TLR4 signaling promotes a COX-2/PGE2/STAT3 positive feedback loop in hepatocellular carcinoma (HCC) cells

Oleander attenuates hepatic inflammation in a TLR4-independent manner and by favorable modulation of hepatocellular global metabolome that supports cytoprotection

ETHNOPHARMACOLOGICAL RELEVANCE

Nerium oleander is used to treat liver-associated chronic metabolic diseases in traditional medicinal systems across the globe. The hepatoprotective effects of oleander are mentioned in Indian and Chinese traditional medicinal literature.

AIM OF THE STUDY

The present study aimed to investigate the cellular mechanisms behind the hepatoprotective effects of a non-toxic dose of oleander (NO).

MATERIALS AND METHODS

The hepatoprotective effects of NO were tested against lipopolysaccharide (LPS)-treated HepG2 cells. Oxidative stress response was studied using cellular enzymatic assays, and gene expression was analyzed using qRT-PCR. HepG2 cells were pretreated with TAK-242 (pharmacological inhibitor of TLR4) to decipher the anti-inflammatory mechanisms of NO. Cell-free metabolites were analyzed using GCMS and were subjected to pathway enrichment analysis.

RESULTS

NO reduced systemic inflammation, serum lipid peroxidation byproducts, and glucose without affecting serum transaminase levels and hepatic histopathological features. NO attenuated the inflammation-induced loss of antioxidant enzyme activities and mRNA expressions of toll-like receptor-4 (TLR4)/nuclear factor κβ (NFκβ)-dependent inflammatory genes. In TAK-242 pretreated cells, LPS was unable to induce inflammatory and oxidative responses. However, NO treatment in TAK-242 pretreated cells with LPS stimulation further reduced the signs of inflammation and improved hepatoprotective activities. A comparative analysis of the intracellular global metabolome from HepG2 cells with and without NO treatment indicated NO-mediated favorable modulation of intracellular metabolic pathways that support cytoprotective activities.

CONCLUSION

NO protects HepG2 cells from LPS-induced oxidative and inflammatory injury. The hepatoprotective effects of NO are mediated by a TLR4-independent process and through a favorable modulation of the intracellular global metabolome that supports cytoprotection.

Effect of Transarterial Chemotherapy on the Structure and Function of Gut Microbiota in New Zealand White Rabbits

The gut microbiota (GM) are closely related to hepatocellular carcinoma (HCC) occurrence and development. Furthermore, patients with HCC who have received transcatheter arterial chemoembolization (TACE) treatment often experience adverse gastrointestinal reactions, which may be related to changes in the GM caused by the chemotherapeutic drugs used in TACE. Therefore, we conducted animal experiments to investigate these changes. We analyzed changes in the GM of New Zealand white rabbits treated with hepatic arterial chemotherapy by measuring the levels of serological and colonic tissue markers. Simultaneously, we evaluated the correlation between the GM and these markers to explore the mechanism by which chemotherapy affects the GM. Following transarterial chemotherapy with epirubicin, the Firmicutes abundance decreased, whereas that of Proteobacteria increased. The relative abundance of beneficial bacteria, such as Muribaculaceae, Enterococcus, Ruminococcus, and Clostridia, decreased in the experimental group compared with those in the control group. However, the relative abundance of harmful bacteria, such as Bacteroides and Escherichia (Shigella), was higher in the experimental group than in the control group. Following chemotherapy, the GM of rabbits showed a dynamic change over time, first aggravating and then subsiding. The changes were most notable on the fourth day after surgery and recovered slightly on the seventh day. The changes in the host's GM before and after arterial chemotherapy are evident. Hepatic arterial chemotherapy induces dysbiosis of the intestinal microbiota, disrupts intestinal barrier function, damages the integrity of the intestinal mucosa, increases intestinal permeability, facilitates excessive passage of harmful substances through the gut-liver axis communication between the liver and intestine, and triggers activation of inflammatory pathways such as LPS-TLR-4-pSTAT3, ultimately leading to an inflammatory response. This study provides a theoretical basis for combining TACE with targeted GM intervention to treat HCC and reduce adverse gastrointestinal reactions.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Anti-lung Cancer Activity of Synthesized Substituted 1,4-Benzothiazines: An Insight from Molecular Docking and Experimental Studies

BACKGROUND

Thiazine, a 6-membered distinctive heterocyclic motif with sulfur and nitrogen atoms, is one of the heterocyclic compounds that functions as a core scaffold in a number of medicinally significant molecules. Small thiazine-based compounds may operate simultaneously on numerous therapeutic targets and by employing a variety of methods to halt the development, proliferation, and vasculature of cancer cells. We have, herein, reported a series of substituted 1,4 benzothiazines as potential anticancer agents for the treatment of lung cancer.

METHODS

In order to synthesize 2,3-disubstituted-1,4 benzothiazines in good yield, a facile green approach for the oxidative cycloaddition of 2-amino benzenethiol and 1,3-dicarbonyls employing a catalytic amount of ceric ammonium nitrate has been devised. All the molecules have been characterized by spectral analysis and tested for anticancer activity against the A-549 lung cancer cell line using various functional assays. Further in silico screening of compound 3c against six crucial inflammatory molecular targets, such as Il1-α (PDB ID: 5UC6), Il1- β (PDB ID: 6Y8I), Il6 (PDB ID: 1P9M), vimentin (PDB ID: 3TRT), COX-2 (PDB ID: 5KIR), Il8 (PDB ID: 5D14), and TNF-α (PDB ID: 2AZ5), was done using AutoDock tool.

RESULTS

Among the synthesized compounds, propyl 3-methyl-3,4-dihydro-2H-benzo[b][1,4]thiazine-2- carboxylate (3c) was found to be most active based on cell viability assays using A-549 lung cancer cell line and was found to effectively downregulate various pro-inflammatory genes, like Il1-α, Il1-β, Il6, vimentin, COX-2, Il8, and TNF-α in vitro. The ability of the molecule to effectively suppress the proliferation and migration of lung cancer cells in vitro has been further demonstrated by the colony formation unit assay and wound healing assay. Molecular docking analysis showed the maximal binding affinity (- 7.54 kcal/mol) to be exhibited by compound 3c against IL8.

CONCLUSION

A green unconventional route for the synthesis of 2,3-disubstituted-1,4 benzothiazines has been developed. All the molecules were screened for their activity against lung cancer and the data suggested that the presence of an additional unbranched alkyl group attached to the thiazine ring increased their activity. Also, in vitro and in silico modeling confirmed the anti-cancer efficiency of compound 3c, encouraging the exploration of such small molecules against cancer.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

RPLP2 activates TLR4 in an autocrine manner and promotes HIF-1α-induced metabolic reprogramming in hepatocellular carcinoma

Metabolic reprogramming is a major feature of cancer, and aerobic glycolysis is one of the most widely studied metabolic reprogramming processes. Acidic ribosome protein P2 (RPLP2) is associated with both tumorigenesis and endoplasmic reticulum stress. However, limited knowledge exists regarding the role of RPLP2 in hepatocellular carcinoma (HCC) progression. In the present study, we observed a significant upregulation of RPLP2 in HCC tissues. Moreover, RPLP2 expression is closely correlated with patient prognosis and survival. The subsequent experimental validation demonstrated that RPLP2 exerted a regulatory effect on the expression of glycolytic enzymes and lactate production, thereby facilitating HCC cell proliferation. Mechanistically, the PI3K/AKT signalling pathway was found to play an important role in the regulation of hypoxia-inducible factor-1α (HIF-1α)-mediated aerobic glycolysis and cell growth. RPLP2 activates TLR4 on the surface of HCC cells and the downstream PI3K/AKT pathway through autocrine signalling. This activation then facilitates the entry of HIF-1α into the nucleus, enabling it to fulfil its transcriptional function. In conclusion, our findings suggested that RPLP2 induces a metabolic shift towards aerobic glycolysis and facilitates the progression of HCC through TLR4-dependent activation of the PI3K/AKT/HIF-1α pathway. Our study revealed the novel mechanism by which the ribosomal protein RPLP2 regulates glycolysis to promote HCC progression. These findings may offer a potential therapeutic target for HCC treatment.

Protective effects of Althaea officinalis L. extract against N-diethylnitrosamine-induced hepatocellular carcinoma in male Wistar rats through antioxidative, anti-inflammatory, mitochondrial apoptosis and PI3K/Akt/mTOR signaling pathways

Hepatocellular carcinoma is the fourth cause of death due to cancer and includes 90% of liver tumors. Therefore, in this study, it was tried to show that Althaea officinalis L. flower extract (ALOF) can protect hepatocytes against N-diethylnitrosamine (DEN)-induced hepatocellular carcinoma. Totally, 70 Wistar rats were divided into seven groups (n = 10/group) of sham, DEN, treatment with silymarin (SIL; DEN + SIL), treatment with ALOF (DEN + 250 and 500 ALOF), and cotreatment with SIL and ALOF (DEN + SIL + 250 and 500 ALOF). At the end of the study, the serum levels of liver indices (albumin, total protein, bilirubin, C-reactive protein, ALT, AST, and ALP), inflammatory cytokines (IL-6, IL-1β, IL-10, and TNF-α), and oxidants parameters (glutathione peroxidase [GPx], superoxide dismutase [SOD], catalase [CAT] activity along with nitric oxide [NO] levels) were evaluated. The level of Bax, Bcl-2, Caspase-3, p53, PI3K, mTOR, and AKT genes were measured. ALOF in cotreatment with SIL was able to regulate liver biochemical parameters, improve serum antioxidant indices, and decrease the level of proinflammatory cytokines significantly (p < .05). ALOF extract in both doses of 250 and 500 mg/kg in cotreatment with SIL caused a significant (p < .05) decrease in the p53-positive cells and a significant (p < .05) increase in Bcl-2-positive cells. Therefore, ALOF was able to modulate the proliferation of cancer cells and protect normal cells through the regulation of Bax/Bcl-2/p53 and PI3K/Akt/mTOR signaling pathways. It seems that ALOF can be used as a prodrug or complementary treatment in the protection of hepatocytes in induced damages caused by carcinogens.

Targeting Store-Operated Calcium Entry Regulates the Inflammation-Induced Proliferation and Migration of Breast Cancer Cells

Persistent challenges complicating the treatment of breast cancer remain, despite some recent undeniable successes. Sufficient evidence currently exists demonstrating the crucial role of inflammation, characterized by the enhanced activation of Toll-like receptor 4 (TLR4) and the COX-2/PGE2 pathway, in the migration and proliferation of breast cancer cells. Interestingly, the store-operated calcium entry (SOCE) pathway was shown to be essential for the TLR4 activity and COX-2 expression in immune cells such as macrophages and microglia. However, whether SOCE influences inflammatory signaling and the inflammation-induced proliferation and migration of breast cancer cells is still unknown. Thus, the current study intended to delineate the role of SOCE in the TLR4-induced inflammation, migration, and proliferation of breast cancer cells. To this end, MDA-MB-231 breast cancer cells were treated with lipopolysaccharide (LPS) to activate TLR4, BTP2 to inhibit SOCE, and Thapsigargin to induce SOCE. Following these treatments, several experiments were conducted to evaluate the proliferation and migration rates of the MDA-MB-231 cells and the expression of several inflammatory and oncogenic genes, including COX-2, PGE2, IL-6, IL-8, and VEGF. Different techniques were used to achieve the aims of this study, including qRT-PCR, Western blotting, ELISA, MTT, and wound healing assays. This study shows that SOCE inhibition using BTP2 suppressed the LPS-induced migration and proliferation of breast cancer cells. Additionally, treatment with LPS caused approximately six- and three-fold increases in COX-2 mRNA and protein expression, respectively, compared to the controls. The LPS-induced elevations in the COX-2 mRNA and protein levels were suppressed by BTP2 to the control levels. In addition to its effect on COX-2, BTP2 also suppressed the LPS-induced productions of PGE2, IL-6, IL-8, and VEGF. Conversely, SOCE induction using Thapsigargin enhanced the LPS-induced inflammation, migration, and proliferation of breast cancer cells. Collectively, these results provide evidence for the potentially important role of SOCE in inflammation-induced breast cancer progression processes. Thus, we argue that the current study may provide novel targets for designing new therapeutic approaches for the treatment of breast cancer.

Targeting a novel circITCH/miR-421/BTG1 axis is effective to suppress the malignant phenotypes in hepatocellular carcinoma (HCC) cells

Circular RNA-based competing endogenous RNA (ceRNA) networks contribute to the initiation and development of various types of cancer, including hepatocellular carcinoma (HCC). Although a novel circular RNA itchy E3 ubiquitin protein ligase (circITCH) is identified as a tumor suppressor in HCC, its detailed molecular mechanisms have not been fully delineated. The present study was designed to resolve this issue, and we firstly verified that circITCH suppressed the malignant phenotypes in HCC cells by regulating a novel miR-421/B-cell translocation gene 1 (BTG1) axis. Specifically, through performing the Real-Time qPCR analysis, we noticed that circITCH expression in HCC tumor tissues or cell lines were significantly lower than that in adjacent normal tissues or normal hepatocytes, and the expression levels of circITCH were negatively correlated with tumor size and TNM stage in HCC patients. Next, our functional experiments confirmed that overexpression of circITCH induced cell cycle arrest and apoptosis, and reduced cell viability and colony forming ability in Hep3B and Huh7 cells. Mechanically, bioinformatics analysis, RNA immunoprecipitation and luciferase reporter assay demonstrated that circITCH served as RNA sponges for miR-421 to elevate BTG1 levels in HCC cells. The rescuing experiments verified that upregulation of miR-421 promoted cell viability and colony formation, and reduced apoptosis, which were abrogated by overexpression of circITCH or BTG1. In conclusion, this study identified a novel circITCH/miR-421/BTG1 axis that restrained the development of HCC, and our findings provided novel biomarkers for the treatment of this disease.

The Role of TLR4 in the Immunotherapy of Hepatocellular Carcinoma: Can We Teach an Old Dog New Tricks?

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and is a leading cause of cancer-related death worldwide. Immunotherapy has emerged as the mainstay treatment option for unresectable HCC. Toll-like receptor 4 (TLR4) plays a crucial role in the innate immune response by recognizing and responding primarily to bacterial lipopolysaccharides. In addition to its role in the innate immune system, TLR4 has also been implicated in adaptive immunity, including specific anti-tumor immune responses. In particular, the TLR4 signaling pathway seems to be involved in the regulation of several cancer hallmarks, such as the continuous activation of cellular pathways that promote cell division and growth, the inhibition of programmed cell death, the promotion of several invasion and metastatic mechanisms, epithelial-to-mesenchymal transition, angiogenesis, drug resistance, and epigenetic modifications. Emerging evidence further suggests that TLR4 signaling holds promise as a potential immunotherapeutic target in HCC. The aim of this review was to explore the multilayer aspects of the TLR4 signaling pathway, regarding its role in liver diseases and HCC, as well as its potential utilization as an immunotherapy target for HCC.

Pattern recognition receptors in the development of nonalcoholic fatty liver disease and progression to hepatocellular carcinoma: An emerging therapeutic strategy

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and has become the leading chronic liver disease worldwide. NAFLD is viewed as the hepatic manifestation of metabolic syndrome, ranging from simple steatosis and nonalcoholic steatohepatitis (NASH) to advanced fibrosis, eventually leading to cirrhosis and hepatocellular carcinoma (HCC). The pathogenesis of NAFLD progression is still not clear. Pattern recognition receptor (PRR)-mediated innate immune responses play a critical role in the initiation of NAFLD and the progression of NAFLD-related HCC. Toll-like receptors (TLRs) and the cyclic GMP-AMP (cGAMP) synthase (cGAS) are the two major PRRs in hepatocytes and resident innate immune cells in the liver. Increasing evidence indicates that the overactivation of TLRs and the cGAS signaling pathways may contribute to the development of liver disorders, including NAFLD progression. However, induction of PRRs is critical for the release of type I interferons (IFN-I) and the maturation of dendritic cells (DCs), which prime systemic antitumor immunity in HCC therapy. In this review, we will summarize the emerging evidence regarding the molecular mechanisms of TLRs and cGAS in the development of NAFLD and HCC. The dysfunction of PRR-mediated innate immune response is a critical determinant of NAFLD pathology; targeting and selectively inhibiting TLRs and cGAS signaling provides therapeutic potential for treating NALF-associated diseases in humans.

Novel pyrrolopyrimidine derivatives: design, synthesis, molecular docking, molecular simulations and biological evaluations as antioxidant and anti-inflammatory agents

Current medical approaches to control the Covid-19 pandemic are either to directly target the SARS-CoV-2 via innovate a defined drug and a safe vaccine or indirectly target the medical complications of the virus. One of the indirect strategies for fighting this virus has been mainly dependent on using anti-inflammatory drugs to control cytokines storm responsible for severe health complications. We revealed the discovery of novel fused pyrrolopyrimidine derivatives as promising antioxidant and anti-inflammatory agents. The newly synthesised compounds were evaluated for their in vitro anti-inflammatory activity using RAW264.7 cells after stimulation with lipopolysaccharides (LPS). The results revealed that 3a, 4b, and 8e were the most potent analogues. Molecular docking and simulations of these compounds against COX-2, TLR-2 and TLR-4 respectively was performed. The former results were in line with the biological data and proved that 3a, 4b and 8e have potential antioxidant and anti-inflammatory effects.

Gut microbiota changes and biological mechanism in hepatocellular carcinoma after transarterial chemoembolization treatment

Background and aims

Intestinal flora is closely associated with the occurrence and development of hepatocellular carcinoma (HCC). However, gut microbial changes and biological mechanisms in HCC after transarterial chemoembolization (TACE) treatment are rarely reported.

Methods

We evaluated changes in intestinal flora after TACE in rabbit HCC models and assessed the impact of these changes on the disease. Twenty-four rabbit VX2 HCC models were established and intestinal flora structures, intestinal barrier function, changes in blood lipopolysaccharide (LPS) levels, Toll-like receptor 4 (TLR4), Cyclooxygenase-2 (COX-2), and p-signal transducer and activator of transcription 3(p-STAT3) protein expression levels were studied after TACE treatment.

Results

Compared with healthy rabbits, the intestinal flora in HCC models exhibited structural changes; intestinal barrier function was decreased, and increased LPS levels entered the circulation. A short-term follow-up after TACE showed the procedure partially reversed the intestinal microflora disorder caused by the tumor: intestinal barrier and liver functions were improved, intestinal LPS levels in the blood were reduced, and liver metabolism toward LPS was enhanced. Correlation analyses of the first 75 significantly changed bacteria with clinical factors showed that harmful bacteria had decreased and beneficial bacteria increased. Blood LPS levels and downstream signaling molecule TLR4, COX-2, and p-STAT3 protein expression levels were reduced, which correlated with tumor drug resistance and invasion capabilities.

Conclusions

We first characterized gut microbiota changes and biological mechanisms in HCC after TACE treatment. Our data provide a theoretical research basis for TACE combined with an intestinal flora intervention and systemic chemotherapy.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription- quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ- BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

Persistent TLR4 Activation Promotes Hepatocellular Carcinoma Growth through Positive Feedback Regulation by LIN28A/Let-7g miRNA

Chronic inflammation caused by liver damage or infection plays an important role in the development and progression of hepatocellular carcinoma (HCC). The activation of Toll-like receptors 4 (TLR4) is involved in HCC tumorigenesis. Moreover, high TLR4 expression in HCC has been linked to poor prognosis. Although the expression of TLR4 in HCC is relatively low compared to hematopoietic cells, it is important to explore the molecular mechanism leading to the elevation of TLR4 in HCC. In this study, we aimed to investigate the positive regulating loop for TLR4 expression in HCC in response to chronic inflammation. Our results confirm that the mRNA expression of TLR4 and proinflammatory cytokines, including interleukin 6 (IL6) and C-C motif chemokine ligand 2 (CCL2), positively correlate in human HCC samples. High TLR4 expression in HCC is more susceptible to lipopolysaccharide (LPS); TLR4 activation in HCC provides growth and survival advantages and thus promotes tumorigenesis. It has been shown that the LIN28/let-7 microRNA (miRNA) axis is a downstream effector of the TLR4 signal pathway, and let-7 miRNA is a potential post-transcriptional regulator for TLR4. Thus, we investigated the correlation between TLR4 and LIN28A mRNA and let-7g miRNA in HCC clinical samples and found that the expression of TLR4 was positively correlated with LIN28A and negatively correlated with let-7g miRNA. Moreover, by culturing PLC/PRF5 (PLC5) HCC cells in low-dose LPS-containing medium to mimic chronic inflammation for persistent TLR4 activation, the mRNA and protein levels of TLR4 and LIN28A were elevated, and let-7g miRNA was decreased. Furthermore, the 3' untranslated region (3’UTR) of TLR4 mRNA was shown to be the target of let-7g miRNA, suggesting that inhibition of let-7g miRNA is able to increase TLR4 mRNA. While parental PLC5 cells have a low susceptibility to LPS-induced cell growth, long-term LPS exposure for PLC5 cells leads to increased proliferation, cytokine expression and stemness properties. In conclusion, our studies demonstrate positive feedback regulation for chronic TLR4 activation in the modulation of TLR4 expression level through the LIN28A/let-7g pathway in HCC and suggest a connection between chronic inflammation and TLR4 expression level in HCC for promoting tumorigenesis.

MicroRNAs at the Crossroad between Immunoediting and Oncogenic Drivers in Hepatocellular Carcinoma

Simple Summary

In recent years, treatments enhancing the antitumor immune response have revealed a new promising approach for advanced hepatocellular carcinoma (HCC). Beside favorable results in about one third of patients, much still remains to be done to face primary nonresponse, early, and late disease reactivation. Understanding the mechanisms underneath immune system modulation by immune checkpoint inhibitors in HCC might give additional opportunities for patient selection and combined approaches. MicroRNAs have emerged as relevant modulators of cancer cell hallmarks, including aberrant proliferation, invasion and migration capabilities, epithelial-to-mesenchymal transition, and glycolytic metabolism. At the same time, they contribute to the immune system development, response, and programs activation, with particular regard towards regulatory functions. Thus, miRNAs are relevant not only in cancer cells’ biology, but also in the immune response and interplay between cancer, microenvironment, and immune system.

Abstract

Treatments aimed to reverse the tumor-induced immune tolerance represent a promising approach for advanced hepatocellular carcinoma (HCC). Notwithstanding, primary nonresponse, early, and late disease reactivation still represent major clinical challenges. Here, we focused on microRNAs (miRNAs) acting both as modulators of cancer cell hallmarks and immune system response. We outlined the bidirectional function that some oncogenic miRNAs play in the differentiation and program activation of the immune system development and, at the same time, in the progression of HCC. Indeed, the multifaceted spectrum of miRNA targets allows the modulation of both immune-associated factors and oncogenic or tumor suppressor drivers at the same time. Understanding the molecular changes contributing to disease onset, progression, and resistance to treatments might help to identify possible novel biomarkers for selecting patient subgroups, and to design combined tailored treatments to potentiate antitumor approaches. Preliminary findings seem to argue in favor of a bidirectional function of some miRNAs, which enact an effective modulation of molecular pathways driving oncogenic and immune-skipping phenotypes associated with cancer aggressiveness. The identification of these miRNAs and the characterization of their ‘dual’ role might help to unravel novel biomarkers identifying those patients more likely to respond to immune checkpoint inhibitors and to identify possible therapeutic targets with both antitumor and immunomodulatory functions. In the present review, we will focus on the restricted panel of miRNAs playing a bidirectional role in HCC, influencing oncogenic and immune-related pathways at once. Even though this field is still poorly investigated in HCC, it might represent a source of candidate molecules acting as both biomarkers and therapeutic targets in the setting of immune-based treatments.

Hepatocellular Carcinoma: How the Gut Microbiota Contributes to Pathogenesis, Diagnosis, and Therapy

The gut microbiota is gaining increasing attention, and the concept of the "gut-liver axis" is gradually being recognized. Leaky gut resulting from injury and/or inflammation can cause the translocation of flora to the liver. Microbiota-associated metabolites and components mediate the activation of a series of signalling pathways, thereby playing an important role in the development of hepatocellular carcinoma (HCC). For this reason, targeting the gut microbiota in the diagnosis, prevention, and treatment of HCC holds great promise. In this review, we summarize the gut microbiota and the mechanisms by which it mediates HCC development, and the characteristic alterations in the gut microbiota during HCC pathogenesis. Furthermore, we propose several strategies to target the gut microbiota for the prevention and treatment of HCC, including antibiotics, probiotics, faecal microbiota transplantation, and immunotherapy.

Prostaglandin E2 and Receptors: Insight Into Tumorigenesis, Tumor Progression, and Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common primary liver cancer with ∼750,000 annual incidence rates globally. PGE2, usually known as a pro-inflammatory cytokine, is over-expressed in various human malignancies including HCC. PGE2 binds to EP receptors in HCC cells to influence tumorigenesis or enhance tumor progression through multiple pathways such as EP1-PKC-MAPK, EP2-PKA-GSK3β, and EP4-PKA-CREB. In the progression of hepatocellular carcinoma, PGE2 can promote the proliferation and migration of liver cancer cells by affecting hepatocytes directly and the tumor microenvironment (TME) through ERK/COX-2/PGE2 signal pathway in hepatic stellate cells (HSC). For the treatment of hepatocellular carcinoma, there are drugs such as T7 peptide and EP1 antagonist ONO-8711 targeting Cox-2/PGE2 axis to inhibit tumor progression. In conclusion, PGE2 has been shown to be a traditional target with pleiotropic effects in tumorigenesis and progression of HCC that could be used to develop a new potential clinical impact. For the treatment study focusing on the COX-PGE2 axis, the exclusive usage of non-steroidal anti-inflammatory agents (NSAIDs) or COX-2-inhibitors may be replaced by a combination of selective EP antagonists and traditional anti-tumoral drugs to alleviate severe side effects and achieve better outcomes.

Fructose-1,6-bisphosphate prevents pregnancy loss by inducing decidual COX-2+ macrophage differentiation

Decidualization is an intricate biological process in which extensive remodeling of the endometrium occurs to support the development of an implanting blastocyst. However, the immunometabolic mechanisms underlying this process are still largely unknown. We found that the decidualization process is accompanied by the accumulation of fructose-1,6-bisphosphate (FBP). The combination of FBP with pyruvate kinase M stimulated IL-27 secretion by endometrial stromal cells in an ERK/c-FOS-dependent manner. IL-27 induced decidual COX-2⁺ M2-like macrophage differentiation, which promotes decidualization, trophoblast invasion, and maternal-fetal tolerance. Transfer of Ptgs2⁺/COX-2⁺ macrophages prevented fetal loss in Il27ra-deleted pregnant mice. FBP levels were low in plasma and decidual tissues of patients with unexplained recurrent spontaneous abortion. In therapeutic studies, FBP supplementation significantly improved embryo loss by up-regulation of IL-27-induced COX-2⁺ macrophage differentiation in a mouse model of spontaneous abortion. These findings collectively provide a scientific basis for a potential therapeutic strategy to prevent pregnancy loss.

The crosstalk among TLR2, TLR4 and pathogenic pathways; a treasure trove for treatment of diabetic neuropathy

Diabetes is correlated with organ failures as a consequence of microvascular diabetic complications, including neuropathy, nephropathy, and retinopathy. These difficulties come with serious clinical manifestations and high medical costs. Diabetic neuropathy (DN) is one of the most prevalent diabetes complications, affecting at least 50% of diabetic patients with long disease duration. DN has serious effects on patients' life since it interferes with their daily physical activities and causes psychological comorbidities. There are some potential risk factors for the development of neuropathic injuries. It has been shown that inflammatory mechanisms play a pivotal role in the progression of DN. Among inflammatory players, TLR2 and TLR4 have gained immense importance because of their ability in recognizing distinct molecular patterns of invading pathogens and also damage-associated molecular patterns (DAMPs) providing inflammatory context for the progression of a wide array of disorders. We, therefore, sought to explore the possible role of TLR2 and TLR4 in DN pathogenesis and if whether manipulating TLRs is likely to be successful in fighting off DN.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ-BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents: Synthesis and biological evaluation

Glioblastoma is one of the most lethal brain tumors. The crucial chemotherapy is mainly alkylating agents with modest clinical success. Given this desperate need and inspired by the encouraging results of a phase II trial via concomitant Topo I inhibitor plus COX-2 inhibitor, we designed a series of N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents based on structure modification on 1,5-naphthyridine derivatives (Topo I inhibitors). Notably, the target compounds I-1 (33.61 ± 1.15 μM) and I-8 (45.01 ± 2.37 μM) were confirmed to inhibit COX-2, while a previous reported compound (1,5-naphthyridine derivative) resulted nearly inactive towards COX-2 (IC₅₀ > 150 μM). Besides, I-1 and I-8 exhibited higher anti-proliferation, anti-migration, anti-invasion effects than the parent compound 1,5-naphthyridine derivative, suggesting the success of modification based on the parent. Moreover, I-1 obviously repressed tumor growth in the C6 glioma orthotopic model (TGI = 66.7%) and U87MG xenograft model (TGI = 69.4%). Besides, I-1 downregulated PGE₂, VEGF, MMP-9, and STAT3 activation, upregulated E-cadherin in the orthotopic model. More importantly, I-1 showed higher safety than temozolomide and different mechanism from temozolomide in the C6 glioma orthotopic model. All the evidence demonstrated that N-2-(phenylamino) benzamide derivatives as novel anti-glioblastoma agents could be promising for the glioma management.

FSTL1 Secreted by Activated Fibroblasts Promotes Hepatocellular Carcinoma Metastasis and Stemness

The tumor microenvironment plays a critical role in maintaining the immature phenotype of tumor-initiating cells (TIC) to promote cancer. Hepatocellular carcinoma (HCC) is a unique disease in that it develops in the setting of fibrosis and cirrhosis. This pathologic state commonly shows an enrichment of stromal myofibroblasts, which constitute the bulk of the tumor microenvironment and contribute to disease progression. Follistatin-like 1 (FSTL1) has been widely reported as a proinflammatory mediator in different fibrosis-related and inflammatory diseases. Here we show FSTL1 expression to be closely correlated with activated fibroblasts and to be elevated in regenerative, fibrotic, and disease liver states in various mouse models. Consistently, FSTL1 lineage cells gave rise to myofibroblasts in a CCL₄-induced hepatic fibrosis mouse model. Clinically, high FSTL1 in fibroblast activation protein-positive (FAP⁺) fibroblasts were significantly correlated with more advanced tumors in patients with HCC. Although FSTL1 was expressed in primary fibroblasts derived from patients with HCC, it was barely detectable in HCC cell lines. Functional investigations revealed that treatment of HCC cells and patient-derived 3D organoids with recombinant FSTL1 or with conditioned medium collected from hepatic stellate cells or from cells overexpressing FSTL1 could promote HCC growth and metastasis. FSTL1 bound to TLR4 receptor, resulting in activation of AKT/mTOR/4EBP1 signaling. In a preclinical mouse model, blockade of FSTL1 mitigated HCC malignancy and metastasis, sensitized HCC tumors to sorafenib, prolonged survival, and eradicated the TIC subset. Collectively, these data suggest that FSTL1 may serve as an important novel diagnostic/prognostic biomarker and therapeutic target in HCC. SIGNIFICANCE: This study shows that FSTL1 secreted by activated fibroblasts in the liver microenvironment augments hepatocellular carcinoma malignancy, providing a potential new strategy to improve treatment of this aggressive disease.

Differential Expression of the TLR4 Gene in Pan-Cancer and Its Related Mechanism

Previous studies have revealed the relationship between toll-like receptor 4 (TLR4) polymorphisms and cancer susceptibility. However, the relationship between TLR4 and prognosis and immune cell infiltration in pan-cancer patients is still unclear. Through the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases, the distinct expression of the TLR4 gene in 24 tumors and normal tissues was analyzed. Univariate Cox proportional hazards regression analysis was used to identify the cancer types whose TLR4 gene expression was related to prognosis. The relationship between TLR4 and tumor cell immune invasion was studied. Spearman's rank correlation coefficient was used to analyze the relationship among TLR4 and immune neoantigens, tumor mutation burden (TMB), microsatellite instability (MSI), DNA repair genes, and DNA methylation. Gene Set Enrichment Analysis (GSEA) was used to identify the tumor-related pathways that the TLR4 gene was highly expressed in; the expression of the TLR4 gene was verified with the Human Protein Atlas (HPA) database. Low expression of TLR4 was associated with an inferior prognosis in kidney renal clear cell carcinoma (KIRC), skin cutaneous melanoma (SKCM), and uterine corpus endometrial carcinoma (UCEC), while high expression was related to a poor prognosis in head and neck squamous cell carcinoma (HNSC), prostate adenocarcinoma (PRAD), stomach adenocarcinoma (STAD), and testicular germ cell tumor (TGCT). The expression of TLR4 was negatively correlated with the expression of B cells in STAD. The expression of TLR4 was positively correlated with the infiltration of B cells, CD4 and CD8 T cells, neutrophils, macrophages, and dendritic cells in STAD, KIRC, UCEC, TGCT, and SKCM. The expression of the TLR4 gene in KIRC, SKCM, STAD, TGCT, and UCEC was highly correlated with inducible T-cell costimulator (ICOS), cytotoxic T lymphocyte-associated molecule 4 (CTLA4), and CD28 immune checkpoints. Spearman's rank correlation coefficient showed that the expression of TLR4 gene was significantly correlated with TMB in STAD and UCEC and was prominently correlated with MSI in TGCT, STAD, and SKCM. The expression of the TLR4 gene was highly correlated with MLH1, MSH2, and MSH6 in KIRC, SKCM, and STAD. The expression of the TLR4 gene was remarkably correlated with the methyltransferases DNA methyltransferase 2 (DNMT2) and DNA methyltransferase 3-beta (DNMT3B) in SKCM and STAD. Enrichment analysis showed that TLR4 was highly expressed in the chemokine signaling pathway and the cell adhesion molecule and cytokine receptor interaction pathway. In summary, the expression of TLR4 is linked to the prognosis of KIRC, SKCM, STAD, TGCT, and UCEC patients and the level of immune infiltration of CD4, CD8 T cells, macrophages, neutrophils, and dendritic cells.

Pattern recognition receptors in health and diseases

Pattern recognition receptors (PRRs) are a class of receptors that can directly recognize the specific molecular structures on the surface of pathogens, apoptotic host cells, and damaged senescent cells. PRRs bridge nonspecific immunity and specific immunity. Through the recognition and binding of ligands, PRRs can produce nonspecific anti-infection, antitumor, and other immunoprotective effects. Most PRRs in the innate immune system of vertebrates can be classified into the following five types based on protein domain homology: Toll-like receptors (TLRs), nucleotide oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), C-type lectin receptors (CLRs), and absent in melanoma-2 (AIM2)-like receptors (ALRs). PRRs are basically composed of ligand recognition domains, intermediate domains, and effector domains. PRRs recognize and bind their respective ligands and recruit adaptor molecules with the same structure through their effector domains, initiating downstream signaling pathways to exert effects. In recent years, the increased researches on the recognition and binding of PRRs and their ligands have greatly promoted the understanding of different PRRs signaling pathways and provided ideas for the treatment of immune-related diseases and even tumors. This review describes in detail the history, the structural characteristics, ligand recognition mechanism, the signaling pathway, the related disease, new drugs in clinical trials and clinical therapy of different types of PRRs, and discusses the significance of the research on pattern recognition mechanism for the treatment of PRR-related diseases.

In Situ Vaccination as a Strategy to Modulate the Immune Microenvironment of Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is a highly prevalent malignancy that develops in patients with chronic liver diseases and dysregulated systemic and hepatic immunity. The tumor microenvironment (TME) contains tumor-associated macrophages (TAM), cancer-associated fibroblasts (CAF), regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) and is central to mediating immune evasion and resistance to therapy. The interplay between these cells types often leads to insufficient antigen presentation, preventing effective anti-tumor immune responses. In situ vaccines harness the tumor as the source of antigens and implement sequential immunomodulation to generate systemic and lasting antitumor immunity. Thus, in situ vaccines hold the promise to induce a switch from an immunosuppressive environment where HCC cells evade antigen presentation and suppress T cell responses towards an immunostimulatory environment enriched for activated cytotoxic cells. Pivotal steps of in situ vaccination include the induction of immunogenic cell death of tumor cells, a recruitment of antigen-presenting cells with a focus on dendritic cells, their loading and maturation and a subsequent cross-priming of CD8+ T cells to ensure cytotoxic activity against tumor cells. Several in situ vaccine approaches have been suggested, with vaccine regimens including oncolytic viruses, Flt3L, GM-CSF and TLR agonists. Moreover, combinations with checkpoint inhibitors have been suggested in HCC and other tumor entities. This review will give an overview of various in situ vaccine strategies for HCC, highlighting the potentials and pitfalls of in situ vaccines to treat liver cancer.

CircRNA hsa_circ_0110102 inhibited macrophage activation and hepatocellular carcinoma progression via miR-580-5p/PPARα/CCL2 pathway

Circular RNAs (circRNAs) have critical regulatory roles in tumor biology. However, their contributions in hepatocellular carcinoma (HCC) still remain enigmatic. The present study aimed to investigate the molecular mechanisms underlying the involvement of hsa_circ_0110102 in the occurrence and development of HCC. The expression level of hsa_circ_0110102 was significantly downregulated in HCC cell lines and tissues, which was associated with poor prognosis. Knockdown hsa_circ_0110102 significantly promoted cell proliferation, migration, and invasion. Moreover, the interaction between hsa_circ_0110102 and miR-580-5p was predicted and verified by luciferase assay and RNA pull-down. The findings indicated that hsa_circ_0110102 functioned as a sponge for miR-580-5p. Moreover, miR-580-5p directly bound to the 3' UTR of PPARα, which decreased the production and release of C-C chemokine ligand 2 (CCL2) in HCC cells. CCL2 could activate the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway in macrophage via FoxO1 in a p38 MAPK-dependent manner. Furthermore, the Δ256 mutant of FoxO1 showed no activation effect. These results concluded that hsa_circ_0110102 acted as a sponge for miR-580-5p and inhibited CCL2 secretion into tumor microenvironment by decrease the expression of PPARα in HCC cells, then inhibited the pro-inflammatory cytokine release from macrophages by regulating the COX-2/PGE2 pathway. In conclusion, hsa_circ_0110102 served as a potential prognostic predictor or therapeutic target for HCC.

Host defense peptide LL-37 is involved in the regulation of cell proliferation and production of pro-inflammatory cytokines in hepatocellular carcinoma cells

Recent studies on the roles and mechanisms of LL-37 have demonstrated that LL-37 can either serve as a tumor promoter or a tumor suppressor in different cancers. The expression and function of LL-37 in hepatocellular carcinoma (HCC), however, remain unclear. In the present study, we confirmed the down-regulation of LL-37 in HCC tissues and the synthetic LL-37 peptide reduced the viability of HCC cells in a dose-dependent manner. Furthermore, we demonstrated that LL-37 peptide significantly delayed G1-S transition in Huh7 but not in HepG2 cells by suppressing CyclinD1-CDK4-p21 checkpoint signaling pathway. However, LL-37 caused no obvious apoptosis both in Huh7 and HepG2 cells, though the expression of apoptosis-related genes was strongly changed through qRT-PCR analysis, hinting at the possibility that LL-37 participates in regulating the apoptosis of HCC cells, but may not the only mechanism. Besides, we also identified that LL-37 treatment strongly inhibited the mRNA expression of TLR4 both in Huh7 and HepG2 cells, accompanied with the reduced expression of genes responsible for pro-inflammatory cytokines, including IL-8 and IL-6. In conclusion, our research suggested that LL-37 may be associated with the development of HCC.

Total flavonoids of Radix Tetrastigma suppress inflammation-related hepatocellular carcinoma cell metastasis

This study aimed to investigate the effects of the total flavonoids of Radix Tetrastigma (RTF) on inflammation-related hepatocellular carcinoma (HCC) development. Extracted RTF was diluted to different concentrations for subsequent experiments. HCC cells were cotreated with lipopolysaccharide (LPS) and RTF to investigate the effects of RTF on LPS-stimulated HCC cells. A CCK-8 kit was used to measure cell proliferation. Apoptosis was detected with a flow cytometer. Cell migration and invasion were quantified by wound healing and Transwell assays, respectively. The expression of TLR4 and COX-2 and activation of the NF-κB pathway were determined by Western blotting. Treatment with LPS significantly enhanced cell proliferation and decreased the apoptosis rate, while cell migration and invasion were notably upregulated. RTF suppressed the proliferation and invasion induced by LPS stimulation and promoted HCC cell apoptosis. The protein levels of Bax and cleaved caspase-3 were decreased and that of Bcl-2 was increased by LPS in HCC cells, which could be rescued by RTF. RTF significantly inhibited the LPS-induced expression of the proinflammatory mediators IL-6 and IL-8 in HCC cells. Mechanistically, with RTF treatment, the upregulated expression of TLR4 and COX-2 induced by LPS was obviously downregulated. Furthermore, the phosphorylation of NF-κB/p65 was significantly decreased in LPS-stimulated cells after supplementation with RTF. Our study suggests that RTF exerts a significant inhibitory effect on the LPS-induced enhancement of the malignant behaviors of HCC cells via inactivation of TLR4/NF-κB signaling. RTF may be a promising chemotherapeutic agent to limit HCC development and inflammation-mediated metastasis.

High TLR4 expression predicts a poor prognosis after esophagectomy for advanced thoracic esophageal squamous cell carcinoma

BACKGROUND

Poor oral health is an independent risk factor for upper aerodigestive tract cancers, including esophageal squamous cell carcinoma (ESCC). The pattern recognition receptor Toll-like receptor 4 (TLR4) recognizes lipopolysaccharide in the cell walls of Gram-negative periodontal pathogens associated with the development and progression of ESCC. It is, therefore, plausible that TLR4 plays a crucial role in the pathogenesis of ESCC.

METHODS

We used an ESCC tissue microarray to confirm expression of TLR4 in patients with ESCC and to determine whether TLR4 expression status correlates with the clinicopathological features of these patients or their prognosis after esophagectomy. We also tested whether the combined expression statuses of TLR4 and TLR3 better correlate with prognosis in these patients than either parameter alone.

RESULTS

Clinical ESCC samples from all 177 patients tested showed expression of TLR4. Moreover, high TLR4 expression (3 + and 2 +) correlated with poorer 5-year overall survival after esophagectomy than lower TLR4 expression (1 +) (p = 0.0491). Patients showing high TLR4 expression tended to have a poorer prognosis whether treated with surgery alone or with surgery and adjuvant chemotherapy. Univariate and multivariate analyses showed TLR4 expression status to be an independent prognostic factor affecting 5-year overall survival. Patients exhibiting high TLR4 expression with low TLR3 expression had a much poorer prognosis than other patients (p = < 0.0001).

CONCLUSION

High TLR4 expression predicts a poor prognosis in advanced thoracic ESCC patients after esophagectomy.

NLRC3 silencing accelerates the invasion of hepatocellular carcinoma cell via IL-6/JAK2/STAT3 pathway activation

Nucleotide-binding domain, leucine-rich repeat family with a caspase activation and recruitment domain 3 (NLRC3) participates in both immunity and cancer. The aim of this study was to determine the role of NLRC3 in human hepatocellular carcinoma (HCC) and the underlying mechanisms. We collected human liver tissues from nonalcoholic steatohepatitis (NASH), HCC, and adjacent normal tissues to characterize the pattern of NLRC3 expression by real-time quantitative polymerase chain reaction and immunohistochemistry. Then, we used the HCC cell line, HuH-7, transfected with small interfering RNA to silence the NLRC3 expression. 5-Ethynyl-2'-deoxyuridine assay, scratch assay, and transwell invasion assay were used for assessing proliferation, migration, and invasion, respectively. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were conducted to assess cell apoptosis. The expression of NLRC3 was reduced in human HCC tissues, compared with normal liver and nonalcoholic steatohepatitis tissues. After knocking down of NLRC3, the proliferation, migration, and invasion were increased in HuH-7 cells. And flow cytometry and TUNEL assay showed that HuH-7 cell apoptosis was suppressed after NLRC3 knockdown. As for the underlying mechanisms, knockdown of NLRC3 in HuH-7 cells was associated with the activation of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) pathway under interleukin-6 (IL-6) stimulation. NLRC3 expression was downregulated in human HCC tissues. NLRC3 silencing in HuH-7 cells can promote the proliferation, migration, and invasion of hepatocellular carcinoma cells. JAK2/STAT3 pathway activation induced by IL-6 may be the underlying mechanism for HCC when NLRC3 expression is silenced. And the invasion of HuH-7 cells was partially suppressed by the STAT3 specific inhibitor (cryptotanshinone). Therefore, NLRC3 may play a significant role in HCC and might be a therapeutic target for the treatment of HCC.

STAT3: A key signaling molecule for converting cold to hot tumors

Tumors can be classified as cold or hot according to the degree of immune cell infiltration into tumor tissues; cold tumors are insensitive to either chemotherapy or immunotherapy and are associated with poor prognosis. Recent studies have shown that STAT3 signaling molecules hinder the conversion of cold to hot tumors by regulating immunosuppressive molecule secretion and immunosuppressive cell functions. This review aims to present the most recent studies on how STAT3 regulates cold tumor formation and discuss its research status in cancer therapy. We also present insight for designing new therapeutic strategies to "heat" tumors and provide a reference for tumor immunotherapy.

Activation of STAT3 is a key event in TLR4 signaling-mediated melanoma progression

Malignant melanoma is aggressive and has a high mortality rate. Toll-like receptor 4 (TLR4) has been linked to melanoma growth, angiogenesis and metastasis. However, signal transduction mediated by TLR4 for driving melanoma progression is not fully understood. Signal transducer and activator of transcription 3 (STAT3) has been identified as a major oncogene in melanoma progression. We found: that TLR4 expression positively correlates with activation/phosphorylation of STAT3 in human melanoma samples; that TLR4 ligands activate STAT3 through MYD88 and TRIF in melanoma cells; and that intratumoral activation of TLR4 increases STAT3 activation in the tumor and promotes tumor growth, angiogenesis, epithelial-mesenchymal transition (EMT) and the formation of an immunosuppressive tumor microenvironment in mice. Further, we found that the effects mediated by activating TLR4 are weakened by suppressing STAT3 function with a dominant negative STAT3 variant in melanoma. Collectively, our work identifies STAT3 activation as a key event in TLR4 signaling-mediated melanoma progression, shedding new light on the pathophysiology of melanoma.

The mechanistic, diagnostic and therapeutic novel nucleic acids for hepatocellular carcinoma emerging in past score years

Despite The Central Dogma states the destiny of gene as 'DNA makes RNA and RNA makes protein', the nucleic acids not only store and transmit genetic information but also, surprisingly, join in intracellular vital movement as a regulator of gene expression. Bioinformatics has contributed to knowledge for a series of emerging novel nucleic acids molecules. For typical cases, microRNA (miRNA), long noncoding RNA (lncRNA) and circular RNA (circRNA) exert crucial role in regulating vital biological processes, especially in malignant diseases. Due to extraordinarily heterogeneity among all malignancies, hepatocellular carcinoma (HCC) has emerged enormous limitation in diagnosis and therapy. Mechanistic, diagnostic and therapeutic nucleic acids for HCC emerging in past score years have been systematically reviewed. Particularly, we have organized recent advances on nucleic acids of HCC into three facets: (i) summarizing diverse nucleic acids and their modification (miRNA, lncRNA, circRNA, circulating tumor DNA and DNA methylation) acting as potential biomarkers in HCC diagnosis; (ii) concluding different patterns of three key noncoding RNAs (miRNA, lncRNA and circRNA) in gene regulation and (iii) outlining the progress of these novel nucleic acids for HCC diagnosis and therapy in clinical trials, and discuss their possibility for clinical applications. All in all, this review takes a detailed look at the advances of novel nucleic acids from potential of biomarkers and elaboration of mechanism to early clinical application in past 20 years.

LPS-induced inflammation desensitizes hepatocytes to Fas-induced apoptosis through Stat3 activation-The effect can be reversed by ruxolitinib

Recent studies have established a concept of tumour necrosis factor‐α (TNF‐α)/Fas signalling crosstalk, highlighting TNF‐α as a critical cytokine in sensitizing hepatocytes to death induced by Fas activation. However, in the exact inflammatory response, besides TNF‐α, many other mediators, that might modulate apoptotic response differentially, are released. To resolve the issue, we studied the effects of lipopolysaccharide (LPS), one of the crucial inductors of inflammation in the liver, on apoptotic outcome. We show that LPS‐induced inflammation diminishes the sensitivity of hepatocytes to Fas stimulus in vivo at caspase‐8 level. Analysis of molecular mechanisms revealed an increased expression of various pro‐inflammatory cytokines in non‐parenchymal liver cells and hepatocyte‐specific increase in Bcl‐xL, associated with signal transducer and activator of transcription 3 (Stat3) phosphorylation. Pre‐treatment with ruxolitinib, a selective Janus kinase (JAK) 1/2 inhibitor, prevented the LPS‐induced Stat3 phosphorylation and restored the sensitivity of hepatocytes to Fas‐mediated apoptosis. Furthermore, ruxolitinib pre‐treatment diminished the LPS‐induced Bcl‐xL up‐regulation without an inhibitory effect on LPS‐induced expression of pro‐inflammatory cytokines. In summary, although the reports are showing that the effects of isolated pro‐inflammatory mediators, such as TNF‐α or neutrophils, are pro‐apoptotic, the overall effect of inflammatory milieu on hepatocytes in vivo is Stat3‐dependent desensitization to Fas‐mediated apoptosis.

Increased neutrophil extracellular traps promote metastasis potential of hepatocellular carcinoma via provoking tumorous inflammatory response

Background

The propensity of the activated neutrophils to form extracellular traps (NETs) is demonstrated in multiple inflammatory conditions. In this study, we investigated the roles of NETs in metastasis of hepatocellular carcinoma (HCC) and further explored the underlying mechanism of how NETs affect metastasis as well as the therapeutic value.

Methods

The neutrophils were isolated from the blood of human HCC patients and used to evaluate the formation of NETs. The expression of NET markers was detected in tumor specimens. A LPS-induced NET model was used to investigate the role of NETs on HCC metastasis. RNA-seq was performed to identify the key molecular event triggered by NETs, and their underlying mechanism and therapeutic significance were explored using both in vitro and in vivo assays.

Results

NET formation was enhanced in neutrophils derived from HCC patients, especially those with metastatic HCCs. NETs trapped HCC cells and subsequently induced cell-death resistance and enhanced invasiveness to trigger their metastatic potential, which was mediated by internalization of NETs into trapped HCC cells and activation of Toll-like receptors TLR4/9-COX2 signaling. Inhibition of TLR4/9-COX2 signaling abrogated the NET-aroused metastatic potential. A combination of DNase 1 directly wrecking NETs with anti-inflammation drugs aspirin/hydroxychloroquine effectively reduced HCC metastasis in mice model.

Conclusions

NETs trigger tumorous inflammatory response and fuel HCC metastasis. Targeting NETs rather than neutrophils themselves can be a practice strategy against HCC metastasis.

Androgen Receptor (AR)-TLR4 Crosstalk Mediates Gender Disparities in Hepatocellular Carcinoma Incidence and Progression

Background: Androgen receptor (AR) has a role in regulating malignancies and gender disparities in hepatocellular carcinoma (HCC). Recently, TLR4 activation is demonstrated to be required for HCC progression; however, whether and how TLR4 interacts with AR is largely unknown.

Methods: The tumorigenesis was detected in female and male mice induced by DEN/CCL_4, then TLR4 and AR signals were detected in liver tissues by qPCR and FACS. The proliferation, colony formation and migration of HCC cell treated with TLR4 agonist LPS, or/and androgen DHT were evaluated in vitro. Furthermore, the expression of TLR4 and AR was detected by IHC in tissue microarray of HCC, and correlation of AR and TLR4 was defined.

Results: Male mice are more susceptible to develop HCC than female mice. Meanwhile, we found baseline TLR4 levels were higher in male mice than in female mice. AR expression in male mice was increased by treatment with DEN/CCL₄. And, AR was constitutively expressed in human HCC cell lines. Dihydrotestosterone (DHT) stimulated TLR4 expression in both HepG2 and HepG2 2.15 cells, which could be blocked by silencing AR. On the other hand, treatment with LPS stimulated AR expression, but it was blocked by treatment with TLR4 antagonist and in cells deficient for TLR4. DHT treatment exacerbated TLR4-induced cellular proliferation, colony formation, migration, and invasion of HepG2 cells. The positive relationship between AR and TLR4 was confirmed in human HCC samples.

Conclusions: DHT-AR-TLR4 signaling enhances the development of HCC cells and facilitates their migration and invasion, demonstrating a mechanism underlying gender disparity in HCC.

PFKFB3, a key glucose metabolic enzyme regulated by pathogen recognition receptor TLR4 in liver cells

AIMS

Toll-like receptor 4 (TLR4) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB3) are involved in the progress of inflammation and glucose metabolism. Here, we aimed to assess the relationship between TLR4 and PFKFB3 in liver cells.

METHODS

We detected the expression of TLR4 and PFKFB3 in both normal liver cell lines and liver cancer cell lines. Then, a small interfering RNA (siRNA) was used to knock down the expression of TLR4 and analyze the expression of PFKFB3 in the HL-7702 cell line. Further, following stimulation of the HL-7702 cell line with free fatty acids (FFA) or insulin, we observed the expression of TLR4 and PFKFB3, respectively.

RESULTS

Knocking down siRNA-mediated TLR4 significantly reduced PFKFB3 expression at the mRNA and protein level. Furthermore, activating TLR4 with FFA dramatically increased PFKFB3 expression. Insulin increased the expression of TLR4 and PFKFB3, which could be inhibited by TLR siRNA.

CONCLUSION

These findings suggest that PFKFB3 expression is regulated via the TLR4-PFKFB3 axis, which might be a bridge linking fat and glucose metabolism.

Silencing stomatin-like protein 2 attenuates tumor progression and inflammatory response through repressing CD14 in liver cancer

Purpose

Toll-like receptor 4 (TLR4) is involved in the inflammation in liver cancer. High-expressed stomatin-like protein 2 (SLP-2) is commonly reported in many cancer types. This study aims to investigate the functions of SLP-2 in TLR4-mediated inflammatory responses and tumor progression of liver cancer.

Patients and methods

Plasmid transfection technique was applied to silence and overexpress genes. Changes in cell viability and apoptosis were determined by performing cell counting kit-8 assay and flow cytometry. The levels of pro-inflammatory cytokines were determined by ELISA. We further measured the several types of the malignant transformation of SK-Hep1 cells to assess the effects of SLP-2 silencing on the cell migration and invasion, proliferation and angiogenesis of liver cancer in vitro. Western blot and RT-qPCR were performed for expression analysis.

Results

Lipopolysaccharide (LPS) promoted the cell proliferation of SK-Hep1 and production of tumor necrosis factor-α (TNF-α) and IL-6. SLP-2 silencing could inhibit the protein and mRNA levels of CD14 and Cdc42 and subsequently inhibited the levels of TNF-α and IL-6. Overexpressed CD14 not only remarkably reversed the proapoptotic ability of SLP-2 silencing and promoted the expression of Cdc42 and production of TNF-α and IL-6, but also notably reversed the inhibitory effects on the malignant abilities of SK-Hep1 cells by SLP-2 silencing.

Conclusion

SLP-2 silencing could significantly attenuate the inflammatory responses and tumor progression of liver cancer via inhibiting LPS/TLR4 signal transduction through the repression of CD14.

Multiple roles of microRNA-146a in immune responses and hepatocellular carcinoma

MicroRNAs (miRNAs/miRs), consisting of ~22 nucleotides of single-stranded RNA, participate in post-transcriptional gene regulation by binding to the 3′-untranslated region (UTR) of mRNAs, repressing their translation and promoting their degradation. Studies have shown that certain miRNAs play a key role in the control of various cellular activities, such as inhibiting inflammation, modulating cell differentiation and suppressing cancer growth. The role of miR-146a in the immune response and in the pathogenesis of hepatocellular carcinoma (HCC) has also been investigated. Although some studies have shown that increased miR-146a levels are associated with HCC, others have revealed that miR-146a suppresses cancer cell proliferation, invasion and metastasis. Toll-like receptor 4 (TLR4) signaling has an important role in regulating innate and adaptive immune responses. In addition, TLR4 is functionally expressed in HCC cells and promotes HCC cell proliferation, which can be regulated by miR-146a. The present review focuses on the recent progress in analyzing the multiple roles of miR-146a in mediating the TLR4 pathway and adaptive immune response. Finally, the function of miR-146a in the pathogenesis of HCC is also discussed.

The contribution of miR-122 to the innate immunity by regulating toll-like receptor 4 in hepatoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is a kind of malignancies to impact human health. It has been reported that aberrant toll-like receptor (TLR) signaling may contribute to the development and progression of HCC, especially TLR4. MiR-122, which extensively involved in hepatitis virus infection and the apoptosis of hepatoma cells, might be decreased in HCC patients livers. The hypothesis of this study was whether miR-122 plays a role in inflammatory pathways through regulating TLR4 expression in hepatoma cells.

METHODS

The expression of miR-122 in the tissues of HCC patients compared to controls in TCGA datasets was analyzed. The relationship between miR-122 and TLR4 was detected in HCC cell lines by increasing/decreasing miR-122 expression. The target of miR-122 on TLR4 was confirmed by luciferase reporter assays. The proliferation of HCC cells and production of proinflammatory cytokines were measured with miR-122 upregulation and inhibition.

RESULTS

We found that the expression of miR-122 was decreased in HCC tissues and showed the diagnostic capacity for HCC in TCGA datasets. MiR-122 and TLR4 expression have negative correlation in normal liver cells and HCC cells. Upregulation of miR-122 significantly inhibited TLR4 expression in hepatoma cells, including in hepatoma cells with the induction of LPS, while knocking down miR-122 increased TLR4 expression. By screening potential miR-122 targets among TLR4, we found that there was a putative miR-122 target in TLR4 3'UTR. Mutations in the nt1603-nt1609 region of TLR4 3'UTR abandoned the impact of miR-122 on TLR4 expression. Over-expression/down-expression of miR-122 could influence the proliferation and the expression of natural immune factors.

CONCLUSIONS

MiR-122 might target TLR4 and regulate host innate immunity in hepatoma cells, which revealed a new molecular mechanism of miR-122 on the regulation of innate immunity.

Hepatocellular carcinoma: Mechanisms of progression and immunotherapy

Liver cancer is one of the most common malignancies, and various pathogenic factors can lead to its occurrence and development. Among all primary liver cancers, hepatocellular carcinoma (HCC) is the most common. With extensive studies, an increasing number of molecular mechanisms that promote HCC are being discovered. Surgical resection is still the most effective treatment for patients with early HCC. However, early detection and treatment are difficult for most HCC patients, and the postoperative recurrence rate is high, resulting in poor clinical prognosis of HCC. Although immunotherapy takes longer than conventional chemotherapy to produce therapeutic effects, it persists for longer. In recent years, the emergence of many new immunotherapies, such as immune checkpoint blockade and chimeric antigen receptor T cell therapies, has given new hope for the treatment of HCC.

TLR2 Promotes Monocyte/Macrophage Recruitment Into the Liver and Microabscess Formation to Limit the Spread of Listeria Monocytogenes

TLR2 signaling plays a critical protective role against acute Listeria monocytogenes (Lm) infection by up-regulating inflammatory cytokines and promoting macrophage antimicrobial capabilities. However, the underlying mechanism by which TLR2 regulates hepatic macrophage-mediated anti-Lm immune responses remains poorly understood. In this study, we found that both the absolute number and proportion of monocyte/macrophage (Mo/MΦ) in the liver and spleen of Tlr2 ^-/- mice were significantly lower compared to wild type mice. Changes in TLR2 signaling in both hepatocytes and Mo/MΦs were associated with the infiltration of Mo/MΦs in response to Lm-infection. Analyses by proteome profiler array and ELISA revealed that hepatocytes recruited Mo/MΦs via TLR2-dependent secretion of CCL2 and CXCL1, which was confirmed by receptor blocking and exogenous chemokine administration. Importantly, we found that TLR2 contributed to macrophage mobility in the liver through a TLR2/NO/F-actin pathway, facilitating the formation of macrophage-associated hepatic microabscesses. Moreover, TLR2 activation induced the expression of several PRRs on hepatic macrophages associated with the recognition of Lm and augmented macrophage bacterial clearance activity. Our findings provide insight into the intrinsic mechanisms of TLR2-induced Mo/MΦ migration and mobility, as well as the interaction between macrophages and hepatocytes in resistance to Lm infection.

Knockdown of cyclooxygenase-2 leads to growth inhibition and cell cycle arrest in hepatocellular carcinoma cells

Background & aims: Cyclooxygenase-2 (COX-2) is proved to play important roles in the development and progression of various human tumors, including hepatocellular carcinoma (HCC). However, the antitumor effect of RNA interference (RNAi) technology targeting COX-2 in HCC has not yet been verified.

Methods: We silenced COX-2 expression using a lentivirus-mediated RNAi and further investigated the effects of COX-2 knockdown on cell growth and cell cycle in Huh7 and SMMC-7721 cells. COX-2 mRNA was detected by RT-PCR while COX-2 protein was detected by Western blotting. The cell proliferation was measured by MTT assay. The cell cycle was measured by flow cytometry. The tumorigenicity of HCC cells was evaluated using soft-agar clonogenic assay in vitro and nude mouse xenograft model in vivo.

Results: The down-regulation of COX-2 expression significantly inhibited cell proliferation and colony formation, and led to cell cycle arrest in vitro, and reduced the potential of tumorigenicity in vivo in both Huh7 and SMMC-7721 cells. Furthermore, PGE2 production was also decreased after COX-2 expression was suppressed. Finally, knockdown of COX-2 also induced the down-regulation of cell cycle-related protein, cyclinD1.

Conclusions: The abrogation of COX-2 expression can lead to potent antitumor activity and knockdown of COX-2 may be served as a prospective therapeutic strategy against HCC.

AMPK activation inhibits the functions of myeloid-derived suppressor cells (MDSC): impact on cancer and aging

AMP-activated protein kinase (AMPK) has a crucial role not only in the regulation of tissue energy metabolism but it can also control immune responses through its cooperation with immune signaling pathways, thus affecting immunometabolism and the functions of immune cells. It is known that AMPK signaling inhibits the activity of the NF-κB system and thus suppresses pro-inflammatory responses. Interestingly, AMPK activation can inhibit several major immune signaling pathways, e.g., the JAK-STAT, NF-κB, C/EBPβ, CHOP, and HIF-1α pathways, which induce the expansion and activation of myeloid-derived suppressor cells (MDSC). MDSCs induce an immunosuppressive microenvironment in tumors and thus allow the escape of tumor cells from immune surveillance. Chronic inflammation has a key role in the expansion and activation of MDSCs in both tumors and inflammatory disorders. The numbers of MDSCs also significantly increase during the aging process concurrently with the immunosenescence associated with chronic low-grade inflammation. Increased fatty acid oxidation and lactate produced by aerobic glycolysis are important immunometabolic enhancers of MDSC functions. However, it seems that AMPK signaling regulates the functions of MDSCs in a context-dependent manner. Currently, the activators of AMPK signaling are promising drug candidates for cancer therapy and possibly for the extension of healthspan and lifespan. We will describe in detail the AMPK-mediated regulation of the signaling pathways controlling the expansion and activation of immunosuppressive MDSCs. We will propose that the beneficial effects mediated by AMPK activation, e.g., in cancers and the aging process, could be induced by the inhibition of MDSC functions.

Bioanalytical insights into the association between eicosanoids and pathogenesis of hepatocellular carcinoma

It has been noted that inflammatory were intimately associated with the development and progression of hepatocellular carcinoma (HCC). Eicosanoids derived from arachidonic acid play crucial roles in chronic inflammation. Accordingly, there is an intricate relationship between eicosanoids and HCC, being supported by the epidemiological, clinical, and basic science studies. Herein, we intend to provide bioanalytical insights into the role of eicosanoids in HCC progression, from cell proliferation, angiogenesis migration, to apoptosis. Also, the analytical methods and biochemistry of eicosanoids are described.

Circumventing senescence is associated with stem cell properties and metformin sensitivity

Most cancers arise in old individuals, which also accumulate senescent cells. Cellular senescence can be experimentally induced by expression of oncogenes or telomere shortening during serial passage in culture. In vivo, precursor lesions of several cancer types accumulate senescent cells, which are thought to represent a barrier to malignant progression and a response to the aberrant activation of growth signaling pathways by oncogenes (oncogene toxicity). Here, we sought to define gene expression changes associated with cells that bypass senescence induced by oncogenic RAS. In the context of pancreatic ductal adenocarcinoma (PDAC), oncogenic KRAS induces benign pancreatic intraepithelial neoplasias (PanINs), which exhibit features of oncogene‐induced senescence. We found that the bypass of senescence in PanINs leads to malignant PDAC cells characterized by gene signatures of epithelial‐mesenchymal transition, stem cells, and mitochondria. Stem cell properties were similarly acquired in PanIN cells treated with LPS, and in primary fibroblasts and mammary epithelial cells that bypassed Ras‐induced senescence after reduction of ERK signaling. Intriguingly, maintenance of cells that circumvented senescence and acquired stem cell properties was blocked by metformin, an inhibitor of complex I of the electron transport chain or depletion of STAT3, a protein required for mitochondrial functions and stemness. Thus, our studies link bypass of senescence in premalignant lesions to loss of differentiation, acquisition of stemness features, and increased reliance on mitochondrial functions.

Regorafenib reverses HGF-induced sorafenib resistance by inhibiting epithelial-mesenchymal transition in hepatocellular carcinoma

Sorafenib resistance is one of the major obstacles towards achieving a better outcome in patients with advanced hepatocellular carcinoma (HCC), in which aberrant activation of the hepatocyte growth factor (HGF)/mesenchymal‐epithelial transition pathway is frequently observed. Here, we report that HCC cells develop sorafenib resistance following HGF stimulation. Furthermore, HGF activates the downstream extracellular signal‐related kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) pathway and induces epithelial–mesenchymal transition (EMT) by up‐regulating Snail in HCC cells. Inhibition of ERK and STAT3 abolished the rescue effect of HGF by down‐regulating Snail and EMT. Moreover, phosphoinositide 3‐kinase/Akt was also activated in HGF‐treated HCC cells, although it had no effect on Snail expression. Notably, we also found that regorafenib reversed HGF‐induced sorafenib resistance by inhibiting ERK and STAT3, and subsequently down‐regulating Snail and EMT. Taken together, our results indicate that HGF induces sorafenib resistance by activating phosporylated (P)‐ERK/Snail/EMT and P‐STAT3/Snail/EMT pathways. Inhibition of P‐ERK and P‐STAT3 by regorafenib can block HGF‐induced EMT, thereby reversing HGF‐induced sorafenib resistance.