The involvement of AMPK/GSK3-beta signals in the control of metastasis and proliferation in hepato-carcinoma cells treated with anthocyanins extracted from Korea wild berry Meoru.

BACKGROUND: Activation of the Wnt pathway is known to promote tumorigenesis and tumor metastasis, and targeting Wnt pathway inhibition has emerged as an attractive approach for controlling tumor invasion and metastasis. The major pathway for inhibiting Wnt is through the degradation of ß-catenin by the GSK3-beta/CK1/Axin/APC complex. It was found that Hep3B hepato-carcinoma cells respond to anthocyanins through GSK3-beta-induced suppression of beta-catenin; however, they cannot dephosphorylate GSK3-beta without AMPK activation. METHODS: We tested the effects of anthocyanins on proliferation and apoptosis by MTT and Annexin V-PI staining in vitro. Mouse xenograft models of hepato-carcinomas were established by inoculation with Hep3B cells, and mice were injected with 50 mg/kg/ml of anthocyanins. In addition, protein levels of p-GSK3-beta, beta-catenin, p-AMPK, MMP-9, VEGF, and Ang-1 were also analyzed using western blot. RESULTS: Anthocyanins decrease phospho-GSK3-beta and beta-catenin expression in an in vivo tumor xenograft model, increase AMPK activity in this model, and inhibit cell migration and invasion, possibly by inhibiting MMP-2 (in vitro) and the panendothelial marker, CD31 (in vivo). To elucidate the role of the GSK3-beta/beta-catenin pathway in cancer control, we conditionally inactivated this pathway, using activated AMPK for inhibition. Further, we showed that AMPK siRNA treatment abrogated the ability of anthocyanins to control cell proliferation and metastatic potential, and Compound C, an AMPK inhibitor, could not restore GSK3-beta regulation, as exhibited by anthocyanins in Hep3B cells. CONCLUSION: These observations imply that the AMPK-mediated GSK3-beta/beta-catenin circuit plays crucial roles in inhibiting cancer cell proliferation and metastasis in anthocyanin-treated hepato-carcinoma cells of Meoru origin.

Cryptotanshinone induces ER stress-mediated apoptosis in HepG2 and MCF7 cells.

The endoplasmic reticulum (ER) is a central organelle in eukaryotic cells that functions in protein synthesis and maturation, and also functions as a calcium storage organelle. Perturbation of ER functions leads to ER stress, which has been previously associated with a broad variety of diseases. ER stress is generally regarded as compensatory, but prolonged ER stress can activate apoptotic pathways in damaged cells. For this reason, pharmacological interventions that effectively enhance tumor death through ER stress have been the subject of a great deal of attention for anti-cancer therapy. Cryptotanshinone, the major active constituent isolated from the root of Salvia miltiorrhiza Bunge, has been recently evaluated for its anti-cancer activity, but the molecular mechanisms underlying these activities remain poorly understood. In particular, it remains completely unknown as to whether or not cryptotanshinone can induce ER stress. Herein, we identify cryptotanshinone as a potent stimulator of ER stress, leading to apoptosis in many cancer cell lines, including HepG2 hepatoma and MCF7 breast carcinoma, and also demonstrate that mitogen-activated protein kinases function as mediators in this process. Reactive oxygen species generated by cryptotanshinone have been shown to play a critical role in ER stress-induced apoptosis. Cryptotanshinone also evidenced sensitizing effects to a broad range of anti-cancer agents including Fas/Apo-1, TNF-α, cisplatin, etoposide or 5-FU through inducing ER stress, highlighting the therapeutic potential in the treatment of human hepatoma and breast cancer.

Suppression of mTOR via Akt-dependent and -independent mechanisms in selenium-treated colon cancer cells: involvement of AMPKalpha1.

Activation of the mammalian target of rapamycin (mTOR) pathway promotes tumorigenesis, and inhibiting the mammalian target of rapamycin complex 1 (mTORC1) has emerged as an attractive target for suppressing tumor growth. We found that selenium treatment of HT-29 colon cancer cells suppressed mTORC1 through Akt-independent and -dependent pathways. In Akt-independent mTORC1 inhibition in selenium-treated colon cancer cells, adenosine monophosphate-activated protein kinase (AMPK) alpha(1) was crucial for suppression of mTORC1 activity. In contrast, the Akt-dependent mTORC1 inhibition by selenium did not require AMPKalpha(1). The importance of the AMPKalpha(1)-mTORC1 pathway in mediating the antiproliferative action of selenium was examined in xenograft tumors, and the suppression of mTORC1 as well as Akt was concomitant with an increase in AMPKalpha(1) activity. These findings suggest that the antiproliferative effect of selenium is mediated by an Akt-independent AMPKalpha(1)/mTORC1 pathway or by the Akt/tuberous sclerosis complex 2 /mTORC1 pathway.

AMP kinase/cyclooxygenase-2 pathway regulates proliferation and apoptosis of cancer cells treated with quercetin.

AMPK (AMP-activated protein kinase) is highly conserved in eukaryotes, where it functions primarily as a sensor of cellular energy status. Recent studies indicate that AMPK activation strongly suppresses cell proliferation in non-malignant cells as well as in tumor cells. In this study, quercetin activated AMPK in MCF breast cancer cell lines and HT-29 colon cancer cells, and this activation of AMPK seemed to be closely related to a decrease in COX-2 expression. The application of a COX-2 inhibitor or cox-2-/- cells supported the idea that AMPK is an upstream signal of COX-2, and is required for the anti-proliferatory and pro-apoptotic effects of quercetin. The suppressive or growth inhibitory effects of quercetin on COX-2 were abolished by treating cancer cells with an AMPK inhibitor Compound C. These results suggest that AMPK is crucial to the anti-cancer effect of quercetin and that the AMPK-COX-2 signaling pathway is important in quercetin-mediated cancer control.

Genistein Inhibits Proliferation of BRCA1 Mutated Breast Cancer Cells: The GPR30-Akt Axis as a Potential Target.

BACKGROUND: BRCA1 mutated breast cancer cells exhibit the elevated cell proliferation and the higher metastatic potential. G protein-coupled receptor 30 (GPR30) has been shown to regulate growth of hormonally responsive cancers, such as ovarian and breast cancers, and high expression of GPR30 is found in estrogen receptor (ER)-negative breast cancer cells. ER-negative breast cancer patients often have a mutation in the tumor suppressor gene, BRCA1. This study explored antiproliferative effects of genistein, a chemopreventive isoflavone present in legumes, and underlying molecular mechanisms in triple negative breast cancer cells with or without functionally active BRCA1. METHODS: Expression of BRCA1, GPR30 and Nrf2 was measured by Western blot analysis. Reactive oxygen species (ROS) accumulation was monitored by using the fluorescence-generating probe, 2',7'-dichlorofluorescein diacetate. The effects of genistein on breast cancer cell viability and proliferation were assessed by the MTT, migration and clonogenic assays. RESULTS: The expression of GPR30 was dramatically elevated at both transcriptional and translational levels in BRCA1 mutated breast cancer cells compared to cells with wild-type BRCA1. Notably, there was diminished Akt phosporylation in GPR30 silenced cells. Treatment of BRCA1 silenced breast cancer cells with genistein resulted in the down-regulation of GPR30 expression and the inhibition of Akt phosphorylation as well as the reduced cell viability, migration and colony formation. Genistein caused cell cycle arrest at the G2/M phase in BRCA1-mutant cells through down-regulation of cyclin B1 expression. Furthermore, BRCA1-mutant breast cancer cells exhibited higher levels of intracellular ROS than those in the wild-type cells. Genistein treatment lowered the ROS levels through up-regulation of Nrf2 expression. CONCLUSIONS: Lack of functional BRCA1 activates GPR30 signaling, thereby stimulating Akt phosphorylation and cell proliferation. Genistein induces G2/M phase arrest by down-regulating cyclin B1 expression, which is attributable to its suppression of GPR30 activation and Akt phosphorylation in BRCA1 impaired breast cancer cells.

Selenium regulates cyclooxygenase-2 and extracellular signal-regulated kinase signaling pathways by activating AMP-activated protein kinase in colon cancer cells.

Epidemiologic and experimental evidences indicate that selenium, an essential trace element, can reduce the risk of a variety of cancers. Protection against certain types of cancers, particularly colorectal cancers, is closely associated with pathways involving cyclooxygenase-2 (COX-2). We found that AMP-activated protein kinase (AMPK), which functions as a cellular energy sensor, mediates critical anticancer effects of selenium via a COX-2/prostaglandin E(2) signaling pathway. Selenium activated AMPK in tumor xenografts as well as in colon cancer cell lines, and this activation seemed to be essential to the decrease in COX-2 expressions. Transduction with dominant-negative AMPK into colon cancer cells or application of cox-2(-/-)-negative cells supported the evidence that AMPK is an upstream signal of COX-2 and inhibits cell proliferation. In HT-29 colon cancer cells, carcinogenic agent 12-O-tetradecanoylphorbol-13-acetate (TPA) activated extracellular signal-regulated kinase (ERK) that led to COX-2 expression and selenium blocked the TPA-induced ERK and COX-2 activation via AMPK. We also showed the role of a reactive oxygen species as an AMPK activation signal in selenium-treated cells. We propose that AMPK is a novel and critical regulatory component in selenium-induced cancer cell death, further implying AMPK as a prime target of tumorigenesis.

Apoptotic effect of EGCG in HT-29 colon cancer cells via AMPK signal pathway.

EGCG [(-)epigallocatechin-3-gallate], a green tea-derived polyphenol, has been shown to suppress cancer cell proliferation, and interfere with the several signaling pathways and induce apoptosis. Practically, there is emerging evidence that EGCG has a potential to increase the efficacy of chemotherapy in patients. We hypothesized that EGCG may exert cell cytotoxicity through modulating AMPK (AMP-activated protein kinase) followed by the decrease in COX-2 expression. EGCG treatment to colon cancer cells resulted in a strong activation of AMPK and an inhibition of COX-2 expression. The decreased COX-2 expression as well as prostaglandin E(2) secretion by EGCG was completely abolished by inhibiting AMPK by an AMPK inhibitor, Compound C. Also, the activation of AMPK was accompanied with the reduction of VEGF (vascular endothelial growth factor) and glucose transporter, Glut-1 in EGCG-treated cancer cells. These findings support the regulatory role of AMPK in COX-2 expression in EGCG-treated cancer cells. Furthermore, we have found that reactive oxygen species (ROS) is an upstream signal of AMPK, and the combined treatment of EGCG and chemotherapeutic agents, 5-FU or Etoposide, exert a novel therapeutic effect on chemo-resistant colon cancer cells. AMPK, a molecule of newly defined cancer target, was shown to control COX-2 in EGCG-treated colon cancer cells.

Attenuation of Abeta-induced apoptosis of plant extract (Saengshik) mediated by the inhibition of mitochondrial dysfunction and antioxidative effect.

Recently, considerable attention has been focused on dietary manipulation of oxidative and/or nitrosative damage on neuronal cells. In this article, a neuroprotective effect of plant (Saengshik) extracts was investigated. Rat pheochromocytoma (PC12), cells treated with beta-amyloid underwent apoptotic death as determined by positive in situ terminal end-labeling (TUNEL staining), decreased mitochondrial transmembrane potential, and elevated caspase-3 activity co-occurring with enhanced MDA accumulation and the reduction of GSH levels. Saengshik pretreatment attenuated beta-amyloid-induced apoptosis in PC12 cells possibly by inhibiting mitochondrial dysfunction and exerting antioxidant properties. Saengshik pretreatment inhibited the loss of mitochondrial membrane potentials and reduced the activation of caspase-3. The in vitro antioxidant activities of Saengshik extracts were verified by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and superoxide dismutase (SOD) mimetic activity. In beta-amyloid-challenged PC12 cells, Saengshik prevented the production of ROS, decreased the level of MDA, and elevated GSH. The potential of Saengshik as one of the neuroprotective regimens has been suggested through this article, and the combination with defined pharmaceuticals or other dietary antioxidants may provide a better therapeutic or preventive advantage for the management of Alzheimer's disease.

Resveratrol induces apoptosis in chemoresistant cancer cells via modulation of AMPK signaling pathway.

Resveratrol has been reported to possess therapeutic effects for various cancers including colon cancers. In this article, the molecular basis of resveratrol with emphasis on its ability to control intracellular signaling cascades of adenosine monophosphate (AMP)-activated protein kinase (AMPK) responsible for inducing apoptosis in drug-resistant cancer cells was investigated. Recently, the evolutionarily conserved serine/threonine kinase, AMPK, emerges as a possible target molecule of cancer control. We have investigated the effects of resveratrol on apoptosis in relation to AMPK in HT-29 cells shown chemoresistant to a cancer chemotherapeutic drug, etoposide. Resveratrol exhibited a variety of molecular events in etoposide-based combination therapy in HT-29 colon cancer cells including the AMPK activation, inhibition of cell growth, induction of apoptosis, and reactive oxygen species (ROS) generation. The involvement of AMPK signaling cascade in resveratrol-based cancer therapy was clearly shown by comparing the conditions of AMPK activated states and inactivated states. We have identified ROS as an upstream regulator of AMPK. Further investigation warrants to elucidate the mechanism by which resveratrol generates ROS and AMPK activation.

Involvement of AMPK signaling cascade in capsaicin-induced apoptosis of HT-29 colon cancer cells.

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is activated during ATP-depleting metabolic states, such as hypoxia, heat shock, oxidative stress, and exercise. As a highly conserved heterotrimeric kinase that functions as a major metabolic switch to maintain energy homeostasis, AMPK has been shown to exert as an intrinsic regulator of mammalian cell cycle. Moreover, AMPK cascade has emerged as an important pathway implicated in cancer control. In this article, we have investigated the effects of capsaicin on apoptosis in relation to AMPK activation in colon cancer cell. Capsaicin-induced apoptosis was revealed by the presence of nucleobodies in the capsaicin-treated HT-29 colon cancer cells. Concomitantly, the activation of AMPK and the increased expression of the inactive form of acetyl-CoA carboxylase (ACC) were detected in capsaicin-treated colon cancer cells. We showed that both capsaicin and 5'-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR), an AMPK activator possess the AMPK-activating capacity as well as apoptosis-inducing properties. Evidence of the association between AMPK activation and the increased apoptosis in HT-29 colon cancer cells by capsaicin treatment, and further findings of the correlation of the activated AMPK and the elevated apoptosis by cotreatment of AICAR and capsaicin support AMPK as an important component of apoptosis, as well as a possible target of cancer control.

Possible link between NO concentrations and COX-2 expression in systems treated with soy-isoflavones.

The production of nitric oxide (NO) emerges as an essential determinant in auto- and paracrine signaling. NO is known to be generated under inflammatory conditions, carcinogenesis, and circulatory shock. The large amount of NO produced in response to cytokines plays an important role in inflammatory conditions. Cyclooxygenase (COX), the central enzyme in prostanoid biosynthesis, is involved in the first step of prostanoid synthesis from arachidonic acid. The reported studies to evaluate the relationship between NO and COX-2 have revealed both inhibitory and stimulatory effects of NO on COX-2 expression. Genistein, one of soy-isoflavones, is a polyphenolic flavonoid and a potent antioxidant and anti-inflammatory agent. In the present article, the effect of soy-isoflavones on NO production and COX-2 gene expression was examined. NO production by soy-isoflavones was greatly increased even though eNOS and iNOS expression were not different from nontreated control. The increment of NO was accompanied with the elevated expression of COX-2 and the concentrations of PGE2. The COX-2 stimulatory effect of soy-isoflavones appeared to be modulated by ERK-1 and -2 and p38. In mammalian cancer system, incubation with the NO donor sodium nitroprusside (SNP) resulted in a slight upregulation of COX-2, and cotreatment with genistein decreased COX-2 expression possibly by the activation of AMP-activated protein kinase (AMPK).

Differential modulation of AMPK signaling pathways by low or high levels of exogenous reactive oxygen species in colon cancer cells.

This study was undertaken to examine the effect of low and high concentrations of H2O2 on cancer cell proliferation and apoptosis, and AMPK signaling pathways in HT-29 human colon cancer cells. Nontoxic doses of H2O2 (10 microM) induced cancer cell proliferation, whereas the toxic level of 1,000 microM H2O2 induced apoptosis. The stimulation of cell proliferation was accompanied with an increase in cyclooxygenase-2 (COX-2), and apoptosis induced by high-dose H2O2 was correlated with the activation of AMPK and negatively correlated with COX-2 expression. These results suggest that ROS at nontoxic levels can stimulate cancer cell growth by regulating AMP-activated protein kinase (AMPK) and/or COX-2, and the abundant exogenous ROS linked to the growth inhibition through modulating AMPK signaling pathways.

AMPK interacts with ß-catenin in the regulation of hepatocellular carcinoma cell proliferation and survival with selenium treatment.

Selenium has received much attention as an anticancer agent, although the mechanisms of action underlying its pro-apoptotic properties remain unclear. Tumors that respond well to antioxidant treatments, such as hepatocellular carcinoma (HCC), may benefit from treatment with selenium as this compound also has antioxidant properties. Furthermore, a major oncogenic driver in HCC is the nuclear transcription co-activator, ß-catenin. In the present study, we examined the mechanism by which selenium reduces survival of HCC cells, and whether this was associated with modulation of the ß-catenin pathway. Hep3B cell lines and cancer cell xenografted animals were treated with selenium, and apoptotic events or signals such as AMPK, ß-catenin and GSK3ß were determined. Further interactions among ß-catenin, glycogen synthase kinase 3ß (GSK3ß), and AMPK were explored by applying AMPK small interfering RNA (siRNA) or GSK3ß siRNA with western blotting or immunofluorescence microscopic observation. Selenium activated AMPK, which in turn suppressed ß-catenin. Selenium induced the translocation of AMPK into the nucleus and prevented the accumulation of ß-catenin therein. Upon inactivation of AMPK by AMPK siRNA, selenium no longer modulated ß-catenin, implying that AMPK is an upstream signal for ß-catenin. We found that the binding between AMPK and ß-catenin occurs in the cytosolic fraction, and therefore concluded that the cancer cell antiproliferative effects of selenium are mediated by a GSK3ß-independent AMPK/ß-catenin pathway, although AMPK-mediated GSK3ß regulation was also observed. We primarily discovered that AMPK is a crucial regulator initiating selenium-induced inhibition of ß-catenin expression. Taken together, these novel findings help to illuminate the molecular mechanisms underlying the anticancer effect of selenium and highlight the regulation of ß-catenin by selenium.

Soy isoflavone supplementation alleviates oxidative stress and improves systolic blood pressure in male spontaneously hypertensive rats.

The aim of this study was to investigate the protective effect of isoflavone against hypertension, via the mitigation of oxidative stress and prevention of nitric oxide (NO, a potent vasodilator) reduction, in spontaneously hypertensive rats (SHR). The 8 wk-old male SHR were divided into two groups, and fed a casein-based high fat diet (120 g fat, 1 g cholesterol/kg diet) for 30 d, either with or without 10 g of soy powder (containing 31.2% of isoflavones)/kg. During the 30-d study period, tail systolic blood pressures (BP) in the control SHR group increased, from 162.4 +/- 2.3 to 177.9 +/- 5.4 mmHg (p<0.05), while the isoflavone-supplemented group benefited from a clear antihypertensive effect (160.1 +/- 1.8 to 160.2 +/- 4.9 mmHg). The serum NO and total radical trapping antioxidant potential (TRAP) were elevated in the isoflavone group. The isoflavone group also experienced a significant decrease in oxidative DNA damage in leukocytes, using comet assay. DNA damage correlated positively with incremental BP during the study, and systolic BP at the end of the study (p<0.01). Our results indicate that soy isoflavone has an antihypertensive effect, possibly through the amelioration of oxidative stress, and the augmentation of NO production, in SHR.

Proapoptotic potentials of genistein under growth stimulation by estrogen.

In mammary carcinogenesis, hormonal effects have been reported to be important factors. Estrogens are known to regulate the proliferation of breast cancer cells, whereas genistein has been shown to induce apoptosis in mammary tumor cells. This study examined genistein-induced apoptosis through the regulation of bcl-2 and bax expression in the presence of estrogen. MCF-7 cells were treated with either genistein (25, 50, and 100 microM) or in the presence of 17beta-estradiol (12.5, 25, and 50 nM) for 48 h. DNA ladder analysis and Western blot analysis of bcl-2, bax, cyclin B(1), p21, and p53 were carried out. For comparison, the in vivo system was employed using estrogen-deficient and estrogen-sufficient female rats at two different concentrations of genistein. In MCF-7 cells, DNA fragmentation was evident by the treatment of genistein in the absence and presence of estrogen. Downregulation of bcl-2 and upregulation of bax by genistein were observed. However, genistein showed no proapoptotic properties in the presence of estrogen except with the lowest concentration of estrogen. In the presence of estrogen, p21 and p53 protein expression were upregulated by high concentrations of genistein. Bcl-2/bax ratios were decreased by genistein treatment in the presence or absence of estrogen in female rats. These results demonstrate that the proapoptotic property of genistein might be influenced greatly by the concentration of estrogen in vitro, but that this influence by estrogen is not evident in vivo.

Chemopreventive potential of epigallocatechin gallate and genistein: evidence from epidemiological and laboratory studies.

A wide array of antioxidative and anti-inflammatory substances derived from edible plants have been reported to possess chemopreventive and chemoprotective activities. Among the most extensively investigated and well-defined dietary chemopreventives are epigallocatechin gallate (EGCG), a principal antioxidant derived from green tea and genistein, a major pharmacologically active isoflavone widely present in soy products. Multiple lines evidence from epidemiologic studies indicate that frequent consumption of green tea is inversely associated with the risk of several types of human cancer, and studies with animal and in vitro cell culture models have revealed EGCG as a major chemopreventive ingredient of green tea. The lower frequencies of breast and prostate cancer in Asian population in general, compared to those in Western societies have been attributed to their consumption of relatively large amounts of soy products. Genistein, as a principal chemopreventive components of soy, exerts a wide array of chemopreventive activities in each stage of multistep carcinogenesis. The purpose of this review is to provide perspectives on the molecular basis of chemopreventive activities of EGCG and geneistein as representative functional food phytochemicals with emphasis on their ability to control intracellular signaling cascades responsible for regulating cell growth and differentiation.

Nutritional status, iron-deficiency-related indices, and immunity of female athletes.

Nutritional status, iron-deficiency-related biochemical indices, and immunologic patterns of female Judo athletes and control subjects were evaluated. The subjects' 3-d food records showed that 41.0 kcal/kg of energy was consumed daily and the contributions of protein, fat, and carbohydrate to total energy intake were 12.5%, 29.2%, and 58.3%, respectively. The reported vitamin intakes of athletic subjects were above those of the recommended daily allowance, however, calcium and iron intakes were less than 100% of the recommended daily allowance. Intakes of energy, protein, phosphate, vitamin B1, and vitamin B2 were higher in the athletes than in the control subjects. Analysis using the Nutrient Adequacy Ratio and the Index of Nutritional Quality showed that athletic subjects had more desirable patterns than the control subjects. There was no any indication of anemia, which often occurs as a result of hemodilution in strenuously trained athletes. The subjects' immunologic patterns showed a slight immunosuppression. Iron, vitamin B1, niacin intakes were positively correlated with immunoglobulin (Ig) G levels in the athletes. The relation between nutrient intakes and the immune systems of endurance-trained athletes needs further investigation.

Comparison of estrogen and genistein in their antigenotoxic effects, apoptosis and signal transduction protein expression patterns.

The antigenotoxic effects of estrogen and genistein (isoflavones) were compared by measuring the degree of protection against plasmid DNA strand breakage induced by peroxyl free radicals using the DNA strand scission assay with pBR322 DNA. Isoflavones decreased DNA strand breakage by AAPH radical treatment at the all of three concentrations tested (0.5, 1.0, 1.5 microg/ml) with the range of 89.5% to 99.6%. Compared to genistein, estrogen was not as effective as genistein showing 46.9% to 29.6% protection, and this protective effect was decreased as estrogen concentrations increased from 0.1 to 0.3 microg/ml. DNA ladder experiments showed that genistein induced apoptosis in cultured cell lines, whereas estrogen did not induce any apoptosis. The effects of cell signal trandsduction protein expression patterns were compared between estrogen and genistein. The increased expression of cyclin B1 by estrogen was tampered by genistein at the highest concentration. Antigenotoxic and antiproliferative effects of genistein shown in this study support the hypothesis that it has a chemopreventive effect against particular types of cancers.

Effect of vitamin E supplementation on antioxidant defense systems and humoral immune responses in young, middle-aged and elderly Korean women.

Free radical-mediated oxidative stress has been implicated in the pathogenesis of numerous chronic diseases. Vitamin E is known to play an important role in the free-radical quenching process. However, clinical trials with vitamin E have yielded contrasting results in the prevention of several diseases related to oxidative stress. This study was undertaken to investigate the antioxidative and humoral immunologic effects of vitamin E supplementation in three different age groups: young (mean age 32.7 +/- 5.7 y), middle-aged (mean age 47.0 +/- 5.0 y) and elderly (67.6 +/- 4.7 y) women. Volunteer subjects were given a supplement of 400 IU dl-alpha-tocopherol acetate for 6 wk. Thiobarbituric acid reacting substances (TBARS) in the plasma significantly decreased with vitamin E supplementation. In addition, the radical scavenger activities (RSA) of red blood cells significantly increased with vitamin E supplementation in all age groups. However, humoral immune response modulation was not observed following vitamin E supplementation. Even though there is no clear indication that vitamin E supplementation is necessary to improve the humoral immune functions, vitamin E supplementation may be beneficial to all adult age groups as a preventive measure for complications related to oxidative damage.

Resistant starch supplementation influences blood lipid concentrations and glucose control in overweight subjects.

Resistant starch (RS) includes the sum of starch and degradation products of starch that resist small intestinal digestion and enter the colon. This study was planned to examine the effect of resistant starch on hypolipidemic actions, blood glucose, insulin levels and humoral immune responses in healthy overweight subjects. Healthy overweight subjects (over 120% of their ideal body weights) were fed either 24 g/d of resistant corn starch (RS) or regular corn starch (CS) for 21 d with their regular meals. Although this double-blind feeding regiment resulted in no significant changes in their weights or other physical parameters for the relatively acute period of intakes, there were significant lowering effects of serum total cholesterol (p < 0.05) and serum LDL-cholesterol (p < 0.05) in subjects supplemented RS. Compared with the control starch group, the RS supplementation also reduced the mean fasting serum glucose concentrations (p < 0.05). Resistant starch supplement resulted in the increase in serum immunoglobulin G (IgG) concentrations. Serum insulin and complement 3 (C3) were unaffected. Tested resistant starch supplementation was reported to be palatable with minimal bowel discomfort. These results suggest that RS supplementation improves the blood lipid profile and controls the blood glucose levels in healthy overweight subjects without bowel discomfort. Therefore, RS has a potential to be used as one of the promising food ingredients for reducing risk factors involved in the development of atherosclerosis and type 2 diabetes in overweight individuals. However, in order to prove RS as a novel therapeutic agent of cardiovascular diseases and diabetes, controlled trials with larger sample sizes and longer duration are warranted.