prognosis and immune cell infiltration in hepatocellular carcinoma (HCC), we obtained patients' clinical information and transcriptome data of HCC from the Cancer Genome Atlas (TCGA) database. We applied Pearson correlation analysis to construct an m5C-related lncRNA-messenger RNA (mRNA) co-expression network. Univariate Cox analysis, least absolute shrinkage and selection operator (LASSO), and multivariate Cox analysis were employed to establish an m5C-related lncRNA prognostic risk model. We then verified the model using Kaplan-Meier analysis, principal component analysis, as well as univariate and multivariate Cox analyses. The expression of m5C-related lncRNAs was validated in HCC tissues and different cell lines. Combining the risk score and clinicopathological features, a nomogram was established for predicting the overall survival (OS) of HCC patients. Furthermore, gene set enrichment analysis (GSEA) revealed that some tumor-associated pathways were significantly enriched in the high-risk group. Immune cell infiltration analysis demonstrated that the levels of Treg cells, neutrophils, and M2 macrophages were higher in the high-risk group. In addition, patients with high tumor mutation burden (TMB) had worse OS than those with low TMB. We also assessed the immune checkpoint level and chemotherapeutic agent sensibility. Then in vitro experiments were performed to examine the biological function of MKLN1-AS in HCC cells and found that knockdown of MKLN1-AS suppressed the proliferation, migration, and invasion. In conclusion, m5C-related lncRNAs played a critical role in predicting the prognosis of patients with HCC and may serve as new therapeutic targets for HCC patients.

mTOR: A Potential New Target in Nonalcoholic Fatty Liver Disease

The global prevalence of nonalcoholic fatty liver disease (NAFLD) continues to rise, yet effective treatments are lacking due to the complex pathogenesis of this disease. Although recent research has provided evidence for the “multiple strikes” theory, the classic “two strikes” theory has not been overturned. Therefore, there is a crucial need to identify multiple targets in NAFLD pathogenesis for the development of diagnostic markers and targeted therapeutics. Since its discovery, the mechanistic target of rapamycin (mTOR) has been recognized as the central node of a network that regulates cell growth and development and is closely related to liver lipid metabolism and other processes. This paper will explore the mechanisms by which mTOR regulates lipid metabolism (SREBPs), insulin resistance (Foxo1, Lipin1), oxidative stress (PIG3, p53, JNK), intestinal microbiota (TLRs), autophagy, inflammation, genetic polymorphisms, and epigenetics in NAFLD. The specific influence of mTOR on NAFLD was hypothesized to be divided into micro regulation (the mechanism of mTOR’s influence on NAFLD factors) and macro mediation (the relationship between various influencing factors) to summarize the influence of mTOR on the developmental process of NAFLD, and prove the importance of mTOR as an influencing factor of NAFLD regarding multiple aspects. The effects of crosstalk between mTOR and its upstream regulators, Notch, Hedgehog, and Hippo, on the occurrence and development of NAFLD-associated hepatocellular carcinoma are also summarized. This analysis will hopefully support the development of diagnostic markers and new therapeutic targets in NAFLD.

Role of miRNAs in Human T Cell Leukemia Virus Type 1 Induced T Cell Leukemia: A Literature Review and Bioinformatics Approach

Human T cell leukemia virus type 1 (HTLV-1) was identified as the first pathogenic human retrovirus and is estimated to infect 5 to 10 million individuals worldwide. Unlike other retroviruses, there is no effective therapy to prevent the onset of the most alarming diseases caused by HTLV-1, and the more severe cases manifest as the malignant phenotype of adult T cell leukemia (ATL). MicroRNA (miRNA) dysfunction is a common feature of leukemogenesis, and it is no different in ATL cases. Therefore, we sought to analyze studies that reported deregulated miRNA expression in HTLV-1 infected cells and patients’ samples to understand how this deregulation could induce malignancy. Through in silico analysis, we identified 12 miRNAs that stood out in the prediction of targets, and we performed functional annotation of the genes linked to these 12 miRNAs that appeared to have a major biological interaction. A total of 90 genes were enriched in 14 KEGG pathways with significant values, including TP53, WNT, MAPK, TGF-β, and Ras signaling pathways. These miRNAs and gene interactions are discussed in further detail for elucidation of how they may act as probable drivers for ATL onset, and while our data provide solid starting points for comprehension of miRNAs’ roles in HTLV-1 infection, continuous effort in oncologic research is still needed to improve our understanding of HTLV-1 induced leukemia.

Notch–Sox9 Axis Mediates Hepatocyte Dedifferentiation in KrasG12V-Induced Zebrafish Hepatocellular Carcinoma

Liver cancer is one of the most prevalent cancers in humans. Hepatocytes normally undergo dedifferentiation after the onset of hepatocellular carcinoma, which in turn facilitates the progression of cancer. Although the process of hepatocellular carcinoma dedifferentiation is of significant research and clinical value, the cellular and molecular mechanisms underlying it are still not fully characterized. We constructed a zebrafish liver cancer model based on overexpression of the oncogene krasG12V to investigate the hepatocyte dedifferentiation in hepatocellular carcinoma. We found that, after hepatocarcinogenesis, hepatocytes dedifferentiated and the Notch signaling pathway was upregulated in this progress. Furthermore, we found that inhibition of the Notch signaling pathway or deficiency of sox9b both prevented hepatocyte dedifferentiation following hepatocellular carcinoma induction, reducing cancer metastasis and improving survival. In conclusion, we found that hepatocytes undergo dedifferentiation after hepatocarcinogenesis, a process that requires Notch signaling and likewise the activation of Sox9.

ADAM12 is an independent predictor of poor prognosis in liver cancer

Disintegrin and metalloproteinase 12 (ADAM12) is thought to trigger the occurrence and development of numerous tumours, including colorectal, breast, and pancreatic cancers. On the basis of The Cancer Genome Atlas (TCGA) datasets, in this study, the relationship between ADAM12 gene expression and hepatocellular carcinoma (HCC), the prognostic value of this relationship, and the potential mechanisms influencing HCC development were evaluated. The results showed that the ADAM12 gene was significantly and highly expressed in liver cancer tissue. The high expression of the ADAM12 gene in liver cancer tissue significantly and positively correlated with T stage, pathological stage, and residual tumour. Kaplan–Meier and Cox regression analyses revealed that ADAM12 gene expression is an independent risk factor influencing the prognosis of patients with liver cancer. Pathway analyses of ADAM12 in HCC revealed ADAM12-correlated signalling pathways, and the expression level of ADAM12 was associated with immune cell infiltration. In vitro experiments demonstrated that the expression level of ADAM12 in Huh-7 and Hep3B cells was significantly higher than that in other HCC cells. ShRNA transfection experiments confirmed that the expression levels of TGF-β and Notch pathway-related proteins were significantly decreased. An EdU cell proliferation assay showed that a low level of ADAM12 gene expression significantly inhibited the proliferative activity of HCC cells. Cell cycle experiments showed that low ADAM12 expression blocked the G1/S phase transition. Overall, this research revealed that high ADAM12 gene expression implies a poor prognosis for patients with primary liver cancer. In addition, it is a potential indicator for the diagnosis of liver cancer.

TAZ-induced Cybb contributes to liver tumor formation in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Non-alcoholic steatohepatitis (NASH) is a leading cause of hepatocellular carcinoma (HCC), but mechanisms linking NASH to eventual tumor formation remain poorly understood. Herein, we investigate the role of TAZ/WWTR1, which is induced in hepatocytes in NASH, in the progression of NASH to HCC.

METHODS

The roles of hepatocyte TAZ and its downstream targets were investigated in diet-induced and genetic models of NASH-HCC using gene-targeting, adeno-associated virus 8 (AAV8)-H1-mediated gene silencing, or AAV8-TBG-mediated gene expression. The biochemical signature of the newly elucidated pathway was probed in liver specimens from humans with NASH-HCC.

RESULTS

When hepatocyte-TAZ was silenced in mice with pre-tumor NASH using AAV8-H1-shTaz (short-hairpin Taz), subsequent HCC tumor development was suppressed. In this setting, the tumor-suppressing effect of shTaz was not dependent of TAZ silencing in the tumors themselves and could be dissociated from the NASH-suppressing effects of shTaz. The mechanism linking pre-tumor hepatocyte-TAZ to eventual tumor formation involved TAZ-mediated induction of the NOX2-encoding gene Cybb, which led to NADPH-mediated oxidative DNA damage. As evidence, DNA damage and tumor formation could be suppressed by treatment of pre-tumor NASH mice with AAV8-H1-shCybb; AAV8-TBG-OGG1, encoding the oxidative DNA-repair enzyme 8-oxoguanine glycosylase; or AAV8-TBG-NHEJ1, encoding the dsDNA repair enzyme non-homologous end-joining factor 1. In surrounding non-tumor tissue from human NASH-HCC livers, there were strong correlations between TAZ, NOX2, and oxidative DNA damage.

CONCLUSIONS

TAZ in pre-tumor NASH-hepatocytes, via induction of Cybb and NOX2-mediated DNA damage, contributes to subsequent HCC tumor development. These findings illustrate how NASH provides a unique window into the early molecular events that can lead to tumor formation and suggest that NASH therapies targeting TAZ might also prevent NASH-HCC.

LAY SUMMARY

Non-alcoholic steatohepatitis (NASH) is emerging as the leading cause of a type of liver cancer called hepatocellular carcinoma (HCC), but molecular events in pre-tumor NASH hepatocytes leading to HCC remain largely unknown. Our study shows that a protein called TAZ in pre-tumor NASH-hepatocytes promotes damage to the DNA of hepatocytes and thereby contributes to eventual HCC. This study reveals a very early event in HCC that is induced in pre-tumor NASH, and the findings suggest that NASH therapies targeting TAZ might also prevent NASH-HCC.

Notch signaling pathway: architecture, disease, and therapeutics

The NOTCH gene was identified approximately 110 years ago. Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway. NOTCH receptors undergo three cleavages and translocate into the nucleus to regulate the transcription of target genes. NOTCH signaling deeply participates in the development and homeostasis of multiple tissues and organs, the aberration of which results in cancerous and noncancerous diseases. However, recent studies indicate that the outcomes of NOTCH signaling are changeable and highly dependent on context. In terms of cancers, NOTCH signaling can both promote and inhibit tumor development in various types of cancer. The overall performance of NOTCH-targeted therapies in clinical trials has failed to meet expectations. Additionally, NOTCH mutation has been proposed as a predictive biomarker for immune checkpoint blockade therapy in many cancers. Collectively, the NOTCH pathway needs to be integrally assessed with new perspectives to inspire discoveries and applications. In this review, we focus on both classical and the latest findings related to NOTCH signaling to illustrate the history, architecture, regulatory mechanisms, contributions to physiological development, related diseases, and therapeutic applications of the NOTCH pathway. The contributions of NOTCH signaling to the tumor immune microenvironment and cancer immunotherapy are also highlighted. We hope this review will help not only beginners but also experts to systematically and thoroughly understand the NOTCH signaling pathway.

Oxidative Stress in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it still remains an orphan of adequate therapies. This review highlights the interaction between oxidative stress (OS) and disturbed lipid metabolism. Several reactive oxygen species generators, including those produced in the gastrointestinal tract, contribute to the lipotoxic hepatic (and extrahepatic) damage by fatty acids and a great variety of their biologically active metabolites in a “multiple parallel-hit model”. This leads to inflammation and fibrogenesis and contributes to NAFLD progression. The alterations of the oxidant/antioxidant balance affect also metabolism-related organelles, leading to lipid peroxidation, mitochondrial dysfunction, and endoplasmic reticulum stress. This OS-induced damage is at least partially counteracted by the physiological antioxidant response. Therefore, modulation of this defense system emerges as an interesting target to prevent NAFLD development and progression. For instance, probiotics, prebiotics, diet, and fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. The OS and its counter-regulation are under the influence of individual genetic and epigenetic factors as well. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors, coupled with new OS biomarkers, will likely assist in noninvasive diagnosis and monitoring of NAFLD progression and in further personalizing treatments.

Histone Acetylation Regulator-Mediated Acetylation Patterns Define Tumor Malignant Pathways and Tumor Microenvironment in Hepatocellular Carcinoma

Background

Histone acetylation modification is one of the most common epigenetic methods used to regulate chromatin structure, DNA repair, and gene expression. Existing research has focused on the importance of histone acetylation in regulating tumorigenicity, tumor progression, and tumor microenvironment (TME) but has not explored the potential roles and interactions of histone acetylation regulators in TME cell infiltration, drug sensitivity, and immunotherapy.

Methods

The mRNA expression and genetic alterations of 36 histone acetylation regulators were analyzed in 1599 hepatocellular carcinoma (HCC) samples. The unsupervised clustering method was used to identify the histone acetylation patterns. Then, based on their differentially expressed genes (DEGs), an HAscore model was constructed to quantify the histone acetylation patterns and related subtypes of individual samples. Lastly, the relationship between HAscore and transcription background, tumor clinical features, characteristics of TME, drug response, and efficacy of immunotherapy were analyzed.

Results

We identified three histone acetylation patterns characterized by high, medium, and low HAscore. Patients with HCC in the high HAscore group experienced worse overall survival time, and the cancer-related malignant pathways were more active in the high HAscore group, comparing to the low HAscore group. The high HAscore group was characterized by an immunosuppressive subtype because of the high infiltration of immunosuppressive cells, such as regulatory T cells and myeloid-derived suppressor cells. Following validation, the HAscore was highly correlated with the sensitivity of anti-tumor drugs; 116 therapeutic agents were found to be associated with it. The HAscore was also correlated with the therapeutic efficacy of the PD-L1 and PD-1 blockade, and the response ratio was significantly higher in the low HAscore group.

Conclusion

To the best of our knowledge, our study is the first to provide a comprehensive analysis of 36 histone acetylation regulators in HCC. We found close correlations between histone acetylation patterns and tumor malignant pathways and TME. We also analyzed the therapeutic value of the HAscore in targeted therapy and immunotherapy. This work highlights the interactions and potential clinical utility of histone acetylation regulators in treatment of HCC and improving patient outcomes.

Two distinct Notch signals, Delta-like 4/Notch1 and Jagged-1/Notch2, antagonistically regulate chemical hepatocarcinogenesis in mice

Notch signaling is one of the most common drivers of carcinogenesis in many types of cancers, including hepatocellular carcinoma (HCC); however, it occasionally suppresses tumor progression. Moreover, it is virtually unknown how different sets of Notch ligands and receptors regulate the HCC development. In this study, we demonstrate that the expression of the Notch ligands, Delta-like 4 (Dll4) and Jagged-1 (Jag1), is upregulated during diethylnitrosamine-induced hepatocarcinogenesis. Dll4 is detected in the preneoplastic hepatocytes and HCC cells, but not in the normal hepatocytes, while Jag1 is expressed in the desmin-positive mesenchymal cells. Hepatocyte-specific Dll4 knockout abolishes the Notch1 signaling and suppresses the tumor progression. In contrast, Jag1 deletion induces the ectopic expression of Dll4 in hepatocytes along with the loss of Notch2 signaling, leading to the tumor progression. These results indicate that the two distinct Notch signals, Dll4/Notch1 and Jag1/Notch2, are antagonistic to each other, exerting opposite effects on HCC progression.

Dll4/Notch1 signal promotes the progression of HCC, while Jag1/Notch2 signal antagonistically suppresses it in murine chemical hepatocarcinogenesis. Nakano et al. report that two distinct Notch signals regulate the progression of hepatocellular carcinoma (HCC) using tissue specific loss of function mouse mutants. They find Dll4/Notch1 signal promotes HCC progression, while the Jag1/Notch2 signal antagonistically suppresses it.

EMT and Inflammation: Crossroads in HCC

Hepatocellular carcinoma is one of the major causes of cancer-related deaths worldwide and is associated with several inflammatory mediators, since 90% of HCCs occur based on chronic hepatitis B or C, alcoholism or increasingly metabolic syndrome-associated inflammation. EMT is a physiological process, with coordinated changes in epithelial gene signatures and is regulated by multiple factors, including cytokines and growth factors such as TGFβ, EGF, and FGF. Recent reports propose a strong association between EMT and inflammation, which is also correlated with tumor aggressiveness and poor outcomes. Cellular heterogeneity results collectively as an outcome of EMT, inflammation, and the tumor microenvironment, and it plays a fundamental role in the progression, complexity of cancer, and chemoresistance. In this review, we highlight recent developments concerning the association of EMT and inflammation in the context of HCC progression. Identifying potential EMT-related biomarkers and understanding EMT regulatory molecules will likely contribute to promising developments in clinical practice and will be a valuable tool for predicting metastasis in general and specifically in HCC.

The Role of Notch Signaling Pathway in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, and progressive NAFLD can develop into non-alcoholic steatohepatitis (NASH), liver cirrhosis, or hepatocellular carcinoma (HCC). NAFLD is a kind of metabolic disordered disease, which is commonly associated with lipid metabolism, insulin resistance, oxidative stress, inflammation, and fibrogenesis, as well as autophagy. Growing studies have shown Notch signaling pathway plays a pivotal role in the regulation of NAFLD progression. Here, we review the profile of the Notch signaling pathway, new evidence of Notch signaling involvement in NAFLD, and describe the potential of Notch as a biomarker and therapeutic target for NAFLD treatment.

Molecular subclassification of gastrointestinal cancers based on cancer stem cell traits

Human gastrointestinal malignancies are highly heterogeneous cancers. Clinically, heterogeneity largely contributes to tumor progression and resistance to therapy. Heterogeneity within gastrointestinal cancers is defined by molecular subtypes in genomic and transcriptomic analyses. Cancer stem cells (CSCs) have been demonstrated to be a major source of tumor heterogeneity; therefore, assessing tumor heterogeneity by CSC trait-guided classification of gastrointestinal cancers is essential for the development of effective therapies. CSCs share critical features with embryonic stem cells (ESCs). Molecular investigations have revealed that embryonic genes and developmental signaling pathways regulating the properties of ESCs or cell lineage differentiation are abnormally active and might be oncofetal drivers in certain tumor subtypes. Currently, multiple strategies allow comprehensive identification of tumor subtype-specific oncofetal signatures and evaluation of subtype-specific therapies. In this review, we summarize current knowledge concerning the molecular classification of gastrointestinal malignancies based on CSC features and elucidate their clinical relevance. We also outline strategies for molecular subtype identification and subtype-based therapies. Finally, we explore how clinical implementation of tumor classification by CSC subtype might facilitate the development of more effective personalized therapies for gastrointestinal cancers.

Zonation in NASH - A key paradigm for understanding pathophysiology and clinical outcomes

Non-alcoholic fatty liver disease (NAFLD) exists as a spectrum ranging from simple steatosis to histologically defined hepatocyte injury and inflammatory changes that define steatohepatitis (NASH), and increase risk for fibrosis. Although zonal differences in NASH have not been systematically studied, periportal involvement has been associated with worse metabolic outcomes and more hepatic fibrosis as compared to pericentral disease. These data suggest that hepatic zonation of disease may influence the diversity of clinical presentations. Similarly, several randomized clinical trials suggest a differential response based on zonation of disease, with preferential effects on periportal (cysteamine) or pericentral disease (obeticholic acid, pioglitazone). Intriguingly, morphogenic pathways known to affect zonal development and maintenance - WNT/β-Catenin, Hedgehog, HIPPO/Yap/TAZ and Notch - have been implicated in NASH pathogenesis, and nuclear hormone receptors downstream of potential NASH therapeutics show zonal preferences. In this review, we summarize these data and propose that patient-specific activation of these pathways may explain the variability in clinical presentation, and the zone-specific response observed in clinical trials.

Notch2 suppresses the development of allergic rhinitis by promoting FOXP3 expression and Treg cell differentiation

AIMS

Notch signaling is closely related to a variety of diseases, but the role of Notch2 in allergic rhinitis (AR) remain unclear. This study was performed to investigate the effects of Notch2 on the differentiation of Treg cells and on the inflammatory response of AR.

MATERIALS AND METHODS

Peripheral blood (including 101 AR patients and 66 Controls) and nasal mucosa (including 19 AR patients and 17 Controls) were collected to detect the expression levels of Notch2, NICD2 and FOXP3. CD4+ T cells of human origin were selected to detect the effects of Notch2 on the differentiation of Treg cells and FOXP3. An AR mouse model was established, and lentiviruses overexpressing Notch2 were administered. Then, allergic symptoms, OVA-sIgE titers, nasal mucosal inflammation, Th1/Th2/Th17 cytokines and splenic Treg cells were assessed.

KEY FINDINGS

Compared with that in the Control group, the expression of Notch2 in the AR group was decreased, and Notch2 expression was negatively correlated with the degree of allergy (P < 0.01). The expression levels of Notch2, NICD2 and FOXP3 were decreased in the nasal mucosa of AR patients. Notch2 can promote the differentiation of human Treg cells in vitro (P < 0.05), and Notch2 can directly promote FOXP3 transcription. Animal experiments showed after the upregulation of Notch2 expression, the allergic inflammatory of mice with AR was reduced, the differentiation of Treg cells was increased, and the imbalance of T cells was reversed (P < 0.05).

SIGNIFICANCE

Notch2 promotes the differentiation of Treg cells by upregulating FOXP3 expression, thus significantly inhibiting the inflammatory response of AR.

Extra- and Intra-Cellular Mechanisms of Hepatic Stellate Cell Activation

Hepatic fibrosis is characterized by the pathological accumulation of extracellular matrix (ECM) in the liver resulting from the persistent liver injury and wound-healing reaction induced by various insults. Although hepatic fibrosis is considered reversible after eliminating the cause of injury, chronic injury left unchecked can progress to cirrhosis and liver cancer. A better understanding of the cellular and molecular mechanisms controlling the fibrotic response is needed to develop novel clinical strategies. It is well documented that activated hepatic stellate cells (HSCs) is the most principal cellular players promoting synthesis and deposition of ECM components. In the current review, we discuss pathways of HSC activation, emphasizing emerging extra- and intra-cellular signals that drive this important cellular response to hepatic fibrosis. A number of cell types and external stimuli converge upon HSCs to promote their activation, including hepatocytes, liver sinusoidal endothelial cells, macrophages, cytokines, altered ECM, hepatitis viral infection, enteric dysbiosis, lipid metabolism disorder, exosomes, microRNAs, alcohol, drugs and parasites. We also discuss the emerging signaling pathways and intracellular events that individually or synergistically drive HSC activation, including TGFβ/Smad, Notch, Wnt/β-catenin, Hedgehog and Hippo signaling pathways. These findings will provide novel potential therapeutic targets to arrest or reverse fibrosis and cirrhosis.

Prognostic Cancer Gene Expression Signatures: Current Status and Challenges

Current staging systems of cancer are mainly based on the anatomical extent of disease. They need refinement by biological parameters to improve stratification of patients for tumor therapy or surveillance strategies. Thanks to developments in genomic, transcriptomic, and big-data technologies, we are now able to explore molecular characteristics of tumors in detail and determine their clinical relevance. This has led to numerous prognostic and predictive gene expression signatures that have the potential to establish a classification of tumor subgroups by biological determinants. However, only a few gene signatures have reached the stage of clinical implementation so far. In this review article, we summarize the current status, and present and future challenges of prognostic gene signatures in three relevant cancer entities: breast cancer, colorectal cancer, and hepatocellular carcinoma.