Cyclooxygenase-2 expression in chronic liver diseases and hepatocellular carcinoma: an immunohistochemical study

Celecoxib-mediated attenuation of non-alcoholic steatohepatitis is potentially relevant to redistributing the expression of adiponectin receptors in rats

Pharmacological inhibition of cyclooxygenase-2 (COX-2) activity ameliorated the severity of non-alcoholic steatohepatitis (NASH) rats. It is not completely understood that the role of COX-2 inhibitor celecoxib on adiponectin receptors (Adipo-R1/R2) expression in different tissues in NASH rats. Sprague-Dawley male NASH rats induced by a high-fat diet (HFD) were administrated with or without celecoxib for 8 weeks. Biochemical parameters of liver function, glucose, and lipid metabolism, and the levels of adiponectin, tumor necrosis factor-alpha (TNF-α), prostaglandin E₂ (PGE₂) in the serum or liver were collected according to the standard protocols. The mRNA and protein levels of Adipo-R1, Adipo-R2, and COX-2 in the liver, muscle, and visceral fat were performed by quantitative real-time polymerase chain reaction (q-PCR) and Western blot analysis, respectively. The results showed that celecoxib ameliorated the various clinical indicators and pathological characteristics in the NASH rats, including body weight, liver function, liver index, and redox activities in serum and hepatic samples. The serum concentrations of adiponectin and TNF-α and PGE₂ were negatively correlated. As expected, these ameliorative effects of celecoxib were associated with the gene and protein levels up-regulation of Adipo-R1, Adipo-R2 in the liver and visceral fat tissues, and seeming to be compensatory down-regulation expression in muscle tissues (P <0.05). Additionally, COX-2 protein expression was negatively correlated with serum adiponectin levels, protein expression of adiponectin receptors from the liver and visceral fat, conversely, positively correlated with those from the muscle. Our current study demonstrate that celecoxib might effectively alleviate NASH rats in a unique manner closely relevant to redistributing the expression of adiponectin receptors in the liver, visceral fat, and muscle. However, the precise molecular mechanism needs further study.

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NASH is a watershed in the progression of NAFLD.

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Finding a therapy for NASH is in urgent need.

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Pharmacological inhibition of COX-2 activity ameliorated the severity of NASH.

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Low-dose celecoxib, a COX-2 inhibitor, can improve NASH by redistributing the expression of adiponectin receptors.

A novel prostaglandin I2 agonist, ONO-1301, attenuates liver inflammation and suppresses fibrosis in non-alcoholic steatohepatitis model mice

BACKGROUND

ONO-1301 is a novel long-lasting prostaglandin (PG) I₂ mimetic with inhibitory activity on thromboxane (TX) A₂ synthase. This drug can also induce endogenous prostaglandin (PG)I2 and PGE2 levels. Furthermore, ONO-1301 acts as a cytokine inducer and can initiate tissue repair in a variety of diseases, such as pulmonary hypertension, pulmonary fibrosis, cardiac infarction, and obstructive nephropathy. In this study, our aim was to evaluate the effect of ONO-1301 on liver inflammation and fibrosis in a mouse model of non-alcoholic steatohepatitis (NASH).

METHODS

The therapeutic effects of ONO-1301 against liver damage, fibrosis, and occurrence of liver tumors were evaluated using melanocortin 4 receptor-deficient (Mc4r-KO) NASH model mice. The effects of ONO-1301 against macrophages, hepatic stellate cells, and endothelial cells were also evaluated in vitro.

RESULTS

ONO-1301 ameliorated liver damage and fibrosis progression, was effective regardless of NASH status, and suppressed the occurrence of liver tumors in Mc4r-KO NASH model mice. In the in vitro study, ONO-1301 suppressed LPS-induced inflammatory responses in cultured macrophages, suppressed hepatic stellate cell (HSC) activation, upregulated vascular endothelial growth factor (VEGF) expression in HSCs, and upregulated hepatocyte growth factor (HGF) and VEGF expression in endothelial cells.

CONCLUSIONS

The results of our study highlight the potential of ONO-1301 to reverse the progression and prevent the occurrence of liver tumors in NASH using in vivo and in vitro models. ONO-1301 is a multidirectional drug that can play a key role in various pathways and can be further analyzed for use as a new drug candidate against NASH.

The Ameliorative Effects of Saikosaponin in Thioacetamide-Induced Liver Injury and Non-Alcoholic Fatty Liver Disease in Mice

Liver disorders are a major health concern. Saikosaponin-d (SSd) is an effective active ingredient extracted from Bupleurum falcatum, a traditional Chinese medicinal plant, with anti-inflammatory and antioxidant properties. However, its hepatoprotective properties and underlying mechanisms are unknown. We investigated the effects and underlying mechanisms of SSd treatment for thioacetamide (TAA)-induced liver injury and high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in male C57BL/6 mice. The SSd group showed significantly higher food intake, body weight, and hepatic antioxidative enzymes (catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)) and lower hepatic cyclooxygenase-2 (COX-2), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and fibroblast growth factor-21 (FGF21) compared with controls, as well as reduced expression of inflammation-related genes (nuclear factor kappa B (NF-κB) and inducible nitric oxide synthase (iNOS)) messenger RNA (mRNA). In NAFLD mice, SSd reduced serum ALT, AST, triglycerides, fatty acid–binding protein 4 (FABP4) and sterol regulatory element–binding protein 1 (SREBP1) mRNA, and endoplasmic reticulum (ER)-stress-related proteins (phosphorylated eukaryotic initiation factor 2α subunit (p-eIF2α), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP). SSd has a hepatoprotective effect in liver injury by suppressing inflammatory responses and acting as an antioxidant.

Protective Effect of Nerium Oleander Distillate and Tarantula Cubensis Alcoholic Extract on Cancer Biomarkers on Colon and Liver Tissues of Rats with Experimental Colon Cancer

BACKGROUND

Colon cancers are among the three major cancer types that result in death. The research for effective treatment continues.

OBJECTIVE

The aim of this study is to determine the effects of Tarantula cubensis alcoholic extract (TCAE) and Nerium oleander (NO) distillate on the levels of midkine, TGF-β, VEGF, AFP, COX-2, IGF and caspase 3 in liver and colon tissues of experimentally induced colon cancer in rats.

METHOD

The liver and colon tissues of the rats were divided into Control, Colon Cancer (AZM), AZM+TCAE and AZM+NO groups and they were homogenized. The levels of midkine, TGF-β, VEGF, AFP, COX-2, IGF and caspase 3 in the colon and liver tissues were measured by ELISA kits.

RESULTS

All parameters levels of colon and liver tissues in the AZM group were generally higher (p<0.05) than the Control group. TCAE and NO prevented (p<0.05) the increases in midkine, TGF-β, VEGF, AFP, COX-2, IGF and caspase-3 levels in the colon. NO prevented increase of all parameters except for IGF level, while TCAE prevented (p<0.05) the increase of all values apart from COX-2 and IGF levels in the liver.

CONCLUSION

NO and TCAE may prevented at the specified marker levels of colon in the AZM induced colon cancer. The increases the level of parameters in the liver are not as severe as in the colon, due to the 18-week study period may not be sufficient for liver metastasis formationIn the future molecular studies should be done to determine the mechanisms and pathways of them more clearly.

The Ameliorative Effects of Fucoidan in Thioacetaide-Induced Liver Injury in Mice

Liver disorders have been recognized as one major health concern. Fucoidan, a sulfated polysaccharide extracted from the brown seaweed Fucus serratus, has previously been reported as an anti-inflammatory and antioxidant. However, the discovery and validation of its hepatoprotective properties and elucidation of its mechanisms of action are still unknown. The objective of the current study was to investigate the effect and possible modes of action of a treatment of fucoidan against thioacetamide (TAA)-induced liver injury in male C57BL/6 mice by serum biochemical and histological analyses. The mouse model for liver damage was developed by the administration of TAA thrice a week for six weeks. The mice with TAA-induced liver injury were orally administered fucoidan once a day for 42 days. The treated mice showed significantly higher body weights; food intakes; hepatic antioxidative enzymes (catalase, glutathione peroxidase (GPx), and superoxide dismutase (SOD)); and a lower serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and C-reactive protein (CRP) levels. Additionally, a reduced hepatic IL-6 level and a decreased expression of inflammatory-related genes, such as cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) mRNA was observed. These results demonstrated that fucoidan had a hepatoprotective effect on liver injury through the suppression of the inflammatory responses and acting as an antioxidant. In addition, here, we validated the use of fucoidan against liver disorders with supporting molecular data.

OMA1520 and OMA1774, novel 1,2,4-triazole bearing analogs of combretastatin A-4, inhibit hepatocellular carcinoma: Histological and immunohistochemical studies

Combretastatin A-4 (CA-4) received significant interest as a potential anticancer agent in recent years. Several CA-4 analogs were synthesized and investigated to enhance the activity or solve the in vivo decreased activity of CA-4.

AIM

The present study aims to investigate the chemotherapeutic and the antiproliferative effects of the mono and the dual therapy of the newly synthesized CA-4 analogs OMA1520 and OMA1774 against hepatocellularcarcinoma (HCC) induced in male adult rats by N-methylnitrosourea (MNU).

METHODS

50 male rats were divided into 5 groups of 10 animals in each group. Group I: normal healthy control; group II: MNU treated group, group III: MNU animals treated by OMA1520, group IV: MNU animals treated by OMA1774, and group V: MNU animals treated by both OMA1520 and OMA1774. The rats were assessed for liver cancer progression or inhibition by evaluating the histopathological, immunohistochemical, biochemical, and antioxidant enzyme status.

RESULTS

The present work indicated that OMA1520 and OMA1774 possessed substantial chemotherapeutic efficiency against HCC. The histological and immunohistochemical examinations of liver tissues confirmed the biochemical sera data. Also, they diminished the cytotoxic effects of MNU and restored the normal histological hepatic architecture. Both analogs restored the normal levels of liver enzymes and functions and revealed potential antioxidant effects. OMA1520 and OMA1774 reduced the inflammatory and tumor markers' elevated expressions in serum.

CONCLUSION

Substantial evidence in our results suggests that both CA-4 analogs could be possible alternative anticancer agents, and their co-administration provides a synergistic activity.

Novel combination of celecoxib and metformin improves the antitumor effect by inhibiting the growth of Hepatocellular Carcinoma

Objective: To explore the effect of COX-2 inhibitor celecoxib in combination with metformin on the prevention of Hepatocellular carcinoma (HCC) and the mechanisms involved.

Methods: HCC cell lines and an HCC rat model were treated with celecoxib, metformin or a combination of both. Cell viability and tumor formation were measured.

Results:In vitro and in vivo studies showed that treatment with a combination of celecoxib and metformin inhibited proliferation of HCC to a greater extent than either treatment alone, by reducing the phosphorylation of MTOR.

Conclusion: The study suggested that celecoxib combined with metformin would be more effective for the preventing occurrence of HCC than either treatment alone and this combination of therapy is worthy of further study.

A molecular-logic gate for COX-2 and NAT based on conformational and structural changes: visualizing the progression of liver disease

Lighting up the relevant lesion boundaries during operations is vital for guiding the effective resection of hepatopathic tissue.

Lighting up the relevant lesion boundaries during operations is vital for guiding the effective resection of hepatopathic tissue. We envisioned that molecular-logic gates, which are known for their excellent digital correlation between input and output signals, could be used to facilitate differential visualization of lesion boundaries. Herein, a series of flexible molecules, naphthalene imide-indole derivatives (IAN) were prepared and evaluated as molecular-logic gates. The input and output signals of the IAN derivatives were successfully used to highlight different hepatopathic regions in order to facilitate boundary differentiation. The IAN derivatives produce different signals due to collaborative changes in the conformation and structure. The hepatopathy-related enzymes (COX-2 and NAT) were used to induce conformational and structural changes in IAN derivatives. Based on these enzyme induced synergistic effects, IAN can sensitively emit different coloured signals such as green, cyan and blue (output signals) as a function of the different input signals, i.e. the different activity of COX-2 and NAT in solution and living cells. Significantly, the IAN derivatives were successfully used to distinguish the boundaries of hepatopathic lesions in tissues after spraying with IAN derivatives (mild cirrhosis, severe cirrhosis, in addition to early and late hepatocellular carcinoma) under a hand held lamp at 365 nm by naked eye.

Protective effect of Moringa oleifera leaves ethanolic extract against thioacetamide-induced hepatotoxicity in rats via modulation of cellular antioxidant, apoptotic and inflammatory markers

The current study was conducted to evaluate the ameliorative and protective potentials of Moringea oleifera leaves ethanolic extract (MOLE) against thioacetamide (TAA) toxicity. A total of 58 male albino rats were randomly assigned into six experimental groups. G1, rats received distilled water. G2, rats were injected with a single dose of TAA (200 mg/kg BW) i.p. G3, rats were given MOLE (300 mg/kg BW) orally for 26 days. G4, rats were injected TAA as in G2 and treated with MOLE as G3. G5, rats were kept for 26 days without treatment then on day 27 injected with TAA as in G2. G6, rats were given MOLE for 26 days then on day 27 injected with TAA. Phytochemical analysis of MOLE indicated the presence of kaempferol, kaempferol malonylglucoside, kaempferol hexoside, kaempferol -3-O-glucoside, kaempferol-3-O-acetyl-glucoside, cyanidin -3-O-hexoside, ellagic acid, quercetin, quercetin-3-O-glucoside, and apigenin glucoside. Intoxication of rats with TAA significantly elevated activities of serum AST, ALT, and ALP; concentrations of malondialdehyde, nitric oxide, and hepatic tissue protein expression of caspase 3 and COX2 with alteration of the histological structures of hepatic tissues, while it decreased serum levels of total protein, albumin, and hepatic tissue contents of reduced glutathione. Also, TAA intoxication resulted in 62.5% mortality in rats of G5. Treatment of TAA intoxicated rats (G4) with MOLE ameliorated the toxic effects of TAA on hepatic tissue structure and function. It decreased serum activities of AST, ALT, and ALP; enhanced hepatic GSH concentration; reduced pathological alterations and lipid peroxidation; and downregulated caspase 3 and COX2 proteins expression in hepatic tissue. In addition, MOLE protected rats of G6 from TAA-induced hepatic tissues injury and dysfunction, and increased survival rate of rats. In conclusion, MOLE had both ameliorating and protecting potentials against TAA-induced rats liver damage through regulation of antioxidant, anti-apoptotic, and inflammatory biomarkers. Graphical abstract.

The Carcinogenic Agent Diethylnitrosamine Induces Early Oxidative Stress, Inflammation and Proliferation in Rat Liver, Stomach and Colon: Protective Effect of Ginger Extract

Background: Diethylnitrosamine (DENA), a well-known dietary carcinogen, related to cancer initiation of various organs. The present study investigated the deleterious mechanisms involved in the early destructive changes of DENA in different organs namely, liver, stomach and colon and the potential protective effect of GE against these mechanisms. Methods: Adult male albino rats were assigned into four groups. A normal control group received the vehicle, another group was injected with a single necrogenic dose of DENA (200 mg/kg, i.p) on day 21. Two groups received oral GE (108 or 216 mg/kg) daily for 28 days. Sera, liver, stomach and colon were obtained 7 days after DENA injection. Serum aspartate transaminase and alanine transaminase were detected as well as reduced glutathione (GSH), malondialdehyde, nitric oxide metabolites, interleukin 1β, tumor necrosis factor (TNF-α), alpha-fetoprotein (AFP) and nuclear factorerythroid 2-related factor2 (Nrf2) in liver, stomach and colon. Histopathological studies and immunohistochemical examination of cyclooxygenase-2 (COX2) were conducted. Results: DENA induced elevation in liver function enzymes with significant increase in oxidation and inflammation biomarkers and AFP while decreased levels of Nrf2 in liver, stomach and colon were detected. Histologically, DENA showed degenerative changes in hepatocytes and inflammatory foci. Inflammatory foci displayed increased expression of COX2 in immunohistochemical staining. GE-pretreatment improved liver function and restored normal GSH with significant mitigation of oxidative stress and inflammatory biomarkers compared to DENA-treated group. AFP was reduced by GE in both doses, while Nrf2 increased significantly. Histology and immunostaining of hepatic COX-2 were remarkably improved in GE-treated groups in a dose dependent manner. Conclusion: GE exerted a potential anti-proliferative activity against DENA in liver, stomach and colon via Nrf2 activation, whilst suppression of oxidation and inflammation.

Suppressing growth and invasion of human hepatocellular carcinoma cells by celecoxib through inhibition of cyclooxygenase-2

Purpose: Biomarkers are lacking in hepatocellular carcinoma (HCC). Cyclooxygenase-2 (COX-2) and its metabolites play crucial roles in the process of inflammation-tumor transformation. This study was aimed to detect COX-2 expression in HCC tissues and evaluate the effects of a COX-2 inhibitor, celecoxib, on biological behaviors of HCC cell lines in vitro.

Methods: COX-2 expression was detected by immunohistochemistry on a human HCC tissue microarray. The correlations of COX-2 expression with tumor clinicopathological variables and overall survival were analyzed. The proliferation, apoptosis, cell cycle distribution, invasion capacity, and related signaling molecules of HCC cells after incubated with COX-2 inhibitor celecoxib were evaluated in vitro.

Results: Expression levels of COX-2 in HCC tissues were significantly higher than those in paracancerous tissues. The TNM stage III-IV, tumor size >5 cm, lymphovascular invasion and distant metastasis was higher in high COX-2 expression group compared with that in low COX-2 expression group. Patients with low COX-2 expression achieved better 5-year overall survival than those with high COX-2 expression. Treatment with celecoxib was sufficient to inhibit cell proliferation, promote apoptosis, and induce G0/G1 cell cycle arrest in HCC cells with concentration- and time-dependent manners. Celecoxib up-regulated E-cadherin protein through inhibiting COX-2-prostaglandin E2 (PGE2)-PGE2 receptor 2 (EP2)-p-Akt/p-ERK signaling pathway to suppress HCC cells migration and invasion.

Conclusion: High COX-2 expression was associated with advanced TNM stage, larger tumor size, increased lymphovascular invasion and short survival. Targeting inhibition of COX-2 by celecoxib exhibited anti-tumor activities by suppressing proliferation, promoting apoptosis, and inhibiting the aggressive properties of HCC cells.

Altered expression of COX-2 and TNF-α in patients with hepatocellular carcinoma

BACKGROUND AND AIM

hepatocellular carcinoma is a type of cancer related with inflammation, as 90% of cases develop in a chronic inflammation condition. Excess inflammation can affect tissue homeostasis. Cytokines and inflammatory mediators are immunological components that can influence the functioning of cells and tissues. In addition, the estrogen receptor appears to play an important role in hepatocarcinogenesis. The aim of the study was to evaluate the expression of inflammatory markers and ER in patients with hepatocellular carcinoma.

METHODS

data from 143 patients of ISCMPA were analyzed. Immunohistochemistry was performed of cyclooxygenase-2 enzyme (COX-2), nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α) and ER in paraffin-embedded hepatic tissue. The percentage of the stained area, intensity of staining and of the number of ER positive nuclei were evaluated using the ImageJ 1.50 software.

RESULTS AND CONCLUSION

there was a significant difference between the groups in terms of the percentage of marked area (p = 0.040) for COX-2 and the intensity of staining of TNF-α (p = 0.030). No significant differences were observed in any of other parameters evaluated. In conclusion, COX-2 and TNF-α are possible markers that should be further studied to determine their immunohistochemical profile and role in HCC development.

Anti-infective potential of catechins and their derivatives against viral hepatitis

Polyphenols including catechins from green tea (Camellia sinensis) have been reported to have anti-infective activities against a broad spectrum of viruses and other pathogens. During the last two decades, antiviral activities of catechins with different modes of action have been demonstrated on diverse families of viruses, such as human immunodeficiency virus, Herpes simplex virus, influenza virus, hepatitis B and C virus. In this study, we focused on the antiviral properties of catechins and their derivatives against viral hepatitis which have become a key public health issue due to their serious impact on human health with liver diseases.

Prostaglandin I2 suppresses the development of diet-induced nonalcoholic steatohepatitis in mice

Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome. Although the prostaglandin (PG)I₂ receptor IP is expressed broadly in the liver, the role of PGI₂-IP signaling in the development of NASH remains to be determined. Here, we investigated the role of the PGI₂-IP system in the development of steatohepatitis using mice lacking the PGI₂ receptor IP [IP-knockout (IP-KO) mice] and beraprost (BPS), a specific IP agonist. IP-KO and wild-type (WT) mice were fed a methionine- and choline-deficient diet (MCDD) for 2, 5, or 10 wk. BPS was administered orally to mice every day during the experimental periods. The effect of BPS on the expression of chemokine and inflammatory cytokines was examined also in cultured Kupffer cells. WT mice fed MCDD developed steatohepatitis at 10 wk. IP-KO mice developed steatohepatitis at 5 wk with augmented histologic derangements accompanied by increased hepatic monocyte chemoattractant protein-1 (MCP-1) and TNF-α concentrations. After 10 wk of MCDD, IP-KO mice had greater hepatic iron deposition with prominent oxidative stress, resulting in hepatocyte damage. In WT mice, BPS improved histologic and biochemical parameters of steatohepatitis, accompanied by reduced hepatic concentration of MCP-1 and TNF-α. Accordingly, BPS suppressed the LPS-stimulated Mcp-1 and Tnf-α mRNA expression in cultured Kupffer cells prepared from WT mice. PGI₂-IP signaling plays a crucial role in the development and progression of steatohepatitis by modulating the inflammatory response, leading to augmented oxidative stress. We suggest that the PGI₂-IP system is an attractive therapeutic target for treating patients with NASH.-Kumei, S., Yuhki, K.-I., Kojima, F., Kashiwagi, H., Imamichi, Y., Okumura, T., Narumiya, S., Ushikubi, F. Prostaglandin I₂ suppresses the development of diet-induced nonalcoholic steatohepatitis in mice.

Cyclooxygenase 2 in liver dysfunction and carcinogenesis: Facts and perspectives

The biosynthesis of prostaglandins and thromboxanes has been a focus of interest in the management of many liver diseases. Cyclooxygenases are the enzymes involved in the first step of the biosynthesis of these lipid mediators and selective inhibitors for these isoenzymes as well as pharmacological analogues of prostaglandins have been developed and are currently applied therapeutically. Here we discuss the implications of these enzymes in the onset of metabolic and lipid disorders in the liver and their potential role in the progression of the diseases towards fibrosis and hepatocellular carcinogenesis.

Expression of cyclooxygenase-2 is correlated with lncRNA-COX-2 in cirrhotic mice induced by carbon tetrachloride

Multiple long non-coding RNAs (lncRNAs) have been demonstrated to be involved in liver disease. Increased cyclooxygenase-2 (COX‑2) levels have also been reported to be involved in the progression of liver cirrhosis. In the present study, the correlations between lncRNA‑COX‑2 RNA expression levels, COX‑2 mRNA expression levels and liver fibrosis were examined. Liver fibrosis was induced by intraperitoneal injection of carbon tetrachloride (CCl4) in mice for 2 months (CCl4‑2M) or 3 months (CCl4‑3M). Liver histopathological evaluation was conducted using hematoxylin and eosin and Masson trichrome staining. Hepatic expression of COX‑2 and lncRNA‑COX‑2 was evaluated by reverse transcription‑quantitative polymerase chain reaction and immunohistochemical staining. Compared with the control group, fibrotic areas were increased four and nine times in the CCl4‑2M group and the CCl4‑3M group, respectively. LncRNA-COX-2 and COX‑2 upregulation were observed in the cirrhotic liver. COX‑2 mRNA expression levels and lncRNA-COX-2 RNA expression levels were significantly positively correlated with the fibrotic area. In addition, COX‑2 mRNA expression was significantly positively correlated with lncRNA‑COX‑2 expression. These results suggest that expression of COX‑2 and lncRNA‑COX‑2 increased with the progression of liver fibrosis. LncRNA-COX-2 may potentially be considered as a novel therapeutic target for liver fibrosis.

Cynanchum wilfordii Radix attenuates liver fat accumulation and damage by suppressing hepatic cyclooxygenase-2 and mitogen-activated protein kinase in mice fed with a high-fat and high-fructose diet

Excessive consumption of fat and fructose augments the pathological progression of nonalcoholic fatty liver disease through hepatic fibrosis, inflammation, and hepatic de novo lipogenesis. We hypothesized that supplementation with Cynanchum wilfordii extract (CWE) decreases fat accumulation in the liver by suppressing cyclooxygenase-2 (COX-2), the nuclear translocation of nuclear factor κB (NF-κB), and p38 mitogen-activated protein kinase (MAPK). The beneficial effect of CWE was evaluated in a murine model of nonalcoholic fatty liver disease. Mice were fed either a normal diet or an atherogenic diet with fructose (ATHFR) in the presence or absence of CWE (50, 100, or 200 mg/kg; n=6/group). Treatment with ATHFR induced a hepatosplenomegaly-like condition (increased liver and spleen weight); this pathological change was attenuated in the presence of CWE. The ATHFR group exhibited impaired liver function, as evidenced by increased blood levels of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, fat accumulation in the liver, and lipid profiles. Supplementation of CWE (100 and 200 mg/kg, P<.05) ameliorated these impaired liver functions. Atherogenic diet with fructose increased the protein levels of COX-2 and p38 MAPK, as well as the nuclear translocation of NF-κB. These signaling pathways, which are associated with the inflammatory response, were markedly suppressed after CWE treatment (100 and 200 mg/kg). In summary, CWE supplementation reduced high-fat and high-fructose diet-induced fat accumulation and damage in the liver by suppressing COX-2, NF-κB, and p38 MAPK.

Characterization of Cyclooxygenase-2 and its induction pathways in response to high lipid diet-induced inflammation in Larmichthys crocea

The present study was conducted to investigate the effects of a high-lipid diet (HLD) on cyclooxygenase (Cox)-2 expression and the signalling pathways related to low-grade inflammation in the large yellow croaker (Larmichthys crocea). An isolated 2508 bp cDNA clone of cox-2 contained an open reading frame spanning 1827 bp encoding a protein with 608 amino acid residues. The over-expression of cox-2 was consistent with the activation of c-Jun N-terminal kinases (JNKs) and p38 mitogen-activated protein kinase (MAPK) in HLD-fed fish. The activation of the activator protein-1 (AP-1) and the nuclear transcription factor kappa-B (NF-κB) signalling pathways in HLD-fed fish and the significant increase of cox-2 promoter-luciferase activity in vitro indicated that AP-1 and NF-κB could combine cox-2 promoter to promote its transcription, respectively. Together, HLD-induced inflammation up-regulates cox-2 expression via JNKs and p38 MAPK-dependent NF-κB and AP-1 pathways. The present study provides important insight into the signal transduction pathways involved in HLD-induced inflammation, which is detrimental to the health and production of fish as well as to the health of fish consumers.

Intrahepatic transplantation of adipose-derived stem cells attenuates the progression of non-alcoholic fatty liver disease in rats

Non‑alcoholic fatty liver disease (NAFLD) is one of the major causes of chronic liver injury affecting the general health of various populations. In the present study, adipose tissue‑derived stem cells (ADSCs), which were isolated from the adipose tissues of Sprague‑Dawley rats, were transplanted into the liver of high‑fat‑diet‑induced NAFLD rats via the portal vein to attenuate the disease progression of NAFLD. The results demonstrated that ADSC transplantation reduced the serum levels of alanine aminotransferase, total bilirubin, total cholesterol, triglycerides and fatty acids, and reduced the content of malondialdehyde in the liver homogenates. By contrast, ADSC transplantation caused a significant increase in superoxide dismutase activity. These data suggested that the ADSC transplantation improved the liver function, and reduced lipid metabolism and oxidative stress. In addition, the hepatic pathological changes were decelerated, lipid accumulation was reduced, and serum levels of the pro‑inflammatory factors, tumor necrosis factor‑α and interleukin‑6, were downregulated by the ADSC transplantation. Taken together, transplantation with ADSCs attenuates the disease progression of high‑fat‑diet induced NAFLD, therefore, may offer a potential therapeutic approach for the treatment of NAFLD.

Green Tea Lowers Hepatic COX-2 and Prostaglandin E2 in Rats with Dietary Fat-Induced Nonalcoholic Steatohepatitis

Green tea extract (GTE) protects against nonalcoholic steatohepatitis (NASH) by decreasing hepatic steatosis and nuclear factor kappa B (NFκB) activation. We hypothesized that hypolipidemic and anti-inflammatory activities of GTE would protect against NASH by reducing cyclooxygenase-2 (COX-2), an NFκB-dependent enzyme, and prostaglandin E2 (PGE2) in a dietary fat-induced obese model. Male Wistar rats were fed a low-fat diet containing no GTE or a high-fat (HF) diet containing GTE at 0%, 1%, or 2% for 8 weeks. Insulin resistance and total hepatic fatty acids increased following HF feeding (P<.05) and these were normalized by GTE at 1-2%. GTE (1-2%) normalized hepatic malondialdehyde without affecting cytochrome P450 2E1 mRNA expression, which was otherwise increased by HF feeding. HF-mediated increases in hepatic COX-2 protein and activity as well as PGE2 concentrations were normalized by GTE (1-2%). COX-2 activity and PGE2 were correlated to each other, and to serum alanine aminotransferase (ALT) and hepatic NFκB-binding activity (P<.05; r=0.28-0.49). GTE attenuated HF-mediated increases in total hepatic n-6 and n-3, without affecting the n-6/n-3 ratio. GTE did not affect HF-mediated increases in n-6 in nonesterified fatty acid (NEFA) and phospholipid pools, whereas n-3 and n-6/n-3 in both pools were unaffected by GTE and HF feeding. GTE decreased total hepatic arachidonic acid without affecting HF-mediated increases in arachidonic acid in NEFA or phospholipid pools. Thus, GTE attenuates lipid peroxidation and PGE2 accumulation by decreasing COX-2 activity independent of arachidonic acid availability and supports an additional mechanism by which GTE protects against liver injury during NASH in an HF-feeding model.

Comparative analysis and modeling of the severity of steatohepatitis in DDC-treated mouse strains

Background

Non-alcoholic fatty liver disease (NAFLD) has a broad spectrum of disease states ranging from mild steatosis characterized by an abnormal retention of lipids within liver cells to steatohepatitis (NASH) showing fat accumulation, inflammation, ballooning and degradation of hepatocytes, and fibrosis. Ultimately, steatohepatitis can result in liver cirrhosis and hepatocellular carcinoma.

Methodology and Results

In this study we have analyzed three different mouse strains, A/J, C57BL/6J, and PWD/PhJ, that show different degrees of steatohepatitis when administered a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) containing diet. RNA-Seq gene expression analysis, protein analysis and metabolic profiling were applied to identify differentially expressed genes/proteins and perturbed metabolite levels of mouse liver samples upon DDC-treatment. Pathway analysis revealed alteration of arachidonic acid (AA) and S-adenosylmethionine (SAMe) metabolism upon other pathways. To understand metabolic changes of arachidonic acid metabolism in the light of disease expression profiles a kinetic model of this pathway was developed and optimized according to metabolite levels. Subsequently, the model was used to study in silico effects of potential drug targets for steatohepatitis.

Conclusions

We identified AA/eicosanoid metabolism as highly perturbed in DDC-induced mice using a combination of an experimental and in silico approach. Our analysis of the AA/eicosanoid metabolic pathway suggests that 5-hydroxyeicosatetraenoic acid (5-HETE), 15-hydroxyeicosatetraenoic acid (15-HETE) and prostaglandin D2 (PGD2) are perturbed in DDC mice. We further demonstrate that a dynamic model can be used for qualitative prediction of metabolic changes based on transcriptomics data in a disease-related context. Furthermore, SAMe metabolism was identified as being perturbed due to DDC treatment. Several genes as well as some metabolites of this module show differences between A/J and C57BL/6J on the one hand and PWD/PhJ on the other.

The role of inflammation and liver cancer

Persistent inflammation is known to promote and exacerbate malignancy. Primary liver cancer, mostly hepatocellular carcinoma (HCC), is a clear example of inflammation-related cancer as more than 90 % of HCCs arise in the context of hepatic injury and inflammation. HCC represents the fifth most common malignancy and the third leading cause of cancer-related death worldwide with about one million new cases diagnosed every year with almost an equal number of deaths. Chronic unresolved inflammation is associated with persistent hepatic injury and concurrent regeneration, leading to sequential development of fibrosis, cirrhosis, and eventually HCC. Irrespective of the intrinsic differences among various etiological factors, a common denominator at the origin of HCC is the perpetuation of a wound-healing response activated by parenchymal cell death and the resulting inflammatory cascade. Hence, the identification of fundamental inflammatory signaling pathways causing transition from chronic liver injury to dysplasia and HCC could depict new predictive biomarkers and targets to identify and treat patients with chronic liver inflammation. This chapter critically discusses the roles of several major cytokines, chemokines, growth factors, transcription factors, and enzymes as well as a distinct network of inflammatory signaling pathways in the development and progression of HCC. It also highlights and analyzes preclinical animal studies showing innovative approaches of targeting inflammatory mediators and signaling by a variety of natural compounds and synthetic agents to achieve effective therapy as well as prevention of hepatic malignancy. Additionally, current limitations and potential challenges associated with the inhibition of inflammatory signaling as well as future directions of research to accelerate clinical development of anti-inflammatory agents to prevent and treat liver cancer are presented.

Disruption of tumor suppressor gene Hint1 leads to remodeling of the lipid metabolic phenotype of mouse liver

A lipidomic and metabolomic investigation of serum and liver from mice was performed to gain insight into the tumor suppressor gene Hint1. A major reprogramming of lipid homeostasis was found in both serum and liver of Hint1-null (Hint(-/-)) mice, with significant changes in the levels of many lipid molecules, as compared with gender-, age-, and strain-matched WT mice. In the Hint1(-/-) mice, serum total and esterified cholesterol were reduced 2.5-fold, and lysophosphatidylcholines (LPCs) and lysophosphatidic acids were 10-fold elevated in serum, with a corresponding fall in phosphatidylcholines (PCs). In the liver, MUFAs and PUFAs, including arachidonic acid (AA) and its metabolic precursors, were also raised, as was mRNA encoding enzymes involved in AA de novo synthesis. There was also a significant 50% increase in hepatic macrophages in the Hint1(-/-) mice. Several hepatic ceramides and acylcarnitines were decreased in the livers of Hint1(-/-) mice. The changes in serum LPCs and PCs were neither related to hepatic phospholipase A2 activity nor to mRNAs encoding lysophosphatidylcholine acetyltransferases 1-4. The lipidomic phenotype of the Hint1(-/-) mouse revealed decreased inflammatory eicosanoids with elevated proliferative mediators that, combined with decreased ceramide apoptosis signaling molecules, may contribute to the tumor suppressor activity of Hint1.

Constitutive activation of AMPK α1 in vascular endothelium promotes high-fat diet-induced fatty liver injury: role of COX-2 induction

BACKGROUND AND PURPOSE

AMP-activated protein kinase (AMPK), an important regulator of energy metabolism, comprises three (α, β and γ) subunits, each with a unique tissue distribution. As AMPK has a wide range of protein and gene targets, defining its role has been difficult. Here, we have studied a transgenic mouse model overexpressing the constitutively active α1 subunit of AMPK in endothelial cells (EC-AMPK) to elucidate its role in energy homeostasis.

EXPERIMENTAL APPROACH

Wild-type and EC-AMPK mice were fed with a high fat diet for 16 weeks. Drugs (or vehicles) were given daily by oral gavage. Body weight, fat mass composition, glucose and lipid levels were monitored regularly. Tissues including aortae and liver were collected for quantitative RT-PCR, Western blotting, elisa, histological and biochemical evaluations.

KEY RESULTS

Compared with wild-type animals, high fat diet caused more severe metabolic defects in EC-AMPK mice, which exhibited increased body weight and fat mass, elevated blood pressure, augmented glucose and lipid levels, impaired glucose tolerance, hepatomegaly and steatohepatitis. Constitutive activation of AMPK α1 in endothelial cells induced COX-2 expression and arterial inflammation. Genes involved in lipid metabolism were down-regulated in aortae and livers of EC-AMPK mice. Chronic treatment with selective COX-2 inhibitors, celecoxib or nimesulide, significantly ameliorated arterial inflammation, steatohepatitis and hyperlipidaemia in EC-AMPK mice, without altering their blood pressure or clotting.

CONCLUSIONS AND IMPLICATIONS

Constitutive activation of endothelial AMPK α1 promotes vascular inflammation and the development of obesity-induced fatty livers largely via induction of COX-2.

Celecoxib ameliorates portal hypertension of the cirrhotic rats through the dual inhibitory effects on the intrahepatic fibrosis and angiogenesis

BACKGROUND

Increased intra-hepatic resistance to portal blood flow is the primary factor leading to portal hypertension in cirrhosis. Up-regulated expression of cyclooxygenase-2 (COX-2) in the cirrhotic liver might be a potential target to ameliorate portal hypertension.

OBJECTIVE

To verify the effect of celecoxib, a selective inhibitor of COX-2, on portal hypertension and the mechanisms behind it.

METHODS

Cirrhotic liver model of rat was established by peritoneal injection of thiacetamide (TAA). 36 rats were randomly assigned to control, TAA and TAA+celecoxib groups. Portal pressures were measured by introduction of catheters into portal vein. Hepatic fibrosis was assessed by the visible hepatic fibrotic areas and mRNAs for collagen III and α-SMA. The neovasculature was determined by hepatic vascular areas, vascular casts and CD31 expression. Expressions of COX-2, vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2) and related signal molecules were quantitated.

RESULTS

Compared with TAA group, the portal pressure in TAA+celecoxib group was significantly decreased by 17.8%, p<0.01. Celecoxib treatment greatly reduced the tortuous hepatic portal venules. The data of fibrotic areas, CD31expression, mRNA levels of α-SMA and collagen III in TAA+celecoxib group were much lower than those in TAA group, p<0.01. Furthermore, the up-regulation of hepatic mRNA and protein levels of VEGF, VEGFR-2 and COX-2 induced by TAA was significantly inhibited after celecoxib treatment. The expressions of prostaglandin E2 (PGE2), phosphorylated extracellular signal-regulated kinase (p-ERK), hypoxia-inducible factor-1α (HIF-1α), and c-fos were also down-regulated after celecoxib treatment.

CONCLUSIONS

Long term administration of celecoxib can efficiently ameliorate portal hypertension in TAA rat model by its dual inhibitory effects on the intrahepatic fibrosis and angiogenesis. The anti-angiogenesis effect afforded by celecoxib may attribute to its modulation on VEGF/VEGFR-2 through the down-regulation of integrated signal pathways involving PGE2- HIF-1α- VEGF and p-ERK- c-fos- VEGFR-2.

Elevated expression of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 in primary sclerosing cholangitis: ιmplications for cholangiocarcinogenesis

Cholangiocarcinoma (CCA) occurs frequently in primary sclerosing cholangitis (PSC). Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) induced by inflammation are believed to mediate prostaglandin E2 (PGE2) production thereby promoting carcinogenesis. Their expression in PSC-associated CCA tissues and non-neoplastic bile duct epithelial cells (BDECs) in PSC was investigated. COX-2 and mPGES-1 levels in 15 PSC patients (7 with CCA) were scored using immunohistochemical staining. The results were compared with those obtained in CCA tissues and non-neoplastic BDECs (controls) of 15 sporadic CCA patients. Non-neoplastic BDECs from large and small bile ducts were investigated separately. The mRNA expression levels of COX-2 and mPGES-1 in CCA tissues were analyzed by quantitative polymerase chain reaction. Ki-67 immunostaining was performed to evaluate cell proliferation. COX-2 was strongly expressed in PSC-associated CCA tissues and non-neoplastic BDECs in PSC. This expression was significantly upregulated in both compared with sporadic CCA tissues and non-neoplastic BDECs in sporadic CCA (both P<0.01). mPGES-1 was expressed at moderate to strong levels in PSC. Compared with controls, the expression was significantly higher in non-neoplastic small BDECs (P<0.01). COX-2 mRNA levels were significantly higher in PSC-associated tissues than in sporadic CCA tissues (P<0.01). Conversely, no differences were observed in mPGES-1 mRNA levels. Ki-67 labeling indices were higher in PSC-associated CCA tissues and non-neoplastic BDECs in PSC than in controls. In conclusion, COX-2 and mPGES-1 were highly expressed in PSC-associated CCA tissues and non-neoplastic BDECs in PSC, suggesting the involvement of COX-2 and mPGES-1 in cholangiocarcinogenesis.

Novel combination of sorafenib and celecoxib provides synergistic anti-proliferative and pro-apoptotic effects in human liver cancer cells

Molecular targeted therapy has shown promise as a treatment for advanced hepatocellular carcinoma (HCC). Sorafenib, a multikinase inhibitor, recently received FDA approval for the treatment of advanced HCC. However, although sorafenib is well tolerated, concern for its safety has been expressed. Celecoxib (Celebrex®) is a selective cyclooxygenase-2 (COX-2) inhibitor which exhibits antitumor effects in human HCC cells. The present study examined the interaction between celecoxib and sorafenib in two human liver tumor cell lines HepG2 and Huh7. Our data showed that each inhibitor alone reduced cell growth and the combination of celecoxib with sorafenib synergistically inhibited cell growth and increased apoptosis. To better understand the molecular mechanisms underlying the synergistic antitumor activity of the combination, we investigated the expression profile of the combination-treated liver cancer cell lines using microarray analysis. Combination treatment significantly altered expression levels of 1,986 and 2,483 transcripts in HepG2 and Huh7 cells, respectively. Genes functionally involved in cell death, signal transduction and regulation of transcription were predominantly up-regulated, while genes implicated in metabolism, cell-cycle control and DNA replication and repair were mainly down-regulated upon treatment. However, combination-treated HCC cell lines displayed specificity in the expression and activity of crucial factors involved in hepatocarcinogenesis. The altered expression of some of these genes was confirmed by semi-quantitative and quantitative RT-PCR and by Western blotting. Many novel genes emerged from our transcriptomic analyses, and further functional analyses may determine whether these genes can serve as potential molecular targets for more effective anti-HCC strategies.

Evaluation of epigenetic modulation of cyclooxygenase-2 as a prognostic marker for hepatocellular carcinoma

Cyclooxygenases (COX-1 and 2) catalyze the first step in prostanoid biosynthesis. They are implicated in homeostatic processes with an important role in inflammation and carcinogenesis. In the liver, COX-2 expression is restricted to proliferation or dedifferentiation situations. The COX-2 promoter contains numerous CpG islands that, when hypermethylated, result in transcriptionally silencing thus regulating the growth of carcinoma cells. In this work, we investigated whether a correlation exists between COX-2 expression and methylation signatures at the 5'region of the gene in hepatoma cell lines and human hepatocellular carcinoma (HCC). We also examined the acetylation status of the COX-2 promoter and the effects of histone deacetylase (HDAC) inhibitors on COX-2 expression. Our results suggest a significant association between reduced COX-2 expression and promoter hypermethylation of COX-2 and histone deacetylation in some hepatoma cell lines and in HCC. Treatment with demethylating agents or HDAC inhibitors restored the expression of COX-2. Moreover, in an HCC cohort, a statistically significant inverse association was observed between COX-2 mRNA levels and promoter methylation. In agreement with these data, a reduction of overall survival of the patients was observed after decreased COX-2 expression by promoter hypermethylation and histone H3 hypoacetylation.

Increased hepatic expression of TLR2 and TLR4 in the hepatic inflammation-fibrosis-carcinoma sequence

We evaluated expression of TLR2, TLR4 and proinflammatory genes [NF-κB, TNF-α, cyclooxygenase-2 (COX-2)] in liver samples of patients in different stages of liver disease. Fifteen patients with unexplained transaminases elevation (reference group), 22 with viral chronic hepatitis (hepatitis group), 14 with virus-induced severe fibrosis/cirrhosis (cirrhosis group) and 10 with hepatocarcinoma (hepatocarcinoma group) were consecutively included in the study. Quantification of TLR2, TLR4, NF-κB, TNF-α and COX-2 mRNA was done by real-time RT-PCR and TLR2 and TLR4 protein expression was evaluated by immunohistochemistry. Compared with reference, TLR2 and TLR4 mRNA was increased in hepatitis (TLR2: 2.66 ± 0.69; TLR4: 3.11 ± 0.79; P < 0.05) and cirrhosis (TLR2: 2.14 ± 0.5; TLR4: 1.74 ± 0.27; P < 0.05) and decreased in hepatocarcinoma (TLR2: 0.48 ± 0.15; TLR4: 0.54 ± 0.10; P < 0.05). This associated with increased TNF-α and COX-2 mRNA in hepatitis (TNF-α: 3.24 ± 0.79; COX-2: 2.47 ± 0.36; P < 0.05) and cirrhosis (TNF-α: 1.73 ± 0.28; COX-2: 1.8 ± 0.35, P < 0.05), whereas NF-κB mRNA was increased in hepatitis (2.42 ± 0.31; P < 0.05) and unchanged in cirrhosis (1.34 ± 0.17; P = 0.3). Hepatocarcinoma presented increased COX-2 mRNA (1.63 ± 0.15; P < 0.05) and maintained (at decreased levels) mRNA of NF-κB (0.52 ± 0.12) and TNF-α (0.52 ± 0.12; P < 0.05, all genes). Immunohistochemistry confirmed increased expression of TLR2 and TLR4 in hepatitis and cirrhosis and maintained expression in hepatocarcinoma. Upregulation of TLR2, TLR4 and their proinflammatory mediators is associated with virus-induced hepatic IFC sequence.

Celecoxib, a selective cyclooxygenase-2 inhibitor, lowers plasma cholesterol and attenuates hepatic lipid peroxidation during carbon-tetrachloride-associated hepatotoxicity in rats

Cyclooxygenase-2 (COX-2) expression and prostaglandin production are suggested to play important, complex roles in the pathogenesis of various liver diseases. Studies on the effects of COX-2 inhibitors on the progression of liver fibrosis present controversial results, and the proposed therapeutic potential of these agents in chronic liver disease is predicated largely on their effectiveness in modulating hepatic stellate cell activation in vitro. This study investigated the modulatory effect of celecoxib, a selective COX-2 inhibitor, in CCl(4)-mediated hepatotoxicity in rats. Thirty Wistar albino rats, weighing 120-180 g, were assigned into five groups of 6 rats/group. Groups 1 and 2 received saline (10 mL/kg) and CCl(4) (80 mg/kg), respectively. Group 3 was given celecoxib (5.7 mg/kg), whereas groups 4 and 5 were pretreated with 2.9 and 5.7 mg/kg/day of celecoxib, respectively, 1 hour before CCl(4) treatment. Plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities increased significantly by 118.5, 150.0, and 51.3%, respectively, with an accompanying decrease (P < 0.05) in total protein and albumin after CCl(4) treatment. Hepatotoxicity was associated with a significant increase in plasma cholesterol, hepatic lipid peroxidation (LPO), and severe hepatic necrosis with marked fatty and cellular (i.e., mononuclear cells) infiltration. Although celecoxib neither reduced CCl(4)-induced increases in marker enzymes of hepatotoxicity nor significantly attenuated hepatic necrosis, it, however, was effective in reducing elevated cholesterol by 16.5 and 20.8% and LPO by 12.9 and 35.5% at 2.9 and 5.7 mg/kg, respectively. Data suggest that COX-2 inhibitors may be effective in controlling hypercholesterolemia and peroxidative changes associated with liver injury.

Immunodetection of cyclooxygenase-2 (COX-2) is restricted to tissue macrophages in normal rat liver and to recruited mononuclear phagocytes in liver injury and cholangiocarcinoma

It has been suggested that cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis is associated with liver inflammation and carcinogenesis. The aim of this study is to identify the cellular source of COX-2 expression in different stages, from acute liver injury through liver fibrosis to cholangiocarcinoma (CC). We induced in rats acute and "chronic" liver injury (thioacetamide (TAA) or carbon tetrachloride (CCl(4))) and CC development (TAA) and assessed COX-2 gene expression in normal and damaged liver tissue by RT-PCR of total RNA. The cellular localization of COX-2 protein in liver tissue was analyzed by immunohistochemistry as well as in isolated rat liver cells by Western blotting. The findings were compared with those obtained in human cirrhotic liver tissue. The specificity of the antibodies was tested by 2-DE Western blot and mass spectrometric identification of the positive protein spots. RT-PCR analysis of total RNA revealed an increase of hepatic COX-2 gene expression in acutely as well as "chronically" damaged liver. COX-2-protein was detected in those ED1(+)/ED2(+) cells located in the non-damaged tissue (resident tissue macrophages). In addition COX-2 positivity in inflammatory mononuclear phagocytes (ED1(+)/ED2(-)), which were also present within the tumoral tissue was detected. COX-2 protein was clearly detectable in isolated Kupffer cells as well as (at lower level) in isolated "inflammatory" macrophages. Similar results were obtained in human cirrhotic liver. COX-2 protein is constitutively detectable in liver tissue macrophages. Inflammatory mononuclear phagocytes contribute to the increase of COX-2 gene expression in acute and chronic liver damage induced by different toxins and in the CC microenvironment.

Reciprocal regulation of NADPH oxidases and the cyclooxygenase-2 pathway

The objective of this work was to analyze the possible association between cyclooxygenase-2 (COX-2) and NADPH oxidases (NOX) in liver cells, in response to various proinflammatory and toxic insults. First, we observed that treatment of Chang liver (CHL) cells with various COX-2 inducers increased reactive oxygen species (ROS) production concomitant with GSH depletion, phorbol 12-myristate 13-acetate (PMA) being the most effective treatment. Moreover, early changes in the oxidative status induced by PMA were inhibited by glutathione ethyl ester, which also impeded COX-2 induction. In fact, CHL cells expressed NOX1 and NOX4, although only NOX4 expression was up-regulated in the presence of PMA. Knock-down experiments suggested that PMA initiated a pathway in which NOX1 activation controlled COX-2 expression and activity, which, in turn, induced NOX4 expression by activation of the prostaglandin receptor EP4. In addition, CHL cells overexpressing COX-2 showed higher NOX4 expression and ROS content, which were decreased in the presence of the COX-2 inhibitor DFU. Interestingly, we found that addition of prostaglandin E(2) (PGE(2)) also induced NOX4 expression and ROS production, which might promote cell adhesion. Finally, we determined that NOX4 induction by PGE(2) was dependent on ERK1/2 signaling. Taken together, these results indicate that NOX proteins and COX-2 are reciprocally regulated in liver cells.

Cyclooxygenase-2 -765 G/C polymorphisms and susceptibility to hepatitis B-related liver cancer in Han Chinese population

To investigate the relationship of cyclooxygenase-2 (COX-2) polymorphisms [COX-2 -765 G/C (rs 20417)] and susceptibility to hepatitis B-related liver cancer in Han Chinese population. The polymorphisms of COX-2 -765 G/C was detected by polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) in 300 patients with hepatitis B, 300 patients with cirrhosis, 300 patients with primary liver carcinoma and 300 health controls. The COX-2 -765 G/C genotypes were GG, GC and CC. There frequencies in the hepatitis B patients were 80.33, 17.67 and 2.00%; in the cirrhosis patients were 77.67, 18.00 and 4.33%; in the patients with primary liver carcinoma were 65.67, 28.33 and 6.00% and in the heathy controls were 87.00, 12.33 and 0.67%, respectively, COX-2 -765 C allele carriers had an increased risk of hepatitis B-related liver cancer. COX-2 -765 C allele carriers having drinking history or family history of liver cancer had higher risk for HCC. COX-2 -765 C allele genotype, drinking history and family history of liver cancer may increase the susceptibility to hepatitis B-related liver cancer in Gansu province, China.

San-Huang-Xie-Xin-Tang extract suppresses hepatitis C virus replication and virus-induced cyclooxygenase-2 expression

Chronic hepatitis C virus (HCV) infection is associated with chronic inflammation of liver, which leads to the development of cirrhosis and hepatocellular carcinoma (HCC). Because of severe side effects and only a 50-70% cure rate in genotype 1 HCV-infected patients upon current standard treatment with pegylated interferon-α plus ribavirin, new therapeutic regimens are still needed. San-Huang-Xie-Xin-Tang (SHXT) is a transitional Chinese herbal formula, composed of Rhei rhizoma, Scutellaria radix and Coptidis rhizome, and possesses anti-inflammatory effect. Here, we describe a (+)-catechin-containing fraction extracted from SHXT, referred as SHXT-frC, exhibited effective inhibition of HCV replication, with selectivity index value (SI; CC50 /EC50) of 84, and displayed synergistic anti-HCV effects when combined with interferon-α, HCV protease inhibitor telaprevir or polymerase inhibitor 2'-C-methylcytidine. The activation of factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) signalling pathway has particular relevance to HCV-associated HCC. SHXT-frC treatment also caused a concentration-dependent decrease in the induction of COX-2 and NF-κB expression caused by either HCV replication or HCV NS5A protein. Collectively, SHXT-frC could be an adjuvant treatment for patients with HCV-induced liver diseases.

Inhibitory effect of phytoglycoprotein (24 kDa) on hepatocarcinogenesis in N-nitrosodiethylamine-treated ICR mice

Objectives

Hepatocellular carcinoma (HCC) is becoming one of the most prominent types of cancer in the world. For a long time in Korea Zanthoxylum piperitum DC (ZPDC) has been used in folk medicine to cure several cancers and inflammation. This study was designed to investigate whether ZPDC glycoprotein protected liver tissues against hepatocarcinogenic compounds such as N-nitrosodiethylamine (DEN).

Methods

To study the chemopreventive effect of ZPDC glycoprotein on hepatocarcinogenesis, ICR mice were injected intraperitoneally with DEN (50 mg/kg) for four weeks. We evaluated the indicators of liver tissue damage (the activity of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS)), antioxidative enzymes (activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx)), hepatocarcinogenic indicator (heat shock protein (HSP) 70) and hepatocarcinogenic signals (activity of nuclear factor (NF)-κB, cyclooxygenase (COX)-2, and matrix metalloproteinase (MMP)-9) using biochemical methods and immunoblot analysis.

Key findings

The results obtained from this study revealed that ZPDC glycoprotein (20 mg/kg) decreased the levels of LDH, ALT, and TBARS, whereas the activity of SOD and GPx increased in the DEN-treated ICR mice. With respect to the hepatocarcinogenic indicator and hepatocarcinogenic signals, HSP70, NF-κB, COX-2, and MMP-9 activity decreased.

Conclusion

The findings suggested that ZPDC glycoprotein prevented damage to liver tissue caused by DEN in the experimental mouse model.

Enhanced expression of pro-inflammatory mediators and liver X-receptor-regulated lipogenic genes in non-alcoholic fatty liver disease and hepatitis C

NAFLD (non-alcoholic fatty liver disease) is one of the most frequent chronic liver diseases worldwide. The metabolic factors associated with NAFLD are also determinants of liver disease progression in chronic HCV (hepatitis C virus) infection. It has been reported that, besides inducing hepatic fatty acid biosynthesis, LXR (liver X receptor) regulates a set of inflammatory genes. We aimed to evaluate the hepatic expression of LXRα and its lipogenic and inflammatory targets in 43 patients with NAFLD, 44 with chronic HCV infection and in 22 with histologically normal liver. Real-time PCR and Western blot analysis were used to determine hepatic expression levels of LXRα and related lipogenic and inflammatory mediators in the study population. We found that the LXRα gene and its lipogenic targets PPAR-γ (peroxisome-proliferator-activated receptor-γ), SREBP (sterol-regulatory-element-binding protein)-1c, SREBP-2 and FAS (fatty acid synthase) were overexpressed in the liver of NAFLD and HCV patients who had steatosis. Moreover, up-regulation of inflammatory genes, such as TNF (tumour necrosis factor)-α, IL (interleukin)-6, OPN (osteopontin), iNOS (inducible NO synthase), COX (cyclo-oxygenase)-2 and SOCS (suppressors of cytokine signalling)-3, was observed in NAFLD and HCV patients. Interestingly, TNF-α, IL-6 and osteopontin gene expression was lower in patients with steatohepatitis than in those with steatosis. In conclusion, hepatic expression of LXRα and its related lipogenic and inflammatory genes is abnormally increased in NAFLD and HCV patients with steatosis, suggesting a potential role of LXRα in the pathogenesis of hepatic steatosis in these chronic liver diseases.

The effects of the stromal cell-derived cyclooxygenase-2 metabolite prostaglandin E2 on the proliferation of colon cancer cells

It is well known that tumor-surrounding stromal tissues support tumor development through secreting soluble factors such as various cytokines, chemokines, and growth factors. It has also been suggested that tumor-associated fibroblast and immune cells have a high expression of cyclooxygenase-2 (COX-2) and produce and secrete several prostaglandins (PGs) to adjacent cancer tissues. From these findings, we assumed that COX-2 inhibition might have an anticancer effect on cancer cells even without COX-2 expression in COX-2-dependent mechanisms through blocking the effect of stroma-derived PGs. Here, because of the complex involvement of various factors in vivo, we investigated this possibility with an in vivo-mimicking model using a Transwell system. To test our hypothesis, we used COX-2-transfected cell lines as stromal cells in our model. When we cocultured cancer cells (LS174T cells without COX-2 expression) with COX-2-high stromal cells in the Transwell membrane system, we observed that the proliferation of cancer cells was promoted and vascular endothelial growth factor synthesis was up-regulated significantly. These effects were blocked completely by COX-2 inhibitors and phosphoinositide-3-kinase inhibitors and partially by the PG E(2) receptor 4 antagonist. Even if some cancer cells did not express COX-2, they were found to have expression of PG receptors and PG-related downstream signaling molecules associated with cell viability. Our observation suggests that these cells can be influenced by PGs derived from stromal tissues. These findings also suggest that COX-2 inhibitors can be used to control the interaction between cancer and surrounding stromal tissues and suppress the proliferation of cancer cells regardless of the expression of COX-2 in cancer cells.

[Hepatitis C virus infection and hepatocarcinogenesis]

It is evidenced that both HBV and HCV infections may cause chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC). HCV is considered as an oncogen virus. The mechanism of carcinogenesis in case of the two distinct viruses shows a number of common and different features. HCC usually develops in stage of liver cirrhosis caused by chronic inflammation of many years or decades. In contrast to HBC, HCV will not be incorporated into the genome of hepatocytes. It induces throughout different mechanisms the development of cancer cells, which will proliferate out of control. Before the discovery of HCV, the connection of non-A non-B (NANB) hepatitis and liver cancer has yet been observed. The subsequent epidemiological studies confirmed this association. A number of publications prove that HCC may develop without cirrhosis in HCV infected patients. The exact mechanism is not known, but data indicate that some proteins of the virus may induce oncogenic process. Differences were found in HCV core gene between HCC patients with and without cirrhosis. It is postulated that the virus evolves its oncogenic effect via endoplasmic and oxidative stress, further on by activation of different oncogenic signal pathways. Recent publications indicate the role of virus induced insulin resistance. Besides the virus determined factors, the host reaction, the deficient tumor cell eliminating capacity may also have a role in the development of liver carcinoma. Monitoring of HCV infected patients for HCC is an important clinical issue. Most relevant is the regular ultrasound cheek up. Serum alpha fetoprotein level is elevated only in a smaller proportion of the patients. The treatment protocol of HCV induced HCC does not differ from the others developed in non-HCV liver diseases.

COX-2 in liver, from regeneration to hepatocarcinogenesis: What we have learned from animal models?

The use of animals lacking genes or expressing genes under the control of cell-specific promoters has significantly increased our knowledge of the genetic and molecular basis of physiopathology, allowing testing of functional hypotheses and validation of biochemical and pharmacologic approaches in order to understand cell function. However, with unexpected frequency, gene knockout animals and, more commonly, animal models of transgenesis give experimental support to even opposite conclusions on gene function. Here we summarize what we learned on the role of cyclooxygenase 2 (COX-2) in liver and revise the results obtained in 3 independent models of mice expressing a COX-2 transgene specifically in the hepatocyte. Upon challenge with pro-inflammatory stimuli, the animals behave very differently, some transgenic models having a protective effect but others enhancing the injury. In addition, one transgene exerts differential effects on normal liver physiology depending on the transgenic animal model used.