Celecoxib, a cyclooxygenase-2 inhibitor, prevents induction of liver preneoplastic lesions in rats

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.

Molecular alterations that precede the establishment of the hallmarks of cancer: An approach on the prevention of hepatocarcinogenesis

Chronic liver injury promotes the molecular alterations that precede the establishment of cancer. Usually, several decades of chronic insults are needed to develop the most common primary liver tumor known as hepatocellular carcinoma. As other cancer types, liver cancer cells are governed by a common set of rules collectively called the hallmarks of cancer. Although those rules have provided a conceptual framework for understanding the complex pathophysiology of established tumors, therapeutic options are still ineffective in advanced stages. Thus, the molecular alterations that precede the establishment of cancer remain an attractive target for therapeutic interventions. Here, we first summarize the chemopreventive interventions targeting the early liver carcinogenesis stages. After an integrative analysis on the plethora of molecular alterations regulated by anticancer agents, we then underline and discuss that two critical processes namely oxidative stress and genetic alterations, play the role of 'dirty work laborer' in the initial cell damage and drive the transformation of preneoplastic into neoplastic cells, respectively; besides, the activation of cellular senescence works as a key mechanism in attempting to prevent the onset and establishment of liver cancer. Whereas the detrimental effects of the binomial made up of oxidative stress and genetic alterations are either eliminated or reduced, senescence activation is promoted by anticancer agents. We argue that collectively, oxidative stress, genetic alterations, and senescence are key events that influence the fate of initiated cells and the establishment of the hallmarks of cancer.

Water biocatalytic effect attenuates cytochrome P450-mediated carcinogenicity of diethylnitrosamine: A computational insight

The mechanism-based mutagenicity and carcinogenicity of diethylnitrosamine (DEN) are believed to act through interactions with cytochrome P450 (P450) enzymes. DFT calculations to explore the conceivable mechanisms underlying the reaction of P450 with DEN with and without water as a biocatalyst were performed. The results shed light on the biocatalytic role of water in lowering the H-abstraction energy barriers because of the electrostatic effect driven by hydrogen bonding. Our DFT analysis revealed how metabolites are formed in the dealkylation (toxification) and denitrosation (detoxification) pathways. Also, our findings uncovered the active position of DEN vulnerable to P450 interactions. Two factors control the toxification and detoxification rates: the stability of denitrosation products and the HS rebound barrier of the α-pathway. Thus, water biocatalytic attenuation of DEN carcinogenicity was attained by stabilizing denitrosation products and slowing the α-HS rebound process. Docking and MD simulations were performed to assess the binding modes of DEN to P450's active site and to inspect the denitrosation and dealkylation processes, respectively.

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.

Decorating protein nanospheres with lactoferrin enhances oral COX-2 inhibitor/herbal therapy of hepatocellular carcinoma

Aim: Lactoferrin (LF)-targeted gliadin nanoparticles (GL-NPs) were developed for targeted oral therapy of hepatocellular carcinoma. Materials & methods: Celecoxib and diosmin were incorporated in the hydrophobic matrix of GL-NPs whose surface was decorated with LF by electrostatic interaction for binding to asialoglycoprotein receptors overexpressed by liver cancer cells. Results: Targeted GL-NPs showed enhanced cytotoxic activity and increased cellular uptake in liver tumor cells compared with nontargeted NPs. Moreover, they demonstrated superior in vivo antitumor effects including reduction in the expression levels of tumor biomarkers and induction of caspase-mediated apoptosis. Ex vivo imaging of isolated organs exhibited extensive accumulation of NPs in livers more than other organs. Conclusion: LF-targeted GL-NPs could be considered as an efficient nanoplatform for targeted oral drug delivery for liver cancer therapy.

Quantum mechanical model for the anticarcinogenic effect of extremely-low-frequency electromagnetic fields on early chemical hepatocarcinogenesis

Using the conventional Haberkorn approach, it is evaluated the recombination of the radical pair (RP) singlet spin state to study theoretically the cytoprotective effect of an extremely-low-frequency electromagnetic field (ELF-EMF) on early stages of hepatic cancer chemically induced in rats. The proposal is that ELF-EMF modulates the interconversion rate of singlet and triplet spin states of the RP populations modifying the products from the metabolization of carcinogens. Previously, we found that the daily treatment with ELF-EMF 120 Hz inhibited the number and area of preneoplastic lesions in chemical carcinogenesis. The singlet spin population is evaluated diagonalizing the spin density matrix through the Lanczos method in a radical pair mechanism (RPM). Using four values of the interchange energy, we have studied the variations over the singlet population. The low magnetic field effect as a test of the influence over the enzymatic chemical reaction is evaluated calculating the quantum yield. Through a bootstrap technique the range is found for the singlet decay rate for the process. Applying the quantum measurements concept, we addressed the impact toward hepatic cells. The result contributes to improving our understanding of the chemical carcinogenesis process affected by charged particles that damage the DNA.

Celecoxib suppresses hepatoma stemness and progression by up-regulating PTEN

Celecoxib, a COX-2 inhibitor and non-steroidal anti-inflammatory drug, can prevent several types of cancer, including hepatocellular carcinoma (HCC). Here we show that celecoxib suppressed the self-renewal and drug-pumping functions in HCC cells. Besides, celecoxib depleted CD44+/CD133+ hepatic cancer stem cells (hCSC). Prostaglandin E2 (PGE2) and CD133 overexpression did not reverse the celecoxib-induced depletion of hCSC. Also, celecoxib inhibited progression of rat Novikoff hepatoma. Moreover, a 60-day celecoxib program increased the survival rate of rats with hepatoma. Histological analysis revealed that celecoxib therapy reduced the abundance of CD44+/CD133+ hCSCs in hepatoma tissues. Besides, the hCSCs depletion was associated with elevated apoptosis and blunted proliferation and angiogenesis in hepatoma. Celecoxib therapy activated peroxisome proliferator-activated receptor γ (PPARγ) and up-regulated PTEN, thereby inhibiting Akt and disrupting hCSC expansion. PTEN gene delivery by adenovirus reduced CD44/CD133 expression in vitro and hepatoma formation in vivo. This study suggests that celecoxib suppresses cancer stemness and progression of HCC via activation of PPARγ/PTEN signaling.

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.

Cholestatic hepatitis with small duct injury associated with celecoxib

Drug-induced liver injury (DILI) is a common clinical entity but is underreported due to various reasons. Cyclooxygenase-2 inhibitors like Celecoxib have been proven to be associated with lesser incidence of adverse drug reactions compared to other nonsteroidal anti-inflammatory drugs (NSAID). However, Celecoxib has been rarely reported to be associated with cholestasis and hepatitis. We present a young Hispanic female presented with cholestatic liver chemistries who has been taking Celecoxib for 3 weeks. Extensive workup did not support diagnosis of viral, autoimmune, or metabolic liver diseases. Liver biopsy revealed findings suggestive of secondary sclerosing cholangitis. Imaging studies were negative for large duct involvement, and endoscopy ruled out inflammatory bowel disease. Liver chemistries normalized after cessation of medication. We recommend that physician should be aware of this rare complication when prescribing Celecoxib.

Antitumor activity of the selective cyclooxygenase-2 inhibitor, celecoxib, on breast cancer in Vitro and in Vivo

Background

Cyclooxygenase-2(COX-2) promotes carcinogenesis, tumor proliferation, angiogenesis, prevention of apoptosis, and immunosuppression. Meanwhile, COX-2 over-expression has been associated with tumor behavior and prognosis in several cancers. This study investigated the antitumor effects of the selective COX-2 inhibitor, Celecoxib, on breast cancer in vitro and in vivo.

Methods

Human breast cancer MCF-7 and MDA-MB-231 cells were cultured with different concentration (10, 20, 40 μmol/L) of celecoxib after 0-96 hours in vitro. MTT assay was used to determine the growth inhibition of breast cancer cells in vitro. The expression of COX-2 on mRNA was measured by real-time quantitive PCR analysis. Flow cytometry was performed to analyze the cell cycle of MCF-7 cells. Levels of PGE2 were measured by ELISA method. The in vivo therapeutic effects of celecoxib were determined using rat breast cancer chemically induced by 7,12-dimethylben anthracene (DMBA).

Results

The inhibition of proliferation of both MCF-7 and MDA-MB-231 cells in vitro by celecoxib was observerd in time and dose dependent manner. Celecoxib effectively down-regulated the expression of COX-2. The cell cycle was arrested at G0/G1, and rate of cells in S phase was obviously decreased. Levels of PGE2 were inhibited by Celecoxib. The tumor incidence rate of the celecoxib group was lower than that of the control group. In addition, the tumor latency period of the celecoxib group was longer than that of the control group.

Conclusions

Celecoxib inhibited the proliferation of breast cancer cell lines in vitro, and prevented the occurrence of rat breast cancer chemically induced by DMBA. Therefore, celecoxib exhibits an antitumor activity and seems to be effective in anti-tumor therapy.

The chemopreventive capacity of quercetin to induce programmed cell death in hepatocarcinogenesis

In this study of chemoprevention in the rat modified resistant hepatocyte model, preneoplastic cells were diminished by >60% with quercetin pretreatment compared with those rats treated with N-Diethylnitrosamine (DEN) to induce liver cancer. This decrease occurred associated with an abolished DEN-induced lipid peroxidation as well as activation of caspase 9 and increased caspase 3, as determined by increased expression of cleaved caspase 3 and 9, but not cleaved caspase 8 and increased fragmentation of Poly (ADP-ribose) polymerase (PARP) inducing apoptosis of presumed genetically injured cells, when quercetin was administered before the initiation agent.

Targeted therapy for hepatocellular carcinoma: novel agents on the horizon

Hepatocellular carcinoma (HCC) is the most common liver cancer, accounting for 90% of primary liver cancers. In the last decade it has become one of the most frequently occurring tumors worldwide and is also considered to be the most lethal of the cancer systems, accounting for approximately one third of all malignancies. Although the clinical diagnosis and management of early-stage HCC has improved significantly, HCC prognosis is still extremely poor. Furthermore, advanced HCC is a highly aggressive tumor with a poor or no response to common therapies. Therefore, new effective and well-tolerated therapy strategies are urgently needed. Targeted therapies have entered the field of anti-neoplastic treatment and are being used on their own or in combination with conventional chemotherapy drugs. Molecular-targeted therapy holds great promise in the treatment of HCC. A new therapeutic opportunity for advanced HCC is the use of sorafenib (Nexavar). On the basis of the recent large randomized phase III study, the Sorafenib HCC Assessment Randomized Protocol (SHARP), sorafenib has been approved by the FDA for the treatment of advanced HCC. Sorafenib showed to be able to significantly increase survival in patients with advanced HCC, establishing a new standard of care. Despite this promising breakthrough, patients with HCC still have a dismal prognosis, as it is currently the major cause of death in cirrhotic patients. Nevertheless, the successful results of the SHARP trial underscore the need for a comprehensive understanding of the molecular pathogenesis of this devastating disease. In this review we summarize the most important studies on the signaling pathways implicated in the pathogenesis of HCC, as well as the newest emerging drugs and their potential use in HCC management.

Anti-proliferative effect of extremely low frequency electromagnetic field on preneoplastic lesions formation in the rat liver

Background

Recently, extremely low frequency electromagnetic fields (ELF-EMF) have been studied with great interest due to their possible effects on human health. In this study, we evaluated the effect of 4.5 mT - 120 Hz ELF-EMF on the development of preneoplastic lesions in experimental hepatocarcinogenesis.

Methods

Male Fischer-344 rats were subjected to the modified resistant hepatocyte model and were exposed to 4.5 mT - 120 Hz ELF-EMF. The effects of the ELF-EMF on hepatocarcinogenesis, apoptosis, proliferation and cell cycle progression were evaluated by histochemical, TUNEL assay, caspase 3 levels, immunohistochemical and western blot analyses.

Results

The application of the ELF-EMF resulted in a decrease of more than 50% of the number and the area of γ-glutamyl transpeptidase-positive preneoplastic lesions (P = 0.01 and P = 0.03, respectively) and glutathione S-transferase placental expression (P = 0.01). The number of TUNEL-positive cells and the cleaved caspase 3 levels were unaffected; however, the proliferating cell nuclear antigen, Ki-67, and cyclin D1 expression decreased significantly (P ≤ 0.03), as compared to the sham-exposure group.

Conclusion

The application of 4.5 mT - 120 Hz ELF-EMF inhibits preneoplastic lesions chemically induced in the rat liver through the reduction of cell proliferation, without altering the apoptosis process.

Preventive effect of JTE-522, a selective cyclooxygenase-2 inhibitor, on DEN-induced hepatocarcinogenesis in rats

BACKGROUND

Chemopreventive effect of a selective cyclooxygenase-2 (COX-2) inhibitor JTE-522 on diethylnitrosamine (DEN)-induced hepatocarcinogenesis was evaluated in Wistar rats.

METHODS

Animals in the control group (G1) were injected with phosphate buffered saline (PBS), those in hepatocellular carcinoma (HCC) group (G2) were injected with DEN with regular foods for 14 weeks, and those in the treatment groups were injected with DEN for 14 weeks fed with JTE-522 for 7 (G3) and 14 weeks (G4), respectively. Proliferation and precancerous lesions were evaluated by expression levels of proliferating cell nuclear antigen (PCNA) and glutathione S-transferase-P (GST-P), respectively by immunohistochemistry and Western blot analysis. Apoptosis and oxidative stress were evaluated by TdT-mediated dUTP-biotin nick-end labeling (TUNEL) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) staining, respectively.

RESULTS

After 14 weeks of the treatment, HCC was developed in G2, G3, and G4 showing no significant differences in gross appearance and histology of the liver among the three groups. There were no significant differences in the expression levels of PCNA and numbers of TUNEL and 8-OHdG positive cells in the liver among the three groups. However, GST-P positive area was significantly suppressed in G3 and G4 compared to G2.

CONCLUSION

Our data revealed that JTE-522 had a modest inhibitory effect on hepatocarcinogenesis in rats in a manner independent of induction of apoptosis and inhibition of oxidative stress.

Anti-tumoral effect of a celecoxib low dose on a model of human medullary thyroid cancer in nude mice

BACKGROUND

Medullary thyroid carcinoma (MTC) is a C cell neoplasm secreting calcitonin (CT). Surgery remains the only treatment as MTC is resistant to radio- and chemotherapies. Anti-tumoral effects of nonsteroidal anti-inflammatory drugs have been observed in various cancers. Thus, we tested the anti-tumoral action of an nonsteroidal anti-inflammatory drug, celecoxib, on MTC development.

METHODS

We studied the expression of prostaglandin (PG) metabolism enzymes in our in vitro (TT cells) and in vivo (TT tumors) models and in human MTCs by Western blot. We checked the effect of celecoxib on xenografted subcutaneous tumors in nude mice. Celecoxib was administrated in powder food during 9 weeks from day 1 after TT cell injection. At the end of the experiment plasma CT was measured by radioimmunoassay, the number of proliferating cells in tumor tissues was detected by Ki67 immunocytochemistry and apoptotic nuclei by caspase 3 ad Bcl-2 expression and terminal-deoxynucleotidyl-transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. PGE(2) concentrations in TT cell medium were evaluated by an enzyme immunoassay kit.

RESULTS

Our in vitro and in vivo models were validated: the status of PG metabolism enzymes was comparable in these models and in human MTCs. A very low dose of celecoxib, 120 ppm in food, inhibited tumor volume by 71% and reduced plasma CT level. Although no proapoptotic effect was detectable in tumors, a decrease of proliferating cells was revealed. The inducible PG synthesis enzyme, cyclooxygenase 2, was only detectable in rare stromal cells. The expression of the constitutive PG synthesis enzyme, cyclooxygenase 1, was diminished, while the level of the catabolism enzyme, 15-PG dehydrogenase, was decreased. In vitro, TT cells treated for 12 days with 25 muM celecoxib reproduced these changes, and PGE(2) secretion was not significantly modified by the treatment, in these conditions.

CONCLUSION

Celecoxib has a good therapeutic potential for MTC to prevent metastasis growth, and its anti-tumoral effect is, at least in part, independent of PGE(2).

Celecoxib enhances the detoxification of diethylnitrosamine in rat liver cancer

AIM: To study the effect of celecoxib (CXB) on diethylnitrosamine activation through the regulation of cytochrome P450 in a hepatocarcinogenesis model.

METHODS: Six-week-old male Sprague-Dawley rats were randomly divided into five groups, a non-treated group (NT), a diethylnitrosamine-treated group (DEN), a DEN+CXB-treated group (DEN+CXB), and CXB 8 d-treated and CXB 32 d-treated groups. The effects of celecoxib on the enzymatic activities of CYP1A1, 2A, 2B1/2, and 2E1 were assessed in hepatic microsomes 24 h after DEN administration. Changes in CYP1A1 and CYP2B1/2 protein expression were also evaluated. The rate of DEN metabolism was measured by the production of the deethylation metabolite acetaldehyde, and the denitrosation metabolite nitrite.

RESULTS: DEN+CXB administration produced a significant increase in the enzymatic activities of CYP2B1/2 and 1A1, whereas it did not change the activities of CYP2A and 2E1, compared to that of the DEN group. CXB treatment for eight days did not produce a significant effect on enzymatic activity when compared to the NT group; however, when it was administered for prolonged times (CXB 32 d group), the enzymatic activities were increased in a similar pattern to those in the DEN+CXB group. The observed increase in the enzymatic activities in the DEN+CXB group was accompanied by an increase in the CYP2B1/2 protein levels; no changes were observed in the levels of CYP1A1. In vitro, CXB increased the denitrosation of DEN, a pathway of metabolic detoxification. The addition of SKF-525A, a preferential inhibitor of CYP2B, abrogated the denitrosation of DEN.

CONCLUSION: These results suggest that the mechanism of action of CXB involves enhancement of the detoxification of DEN by an increasing denitrosation via CYP2B1/2.

Advancements of cyclooxygenase inhibitor in the prevention and treatment of hepatoma

It was reported that the cyclooxygenase-2 (COX-2) and its products were over-expressed in many malignant tumors. Non-steroidal anti-inflammatory drugs (NSAIDs) can inhibit COX activity, and also can reduce proliferation, enhance apoptosis, decrease angiogenesis and invasiveness of tumor cells. Hepatoma is one of common malignancies worldwide, and its prognosis is still extremely poor and the cellular mechanisms contributing to hepatic carcinogenesis are relatively unknown. Therefore, the prevention and treatment of liver cancer are limited. At present, it is important to find new drugs and investigate their action mechanisms. This article provides a brief review on the research progress of COX inhibitor in the prevention and treatment of hepatoma.

Combined action of celecoxib and ionizing radiation in prostate cancer cells is independent of pro-apoptotic Bax

BACKGROUND AND PURPOSE

The cyclooxygenase-2-inhibitor celecoxib has been shown to inhibit cell growth and to reduce prostatic intraepithelial neoplasia in mice. The drug was suggested to increase efficacy of ionizing radiation. However, extent and mechanisms of the suggested benefit of celecoxib on the radiation response are still unclear. The aim of the present study was to analyze cytotoxic efficacy of celecoxib in combination with irradiation on human prostate cancer cell lines and to define the importance of pro-apoptotic Bax in this process.

MATERIALS AND METHODS

Induction of apoptosis and global and clonogenic cell survival upon irradation- (2-10Gy), celecoxib- (10-75microM) or combined treatment were evaluated in prostate cancer cells by fluorescence microscopy, WST-1 assay and standard colony formation assays.

RESULTS

Celecoxib <25microM caused morphological changes and growth inhibition without substantial apoptosis or radiosensitization in terms of decreased clonogenic cell survival. In contrast, celecoxib 25microM increased radiation-induced cell death and clonogenic kill. While radiation-induced clonogenic death was increased in the presence of Bax, effects of celecoxib or combined treatment were Bax independent.

CONCLUSIONS

Our findings reveal Bax-independent beneficial effects of celecoxib on radiation-induced apoptosis and eradication of clonogenic prostate cancer cells in vitro providing a rationale for clinical evaluation of high-dose celecoxib in combination with irradiation in prostate cancer patients.

Celecoxib inhibited activation of NF-kB and expression of NF-kB P65 protein in HepG2 cells

AIM: To investigate effects of COX-2 inhibitor celecoxib on activation of nuclear factor-kappa B (NF-kB) and on protein expression of NF-kB P65 in human liver cancer cell line HepG2.

METHODS: HepG2 cells were treated with various concentrations of celecoxib. The NF-kB DNA binding activation was detected using electrophoresis mobility shift assay and protein expression of NF-kB p65 was determined using western blotting in HepG2 cells.

RESULTS: After HepG2 cells were treated with different concentrations of celecoxib (25 and 50 μmol/L, respectively), NF-kB DNA binding activation were significantly reduced (t = 12.58, P = 0.000; t = 17.97, P = 0.000) and protein expression of NF-kB p65 were significantly inhibited in celecoxib-treated HepG2 cells as compared with those in the empty control group (t = 4.24, P = 0.013; P = 6.38, P = 0.003).

CONCLUSION: Activation of NF-kB and expression of NF-kB p65 protein in HepG2 cells are effectively inhibited by celecoxib.

Inhibition of cyclooxygenase-2 activity by celecoxib does not lead to radiosensitization of human prostate cancer cells in vitro

PURPOSE

To evaluate the potential radiosensitizing effect of the specific COX-2 inhibitor celecoxib (Celebrex) on prostate carcinoma cells in vitro.

MATERIALS AND METHODS

The influence of celecoxib (concentration range 5 to 75 microM) on radiation-induced cellular and clonogenic survival was investigated in prostate carcinoma cell lines PC-3, DU145, LNCaP and normal prostate epithelial cells (PrEC). Western blot analysis and ELISA were used to determine the impact of radiation alone or radiation combined with celecoxib treatment on COX-2 expression and prostaglandin E2 synthesis. To evaluate induction of celecoxib-induced apoptosis cell cycle analysis has been performed.

RESULTS

Celecoxib (5, 10 and 25 microM) in combination with single-dose irradiation of 2 Gy induced a significant radiosensitization in normal prostate epithelial cells which could not be observed for any of the prostate carcinoma cell lines investigated. Increased COX-2 protein expression in PC-3 cells was obvious only after IR with 15 Gy, while PGE2 production was elevated following irradiation (2-15 Gy) in a dose-dependent manner. Treatment with celecoxib alone or in combination with IR led to a dose-dependent increase in COX-2 protein expression. Nevertheless pre-treatment with celecoxib caused a marked reduction of radiation-induced enzyme activity as tested at the level of PGE2 production, both in PC-3 and DU145 cells. Following fractionated irradiation with single doses of 2 Gy, elevated COX-2 protein expression as well as enhanced PGE2 production was observed already after the second fraction in PC-3 cells. Pre-treatment with celecoxib reduced the amount of PGE(2) significantly, but not of COX-2 protein.

CONCLUSIONS

Our data obtained for the human prostate cancer cell lines do not indicate that a marked inhibition of prostaglandin E2 synthesis by celecoxib leads to enhanced radiosensitization. Thus, in terms of radiosensitization the analysed prostate cancer cells can be classified as non-responders to celecoxib treatment.

Gene expression profile related to the progression of preneoplastic nodules toward hepatocellular carcinoma in rats

In this study, we investigated the time course gene expression profile of preneoplastic nodules and hepatocellular carcinomas (HCC) to define the genes implicated in cancer progression in a resistant hepatocyte model. Tissues that included early nodules (1 month, ENT-1), persistent nodules (5 months, ENT-5), dissected HCC (12 months), and normal livers (NL) from adult rats were analyzed by cDNA arrays including 1185 rat genes. Differential genes were derived in each type of sample (n = 3) by statistical analysis. The relationship between samples was described in a Venn diagram for 290 genes. From these, 72 genes were shared between tissues with nodules and HCC. In addition, 35 genes with statistical significance only in HCC and with extreme ratios were identified. Differential expression of 11 genes was confirmed by comparative reverse transcription-polymerase chain reaction, whereas that of 2 genes was confirmed by immunohistochemistry. Members involved in cytochrome P450 and second-phase metabolism were downregulated, whereas genes involved in glutathione metabolism were upregulated, implicating a possible role of glutathione and oxidative regulation. We provide a gene expression profile related to the progression of nodules into HCC, which contributes to the understanding of liver cancer development and offers the prospect for chemoprevention strategies or early treatment of HCC.

Cyclooxygenases in hepatocellular carcinoma

Many epidemiological studies demonstrate that treatment with non-steroidal anti-inflammatory drugs (NSAIDs) reduce the incidence and mortality of certain malignancies, especially gastrointestinal cancer. The cyclooxygenase (COX) enzymes are well-known targets of NSAIDs. However, conventional NSAIDs non-selectively inhibit both the constitutive form COX-1, and the inducible form COX-2. Recent evidence indicates that COX-2 is an important molecular target for anticancer therapies. Its expression is undetectable in most normal tissues, and is highly induced by pro-inflammatory cytokines, mitogens, tumor promoters and growth factors. It is now well-established that COX-2 is chronically overexpressed in many premalignant, malignant, and metastastic cancers, including hepatocellular carcinoma (HCC). Overexpression of COX-2 in patients with HCC is generally higher in well-differentiated HCCs compared with less-differentiated HCCs or histologically normal liver, suggesting that COX-2 may be involved in the early stages of hepatocarcinogenesis, and increased expression of COX-2 in noncancerous liver tissue has been significantly associated with shorter disease-free survival in patients with HCC.

In tumors, overexpression of COX-2 leads to an increase in prostaglandin (PG) levels, which affect many mechanisms involved in carcinogenesis, such as angiogenesis, inhibition of apoptosis, stimulation of cell growth as well as the invasiveness and metastatic potential of tumor cells.

The availability of novel agents that selectively inhibit COX-2 (COXIB), has contributed to shedding light on the role of this molecule. Experimental studies on animal models of liver cancer have shown that NSAIDs, including both selective and non-selective COX-2 inhibitors, exert chemopreventive as well as therapeutic effects. However, the key mechanism by which COX-2 inhibitors affect HCC cell growth is as yet not fully understood.

Increasing evidence suggests the involvement of molecular targets other than COX-2 in the anti-proliferative effects of COX-2 selective inhibitors. Therefore, COX-inhibitors may use both COX-2-dependent and COX-2-independent mechanisms to mediate their antitumor properties, although their relative contributions toward the in vivo effects remain less clear.

Here we review the features of COX enzymes, the role of the expression of COX isoforms in hepatocarcinogenesis and the mechanisms by which they may contribute to HCC growth, the pharmacological properties of COX-2 selective inhibitors, the antitumor effects of COX inhibitors, and the rationale and feasibility of COX-2 inhibitors for the treatment of HCC.

Chemoprevention of spontaneous development of hepatocellular carcinomas in fatty liver Shionogi mice by a cyclooxygenase-2 inhibitor

Cyclooxygenase 2 (COX-2) and retinoid X receptor alpha (RXRalpha) are suggested to have roles in carcinogenesis. COX-2 inhibitors have been reported to suppress growth of hepatocellular carcinoma (HCC) cell lines in vitro. However, little is known about the preventive effect of these drugs on spontaneous hepatocarcinogenesis in vivo. Etodolac exists in a racemic mixture containing S- and R-etodolac. S-etodolac is responsible for COX-2 inhibitory activity and R-etodolac is related to the downregulation of RXRalpha. Here, the effect of etodolac on spontaneous development of HCC in fatty liver Shionogi mice is evaluated. Etodolac was administered at a low (2 mg/kg) or high (10 mg/kg) dose three times a week for 16 months starting at the age of 3 months. The development of HCC was suppressed slightly in the high-dose group, and suppressed markedly in the low-dose group, although the development of fatty liver was not inhibited in either group. Plasma prostaglandin E2 levels were also decreased significantly in the low-dose group, consistent with the suppression of HCC. The expression of RXRalpha and proliferating cell nuclear antigen in non-tumorous liver tissues was decreased significantly in both the low-dose and high-dose groups. These findings show that etodolac treatment at an optimum dose suppresses hepatocarcinogenesis in vivo, and may be useful for preventing the development of HCC in humans.

Cyclooxygenase-2 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer related mortality worldwide. The incidence of HCC is rising worldwide, especially in the United States. The overall survival of patients with HCC is grim and currently no efficient secondary prevention or systemic treatments are available. Recent evidence suggests that COX-2 signaling is implicated in hepatocarcinogenesis and COX-2 inhibitors prevent HCC cell growth in vitro and in animal models. However, given the recently reported side effect associated with some of the COX-2 inhibitors, it is imperative to develop chemotherapeutic strategy that simultaneously targets COX-2 and other related key molecules in hepatocarcinogenesis or to utilize agents inhibiting COX-2 signaling in conjunction with other standard chemotherapy or radiation therapy. Such combinational therapeutic approaches are expected to provide synergistic anti-tumor effect with lesser side effect. In this regard, the recently delineated interplay between COX-2-derived PG signaling and other growth-regulatory pathways such as EGFR, Met, iNOS, VEGF and n-3 polyunsaturated fatty acids is expected to provide important therapeutic implications. This review summarizes the recent advances in understanding the mechanisms for COX-2-derived PG signaling in hepatocarcinogenesis and focuses on the newly unveiled interactions between PG cascade and other key signaling pathways that coordinately regulate HCC growth. Understanding these mechanisms and interplays will facilitate the development of more effective chemopreventive and therapeutic strategies.