Enhanced invasion of Tax-expressing fibroblasts into the basement membrane is repressed by phosphorylated ascorbate with simultaneous decreases in intracellular oxidative stress and NF-kappa B activation

Effect of Diet and Supplementation on Serum Vitamin C Concentration and Antioxidant Activity in Dialysis Patients

Loss of vitamin C, especially in conjunction with an inadequate supply, can lead to decreased plasma concentrations of vitamin C. This in turn can lead to overt or subclinical deficiency. The present study aimed to evaluate the effects of diet and supplementation on vitamin C concentrations and serum antioxidant activity (FRAP) in hemodialysis (HD) patients. Sixty-eight HD patients participated in the study. In all of them, the diet was initially determined, and they were divided into five groups according to the diet and supplementation used. Group 1 received an unchanged diet, considered by them to be optimal; in group 2, the standard diet used in HD patients was introduced; in group 3, a standard diet enriched with natural antioxidants was employed; in group 4, a standard diet as in group 2 was used, but enriched with supplements (vitamin C, vitamin E, Se, and Zn). In contrast, group 5 consisted of HD patients with coexisting diabetes. Vitamin C serum levels were determined by high-performance liquid chromatography HPLC and antioxidant activity by The Ferric Reducing Ability of Plasma FRAP. The study shows that a well-chosen diet can slow the build-up of malnutrition and increase antioxidant activity as measured by the FRAP method in the blood of hemodialysis patients. Vitamin C supplementation can improve antioxidant status in hemodialysis patients. * The results presented in this paper complement our study, which assessed the effect of diet on the activity of erythrocyte antioxidant enzymes: Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), but also on the concentrations of non-enzymatic antioxidants (tocopherols, carotenoids, and vitamin C) in hemodialysis patients. In the study, plasma malondialdehyde (MDA) concentrations were assessed as an indicator of oxidative damage.

Inhibition of Liver Cancer Cell Proliferation and Migration by a Combination of (-)-Epigallocatechin-3- Gallate and Ascorbic Acid

A mixture of (-)-epigallocatechin-3-gallate (EGCG) and ascorbic acid exhibited 73.2% inhibition of SMMC-7721 cell proliferation in a soft agar colony formation assay, which was much higher than EGCG (40.4%) or ascorbic acid (12.4%) alone. In the cell migration assay, the mixture also significantly suppressed the migration of SMMC-7721 cells by 65.9% while EGCG and/or ascorbic acid did by 28.9% and 18.7%, respectively. Ascorbic acid was able to enhance the antioxidant activity of EGCG by decreasing the intracellular oxidative stress according to fluorographic analysis of oxidative stress. In conclusion, the combination of EGCG and ascorbic acid can strongly suppress the proliferation and metastasis of liver cancer cells, possibly with a mechanism associated with the scavenging of reactive oxygen species. All these events add to our knowledge of liver cancer chemotherapy.

Ds-echinoside A, a new triterpene glycoside derived from sea cucumber, exhibits antimetastatic activity via the inhibition of NF-κB-dependent MMP-9 and VEGF expressions

Ds-echinoside A (DSEA), a non-sulfated triterpene glycoside, was isolated from the sea cucumber Pearsonothuria graeffei. In vitro and in vivo investigations were conducted on the effects of DSEA on tumor cell adhesion, migration, invasion, and angiogenesis. In this study, we found that DSEA inhibited the proliferation of human hepatocellular liver carcinoma cells Hep G2, with a half-maximal inhibitory concentration (IC₅₀) of 2.65 μmol/L, and suppressed Hep G2 cell adhesion, migration, and invasion in a dose-dependent manner. DSEA also reduced tube formation of human endothelial cells ECV-304 on matrigel in vitro and attenuated neovascularization in the chick embryo chorioallantoic membrane (CAM) assay in vivo. Immunocytochemical analysis revealed that DSEA significantly decreased the expression of matrix metalloproteinase-9 (MMP-9), which plays an important role in the degradation of basement membrane in tumor metastasis and angiogenesis. DSEA also increased the protein expression level of tissue inhibitor of metalloproteinase-1 (TIMP-1), an important regulator of MMP-9 activation. From the results of Western blotting, the expressions of nuclear factor-kappa B (NF-κB) and vascular endothelial growth factor (VEGF) were found to be remarkably reduced by DSEA. These findings suggest that DSEA exhibits a significant anti-metastatic activity through the specific inhibition of NF-κB-dependent MMP-9 and VEGF expressions.

Differential effects of sulfated triterpene glycosides, holothurin A1, and 24-dehydroechinoside A, on antimetastasic activity via regulation of the MMP-9 signal pathway

Two sulfated triterpene glycosides, holothurin A(1) (HA(1)) and 24-dehydroechinoside A (DHEA), isolated from the sea cucumber Pearsonothuria graeffei, are of the holostane type with 18(20)-lactone and identical carbohydrate chains. DHEA has a side chain 23 (24)-double bond, while HA(1) has a hydroxyl group at C-21. In this study, we compared the effects of DHEA and HA(1) on metastasis in vitro and in vivo. The results show that HA(1) and DHEA treatment significantly suppressed adhesion of human hepatocellular liver carcinoma cells (HepG2) to both matrigel and human endothelial cells (ECV-304) and inhibited HepG2 cell migration and invasion in a dose-dependant manner. HA(1) and DHEA reduced tube formation of ECV-304 cells on the matrigel in vitro and attenuated neovascularization in the chick embryo using the chorioallantoic membrane (CAM) assay in vivo. Immunocytochemistry analyses revealed that both HA(1) and DHEA significantly decreased the expression of the matrix metallo-proteinase-9 (MMP-9) and increased the expression level of tissue inhibitor of metalloproteinase-1 (TIMP-1), an important regulator of MMP-9 activation. Western blot analyses demonstrated that HA(1) and DHEA remarkably abolished the expression of vascular endothelial growth factor (VEGF). The expression of nuclear factor-kappa B (NF-κB) was significantly decreased by HA(1), while DHEA treatment had no effect on the down regulation of NF-κB expression. These data suggest that both DHEA and HA(1) exert significant antimetastatic activities by inhibiting MMP-9 and VEGF expression. DHEA-induced antimetastasis was more potent than HA(1). In addition, only HA(1) treatment downregulated the expression level of NF-κB, suggesting that the antimetastatic activity of triterpene glycosides derived from P. graeffei can be either NF-κB-dependent or -independent, depending on their structure.

A flavonoid glycoside isolated from Smilax china L. rhizome in vitro anticancer effects on human cancer cell lines

The anticancer activity of eight crude extracts of Smilax china L. rhizome (SCR) against HeLa cells was assessed by MTT assay and clonogenic assay, the fraction rich in flavonoids had show good activity against HeLa cells. A bioassay-guided separation on this extract lead to the detection of kaempferol-7-O-beta-D-glucoside (KG), which belongs to flavonoid glycoside, displayed marked anticancer activity. We evaluated its in vitro cytotoxicity and antiproliferative effect in a panel of established cancer cell lines by MTT assay and clonogenic assay. KG induces A375 and HL60 cells apoptosis, which was demonstrated by morphological changes, DNA fragmentation and flow cytometric analysis. Fluorescent staining with Hoechst 33258 showed fragmentation and condensation of chromatin in the A375 and HL60 cells. Flow cytometric analysis shown that A375 and HL60 cells treated with KG resulted in the appearance of a hypodiploid peak (A0 region), probably due to the presence of apoptosing cells and/or apoptotic bodies with DNA content less than 2n. Quantitation of the hypodiploid cells shows a dose-dependent response to KG, and this result is in good accordance with that of the DNA fragmentation assay by agarose gel electrophoresis. Our results suggested that cell cycle arrest at G(1) phase and induce apoptosis as a mechanism by which KG exerts an antiproliferative effect.

Antimetastatic effect of a lipophilic ascorbic acid derivative with antioxidation through inhibition of tumor invasion

PURPOSE

Ascorbic acid (AA), the natural antioxidant, has been demonstrated to exert an antimetastatic action; however, AA is quite unstable in physiological condition. The aim of the present study is to investigate the stability, the antioxidation and the antimetastatic effects of three lipophilic AA derivatives in vitro as well as in vivo.

METHODS

The 95D cells were treated with ascorbic acid-2-O-phosphate-6-O-laureate (AA2P6L), ascorbic acid-2-O-phosphate-6-O-myristate (AA2P6M) and ascorbic acid-2-O-phosphate-6-O-stearate (AA2P6S). AA derivatives' stability in medium under cell culture condition, in the presence and in the absence of 95D cells, was assessed by high-performance liquid chromatography assay. Cell viability and intracellular oxidative stress were measured by MTT assay and CDCFH assay, respectively. Wound healing assay and cell adhesion assay were used to investigate the antimetastatic activities against 95D cells in vitro, and the C57BL/6 mice model was used to evaluate the antimetastatic action in vivo.

RESULTS

All the three AA derivatives exhibited excellent stability, significantly different from AA. Results of MTT assay showed that IC(50) values of the cytotoxicity of those AA derivatives, namely AA2P6L, AA2P6M and AA2P6S, were 38.46, 28 and 22.97 microg/ml, while the CDCFH assay indicated that EC(50) values of antioxidant effects on 95D cells were 31.12, 33.51 and 38.31 microg/ml, respectively. Through the ratio of IC(50) vs EC(50) for AA derivatives, AA2P6L was demonstrated to be the most effective AA derivative, which retained the antioxidant ability as well as low cytotoxicity. AA2P6L dose-dependently inhibited 95D cells' migration and adhesion, by 50% at the concentration of 20 and 57 microg/ml, respectively. In the animal experiment, intraperitoneal administration of 75 mg/kg AA2P6L decreased the number of metastatic nodules by 62% and elevated the survival rate of C57BL/6 mice about onefold compared to the control group.

CONCLUSION

AA2P6L, a lipophilic AA derivative with antioxidation, is shown to be a potent antimetastatic agent through the inhibition of tumor invasion. These results support future investigations on the feasibility of cancer chemotherapy with AA2P6L.

Repressions of MMP-9 expression and NF-kappa B localization are involved in inhibition of lung carcinoma 95-D cell invasion by (-)-epigallocatechin-3-gallate

Epigallocatechin-3-gallate (EGCG) repressed the invasion of lung carcinoma 95-D cells in invasion assay. RT-PCR analysis illuminated that 40 microM EGCG down-regulated the expression of MMP-9 by 45.7% and the result of Western blot analysis provided further evidence. NF-kappa B localized in the nucleus of the 95-D cells was diminished in a dose-dependent manner in EGCG-treated cells as shown by Western blot. Intracellular oxidants were more abundant in invasive cells than in invasion-suppressed cells fed with EGCG for 18 h. Thus, the inhibition of tumor invasion by EGCG was shown to be attributed to decreases of the expression of MMP-9 and NF-kappa B, which may result from decrease of intracellular oxidants.