Suppression of metastasis by nuclear factor kappaB inhibitors in an in vivo lung metastasis model of chemically induced hepatocellular carcinoma

N-Acetylcysteine Promotes Metastatic Spread of Melanoma in Mice

Simple Summary

Malignant melanoma is a cancer derived from melanocytes, the cells that produce pigment (melanin) in the skin. It develops on the skin, but can also appear on the mucous membranes and in other locations. Melanomas are responsible for 80% of deaths related to skin cancers. In recent years, the number of cases has increased alarmingly, likely in relation to sun exposure habits. Once melanoma spreads to distant parts of the body, the 5-year survival rate is about 10%. N-acetylcysteine (NAC) is a drug with antioxidant properties, and thereby could play a role in preventing cancer. NAC is commonly used as a mucolytic in different respiratory diseases, to treat acetaminophen (Tylenol) poisoning, and is also present in different nutritional supplements. Nevertheless, the use of NAC and other antioxidants in cancer has been questioned. Here, we show that high therapeutic doses of NAC may cause metastatic spread of a malignant melanoma.

Abstract

N-acetylcysteine (NAC) is a direct Cys donor and a promoter of glutathione (GSH) synthesis. GSH regulates melanoma growth and NAC has been suggested to increase melanoma metastases in mice. We found that high therapeutic doses of NAC do not increase the growth of melanoma xenografts, but can cause metastatic spread and distant metastases. Nevertheless, this is not due to an antioxidant effect since NAC, in fact, increases the generation of reactive oxygen species in the growing metastatic melanoma. Trolox, an antioxidant vitamin E derivative, administered in vivo, decreased metastatic growth. Metastatic cells isolated from NAC-treated mice showed an increase in the nuclear translocation of Nrf2, as compared to controls. Nrf2, a master regulator of the antioxidant response, controls the expression of different antioxidant enzymes and of the γ-glutamylcysteine ligase (the rate-limiting step in GSH synthesis). Cystine uptake through the xCT cystine-glutamate antiporter (generating intracellular Cys) and the γ-glutamylcysteine ligase activity are key to control metastatic growth. This is associated to an increase in the utilization of L-Gln by the metastatic cells, another metastases promoter. Our results demonstrate the potential of NAC as an inducer of melanoma metastases spread, and suggest that caution should be taken when administering GSH promoters to cancer patients.

Establishment of rat liver cancer cell lines with different metastatic potential

The gloomy outcome of liver cancer is mainly due to the high rates of metastasis and recurrence, even after curative resection for early stage liver cancer. Our study was conducted to find the animal model suitable for the study of liver cancer metastasis. In our study, two liver cancer cells were obtained from N-nitrosodiethylamine (DEN) and N-nitrosomorpholine (NMOR) induced rats, and they were cultivated, screened and cloning cultivated. Bionomics of cells was analyzed. The results show that 2 cells had different metastatic potentiality. They were named Wrh-f2 and Wrh-s2, and they have the characteristics of Hepatocellular carcinoma cells. The bionomics of 2 cells showed: (1) The chromosome karyotype analysis showed that the mode of Wrh-f2 was 80–83 and Wrh-s2 was 55–57; (2) AFP positive cytoplasmic staining was observed in Wrh-f2 and Wrh-s2. Cytokeratin (CK) 7 and CK8 positive staining was present in Wrh-f2. CK8 positive staining was present in Wrh-s2; (3) The numbers of Wrh-f2 and Wrh-s2 that passed through the Transwells were 98 ± 12 and 55 ± 15;(4) Wrh-f2 had the significant higher colony formation (78%) than Wrh-s2(8%) (P < 0.01). (5) The animal models generated solid tumours when 2 cells were inoculated to nude mouse and rat. And Wrh-f2 developed stable pulmonary metastasis. The established cell lines with different metastatic potential showed obvious advantages over liver cancer in mimicking the biological properties of malignant liver cancer tumors. It provided a suitable model for the mechanism of liver cancer metastasis in vivo and in vitro.

Diagnostic and Prognostic Significance of Inflammatory Markers in Lung Cancer-Associated Pleural Effusions

Besides massive expression in inflammatory pleural effusions, inflammatory markers are also present in cancer-induced pleural effusions. Recent advances in cancer biology point to a role of inflammatory signaling in cancer and encourage reconsidering the diagnostic and prognostic value of inflammatory markers. Here an attempt was made to relate protein levels of inflammatory markers to underlying malignant processes in the pleural space.

Pleural effusions from lung cancer patients (n=116) were subjected to a multifactorial analysis covering 13 inflammatory markers. The composition of tumor-associated effusions was compared with that of parainflammatory pleural effusions (n=30), transudates (n=18), and serum values, and evaluated in relation to cancer origin, histology, cytology, pleural involvement, treatment history, and survival time.

Inflammatory markers were significantly expressed in pleural effusions of paraneoplastic origin when compared to transudates and most serum levels. Values in pleura-invading and metastatic tumor-associated effusions were typically higher than those of other tumors. Many markers correlated negatively with survival, most prominently IL-8 (r=–0.36, p=0.001) and VEGF (r=–0.35, p=0.001).

It appears that most inflammatory markers are highly expressed in tumor-associated pleural effusions, reflecting to some extent tumor origin and localization. Despite the lower efficacy of inflammatory markers in the differentiation between exudative pleural effusions, some inflammatory markers may represent potential prognostic markers of malignant processes in the pleural space.

Triptolide Inhibits Invasion and Tumorigenesis of Hepatocellular Carcinoma MHCC-97H Cells Through NF-κB Signaling

BACKGROUND We investigated whether the plant-derived agent triptolide (TPL) could effectively inhibit the growth and invasion of human hepatocellular carcinoma (HCC) cells. MATERIAL AND METHODS MHCC-97H cells were treated with various concentration of TPL for various times. To detect the effect of NF-κB on TPL-induced signal pathways, MHCC-97H cells were transfected with p65 siRNA or p65 cDNA, then treated with TPL. We detected cell survival and apoptosis by MTT, soft-agar colony formation assay, flow cytometry, and TUNEL assay. Cell migration and invasion was determined by Matrigel invasion and a wound-healing assay. NF-κB activity was detected by electrophoretic mobility shift assay (EMSA); MMP-9 activity was detected by ELISA. Western blot and real-time PCR (RT-PCR) assays were used to detect p65 and MMP-9 protein and mRNA expression. A subcutaneously implanted tumor model of MHCC-97H cells in nude mice was used to assess the effects of TPL on tumorigenesis in vivo. RESULTS We showed that TPL treatment significantly suppressed growth and induced apoptosis of MHCC-97H cells in a dose- and time-dependent manner in vitro. Furthermore, TPL treatment inhibited invasion in vitro and inhibited the growth and lung metastasis of MHCC-97H cells in vivo. NF-κB and MMP-9 were inactivated with TPL treatment. Overexpression of p65 restored MMP-9 activity and inhibited the TPL anti-tumor effect on MHCC-97H cells. Knockdown of p65 blocked MMP-9 activation and enhanced TPL-induced cell apoptosis and survival inhibition, and TPL inhibition of migration and invasion in vitro. CONCLUSIONS TPL treatment inhibited MHCC-97H cell growth, invasion, and metastasis in vitro and vivo, suggesting that TPL could be developed as a potential therapeutic agent for the treatment of HCC.

Reciprocal activation between ATPase inhibitory factor 1 and NF-κB drives hepatocellular carcinoma angiogenesis and metastasis

Hepatocellular carcinoma (HCC) is a highly vascularized tumor with frequent extrahepatic metastasis. Active angiogenesis and metastasis are responsible for rapid recurrence and poor survival of HCC. However, the mechanisms that contribute to tumor metastasis remain unclear. Here we evaluate the effects of ATPase inhibitory factor 1 (IF1), an inhibitor of the mitochondrial H(+)-adenosine triphosphate (ATP) synthase, on HCC angiogenesis and metastasis. We found that increased expression of IF1 in human HCC predicts poor survival and disease recurrence after surgery. Patients with HCC who have large tumors, with vascular invasion and metastasis, expressed high levels of IF1. Invasive tumors overexpressing IF1 were featured by active epithelial-mesenchymal transition (EMT) and increased angiogenesis, whereas silencing IF1 expression attenuated EMT and invasion of HCC cells. Mechanistically, IF1 promoted Snai1 and vascular endothelial growth factor (VEGF) expression by way of activating nuclear factor kappa B (NF-κB) signaling, which depended on the binding of tumor necrosis factor (TNF) receptor-associated factor 1 (TRAF1) to NF-κB-inducing kinase (NIK) and the disruption of NIK association with the TRAF2-cIAP2 complex. Suppression of the NF-κB pathway interfered with IF1-mediated EMT and invasion. Chromatin immunoprecipitation assay showed that NF-κB can bind to the Snai1 promoter and trigger its transcription. IF1 was directly transcribed by NF-κB, thus forming a positive feedback signaling loop. There was a significant correlation between IF1 expression and pp65 levels in a cohort of HCC biopsies, and the combination of these two parameters was a more powerful predictor of poor prognosis.

CONCLUSION

IF1 promotes HCC angiogenesis and metastasis by up-regulation of Snai1 and VEGF transcription, thereby providing new insight into HCC progression and IF1 function. (Hepatology 2014;60:1659-1673).

The Anticancer Properties and Apoptosis-inducing Mechanisms of Cinnamaldehyde and the Herbal Prescription Huang-Lian-Jie-Du-Tang ( Huáng Lián Jiě Dú Tang) in Human Hepatoma Cells

Hepatocellular carcinoma (HCC) has long been one of the most important causes of cancer mortality in the world. Many natural products and traditional herbal medicines have been used to treat HCC in Asian countries such as Japan, Korea, Taiwan, and China. The present review aims to describe the anticancer properties and apoptotic mechanisms of cinnamaldehyde, the bioactive ingredient isolated from cinnamon trees, and the herbal prescription Huang-Lian-Jie-Du-Tang (黃連解毒湯 Huáng Lián Jiě Dú Tang; HLJDT) against human hepatoma cells in vitro and in vivo. Implication of their treatment for the development of targeted therapy against HCC is discussed.

Understanding the Biology of Bone Sarcoma from Early Initiating Events through Late Events in Metastasis and Disease Progression

The two most common primary bone malignancies, osteosarcoma (OS), and Ewing sarcoma (ES), are both aggressive, highly metastatic cancers that most often strike teens, though both can be found in younger children and adults. Despite distinct origins and pathogenesis, both diseases share several mechanisms of progression and metastasis, including neovascularization, invasion, anoikis resistance, chemoresistance, and evasion of the immune response. Some of these processes are well-studies in more common carcinoma models, and the observation from adult diseases may be readily applied to pediatric bone sarcomas. Neovascularization, which includes angiogenesis and vasculogenesis, is a clear example of a process that is likely to be similar between carcinomas and sarcomas, since the responding cells are the same in each case. Chemoresistance mechanisms also may be similar between other cancers and the bone sarcomas. Since OS and ES are mesenchymal in origin, the process of epithelial-to-mesenchymal transition is largely absent in bone sarcomas, necessitating different approaches to study progression and metastasis in these diseases. One process that is less well-studied in bone sarcomas is dormancy, which allows micrometastatic disease to remain viable but not growing in distant sites – typically the lungs – for months or years before renewing growth to become overt metastatic disease. By understanding the basic biology of these processes, novel therapeutic strategies may be developed that could improve survival in children with OS or ES.

Aspirin minimized the pro-metastasis effect of sorafenib and improved survival by up-regulating HTATIP2 in hepatocellular carcinoma

Background & Aims

We previously demonstrated the pro-metastasis effect of sorafenib in hepatocellular carcinoma (HCC), which is mediated by down-regulation of tumor suppressor HTATIP2. The aim of the present study was to determine whether aspirin minimizes this effect and improves survival.

Methods

The effects of sorafenib, aspirin, and combined sorafenib and aspirin were observed in HCCLM3 and HepG2 xenograft nude mice. Tumor growth, intrahepatic metastasis (IHM), lung metastasis, and survival were assessed. Polymerase chain reaction (PCR) array, real-time (RT)-PCR, and Western blotting were used to examine gene expression. The anti-invasion and anti-metastasis effects of aspirin were studied in HTATIP2-knockdown and HTATIP2-overexpressing HCC cell lines. The molecular mechanism of HTATIP2 regulation by aspirin was explored.

Results

Aspirin suppressed the pro-invasion and pro-metastasis effects of sorafenib in HCC and up-regulated HTATIP2 expression. Aspirin did not inhibit the proliferation of HCC cells, but it decreased the invasiveness of HCC with lower expression of HTATIP2 and increased expression of a set of markers, indicating a mesenchymal-to-epithelial transition in tumor cells. The up-regulation of HTATPI2 expression by aspirin is most likely mediated through inhibition of cyclooxygenase (COX) 2 expression.

Conclusions

Aspirin minimized the pro-metastasis effect of sorafenib by up-regulating the tumor suppressor HTATIP2; this mechanism is mediated through inhibition of COX2.

Pentoxifylline inhibits melanoma tumor growth and angiogenesis by targeting STAT3 signaling pathway

Pentoxifylline (PTX), a phosphodiesterase inhibitor, has been shown to have anti-metastatic or anti-angiogenic activity against many human cancers. However, the underlying mechanisms are unknown. In this study, we report that, PTX at sub-toxic doses can inhibit melanoma tumor growth and angiogenesis by targeting the STAT3 signaling pathway. Despite minimal cytotoxicity against normal cells, PTX suppressed phosphorylation and DNA binding of STAT3 in a dose-dependent manner. Also, PTX inhibited phosphorylation of the upstream kinases JAK1 and JAK2 and increased the expression of pSHP2 phosphatase. Expression of various STAT3 regulated gene products, such as cylinD1, CDK6, cMyc, BclXL, and VEGF was downregulated following PTX treatment. Tumor microenvironment favours tumor growth and metastasis. PTX alters tumor microenvironment by limiting IL-6 secretion and also by disrupting VEGF-VEGFR2 autocrine/paracrine signaling. PTX treatment significantly inhibited tumor growth and angiogenesis in intra-dermal xenograft mouse model in vivo without having any visible toxicity. These findings identified STAT3 signaling as a target of PTX and have thus, augmented its potential application in the treatment of melanoma and other cancers.

Interleukin-8 (CXCL8) in tumor associated non-vascular extracellular fluids: its diagnostic and prognostic values. A review

Interleukin-8 (IL-8, CXCL8) was originally discovered as a powerful attractor and activator of polymorphonuclear leukocytes. It was soon recognized that IL-8 also affects proliferation and migration of cancer cells, tumor angiogenesis and metastasis, and that it is expressed in many cancerous cell types. IL-8 protein expression is usually increased in serum of cancer patients, but markedly higher concentrations are found in cancer-associated non-vascular extracellular fluids, such as pleural effusion, ascites and cyst fluid. Elevated concentrations of IL-8 are indicative of malignant processes also in cerebrospinal fluid, urine, saliva, interstitial fluid and cervicovaginal secretions. Higher IL-8 levels are typically found in high-grade peritumoral fluids rather than low-grade tumors and benign conditions, with the exception of inflammatory processes. In line with recent molecular biology investigations, it appears that the local IL-8 production is related to its malignant origin and to tumor progression. Hence, IL-8 in peritumoral fluid is to be taken into consideration while assessing tumor character and monitoring the tumor progression/remission status. Besides, the data here collected justify the attempts to find an IL-8-targeted inhibitory therapy

Pentoxifylline reduces tumor necrosis factor-α and HIV-induced vascular endothelial activation

Untreated HIV infection is associated with endothelial dysfunction and subsequent cardiovascular disease, likely due to both direct effects of the virus and to indirect effects of systemic inflammation on the vasculature. We have recently shown that treatment with the antiinflammatory agent pentoxifylline (PTX) improved in vivo endothelial function and reduced circulating levels of the inflammatory markers vascular cell adhesion molecule-1 (VCAM-1) and interferon-gamma-induced protein (IP-10) in HIV-infected patients. To delineate the mechanisms underlying this therapeutic effect, we tested whether clinically relevant concentrations of PTX suppress VCAM-1 or IP-10 release in cultivated human lung microvascular endothelial cells. Indeed, we found that tumor necrosis factor (TNF)-α-induced VCAM-1 was reduced with concentrations of PTX in the low nanomolar range, comparable to plasma levels in PTX-treated groups. We also investigated the effect of HIV proteins and found that HIV transactivator of transcription (HIV-Tat) and HIV-envelope-derived recombinant gp120 enhanced TNF-α-induced VCAM-1 gene expression in lung microvascular and coronary macrovascular endothelial cells, respectively. In addition, PTX and a NF-κB-specific inhibitor reduced this enhanced VCAM-1 gene induction in microvascular and macrovascular endothelial cells. These results provide novel insights in how the antiinflammatory agent PTX can directly reduce HIV-associated proinflammatory endothelial activation, which may underlie vascular dysfunction and coronary vascular diseases.

Time-selective chemoprevention of vitamin E and selenium on esophageal carcinogenesis in rats: the possible role of nuclear factor kappaB signaling pathway

Previous human intervention trial demonstrated that vitamin E (Ve) and selenium (Se) supplementation decreased esophageal cancer deaths among younger participants, but may have no effect or produce an opposite effect among older ones. In our study, we intended to mimic this human nutritional trial to determine the chemopreventive effects of Ve/Se supplementation at the early or late stage of esophageal carcinogenesis in rats. Esophageal squamous cell carcinoma (ESCC) was induced in Fischer 344 rats with N-nitrosomethylbenzylamine (NMBzA, 0.35 mg/kg BW, s.c., three times per week for 5 weeks). The rats were maintained on a modified AIN-93M diet with low levels of Ve/Se or supplemented with high levels of Ve/Se at different stages. At Week 25, the number and volume of visible tumors, the numbers of dysplasia and ESCC were significantly lower in rats of supplementation during the early stage (Group C) or during the entire experimental period (Group E), but not during the late stage (Group D). Ve/Se supplementation at the early stage also significantly decreased cell proliferation, nuclear factor kappaB (NFκB) activation, protein and mRNA expression of cyclooxygenase 2 and 5-lipoxygenase and biosynthesis of prostaglandin E2 and leukotriene B4 during the carcinogenesis of rat esophagus. Our results demonstrated that the chemopreventive efficacy of Ve/Se supplementation on NMBzA-induced esophageal cancer is time selective and that supplementation during the early stage is clearly effective but probably ineffective during the late stage of carcinogenesis. NFκB signaling pathway activation and aberrant arachidonic acid metabolism might be the underlying mechanism.

Hepatocellular carcinoma: insight from animal models

Hepatocellular carcinoma (HCC) ranks as the third most common cause of death from cancer worldwide. Although major risk factors for the development of HCC have been defined, many aspects of the evolution of hepatocellular carcinogenesis and metastasis are still unknown. Suitable animal models are, therefore, essential to promote our understanding of the molecular, cellular and pathophysiological mechanisms of HCC and for the development of new therapeutic strategies. This Review provides an overview of animal models that are relevant to HCC development, metastasis and treatment. For HCC development, this Review focuses on transgenic mouse models of HBV and HCV infection, which provide experimental evidence that viral genes could initiate or promote liver carcinogenesis. Animal models of HCC metastasis provide platforms to elucidate the mechanisms of HCC metastasis, to study the interaction between the microenvironment and HCC invasion and to conduct intervention studies. In addition, animal models have been developed to investigate the effects of new treatment modalities. The criteria for establishing ideal HCC animal models are also discussed.

Antimetastatic Action of Pentoxifylline, a Methyl Xanthine Derivative, Through its Effect on PKC Mediated Integrin Transport in B16F10 Melanoma Cells

Background

Integrins are adhesion molecules known to regulate cellular processes like adhesion, migration and proliferation. At the same time role of integrin in progress of cancer metastasis is well established, increased integrin expression is reported to be linked to high metastasis potential of cells. Pentoxifylline a methyl xanthine derivative is a potent antimetastatic agent. Studies on the mechanism of inhibition of lung homing of B16F10 melanoma cells by PTX shows that it can inhibit cell- Extracellular Matrix adhesion, cell surface integrin expression as well as Protein kinase C activity. Previous study from our laboratory have shown PTX treatment can selectively inhibit the cell surface expression of α5 integrin in B16F10 cells without affecting its total cellular protein levels. Numerous studies have documented that differences in surface expression and distribution of integrins affects metastasis. The purpose of present study is to observe the effect of PTX on cellular distribution/ redistribution of integrins and to study the underlying molecular mechanism of PTX action.

Methods

Integrin internalization and transport was observed using immunofluorescence confocal microscopy. PKC activity was determined using MBP4-14 as a substrate. Immunoprecipitation and western blotting was used to show association between PKC and α5 integrin, cell adhesion assay was performed using fibronectin/fibrinogen as substrate.

Results

Immunofluorescence studies showed that PTX treatment caused a redistribution of α5 integrins from the plasma membrane to a perinuclear compartment where it colocalized with Transferrin receptor and Rab-11 GTPase. Rate of integrin internalization and recycling showed that PTX inhibited the recycling of α5 integrins from perinuclear recycling endosomes. PTX is reported to affect kinases; here we showed that PTX inhibited total PKC activity. Association between α5β1 integrin and PKC is studied using Immunoprecipitation which show that PTX affects α5β1 integrin associated PKC activity without affecting the levels of PKC. Studying the effect of delay in integrin recycling on cell functionality showed that it affects spreading of cells on fibronectin/fibrinogen.

Conclusions

Data in the present study shows that PTX interferes with PKC activity bringing about a change in integrin distribution, and there by affecting the functionality of the cell. And this may possibly serve as one of the mechanisms for antimetastatic action of PTX.

Multifunctional doxorubicin loaded superparamagnetic iron oxide nanoparticles for chemotherapy and magnetic resonance imaging in liver cancer

To develop a drug delivery system with enhanced efficacy and minimized adverse effects, we synthesized a novel polymeric nanoparticles, (YCC-DOX) composed of poly (ethylene oxide)-trimellitic anhydride chloride-folate (PEO-TMA-FA), doxorubicin (DOX) and superparamagnetic iron oxide (Fe(3)O(4)) and folate. The efficacy of the nanoparticles was evaluated in rats and rabbits with liver cancer, in comparison with free-DOX (FD) and a commercial liposome drug, DOXIL. YCC-DOX showed the anticancer efficacy and specifically targeted folate receptor (FR)-expressing tumors, thereby increasing the bioavailability and efficacy of DOX. The relative tumor volume of the YCC-DOX group was decreased two- and four-fold compared with the FD and DOXIL groups in the rat and rabbit models, respectively. Furthermore, YCC-DOX showed higher MRI sensitivity comparable to a conventional MRI contrast agent (Resovist), even in its lower iron content. In the immunohistochemical analysis, YCC-DOX group showed the lower expression of CD34 and Ki-67, markers of angiogenesis and cell proliferation, respectively, while apoptotic cells were significantly rich in the YCC-DOX group in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. These results indicate that YCC-DOX is a promising candidate for treating liver cancer and monitoring the progress of the cancer using MRI.

Identification of genes, including the gene encoding p27Kip1, regulated by serine 276 phosphorylation of the p65 subunit of NF-kappaB

Phosphorylation of the p65 subunit of NF-kappaB is required for its transcriptional activity. Recent reports show that phosphorylation of p65 at serine 276 regulates only a subset of genes, such as those encoding IL-6, IL-8, Gro-beta, and ICAM-1. In order to identify additional genes regulated by serine 276 phosphorylation, HepG2 hepatoma cells were infected with adenoviruses encoding either wild-type p65 or the S276A mutant of p65, followed by DNA microarray analysis. The results show that mutation of serine 276 affected the expression of several genes that encode proteins involved in cell cycle regulation, signal transduction, transcription, and metabolism. Notably, expression of S276A increased the mRNA and protein level of p27, a cell cycle inhibitory protein, which led to an increased association of p27 with cdk2, and inhibition of cdk2 activity. Furthermore, while wild-type NF-kappaB is known to increase cell proliferation in a number of different cancer cell lines, our data shows that S276A inhibited cell proliferation. Evidence is mounting that NF-kappaB plays a pivotal role in oncogenesis. Therapeutic agents that regulate the phosphorylation of serine 276 and p27 gene expression, therefore, may be useful as anti-cancer agents in the future.

Effects of ginsenosides Re and Rg3 on intracellular redox state and cell proliferation in C6 glioma cells

Background

Cellular redox state is important to cell growth and death. The growth of tumor cells may be modulated by intracellular reduced glutathione/oxidized glutathione (GSH/GSSG). The present study aims to investigate the effects of ginsenosides Re and Rg3 on cellular redox state and cell proliferation in C6 glioma cells.

Methods

Cultured C6 glioma cells were exposed to various concentrations of either Rg3 or Re for 24 hours. Cell growth and death were measured by the BrdU incorporation assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay respectively. Cellular redox state was determined by free radical production using flow cytometry and GSH/GSSG using spectrofluorometry.

Results

At a sub-lethal concentration, Re suppressed cell proliferation with a significant decrease in BrdU incorporation. Re did not increase reactive oxygen species (ROS) production but increased GSH/GSSG via increased activity of gamma glutamylcystenyl synthase (γ-GCS). In contrast, Rg3 increased free radical production and reduced GSH/GSSG. The effects of Rg3 were probably due to increased activity of glutathione peroxidase (GPx).

Conclusion

Re and Rg3 alter cellular redox state of C6 glioma cells in opposite directions. Changes in cellular redox state induced by Re and Rg3 are correlated with the proliferation rates of C6 glioma cells.

Huang-lian-jie-du-tang, a traditional Chinese medicine prescription, induces cell-cycle arrest and apoptosis in human liver cancer cells in vitro and in vivo

BACKGROUND AND AIM

Huang-lian-jie-du-tang (HLJDT; Japanese name, oren-gedoku-to) is a traditional Chinese medicine prescription known to possess anti-inflammatory activity. Our study reports here for the first time the anticancer effect of HLJDT in two human liver cancer cell lines, Hep G2 and PLC/PRF/5.

METHODS

Inhibition of cell proliferation by HLJDT was measured by sodium 3'-(1-(phenylamino-carbonyl)-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT) assay. Clonogenic assay was used to elucidate the possible differences in long-term effects of HLJDT on human liver cancer cells. Cell cycle distribution was determined by flow cytometry. Apoptosis was detected using electrophoresis and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick endlabeling (TUNEL) assay. Protein expressions were determined by immunoblot assay. The activity of nuclear factor-kappa B (NF-kappaB) was determined by Trans-AM ELISA kit. In vivo tumor activity was assessed by xenograft study.

RESULTS

HLJDT significantly increased the expression of inactivated phospho-Cdc2 and phospho-Cdc25C, and decreased the levels of cyclin A, cyclin B1, Cdc2, and Cdc25C, thereby contributing to cell-cycle arrest. HLJDT increased the expression of Bax and Bak, but decreased the level of Bcl-2 and Bcl-XL, and subsequently triggered the mitochondrial apoptotic pathway. In addition, HLJDT also inhibited cell-survival signaling by enhancing the amount of IkappaBalpha in the cytoplasm, reducing the level and activity of NF-kappaB in the nucleus, and subsequently attenuating the expression of Bcl-XL in Hep G2 and PLC/PRF/5 cells(.) The inhibitory effect mediated by HLJDT on cell growth was also demonstrated in a nude mouse model, in which the liver cancer cells induced tumor xenograft shrank considerably following treatment with HLJDT.

CONCLUSIONS

Taken together, these results suggest a potential anticancer effect of HLJDT against human liver cancer cells.

Nuclear factor-kappa B signaling in skeletal muscle atrophy

Skeletal muscle atrophy/wasting is a serious complication of a wide range of diseases and conditions such as aging, disuse, AIDS, chronic obstructive pulmonary disease, space travel, muscular dystrophy, chronic heart failure, sepsis, and cancer. Emerging evidence suggests that nuclear factor-kappa B (NF-kappaB) is one of the most important signaling pathways linked to the loss of skeletal muscle mass in various physiological and pathophysiological conditions. Activation of NF-kappaB in skeletal muscle leads to degradation of specific muscle proteins, induces inflammation and fibrosis, and blocks the regeneration of myofibers after injury/atrophy. Recent studies employing genetic mouse models have provided strong evidence that NF-kappaB can serve as an important molecular target for the prevention of skeletal muscle loss. In this article, we have outlined the current understanding regarding the role of NF-kappaB in skeletal muscle with particular reference to different models of muscle wasting and the development of novel therapy.

Pravastatin reduces lung metastasis of rat hepatocellular carcinoma via a coordinated decrease of MMP expression and activity

BACKGROUND/AIMS

Statins have beneficial effects in early pre-clinical models of hepatocellular carcinoma (HCC). Our aim was to test the efficacy of pravastatin on the progression of established HCC in rat, and to study its mechanisms.

METHODS

HCC was induced with diethylnitrosamine and N-nitrosomorpholine. After 14 weeks, all rats developed HCC and then received pravastatin or its solvent for 10 weeks (10 rats/group).

RESULTS

Liver tumor mass was lower in pravastatin group (PG) than control group (CG), as estimated from the number of liver tumors (p<0.004) and the liver weight/body weight ratio (p<0.04). Every CG rat surviving at 24 weeks (4/4) had lung metastasis, against only 5/8 in PG. Moreover, the percentage of lung surface occupied by metastasis was 10-fold smaller in PG than CG (p<0.016). Pravastatin decreased liver matrix metalloproteinase (MMP)-9 activity and mostly suppressed MMP-2 activation (p<0.004), likely because it decreased expression of MMP-14 and tissue inhibitor of matrix metalloproteinases-2 (p<0.01), required for MMP-2 activation.

CONCLUSIONS

Pravastatin reduces progression and limits metastatic diffusion of established HCC. This could be linked to the decreased MMP activity. These results, obtained in a very aggressive HCC model, further suggest the potential benefit of statins in human HCC.

Toward a core nutraceutical program for cancer management

As previously suggested, it may be feasible to impede tumorevoked angiogenesis with a nutraceutical program composed of glycine, fish oil, epigallocatechin-3-gallate, selenium, and silymarin, complemented by a low-fat vegan diet, exercise training, and, if feasible, a salicylate and the drug tetrathiomolybdate. It is now proposed that the scope of this program be expanded to address additional common needs of cancer patients: blocking the process of metastasis; boosting the cytotoxic capacity of innate immune defenses (natural killer [NK] cells); preventing cachexia, thromboembolism, and tumor-induced osteolysis; and maintaining optimal micronutrient status. Modified citrus pectin, a galectin-3 antagonist, has impressive antimetastatic potential. Mushroombeta-glucans and probiotic lactobacilli can amplify NK activity via stimulatory effects on macrophages. Selenium, beta-carotene, and glutamine can also increase the number and/or cytotoxic activity of NK cells. Cachectic loss of muscle mass can be opposed by fish oil, glutamine, and beta-hydroxy-beta-methylbutyrate. Fish oil, policosanol, and vitamin D may have potential for control of osteolysis. High-dose aspirin or salicylates, by preventing NF-B activation, can be expected to aid prevention of metastasis and cachexia while down-regulating osteolysis, but their impacts on innate immune defenses will not be entirely favorable. A nutritional insurance formula crafted for the special needs of cancer patients can be included in this regimen. To minimize patient inconvenience, this complex core nutraceutical program could be configured as an oil product, a powder, and a capsule product, with the nutritional insurance formula provided in tablets. It would be of interest to test this program in nude mouse xenograft models.

In vitro induction of apoptosis in U937 cells by perillyl alcohol with sensitization by pentoxifylline: increased BCL-2 and BAX protein expression

BACKGROUND

Chemotherapy is effective against a wide variety of tumor cells, although its use is limited by side effects. In vitro experiments and phase I and II trials have shown that phytochemicals such as perillyl alcohol (P-OH) have antitumor effects. Pentoxifylline (PTX), a synthetic methylxanthine used mainly to treat pathologies associated with hematological diseases, sensitizes tumor cells to chemotherapy. The aim of this study was to determine whether PTX amplifies the antitumor effects of P-OH in U937 human myelomonocytic leukemia cells.

METHODS

Apoptosis was measured by the loss of mitochondrial membrane potential determined by flow cytometry using dihexyloxacarbocyanine iodide (DiOC6) and propidium iodide. Bcl-2 and Bax protein expression was also assessed by Western blot analysis.

RESULTS

P-OH and PTX induced loss of the mitochondrial membrane potential in U937 cells in vitro. Culturing the cells in the presence of both compounds caused a significant increase (p < 0.001) in apoptosis and expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins. However, despite their coexistence, Bax expression prevailed in our experiments. These data suggest that the effects of PTX might be attributable to changes in the mitochondrial membrane potential.

CONCLUSION

PTX sensitizes tumor cells to the anti-neoplastic action of P-OH. These observations may have clinical relevance in the treatment of cancer patients.

NF-kappaB and Hsp70 are involved in the phospholipase Cgamma1 signaling pathway in colorectal cancer cells

The majority of deaths from colorectal cancer are due to tumor invasion and metastasis. Induced migration of tumor cell is generally considered to be one critical step in cancer progression to the invasive and metastatic stage. Phospholipase Cgamma1 (PLCgamma1) is a key molecular switch in the process. But, the mechanism and function of PLCgamma1 in colorectal cancer motility are unclear. We showed first in this report that epidermal growth factor (EGF) stimulated the phosphorylation of PLCgamma1 in human colorectal cancer cell line LoVo. Inhibition of PLCgamma1 with the pharmacologic agent U73122 decreased the migration of LoVo cells in a dose-dependent manner while EGF treatment reversed it partially. PLCgamma1 signaling pathway also upregulated the activity of NF-kappaB. Furthermore, expression of Hsp70 was increased by treatment with U73122 or pyrrolidine dithiocarbamate (PDTC), a NF-kappaB inhibitor. These data indicated that PLCgamma1 played a pivotal role in the migration of human colorectal cancer cell and first demonstrated that upregulation of NF-kappaB binding activity and downregulation of Hsp70 expression were PLCgamma1-dependent in LoVo cells.

Roxithromycin inhibits constitutive activation of nuclear factor {kappa}B by diminishing oxidative stress in a rat model of hepatocellular carcinoma

PURPOSE

Recently, 14-member macrolide antibiotics such as clarithromycin and roxithromycin have been shown to have anticancer and antiangiogenic effects. We investigated the suppressive effect of roxithromycin on accelerated hepatocellular carcinoma growth in a rat hepatocarcinogenetic model and compared results with effects from TNP-470.

EXPERIMENTAL DESIGN

Tumor was induced by oral diethylnitrosamine administration for 17 weeks. Normal saline, TNP-470 (50 mg/kg), or roxithromycin (40 or 100 mg/kg) was administered i.p. thrice per week from week 10 to 17.

RESULTS

Carcinomatous tissue growing outside dysplastic nodules and a marked expression of placental glutathione S-transferase were detected in rats with induced carcinogenesis. Tumor growth was accompanied by augmented expression of inducible nitric oxide synthase, activation of nuclear factor kappaB, and increased lipid peroxidation level. All these effects were absent in animals that received roxithromycin or TNP-470. The inhibitory effect of roxithromycin was dose dependent and no clear differences were noted between groups given roxithromycin 100 mg/kg and TNP-470 50 mg/kg.

CONCLUSIONS

Our results indicate that roxithromycin inhibits oxidative stress, nitric oxide production, and nuclear factor kappaB activation induced by experimental hepatocarcinogenesis. The data provide additional evidence for the potential use of roxithromycin in treatment of hepatocellular carcinoma prevention.

Modification of an in vivo lung metastasis model of hepatocellular carcinoma by low dose N-nitrosomorpholine and diethylnitrosamine

Previously, we established the in vivo lung metastasis model of rat HCC induced by two hepatocarcinogens, diethylnitrosamine (DEN) and N-nitrosomorpholine (NMOR) at a dose of 120 ppm. This model allows us to investigate modifying factors leading to the inhibition of metastasis formation. However, low survival rates made the evaluation of metastasis formation difficult. The current experiments were conducted to modify the experimental protocol to improve survival and to establish a better animal metastasis model. Lower doses of NMOR (80 or 40 ppm in drinking water) were given to F344 rats for 14 weeks after DEN treatment. Survival rates in the 80 ppm group and in the 40 ppm group were 57% and 81%, respectively and these values were significantly higher than that in 120 ppm. Incidences of lung metastasis in the 40 ppm group steadily increased up to 67% by week 36 while that in the 80 ppm increased sharply up to 86% by week 24. Severity of lung metastases in the 40 ppm group at week 36 was mild compared with the 80 ppm group at week 24. In the second experiment, in order to characterize HCC development and lung metastasis in the 40 ppm group, rats given DEN and then followed with 40 ppm NMOR were killed sequentially. Development of HCC was observed at week 14 and reached 100% incidence at week 20. First lung metastatic lesions were evident at week 22, and incidence of lung metastasis reached 100%. Tumor cells were identified in the blood at week 20 by RT-PCR. The current study revealed that 40 ppm NMOR for 14 weeks after DEN treatment developed HCC without lung metastases at week 22, then HCC with a frequent lung metastasis at week 40. Thus, it can be said that this system is a more appropriate model for elucidation of mechanisms of metastasis and also for analysis of factors to inhibit natural metastasis.

Nuclear factor-kappaB and liver carcinogenesis

Hepatocellular carcinoma (HCC) is the third deadliest and fifth most common human cancer worldwide. Hepatitis C virus (HCV) and hepatitis B virus (HBV) infections along with alcohol and aflatoxin B1 intake are widely recognized etiological agents in HCCs. It is anticipated that HCCs will constitute a major health problem in the next two decades because of the rising incidence of HCV infections in the US. The poor survival rate achieved by current surgical procedures and chemotherapy treatment has prompted the scientific community to gain a better understanding of the molecular events involved in hepatocarcinogenesis in order to define new targets for more effective treatment. Recent findings from several laboratories have implicated constitutive activation of the transcription factor NF-kappaB as one of the early key events involved in neoplastic progression of the liver. Data is summarized here from recently published studies illustrating a crucial role of NF-kappaB in bridging the action of growth factors and inflammation to hepatic oncogenesis. Although additional work is needed to fully understand the precise role of NF-kappaB in the regulation of the various transitions of HCC development, these new findings raise the intriguing possibility that pharmacologic inhibition of NF-kappaB in the liver could selectively eradicate malignant liver cells without affecting normal liver homeostasis.

Tissue factor mediates inflammation

The role of tissue factor (TF) in inflammation is mediated by blood coagulation. TF initiates the extrinsic blood coagulation that proceeds as an extracellular signaling cascade by a series of active serine proteases: FVIIa, FXa, and thrombin (FIIa) for fibrin clot production in the presence of phospholipids and Ca2+. TF upregulation resulting from its enhanced exposure to clotting factor FVII/FVIIa often manifests not only hypercoagulable but also inflammatory state. Coagulant mediators (FVIIa, FXa, and FIIa) are proinflammatory, which are largely transmitted by protease-activated receptors (PAR) to elicit inflammation including the expression of tissue necrosis factor, interleukins, adhesion molecules (MCP-1, ICAM-1, VCAM-1, selectins, etc.), and growth factors (VEGF, PDGF, bFGF, etc.). In addition, fibrin, and its fragments are also able to promote inflammation. In the event of TF hypercoagulability accompanied by the elevations in clotting signals including fibrin overproduction, the inflammatory consequence could be enormous. Antagonism to coagulation-dependent inflammation includes (1) TF downregulation, (2) anti-coagulation, and (3) PAR blockade. TF downregulation and anti-coagulation prevent and limit the proceeding of coagulation cascade in the generation of proinflammatory coagulant signals, while PAR antagonists block the transmission of such signals. These approaches are of significance in interrupting the coagulation-inflammation cycle in contribution to not only anti-inflammation but also anti-thrombosis for cardioprotection.

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N-Acetylcysteine Augments Surface Thiols and Differentially Modulates Cell Adhesion and Invasion in vitro and Metastatic Potential in vivo of B16F1 Melanoma

The redox state of surface protein thiols influences a variety of cell functions, and we recently reported that adhesion molecules can be redox regulated. We investigated the effect of reducing surface thiols using N-acetylcysteine (NAC) on the biological properties of murine melanoma B16F1 cells. Treating the cells with NAC (5mM for 2h, then removed by washing) augmented their capacity to adhere to fibronectin, as well as to adhere to and invade an endothelial cell monolayer. This was associated with an augmented expression of reduced surface protein thiols. However, when control or NAC-pretreated melanoma cells were injected i.v. in mice to induce experimental lung metastases, we could observe an inhibition of metastatic potential by NAC. This discrepancy suggest that other redox sensitive steps, in addition to adhesion, are important in regulating the metastatic phenotype in vivo.