Inhibitory role of peroxisome proliferator-activated receptor gamma in hepatocarcinogenesis in mice and in vitro

Peroxisome proliferator-activated receptors: Key regulators of tumor progression and growth

One of the main causes of death on the globe is cancer. Peroxisome-proliferator-activated receptors (PPARs) are nuclear hormone receptors, including PPARα, PPARδ and PPARγ, which are important in regulating cancer cell proliferation, survival, apoptosis, and tumor growth. Activation of PPARs by endogenous or synthetic compounds regulates tumor progression in various tissues. Although each PPAR isotype suppresses or promotes tumor development depending on the specific tissues or ligands, the mechanism is still unclear. PPARs are receiving interest as possible therapeutic targets for a number of disorders. Numerous clinical studies are being conducted on PPARs as possible therapeutic targets for cancer. Therefore, this review will focus on the existing and future uses of PPARs agonists and antagonists in treating malignancies. PubMed, Science Direct, and Scopus databases were searched regarding the effect of PPARs on various types of cancers until the end of May 2023. The results of the review articles showed the therapeutic influence of PPARs on a wide range of cancer on in vitro, in vivo and clinical studies. However, further experimental and clinical studies are needed to be conducted on the influence of PPARs on various cancers.

Identification of pyroptosis subtypes and prognosis model of hepatocellular carcinoma based on pyroptosis-related genes

BACKGROUND

Hepatocellular carcinoma (HCC) is a common malignant tumor with poor prognosis. Pyroptosis, a type of programmed cell death, regulates tumor cell development. However, the role of pyroptosis-related genes (PRGs) in HCC and their association with prognosis are unclear.

METHODS

We conducted bioinformatics analysis to identify PRGs in The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) patients. Consensus clustering classified patients into different subtypes. We used LASSO regression to established a pyroptosis subtype-related score (PSRS) related to prognosis. OncoPredict identified potential pharmaceuticals based on PSRS.

RESULTS

We found 20 HCC-related PRGs in 335 TCGA-LIHC patients. Consensus clustering classified patients into two subtypes. Subtype I had better overall survival and higher response to anti-PD1 treatment. The prognostic model involving 20 genes predicted poorer prognosis for high-PSRS group. The model was validated in two external cohorts. OncoPredict identified 65 potential pharmaceuticals based on PSRS.

CONCLUSION

Our investigation revealed a correlation between pyroptosis and HCC. We established PSRS as independent risk factors for predicting prognosis. The study paves the way for using PRGs as prognostic biomarkers and exploring personalized therapy for HCC.

GDF15: Immunomodulatory Role in Hepatocellular Carcinoma Pathogenesis and Therapeutic Implications

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths globally and the sixth most common cancer worldwide. Evidence shows that growth differentiation factor 15 (GDF15) contributes to hepatocarcinogenesis through various mechanisms. This paper reviews the latest insights into the role of GDF15 in the development of HCC, its role in the immune microenvironment of HCC, and its molecular mechanisms in metabolic dysfunction associated steatohepatitis (MASH) and metabolic associated fatty liver disease (MAFLD)-related HCC. Additionally, as a serum biomarker for HCC, diagnostic and prognostic value of GDF15 for HCC is summarized. The article elaborates on the immunological effects of GDF15, elucidating its effects on hepatic stellate cells (HSCs), liver fibrosis, as well as its role in HCC metastasis and tumor angiogenesis, and its interactions with anticancer drugs. Based on the impact of GDF15 on the immune response in HCC, future research should identify its signaling pathways, affected immune cells, and tumor microenvironment interactions. Clinical studies correlating GDF15 levels with patient outcomes can aid personalized treatment. Additionally, exploring GDF15-targeted therapies with immunotherapies could improve anti-tumor responses and patient outcomes.

Pirfenidone Reverts Global DNA Hypomethylation, Promoting DNMT1/UHRF/PCNA Coupling Complex in Experimental Hepatocarcinoma

Hepatocellular carcinoma (HCC) development is associated with altered modifications in DNA methylation, changing transcriptional regulation. Emerging evidence indicates that DNA methyltransferase 1 (DNMT1) plays a key role in the carcinogenesis process. This study aimed to investigate how pirfenidone (PFD) modifies this pathway and the effect generated by the association between c-Myc expression and DNMT1 activation. Rats F344 were used for HCC development using 50 mg/kg of diethylnitrosamine (DEN) and 25 mg/kg of 2-Acetylaminofluorene (2-AAF). The HCC/PFD group received simultaneous doses of 300 mg/kg of PFD. All treatments lasted 12 weeks. On the other hand, HepG2 cells were used to evaluate the effects of PFD in restoring DNA methylation in the presence of the inhibitor 5-Aza. Histopathological, biochemical, immunohistochemical, and western blot analysis were carried out and our findings showed that PFD treatment reduced the amount and size of tumors along with decreased Glipican-3, β-catenin, and c-Myc expression in nuclear fractions. Also, this treatment improved lipid metabolism by modulating PPARγ and SREBP1 signaling. Interestingly, PFD augmented DNMT1 and DNMT3a protein expression, which restores global methylation, both in our in vivo and in vitro models. In conclusion, our results suggest that PFD could slow down HCC development by controlling DNA methylation.

Liver cancer development driven by the AP-1/c-Jun~Fra-2 dimer through c-Myc

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death. HCC incidence is on the rise, while treatment options remain limited. Thus, a better understanding of the molecular pathways involved in HCC development has become a priority to guide future therapies. While previous studies implicated the Activator Protein-1 (AP-1) (Fos/Jun) transcription factor family members c-Fos and c-Jun in HCC formation, the contribution of Fos-related antigens (Fra-) 1 and 2 is unknown. Here, we show that hepatocyte-restricted expression of a single chain c-Jun~Fra-2 protein, which functionally mimics the c-Jun/Fra-2 AP-1 dimer, results in spontaneous HCC formation in c-Jun~Fra-2hep mice. Several hallmarks of human HCC, such as cell cycle dysregulation and the expression of HCC markers are observed in liver tumors arising in c-Jun~Fra-2hep mice. Tumorigenesis occurs in the context of mild inflammation, low-grade fibrosis, and Pparγ-driven dyslipidemia. Subsequent analyses revealed increased expression of c-Myc, evidently under direct regulation by AP-1 through a conserved distal 3' enhancer. Importantly, c-Jun~Fra-2-induced tumors revert upon switching off transgene expression, suggesting oncogene addiction to the c-Jun~Fra-2 transgene. Tumors escaping reversion maintained c-Myc and c-Myc target gene expression, likely due to increased c-Fos. Interfering with c-Myc in established tumors using the Bromodomain and Extra-Terminal motif inhibitor JQ-1 diminished liver tumor growth in c-Jun~Fra-2 mutant mice. Thus, our data establish c-Jun~Fra-2hep mice as a model to study liver tumorigenesis and identify the c-Jun/Fra-2-Myc interaction as a potential target to improve HCC patient stratification and/or therapy.

Roles of peroxisome proliferator-activated receptors in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the main pathological type of liver cancer, is linked to risk factors such as viral hepatitis, alcohol intake and non-alcoholic fatty liver disease (NAFLD). Recent advances have greatly improved our understanding that NAFLD is playing a major risk factor for HCC. Peroxisome proliferator-activated receptors (PPARs) are a class of transcription factors divided into three subtypes: PPARα (PPARA), PPARδ/β (PPARD) and PPARγ (PPARG). As important nuclear receptors, PPARs are involved in many physiological processes, and PPARs can improve NAFLD by regulating lipid metabolism, accelerating fatty acid oxidation and inhibiting inflammation. In recent years, some studies have shown that PPARs can participate in the occurrence and development of HCC by regulating metabolic pathways. In addition, PPAR modulators have been reported to inhibit the proliferation and metastasis of HCC cells and can enhance the curative effect of conventional treatments. This article reviews the role of PPARs in the occurrence and development of HCC, as well as its value in the diagnosis, treatment and prognosis of HCC, in order to provide directions for future research.

An Overview of the Role of Peroxisome Proliferator-activated Receptors in Liver Diseases

Peroxisome proliferator-activated receptors (PPARs) are a superfamily of nuclear transcription receptors, consisting of PPARα, PPARγ, and PPARβ/δ, which are highly expressed in the liver. They control and modulate the expression of a large number of genes involved in metabolism and energy homeostasis, oxidative stress, inflammation, and even apoptosis in the liver. Therefore, they have critical roles in the pathophysiology of hepatic diseases. This review provides a general insight into the role of PPARs in liver diseases and some of their agonists in the clinic.

BEX1 supports the stemness of hepatoblastoma by facilitating Warburg effect in a PPARγ/PDK1 dependent manner

BACKGROUND

Hepatoblastoma (HB) is a highly aggressive paediatric malignancy that exhibits a high presence of cancer stem cells (CSCs), which related to tumour recurrence and chemotherapy resistance. Brain expressed X-linked protein 1 (BEX1) plays a pivotal role in ciliogenesis, axon regeneration and differentiation of neural stem cells. However, the role of BEX1 in metabolic and stemness programs in HB remains unclear.

METHODS

BEX1 expression in human and mouse HB was analyzed using gene expression profile data from NCBI GEO and immunohistochemical validation. Seahorse extracellular flux analyzer, ultra-high-performance liquid-chromatography mass spectrometry (LC-MS), flow cytometry, qRT-PCR, Western Blot, sphere formation assay, and diluted xenograft tumour formation assay were used to analyze metabolic and stemness features.

RESULTS

Our results indicated that overexpression of BEX1 significantly enhanced the Warburg effect in HB cells. Furthermore, glycolysis inhibition largely attenuated the effects of BEX1 on HB cell growth and self-renewal, suggesting that BEX1 promotes stemness maintenance of HB cells by regulating the Warburg effect. Mechanistically, BEX1 enhances Warburg effect through the downregulation of peroxisome proliferator-activated receptor-gamma (PPARγ). Furthermore, pyruvate dehydrogenase kinase isozyme 1 (PDK1) is required for PPARγ-induced inhibition of Warburg effect in HB. In addition, BEX1 supports the stemness of HB by enhancing Warburg effect in a PPARγ/PDK1 dependent manner.

CONCLUSIONS

HB patients with high BEX1 and PDK1 expression had a poor prognosis. BEX1 promotes the stemness maintenance of HB cells via modulating the Warburg effect, which depends on PPARγ/PDK1 axis. Pioglitazone could be used to target BEX1-mediated stemness properties in HB by upregulating PPARγ.

Targeting PPAR-gamma counteracts tumour adaptation to immune-checkpoint blockade in hepatocellular carcinoma

OBJECTIVE

Therapy-induced tumour microenvironment (TME) remodelling poses a major hurdle for cancer cure. As the majority of patients with hepatocellular carcinoma (HCC) exhibits primary or acquired resistance to antiprogrammed cell death (ligand)-1 (anti-PD-[L]1) therapies, we aimed to investigate the mechanisms underlying tumour adaptation to immune-checkpoint targeting.

DESIGN

Two immunotherapy-resistant HCC models were generated by serial orthotopic implantation of HCC cells through anti-PD-L1-treated syngeneic, immunocompetent mice and interrogated by single-cell RNA sequencing (scRNA-seq), genomic and immune profiling. Key signalling pathway was investigated by lentiviral-mediated knockdown and pharmacological inhibition, and further verified by scRNA-seq analysis of HCC tumour biopsies from a phase II trial of pembrolizumab (NCT03419481).

RESULTS

Anti-PD-L1-resistant tumours grew >10-fold larger than parental tumours in immunocompetent but not immunocompromised mice without overt genetic changes, which were accompanied by intratumoral accumulation of myeloid-derived suppressor cells (MDSC), cytotoxic to exhausted CD8+ T cell conversion and exclusion. Mechanistically, tumour cell-intrinsic upregulation of peroxisome proliferator-activated receptor-gamma (PPARγ) transcriptionally activated vascular endothelial growth factor-A (VEGF-A) production to drive MDSC expansion and CD8+ T cell dysfunction. A selective PPARγ antagonist triggered an immune suppressive-to-stimulatory TME conversion and resensitised tumours to anti-PD-L1 therapy in orthotopic and spontaneous HCC models. Importantly, 40% (6/15) of patients with HCC resistant to pembrolizumab exhibited tumorous PPARγ induction. Moreover, higher baseline PPARγ expression was associated with poorer survival of anti-PD-(L)1-treated patients in multiple cancer types.

CONCLUSION

We uncover an adaptive transcriptional programme by which tumour cells evade immune-checkpoint targeting via PPARγ/VEGF-A-mediated TME immunosuppression, thus providing a strategy for counteracting immunotherapeutic resistance in HCC.

Non-alcoholic fatty liver disease and diabetes mellitus as growing aetiologies of hepatocellular carcinoma

Obesity-related complications such as non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D) are well-established risk factors for the development of hepatocellular carcinoma (HCC). This review provides insights into the molecular mechanisms that underlie the role of steatosis, hyperinsulinemia and hepatic inflammation in HCC development and progression. We focus on recent findings linking intracellular pathways and transcription factors that can trigger the reprogramming of hepatic cells. In addition, we highlight the role of enzymes in dysregulated metabolic activity and consequent dysfunctional signalling. Finally, we discuss the potential uses and challenges of novel therapeutic strategies to prevent and treat NAFLD/T2D-associated HCC.

The endocannabinoid system, a new gatekeeper in the pharmacology of human hepatocellular carcinoma

Despite numerous prevention methodologies and treatment options, hepatocellular carcinoma (HCC) still remains as the third leading life-threatening cancer. It is thus pertinent to develop new treatment modality to fight this devastating carcinoma. Ample recent studies have shown the anti-inflammatory and antitumor roles of the endocannabinoid system in various forms of cancers. Preclinical studies have also confirmed that cannabinoid therapy can be an optimal regimen for cancer treatments. The endocannabinoid system is involved in many cancer-related processes, including induction of endoplasmic reticulum (ER) stress-dependent apoptosis, autophagy, PITRK and ERK signaling pathways, cell invasion, epithelial-mesenchymal transition (EMT), and cancer stem cell (CSC) phenotypes. Moreover, changes in signaling transduction of the endocannabinoid system can be a potential diagnostic and prognostic biomarker for HCC. Due to its pivotal role in lipid metabolism, the endocannabinoid system affects metabolic reprogramming as well as lipid content of exosomes. In addition, due to the importance of non-coding RNAs (ncRNAs), several studies have examined the relationship between microRNAs and the endocannabinoid system in HCC. However, HCC is a pathological condition with high heterogeneity, and therefore using the endocannabinoid system for treatment has faced many controversies. While some studies favored a role of the endocannabinoid system in carcinogenesis and tumor induction, others exhibited the anticancer potential of endocannabinoids in HCC. In this review, specific studies delineating the relationship between endocannabinoids and HCC are examined. Based on collected findings, detailed studies of the molecular mechanism of endocannabinoids as well as preclinical studies for investigating therapeutic or carcinogenic impacts in HCC cancer are strongly suggested.

Good or bad: Paradox of plasminogen activator inhibitor 1 (PAI-1) in digestive system tumors

The fibrinolytic system is involved in many physiological functions, among which the important members can interact with each other, either synergistically or antagonistically to participate in the pathogenesis of many diseases. Plasminogen activator inhibitor 1 (PAI-1) acts as a crucial element of the fibrinolytic system and functions in an anti-fibrinolytic manner in the normal coagulation process. It inhibits plasminogen activator, and affects the relationship between cells and extracellular matrix. PAI-1 not only involved in blood diseases, inflammation, obesity and metabolic syndrome but also in tumor pathology. Especially PAI-1 plays a different role in different digestive tumors as an oncogene or cancer suppressor, even a dual role for the same cancer. We term this phenomenon "PAI-1 paradox". PAI-1 is acknowledged to have both uPA-dependent and -independent effects, and its different actions can result in both beneficial and adverse consequences. Therefore, this review will elaborate on PAI-1 structure, the dual value of PAI-1 in different digestive system tumors, gene polymorphisms, the uPA-dependent and -independent mechanisms of regulatory networks, and the drugs targeted by PAI-1 to deepen the comprehensive understanding of PAI-1 in digestive system tumors.

Impending Chemotherapeutic Impact of Arthrospira platensis Nanoparticles and/or Sorafenib against Hepatocellular Carcinoma through Modulation of Antioxidant Status, Tumor Marker Genes, and Anti-Inflammatory Signaling Pathways

This study investigated Arthrospira platensis nanoparticles (NSP) to overcome sorafenib resistance in diethyl nitrosamine-induced hepatocellular carcinoma (HCC) in rats. This study used sixty Wistar male rats randomly grouped into two main groups, the normal control group, and the HCC model. For the normal control group (n = 12), animals were injected i.p. with PBS two times/week for 16 weeks. The remaining 48 rats were injected i.p. with using a single dose of diethyl nitrosamine (DENA) (200 mg/kg, ip), followed by phenobarbital sodium (0.05%) in drinking water for 16 weeks. At the end of the 16th week, rats were allocated into four groups (11 rats/each), one group was left without treatment (DENA group), and the other three groups were treated with either sorafenib (30 mg/kg; p.o.) or Arthrospira platensis Nanoparticles (NSP) (0.5 mg/kg body weight) once daily orally with the aid of gastric gavage or their combination for another four weeks. Blood and tissue samples were collected for further biochemical, histological, immunohistochemical, and gene expression analysis. Our result revealed that DENA-treated rats showed a marked elevation of hepatic enzyme markers with an increase in the total protein and globulin and decreases in the hepatic SOD. Catalase and GSH, with significantly increased MDA levels, subsequently increased the tumor biomarkers (AFP and CEA). On the molecular level, the DENA-treated rats showed significant up-regulation of Cyp19 mRNA and the inflammatory cytokines (TNF-α, iNOS, and TGF-1β) as well as the Ki-67 gene expression (p < 0.05) with down-regulation of the PPAR-γ and FOXO-1. In addition, the HCC group showed a loss of hepatic architecture, as well as atypia, swelling, macrosteatosis of hepatocytes, and fibrosis, besides increased vascularization. The immunohistochemical findings show increased expression of both GPC-3 and Hep Par 1 in the HCC group. SOR, NSP, or a combination of NSP and SOR.NSP treatment significantly overturned the DENA's harmful effect near the normal levels and restored all cancer biomarkers and antioxidant activities, indicating the chemotherapeutic impact of NSP. The present study provides evidence that NSP exerts a major anticancer effect on DENA-induced HCC. SOR/NSP is a promising combination for tumor suppression and overcoming sorafenib resistance in HCC by modulating antioxidants, anti-inflammatory signals, and tumor markers.

Is the peroxisome proliferator-activated receptor gamma a putative target for epilepsy treatment? Current evidence and future perspectives

The peroxisome proliferator-activated receptor gamma (PPARγ), which belongs to the family of nuclear receptors, has been mainly studied as an important factor in metabolic disorders. However, in recent years the potential role of PPARγ in different neurological diseases has been increasingly investigated. Especially, in the search of therapeutic targets for patients with epilepsy the question of the involvement of PPARγ in seizure control has been raised. Epilepsy is a chronic neurological disorder causing a major impact on the psychological, social, and economic conditions of patients and their families, besides the problems of the disease itself. Considering that the world prevalence of epilepsy ranges between 0.5% - 1.0%, this condition is the fourth for importance among the other neurological disorders, following migraine, stroke, and dementia. Among others, temporal lobe epilepsy (TLE) is the most common form of epilepsy in adult patients. About 65% of individuals who receive antiseizure medications (ASMs) experience seizure independence. For those in whom seizures still recur, investigating PPARγ could lead to the development of novel ASMs. This review focuses on the most important findings from recent investigations about the potential intracellular PPARγ-dependent processes behind different compounds that exhibited anti-seizure effects. Additionally, recent clinical investigations are discussed along with the promising results found for PPARγ agonists and the ketogenic diet (KD) in various rodent models of epilepsy.

Fuzheng Xiaozheng prescription exerts anti-hepatocellular carcinoma effects by improving lipid and glucose metabolisms via regulating circRNA-miRNA-mRNA networks

BACKGROUND

Hepatocellular carcinoma (HCC) is a major threat to human health due to its high lethality. Our previous studies suggested that Fuzheng Xiaozheng prescription (FZXZP), an effective Chinese medicine, demonstrated significant suppressive effects on HCC. However, its underlying mechanism remains largely unclear.

PURPOSE

This study aimed to investigate the anti-HCC mechanisms of FZXZP from transcriptomic sequencing based on a holistic perspective.

METHODS

Rat HCC model was induced by diethylnitrosamine, and then the model was administered with two doses of FZXZP, high and low. Sodium demethylcantharidate was used as a positive control. Subsequently, microarrays of circRNA, miRNA and mRNA were performed on the blank, model, high and low dose groups, respectively, and the competitive binding mechanisms among them were further analyzed by bioinformatics. Then, the circRNA-miRNA-mRNA networks were constructed to mine the targeted-RNAs of FZXZP in HCC, as well as to explore their potential regulatory mechanisms. Finally, functions and pathways of the FZXZP targeted genes in rat HCC were annotated with GO and KEGG, and qRT-PCR was performed to validate the accuracy of the above analyses in this study.

RESULTS

The results showed that FZXZP significantly inhibited the development and progression of HCC in rats, improved the pathological conditions and suppressed the proliferation of HCC cells. Subsequently, after a series of screening, the competing endogenous RNA networks (circRNA-miRNA-mRNA), consisting of 2 circRNAs, 7 miRNAs and 104 mRNAs, were finally established. KEGG and GO analyses of the networks revealed that lipid metabolism related pathways, such as fatty acid metabolism, bile secretion and PPAR pathway, were significantly enriched. In the further hubgene network analysis, in addition to lipid metabolism, aberrant glucose metabolism was found to be ameliorated by G6pc and Pklr in hubgenes. Finally, the qRT-PCR analyses confirmed that the expression tendencies of the above targeted genes were correct and believable in transcriptomic sequencings, and qRT-PCR results of the genes closely related to proliferation, invasion and apoptosis of HCC also indicated the inhibitory effects of FZXZP on HCC obviously.

CONCLUSION

FZXZP demonstrated significant anti-HCC effects through improving lipid and glucose metabolism, restoring the metabolic homeostasis of the liver via circRNA-miRNA-mRNA networks.

Peroxisome proliferator-activated receptor gamma as a therapeutic target for hepatocellular carcinoma: Experimental and clinical scenarios

Hepatocellular carcinoma (HCC) is the most common type of liver cancer worldwide. Viral hepatitis is a significant risk factor for HCC, although metabolic syndrome and diabetes are more frequently associated with the HCC. With increasing prevalence, there is expected to be > 1 million cases annually by 2025. Therefore, there is an urgent need to establish potential therapeutic targets to cure this disease. Peroxisome-proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that plays a crucial role in the patho-physiology of HCC. Many synthetic agonists of PPARγ suppress HCC in experimental studies and clinical trials. These synthetic agonists have shown promising results by inducing cell cycle arrest and apoptosis in HCC cells and preventing the invasion and metastasis of HCC. However, some synthetic agonists also pose severe side effects in addition to their therapeutic efficacy. Thus natural PPARγ agonists can be an alternative to exploit this potential target for HCC treatment. In this review, the regulatory role of PPARγ in the pathogenesis of HCC is elucidated. Furthermore, the experimental and clinical scenario of both synthetic and natural PPARγ agonists against HCC is discussed. Most of the available literature advocates PPARγ as a potential therapeutic target for the treatment of HCC.

Oroxylin A inhibits the migration of hepatocellular carcinoma cells by inducing NAG-1 expression

Hepatocellular carcinoma (HCC), the most prevalent liver cancer, is considered one of the most lethal malignancies with a dismal outcome mainly due to frequent intrahepatic and distant metastasis. In the present study, we demonstrated that oroxylin A, a natural product extracted from Scutellaria radix, significantly inhibits transforming growth factor-beta1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) and metastasis in HCC. Oroxylin A blocked the TGF-β1/Smad signaling via upregulating the non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) expression. Oroxylin A promoted NAG-1 transcription by regulating the acetylation of CCAAT/enhancer binding protein β (C/EBPβ), a transcription factor that binds to the NAG-1 promoter. In terms of the underlying mechanism, oroxylin A may interact with histone deacetylase 1 (HDAC1) by forming hydrogen bonds with GLY149 residue and induce proteasome-mediated degradation of HDAC1 subsequently impairing HDAC1-mediated deacetylation of C/EBPβ and promoting the expression of NAG-1. Taken together, our findings revealed a previously unknown tumor-suppressive mechanism of oroxylin A. Oroxylin A should be further investigated as a potential clinical candidate for inhibiting HCC metastasis.

A growth factor-expressing macrophage subpopulation orchestrates regenerative inflammation via GDF-15

Muscle regeneration is the result of the concerted action of multiple cell types driven by the temporarily controlled phenotype switches of infiltrating monocyte-derived macrophages. Pro-inflammatory macrophages transition into a phenotype that drives tissue repair through the production of effectors such as growth factors. This orchestrated sequence of regenerative inflammatory events, which we termed regeneration-promoting program (RPP), is essential for proper repair. However, it is not well understood how specialized repair-macrophage identity develops in the RPP at the transcriptional level and how induced macrophage-derived factors coordinate tissue repair. Gene expression kinetics-based clustering of blood circulating Ly6Chigh, infiltrating inflammatory Ly6Chigh, and reparative Ly6Clow macrophages, isolated from injured muscle, identified the TGF-β superfamily member, GDF-15, as a component of the RPP. Myeloid GDF-15 is required for proper muscle regeneration following acute sterile injury, as revealed by gain- and loss-of-function studies. Mechanistically, GDF-15 acts both on proliferating myoblasts and on muscle-infiltrating myeloid cells. Epigenomic analyses of upstream regulators of Gdf15 expression identified that it is under the control of nuclear receptors RXR/PPARγ. Finally, immune single-cell RNA-seq profiling revealed that Gdf15 is coexpressed with other known muscle regeneration-associated growth factors, and their expression is limited to a unique subpopulation of repair-type macrophages (growth factor-expressing macrophages [GFEMs]).

Metronidazole enhances steatosis-related early-stage hepatocarcinogenesis in high fat diet-fed rats through DNA double-strand breaks and modulation of autophagy

Nonalcoholic fatty liver disease is a hepatic disorder with deposition of fat droplets and has a high risk of progression to steatosis-related hepatitis and irreversible hepatic cancer. Metronidazole (MNZ) is an antiprotozoal and antimicrobial agent widely used to treat patients infected with anaerobic bacteria and intestinal parasites; however, MNZ has also been shown to induce liver tumors in rodents. To investigate the effects of MNZ on steatosis-related early-stage hepatocarcinogenesis, male rats treated with N-nitrosodiethylamine following 2/3 hepatectomy at week 3 were received a control basal diet, high fat diet (HFD), or HFD containing 0.5% MNZ. The HFD induced obesity and steatosis in the liver, accompanied by altered expression of Pparg and Fasn, genes related to lipid metabolism. MNZ increased nuclear translocation of lipid metabolism-related transcription factor peroxisome proliferator-activated receptor gamma in hepatocytes, together with altered liver expression of lipid metabolism genes (Srebf1, Srebf2, Pnpla2). Furthermore, MNZ significantly increased the number of preneoplastic liver foci, accompanied by DNA double-strand breaks and late-stage autophagy inhibition, as reflected by increased levels of γ-H2AX, LC3, and p62. Therefore, MNZ could induce steatosis-related hepatocarcinogenesis by inducing DNA double-strand breaks and modulating autophagy in HFD-fed rats.

PPARs as Metabolic Sensors and Therapeutic Targets in Liver Diseases

Carbohydrates and lipids are two components of the diet that provide the necessary energy to carry out various physiological processes to help maintain homeostasis in the body. However, when the metabolism of both biomolecules is altered, development of various liver diseases takes place; such as metabolic-associated fatty liver diseases (MAFLD), hepatitis B and C virus infections, alcoholic liver disease (ALD), and in more severe cases, hepatocelular carcinoma (HCC). On the other hand, PPARs are a family of ligand-dependent transcription factors with an important role in the regulation of metabolic processes to hepatic level as well as in other organs. After interaction with specific ligands, PPARs are translocated to the nucleus, undergoing structural changes to regulate gene transcription involved in lipid metabolism, adipogenesis, inflammation and metabolic homeostasis. This review aims to provide updated data about PPARs’ critical role in liver metabolic regulation, and their involvement triggering the genesis of several liver diseases. Information is provided about their molecular characteristics, cell signal pathways, and the main pharmacological therapies that modulate their function, currently engaged in the clinic scenario, or in pharmacological development.

Upregulated PPARG2 facilitates interaction with demethylated AKAP12 gene promoter and suppresses proliferation in prostate cancer

Prostate cancer (PCA) is one of the most common male genitourinary tumors. However, the molecular mechanisms involved in the occurrence and progression of PCA have not been fully clarified. The present study aimed to investigate the biological function and molecular mechanism of the nuclear receptor peroxisome proliferator-activated receptor gamma 2 (PPARG2) in PCA. Our results revealed that PPARG2 was downregulated in PCA, and overexpression of PPARG2 inhibited cell migration, colony formation, invasion and induced cell cycle arrest of PCA cells in vitro. In addition, PPARG2 overexpression modulated the activation of the Akt signaling pathway, as well as inhibited tumor growth in vivo. Moreover, mechanistic analysis revealed that PPARG2 overexpression induced increased expression level of miR-200b-3p, which targeted 3′ UTR of the downstream targets DNMT3A/3B, and facilitated interaction with demethylated AKAP12 gene promoter and suppressed cell proliferation in PCA. Our findings provided the first evidence for a novel PPARG2-AKAP12 axis mediated epigenetic regulatory network. The study identified a molecular mechanism involving an epigenetic modification that could be possibly targeted as an antitumoral strategy against prostate cancer.

C/EBPα Regulates FOXC1 to Modulate Tumor Growth by Interacting with PPARγ in Hepatocellular Carcinoma

BACKGROUND

Forkhead box C1 (FOXC1) is an important cancer-associated gene in tumor. PPAR-γ and C/EBPα are both transcriptional regulators involved in tumor development.

OBJECTIVE

We aimed to clarify the function of PPAR-γ, C/EBPα in hepatocellular carcinoma (HCC) and the relationship of PPAR-γ, C/EBPα and FOXC1 in HCC.

METHODS

Western blotting, immunofluorescent staining, and immunohistochemistry were used to evaluate protein expression. qRT-PCR was used to assess mRNA expression. Co-IP was performed to detect the protein interaction. And ChIP and fluorescent reporter detection were used to determine the binding between protein and FOXC1 promoter.

RESULTS

C/EBPα could bind to FOXC1 promoter and PPAR-γ could strengthen C/EBPα's function. Expressions of C/EBPα and PPAR-γ were both negatively related to FOXC1 in human HCC tissue. Confocal displayed that C/EBPα was co-located with FOXC1 in HepG2 cells. C/EBPα could bind to FOXC1 promoter by ChIP. Luciferase activity detection exhibited that C/EBPα could inhibit FOXC1 promoter activity, especially FOXC1 promoter from -600 to -300 was the critical binding site. Only PPAR-γ could not influence luciferase activity but strengthen inhibited effect of C/EBPα. Further, the Co-IP displayed that PPAR-γ could bind to C/EBPα. When C/EBPα and PPAR-γ were both high expressed, cell proliferation, migration, invasion, and colony information were inhibited enormously. C/EBPα plasmid combined with or without PPAR-γ agonist MDG548 treatment exhibited a strong tumor inhibition and FOXC1 suppression in mice.

CONCLUSION

Our data establish C/EBPα targeting FOXC1 as a potential determinant in the HCC, which supplies a new pathway to treat HCC. However, PPAR-γ has no effect on FOXC1 expression.

The herbal agent plantamajoside, exerts a potential inhibitory effect on the development of hepatocellular carcinoma

Plantamajoside (PMS), a major component of Plantago asiatica L, has several pharmacological properties, including anti-proliferative, anti-inflammatory and anti-tumor effects. However, the effects of PMS on hepatocellular carcinoma (HCC) have yet to be determined. The aim of the present study was to investigate the effects of PMS on HCC and elucidate the underlying mechanism. All assays were conducted using 5 groups, namely control, sorafenib, and PMS 100, 50, and 25 µg/ml groups. Cell proliferation was determined by the MTT assay. Cell migration was evaluated with the wound healing and Transwell assays, respectively. Cell apoptosis and cell cycle distribution were evaluated via flow cytometry. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis and western blotting were used to further investigate the mechanism of action of PMS. Sorafenib and PMS both significantly attenuated the proliferation and migration of HCC cells, and markedly promoted cell apoptosis. PMS induced cell cycle arrest in the G0/G1 phase. The efficacy of PMS increased in a dose-dependent manner. Further study evaluated the expression of peroxisome proliferator-activated receptor (PPARγ), nuclear factor (NF)-κB and cyclooxygenase (Cox-2) using RT-qPCR analysis and western blotting. The results demonstrated that PMS promoted the expression of PPARγ and suppressed the expression of NF-κB and Cox-2. In conclusion, PMS was shown to affect cell proliferation, migration, apoptosis and cell cycle distribution. Furthermore, PMS promoted the expression of PPARγ and inhibited the expression of NF-κB and Cox-2, which may be the mechanism underlying its biological effects. Based on the results of the present study, PMS appears to be a promising agent for HCC therapy.

A nomogram combining PPARγ expression profiles and clinical factors predicts survival in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with poor prognosis. Peroxisome proliferator-activated receptor γ (PPARγ) is involved in the development of various tumor types. However, its role in hepatocellular carcinoma (HCC) remains unclear. Multiple databases including The Cancer Genome Atlas, Gene Expression Omnibus and Kaplan-Meier plotter were used for bioinformatics analysis of the PPARγ gene or protein. Immunohistochemical labeling of tumor and adjacent normal tissues obtained from 125 patients with HCC was performed to analyze the relationship between PPARγ expression and overall survival (OS) rate. PPARγ was evaluated using functional enrichment analyses and Lasso regression was used to conduct a dimensionality reduction analysis of 43 clinical factors for HCC. An OS prognostic nomogram was then established using seven independent risk factors screened via Lasso regression. PPARγ expression in HCC tumor tissues was higher compared with that in normal liver tissues, and its high expression was associated with poor prognosis, as indicated by bioinformatics analysis. However, opposite results were obtained using the clinical specimens. Functional enrichment analysis indicated that PPARγ was enriched in the 'fatty acid metabolism' pathway. Lasso regression identified seven clinical factors associated with prognosis, including Tumor-Node-Metastasis stage, grade, vascular invasion, α fetoprotein, carbohydrate antigen 199, γ-glutamyl transpeptidase and the PPARγ protein. These seven clinical factors were to construct an OS prognostic nomogram. Overall, PPARγ was highly expressed in the livers of patients with HCC and can be included in an OS prognostic nomogram. However, the factors underlying the differential association of PPARγ expression with HCC prognosis in different datasets should be further investigated.

ZBTB20 regulates WNT/CTNNB1 signalling pathway by suppressing PPARG during hepatocellular carcinoma tumourigenesis

Background & Aims

Zinc finger and BTB domain containing 20 (ZBTB20) has been implicated as a potential oncogene in liver cancer. However, knockout studies have shown it to be a transcriptional repressor of the alpha-foetoprotein (Afp) gene in adult liver, and reduced levels of ZBTB20 allow for upregulation of AFP with increased tumour severity in certain cases of hepatocellular carcinoma (HCC). As there are many discrepancies in the literature regarding its role in liver tumourigenesis, the aim of this study was to elucidate the role of ZBTB20 in HCC tumourigenesis.

Methods

A reverse genetic study using the Sleeping Beauty (SB) transposon system in mice was performed to elucidate the role of ZBTB20 in HCC tumourigenesis. In vitro ZBTB20 gain- and loss-of-function experiments were used to assess the relationship amongst ZBTB20, peroxisome proliferator activated receptor gamma (PPARG) and catenin beta 1 (CTNNB1).

Results

Transgenic overexpression of ZBTB20 in hepatocytes and in the context of transformation related protein (T r p53) inactivation induced hepatic hypertrophy, activation of WNT/CTNNB1 signalling, and development of liver tumours. In vitro overexpression and knockout experiments using CRISPR/Cas9 demonstrated the important role for ZBTB20 in downregulating PPARG, resulting in activation of the WNT/CTNNB1 signalling pathway and its downstream effectors in HCC tumourigenesis.

Conclusions

These findings demonstrate a novel interaction between ZBTB20 and PPARG, which leads to activation of the WNT/CTNNB1 signalling pathway in HCC tumourigenesis.

Lay summary

ZBTB20 has been implicated as a potential oncogene in liver cancer. Herein, we uncover its important role in liver cancer development. We show that it interacts with PPARG to upregulate the WNT/CTNNB1 signalling pathway, leading to tumourigenesis.

Gut Microbiota, Peroxisome Proliferator-Activated Receptors, and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. HCC incidence rate is sixth and mortality is fourth worldwide. However, HCC pathogenesis and molecular mechanisms remain unclear. The incidence of HCC is associated with genetic, environmental, and metabolic factors. The role of gut microbiota in the pathogenesis of HCC has attracted researchers’ attention because of anatomical and functional interactions between liver and intestine. Studies have demonstrated the involvement of gut microbiota in the development of HCC and chronic liver diseases, such as alcoholic liver disease (ALD), nonalcoholic fatty liver disease (NAFLD), and liver cirrhosis. Peroxisome proliferator-activated receptors (PPARs) are a group of receptors with diverse biological functions. Natural and synthetic PPAR agonists show potential for treatment of NAFLD, liver fibrosis, and HCC. Recent studies have demonstrated that PPARs take part in gut microbiota inhabitation and adaptation. This manuscript reviews the role of gut microbiota in the development of HCC and precancerous diseases, the role of PPARs in modulation of gut microbiota and HCC, and potential of gut microbiota for HCC diagnosis and treatment.

The potential chemotherapeutic effect of β-ionone and/or sorafenib against hepatocellular carcinoma via its antioxidant effect, PPAR-γ, FOXO-1, Ki-67, Bax, and Bcl-2 signaling pathways

Proliferation and apoptosis are two primary driving forces behind the pathogenesis of hepatocellular carcinoma (HCC). HCC is associated with Ki-67 and Bcl-2 overexpression, reduced Bax expression inducing disturbance of equilibrium between cellular proliferation and apoptosis, and exacerbated by reduced expression of PPAR-γ and FOXO-1. Our objective was to examine the mechanism by which the cyclic isoprenoid, β-ionone (βI), attenuated hepatocarcinogenesis and compare its possible anticancer activity with sorafenib (SF) as standard HCC treatment. HCC induction was achieved by supplying Wistar rats with 0.01% diethylnitrosamine (DENA) for 8 consecutive weeks by free access of drinking water. The effects of βI (160 mg/kg/day) administered orally were evaluated by biochemical, oxidative stress, macroscopical, and histopathological analysis. In addition, immunohistochemical assay for localization and expression of Bax and Bcl-2 and RT-PCR for expression levels of PPAR-γ, FOXO-1, and Ki-67 mRNA were performed. βI treatment significantly reduced the incidence, total number, and multiplicity of visible hepatocyte nodules, attenuated LPO, near-normal restoration of all cancer biomarkers, and antioxidant activities, indicating the chemotherapeutic impact of βI. Histopathological analysis of the liver confirmed that further. βI also induced pro-apoptotic protein Bax expression and reduced anti-apoptotic expression of Bcl-2 protein. Moreover, βI induced mRNA expression of tumor suppressor genes (PPAR-γ and FOXO-1) and decreased proliferative marker Ki-67 mRNA expression. For the first time, the present study provides evidence that βI exerts a major anticancer effect on DENA-induced HCC, at least in part, through inhibition of cell proliferation, oxidative stress, and apoptogenic signal induction mediated by downregulation of Bcl-2 and upregulation of Bax, PPAR-γ, and FOXO-1 expressions.

Dysregulation of miR484-TUSC5 axis takes part in the progression of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. miR-484 is previously reported to be a crucial modulator during the process from precancerous lesion to cancer. Tumour suppressor candidate 5 (TUSC5) is a potential tumour suppressor, but its expression and function in HCC are obscure. In this study, we aimed to explore the roles of miR-484 and TUSC5 in HCC, and clarify the relationship between them. We demonstrated that miR-484 was significantly up-regulated in HCC, while TUSC5 was down-regulated. TUSC5 was validated as the target gene of miR-484 and both of them were associated with the prognosis of HCC patients. miR-484 mimics markedly promoted the malignant phenotypes while TUSC5 plasmid had the opposite effect. In conclusion, miR-484/TUSC5 is potential diagnostic biomarkers and therapy targets for HCC.

STAT gene family mRNA expression and prognostic value in hepatocellular carcinoma

Background

Signal transducer and activator of transcription (STAT) proteins are well-known transcription factors that play an important role in the progression of cancer. However, the association between STAT family genes and hepatocellular carcinoma (HCC) remains unclear. This study investigates the expression level, the prognostic value and the potential mechanism of STAT family genes in HCC.

Methods

Data from 365 HCC patients in The Cancer Genome Atlas (TCGA) database and 241 HCC patients in the Gene Expression Omnibus (GEO) database were used to investigate the diagnostic and prognostic values of STAT genes by survival analysis and nomogram. Gene set enrichment analysis (GSEA) was used to investigate the potential mechanism of the STAT genes in the development of HCC.

Results

Our results showed that STAT4/5B mRNA expression levels in HCC tissues were lower than those in normal tissues. Importantly, our results indicated that high expression of STAT5A, STAT5B and STAT6 was associated with better overall survival in HCC patients. Joint effects analysis of STAT5A, STAT5B and STAT6 suggested that the prognosis difference for any combination of genes was more significant than that for any individual gene. Then, we developed a risk score model could predict HCC prognosis and the nomogram visualized gene expression and clinical factors of probability for HCC prognosis. The ROC and calibration curves showed good performance in survival prediction in both the TCGA and the GEO databases. GSEA suggested that high expression of STAT5A, STAT5B and STAT6 were involved in immune-related biological processes, drug metabolism cytochrome P450, JAK-STAT signalling pathway, and PPAR signalling pathways.

Conclusion

Our data suggest that STAT5A, STAT5B and STAT6 expression may be potential prognostic markers of HCC and, in combination, have a better predictive value for HCC prognosis.

Avicularin ameliorates human hepatocellular carcinoma via the regulation of NF‑κB/COX‑2/PPAR‑γ activities

Hepatocellular carcinoma (HCC) has become a global public health problem. Therefore, the development of novel and effective therapeutic agents for the treatment of HCC is considered an emergency. Avicularin, a bio-active flavonoid from plants, has been reported to exhibit diverse pharmacological properties. The aim of the present study was to investigate the role of avicularin in HCC and the underlying mechanism of action. Huh7 cells were treated with avicularin in a concentration-dependent manner, and the cell proliferation was examined using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay kit. The cell migration and invasion abilities were detected using wounding-healing assays and Transwell assays. Flow cytometric analysis was performed to investigate the cell cycle distribution and cell apoptosis. The activity of nuclear factor (NF)-κB (p65), cyclooxygenase-2 (COX-2) and peroxisome proliferator-activated receptor γ (PPAR-γ) were measured by reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. The results indicated that avicularin treatment markedly decreased cell proliferation concentration-dependently in HCC, and inhibited cell migration and invasion in Huh7 cells. It was also found that the treatment of avicularin markedly inhibited the G0/G1-phase cells and decreased the accumulation of S-phase cells in the cell cycle and induced cell apoptosis. In addition, it was confirmed that the anticancer efficacy of avicularin in HCC was dependent on the regulation of NF-κB (p65), COX-2 and PPAR-γ activities. In conclusion, the findings suggested that avicularin serves an antineoplastic role in HCC and may provide a potential therapeutic strategy for the treatment of HCC.

Programming of macrophages by UV-irradiated apoptotic cancer cells inhibits cancer progression and lung metastasis

Apoptotic cell clearance by phagocytes is essential in tissue homeostasis. We demonstrated that conditioned medium (CM) from macrophages exposed to apoptotic cancer cells inhibits the TGFβ1-induced epithelial–mesenchymal transition (EMT), migration, and invasion of cancer cells. Apoptotic 344SQ (ApoSQ) cell-induced PPARγ activity in macrophages increased the levels of PTEN, which was secreted in exosomes. Exosomal PTEN was taken up by recipient lung cancer cells. ApoSQ-exposed CM from PTEN knockdown cells failed to enhance PTEN in 344SQ cells, restore cellular polarity, or exert anti-EMT and anti-invasive effects. The CM that was deficient in PPARγ ligands, including 15-HETE, lipoxin A4, and 15d-PGJ₂, could not reverse the suppression of PPARγ activity or the PTEN increase in 344SQ cells and consequently failed to prevent the EMT process. Moreover, a single injection of ApoSQ cells inhibited lung metastasis in syngeneic immunocompetent mice with enhanced PPARγ/PTEN signaling both in tumor-associated macrophages and in tumor cells. PPARγ antagonist GW9662 reversed the signaling by PPARγ/PTEN; the reduction in EMT-activating transcription factors, such as Snai1 and Zeb1; and the antimetastatic effect of the ApoSQ injection. Thus, the injection of apoptotic lung cancer cells may offer a new strategy for the prevention of lung metastasis.

Pioglitazone Reduces Hepatocellular Carcinoma Development in Two Rodent Models of Cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the deadliest malignancies worldwide due to the lack of effective treatments. Chemoprevention in high-risk patients is a promising, alternative strategy. In this study, pioglitazone was investigated for its ability to prevent hepatocarcinogenesis in two rodent models of cirrhosis.

METHODS

In the first model, male Wistar rats were given repeated, low-dose injections of diethylnitrosamine (DEN) to accurately recapitulate the progression of fibrosis to cirrhosis and HCC. In the second model, a single dose of DEN was administered to male C57Bl/6 pups at day fifteen followed by administration of a choline-deficient, L-amino acid defined, high-fat diet (CDAHFD) at week six for 24 weeks. Pioglitazone treatment started at the first signs of fibrosis in both models.

RESULTS

Pioglitazone effectively reduced fibrosis progression and HCC development in both models. Gross tumor nodules were significantly reduced after pioglitazone treatment (7.4 ± 1.6 vs. 16.6 ± 2.6 in the rat DEN model and 5.86 ± 1.82 vs. 13.2 ± 1.25 in the mouse DEN+CDAHFD model). In both models, pioglitazone reduced the activation of mitogen-activated protein kinase (MAPK) and upregulated the hepato-protective AMP-activated protein kinase (AMPK) pathway via increasing circulating adiponectin production.

CONCLUSION

Pioglitazone is an effective agent for chemoprevention in rodents and could be repurposed as a multi-targeted drug for delaying liver fibrosis and hepatocarcinogenesis.

Dietary cholesterol promotes steatohepatitis related hepatocellular carcinoma through dysregulated metabolism and calcium signaling

The underlining mechanisms of dietary cholesterol and nonalcoholic steatohepatitis (NASH) in contributing to hepatocellular carcinoma (HCC) remain undefined. Here we demonstrated that high-fat-non-cholesterol-fed mice developed simple steatosis, whilst high-fat-high-cholesterol-fed mice developed NASH. Moreover, dietary cholesterol induced larger and more numerous NASH-HCCs than non-cholesterol-induced steatosis-HCCs in diethylnitrosamine-treated mice. NASH-HCCs displayed significantly more aberrant gene expression-enriched signaling pathways and more non-synonymous somatic mutations than steatosis-HCCs (335 ± 84/sample vs 43 ± 13/sample). Integrated genetic and expressional alterations in NASH-HCCs affected distinct genes pertinent to five pathways: calcium, insulin, cell adhesion, axon guidance and metabolism. Some of the novel aberrant gene expression, mutations and core oncogenic pathways identified in cholesterol-associated NASH-HCCs in mice were confirmed in human NASH-HCCs, which included metabolism-related genes (ALDH18A1, CAD, CHKA, POLD4, PSPH and SQLE) and recurrently mutated genes (RYR1, MTOR, SDK1, CACNA1H and RYR2). These findings add insights into the link of cholesterol to NASH and NASH-HCC and provide potential therapeutic targets.

Overexpression of YTHDF1 is associated with poor prognosis in patients with hepatocellular carcinoma

In China, hepatocellular carcinoma (HCC) is the most commonly diagnosed cancer and the leading cause of cancer death in men, followed by lung and stomach cancer. There was an urgent need to identify novel prognostic biomarkers for HCC. We explored the expression pattern of m6A related proteins in HCC tissues by using TCGA in this study. We found that the m6A 'reader' YTHDF1 was significantly upregulated in HCC and was positive correlated with pathology stage. Kaplan-Meier analysis showed that Lower YTHDF1 expression level was associated with better survival of HCC patients. Furthermore, we performed GO and KEGG pathway analysis of YTHDF1 co-expressed genes and found YTHDF1 played an important role in regulating HCC cell cycle progression and metabolism. We believed that this study will provide a potential new therapeutic and prognostic target for HCC.

PLAGL1 gene function during hepatoma cells proliferation

Hepatocellular carcinoma develops as a multistep process, in which cell cycle deregulation is a central feature, resulting in unscheduled proliferation. The PLAGL1 gene encodes a homonym zinc finger protein that is involved in cell-proliferation control. We determined the genomic profile and the transcription and expression level of PLAGL1, simultaneously with that of its molecular partners p53, PPARγ and p21, in cell-lines derived from patients with liver cancer, during in vitro cell growth. Our investigations revealed that genomic and epigenetic changes of PLAGL1 are also present in hepatoma cell-lines. Transcription of PLAGL1 in tumor cells is significantly lower than in normal fibroblasts, but no significant differences in terms of protein expression were detected between these two cell-types, indicating that there is not a direct relationship between the gene transcriptional activity and protein expression. RT-PCR analyses on normal fibroblasts, used as control, also showed that PLAGL1 and p53 genes transcription occurs as an apparent orchestrated process during normal cells proliferation, which gets disturbed in cancer cells. Furthermore, abnormal trafficking of the PLAGL1 protein may occur in hepatocarcinogenesis.

Peroxisome Proliferator-Activated Receptor gamma negatively regulates liver regeneration after partial hepatectomy via the HGF/c-Met/ERK1/2 pathways

Peroxisome Proliferator-Activated Receptor gamma (PPARγ) is a nuclear receptor demonstrated to play an important role in various biological processes. The aim of this study was to determine the effect of PPARγ on liver regeneration upon partial hepatectomy (PH) in mice. Mice were subjected to two-thirds PH. Before surgery, mice were either treated with the PPARγ agonist rosiglitazone, the PPARγ antagonist GW9662 alone, or with the c-met inhibitor SGX523. Liver-to-body-weight ratio, lab values, and proliferation markers were assessed. Components of the PPARγ-specific signaling pathway were identified by western blot and qRT-PCR. Our results show that liver regeneration is being inhibited by rosiglitazone and accelerated by GW9662. Inhibition of c-Met by SGX523 treatment abrogates GW9662-induced liver regeneration and hepatocyte proliferation. Hepatocyte growth factor (HGF) protein levels were significantly downregulated after rosiglitazone treatment. Activation of HGF/c-Met pathways by phosphorylation of c-Met and ERK1/2 were inhibited in rosiglitazone-treated mice. In turn, blocking phosphorylation of c-Met significantly abrogated the augmented effect of GW9662 on liver regeneration. Our data support the concept that PPARγ abrogates liver growth and hepatocellular proliferation by inhibition of the HGF/c-Met/ERK1/2 pathways. These pathways may represent potential targets in response to liver disease and could impact on the development of molecular therapies.

MLL4 Is Required to Maintain Broad H3K4me3 Peaks and Super-Enhancers at Tumor Suppressor Genes

Super-enhancers are large clusters of enhancers that activate gene expression. Broad trimethyl histone H3 lysine 4 (H3K4me3) often defines active tumor suppressor genes. However, how these epigenomic signatures are regulated for tumor suppression is little understood. Here we show that brain-specific knockout of the H3K4 methyltransferase MLL4 (a COMPASS-like enzyme, also known as KMT2D) in mice spontaneously induces medulloblastoma. Mll4 loss upregulates oncogenic Ras and Notch pathways while downregulating neuronal gene expression programs. MLL4 enhances DNMT3A-catalyzed DNA methylation and SIRT1/BCL6-mediated H4K16 deacetylation, which antagonize expression of Ras activators and Notch pathway components, respectively. Notably, Mll4 loss downregulates tumor suppressor genes (e.g., Dnmt3a and Bcl6) by diminishing broad H3K4me3 and super-enhancers and also causes widespread impairment of these epigenomic signatures during medulloblastoma genesis. These findings suggest an anti-tumor role for super-enhancers and provide a unique tumor-suppressive mechanism in which MLL4 is necessary to maintain broad H3K4me3 and super-enhancers at tumor suppressor genes.

Spironolactone in Combination with α-glycosyl Isoquercitrin Prevents Steatosis-related Early Hepatocarcinogenesis in Rats through the Observed NADPH Oxidase Modulation

Administration of the diuretic, spironolactone (SR), can inhibit chronic liver diseases. We determined the effects of SR alone or in combination with the antioxidant α-glycosyl isoquercitrin (AGIQ) on hyperlipidemia- and steatosis-related precancerous lesions in high-fat diet (HFD)-fed rats subjected to a two-stage hepatocarcinogenesis model. Rats were fed with control basal diet or HFD, which was administered with SR alone or in combination with an antioxidant AGIQ in drinking water. An HFD increased body weight, intra-abdominal fat (adipose) tissue weight, and plasma lipids, which were reduced by coadministration of SR and AGIQ. SR and AGIQ coadministration also reduced hepatic steatosis and preneoplastic glutathione S-transferase placental form-positive foci, in association with decrease in NADPH oxidase (NOX) subunit p22phox-positive cells and an increase in active-caspase-3-positive cells in the foci. Hepatic gene expression analysis revealed that the coadministration of SR and AGIQ altered mRNA levels of lipogenic enzymes ( Scd1 and Fasn), antioxidant-related enzymes ( Catalase), NOX component ( P67phox), and anti-inflammatory transcriptional factor ( Pparg). Our results indicated that SR in combination with AGIQ had the potential of suppressing hyperlipidemia- and steatosis-related early hepatocarcinogenesis through the reduced expression of NOX subunits.

MicroRNA-1468 promotes tumor progression by activating PPAR-γ-mediated AKT signaling in human hepatocellular carcinoma

Background

Accumulating evidence confirm that aberrant microRNAs (miRNAs) expression contributes to hepatocellular carcinoma (HCC) development and progression. Previous study reported that miR-1468 showed an up-regulated tendency and might be a potential prognostic biomarker in HCC samples derived from TCGA database. However, the role of miR-1468 and its underlying mechanisms involved in the growth and metastasis of HCC remain poorly investigated.

Methods

CCK-8, EdU, colony formation and flow cytometry were used to determine proliferation, cell cycle progression and apoptosis of HCC cells in vitro. The subcutaneous tumor model in nude mice was established to detect tumor growth of HCC in vivo. The direct binding of miR-1468 to 3’UTR of Cbp/p300 interacting transactivator with Glu/Asp rich carboxy-terminal domain 2 (CITED2) and Up-frameshift protein 1 (UPF1) was confirmed by luciferase reporter assay.

Results

Here, we demonstrated that miR-1468 expression was up-regulated in HCC tissues and cell lines. Clinical analysis revealed that increased miR-1468 level was significantly correlated with malignant prognostic features and shorter survival. Gain- and loss-of-function experiments indicated that miR-1468 promoted cell proliferation, colony formation, cell cycle progression and induced apoptosis of HCC cells in vitro and in vivo. Moreover, CITED2 and UPF1 were identified as direct downstream targets of miR-1468 in HCC cells, and mediated the functional effects of miR-1468 in HCC, resulting in peroxisome proliferator-activated receptor-γ (PPAR-γ)/AKT signaling activation. In clinical samples of HCC, miR-1468 inversely correlated with the levels of CITED2 and UPF1, which were confirmed to be down-regulated in HCC. Restoration of CITED2 or UPF1 expression at least partially abolished the biological effects of miR-1468 on HCC cells. Moreover, alteration of PPAR-γ or AKT phosphorylation could reverse the function of miR-1468 in HCC.

Conclusions

Taken together, this research supports the first evidence that miR-1468 plays an oncogenic role in HCC via activating PPAR-γ/AKT pathway by targeting CITED2 and UPF1, and represents a promising therapeutic strategy for HCC patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0717-3) contains supplementary material, which is available to authorized users.

Rosiglitazone diminishes the high-glucose-induced modulation of 5-fluorouracil cytotoxicity in colorectal cancer cells

Colorectal cancer (CRC) is the third most leading cause of morbidity and mortality throughout the world. 5-fluorouracil (5-FU), which is often administrated to disrupt carcinogenesis, was found to elevate blood glucose level among CRC patients. Thus, this study was conducted to evaluate the influence of rosiglitazone on antiproliferative effect of 5-FU using cellular model. Two human colonic carcinoma cell lines (HCT 116 and HT 29) were cultured in the presence of 5-FU, rosiglitazone or in combination under normal and high glucose concentration. The drug cytotoxicity was evaluated using the MTT assay whereas the assessment of cell cycle was carried out using the flow cytometry technique. Combination index (CI) method was used to determine the drug interaction between rosiglitazone and 5-FU. High glucose diminished the cytotoxic effect of 5-FU but at a high drug dosage, this effect could be overcome. Cell cycle analysis demonstrated that 5-FU and rosiglitazone caused G1-phase arrest and S-phase arrest, respectively. CI values indicated that rosiglitazone exerted synergistic effect on 5-FU regardless of glucose levels. This study is the first to demonstrate the influence of rosiglitazone on cytotoxicity of 5-FU under normal or high glucose level. Rosiglitazone may be a promising drug for enhancing the efficacy of 5-FU in the treatment of CRC associated with hyperglycemia.

Apo-10'-lycopenoic acid inhibits cancer cell migration and angiogenesis and induces peroxisome proliferator-activated receptor γ

SCOPE

We have previously shown that apo-10'-lycopenoic acid (ALA), a derivative of lycopene through cleavage by carotene-9',10'-oxygenase, inhibits tumor progression and metastasis in both liver and lung cancer animal models. The underlying mechanism remains unknown. We hypothesized that ALA inhibits cancer cell motility and angiogenesis by up-regulating peroxisome proliferator-activated receptor γ (PPARγ) which is involved in controlling angiogenesis, tumor progression and metastasis.

METHODS AND RESULTS

ALA treatment, in dose-dependent manner, was effective at inhibiting migration and invasion of liver and lung cancer cells (HuH7 and A549) in both Transwell and wound-healing models, as well as suppressing actin remodeling and ruffling/lamellipodia formation in HuH7 and immortalized lung BEAS-2B cells. ALA treatment resulted in suppression of angiogenesis in both tube formation and aortic ring assays and inhibition of matrix metalloproteinase-2 expression and activation in both HuH7 and A549 cells. Additionally, ALA dose-dependently increased the mRNA expression and protein levels of PPARγ in human THLE-2 liver cells.

CONCLUSION

ALA inhibits cancer cell motility and angiogenesis and induces PPARγ expression, which could be one of the potential mechanisms for ALA protecting against tumor progression.

Effects of Estrogen and Estrogen Receptors on Transcriptomes of HepG2 Cells: A Preliminary Study Using RNA Sequencing

Men have a much higher incidence of hepatocellular carcinoma (HCC), the predominant form of liver cancer, than women, suggesting that estrogens play a protective role in liver cancer development and progression. To begin to understand the potential mechanisms of estrogens' inhibitory effects on HCC development, RNA sequencing was used to generate comprehensive global transcriptome profiles of the human HCC-derived HepG2 cell line following treatment of vehicle (control), estradiol (E2), estrogen receptor alpha- (ERα-) specific agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), or ERβ-specific agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) using a small set of cells. Gene ontology (GO) analysis identified increased expression of genes involved in the biological process (BP) of response to different stimuli and metabolic processes by E2 and ER agonists, which enhanced molecular function (MF) in various enzyme activities and chemical bindings. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathway analysis indicated enhanced pathways associated with carbohydrate metabolism, complement and coagulation cascades, and HIF-1 signaling pathway by E2 and ER agonists. GO analysis also identified decreased expression of genes by E2, PPT, and DPN involved in BP related to the cell cycle and cell division, which reduced MF in activity of multiple enzymes and microtubule activity. KEGG analysis indicated that E2, PPT, and DPN suppressed pathways associated with the cell cycle; E2 and PPT suppressed pathways associated with chemical carcinogenesis and drug metabolism, and DPN suppressed DNA replication, recombination, and repair. Collectively, these differentially expressed genes across HepG2 cell transcriptome involving cellular and metabolic processes by E2 and ER agonists provided mechanistic insight into protective effects of estrogens in HCC development.

Pharmacologic Inhibition of the Menin-MLL Interaction Leads to Transcriptional Repression of PEG10 and Blocks Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for approximately 85% of malignant liver tumors and results in 600,000 deaths each year, emphasizing the need for new therapies. Upregulation of menin was reported in HCC patients and high levels of menin correlate with poor patient prognosis. The protein-protein interaction between menin and histone methyltransferase mixed lineage leukemia 1 (MLL1) plays an important role in the development of HCC, implying that pharmacologic inhibition of this interaction could lead to new therapeutic strategy for the HCC patients. Here, we demonstrate that the menin-MLL inhibitor MI-503 shows antitumor activity in in vitro and in vivo models of HCC and reveals the potential mechanism of menin contribution to HCC. Treatment with MI-503 selectively kills various HCC cell lines and this effect is significantly enhanced by a combination of MI-503 with sorafenib, the standard-of-care therapy for HCC. Furthermore, MI-503 reduces sphere formation and cell migration in in vitro HCC models. When applied in vivo, MI-503 gives a strong antitumor effect both as a single agent and in combination with sorafenib in mice xenograft models of HCC. Mechanistically, treatment with MI-503 downregulates expression of several genes known to play a critical role in proliferation and migration of HCC cells, including PEG10, and displaces the menin-MLL1 complex from the PEG10 promoter, resulting in reduced H3K4 methylation and transcriptional repression. Overall, our studies reveal a mechanistic link between menin and genes involved in HCC and demonstrate that pharmacologic inhibition of the menin-MLL interaction might represent a promising therapeutic approach for HCC. Mol Cancer Ther; 17(1); 26-38. ©2017 AACR.

Communicative reprogramming non-curative hepatocellular carcinoma with low-dose metronomic chemotherapy, COX-2 inhibitor and PPAR-gamma agonist: a phase II trial

Systemic therapy for advanced hepatocellular carcinoma (HCC) is still challenging. A biomodulatory therapy approach targeting the communicative infrastructure of HCC, including metronomic low-dose chemotherapy with capecitabine, pioglitazone and rofecoxib, has been evaluated in patients with non-curative HCC. Altogether 38 patients were evaluable in this one-arm, multicenter phase II trial. The primary endpoint, median progression-free survival was 2.7 months (95% CI: 1.6-3.79) for all evaluable patients and 8.4 months (95% CI: 0-18.13) for patients ≥ 6 weeks on protocol. Median overall survival (OS) was 6.7 months (95% CI: 4.08-9.31) and 9.4 months (95% CI: 4.82-13.97), respectively. Most common adverse events were edemas grade 3, which were commonly related to the advanced stage, with 66% of the patients suffering from liver cirrhosis. Exploratory data analyses showed significant impact of ECOG performance status grade 0 versus 1 and CLIP score 0/1 versus > 1 on OS, 9.8 months (95% CI: 4.24-15.35) versus 2.7 months (95% CI: 1.03-4.36; P = 0.002), and 9.8 months (95% CI: 3.23-16.37) versus 4.4 months (95% CI: 3.14-5.66; P = 0.009), respectively. Preceding tumor surgery had significant beneficial impact on survival, as well as maximal tumor diameter of < 5 cm. The correlation of C-reactive protein decrease with significantly improved OS underlines the close link between inflammation and tumor control. Biomodulatory therapy in advanced HCC may be a low toxic, efficacious treatment and principally demonstrates that such approaches should be followed further for treatment of advanced HCC.

Regulation of the tumor suppressor PTEN by natural anticancer compounds

The tumor suppressor phosphatase and tensin homologue (PTEN) has phosphatase activity, with phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a product of phosphatidylinositol 3-kinase (PI3K), as one of the principal substrates. PTEN is a negative regulator of the Akt pathway, which plays a fundamental role in controlling cell growth, survival, and proliferation. Loss of PTEN function has been observed in many different types of cancer. Functional inactivation of PTEN as a consequence of germ-line mutations or promoter hypermethylation predisposes individuals to malignancies. PTEN undergoes posttranslational modifications, such as oxidation, acetylation, phosphorylation, SUMOylation, and ubiquitination, which influence its catalytic activity, interactions with other proteins, and subcellular localization. Cellular redox status is crucial for posttranslational modification of PTEN and its functional consequences. Oxidative stress and inflammation are major causes of loss of PTEN function. Pharmacologic or nutritional restoration of PTEN function is considered a reliable strategy in the management of PTEN-defective cancer. In this review, we highlight natural compounds, such as curcumin, indol-3 carbinol, and omega-3 fatty acids, that have the potential to restore or potentiate PTEN expression/activity, thereby suppressing cancer cell proliferation, survival, and resistance to chemotherapeutic agents.

Micro-RNA-130a-3p Regulates Gemcitabine Resistance via PPARG in Cholangiocarcinoma

BACKGROUND

The prognosis of cholangiocarcinoma (CCA) is so poor that its chemoresistance needs to be reduced. In this study, we focused on the microRNAs (miRNAs) associated with gemcitabine resistance of CCA and assessed the clinical significance of miRNAs and their target genes.

METHODS

We performed miRNA microarray analysis for two CCA cell lines (CCLP-1 and MzChA-1) and their gemcitabine-resistant (GR) cells. An miR-130a-3p mimic was induced into CCA cells using lipofection, and we used pioglitazone as a peroxisome proliferator-activated receptor-γ (PPARγ) agonist in vitro. The expression of miR-130a-3p was studied in 27 intrahepatic CCA samples after laser capture microdissection (LCM) and by immunohistochemistry from patients who had undergone curative resection from March 2004 to November 2012 at Osaka University Hospital.

RESULTS

miR-130a-3p expression was upregulated in CCLP-1-GRs and MzChA-1-GRs significantly more than in their parental cells. Transfection of the miR-130a-3p mimic into CCA cells increased gemcitabine resistance, and we detected PPARG as a target gene of miR-130a-3p. Furthermore, pioglitazone had a synergistic effect with gemcitabine and alleviated gemcitabine resistance of CCA GR cells. Moreover, clinical examination revealed that for patients who underwent adjuvant gemcitabine therapy, those who were PPARγ positive had significantly longer disease-free survival than those who were PPARγ negative (n = 5 and 11, respectively; p = 0.027).

CONCLUSIONS

Our data suggest that miR-130a-3p was associated with gemcitabine resistance in CCA through PPARG, and there is a possibility that pioglitazone can be used for the treatment of CCA.

Targeting nuclear receptors for the treatment of fatty liver disease

Ligand-activated nuclear receptors, including peroxisome proliferator-activated receptor alpha (PPARα), pregnane X receptor, and constitutive androstane receptor, were first identified as key regulators of the responses against chemical toxicants. However, numerous studies using mouse disease models and human samples have revealed critical roles for these receptors and others, such as PPARβ/δ, PPARγ, farnesoid X receptor (FXR), and liver X receptor (LXR), in maintaining nutrient/energy homeostasis in part through modulation of the gut-liver-adipose axis. Recently, disorders associated with disrupted nutrient/energy homeostasis, e.g., obesity, metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD), are increasing worldwide. Notably, in NAFLD, a progressive subtype exists, designated as non-alcoholic steatohepatitis (NASH) that is characterized by typical histological features resembling alcoholic steatohepatitis (ASH), and NASH/ASH are recognized as major causes of hepatitis virus-unrelated liver cirrhosis and hepatocellular carcinoma. Since hepatic steatosis is basically caused by an imbalance between fat/energy influx and utilization, abnormal signaling of these nuclear receptors contribute to the pathogenesis of fatty liver disease. Standard therapeutic interventions have not been fully established for fatty liver disease, but some new agents that activate or inhibit nuclear receptor signaling have shown promise as possible therapeutic targets. In this review, we summarize recent findings on the roles of nuclear receptors in fatty liver disease and discuss future perspectives to develop promising pharmacological strategies targeting nuclear receptors for NAFLD/NASH.

Hepatocyte nuclear factor 1α suppresses steatosis-associated liver cancer by inhibiting PPARγ transcription

Worldwide epidemics of metabolic diseases, including liver steatosis, are associated with an increased frequency of malignancies, showing the highest positive correlation for liver cancer. The heterogeneity of liver cancer represents a clinical challenge. In liver, the transcription factor PPARγ promotes metabolic adaptations of lipogenesis and aerobic glycolysis under the control of Akt2 activity, but the role of PPARγ in liver tumorigenesis is unknown. Here we have combined preclinical mouse models of liver cancer and genetic studies of a human liver biopsy atlas with the aim of identifying putative therapeutic targets in the context of liver steatosis and cancer. We have revealed a protumoral interaction of Akt2 signaling with hepatocyte nuclear factor 1α (HNF1α) and PPARγ, transcription factors that are master regulators of hepatocyte and adipocyte differentiation, respectively. Akt2 phosphorylates and inhibits HNF1α, thus relieving the suppression of hepatic PPARγ expression and promoting tumorigenesis. Finally, we observed that pharmacological inhibition of PPARγ is therapeutically effective in a preclinical murine model of steatosis-associated liver cancer. Taken together, our studies in humans and mice reveal that Akt2 controls hepatic tumorigenesis through crosstalk between HNF1α and PPARγ.