Inhibitory effects of RRR-α-tocopheryl succinate on benzo(a)pyrene (B(a)P)-induced forestomach carcinogenesis in female mice

Vitamin E succinate exerts anti-tumour effects on human cervical cancer cells via the CD47-SIRPɑ pathway both in vivo and in vitro

Vitamin E succinate (RRR-a-tocopheryl succinate, VES) acts as a potent agent for cancer therapy and has no toxic and side effects on normal tissue cells. However, the mechanism by which VES mediates the effects are not yet fully understood. Here, we hypothesised that VES mediates antitumour activity on human cervical cancer cells via the CD47-SIRPɑ pathway in vivo and in vitro. Results indicated that the human cervical cancer HeLa cells treated with VES were more efficiently engulfed by THP-1-derived macrophages. In response to VES, the protein expression of CD47 on cell membranes and the mRNA level of CD47 in different human cervical cancer cells significantly decreased. And the level of calreticulin (CRT) mRNA in the VES-treated cells increased. By contrast, CRT protein expression was not altered. miRNA-155, miRNA-133 and miRNA-326 were up-regulated in the VES-treated HeLa cells. Knocking down miRNA-155 and miRNA-133 by RNA interference increased CD47 protein expression in the VES-treated cells. In vivo efficacy was determined in BALB/C nude mice with HeLa xenografts. Results showed that VES reduced tumour growth, increased overall survival and inhibited CD47 in the tumour transcriptionally and translationally. Furthermore, inflammatory factors (TNF-α, IL-12, IFN-γ, IL-2 and IL-10) in the spleen were altered because of VES treatment. Our results suggest that VES-induced antitumour activity is coupled to the CD47-SIRPɑ pathway in human cervical HeLa cancer cells.

Safety Assessment of Tocopherols and Tocotrienols as Used in Cosmetics

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 14 tocopherols and tocotrienols and concluded these ingredients are safe as used in cosmetics. The tocopherols are reported to function in cosmetics as antioxidants or skin-conditioning agents; in contrast, tocotrienols are not reported to function as an antioxidants in cosmetics but as a light stabilizer, oral care agent, or skin-conditioning agent. The Panel reviewed the new and existing animal and clinical data to determine the safety of these ingredients and found it appropriate to extrapolate the existing information to conclude on the safety of all the tocopherols and tocotrienols.

Akt/AMPK/mTOR pathway was involved in the autophagy induced by vitamin E succinate in human gastric cancer SGC-7901 cells

Vitamin E succinate (VES), a derivative of vitamin E, is a promising cancer chemopreventive agent that inhibits tumor promotion by inducing apoptotic cell death. The effects of VES on autophagy, an intricate programmed process which helps cells survive in some stressed situations by degrading some cytoplasmic material, are unclear. When human gastric cancer cells SCG-7901 were exposed to VES, both the level of microtubule-associated protein 1 light chain 3 and the yeast ATG6 homolog Beclin-1 increased, and related autophagy genes were activated, thereby suggesting that autophagy was induced by VES. We also observed that VES-induced autophagy was accompanied by the activation of AMP-activated protein kinases (AMPK). VES-induced autophagy decreased when AMPK was inhibited by using small interfering RNA (siRNA), thereby suggesting that VES-induced autophagy is mediated by AMPK. Moreover, further studies revealed that the decreased activity of mammalian target of rapamycin (mTOR) and its downstream targets P70S6K and 4EBP-1 were involved in VES-activated autophagy associated with AMPK activation. The experiments also showed that the activity of protein kinases B (Akt)-mTOR axis was inhibited by VES. VES-induced AMPK activation could be attenuated by Akt activation. Overall, our studies demonstrated that AMPK was involved in the VES-induced autophagy. Crosstalk exists between AMPK and the Akt/mTOR axis. The results elucidated the mechanism of VES-induced autophagy in human gastric cancer cells.

Effect of vitamin E succinate on the expression of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor in gastric cancer cells and CD4(+) T cells

Gastric malignancy, which shows poor prognosis, is one of the most frequent causes of cancer-associated deaths. Vitamin E succinate (VES) inhibits cell proliferation and induces apoptosis in a concentration- and time-dependent manner. We explored the effect of VES on the expression of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor in gastric cancer cells and CD4(+) T cells. On one hand, VES dose-dependently regulated the expression of the TRAIL receptor in gastric cancer cells. Moreover, the activation of the TRAIL receptor, death receptor 4 (DR4), and death receptor 5 (DR5) in gastric cancer cells increased for up to 12 h. On the other hand, the expression of TRAIL protein in human CD4(+) T cells was obviously upregulated in the presence of VES. On the basis of these findings, we combined VES and human CD4(+) T cells to induce apoptosis of MKN28 human gastric cancer cells. The results showed that VES induced higher gastric cancer cell apoptosis when combined with human CD4(+) T cells than when applied alone. We conclude that VES can induce the expression of TRAIL receptor in gastric cancer cells, as well as the expression of TRAIL in CD4(+) T cells. Overall, our results provide a theoretical basis for future immunotherapy studies.

The Combination of α-Tocopheryl Succinate and Sodium Selenite on Breast Cancer: A Merit or a Demerit?

α-Tocopheryl succinate (α-TOS), a mitochondria-targeting agent, induces apoptosis in malignant cells in vitro and in vivo. Selenite is a nutritional supplement that has been shown to stimulate apoptosis in cancer cells. This study was designed to investigate the cytotoxic effect of combined treatment of α-TOS and sodium selenite (SSe) in vitro and in vivo and to explore their effect on apoptosis and autophagy in breast cancer. The type of interaction between α-TOS and SSe was evaluated and levels of oxidative stress and apoptotic and autophagic markers were determined. SSe alone showed varying degrees of cytotoxicity on all the tested cell lines. Its combination with α-TOS was antagonistic in vitro in MCF7 and in vivo in mice bearing Ehrlich tumor compared to α-TOS-treated one. Combination of TOS with 2 μM of SSe increased the level of glutathione without changes in antiapoptotic markers Bcl-2 and Mcl-1 at 16 and 48 hrs. SSe decreased caspase 3 activity and protein level of caspases 7 and 9, while it increased autophagic markers beclin-1 and LC3B protein levels of MCF7 cells treated with α-TOS. In conclusion, SSe antagonizes α-TOS-induced apoptosis via inhibition of oxidative stress and promoting prosurvival machinery of autophagy.

Evaluation of estrogen receptor expression and its relationship with clinicopathologic findings in gastric cancer

Background:

The presence of estrogen receptor alpha has been reported in the cell and tissue levels in gastric cancer; however, its impact on patients’ survival remains unclear. The aim of this study was to investigate the expression of estrogen receptor in gastric carcinoma as well as its relationship with the clinicopathologic findings of the patients.

Materials and Methods:

The study was performed on 100 endoscopic biopsies of gastric adenocarcinoma for estrogen receptor expression using an immunohistochemical method, and their relationship with the clinicopathologic findings of the patients, such as age, gender, tumor site, size, grade, depth of tumor invasion (T), and lymphatic status (N), were analyzed using independent sample t-test and Pearson Chi-square test. A P < 0.05 was considered significant in all analyses.

Results:

Using an immunohistochemical method on endoscopic biopsies of 74 males and 26 females with the mean age of 63 years, estrogen receptor was found to be positive in 41% of patients. No significant difference was found between estrogen receptor expression and other clinicopathologic findings (P = 0.75). There was a significant difference between estrogen receptor (+) and estrogen receptor (−) groups in nodal involvement (P = 0.001). The estrogen receptor (+) patients had more number of lymph nodes involved.

Conclusion:

This study showed that lymph node involvement has a significant relationship with estrogen receptor expression. However, no significant relationship was found between estrogen receptor expression and other clinicopathologic findings such as age, gender, tumor site in stomach, tumor size, tumor grade, and T-stage.

Inhibitory action of benzo[α]pyrene on hepatic lipoprotein receptors in vitro and on liver lipid homeostasis in mice

BACKGROUND

Dyslipidemia associated with obesity often manifests as increased plasma LDL and triglyceride-rich lipoprotein levels suggesting changes in hepatic lipoprotein receptor status. Persistent organic pollutants have been recently postulated to contribute to the obesity etiology by increasing adipogenesis, but little information is available on their potential effect on hepatic lipoprotein metabolism.

OBJECTIVE

The objective of this study was to investigate the effect of the common environmental pollutant, benzo[α]pyrene (B[α]P) on two lipoprotein receptors, the LDL-receptor and the lipolysis-stimulated lipoprotein receptor (LSR) as well as the ATP-binding cassette transporter A1 (ABCA1) using cell and animal models.

RESULTS

LSR, LDL-receptor as well as ABCA1 protein levels were significantly decreased by 26-48% in Hepa1-6 cells incubated (<2 h) in the presence of B[α]P (≤1 µM). Real-time PCR analysis and lactacystin studies revealed that this effect was due primarily to increased proteasome, and not lysosomal-mediated degradation rather than decreased transcription. Furthermore, ligand blots revealed that lipoproteins exposed to 1 or 5 µM B[α]P displayed markedly decreased (42-86%) binding to LSR or LDL-receptor. B[α]P-treated (0.5 mg/kg/48 h, i.p. 15 days) C57BL/6J mice displayed higher weight gain, associated with significant increases in plasma cholesterol, triglycerides, and liver cholesterol content, and decreased hepatic LDL-receptor and ABCA1 levels. Furthermore, correlational analysis revealed that B[α]P abolished the positive association observed in control mice between the LSR and LDL-receptor. Interestingly, levels of other proteins involved in liver cholesterol metabolism, ATP-binding cassette transporter G1 and scavenger receptor-BI, were decreased, while those of acyl-CoA:cholesterol acyltransferase 1 and 2 were increased in B[α]P-treated mice.

CONCLUSIONS

B[α]P demonstrates inhibitory action on LSR and LDL-R, as well as ABCA1, which we propose leads to modified lipid status in B[α]P-treated mice, thus providing new insight into mechanisms underlying the involvement of pollutants in the disruption of lipid homeostasis, potentially contributing to dyslipidemia associated with obesity.

RRR-α-tocopheryl succinate induces apoptosis in human gastric cancer cells via the NF-κB signaling pathway

To investigate the effects of the nuclear factor (NF)-κB signaling pathway on the induction of apoptosis by vitamin E succinate (RRR-α-tocopheryl succinate; VES) in human gastric carcinoma cells. Human gastric carcinoma SGC-7901 cells were treated with temperate concentrations of VES and pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. Cell viability and apoptosis were respectively estimated by methylthiazol tetrazolium (MTT) assay and the Annexin V‑FITC method. Western blot analysis was used to evaluate the protein expressions of NF-κBp65 and Bcl-2 family members Bcl-2, Bax and cleavage of caspase-3, caspase-9, and poly (ADP-ribose) polymerase (PARP). The DNA-binding activity of NF-κBp65 was measured by electrophoretic mobility shift assay (EMSA). Reverse transcription and polymerase chain reaction (RT-PCR) was implemented to evaluate the transcription of inhibitor of apoptosis (IAP) genes. Apoptosis assessment showed that VES induces apoptotic cell death in human gastric carcinoma cells. In the following experiments, PDTC (100 µM) was used in cell treatment 2 h before VES. The decreased ratio of the nuclear and cytosolic NF-κBp65 protein level was induced by VES and PDTC reinforced this trend. PDTC treatment significantly enhanced the decrease of NF-κB-DNA binding activity induced by VES in human gastric SGC-7901. The decrease in protein expression of Bcl-2 as well as the increase in the protein expression of Bax were induced by VES treatment. The cleavage of caspase-9, caspase-3 and PARP was induced. There was no effect on the gene transcription of c-IAP-1, c-IAP-2, and x-linked IAP (XIAP) compared with the control group, whereas mRNA levels of survivin and the neuronal apoptosis inhibitory protein (NAIP) markedly decreased. Notably, pretreatment with PDTC reinforced all the above VES-induced effects. In conclusion, VES-induced apoptosis in SGC-7901 cells is accompanied by the inhibition of the NF-κB signaling pathway, including changes in Bcl-2 family members, cleavage of caspases and gene transcription of survivin and NAIP.

Vitamin E-based nanomedicines for anti-cancer drug delivery

This review aims to highlight the development of novel vitamin E conjugates for the vectorization of active pharmaceutical ingredients through nanotechnologies. The physico-chemical and biological properties of vitamin E derivatives offer multiple advantages in drug delivery like biocompatibility, improvement of drug solubility and anticancer activity. Nanomedicines have shown high potential in drug delivery since (i) they may offer better drug biopharmaceutical properties such as longer half-life or better bioavailability and (ii) they have shown benefits in cancer therapy by improving anticancer drug therapeutic index. Vitamin E-based nanomedicines were developed to combine the pharmaceutical properties of both vitamin E and nanomedicines for two purposes: (i) to improve water solubility of hydrophobic drugs and (ii) to enhance the therapeutic efficiency of anticancer agents. This review is divided into three parts: the first one describes the biology and the metabolic functions of vitamin E, the second one focuses on the anticancer activity of two vitamin E derivatives: vitamin E succinate (TOS) and vitamin E polyethylene glycol-succinate (TPGS). Finally, in the third part, we discuss vitamin E derivatives based-nanomedicines.

Antifibrotic effects of tocotrienols on human Tenon's fibroblasts

PURPOSE

To compare the antifibrotic effect of vitamin E isoforms alpha-, gamma-, and delta-tocotrienol on human Tenon's fibroblasts (hTf) to the antimetabolite mitomycin C.

METHODS

Antifibrotic effects of alpha- (40, 60, 80, 100, and 120 microM), gamma- (10, 20, 30, and 40 microM) and delta-tocotrienol (10, 20, 30, and 40 microM) on hTf cultures were evaluated by performing proliferation, migration and collagen synthesis assays. Whereas for vitamin E the exposure time was set to 7 days to mimic subconjunctival application, cultures were exposed only 5 min to mitomycin C 100 microg/ml to mimic intraoperative administration. Cell morphology (phase contrast microscopy) as an assessment for cytotoxicity and cell density by measuring DNA content in a fluorometric assay to determine proliferation inhibition was performed on day 0, 4, and 7. Migration ability and collagen synthesis of fibroblasts were measured.

RESULTS

All tested tocotrienol isoforms were able to significantly inhibit hTf proliferation in a dose-dependent manner (maximal inhibitory effect without relevant morphological changes at day 4 for alpha-tocotrienol 80 microM with 36.7% and at day 7 for alpha-tocotrienol 80 microM with 42.6% compared to control). Degenerative cell changes were observed in cultures with concentrations above 80 microM for alpha- and above 30 microM for gamma- and delta-tocotrienol. The highest collagen synthesis inhibition has been found with 80 microM alpha-tocotrienol (62.4%) and no significant inhibition for mitomycin C (2.5%). Migration ability was significantly reduced in cultures exposed to 80 microM alpha- and 30 microM gamma-tocotrienol (inhibition of 82.2% and 79.5%, respectively, compared to control) and also after mitomycin C treatment (60.0%). Complete growth inhibition without significant degenerative cell changes could only be achieved with mitomycin C.

CONCLUSION

In vitro, all tested tocotrienol isoforms were able to inhibit proliferation, migration and collagen synthesis of human Tenon's fibroblasts and therefore may have the potential as an anti-scarring agent in filtrating glaucoma surgery.

Bid integrates intrinsic and extrinsic signaling in apoptosis induced by alpha-tocopheryl succinate in human gastric carcinoma cells

The underlying mechanisms of alpha-tocopheryl succinate (alpha-TOS)-mediated apoptosis are not understood in detail, although the redox-silent vitamin E analog is a potent apoptogen and anti-cancer agent. Our previous studies showed the important role of Fas signaling in apoptosis induced by the mitocan. The objective of the present study was to investigate whether apoptosis triggered by alpha-TOS in gastric carcinomas cells involves both mitochondria- and death receptor-dependent pathways. alpha-TOS induced apoptosis and mitochondrial permeability transition in a concentration- and time-dependent manner. As a consequence, cytochrome c and the apoptosis-inducing factor were released and caspases were activated. Bax was translocated from the cytosol to mitochondria and Bid was cleaved into its truncated form, tBid. Knocking down Bid by RNAi and Fas antisense oligodeoxynucleotides resulted in a decreased release and cleavage. The results imply that Bid may serve as a critical integrating factor of the death receptor and mitochondrial pathway in alpha-TOS-mediated apoptosis.

Vitamin E analogues as mitochondria-targeting compounds: from the bench to the bedside?

Despite considerable effort focusing on designing and finding efficient anti-cancer drugs over the last decade, little progress has been achieved, in particular in case of highly recalcitrant malignancies. Also, since there is a trend suggesting that deaths from cancers may be more frequent than from cardiovascular diseases, it is important to look for novel efficient and selective therapeutic approaches to gradually start winning the battle with cancer. Redox-silent vitamin E analogues, epitomised by alpha-tocopheryl succinate, give some hope in the quest for drugs with such properties. Thus far, these agents have been successfully tested in experimental animals with different types of cancer, showing high efficacy against malignancies including HER2-positive breast carcinomas or malignant mesotheliomas. Further research will provide additional, necessary data to launch clinical trials, possibly in near future, translating into development of innovative anti-cancer drugs acting by targeting mitochondria selectively in cancer cells.

Vitamin E succinate induces NAG-1 expression in a p38 kinase-dependent mechanism

NAG-1 (nonsteroidal anti-inflammatory drug-activated gene), a member of the transforming growth factor-beta superfamily, is involved in many cellular processes, such as inflammation, apoptosis/survival, and tumorigenesis. Vitamin E succinate (VES) is the succinate derivative of alpha-tocopherol and has antitumorigenic activity in a variety of cell culture and animal models. In the current study, the regulation and role of NAG-1 expression in PC-3 human prostate carcinoma cells by VES was examined. VES treatment induced growth arrest and apoptosis as well as an increase in NAG-1 protein and mRNA levels in a time- and concentration-dependent manner. VES treatment induced nuclear translocation and activation of p38 kinase. Pretreatment with p38 kinase inhibitor blocked the VES-induced increase in NAG-1 protein and mRNA levels, whereas an inhibition of protein kinase C, Akt, c-Jun NH(2)-terminal kinase, or MEK activity had no effect on VES-induced NAG-1 levels. Forced expression of constitutively active MKK6, an upstream kinase for p38, induced an increase in NAG-1 promoter activity, whereas p38 kinase inhibitor blocked MKK6-induced increase in NAG-1 promoter activity. VES treatment resulted in >3-fold increase in the half-life of NAG-1 mRNA in a p38 kinase-dependent manner and transient transfection experiment showed that VES stabilizes NAG-1 mRNA through AU-rich elements in 3'-untranslated region of NAG-1 mRNA. The inhibition of NAG-1 expression by small interfering RNA significantly blocked VES-induced poly(ADP-ribose) polymerase cleavage, suggesting that NAG-1 may play an important role in VES-induced apoptosis. These results indicate that VES-induced expression of NAG-1 mRNA/protein is regulated by transcriptional/post-transcriptional mechanism in a p38 kinase-dependent manner and NAG-1 can be chemopreventive/therapeutic target in prostate cancer.

α-Tocopheryl succinate-induced apoptosis in human gastric cancer cells is modulated by ERK1/2 and c-Jun N-terminal kinase in a biphasic manner

Gastric neoplastic disease is one of the most frequent causes of cancer-associated deaths with poor prognosis. Here we studied the effect of the redox-silent analogue alpha-tocopheryl succinate (alpha-TOS), a strong apoptogen and anti-cancer agent, on the gastric cancer cell line SGC-7901. alpha-TOS inhibited proliferation of the cells and induced their apoptosis in a concentration- and time-dependent manner, while succinate or alpha-tocopherol showed no effect. The effect of alpha-TOS was modulated by components of the MAPK signaling network, including ERK1/2 and c-Jun N-terminal kinase (JNK), but not p38. Activation of ERK1/2 occurred early and increased until 12h, coinciding with an in crease in apoptosis in the cells, after which it dropped abruptly, while activation of JNK rose steadily, reaching a plateau at 12h of alpha-TOS treatment. The effects of ERK1/2 and JNK on the apoptosis outcome are transmitted via c-Jun, since transfection of the cells with c-Jun antisense oligodeoxynucleotide inhibited alpha-TOS-induced apoptosis. We conclude that ERK1/2 and JNK positively regulate apoptosis induced in gastric cancer cells by alpha-TOS.

Vitamin E analogues as anticancer agents: lessons from studies with alpha-tocopheryl succinate

The new millennium has witnessed considerable decrease in a number of previously fatal pathologies, largely due to the advancement in molecular medicine and modern approaches to treatment. In spite of this success, neoplastic disease remains a serious problem due to several reasons. These include an exceedingly high variability of cancer cells even within the same type of tumour. Cancer cells, albeit of clonal origin, mutate so that they escape established treatments, resulting in the fatal outcome of current therapies. Moreover, there are types of cancer, such as mesotheliomas, that cannot be treated at present. A novel group of clinically interesting anticancer drugs has been a recent focus in the literature that hold substantial promise as selective anticancer drugs. These compounds, epitomised by alpha-tocopheryl succinate, comprise redox-silent analogues of vitamin E that have been shown to suppress several types of cancer in animal models, including breast, colon and lung cancer as well as mesotheliomas and melanomas, while being nontoxic to normal cells and tissues. It is now proven that the strong anticancer effect of vitamin E analogues stems from their propensity to induce selective apoptosis in malignant cells. The results point to the novel group of vitamin E analogues as promising agents applicable to different types of tumours.

Benzo[a]pyrene impairs beta-adrenergic stimulation of adipose tissue lipolysis and causes weight gain in mice. A novel molecular mechanism of toxicity for a common food pollutant

Benzo[a]pyrene (B[a]P) is a common food pollutant that causes DNA adduct formation and is carcinogenic. The report of a positive correlation between human plasma B[a]P levels and body mass index, together with B[a]P's lipophilicity, led us to test for possible adverse effects of B[a]P on adipose tissue. In ex vivo experiments using primary murine adipocytes, B[a]P rapidly (within minutes) and directly inhibited epinephrine-induced lipolysis (up to 75%) in a dose-dependent manner. Half-maximum inhibition was obtained with a B[a]P concentration of 0.9 mg.L(-1) (3.5 microm). Lipolysis induced by beta(1)-, beta(2)- and beta(3)-adrenoreceptor-specific agonists, as well as ACTH, were also significantly inhibited by B[a]P, whereas forskolin-induced lipolysis was not B[a]P-sensitive. Similar inhibition of catecholamine-induced lipolysis by B[a]P was also seen in isolated human adipocytes; half-maximum inhibition of lipolysis was achieved with a B[a]P concentration of 0.02 mg.L(-1) (0.08 microm). In vivo treatment of C57Bl/6J mice with 0.4 mg.kg(-1) B[a]P inhibited epinephrine-induced release of free fatty acids by 70%. Chronic exposure of mice to B[a]P (0.5 mg.kg(-1) injected i.p. every 48 h) for 15 days also decreased lipolytic response to epinephrine and induced a 43% higher weight gain compared with controls (B[a]P: 2.23 +/- 0.12 g versus control: 1.56 +/- 0.18 g, P < 0.01) due to increased fat mass. The weight gain occurred consistently without detectable changes in food intake. These results reveal a novel molecular mechanism of toxicity for the environmental pollutant B[a]P and introduce the notion that chronic exposure of human population to B[a]P and possibly other polycyclic aromatic hydrocarbons could have an impact on metabolic disorders, such as obesity.

Tocotrienol inhibits proliferation of human Tenon's fibroblasts in vitro: a comparative study with vitamin E forms and mitomycin C

PURPOSE

To evaluate the potential of the vitamin E compound alpha-tocotrienol as antifibrotic agent in vitro.

METHODS

Using human Tenon's capsule fibroblast cultures, the antiproliferative and cytotoxic effects of the different vitamin E forms alpha-tocopherol, alpha-tocopheryl acetate, alpha-tocopheryl succinate and alpha-tocotrienol were compared with those of mitomycin C. To mimic subconjunctival and regular oral application in vivo, exposure time of serum-stimulated and serum-restimulated fibroblasts (SF and RF, respectively) to vitamin E forms was set at 6 days. Cultures were only exposed for 5 min to mitomycin C due to its known acute toxicity and to mimic the short-time intraoperative administration. Proliferation (expressed as % of control) was determined by DNA content quantification on days 2, 4 and 6, whereas cytotoxicity was assessed by cell morphology and glucose 6-phosphate dehydrogenase (G6PD) release after 24 h.

RESULTS

alpha-Tocopherol and alpha-tocopheryl acetate stimulated growth of SF, but not RF. Reduction of fibroblast content by alpha-tocopheryl succinate was accompanied by increased G6PD release and necrosis. Contrary to alpha-tocopheryl succinate, 50 microM or repeatedly 20 microM of alpha-tocotrienol significantly inhibited proliferation without causing cellular toxicity (maximal effect: 46.8%). RF were more sensitive to this effect than SF. Mitomycin C 100-400 microg/ml showed a stronger antiproliferative effect than alpha-tocotrienol (maximal effect: 13.8%). Morphologic characteristics of apoptosis were more commonly found under treatment with mitomycin C.

CONCLUSIONS

Of the vitamin E forms tested, only alpha-tocotrienol significantly inhibited growth at non-toxic concentrations. In this in vitro study, antiproliferative effects of mitomycin C were stronger than those of alpha-tocotrienol.

Chemopreventive effect of dietary d-alpha-tocopheryl succinate supplementation on precancer colon aberrant crypt formation and vitamin E analogue levels in young and old rats

This study examined the effects of dietary d-alpha-tocopheryl succinate (TS) in female rats, 20 mo (OLD) or 2 mo (YNG) of age, on azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) and tissue distribution of d-alpha-tocopherol (alphaT), d-gamma-tocopherol (gammaT), and alphaTS. Rats were fed a commercial rodent chow supplemented with or without 1 (YNG) or 2 (OLD) g alphaTS/kg diet for 1 week prior to ip administration of AOM to induce colon ACF. The animals were sacrificed after 49 days of exposure. The results showed that OLD rats had significantly fewer ACF than YNG animals, and the percent body fat and serum triglycerides were significantly higher in the OLD group compared with the YNG. However, only OLD animals receiving alphaTS had significantly reduced numbers of larger ACF and significantly higher levels of colonic alphaT, gammaT, and alphaTS. These data support previous studies demonstrating that dietary alphaTS administration is protective against intestinal cancer. Also, this is the first study to show that alphaTS accumulates in most tissues following dietary exposure. We hypothesize that increased colon accumulation of fat-soluble vitamin E compounds and subsequent chemoprevention may be related to greater percent body fat and serum triglycerides in OLD animals receiving dietary TS.

Inhibitory effects of polysaccharides isolated from Phellinus gilvus on benzo(a)pyrene-induced forestomach carcinogenesis in mice

AIM: Although polysaccharides from Phellinus mushrooms are a well-known material with anti-tumor properties, there is no information about the effect of polysaccharides from Phellinus gilvus (PG) on tumor. The modulating effect of polysaccharides isolated from PG on the benzo(a)pyrene (BaP)-induced forestomach carcinogenesis in ICR female mice was investigated in this study.

METHODS: A forestomach carcinogenesis model was established in 40 ICR female mice receiving oral administration of BaP for 4 wk. The mice were randomly assigned to 4 groups (10 each). The mice in each group were treated with sterile water or PG for 4 and 8 wk (SW4, PGW4, SW8, and PGW8 groups). Eight or 12 wk after the first dose of BaP, forestomachs were removed for histopathological and RT-PCR analysis.

RESULTS: In histopathological changes and RT-PCR analysis, sterile water-treated mice showed significant hyperplasia of the gastric mucosa with a significantly increased expression of mutant p53 mRNA compared to mice treated with PG for 8 wk.

CONCLUSION: Polysaccharides isolated from PG may inhibit BaP-induced forestomach carcinogenesis in mice bydown-regulating mutant p53 expression.

Pro-apoptotic mechanisms of action of a novel vitamin E analog (alpha-TEA) and a naturally occurring form of vitamin E (delta-tocotrienol) in MDA-MB-435 human breast cancer cells

Vitamin E derivative, RRR-alpha-tocopheryl succinate (vitamin E succinate, VES), is a potent pro-apoptotic agent, inducing apoptosis by restoring both transforming growth factor-beta (TGF-beta) and Fas (CD95) apoptotic signaling pathways that contribute to the activation of c-Jun N-terminal kinase (JNK)-mediated apoptosis. Objectives of these studies were to characterize signaling events involved in the pro-apoptotic actions of a naturally occurring form of vitamin E, delta-tocotrienol, and a novel vitamin E analog, alpha-tocopherol ether acetic acid analog [alpha-TEA; 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxyacetic acid]. Like VES, alpha-TEA and delta-tocotrienol induced estrogen-nonresponsive MDA-MB-435 and estrogen-responsive MCF-7 human breast cancer cells to undergo high levels of apoptosis in a concentration- and time-dependent fashion. Like VES, the two compounds induced either no or lower levels of apoptosis in normal human mammary epithelial cells and immortalized but nontumorigenic human MCF-10A cells. The pro-apoptotic mechanisms triggered by the structurally distinct alpha-TEA and delta-tocotrienol were identical to those previously reported for VES, that is, alpha-TEA- and delta-tocotrienol-induced apoptosis involved up-regulation of TGF-beta receptor II expression and TGF-beta-, Fas- and JNK-signaling pathways. These data provide a better understanding of the anticancer actions of a dietary form of vitamin E (delta-tocotrienol) and a novel nonhydrolyzable vitamin E analog (alpha-TEA).

Differential response of human ovarian cancer cells to induction of apoptosis by vitamin E Succinate and vitamin E analogue, alpha-TEA

A vitamin E derivative, vitamin E succinate (VES; RRR-alpha-tocopheryl succinate), and a vitamin E analogue, 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxy acetic acid (alpha-TEA), induce human breast, prostate, colon, lung, cervical, and endometrial tumor cells in culture to undergo apoptosis but not normal human mammary epithelial cells, immortalized, nontumorigenic breast cells, or normal human prostate epithelial cells. Human ovarian and cervical cancer cell lines are exceptions, with alpha-TEA exhibiting greater proapoptotic effects. Although both VES and alpha-TEA can induce A2780 and subline A2780/cp70 ovarian cancer cells to undergo DNA synthesis arrest within 24 h of treatment, only alpha-TEA is an effective inducer of apoptosis. VES or alpha-TEA treatment of cp70 cells with 5, 10, or 20 microg/ml for 3 days induced 5, 6, and 19% versus 9, 36, and 71% apoptosis, respectively. Colony formation data provide additional evidence that cp70 cells are more sensitive to growth inhibition by alpha-TEA than VES. Differences in stability of the ester-linked succinate moiety of VES versus the ether-linked acetic acid moiety of alpha-TEA were demonstrated by high-performance liquid chromatography analyses that showed alpha-TEA to remain intact, whereas VES was hydrolyzed to the free phenol, RRR-alpha-tocopherol. Pretreatment of cp70 cells with bis-(p-nitrophenyl) phosphate, an esterase inhibitor, before VES treatment, resulted in increased levels of intact VES and apoptosis. Taken together, these data show alpha-TEA to be a potent and stable proapoptotic agent for human ovarian tumor cells and suggest that endogenous ovarian esterases can hydrolyze the succinate moiety of VES, yielding RRR-alpha-tocopherol, an ineffective apoptotic-inducing agent.

Expression of estrogen receptor and estrogen receptor messenger RNA in gastric carcinoma tissues

AIM: To study estrogen receptor (ER) and estrogen receptor messenger RNA (ERmRNA) expression in gastric carcinoma tissues and to investigate their association with the pathologic types of gastric carcinoma.

METHODS: The expression of ER and ERmRNA in gastric carcinoma tissues (15 males and 15 females, 42-70 years old) was detected by immunohistochemistry and in situ hybridization, respectively.

RESULTS: The positive rate of ER (immunohistochemistry) was 33.3% in males and 46.7% in females. In Borrmann IV gastric carcinoma ER positive rate was greater than that in other pathologic types, and in poorly differentiated adenocarcinoma and signet ring cell carcinoma the positive rates were greater than those in other histological types of both males and females (P < 0.05). The ER was more highly expressed in diffused gastric carcinoma than in non-diffused gastric carcinoma (P < 0.05). The ER positive rate was also related to regional lymph nodes metastases (P < 0.05), and was significantly higher in females above 55 years old, and higher in males under 55 years old (P < 0.05). The ERmRNA (in situ hybridization) positive rate was 73.3% in males and 86.7% in females. The ERmRNA positive rates were almost the same in Borrmann I, II, III and IV gastric carcinoma (P > 0.05). ERmRNA was expressed in all tubular adenocarcinoma, poorly differentiated adenocarcinoma and signet ring cell carcinoma (P < 0.05). The ERmRNA positive rate was related to both regional lymph nodes metastases and gastric carcinoma growth patterns, and was higher in both sexes above 55 years old but without statistical significance (P > 0.05). The positive rate of ERmRNA expression by in situ hybridization was higher than that of ER expression by immunohistochemistry (P < 0.05).

CONCLUSION: ERmRNA expression is related to the pathological behaviors of gastric carcinoma, which might help to predict the prognosis and predict the effectiveness of endocrine therapy for gastric carcinoma.

Alpha-tocopheryl succinate, the most effective form of vitamin E for adjuvant cancer treatment: a review

In 1982, it was established that alpha-tocopheryl succinate (alpha-TS) was the most effective form of vitamin E in comparison to alpha-tocopherol, alpha-tocopheryl acetate and alpha-tocopheryl nicotinate in inducing differentiation, inhibition of proliferation and apoptosis in cancer cells, depending upon its concentration. During the last two decades, several studies have confirmed this observation in rodent and human cancer cells in culture and in vivo (animal model). The most exciting aspect of this alpha-TS effect is that it does not affect the proliferation of most normal cells. In spite of several studies published on the anti-cancer properties of alpha-TS, the value of this form of vitamin E has not drawn significant attention from researchers and clinicians. Therefore, a critical review on the potential role of alpha-TS in the management of cancer is needed. In addition, such a review can also provide in-depth analysis of existing literature on this subject. alpha-TS treatment causes extensive alterations in gene expression; however, only some can be attributed to differentiation, inhibition of proliferation and apoptosis. alpha-TS also enhances the growth-inhibitory effect of ionizing radiation, hyperthermia, some chemotherapeutic agents and biological response modifiers on tumor cells, while protecting normal cells against some of their adverse effects. Thus, alpha-TS alone or in combination with dietary micronutrients can be useful as an adjunct to standard cancer therapy by increasing tumor response and possibly decreasing some of the toxicities to normal cells.

Tributyrin inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest

AIM

To evaluate the effects of tributyrin, a pro-drug of natural butyrate and a neutral short-chain fatty acid triglyceride, on the growth inhibition of human gastric cancer SGC-7901 cell.

METHODS

Human gastric cancer SGC-7901 cells were exposed to tributyrin at 0.5, 1, 2, 5, 10 and 50 mmol/L(-1) for 24-72 h. MTT assay was applied to detect the cell proliferation. [(3)H]-TdR uptake was measured to determine DNA synthesis. Apoptotic morphology was observed by electron microscopy and Hoechst-33258 staining. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect tributyrin-triggered apoptosis. The expressions of PARP, Bcl-2 and Bax were examined by Western blot assay.

RESULTS

Tributyrin could initiate growth inhibition of SGC-7901 cell in a dose- and time-dependent manner. [(3)H]-TdR uptake by SGC-7901 cells was reduced to 33.6 % after 48 h treatment with 2 mmol/L(-1) tributyrin, compared with the control (P<0.05). Apoptotic morphology was detected by TUNEL assay. Flow cytometry revealed that tributyrin could induce apoptosis of SGC-7901 cells in dose-dependent manner. After 48 hours incubation with tributyrin at 2 mmol/L(-1), the level of Bcl-2 protein was lowered, and the level of Bax protein was increased in SGC-7901, accompanied by PARP cleavage.

CONCLUSION

Tributyrin could inhibit the growth of gastric cancer cells effectively in vitro by inhibiting DNA synthesis and inducing apoptosis, which was associated with the down-regulated Bcl-2 expression and the up-regulated Bax expression. Therefore, tributyrin might be a promising chemopreventive and chemotherapeutic agent against human gastric carcinogenesis.

Inhibition of conjugated linoleic acid on mouse forestomach neoplasia induced by benzo (a) pyrene and chemopreventive mechanisms

AIM: To explore the inhibition of conjugated linoleic acid isomers in different purity (75% purity c9, t11-, 98% purity c9, t11- and 98% purity t10,c12-CLA) on the formation of forestomach neoplasm and cheopreventive mechanisms.

METHODS: Forestomach neoplasm model induced by B (a) P in KunMing mice was established. The numbers of tumor and diameter of each tumor in forestomach were counted; the mice plasma malondialdehyde (MDA) were measured by TBARS assay; TUNEL assay was used to analyze the apoptosis in forestomach neoplasia and the expression of MEK-1, ERK-1, MKP-1 protein in forestomach neoplasm were studied by Western Blotting assay.

RESULTS: The incidence of neoplasm in B (a) P group, 75% purity c9,t11-CLA group, 98% purity c9,t11-CLA group and 98% purity t10,c12-CLA group was 100%, 75.0% (P > 0.05), 69.2% (P < 0.05) and 53.8% (P < 0.05) respectively and the effect of two CLA isomers in 98% purity on forestomach neoplasia was significant; CLA showed no influence on the average tumor numbers in tumor-bearing mouse, but significantly decreased the tumor size, the tumor average diameter of mice in 75% purity c9,t11-CLA group, 98% purity c9,t11-CLA group and 98% purity t10,c12-CLA group was 0.157 ± 0.047 cm, 0.127 ± 0.038 cm and 0.128 ± 0.077 cm (P < 0.05) and 0.216 ± 0.088 cm in B (a) P group; CLA could also significantly increase the apoptosis cell numbers by 144.00 ± 20.31, 153.75 ± 23.25, 157.25 ± 15.95 (P < 0.05) in 75% purity c9,t11-CLA group, 98% purity c9,t11-CLA group and 98% purity t10,c12-CLA group (30.88 ± 3.72 in BP group); but there were no significant differences between the effects of 75% purity c9,t11-CLA and two isomers in 98% purity on tumor size and apoptotic cell numbers; the plasma levels of MDA in were increased by 75% purity c9,t11-CLA, 98% purity c9,t11-CLA and 98% purity t10,c12-CLA. The 75% purity c9,t11-CLA showed stronger inhibition; CLA could also inhibit the expression of ERK-1 protein and promote the expression of MKP-1 protein, however no influence of CLA on MEK-1 protein was observed.

CONCLUSION: Two isomers in 98% purity show stronger inhibition on carcinogenesis. However, the inhibitory mechanisms of CLA on carcinogenesis is complicated, which may be due to the increased mice plasma MDA, the inducing apoptosis in tumor tissues. And the effect of CLA on the expression of ERK-1 and MKP-1 may be one of the mechanisms of the inhibition of CLA on the tumor.

Vitamin E and breast cancer prevention: current status and future potential

Vitamin E is a collective term used to refer to a number of structurally and functionally different compounds. Although some vitamin E compounds are popular supplements marketed for their potential beneficial antioxidant effects for a number of chronic diseases including various forms of cancer, a recent report by the National Academy of Sciences Food and Nutrition Board concluded that too little is known at present to provide definitive answers regarding whether taking larger doses of dietary antioxidants will help prevent chronic diseases. Recent reviews of epidemiological data suggest that dietary source vitamin E may provide some protection against breast cancer, while vitamin E supplements do not. A majority of studies investigating the protective effects of certain types of vitamin E in animal models of mammary cancer prevention conclude that there is little or no effect. The study of vitamin E is complex, and the vitamin E field faces many scientific challenges.

Effect of apoptosis on gastric adenocarcinoma cell line SGC-7901 induced by cis-9, trans-11-conjugated linoleic acid

AIM: To determine the effect of apoptosis on gastric cancer cells (SGC-7901) induced by cis-9, trans-11-conjugated linoleic acid (c9, t11-CLA) and its possible mechanism in the inhibition of cancer cells growth.

METHODS: Using cell culture, flow cytometery and immunocytochemical techniques, we examined the cell growth, frequency of apoptosis and distribution of cell cycle, expression of ki67, bcl-2, Fas, and c-myc of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 μmol·L^-1) of c9, t11-CLA for 24 h and 48 h, with a negative control (0.1% ethanol).

RESULTS: The growth of SGC-7901 cells was inhibited by c9,t11-CLA. Eight days after treatment with various concentrations of c9,t11-CLA, as mentioned above, the inhibition rates were 5.9%, 20.2%, 75.6% and 82.4%, respectively. The frequency of apoptosis on SGC-7901 cells induced by different concentrations of c9, t11-CLA (except for 25 μmol·L^-1, 24 h) was significantly greater than that in the negative control (P < 0.01). To further investigate the influence of the cell cycle progression, we found that apoptosis induced by c9, t11-CLA may be involved in blocking the cell cycle of SGC-7901 cells. Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations for various time periods significantly decreased the expressions of ki67 (the expression rates were 18.70%-3.20%, at 24 h and 8.10%-0.20% at 48 h, respectively), bcl-2 (4.30%-0.15% at 24 h and 8.05%-0% at 48 h),and c-myc (4.85%-2.20% at 24 h and 4.75%-0.30% at 48 h) as compared with those in the controls (the expressions of ki67, bcl-2, and c-myc were 15.1% at 24 h and 13.5% at 48 h, 6.80% at 24 h and 8.00% at 48 h, 5.50% at 24 h and 5.30% at 48 h, respectively) (P < 0.01), whereas the expressions of Fas were increased (0.60%-2.75%, 24 h and 0.45%-5.95%, 48 h).

CONCLUSION: The growth and proliferation of SGC-7901 cells are inhibited by c9, t11-CLA via blocking the cell cycle, pathways of bcl-2-associated mitochondria with reduced expression of bcl-2 and Fas-associated death domain protein (FADD) with enhanced expression of Fas. But expression of c-myc on SGC-7901 cells is lower than that in negative control, which needs to be studied further.

Roles of Fas signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells

AIM

To investigate the roles of Fas signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells.

METHODS

Human gastric cancer SGC-7901 cells were treated with VES at 5, 10, 20 mg x L(-1), succinic acid and vitamin E as vehicle control and condition media only as untreated (UT) control. Apoptotic morphology was observed by DAPI staining. Western blot analysis was applied to measure the expression of Fas, FADD and caspase-8 proteins. After the cells were transiently transfected with Fas and FADD antisense oligonucleotides, respectively, caspase-8 activity was determined by flurometric method.

RESULTS

The morphologically apoptotic changes were observed after VES treatment by DAPI staining. 23.7 % and 89.6 % apoptosis occurred after 24 h and 48 h of 20 mg x L(-1) VES treatment, respectively. The protein levels of Fas, FADD and caspase-8 were evidently increased in a dose-dependent manner after 24 h of VES treatment. The blockage of Fas by transfection with Fas antisense oligonucleotides obviously inhibited the expression of FADD protein. After SGC-7901 cells were transfected with Fas and FADD antisense oligonucleotides, caspase-8 activity was obviously decreased (P<0.01), whereas Fas blocked more than FADD.

CONCLUSION

VES-induced apoptosis in human gastric cancer SGC-7901 cells involves Fas signaling pathway including the interaction of Fas, FADD and caspase-8.

The effects of vitamin E succinate on the expression of c-jun gene and protein in human gastric cancer SGC-7901 cells

AIM

To investigate the effects of vitamin E succinate (VES) on the expression of c-jun gene and protein in human gastric cancer SGC-7901 cells.

METHODS

After SGC-7901 cells were treated with VES at different doses (5,10,20 mg x L(-1)) at different time, reverse transcription-PCR technique was used to detect the level of c-jun mRNA; Western Blot was applied to measure the expression of c-jun protein.

RESULTS

After the cells were treated with VES at 20 mg x L(-1) for 3 h, the expression rapidly reached its maximum that was 3.5 times of UT control (P<0.01). The level of c-jun mRNA was also increased following treatment of VES for 6 h. However,the expression after treatment of VES at 5 mg x L(-1) for 24 h was 1.6 times compared with UT control (P<0.01). Western blot analysis showed that the level of c-jun protein was obviously elevated in VES-treated SGC-7901 cells at 20 mg x L(-1) for 3 h. The expression of c-jun protein was gradually increased after treatment of VES at 20 mg x L(-1) for 3, 6, 12 and 24 h, respectively, with an evident time-effect relationship.

CONCLUSION

The levels of c-jun mRNA and protein in VES-treated SGC-7901 cells were increased in a dose- and time-dependent manner; the expression of c-jun was prolonged by VES, indicating that c-jun is involved in VES-induced apoptosis in SGC-7901 cells.

Effect of cis-9, trans-11-conjugated linoleic acid on cell cycle of gastric adenocarcinoma cell line (SGC-7901)

AIM

To determine the effect of cis -9, trans -11-conjugated linoleic acid (c9, t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth.

METHODS

Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B(1), D(1), p16(ink4a) and p21(cip/waf1) of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 micromol.L(-1))of c 9, t 11-CLA for 24 and 48h, with a negative control (0.1% ethane).

RESULTS

The cell growth and DNA synthesis of SGC-7901 cells were inhibited by c9, t11-CLA.SGC-7901 cells. Eight day after treatment with various concentrations of c9, t11-CLA mentioned above, the inhibition rates were 5.92%, 20.15%, 75.61% and 82.44%, respectively and inhibitory effect of c9, t11-CLA on DNA synthesis (except for 25 micromol.L, 24h) showed significantly less (3)H-TdR incorporation than that in the negative controls (P<0.05 and P<0.01). Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations at various times significantly decreased the expressions of PCNA (the expression rates were 7.2-3.0%, 24h and 9.1-0.9% at 48h, respectively), Cyclin A (11.0-2.3%, 24h and 8.5-0.5%,48h), B(1) (4.8-1.8% at 24h and 5.5-0.6% at 48h)and D(1) (3.6-1.4% at 24h and 3.7%-0 at 48h) as compared with those in the negative controls(the expressions of PCNA, Cyclin A, B(1) and D(1) were 6.5% at 24h and 9.0% at 48h, 4.2% at 24h and 5.1% at 48h, 9.5% at 24h and 6.0% at 48h,respectively)(P<0.01), whereas the expressions of P16(ink4a) and P21(cip/waf1), cyclin-dependent kinases inhibitors(CDKI), were increased.

CONCLUSION

The cell growth and proliferation of SGC-7901 cell is inhibited by c9, t11-CLA via blocking the cell cycle, with reduced expressions of cyclin A,B(1) and D(1) and enhanced expressions of CDKI(P16(ink4a) and p21(cip/waf1)).

RRR-alpha-tocopheryl succinate inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest

AIM

To investigate the effects of growth inhibition of human gastric cancer SGC-7901 cell with RRR-alpha-tocopheryl succinate (VES), a derivative of natural Vitamin E, via inducing apoptosis and DNA synthesis arrest.

METHODS

Human gastric cancer SGC-7901 cells were regularly incubated in the presence of VES at 5, 10 and 20mg x L(-1) (VES was dissolved in absolute ethanol and diluted in RPMI 1640 complete condition media correspondingly to a final concentration of VES and 1 mL x L(-1) ethanol), succinic acid and ethanol equivalents as vehicle (VEH) control and condition media only as untreated (UT) control. Trypan blue dye exclusion analysis and MTT assay were applied to detect the cell proliferation. Cells were pulsed with 37kBq of tritiated thymidine and (3H) TdR uptake was measured to observe DNA synthesis. Apoptotic morphology was observed by electron microscopy and DAPI staining. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect VES-triggered apoptosis.

RESULTS

VES inhibited SGC-7901 cell growth in a dose-dependent manner. The growth curve showed suppression by 24.7%, 49.2% and 68.7% following 24h of VES treatment at 5, 10 and 20 mg x L(-1), respectively, similar to the findings from MTT assay. DNA synthesis was evidently reduced by 35%, 45% and 98% after 24h VES treatment at 20mg x L(-1) and 48 h at 10 and 20mg x L(-1), respectively. VES induced SGC-7901 cells to undergo apoptosis with typically apoptotic characteristics, including morphological changes of chromatin condensation, chromatin crescent formation/margination, nucleus fragmentation and apoptotic body formation, typical apoptotic sub-G1 peak by flow cytometry and increase of apoptotic cells by TUNEL assay in which 90% of cells underwent apoptosis after 48 h of VES treatment at 20 mg x L(-1).

CONCLUSION

VES can inhibit human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest. Inhibition of SGC-7901 cell growth by VES is dose- and time-dependent. Therefore VES can function as a potent chemotherapeutic agent against human gastric carcinogenesis.