Cyclooxygenase-2 in hepatocellular carcinoma

The emerging role of fatty acid binding protein 7 (FABP7) in cancers

Fatty acid binding protein 7 (FABP7) is an intracellular protein involved in the uptake, transportation, metabolism, and storage of fatty acids (FAs). FABP7 is upregulated up to 20-fold in multiple cancers, usually correlated with poor prognosis. FABP7 silencing or pharmacological inhibition suggest FABP7 promotes cell growth, migration, invasion, colony and spheroid formation/increased size, lipid uptake, and lipid droplet formation. Xenograft studies show that suppression of FABP7 inhibits tumour formation and tumour growth, and improves host survival. The molecular mechanisms involve promotion of FA uptake, lipid droplets, signalling [focal adhesion kinase (FAK), proto-oncogene tyrosine-protein kinase Src (Src), mitogen-activated protein kinase kinase/p-extracellular signal-regulated kinase (MEK/ERK), and Wnt/β-catenin], hypoxia-inducible factor 1-alpha (Hif1α), vascular endothelial growth factor A/prolyl 4-hydroxylase subunit alpha-1 (VEGFA/P4HA1), snail family zinc finger 1 (Snail1), and twist-related protein 1 (Twist1). The oncogenic capacity of FABP7 makes it a promising pharmacological target for future cancer treatments.

Oxyphenbutazone ameliorates carfilzomib induced cardiotoxicity in rats via inhibition of oxidative free radical burst and NF-κB/IκB-α pathway

Carfilzomib (CFZ), a chemotherapeutic agent used for multiple myeloma treatments reported to cause high incidence of cardiac events either new onset and/or exacerbate formerly diagnosed heart failure with ventricular and myocardial dysfunction. Purpose: Current research designed to explore and examine the preventive effect of oxyphenbutazone in the CFZ -instigated cardiotoxicity. Methodology: Female Wistar Rats weighing 200-250 g selected randomly and grouped as follows: Group 1 designated as the Normal control and receive normal saline only. Group 2 served toxic control and exposed to CFZ (4 mg/kg, intraperitoneally [i.p.]). Group 3 & 4 served as treatment groups and administered with CFZ concomitantly orally fed with oxyphenbutazone at doses of 35 and 70 mg/kg/three times a week, respectively. The total duration of experimental protocol was of 21 days. After completion of the experiments animals subjected to blood collection using light ether anesthesia and serum was separated for biochemical analysis further. The serum levels of Mg+2, Ca+2 and cardiac enzymes (aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase-MB (CK-MB) levels were estimated. Later animals sacrificed and heart tissue isolated for further examinations. Intracellular proteins NFkB and IkBα were estimated by western blot. Results: The serum analysis revealed that CFZ administration significantly elevated the levels of LDH, CK and CKMB in CFZ exposed animals when compared to normal animals while administration of oxyphenbutazone significantly reduced these biochemical changes, Intracellular antioxidant enzymes and NF-kB in treatment groups as compared to disease control animals. Conclusion: Findings of the research protocol suggests significant injuries to cardiac tissues when animals exposed to CFZ and Oxyphenbutazone protected the cardiac tissues.

The crosstalk between ferroptosis and anti-tumor immunity in the tumor microenvironment: molecular mechanisms and therapeutic controversy

The advent of immunotherapy has significantly reshaped the landscape of cancer treatment, greatly enhancing therapeutic outcomes for multiple types of cancer. However, only a small subset of individuals respond to it, underscoring the urgent need for new methods to improve its response rate. Ferroptosis, a recently discovered form of programmed cell death, has emerged as a promising approach for anti-tumor therapy, with targeting ferroptosis to kill tumors seen as a potentially effective strategy. Numerous studies suggest that inducing ferroptosis can synergistically enhance the effects of immunotherapy, paving the way for a promising combined treatment method in the future. Nevertheless, recent research has raised concerns about the potential negative impacts on anti-tumor immunity as a consequence of inducing ferroptosis, leading to conflicting views within the scientific community about the interplay between ferroptosis and anti-tumor immunity, thereby underscoring the necessity of a comprehensive review of the existing literature on this relationship. Previous reviews on ferroptosis have touched on related content, many focusing primarily on the promoting role of ferroptosis on anti-tumor immunity while overlooking recent evidence on the inhibitory effects of ferroptosis on immunity. Others have concentrated solely on discussing related content either from the perspective of cancer cells and ferroptosis or from immune cells and ferroptosis. Given that both cancer cells and immune cells exist in the tumor microenvironment, a one-sided discussion cannot comprehensively summarize this topic. Therefore, from the perspectives of both tumor cells and tumor-infiltrating immune cells, we systematically summarize the current conflicting views on the interplay between ferroptosis and anti-tumor immunity, intending to provide potential explanations and identify the work needed to establish a translational basis for combined ferroptosis-targeted therapy and immunotherapy in treating tumors.

PSMD4 drives progression of hepatocellular carcinoma via Akt/COX2 pathway and p53 inhibition

The ubiquitin-dependent proteolytic pathway is crucial for cellular regulation, including control of the cell cycle, differentiation, and apoptosis. Proteasome 26S Subunit Ubiquitin Receptor, Non-ATPase 4, (PSMD4) is a member of the ubiquitin proteasome family that is upregulated in multiple solid tumors, including hepatocellular carcinoma (HCC), and the existence of PSMD4 is associated with unfavorable prognosis. In this study, transcriptome sequencing of HCC tissues and non-tumor hepatic tissues from the public database Cancer Genome Atlas (TGCA) revealed a high expression of PSMD4. Additionally, PSMD4 loss in HCC cells suppressed the tumor development in mouse xenograft model. PSMD4, which is maintained by inflammatory factors secreted from tumor matrix cells, positively mediates cell growth and is associated with Akt/GSK-3β/ cyclooxygenase2 (COX2) pathway activation, inhibition of p53 promoter activity, and increased p53 degradation. However, the domain without the C-terminus (VWA+UIM1/2) sustained the activation of p53 transcription. Thus, our findings suggest that PSMD4 is involved in HCC tumor growth through COX2 expression and p53 downregulation. Therapeutic strategies targeting PSMD4 and its downstream effectors could be used for the treatment of PSMD4-abundant HCC patients.

Research progress on the utilization technology of broccoli stalk, leaf resources, and the mechanism of action of its bioactive substances

Broccoli is a nutritious vegetable. It is high in protein, minerals, and vitamins. Also, it possesses antioxidant activities and is beneficial to the human body. Due to its active effect, broccoli is widely accepted by people in daily life. However, in terms of current utilization, only its florets are consumed as vegetables, while more than half of its stalks and leaves are not utilized. The stalks and leaves contain not only nutrients but also bioactive substances with physiologically regulating properties. Therefore research into the action and mechanism of its bioactive substances as well as its development and utilization technology will make contributions to the further promotion of its resource development and utilization. As a theoretical foundation for the resource utilization of broccoli stalks and leaves, this report will review the distribution and consumption of broccoli germplasm resources, the mechanism of action of bioactive substances, and innovative methods for their exploitation.

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

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

Association of aspirin and nonaspirin NSAIDs therapy with the incidence risk of hepatocellular carcinoma: a systematic review and meta-analysis on cohort studies

According to the current research evidence, the therapy of nonsteroidal anti-inflammatory drugs (NSAIDs) might effectively decrease the risk of hepatocellular carcinoma (HCC) incidence. Investigations have been conducted on the relationship between NSAIDs (aspirin and nonaspirin NSAIDs) and the risk of HCC incidence. We searched the PubMed, Web of Science, Embase and Cochrane Library databases for cohort studies published prior to 15 March 2020 and screened eligible studies. There were a total of 12 eligible studies (published between 2012 and 2020). We observed a lower risk of HCC among aspirin users [hazard ratio 0.53; 95% confidence interval (CI), 0.43-0.65]. However, there were no statistically significant associations discovered between nonaspirin NSAID use and the risk of HCC incidence (hazard ratio 0.95; 95% CI, 0.79-1.15). Furthermore, aspirin use has also been found to reduce the risk of HCC in patients with cirrhosis or viral hepatitis compared to that in the general population (hazard ratio 0.15; 95% CI, 0.10-0.23; hazard ratio 0.65; 95% CI, 0.56-0.76, respectively). Moreover, no statistical associations were found between aspirin use and a higher risk of bleeding risk, with a hazard ratio value of 0.76 (95% CI, 0.51-1.13). In summary, the conducted meta-analysis reveals that aspirin, rather than nonaspirin NSAIDs, can significantly decrease the risk of HCC, particularly in patients with cirrhosis or viral hepatitis.

Combination therapies plus transarterial chemoembolization in hepatocellular carcinoma: a snapshot of clinical trial progress

INTRODUCTION

Unfortunately, some hepatocellular carcinoma (HCC) patients do not qualify for curative-intent treatments such as surgical resection or transplantation. Hence, locoregional treatments such as transarterial chemoembolization (TACE) remain instrumental in the treatment of HCC. Systemic therapy has improved over the past decade with the introduction of combination atezolizumab and bevacizumab as the new standard of care for advanced disease. These new therapies are currently under investigation in combination with TACE.

AREA COVERED

Combination therapies with TACE including systemic therapies, locoregional therapies, and immunotherapies are reviewed.

EXPERT OPINION

There has been limited progress in the management of advanced and intermediate HCC. Recent advances in the management of advanced disease with systemic therapy could be beneficial in combination with TACE for the treatment of intermediate stage disease. Immune based therapies are potentially beneficial in combination with TACE because TACE may produce increased antigen release and immune recognition.

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.

Circulating prostaglandin E2: a novel potential prognostic biomarker in patients with hepatocellular carcinoma

We aimed to explore the activation of monoacylglycerol lipase (MAGL)/cyclooxygenase-2 (COX-2)/prostaglandin E₂ (PGE2) axis in hepatocellular carcinoma (HCC), evaluating circulating PGE2 as prognostic biomarker in HCC patients. PGE2 levels were measured in blood samples from 24 cirrhotics, and 34 HCC patients were consecutively collected between January 2016 and December 2017. In a subgroup of patients, tissue expression of MAGL mRNA and immunohistochemistry for MAGL and COX-2 were obtained. Despite tumor tissues showing overexpression of MAGL mRNA and higher levels of both MAGL and COX-2 at immunohistochemistry, PGE2 levels were not significantly different in HCC and cirrhotics. HCC patients with circulating PGE2 levels > 14 pg/mL had a significantly shorter overall survival (19.4 vs. 49.9 months; p = 0.03), the finding being confirmed by the multivariate analysis (HR 3.37 [95% CI 1.00-11.60]; p = 0.05). The MAGL/COX-2/PGE2 axis is activated in HCC, and circulating PGE2 proved to be a potential prognostic biomarker.

Exposure to growth hormone is associated with hepatic up-regulation of cPLA2α and COX

Continuously elevated levels of growth hormone (GH) during life in mice are associated with hepatomegaly due to hepatocytes hypertrophy and hyperplasia, chronic liver inflammation, elevated levels of arachidonic acid (AA) at young ages and liver tumors development at old ages. In this work, the hepatic expression of enzymes involved in AA metabolism, cPLA2α, COX1 and COX2 enzymes, was evaluated in young and old GH-transgenic mice. Mice overexpressing GH exhibited higher hepatic expression of cPLA2α, COX1 and COX2 in comparison to controls at young and old ages and in both sexes. In old mice, when tumoral and non-tumoral tissue were compared, elevated expression of COX2 was observed in tumors. In contrast, exposure to continuous lower levels of hormone for a short period affected COX1 expression only in males. Considering the role of inflammation during liver tumorigenesis, these findings support a role of alterations in AA metabolism in GH-driven liver tumorigenesis.

Use of cyclooxygenase inhibitor and the risk of hepatocellular carcinoma in patients with chronic hepatitis B: A nested case-control study using a nationwide population-based data

The study aimed to investigate the relationship between the use of COX inhibitors and the risk of hepatocellular carcinoma (HCC) development in patients with chronic hepatitis B (CHB) using a nationwide population-based data. A nested case-control study was conducted using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) from 2002 to 2013 in Korea. We compared the use of COX inhibitors between HCC cases and matched controls by categorizing 5 groups according to the cumulative defined daily dose (cDDD, <28, 28-90, 91-180, 181-360, and >360) adjusting the use of antiviral agents. A total of 4980 patients with CHB were analysed as 996 HCC cases and 3984 matched controls. The number of COX inhibitor users (≥28 cDDD) was 358 patients (36%) and 1814 patients (45%) in the HCC group and control group, respectively. The use of COX inhibitors was significantly associated with a decreased risk of HCC development compared with nonusers (adjusted odds ratio [OR] 0.62, 95% confidence interval [CI] 0.52-0.73, P < .001). There was a dose-dependent inverse relationship between the use of COX inhibitors and the risk of HCC. The adjusted ORs were 0.75 (95% CI: 0.63-0.90), 0.41 (95% CI: 0.31-0.56), 0.38 (95% CI: 0.25-0.57) and 0.49 (95% CI: 0.31-0.79) for the 28-90, 91-180, 181-360 and >360 cDDDs, respectively (P < .01). In conclusion, the use of COX inhibitors was associated with a reduced risk of HCC in CHB. COX inhibitor may have a chemopreventive role in HCC development in patients with chronic liver disease.

Prediagnostic levels of urinary 8-epi-prostaglandin F2α and prostaglandin E2 metabolite, biomarkers of oxidative damage and inflammation, and risk of hepatocellular carcinoma

Chronic inflammation and oxidative stress play pivotal roles in the pathogenesis of hepatocellular carcinoma (HCC). We conducted a nested case-control study of 347 HCC cases and 691 matched controls within a prospective cohort of 18 244 Chinese men in Shanghai, China. The concentrations of 8-epi-prostaglandin F2α (8-epi-PGF2α), a biomarker of oxidative stress, and prostaglandin E2 (PGE2) metabolite (PGE-M), a biomarker of the inflammation mediator PGE2, were determined in baseline urine samples using validated mass spectrometry assays. 8-epi-PGF2α levels were significantly higher in HCC cases than control subjects (geometric means 0.92 versus 0.80 pmol/mg creatinine, P < 0.001). The relative risks of developing HCC for the highest relative to the lowest quartile of 8-epi-PGF2α were 2.55 (95% confidence interval = 1.62-4.01, Ptrend < 0.001). This positive 8-epi-PGF2α-HCC risk association was independent of smoking status, alcohol consumption and hepatitis B or liver cirrhosis and was present 10 years before the clinical manifestation of HCC. This study did not find any significant association between urinary PEG-M and HCC risk. This study provides direct evidence in support of the critical role of oxidative stress in the development of HCC regardless of its underlying causes.

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.

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

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

Pre-and postnatal exposition to fluorides induce changes in rats liver morphology by impairment of antioxidant defense mechanisms and COX induction

INTRODUCTION

Fluorides are common in the environment and are absorbed mostly in the stomach and gut, it can easily move through cell membranes and its accumulation can cause harmful effects in skeletal and soft tissues. One of the most important F- accumulation sites is the liver. The aim of this study was to determine whether F- can cause inflammation in rat liver by affecting the activity of antioxidant enzymes and changes in the synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2).

MATERIALS AND METHODS

An in vivo model of prenatal and postnatal exposure to sodium fluoride (NaF) was used to carry out the experiment. Animals from control group received tap water to drink, while animals exposed to F- received drinking water containing NaF, 50 mg/L. In serum and liver we analyzed F- concentration, in liver - antioxidant enzymes activity, PGE2 and TXB2 concentration and immunolocalization of COX1 and COX2 proteins were measured.

RESULTS

We observed significant changes in F- concentration only in liver. The results of this study showed that F- affects antioxidant enzymes activity, COX2 protein expression and PGE2 synthesis in liver. Also, in some regions of the liver of rats exposed to F-, the hepatocytes were diffusely altered, with changes resembling microvesicular steatosis.

CONCLUSION

Chronic exposure to F^- during development causes an accumulation of this element in the liver and changes in antioxidant enzymes activity and cyclooxygenase expression. Long term exposure to this element is toxic to the liver and can cause disturbances in its homeostasis.

Adjuvant celecoxib and lanreotide following transarterial chemoembolisation for unresectable hepatocellular carcinoma: a randomized pilot study

Recurrence of hepatocellular carcinoma (HCC) after transarterial chemoembolisation (TACE) is common due to neoangiogenesis. Cyclooxygenase-2 inhibitors and somatostatin analogues were reported to inhibit tumour angiogenesis. The pilot randomized controlled trial was aimed to prospectively evaluate the protocol of TACE combined with celecoxib and lanreotide (TACE+C+L) in patients with unresectable and advanced HCC. A total of 71 patients with HCC were enrolled and randomly assigned to either TACE (n=35) or TACE+C+L (n=36) group. Overall survival, disease control rate (DCR), and adverse events were assessed during a 3-year follow-up period. The median overall survival of the TACE+C+L group (15.0 months) was doubled compared to that of TACE group (7.5 months), p = 0.012. DCR of the TACE+C+L group was significantly higher than that of the TACE group either at 6 months (72.2% vs 42.9%, p = 0.012) or at 12 months (61.1% vs 28.6%, p = 0.006). The median overall survivals (13 months vs 4.5 months, p = 0.013) and DCR at 12 months (50% vs 13.6%, p = 0.008) of patients with advanced HCC in TACE+C+L groups were significantly higher than those in TACE group. No significant difference of adverse events was observed between the two groups. The occurrence of post-embolisation syndrome in TACE+C+L group was significantly lower than that in TACE group (16.7% vs 60.0%, p = 0.001). In conclusion, the regimen of TACE+C+L prolonged overall survival, enhanced tumour response, reduced post-embolisation syndrome and was well-tolerable in the patients with unresectable HCC. It may be more beneficial for advanced HCC.

Butaselen prevents hepatocarcinogenesis and progression through inhibiting thioredoxin reductase activity

Hepatocellular carcinoma (HCC) accounts for most of primary liver cancer, of which five-year survival rate remains low and chemoprevention has become a strategy to reduce disease burden of HCC. We aim to explore the in vivo chemopreventive effect of an organoselenium-containing compound butaselen (BS) against hepatocarcinogenesis and its underlying mechanisms. Pre- and sustained BS treatment (9, 18 and 36mg/Kg BS) could dose-dependently inhibit chronic hepatic inflammation, fibrosis, cirrhosis and HCC on murine models with 24 weeks treatment scheme. The thioredoxin reductase (TrxR), NF-κB pathway and pro-inflammatory factors were activated during hepatocarcinogenesis, while their expression were decreased by BS treatment. BS treatment could also significantly reduce tumor volume in H22-bearing models and remarkably slow tumor growth. HCC cell lines HepG2, Bel7402 and Huh7 were time- and dose-dependently inhibited by BS treatment. G2/M arrest and apoptosis were observed in HepG2 cells after BS treatment, which were mediated by TrxR/Ref-1 and NF-κB pathways inhibition. BS generated reactive oxygen species (ROS), which could be reduced by antioxidant N-acetyl-L-cysteine (NAC) and NADPH oxidase inhibitor DPI. NAC could markedly increase HepG2 cells viability. TrxR activity of HepG2 cells treated with BS were significantly decreased in parallel with proliferative inhibition. The TrxR1-knockdown HepG2 cells also exhibited low TrxR1 activity, high ROS level, relatively low proliferation rate and increased resistance to BS treatment. In conclusion, BS can prevent hepatocarcinogenesis through inhibiting chronic inflammation, cirrhosis and tumor progression. The underlying mechanisms may include TrxR activity inhibition, leading to ROS elevation, G2/M arrest and apoptosis.

Metabolomics and eicosanoid analysis identified serum biomarkers for distinguishing hepatocellular carcinoma from hepatitis B virus-related cirrhosis

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. It is a type of inflammation-related cancer that usually follows liver hepatitis that mostly caused by hepatitis B virus (HBV) in China. However, the metabolism disturbance of HCC and HBV-cirrhosis is not yet fully understood. In addition, there is little research on the relationships between inflammation mediators and HCC. In this study, we investigated serum metabolic abnormalities in HBV-cirrhosis and HCC patients through non-targeted metabolomics and targeted eicosanoid analysis. Metabolomic analysis identified 14 metabolites, i.e. malate, citrate, succinate, lysine, carnitine, proline, ornithine, serine, phenylalanine, tyrosine, arachidonic acid arabinose, galactose and uric acid are consistently altered in HBV-cirrhosis and HCC patients. Meanwhile, eicosanoid analysis uncovered several prostaglandins and leukotrienes are implicated in pathological processes in HBV-cirrhosis and HCC. Finally, these identified biomarkers possessed strong potential to distinguish and diagnose HCC from healthy controls and HBV-cirrhosis patients. This study provided a new perspective to understand the mechanism and discover probable biomarkers of HCC.

lncRNA HULC promotes the growth of hepatocellular carcinoma cells via stabilizing COX-2 protein

Highly upregulated in liver cancer (HULC), a lncRNA overexpressed in hepatocellular carcinoma (HCC), has been demonstrated to be involved in the carcinogenesis and progression of HCC. However, the mechanisms of HULC promoting the abnormal growth of HCC cells are still not well elucidated. In the present study, we for the first time demonstrated that HULC promoted the growth of HCC cells through elevating COX-2 protein. Moreover, the study of the corresponding mechanism by which HULC upregulated COX-2 showed that HULC enhanced the level of ubiquitin-specific peptidase 22 (USP22), which decreased ubiquitin-mediated degradation of COX-2 protein by removing the conjugated polyubiquitin chains from COX-2 and finally stabilized COX2 protein. In addition, knockdown of USP22 or COX-2 attenuated HULC-mediated abnormal growth of HCC cells. In conclusion, our results demonstrated that "USP22/COX-2" axis played an important role in HULC promoting growth of HCC cells. The identification of this novel pathway may pave a road for developing new potential anti-HCC strategies.

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.

Guggulsterone sensitized drug-resistant human hepatocarcinoma cells to doxorubicin through a Cox-2/P-gp dependent pathway

Previous researches indicated that cyclooxygenase-2 (Cox-2) might be involved in P-glycoprotein (P-gp)-mediated multidrug resistance in hepatocellular carcinoma cells. Doxorubicin-resistant hepatocellular carcinoma PLC/PRF/5 cells (PLC/PRF/5R) and HepG2 (HepG2R) cells were developed in the present study. The modulatory effect of guggulsterone on Cox-2 and P-gp in PLC/PRF/5R and HepG2R cells was investigated. Cells proliferation, Cox-2 and P-gp expression, and prostaglandin E₂ release were examined using MTT, flow cytometry, western blot and ELISA assays. Small interfering RNA (siRNA) targeted against Cox-2 and multidrug resistance protein (Mdr-1) was used to regulate the expression of Cox-2 and P-gp. The results showed that co-administration of guggulsterone resulted in a significant increase in chemo-sensitivity of PLC/PRF/5R cells to doxorubicin, as compared with doxorubicin treatment alone. When doxorubicin (10µM) was combined with guggulsterone (50µM), the mean apoptotic population of PLC/PRF/5R cells was 20.16%. It was increased by 1.5 times, as compared with doxorubicin (10µM) treatment alone. Furthermore, guggulsterone had significantly inhibitory effect on the levels of Cox-2, P-gp and prostaglandin E₂. However, guggulsterone did not show significantly inhibitory effect on the expression of prostaglandin E receptors. In addition, Cox-2 siRNA simultaneously reduced the expression of Cox-2 and P-gp in PLC/PRF/5R cells. Mdr-1 siRNA had no influence on Cox-2, but inhibited P-gp expression. The present study suggested that guggulsterone might enhance the cytotoxic effect of doxorubicin to PLC/PRF/5R cells through a Cox-2/P-gp dependent pathway.

Cyclooxygenase-2 induced β1-integrin expression in NSCLC and promoted cell invasion via the EP1/MAPK/E2F-1/FoxC2 signal pathway

Cyclooxygenase-2 (COX-2) has been implicated in cell invasion in non-small-cell lung cancer (NSCLC). However, the mechanism is unclear. The present study investigated the effect of COX-2 on β1-integrin expression and cell invasion in NSCLC. COX-2 and β1-integrin were co-expressed in NSCLC tissues. COX-2 overexpression or Prostaglandin E2 (PGE2) treatment increased β1-integrin expression in NSCLC cell lines. β1-integrin silencing suppressed COX-2-mediated tumour growth and cancer cell invasion in vivo and in vitro. Prostaglandin E Receptor EP1 transfection or treatment with EP1 agonist mimicked the effect of PGE₂ treatment. EP1 siRNA blocked PGE₂-mediated β1-integrin expression. EP1 agonist treatment promoted Erk1/2, p38 phosphorylation and E2F-1 expression. MEK1/2 and p38 inhibitors suppressed EP1-mediated β1-integrin expression. E2F-1 silencing suppressed EP1-mediated FoxC2 and β1-integrin upregulation. ChIP and Luciferase Reporter assays identified that EP1 agonist treatment induced E2F-1 binding to FoxC2 promotor directly and improved FoxC2 transcription. FoxC2 siRNA suppressed β1-integrin expression and EP1-mediated cell invasion. Immunohistochemistry showed E2F-1, FoxC2, and EP1R were all highly expressed in the NSCLC cases. This study suggested that COX-2 upregulates β1-integrin expression and cell invasion in NSCLC by activating the MAPK/E2F-1 signalling pathway. Targeting the COX-2/EP1/PKC/MAPK/E2F-1/FoxC2/β1-integrin pathway might represent a new therapeutic strategy for the prevention and treatment of this cancer.

Microsomal prostaglandin E synthase-1 protects against Fas-induced liver injury

Microsomal prostaglandin E synthase-1 (mPGES-1) is the terminal enzyme for the synthesis of prostaglandin E2 (PGE2), a proproliferative and antiapoptotic lipid molecule important for tissue regeneration and injury repair. In this study, we developed transgenic (Tg) mice with targeted expression of mPGES-1 in the liver to assess Fas-induced hepatocyte apoptosis and acute liver injury. Compared with wild-type (WT) mice, the mPGES-1 Tg mice showed less liver hemorrhage, lower serum alanine transaminase (ALT) and aspartate transaminase (AST) levels, less hepatic necrosis/apoptosis, and lower level of caspase cascade activation after intraperitoneal injection of the anti-Fas antibody Jo2. Western blotting analysis revealed increased expression and activation of the serine/threonine kinase Akt and associated antiapoptotic molecules in the liver tissues of Jo2-treated mPGES-1 Tg mice. Pretreatment with the mPGES-1 inhibitor (MF63) or the Akt inhibitor (Akt inhibitor V) restored the susceptibility of the mPGES-1 Tg mice to Fas-induced liver injury. Our findings provide novel evidence that mPGES-1 prevents Fas-induced liver injury through activation of Akt and related signaling and suggest that induction of mPGES-1 or treatment with PGE2 may represent important therapeutic strategy for the prevention and treatment of Fas-associated liver injuries.

Elevation of ω-3 Polyunsaturated Fatty Acids Attenuates PTEN-deficiency Induced Endometrial Cancer Development through Regulation of COX-2 and PGE2 Production

Endometrial cancer is one of the most common gynecologic malignancies. Phosphatase and tensin homologue (PTEN)-mutation is frequently identified in endometrial cancer patients. Although high dietary intake of ω-3 polyunsaturated fatty acids (PUFAs) has been associated with reduced risk of endometrial cancer, the underlying mechanisms is still unknown. To this end, we evaluated the impact of ω-3 PUFAs using several endometrial cancer cellular and animal models. While ~27% and 40% of heterozygotic PTEN mutant mice developed endometrial cancer and atypical complex hyperplasia, respectively, none of the PTEN(+/-) mice developed cancer when we overexpressed an mfat-1 transgene, which allowed endogenous production of ω-3 PUFAs. Fish oil-enriched diet or expression of mfat-1 transgene significantly inhibited the growth of xenograft tumor derived from RL95-2 cells bearing a PTEN null mutation. At cellular level, ω-3 PUFAs treatment decreased the viability of RL95-2 cells, AKT phosphorylation, and cyclin D1 expression. These molecular events are primarily mediated through reduction of cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production. Exogenous PGE2 treatment completely blunted the impact of ω-3 PUFAs on endometrial cancer. Thus, we revealed the direct inhibitory effects of ω-3 PUFAs on endometrial cancer development and the underlying mechanisms involving reduction of COX-2 and PGE2.

Anti-Inflammatory and Analgesic Effects of the Marine-Derived Compound Excavatolide B Isolated from the Culture-Type Formosan Gorgonian Briareum excavatum

In recent years, several marine-derived compounds have been clinically evaluated. Diterpenes are secondary metabolites from soft coral that exhibit anti-inflammatory, anti-tumor and cytotoxic activities. In the present study, we isolated a natural diterpene product, excavatolide B, from cultured Formosan gorgonian Briareum excavatum and investigated its anti-inflammatory activities. We found that excavatolide B significantly inhibited the mRNA expression of the proinflammatory mediators, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in lipopolysaccharide (LPS)-challenged murine macrophages (RAW 264.7). We also examined the anti-inflammatory and anti-nociceptive effects of excavatolide B on intraplantar carrageenan-induced inflammatory responses. Excavatolide B was found to significantly attenuate carrageenan-induced nociceptive behaviors, mechanical allodynia, thermal hyperalgesia, weight bearing deficits and paw edema. In addition, excavatolide B inhibited iNOS, as well as the infiltration of immune cells in carrageenan-induced inflammatory paw tissue.

Prostaglandin E2 stimulates β1-integrin expression in hepatocellular carcinoma through the EP1 receptor/PKC/NF-κB pathway

Prostaglandin E₂ (PGE₂) has been implicated in cell invasion in hepatocellular carcinoma (HCC), via increased β1-integrin expression and cell migration; however, the mechanism remains unclear. PGE₂ exerts its effects via four subtypes of the E prostanoid receptor (EP receptor 1–4). The present study investigated the effect of EP1 receptor activation on β1-integrin expression and cell migration in HCC. Cell migration increased by 60% in cells treated with 17-PT-PGE₂ (EP1 agonist), which was suppressed by pretreatment with a β1-integrin polyclonal antibody. PGE₂ increased β1-integrin expression by approximately 2-fold. EP1 receptor transfection or treatment with 17-PT-PGE₂ mimicked the effect of PGE₂ treatment. EP1 siRNA blocked PGE₂-mediated β1-integrin expression. 17-PT-PGE₂ treatment induced PKC and NF-κB activation; PKC and NF-κB inhibitors suppressed 17-PT-PGE₂-mediated β1-integrin expression. FoxC2, a β1-integrin transcription factor, was also upregulated by 17-PT-PGE₂. NF-κB inhibitor suppressed 17-PT-PGE₂-mediated FoxC2 upregulation. Immunohistochemistry showed p65, FoxC2, EP1 receptor and β1-integrin were all highly expressed in the HCC cases. This study suggested that PGE₂ upregulates β1-integrin expression and cell migration in HCC cells by activating the PKC/NF-κB signaling pathway. Targeting PGE₂/EP1/PKC/NF-κB/FoxC2/β1-integrin pathway may represent a new therapeutic strategy for the prevention and treatment of this cancer.

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.

Prostaglandin E2 accelerates invasion by upregulating Snail in hepatocellular carcinoma cells

Our previous studies showed that prostaglandin E2 (PGE2) promotes hepatoma cell growth and migration, as well as invasion; however, the precise mechanism remains elusive. Snail and p65 protein levels were detected in human samples with hepatocellular carcinoma (HCC) by immunohistochemistry (IHC) staining. HCC cell lines (Huh-7 and Hep3B) were used for in vitro experiments. PGE2/Akt/NF-κB pathway was investigated in Huh-7 and Hep3B cells after treatment with PGE2, EP4 receptor (EP4R) agonist, Akt inhibitor, and NF-κB inhibitor, respectively, by real-time reverse transcription (RT)-PCR, Western blotting, and immunofluorescence (IF) staining. In vitro cell invasion assay was performed to evaluate the effect of PGE2 on tumor invasiveness. Knockdown of EP4R was carried out in Huh-7 cells through plasmid-based small interfering RNA (siRNA) approach to confirm the regulation of PGE2 on Snail by EP4R. Dual luciferase reporter assay was performed to assess Snail promoter activity in Huh-7 cell after treatment with EP4R agonist. We found that the protein levels of Snail were higher in HCC tissues than those in control and that PGE2 and EP4R agonist treatment significantly increased Snail expression in Huh-7 and Hep3B cells. EP4R agonist also profoundly promoted invasiveness of Huh-7 cells. Knockdown of the EP4R by siRNA completely blocked the PGE2-induced upregulation of Snail expression and reduced invasiveness of Huh-7 cells. We failed to find that EP4R-induced upregulation of Snail was reversed by inhibition of cAMP response element-binding protein (CREB), a canonical downstream target of EP4R. Alternatively, EP4R agonist treatment significantly increased the levels of phosphorylated EGFR and Akt both in Huh-7 and Hep3B cells. AG1478, an EGFR inhibitor, blocked the phosphorylation of Akt. The levels of phosphorylated IκB increased in Huh-7 cells after treatment with EP4R agonist for 30 min. The levels of phosphorylated p65 started to increase in Huh-7 cells treated with EP4R agonist for 4 h, and p65 translocated into the nucleus. In EP4R-agonist-treated Hep3B, the levels of phosphorylated p65 were also increased compared to the control group. The phosphorylation levels of p65 were significantly decreased in Huh-7 and Hep3B cells after treatment with the Akt signaling inhibitor LY294002 and EP4R agonist for 24 h. Treatment with the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) at 10 μM for 24 h blocked EP4R-agonist-induced Snail upregulation in Huh-7 and Hep3B cells. Furthermore, we obtained human Snail promoter sequence from TRED-Promoter Database and identified a putative binding site of NF-κB in the sequence through TFSEARCH analysis. Subsequently, we treated Huh-7 cells with EP4R agonist or EP4R agonist and PDTC (NF-κB antagonist) and found significantly increased Snail promoter activity after EP4R agonist treatment for 12 h. The increased Snail promoter activity could be partially abolished by additional PDTC treatment. In addition, p65 protein levels were found increased together with Snail in HCC tissues compared to normal liver tissues. In conclusion, PGE2 activates Akt/NF-κB signaling and then upregulates Snail via the EP4R/EGFR to promote migration and invasion in hepatoma cells. These findings may help future evaluation of novel chemo-preventive strategies for HCC.

Correlation of microRNA-16, microRNA-21 and microRNA-101 expression with cyclooxygenase-2 expression and angiogenic factors in cirrhotic and noncirrhotic human hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a classical example of inflammation-linked cancer and is characterized by hypervascularity suggesting rich angiogenesis. Cycloxygenase-2 (COX-2) is a potent mediator of inflammation and is considered to upregulate angiogenesis. The aims of the study are (1) to analyze expression of Cox-2 mRNA, Cox-2 protein, miR-16, miR-21 and miR-101 in HCC and adjacent liver parenchyma in cirrhotic and noncirrhotic liver, (2) to investigate the relation between COX-2 expression, miR-21 expression and angiogenic factors in these tissues and (3) to investigate the association between miR-16 and miR-101 and COX-2 expression.

METHODS

Tissue samples of HCC and adjacent liver parenchyma of 21 noncirrhotic livers and 20 cirrhotic livers were analyzed for COX-2 expression at the mRNA level (qRT-PCR) and at the protein level by Western blot and immunohistochemistry. Gene expression of VEGFA, VEGFR1, VEGFR2, Ang-1, Ang-2 and Tie-2 were correlated with COX-2 levels. miR-16, miR-21 and miR-101 gene expression levels were quantified in HCC tumor tissue.

RESULTS

COX-2 mRNA and protein levels were lower in HCC as compared to adjacent liver parenchyma both in cirrhotic and noncirrhotic liver. COX-2 protein localized mainly in vascular and sinusoidal endothelial cells and in Kupffer cells. At the mRNA level but not at the protein level, COX-2 correlated with mRNA levels of angiogenic factors VEGFR1, Ang-1, and Tie2. miR-21 expression was higher in cirrhotic tissues versus noncirrhotic tissues. MiR-101 expression was lower in cirrhotic versus noncirrhotic adjacent liver parenchyma. None of the miRNAs correlelated with COX-2 expression. miR-21 correlated negatively with Tie-2 receptor in adjacent liver parenchyma.

CONCLUSIONS

In human HCC, COX-2 mRNA but not COX-2 protein levels are associated with expression levels of angiogenic factors. MiR-21 levels are not associated with angiogenic molecules. MiR-16 and miR-101 levels do not correlate with COX-2 mRNA and protein levels.

miR-21 targets 15-PGDH and promotes cholangiocarcinoma growth

miRNAs are a group of small, noncoding RNAs that modulate the translation of genes by binding to specific target sites in the target mRNA. This study investigated the biologic function and molecular mechanism of miR-21 in human cholangiocarcinoma. In situ hybridization analysis of human cholangiocarcinoma specimens showed increased miR-21 in cholangiocarcinoma tissue compared with the noncancerous biliary epithelium. Lentiviral transduction of miR-21 enhanced human cholangiocarcinoma cell growth and clonogenic efficiency in vitro, whereas inhibition of miR-21 decreased these parameters. Overexpression of miR-21 also promoted cholangiocarcinoma growth using an in vivo xenograft model system. The NAD(+)-linked 15-hydroxyprostaglandin dehydrogenase (15-PGDH/HPGD), a key enzyme that converts the protumorigenic prostaglandin E2 (PGE2) to its biologically inactive metabolite, was identified as a direct target of miR-21 in cholangiocarcinoma cells. In parallel, cyclooxygenase-2 (COX2) overexpression and PGE2 treatment increased miR-21 levels and enhanced miR-21 promoter activity in human cholangiocarcinoma cells.

IMPLICATIONS

Cholangiocarcinogenesis and tumor progression are regulated by a novel interplay between COX-2/PGE2 and miR-21 signaling, which converges at 15-PGDH.

Prostaglandin E₂ receptor EP2 mediates Snail expression in hepatocellular carcinoma cells

Prostaglandin E2 (PGE2) has been shown to influence cell invasion and metastasis in several types of cancer, including hepatocellular carcinoma (HCC). however, the molecular mechanisms underlying it remain to be further elucidated. Snail, as one of key inducers of epithelial-mesenchymal transition (EMT), plays pivotal roles in HCC invasion and metastasis. The present study was designed to evaluate the possible signaling pathways through which PGE2 regulates Snail protein expression in HCC cell lines. PGE2 markedly enhanced Huh-7 cell invasion and migration ability by upregulating the expression level of Snail protein, and EP2 receptor played an important role in this process. Src, EGFR, Akt and mTOR were all activated and involved in the regulation of snail protein expression. Our findings suggest that PGE2 could upregulate the expression level of Snail protein through the EP2/Src/EGFR/Akt/mTOR pathway in Huh-7 cells, which promotes HCC cell invasion and migration.

Mitochondria protection with ginkgolide B-loaded polymeric nanocapsules prevents diethylnitrosamine-induced hepatocarcinoma in rats

Aim: Hepatocellular carcinoma (HCC) has no successful pharmacotherapeutic remedy. The aim of this study was to ascertain whether ginkgolide B (GB)-loaded polymeric nanocapsules can prevent diethylnitrosamine (DEN)-induced HCC in rats. Materials & methods: GB was fabricated in two types of nanocapsules of which one was polyethylene glycol coated (N1GB) and the other was uncoated (N2GB). These nanocapsules were orally gavaged during DEN-induced HCC development in rats. Results: Nanocapsulation of GB enabled aqueous suspension and slow time-dependent release of the compound. Anticarcinogenic potential of N2GB was reflected by its ability in the management of DEN-induced reactive oxygen species generation, mitochondrial dysfunction, p53, NF-κB, inducible nitric oxide synthase, COX-2 and VEGF expressions, and induction of apoptosis in cancer cells in the rat liver. Conclusion: Positive zeta-potential on N2GB surface might have offered higher hepatic accumulation of GB, especially at the electron-dense organelle mitochondria. Mitochondria protection against DEN-induced oxidative damage ensured HCC prevention.

Original submitted 27 June 2012; Revised submitted 4 December 2012; Published online 7 June 2013

Prostaglandin E2 promotes hepatocellular carcinoma cell invasion through upregulation of YB-1 protein expression

Prostaglandin E2 (PGE2) has been implicated in hepatocellular carcinoma cell invasion. Recently, it was reported that Y box-binding protein 1 (YB-1) is closely correlated with malignancy. This study was designed to examine the mechanisms by which PGE2 increases YB-1 expression and promotes HCC cell invasion. PGE2 greatly enhanced HCC cell invasion through upregulation of the YB-1 protein, and the EP1 receptor is mainly responsible for this regulation. Src and EGFR were both activated by PGE2, which in turn increased the phosphorylation levels of p44/42 MAPK. Src, EGFR and p44/42 MAPK were all involved in PGE2-induced YB-1 expression. Chemical inhibitors and RNAi analysis all confirmed the role of mTOR complex 1 in YB-1 expression induced by PGE2. Furthermore, YB-1 was able to regulate the expression of a series of EMT-associated genes, which indicated that YB-1 could have the potential to control the epithelial-mesenchymal transition process in HCC cells. These findings reveal that PGE2 upregulated YB-1 expression through the EP1/Src/EGFR/p44/42 MAPK/mTOR pathway, which greatly enhanced HCC cell invasion. This study for the first time describes the mechanisms through which PGE2 regulates YB-1 expression and promotes HCC cell invasion.

Multiple interactive factors in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer and the third most frequent cause of cancer mortality globally. Each year there are approximately 630,000 new cases of HCC in the world and more than half of the new cases occur in China. Major risk factors of HCC include HBV or HCV infection, alcoholic liver disease, and nonalcoholic fatty liver disease. Most of these risk factors lead to chronic hepatitis and cirrhosis, which is present in 80-90% of HCC patients. Hepatocarcinogenesis has been regarded as a multi-stage process involving multiple genetic or environmental factors. Interaction and cross-regulation of distinct factors synergistically contributes to HCC occurrence. A comprehensive knowledge on the multiple factors and their interaction in hepatocarcinogenesis is necessary to improve the effectiveness of HCC intervention. In this review, we will focus on the recent progress made in understanding the mechanisms of hepatocarcinogenesis and discuss some potential issues or challenges in this area.

Enhanced 5-fluorouracil cytotoxicity in high COX-2 expressing hepatocellular carcinoma cells by wogonin via the PI3K/Akt pathway

Combination therapies may increase the antitumor effects and reduce the adverse effects for the treatment of hepatocellular carcinoma. In this study, we determined the effects of 5-fluorouracil alone or in combination with wogonin in vitro and in vivo, and we investigated the possible mechanisms. The combination of these 2 drugs led to a decrease in survival and a significant synergistic inhibitory effect on high COX-2 expression in SMMC-7721 hepatocellular carcinoma (HCC) cells. Furthermore, the results show that this combination inhibits COX-2 expression and increases sensitivity to chemotherapeutic agents partly through regulating the PI3K/Akt signaling pathway. Moreover, the combination treatment caused a significant growth inhibition of human tumor xenografts in vivo. In conclusion, wogonin may increase the cytotoxicity of some antineoplastic agents and it can be used in combination with these agents as a novel therapeutic regimen for HCC treatment.

Tissue metabolomics of hepatocellular carcinoma: tumor energy metabolism and the role of transcriptomic classification

Hepatocellular carcinoma (HCC) is one of the commonest causes of death from cancer. A plethora of metabolomic investigations of HCC have yielded molecules in biofluids that are both up- and down-regulated but no real consensus has emerged regarding exploitable biomarkers for early detection of HCC. We report here a different approach, a combined transcriptomics and metabolomics study of energy metabolism in HCC. A panel of 31 pairs of HCC tumors and corresponding nontumor liver tissues from the same patients was investigated by gas chromatography-mass spectrometry (GCMS)-based metabolomics. HCC was characterized by ∼2-fold depletion of glucose, glycerol 3- and 2-phosphate, malate, alanine, myo-inositol, and linoleic acid. Data are consistent with a metabolic remodeling involving a 4-fold increase in glycolysis over mitochondrial oxidative phosphorylation. A second panel of 59 HCC that had been typed by transcriptomics and classified in G1 to G6 subgroups was also subjected to GCMS tissue metabolomics. No differences in glucose, lactate, alanine, glycerol 3-phosphate, malate, myo-inositol, or stearic acid tissue concentrations were found, suggesting that the Wnt/β-catenin pathway activated by CTNNB1 mutation in subgroups G5 and G6 did not exhibit specific metabolic remodeling. However, subgroup G1 had markedly reduced tissue concentrations of 1-stearoylglycerol, 1-palmitoylglycerol, and palmitic acid, suggesting that the high serum α-fetoprotein phenotype of G1, associated with the known overexpression of lipid catabolic enzymes, could be detected through metabolomics as increased lipid catabolism.

CONCLUSION

Tissue metabolomics yielded precise biochemical information regarding HCC tumor metabolic remodeling from mitochondrial oxidation to aerobic glycolysis and the impact of molecular subtypes on this process.

15-PGDH inhibits hepatocellular carcinoma growth through 15-keto-PGE2/PPARγ-mediated activation of p21WAF1/Cip1

15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a key enzyme in prostaglandin metabolism. This study provides important evidence for inhibition of hepatocellular carcinoma (HCC) growth by 15-PGDH through the 15-keto-PGE₂/PPARγ/p21^WAF1/Cip1 signaling pathway. Forced overexpression of 15-PGDH inhibited HCC cell growth in vitro, whereas knockdown of 15-PGDH enhanced tumor growth parameters. In a tumor xenograft model in SCID mice, inoculation of human HCC cells (Huh7) with overexpression of 15-PGDH led to significant inhibition of tumor growth, while knockdown of 15-PGDH enhanced tumor growth. In a separate tumor xenograft model in which mouse HCC cells (Hepa1-6) were inoculated into syngeneic C57BL/6 mice, intratumoral injection of adenovirus vector expressing 15-PGDH (pAd-15-PGDH) significantly inhibited xenograft tumor growth. The anti-tumor effect of 15-PGDH is mediated through its enzymatic product, 15-keto-PGE₂, which serves as an endogenous PPARγ ligand. Activation of PPARγ by 15-PGDH-derived 15-keto-PGE₂ enhanced the association of PPARγ with the p21^WAF1/Cip1 promoter and increased p21 expression and association with CDK2, CDK4 and PCNA. Depletion of p21 by shRNA reversed 15-PGDH-induced inhibition of HCC cell growth; overexpression of p21 prevented 15-PGDH knockdown-induced tumor cell growth. These results demonstrate a key 15-PGDH/15-keto-PGE₂-mediated activation of PPARγ and p21^WAF1/Cip1 signaling cascade that regulates hepatocarcinogenesis and tumor progression.

Synthesis and characterization of celecoxib derivatives as possible anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV agents

A series of novel N-(3-substituted aryl/alkyl-4-oxo-1,3-thiazolidin-2-ylidene)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamides 2a-e were synthesized by the addition of ethyl a-bromoacetate and anhydrous sodium acetate in dry ethanol to N-(substituted aryl/alkylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoro-methyl)-1H-pyrazol-1-yl]benzene sulfonamides 1a-e, which were synthesized by the reaction of alkyl/aryl isothiocyanates with celecoxib. The structures of the isolated products were determined by spectral methods and their anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV NS5B RNA-dependent RNA polymerase (RdRp) activities evaluated. The compounds were also tested for gastric toxicity and selected compound 1a was screened for its anticancer activity against 60 human tumor cell lines. These investigations revealed that compound 1a exhibited anti-inflammatory and analgesic activities and further did not cause tissue damage in liver, kidney, colon and brain compared to untreated controls or celecoxib. Compounds 1c and 1d displayed modest inhibition of HCV NS5B RdRp activity. In conclusion, N-(ethylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (1a) may have the potential to be developed into a therapeutic agent.

Prostaglandin E₂ receptor EP1-mediated phosphorylation of focal adhesion kinase enhances cell adhesion and migration in hepatocellular carcinoma cells

The prostaglandin E₂ (PGE₂) EP1 receptor has been implicated in hepatocellular carcinoma (HCC) cell invasion. However, little is known about the mechanisms of EP1 receptor-mediated cell adhesion and migration. We previously showed that PGE₂ promotes cell adhesion and migration by activating focal adhesion kinase (FAK). The present study was designed to elucidate the association between the EP1 receptor and FAK activation in HCC cells and to investigate the related signaling pathways. The effects of PGE₂, EP1 agonist 17-phenyl trinor-PGE₂ (17-PT-PGE₂), PKC and EGFR inhibitors on FAK activation were investigated by treatment of Huh-7 cells. Phosphorylation of FAK Y397 and c-Src Y416 was investigated by western blotting. Cell adhesion and migration were analyzed by WST and transwell assays, respectively. Protein kinase C (PKC) activity was measured with a PKC assay kit. The results showed that 17-PT-PGE₂ (3 µM) increased FAK Y397 phosphorylation by more than 2-fold and promoted cell adhesion and migration in Huh-7 cells. In transfected 293 cells, expression of the EP1 receptor was confirmed to upregulate FAK phosphorylation, while the EP1 receptor antagonist sc-19220 decreased PGE₂-mediated FAK activation. PKC activity and c-Src Y416 phosphorylation were enhanced after 17-PT-PGE₂ treatment. Both PKC and c-Src inhibitor suppressed the 17-PT-PGE₂-upregulated FAK phosphorylation, as well as 17-PT-PGE₂-induced cell adhesion and migration. In addition, exogenous epidermal growth factor (EGF) treatment increased FAK phosphorylation. The EGF receptor (EGFR) inhibitor also suppressed 17-PT-PGE₂-upregulated FAK phosphorylation. Our study suggests that the PGE₂ EP1 receptor regulates FAK phosphorylation by activating the PKC/c-Src and EGFR signal pathways, which may coordinately regulate adhesion and migration in HCC.

Design, Synthesis, and Evaluation of New Tripeptides as COX-2 Inhibitors

Cyclooxygenase (COX) is a key enzyme in the biosynthetic pathway leading to the formation of prostaglandins, which are mediators of inflammation. It exists mainly in two isoforms COX-1 and COX-2. The conventional nonsteroidal anti-inflammatory drugs (NSAIDs) have gastrointestinal side effects because they inhibit both isoforms. Recent data demonstrate that the overexpression of these enzymes, and in particular of cyclooxygenases-2, promotes multiple events involved in tumorigenesis; in addition, numerous studies show that the inhibition of cyclooxygenases-2 can delay or prevent certain forms of cancer. Agents that inhibit COX-2 while sparing COX-1 represent a new attractive therapeutic development and offer a new perspective for a further use of COX-2 inhibitors. The present study extends the evaluation of the COX activity to all 20(3) possible natural tripeptide sequences following a rational approach consisting in molecular modeling, synthesis, and biological tests. Based on data obtained from virtual screening, only those peptides with better profile of affinity have been selected and classified into two groups called S and E. Our results suggest that these novel compounds may have potential as structural templates for the design and subsequent development of the new selective COX-2 inhibitors drugs.

Octreotide and celecoxib synergistically encapsulate VX2 hepatic allografts following transcatheter arterial embolisation

To evaluate the encapsulation of VX2 hepatic allografts in rabbits induced by octreotide and celecoxib administration following transcatheter arterial embolisation (TAE), rabbits with hepatic VX2 allografts were divided into four groups: control, TAE, octreotide + celecoxib (O+C) and the multimodality therapy (TAE+O+C). Allograft metastasis, capsule thickness and percentage of clear cells were measured and vascular endothelial growth factor (VEGF) and CD31 were detected by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) analysis. The extrahepatic metastases of each intervention group were significantly fewer than those of the control group, with the TAE+O+C group exhibiting the fewest extrahepatic metastases. The TAE+O+C group had the greatest proportion of clear cells and thickest capsule on day 30. Increased capsule thickness was negatively correlated with tumour metastasis. In addition, VEGF expression levels assessed by immunohistochemistry and RT-PCR in the three intervention groups were significantly lower than those in the control group. Furthermore, the TAE+O+C group had a significantly reduced CD31 count induced by TAE. These results demonstrate that TAE, followed by long-term administration of octreotide and celecoxib, synergistically inhibits VX2 hepatic allograft metastasis by increasing the proportion of clear cells, promoting encapsulation and inhibiting angiogenesis.

Transcatheter arterial embolization followed by octreotide and celecoxib synergistically prolongs survival of rabbits with hepatic VX2 allografts

OBJECTIVE

To validate the efficacy of an innovative multimodality therapy with transcatheter arterial embolization (TAE) plus octreotide and celecoxib in reducing neoangiogenesis and prolonging the survival of rabbits with hepatocellular carcinoma.

METHODS

Rabbits with hepatic VX2 allografts were divided into four groups: control group, TAE group, octreotide + celecoxib (O + C) group and the multimodality therapy (TAE + O + C) group. Survival of the rabbits was analyzed using the Kaplan-Meier method and the expression of CD31 in tumor tissues was detected by immunohistochemistry.

RESULTS

Rabbits in the TAE + O + C group lived nearly 20 days longer than those in the control group. The survival rate of the TAE + O + C group was 50% at day 80 and was the highest among the four groups (P < 0.05). No VX2 allograft-bearing rabbits in the control group lived longer than 60 days. Compared with the control group, the survival time of the other two intervention groups were not prolonged significantly (P > 0.05). The CD31 expression induced by TAE was reduced significantly in TAE + O + C group (P < 0.05). Less metastasis was detected in TAE + O + C group.

CONCLUSION

TAE followed by the long-term administration of octreotide and celecoxib can synergistically prolong the survival of rabbits with hepatic VX2 allografts by inhibiting potential neoangiogenesis, tumor growth and metastasis.