Superoxide radical potentiates invasive capacity of rat ascites hepatoma cells in vitro

Hemorheology and oxidative stress in patients with differentiated thyroid cancer following I-131 ablation/metastasis treatment

BACKGROUND

Although radioiodine theraphy (RAIT) is thought to affect blood cells and oxidative stress, hemorheological alterations following dose-dependent RAIT remains unknown.

OBJECTIVE

The aim of this study was to determine the effects of RAIT on hemorheological and oxidative stress parameters in patients with differentiated thyroid cancers (DTC).

METHODS

Totally 31 DTC patients (mean age 46.32±11.15 years) and 26 healthy controls (mean age 50.50±6.22 years) were included. Venous blood samples were collected from each patient before and after treatment (7th day, 1th month and 6th month). Erythrocyte aggregation-deformability and oxidative stress parameters were determined. p < 0.05 was considered as statistically significant.

RESULTS

Erythrocyte deformability of the patients determined at 16.87 and 30 Pascal were significantly lower than healthy individuals. Erythrocyte aggregation index (AI) of the patients was higher, whereas erythrocyte aggregation half-time (t½) was lower compared to control. Erythrocyte deformability values and AI were not significantly different from the pre- and post-radioiodine treatment groups. There was no statistically significant difference between the oxidative stress parameters before and after the treatment.

CONCLUSIONS

Patients were in a worse hemorheological condition compared to healthy individuals. After RAIT, RBC deformability and aggregation were not affected and no significant change in oxidative stress parameters was detected.

Effects of green, oolong and black teas and related components on the proliferation and invasion of hepatoma cells in culture

The effects of teas and related components on the proliferation and invasion of cancer cells were examined by employing both in vitro proliferation and invasion assay systems. Powdered green, oolong and black tea extracts dose-dependently inhibited proliferation and invasion of a rat ascites hepatoma cell line of AH109A but did not affect the proliferation of the normal mesentery-derived mesothelial cells (M-cells) isolated from rats; higher concentrations of powdered oolong and black teas could restrain the proliferation of another tumor cell line of L929. The AH109A cells were found to penetrate underneath the monolayer of M-cells in the presence of 10% calf serum. When each rat serum obtained at 0.5, 1, 2, 3 and 5 h after oral intubation of each tea extract was added to the culture media instead of calf serum at a concentration of 10%, both the invasion and proliferation of AH109A were significantly suppressed. These ex vivo results suggest the potential bioavailability of effective tea components in rats. Furthermore, (-)-epigallocatechin gallate, (-)-epicatechin gallate and (-)-epigallocatechin from green tea as well as the mixture of theaflavin and theaflavin gallates from black tea were shown to be the most effective components against the invasion and proliferation of AH109A. These results show that the inhibitory effects of the teas and related components against AH109A cells are due to the cell-specific and higher sensitivity of the cell line to tea components.

Inhibitory effect of serum from rats administered with coffee on the proliferation and invasion of rat ascites hepatoma cells

The action of coffee on the proliferation and invasion of a rat ascites hepatoma cell line of AH109A was investigated using in vitro and ex vivo assay systems. When rats were given oral intubation of instant coffee powder solution, the sera of those rats had the potent inhibitory activity on both the proliferation and invasion of AH109A. The activity of rat serum was both time- and dose-dependent. The instant coffee powder also inhibited the proliferation and invasion of AH109A in vitro. These results indicate that coffee has anti-proliferative and anti-invasive activity both in vitro and ex vivo. They also suggest that some anti-proliferative and anti-invasive material(s), which may be the ingredient(s) of coffee or their metabolites, appear in rat serum when rats are given oral intubation of coffee, although a possibility that host defense systems may be activated by the oral intubation of coffee cannot be ruled out.

Assay systems for screening food components that have anti-proliferative and anti-invasive activity to rat ascites hepatoma cells: In vitro and ex vivo effects of green tea extract

We have developed in vitro and ex vivo assay systems for screening food components and natural substances that suppress the proliferation and/or invasion of a rat ascites hepatoma cell line of AH109A and have used them to study the effect of green tea extract. AH109A cells were found to penetrate underneath the monolayer of primary cultured mesothelial cells isolated from Donryu rat mesentery in the presence of 10% newborn bovine serum. Green tea extract inhibited this AH109A penetration in a dose dependent manner and also inhibited AH109A proliferation in vitro dose-dependently. Green tea tannin, the major polyphenolic substances in green tea extract, also inhibited the proliferation and invasion of AH109A in vitro in a dose dependent manner. When rat serum obtained 0.5 h after oral intubation of green tea extract was added to the culture media instead of newborn bovine serum at a concentration of 10%, the invasion of AH109A was significantly inhibited as compared to control rat serum (before green tea extract intubation); the inhibitory effect lasted for 1 h and disappeared 3 h after oral intubation of green tea extract, but those rat sera showed no inhibition of AH109A proliferation. These results suggest that green tea extract has an inhibitory effect on the invasion of AH109A both in vitro and ex vivo, but on the proliferation of AH109A only in vitro, and that these assay systems are effective for the screening of food components which inhibit tumor cell proliferation and invasion.

Tumor-associated macrophages (TAMs) form an interconnected cellular supportive network in anaplastic thyroid carcinoma

BACKGROUND

A relationship between the increased density of tumor-associated macrophages (TAMs) and decreased survival was recently reported in thyroid cancer patients. Among these tumors, anaplastic thyroid cancer (ATC) is one of the most aggressive solid tumors in humans. TAMs (type M2) have been recognized as promoting tumor growth. The purpose of our study was to analyze with immunohistochemistry the presence of TAMs in a series of 27 ATC.

METHODOLOGY/PRINCIPAL FINDINGS

Several macrophages markers such as NADPH oxidase complex NOX2-p22phox, CD163 and CD 68 were used. Immunostainings showed that TAMs represent more than 50% of nucleated cells in all ATCs. Moreover, these markers allowed the identification of elongated thin ramified cytoplasmic extensions, bestowing a "microglia-like" appearance on these cells which we termed "Ramified TAMs" (RTAMs). In contrast, cancer cells were totally negative. Cellular stroma was highly simplified since apart from cancer cells and blood vessels, RTAMs were the only other cellular component. RTAMs were evenly distributed and intermingled with cancer cells, and were in direct contact with other RTAMs via their ramifications. Moreover, RTAMs displayed strong immunostaining for connexin Cx43. Long chains of interconnected RTAMs arose from perivascular clusters and were dispersed within the tumor parenchyma. When expressed, the glucose transporter Glut1 was found in RTAMs and blood vessels, but rarely in cancer cells.

CONCLUSION

ATCs display a very dense network of interconnected RTAMs in direct contact with intermingled cancer cells. To our knowledge this is the first time that such a network is described in a malignant tumor. This network was found in all our studied cases and appeared specific to ATC, since it was not found in differentiated thyroid cancers specimens. Taken together, these results suggest that RTAMs network is directly related to the aggressiveness of the disease via metabolic and trophic functions which remain to be determined.

Inhibitory effect of curcumin on the invasion of rat ascites hepatoma cells in vitro and ex vivo

Curcumin, a yellow pigment in turmeric, is a food factor withantioxidative activity. The effect of curcumin on the proliferation and invasion of the rat ascites hepatoma AH109Acells was studied in vitro and ex vivo assay systems. Especially, a co-culture system of the hepatoma cellswith mesothelial cells derived from rat mesentery was employed to investigate the invasive motility. Curcumin suppressed thehepatoma slipping motility in a dose-dependent manner up to 5 muM and thereafter maintained the effect up to 20 muM, whereas this substance exerted little influence on the proliferation of the hepatoma cells at the same concentrations. Sera obtained from rats orally given curcumin also inhibited the AH109A cellular invasive movement when added to the culturemedium. Hepatoma cells previously cultured with hypoxanthineand xanthine oxidase showed a highly invasive activity. Curcumin and curcumin-loaded rat sera suppressed this reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with hypoxanthine, xanthine oxidase and either of curcumin samples. These resultssuggest that the antioxidative property of curcumin may beinvolved in its anti-invasive action.

Inhibitory effect of ascorbic Acid on the proliferation and invasion of hepatoma cells in culture

Effect of ascorbic acid (AsA) on the proliferation and invasion of rat ascites hepatoma AH109A cells was investigated by measuring [(3)H]thymidine incorporation into acid-insoluble fraction of the cells and by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells, respectively. AsA suppressed the invasion of AH109A cells in a dose-dependent manner at concentrations of 62.5-500 muM, while it inhibited the proliferation of the cells at higher concentrations of 250 and 500 muM. Hepatoma cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) or with hydrogen peroxide showed increased invasive activities. AsA suppressed the reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with AsA, HX and XO or with AsA and hydrogen peroxide. Furthermore, AsA reduced the intracellular peroxide levels in AH109A cells. These results suggest that the antioxidative property of AsA may be involved in its anti-invasive action on hepatoma cells.

Anti-invasive activity of α-tocopherol against hepatoma cells in culture via protein kinase C inhibition

Effects of α-, β-, γ- and δ-tocopherols on the proliferation and invasion of AH109A hepatoma cells and their modes of action were investigated. Four tocopherols inhibited the invasion as well as the proliferation of AH109A cells. Their inhibitory effects were more prominent on the invasion than on the proliferation. At 1 µM, α-tocopherol showed most potent anti-invasive activity without any influence on the proliferation. We have previously demonstrated that reactive oxygen species increase the invasion of AH109A cells. α-Tocopherol suppressed the reactive oxygen species-induced invasion but failed to suppress the reactive oxygen species-induced rises in intracellular peroxide level. GF 109203X, a protein kinase C inhibitor, decreased the invasive activity of AH109A cells. In contrast, phorbol-12-myristate-13-acetate, a protein kinase C activator, increased the invasive capacity of AH109A cells. α-Tocopherol suppressed the phorbol-12-myristate-13-acetate-induced increase in the invasion, and canceled the phorbol-12-myristate-13-acetate-induced rises in protein kinase C activity and phosphorylation of extracellular signal-regulated kinase. These results suggest that tocopherols, especially α-tocopherol, possess inhibitory effect more strongly on the invasion of AH109A cells than on the proliferation. They also suggest that the anti-invasive activity of α-tocopherol is raised through suppression of PKC/ERK signaling.

Oxidant/antioxidant balance in patients with thyroid cancer

PURPOSE

To compare the antioxidant enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the levels of lipid peroxidation product malondialdehyde (MDA) in blood samples of thyroid cancer patients compared to healthy controls.

METHODS

43 control subjects (mean age 44+/-13 years) and 43 patients (43+/-13 years) presented with multinodular goiter whose fine needle aspiration revealed malignant cytology were included into this study. The SOD, MDA and GSH-Px activities were measured in control subjects, and before/20 days after thyroidectomy in thyroid cancer patients.

RESULTS

SOD activities of pre-thyroidectomy, post-thyroidectomy and control groups were not different (p>0.05). Before thyroidectomy GSH-Px activities were lower (p<0.05) and MDA levels were higher (p<0.05) than the control group. In post- thyroidectomy, GSH-Px activity (p<0.05) increased, and MDA levels (p<0.05) decreased compared to prethyroidectomy levels. After thyroidectomy GSH-Px activity was significantly higher than the control group (p<0.05). Although post-thyroidectomy MDA levels significantly decreased, they were still higher than the control group (p<0.05).

CONCLUSION

The superoxide dismutase does not seem to change with thyroid cancer and thyroidectomy but both antioxidant glutathione peroxidase and lipid peroxidation product malondialdehyde do. These preliminary findings may point out oxidant/antioxidant imbalance associated with thyroid cancer.

Inhibitory effect of gingerol on the proliferation and invasion of hepatoma cells in culture

Effect of [6]-gingerol, a major pungent component in ginger, on the proliferation of a rat ascites hepatoma AH109A cells was investigated by measuring [(3)H]thymidine incorporation into acid-insoluble fraction of the cultured cells and that on the invasion by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells. [6]-Gingerol inhibited both the proliferation and invasion of hepatoma cells in a dose-dependent manner at concentrations of 6.25-200 muM (proliferation) and 50-200 muM (invasion). [6]-Gingerol accumulated cells in S phase and elongated doubling time of hepatoma cells, and increased the rate of apoptosis. Hepatoma cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) or with hydrogen peroxide showed increased invasive activities. [6]-Gingerol suppressed the reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with [6]-gingerol, HX and XO or with [6]-gingerol and hydrogen peroxide. Furthermore, [6]-gingerol reduced the intracellular peroxide levels in AH109A cells. These results suggest that the suppression of hepatoma cell proliferation by [6]-gingerol may be due to cell cycle arrest and apoptosis induction. They also suggest that the anti-oxidative property of [6]-gingerol may be involved in its anti-invasive activity of hepatoma cells.

Prevention of inflammation-mediated acquisition of metastatic properties of benign mouse fibrosarcoma cells by administration of an orally available superoxide dismutase

Weakly tumorigenic and nonmetastatic QR-32 cells derived from a fibrosarcoma in C57BL6 mouse are converted to malignant cells once they have grown after being coimplanted with a gelatine sponge which induces inflammation. We administered a newly developed peroral superoxide dismutase (SOD), oxykine, and as control vehicle, gliadin and saline, starting 2 days before the coimplantation and continued daily throughout the experiment. In the oxykine group, tumour incidence was lower (41%) than in the gliadin or saline group (83 and 79%, respectively). The inhibitory effect of oxykine was lost when an individual component of oxykine was administered, that is, SOD alone and gliadin alone. The effect was also abolished when administered by intraperitoneal route. When perfused in situ with nitroblue tetrazolium, an indicator of superoxide formation, the tumour masses from gliadin and saline groups displayed intense formazan deposition, whereas, those from oxykine group had less deposition. Enzymatic activity of SOD was also increased in oxykine group. Arising tumour cells in gliadin and saline groups acquired metastatic phenotype, but those in oxykine group showed reduced metastatic ability. These results suggested that the orally active SOD derivative prevented tumour progression promoted by inflammation, which is thought to be through scavenging inflammatory cell-derived superoxide anion.

Reactive oxygen species and induction of lignin peroxidase in Phanerochaete chrysosporium

We studied oxidative stress in lignin peroxidase (LIP)-producing cultures (cultures flushed with pure O(2)) of Phanerochaete chrysosporium by comparing levels of reactive oxygen species (ROS), cumulative oxidative damage, and antioxidant enzymes with those found in non-LIP-producing cultures (cultures grown with free exchange of atmospheric air [control cultures]). A significant increase in the intracellular peroxide concentration and the degree of oxidative damage to macromolecules, e.g., DNA, lipids, and proteins, was observed when the fungus was exposed to pure O(2) gas. The specific activities of manganese superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase and the consumption of glutathione were all higher in cultures exposed to pure O(2) (oxygenated cultures) than in cultures grown with atmospheric air. Significantly higher gene expression of the LIP-H2 isozyme occurred in the oxygenated cultures. A hydroxyl radical scavenger, dimethyl sulfoxide (50 mM), added to the culture every 12 h, completely abolished LIP expression at the mRNA and protein levels. This effect was confirmed by in situ generation of hydroxyl radicals via the Fenton reaction, which significantly enhanced LIP expression. The level of intracellular cyclic AMP (cAMP) was correlated with the starvation conditions regardless of the oxygenation regimen applied, and similar cAMP levels were obtained at high O(2) concentrations and in cultures grown with atmospheric air. These results suggest that even though cAMP is a prerequisite for LIP expression, high levels of ROS, preferentially hydroxyl radicals, are required to trigger LIP synthesis. Thus, the induction of LIP expression by O(2) is at least partially mediated by the intracellular ROS.

Inhibition of hepatoma cell invasion beneath mesothelial-cell monolayer by sera from tea- and related component-treated rats and their modes of action

The bioavailability and action of teas on the invasion of a rat ascites hepatoma cell line, AH109A, were determined and their modes of action were by co-culturing the cancer cells with a rat mesentery-derived mesothelial-cell (M-cell) monolayer in the presence of sera from rats orally given teas and their component, (-)-epigallocatechin gallate (EGCG). The rat sera obtained 2 and 5 hr after oral intubation of a low concentration of green, oolong, or black tea, or EGCG significantly inhibited AH109A invasion underneath the M-cell monolayer. These sera showed a time-dependent and significant inhibitory effect on the AH109A invasion. The 2-hr sera and 2.5 muM EDTA in the medium completely eliminated the enhancement of AH109A invasion induced by a reactive oxygen species (ROS)-generating system. These results show that the inhibition of relevant ROS-potentiated invasion of AH109A cells across the M-cell monolayer may be due to the antioxidative action of EGCG, the in vivo metabolites, and tea-induced changes in the endogenous substances. The results suggest that the drinking of tea in daily life may have certain preventive and therapeutic effects against cancer cell invasion.

Resveratrol suppresses hepatoma cell invasion independently of its anti-proliferative action

Resveratrol, found in grapes, is a phytoalexin with antioxidative activity. The compound (100 and 200 microM) inhibited the proliferation of hepatoma cells, although this phytoalexin exerted little influence up to 50 microM. Resveratrol, however, suppressed the invasion of the hepatoma cells even at a concentration of 25 microM. Sera from rats orally given resveratrol restrained only the invasion of AH109A cells. Resveratrol and resveratrol-loaded rat serum suppressed reactive oxygen species-potentiated invasive capacity. These results suggest that the anti-invasive activity of resveratrol is independent of the anti-proliferative activity, and that the antioxidative property of resveratrol may be involved in its anti-invasive action.

Oxygen free radicals mediate the induction of manganese superoxide dismutase gene expression by TNF-alpha

In this study, the hypothesis that oxygen free radicals act as intracellular messengers is examined. Treatment of human oral carcinoma SCC-25 cells with 200 ng/ml human TNF-alpha for 6 h greatly increased manganese superoxide dismutase (MnSOD) gene expression as detected by western blotting, RT-PCR, and nuclear run-on experiments. In the presence of the oxygen free radical spin trapping reagent, 5,5-dimethyl pyrroline-N-oxide (DMPO), the induction of MnSOD gene expression by TNF-alpha was significantly reduced. Electron paramagnetic resonance experiments showed that the production of oxygen free radicals was enhanced in TNF-alpha treated cells. Taken together, these observations suggest that the induction of MnSOD expression by TNF-alpha is at least partially mediated by intracellular formation of oxygen free radicals, and that superoxide is most likely the initiating species involved in the mediation of MnSOD gene expression by TNF-alpha.

Inhibitory effects of carotenoids on the invasion of rat ascites hepatoma cells in culture

The effects of carotenoids--alpha-carotene, beta-carotene, lycopene, beta-cryptoxanthin, zeaxanthin, lutein, canthaxanthin, astaxanthin--on the invasion of rat ascites hepatoma AH109A cells were investigated by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells (M-cells). All the carotenoids examined inhibited AH109A invasion in a dose-dependent manner up to 5 microM. Cancer cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) showed a highly invasive activity. Carotenoids, 5 microM of beta-carotene and astaxanthin, suppressed this reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with the carotenoids, HX and XO. These results suggest that the antioxidative property of these carotenoids may be involved in their anti-invasive action.

Peroxiredoxin I expression in human thyroid tumors

Peroxiredoxin I (Prx I) is newly discovered oxidative stress inducible protein, having a thioredoxin peroxidase activity. The Prx I expression level in 107 samples out of 60 thyroid lesions, including normal thyroid, tumors and thyroiditis including Graves' disease were examined using immunoblotting. Prx I expression levels in follicular neoplasm (P = 0.00005) and thyroiditis group (P = 0.0037) were significantly higher than that of the control group, while papillary carcinoma group did not show statistical significance. Immunohistochemistry indicated that Prx I was in epithelial cells of thyroid follicles. These results suggest that Prx I is expected to be a candidate for novel tumor markers to discriminate tissue types of tumors.

Effects of antioxidant enzyme overexpression on the invasive phenotype of hamster cheek pouch carcinoma cells

To examine the role of reactive oxygen species on the invasive phenotype of cancer cells, we overexpressed manganese- and copper-zinc-containing superoxide dismutases (MnSOD, CuZnSOD) and catalase (Cat) in hamster cheek pouch carcinoma (HCPC-1) cells in vitro using adenoviral vector-mediated gene transfer. Hamster cheek pouch carcinoma cells were transduced with these adenoviral vector constructs alone, or in combination, at concentrations [i.e., multiplicity of infectivity (MOI)] of 100 MOI each. The Escherichia coli beta-galactosidase reporter construct was used as a control virus. Protein expression was examined by Western blot analysis and enzymatic activities were measured using spectrophotometry. To observe the effects of transgene overexpression on in vitro tumor cell invasion, we used the membrane invasion culture system, an accurate and reliable method for examining tumor cell invasion, in vitro. This assay measures the ability of tumor cells to invade a basement membrane matrix consisting of type IV collagen, laminin, and gelatin. MnSOD overexpression resulted in a 50% increase in HCPC-1 cell invasiveness (p < .001); co-overexpression of MnSOD with Cat partially inhibited this effect (p < .05). Moreover, co-overexpression of both SODs resulted in a significant increase in invasiveness compared with the parental HCPC-1 cells (p < .05). These changes could not be correlated with the 72 kDa collagenase IV or stromolysin activities using zymography, or the downregulation of the adhesion molecules E-cadherin or the alpha4 subunit of the alpha4beta1 integrin. These results suggest that hydrogen peroxide may play a role in the process of tumor cell invasion, but that the process does not rely on changes in matrix metalloproteinase activity in the cells, or the expression of cell adhesion molecules.

Enhanced inhibition of experimental metastasis by the combination chemotherapy of Cu-Zn SOD and adriamycin

We previously reported that reactive oxygen species (ROS) enhance tumor cell metastasis, and by administration of recombinant human superoxide dismutase (rh SOD), an enzyme which scavenges O2- successfully reduced lung metastasis of mouse MethA sarcoma and Lewis lung carcinoma. These observations suggested that rh SOD suppressed tumor cell invasion by eliminating O2- the primary source of ROS. However, for the clinical application of the drug as an anti metastatic agent, rh SOD needs to be administered in combination with other cytotoxic agents, since SOD by itself has no cytotoxic activity. In this paper, we investigated the effectiveness of the combination chemotherapy of rh SOD and adriamycin (ADR), an anti-cancer agent against the experimental metastasis of highly metastatic clone, MH-02, which was derived from murine Meth A sarcoma. The present metastasis experiment clearly indicates that the administration of rh SOD enhances the antimetastatic effect of ADR. On the other hand, we found that the inhibition rate of metastasis exhibited by the combination chemotherapy of rh SOD and a certain dose (5 mg/ml) of ADR was inferior to that of rh SOD. This apparent paradoxical phenomenon was presumably explained by our finding that tumor cells themselves augment their invasive capacity and platelet aggregation, both of which are causative factors for metastasis formation, by generation of O2- when they were treated with ADR. Nevertheless, the combination chemotherapy of SOD with anticancer drugs such as ADR can be a practical anti-metastasis strategy.

Down-regulation of focal adhesion kinase, pp125FAK, in endothelial cell retraction during tumor cell invasion

Although endothelial cell retraction is required before tumor cell invasion, its molecular mechanism still remains obscure. We previously demonstrated that conditioned medium (CM) derived from a human pancreatic cancer cell line, PSN-1, induced endothelial cell retraction and facilitated tumor cell invasion. To investigate the molecular change of events in the transduction of extracellular signals during endothelial cell retraction, we examined the effect of the CM derived from PSN-1 cells on the tyrosine phosphorylation in endothelial cells. Immunoblot analyses revealed that the PSN-1 CM decreased tyrosine phosphorylation of a 120-130 kD protein, and induced the concomitant down-regulation of focal adhesion kinase, pp125FAK, during endothelial cell retraction in time- and dose-dependent fashions. These changes preceded endothelial cell retraction and were reversible after removal of the CM. Further quantitative densitometric analyses demonstrated that the extent of decrease in tyrosine phosphorylated 120-130 kD protein during the endothelial cell retraction was likely to be proportional to that of the down-regulation of pp125FAK. A tyrosine phosphorylated 120-130 kD protein immunoprecipitated by anti-phosphotyrosine antibody immunoreacted with anti-pp125FAK antibody. These results suggested that decreased amount of a tyrosine phosphorylated 120-130 kD protein probably due to the down-regulation of pp125FAK might be associated with the signal transduction pathway in the endothelial cells during their retraction. Furthermore, these findings were also observed in the CM from another four human cancer cell lines, suggesting the down-regulation of pp125FAK in endothelial cells during tumor cell invasion.

Enhancing effect of thoraco-laparotomy on liver metastasis and the role played by active oxygens in its mechanism

The enhancing effect on liver metastasis produced by the excessive surgical stress of thoraco-laparotomy (TL), and its regulation with a radical scavenger, were studied in 10-week-old Donryu rats. The rats were divided into three groups: those given thoraco-laparotomy for 1 h (the TL group); those given laparotomy alone for 1 h (the L group); those given a short laparotomy (the C group). The effects of treatment with 5 mg/kg of EPC-K1 was assessed in the TL group. A rat hepatocellular carcinoma cell line AH 60C (5 x 10(5) cells) was administered into the portal vein under general anesthesia. The number of metastatic liver nodules was counted 3 weeks later, and the lipid peroxide (LPO) levels of the liver and serum were measured by the TBA method on postoperative days (PODs) 1, 2, and 3. The number of metastatic liver nodules was 40.6 +/- 29.7, 15.0 +/- 15.8, and 13.7 +/- 9.4 in the TL, L, and C groups, respectively. When EPC-K1 was administered to the TL group, the LPO level on POD 1 decreased from 49.8 +/- 25.8 to 18.9 +/- 7.9 nM/g, and the number of metastatic liver nodules decreased from 27.2 +/- 30.0 to 8.9 +/- 12.7 in parallel. The findings of this study suggested that the excessive surgical stress produced by thoraco-laparotomy enhanced liver metastasis in parallel with an increase in LPO levels; however, the radical scavenger EPC-K1 could aid in reversing this effect.

Suppression of intracellular Cu-Zn SOD results in enhanced motility and metastasis of Meth A sarcoma cells

We have previously described an inverse relationship between Cu-Zn superoxide dismutase (SOD) activity and invasiveness of a clone of human tongue cancer cells. In these cells, suppression of Cu-Zn SOD activity by transfection with anti-sense cDNA enhanced motility in vitro. The present studies were undertaken to determine whether the inverse relationship between intracellular Cu-Zn SOD activity and motility is a general property of other tumor cells and whether this enzyme indeed defines in vivo metastatic potential. Murine Meth A sarcoma-derived ML-01 cells, which have low metastatic activity, were transfected with anti-sense Cu-Zn SOD cDNA. Two clones with very different SOD activities--ML-AS2, with the most suppressed, and ML-AS5, with the least suppressed activity-were analyzed for their motility and metastatic capability. Compared to the mocktransfectant ML-neo, the metastatic potential and motility of the ML-AS2 and ML-AS5 were increased 4.5- and 2.1-fold, respectively. Superoxide treatment enhanced the motility of the AS clones but not that of the ML-neo cells. Our results clearly show that there is an inverse relationship between the intracellular level of Cu-Zn SOD, cell motility and in vivo metastatic potential.

Basaloid-squamous cell carcinoma of the floor of the mouth: characterization of a cell line

Since it was first described in 1986, basaloid-squamous cell carcinoma (BSC) has been considered a distinct variant of squamous cell carcinoma that occurs in a variety of anatomic sites, including the head and neck region. We report the characterization of the first cell line established from a basaloid-squamous cell carcinoma of the floor of the mouth. The cell line exhibited a highly invasive capacity, indicating that BSC has very aggressive behavior. This cell line may be a useful model for elucidation of the biological characteristics of BSC.

Possible involvement of free radical scavenging properties in the action of tumor necrosis factor-alpha

Constitutive production of hydroxyl radicals from four established cancer cell lines was detected as spin adducts of 5,5-dimethyl-l-pyroline-N-oxide (DMPO), using an electron spin resonance spectrometer. The generated hydroxyl radicals was decreased in three out of four cancer cell lines when incubated in vitro for 3 h with TNF-alpha No direct scavenging effect of TNF-alpha on hydroxyl radicals or superoxide anions was observed in the in vitro radical generation system. The modulation of intracellular reactive oxygen species of these cancer cells by adding menadione or CuDIPS to the culture medium changed the antiproliferative effect of TNF-alpha on the cells. The ultrastructural localization of the radical-generating sites in cancer cells was visualized using the diaminobenzidine/horseradish peroxide histochemical system at the electron microscopic level. The hydrogen peroxide-dependent formation of electron-dense materials localized at the mitochondrial membranes was decreased after the treatment of the cancer cells with TNF-alpha. These data indicate that the reduction of radical generation in cancer cells by TNF-alpha may be an early mechanism that contributes to the antiproliferative effect of this cytokine on some cancer cells.

Imbalance in the antioxidant pool in melanoma cells and normal melanocytes from patients with melanoma

In order to evaluate the free radical defense systems of melanocytes and their possible correlation with melanoma, we have studied in cultured normal human melanocytes (20), normal melanocytes from melanoma patients (15), and melanoma cells (40) the fatty acid pattern of membrane phospholipids as a target of peroxidative damage and the superoxide dismutase and catalase activities, vitamin E, and ubiquinone levels as intracellular antioxidants. Cells were cultured in the same medium and analyzed at III or IV passage. Compared to the values obtained in normal human melanocytes, melanoma cells showed on average: a) higher levels of polyunsaturated fatty acids, b) increased superoxide dismutase and decreased catalase activities, higher vitamin E, and lower ubiquinone levels. Among the normal melanocytes from melanoma patients studied, two groups were differentiated: a) cultures (7) with enzymatic and non-enzymatic antioxidants level similar to those of normal human melanocytes; b) cultures (8) with antioxidant patterns similar to those observed in melanoma cells. Polyunsaturated fatty acids were also increased in the latter group. The results indicate that in melanoma cells and in a percentage of normal melanocytes from melanoma patients, an imbalance in the antioxidant system can be detected that can lead to endogenous generation of reactive oxygen species and to cellular incapability of coping with exogenous peroxidative attacks. These alterations could be correlated with the malignant transformation of cells and with the progression of the disease.

Enhanced paracellular barrier function of rat mesothelial cells partially protects against cancer cell penetration

To study pathophysiological roles of mesothelial barrier functions in protection against cancer cell invasion, we isolated mesothelial cells from the rat abdominal cavity and then cultured them with 10(-6)M all-trans-retinoic acid (RA) for 10 days. Mesothelial barrier function assessed by measuring transcellular electrical resistance (TER) and the expression of 7H6 tight junction-associated antigen at the cell border were induced by the treatment (10.01 +/- 0.8 vs 6.05 +/- 0.7 omega cm2, without RA; mean +/- s.e.m., n = 10). Then we quantified the attachment and penetration of rat mammary cancer cells (SST-2 cells) into the mesothelial cell monolayer by prelabelling of the cancer cells with fluorescent dye and by observing optical sections at different heights using a laser confocal scanning microscope. When SST-2 cells were overlaid onto the mesothelial cell monolayer treated with RA, the number of cancer cells found at the basal level of the monolayer was significantly reduced. These results showed that enhanced mesothelial barrier function at least partially prevents the penetration of cancer cells into mesothelial cells and suggested that 7H6 antigen serves as a reliable immunocytochemical marker for monitoring mesothelial barrier function.

Inhibition of in vitro tumor cell invasion by ginsenoside Rg3

The effect of plant glycosides on tumor cell invasion was examined. Among the glycosides tested, ginsenoside Rg3 was found to be a potent inhibitor of invasion by rat ascites hepatoma cells (MM1), B16FE7 melanoma cells, human small cell lung carcinoma (OC10), and human pancreatic adenocarcinoma (PSN-1) cells, when examined in a cell monolayer invasion model. Structurally analogous ginsenosides, Rb2, 20(R)-ginsenoside Rg2 and 20(S)-ginsenoside Rg3 (a stereoisomer of Rg3), showed little inhibitory activity. Neither Rh1, Rh2, 20(R)-ginsenosides Rh1, Rb1, Rc nor Re had any effect. The effective ginsenoside, Rg3, tended to inhibit experimental pulmonary metastasis by highly metastatic mouse melanoma B16FE7 cells as well. Taking account of our previous finding that 1-oleoyl-lysophosphatidic add (LPA) induced invasion by MM1 cells in the monolayer invasion model, the effect of Rg3 on molecular events associated with the invasion induced by LPA was analyzed in order to understand the mechanism of the inhibition. Rg3, which suppressed the invasion induced by LPA, dose-dependently inhibited the LPA-triggered rise of intracellular Ca2+. Protein tyrosine phosphorylation triggered by LPA was not inhibited by Rg3.

Establishment of high- and low-invasion clones derived for a human tongue squamous-cell carcinoma cell line SAS

Distant-organ metastasis and regional lymph node metastasis are still the major cause of mortality of oral-cavity squamous-cell cancer (SCC). However, only a few studies have been undertaken to elucidate the mechanism of invasion and metastasis of oral SCC. In this study, we attempted to establish human oral SCC clones with different invasiveness, defined by endothelial cell monolayer assay, which can be used for the study of invasion and metastasis of oral SCC. We established five clones from the human oral SCC cell line SAS by a limiting-dilution method. Two distinct clones, SAS-L1 with very low invasive potential and SAS-H1 with very high invasive potential, were picked out by rat lung endothelial cell monolayer assay. The number of SAS-H1 that penetrated the rat lung endothelial cell monolayer was six fold higher than the number of SAS-L1. There were no differences of metalloproteinase production and cell adhesiveness to Matrigel of SAS-L1 and SAS-H1. However, SAS-H1 exhibited a higher migration ability than SAS-L1. This pair of clones would be a useful experimental model to help in the study of the invasiveness of human oral SCC.

Effects of NG-nitro-L-arginine and/or L-arginine on experimental pulmonary metastasis in mice

Effects of NG-nitro-L-arginine methyl ester (L-NAME; an inhibitor of nitric oxide (NO) synthase) and/or L-arginine (substrate of NO synthase) on pulmonary metastasis of murine melanoma and Lewis lung carcinoma cells were investigated. L-NAME, L-arginine or both L-NAME and L-arginine was injected i.p. into mice 5, 3, and 1 h before and 1, 3, 5, and 7 h after the injection of tumor cells into mice via a tail vein. The administration of L-NAME (9.3 mumol/mouse) alone or L-arginine alone (46.5 or 186 mumol/mouse) potentiated pulmonary metastasis of highly and poorly metastatic B16 melanoma cells. L-NAME alone also increased the number of pulmonary metastasis of Lewis lung carcinoma cells, but L-arginine (185 mumol/mouse) did not. However, the combination of L-NAME and L-arginine increased the number of pulmonary metastasis of both the melanoma and Lewis lung carcinoma cells synergistically. L-NAME or L-arginine administration enhanced the retention of B16 melanoma cells in the lungs examined 24 h after the tumor cell injection. Synergistic effect of L-NAME and L-arginine was also seen in the tumor cell retention. The present results suggest that the metastatic potentials of the tumor cells do not simply correlate to NO production in vivo.

Lipoproteins in hypoxic tumor cells as traps of free radicals

We examined the role of main cell protective mechanisms in retaining the high resistance of ascitic cells (EAC, ZAH) to lipid peroxidation with respect to different stages of tumor-organism metabolic interactions. The following mechanisms were studied: (1) the activity of main EAC enzymatic antioxidants (GSH-Px, SOD); (2) changes in lipid metabolism, especially the content of the main PUFA (linoleic and arachidonic fatty acids) in EAC cells; (3) comparison of intracellular resistance between EAC/ZAH cytoplasmic sections (containing LP-granules or not) to lipid peroxidation (initialized directly by UV-light). We found that the high resistance to lipid peroxidation was typical for cytoplasma sections (without LP-granules) on all stages of tumor development in vivo. The intracellular LP-granules become the main sensitive targets for FR-action, but only in the chronic hypoxia state of EAC/ZAH tumor cells. The latter effect developed in close correlation with the following metabolic interactions: (1) increasing the proportion of PUFA (especially, arachidonic and linoleic acids) transported to EAC tumor cells from host organs and accumulated mainly in tumor LP-granules, and (2) decreasing the alpha-tocopherol content of these hypoxic EAC cells while no activation of the main cell antioxidative enzymes (GSH-Px, SOD) took place. The vitality and high resistance of EAC stationary cells were accompanied by the 'paradoxical' state with great differences between the resistance of the intracellular PUFA-rich granules and other cytoplasmic sections. A similar state was found in stationary ZAH cells. The cell state is in good agreement with the Dormandy's suggestion that PUFA-rich granules can trap reactive radical species preventing their interaction with 'critical' PUFA-membranes.

Suppressive effect of recombinant human Cu, Zn-superoxide dismutase on lung metastasis of murine tumor cells

The inhibitory effect of recombinant human Cu++Zn++superoxide dismutase (rhSOD) on metastasis of tumor cells in the mouse was investigated. In an experimental pulmonary metastasis model employing Meth A cells as inoculum, significant inhibition of metastasis was obtained by intravenous pre- and post-administration of rhSOD. An inhibitory effect of rhSOD was also observed in a spontaneous pulmonary metastasis model with 3LL cells as the inoculum. rhSOD was not observed to have any significant effects on the platelet-aggregating activity of tumor cells, the adhesiveness of tumor cells to vascular components (endothelial cells, laminin and type-IV collagen), or the growth of tumor cells either in vitro or in vivo. However, rhSOD suppressed invasion of Meth A and 3LL cells into Matrigel (an artificially reconstituted basement membrane of collagen, laminin and heparan sulfate) in the presence of hypoxanthine and xanthine oxidase, in vitro producers of superoxide. Thus, the present study shows that rhSOD is able to inhibit both experimental and spontaneous pulmonary metastasis, possibly through the suppression of tumor cell invasion into the extracellular matrix.

Effect of synthetic protease inhibitor on histologic changes and free radical activity in hamsters with pancreatic cancer

To investigate the effects of synthetic trypsin inhibitors on pancreatic cancer, camostat (FOY-305) was administered orally to hamsters with experimental pancreatic cancer induced by diisopropanol nitrosamine (DIPN). The effect of free radicals on carcinogenesis was examined by measuring the tissue levels of the scavengers superoxide dismutase (SOD) and glutathione peroxidase (GSX-Px), and pancreatic tissues were examined histologically. Cancers developed in all hamsters that survived 24 weeks in the DIPN group and the FOY group, but 80% of the cancers in the DIPN group were tubular adenocarcinomas, and 91% of those in the FOY group papillary adenocarcinomas. The SOD activity in the DIPN group was significantly lower in the cancerous area and the borderline region than in the non-cancerous region and normal tissue. SOD activity in the cancerous and borderline regions was higher in the FOY groups than in the DIPN group. GSH-Px levels in the borderline and non-cancerous regions were significantly higher in the FOY group than in the DIPN group. These results suggest that the synthetic protease inhibitor slows the progress of pancreatic cancer by its free radical scavenging activity.

Effect of (-)-epigallocatechin gallate, the main constituent of green tea, on lung metastasis with mouse B16 melanoma cell lines

(-)-Epigallocatechin gallate (EGCG), the main polyphenolic constituent of green tea, inhibits tumor promotion and chemical carcinogenesis in animal experimental systems. Here we report that the peroral administration of EGCG inhibited metastasis of B16 melanoma cell lines, such as B16-F10 and BL6, in both experimental and spontaneous systems.

Lowered superoxide dismutase in highly metastatic B16 melanoma cells

Superoxide dismutases (SOD), which are enzymes scavenging the superoxide radical, were studied in two variant lines of the B16 melanoma: B16F1 with low metastatic potential and B16F10 with high metastatic potential. SOD activity was measured by a method utilizing reduction in the chemiluminescence of luminol. Using cell free extracts it was shown that the highly metastatic B16F10 cell line has a SOD activity lower (20.70 +/- 3.07) units/mg protein, n = 8, than that of the less metastatic B16F1 cell line (81.38 +/- 6.78) units/mg protein, n = 8. Acrylamide gel electrophoresis suggested that Mn-SOD activity is higher in B16F1 cells.

Serum requirement for in vitro invasion by tumor cells

The effect of fetal calf serum (FCS) on in vitro invasion by rat ascites hepatoma cells (AH130) was studied by using the in vitro invasion assay. Although the coculture of the highly invasive clone (MM1) of AH130 cells and the mesothelial cell layer or endothelial cell layer in modified minimum essential medium supplemented with 10% FCS resulted in extensive penetration of the layer by the tumor cells, the omission of FCS resulted in an almost complete elimination of the in vitro invasion. The in vitro invasiveness by human small cell lung cancer cells (OC10) was also remarkably reduced by the omission of FCS from the assay medium, suggesting a requirement of serum for the in vitro tumor cell invasion. When 10% FCS was added to the medium 2 h after the tumor cell seeding in FCS-free invasion assay system, penetration by MM1 cells was observed within an hour. This rate of penetration was almost the same as that when 10% FCS was added at the time of tumor cell seeding. FCS was also required for the penetration of a mesothelial cell monolayer by MM1 cells in a defined growth medium (SFM-101), in which MM1 cells were well maintained. The invasion-inducing activity appears to be independent of the growth-stimulating activity in serum.

Recombinant human superoxide dismutases: production and potential therapeutical uses

In many pathological situations, tissue damage is caused by cellular generation of superoxide free radicals (O2-). These active species are generated during post-ischemic reperfusion of organs, in hyperoxic tissue, during acute and chronic inflammation and during exposure to ionizing radiation. Exogenous superoxide dismutase (SOD) was shown to significantly prevent such damage. The genes for human cytosolic Cu/ZnSOD and mitochondrial MnSOD were cloned and introduced into an E. coli expression system. The proteins were expressed in high yields and purified to homogeneity, yielding pharmaceutical-grade materials. These enzymes were used in a variety of in vivo animal models for the demonstration of their protective effects against oxidative damage. Comparative pharmacokinetic studies in rats have revealed that the half-life of Cu/ZnSOD was 6-10 min., while that of MnSOD was 5-6 hours, thus indicating that MnSOD may be superior to Cu/ZnSOD for the treatment of chronic diseases. Indeed, MnSOD was found to be effective as an anti-inflammatory agent in the rat carrageenan induced paw edema acute inflammation model. Both enzymes were also effective in ameliorating post-irradiation damage in mice exposed to whole-body or localized chest X-ray radiation.

Purification and characterization of tumor invasion-inhibiting factors

Tumor invasion-inhibiting factors were purified from bovine liver using an in vitro system for estimating the tumor invasion ability. The acid-ethanol extract of liver was subjected to ultrafiltration (Amicon PM10 membrane), and the fraction corresponding to the molecular weight range below 10,000 was further fractionated by ion-exchange (DEAE-Toyopearl), gel filtration (Bio-Gel P6), and reverse-phase (C18) chromatographies. Two types of active polypeptides with molecular weights of about 5,000 and 2,000 were purified and named IIF-1 and IIF-2, respectively. Both peptides inhibited tumor invasion with half-maximum concentrations of 2-6 ng/ml in vitro. The amino acid compositions of both peptides were determined.

In vitro invasion of endothelial cell monolayer by rat ascites hepatoma cells

To study the tissue preference of invasion, we developed an assay system for the invasion of endothelial cells as a modification of the previously established assay of tumor cell invasion of mesothelial cells. Rat ascites hepatoma cells (AH 130) that had been seeded on a monolayer of cultured endothelial cells penetrated and formed tumor cell colonies under the monolayer. The penetration was time-dependent and the number of penetrated tumor cells and colonies was proportional to the number of tumor cells seeded. Comparison of the in vitro tumor cell invasion of endothelial cell monolayer with that of cultured mesothelial cell layer showed that a clone from the tumor cells (Cl-30) which was highly penetrative into the mesothelial cell layer had only limited ability to penetrate the endothelial cell layer.

Inhibition of in vitro tumor cell invasion by transmethylation inhibitors

Three inhibitors of S-adenosylmethionine-mediated transmethylation, 5'-methylthioadenosine (MTA), 2'-deoxyadenosine and sinefungin, inhibited in vitro invasion by a highly invasive clone (Cl-30) of rat ascites hepatoma cells, AH 130 (AH cells). Difluoromethylthioadenosine (DFMTA), a non-metabolizable derivative of MTA, also caused strong inhibition of invasion at concentrations that did not suppress the growth of the tumor cells. Cl-30 cells precultured in methionine-depleted medium showed decreased invasiveness. DFMTA was also effective on the invasion by fibrosarcoma, B16 melanoma and human lung carcinoma cell lines.

Benzoyl peroxide enhances the invasive ability of a mouse epidermal carcinoma cell line

The effect of the skin tumor promoter benzoyl peroxide on the invasive potential of a murine squamous carcinoma cell line was investigated using an in vitro assay based on the capacity of cells to migrate through a porous filter coated with matrigel. Pre-treatment of the murine squamous carcinoma cell line CH72 with benzoyl peroxide added to the tissue culture medium increased the invasive capacity of these cells 5-8 times. No effects were observed on cells from primary cultures of normal murine epidermis. The simultaneous treatment of CH72 cells with benzoyl peroxide and the free radical scavengers, superoxide dismutase or CuSO4, prevented the increase and the values did not differ significantly from the baseline invasive potential. This suggests that activated oxygen species participate in the benzoyl peroxide-induced enhancement of the invasive capacity of these carcinoma cells.

Potentiation of invasive capacity of rat ascites hepatoma cells by transforming growth factor-beta

The in vitro invasive capacity of poorly invasive cells (W1), which were cloned from rat ascites hepatoma cells (AH 130), was potentiated dose- and time-dependently by pretreating the cells with transforming growth factor-beta (TGF-beta). This potentiation of invasive capacity was completely abolished by anti-TGF-beta antibody. When the treated cells were ip inoculated into rats, the cells extensively invaded the peritoneum, and formed penetrating tumor nodules. The effect of TGF-beta was reversed by subculturing the treated cells without TGF-beta. The potentiation of invasive capacity by TGF-beta might participate in platelet-associated enhancement of tumor cell metastasis.