Man Hui Pai

Concomitant supplementation of lycopene and eicosapentaenoic acid inhibits the proliferation of human colon cancer cells

Several studies indicated that people who live in the Mediterranean region have very low rates of chronic diseases such as cardiovascular disease and cancer. It is well known that Mediterranean-style diet is rich in vegetables, tomato, fruit, fish and olive oil. These important dietary components may contribute to lower risk of cancer. Lycopene, a major component in tomato, exhibited potential anticarcinogenic activity. Previous studies showed that consumption of fish containing eicosapentaenoic acid (EPA) correlated with reduced risk of cancer. However, the combined effects of lycopene and EPA on the proliferation of human colon cancer have not been studied well yet. Thus, we investigated the anticancer properties and therapeutic potential of lycopene and EPA in human colon cancer HT-29 cells. In this study, we determined the combined effects of lycopene and EPA on the proliferation of human colon cancer HT-29 cells. We demonstrated that low concentration of lycopene and EPA could synergistically inhibit the proliferation of colon cancer cells. The inhibitory mechanism was associated with suppression of phosphatidylinositol 3-kinase/Akt signaling pathway. Furthermore, treatment of lycopene and EPA also synergistically blocked the activation of downstream mTOR molecule. Immunocytochemical staining results revealed that lycopene and EPA could also up-regulate the expression of apoptotic proteins such as Bax and Fas ligand to suppress cell survival. In conclusion, our novel findings suggest that lycopene and EPA synergistically inhibited the growth of human colon cancer HT-29 cells even at low concentration. The inhibitory effects of lycopene and EPA on cell proliferation of human colon cancer HT-29 cells were, in part, associated with the down-regulation of the PI-3K/Akt/mTOR signaling pathway.

Glutamine administration ameliorates sepsis-induced kidney injury by downregulating the high-mobility group box protein-1-mediated pathway in mice

Acute kidney injury (AKI) is a severe complication of sepsis. High-mobility group box (HMGB)-1 was implicated as a late mediator of lethal systemic inflammation in sepsis. Since glutamine (GLN) was shown to have anti-inflammatory and antioxidant properties, we hypothesized that GLN administration may downregulate an HMGB-1-mediated pathway and thus ameliorate sepsis-induced AKI. Mice were randomly assigned to a normal group (NC), a septic saline group (SS), or a septic GLN group (SG). Sepsis was induced by cecal ligation and puncture (CLP). The SS group was injected with saline, and the SG group was given 0.75 g GLN/kg body wt once via a tail vein 1 h after CLP. Mice were killed 2, 6, and 24 h after CLP, and blood and kidneys of the animals were harvested for further analysis. The results showed that sepsis resulted in higher mRNA and/or protein expressions of kidney HMGB-1, toll-like receptor (TLR) 4, myeloid differentiation primary-response protein (MyD) 88, and receptor of advanced glycation end products (RAGE) compared with normal mice. Septic mice with GLN administration exhibited decreased HMGB-1, TLR4, RAGE, and phosphorylated NF-κB p65 protein expressions and reduced nitrotyrosine levels in kidney tissues. The histological findings showed that damage to the kidneys was less severe, and survival improved in the SG group. These results indicated that a single dose of GLN administered after the initiation of sepsis plays a prophylactic role in downregulating the expressions of HMGB-1-related mediators and decreasing oxidative stress in the kidneys, which may consequently have ameliorated AKI induced by sepsis.

Caffeic Acid Derivatives Inhibit the Growth of Colon Cancer: Involvement of the PI3-K/Akt and AMPK Signaling Pathways

Background The aberrant regulation of phosphatidylinositide 3-kinases (PI3-K)/Akt, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (m-TOR) signaling pathways in cancer has prompted significant interest in the suppression of these pathways to treat cancer. Caffeic acid (CA) has been reported to possess important anti-inflammatory actions. However, the molecular mechanisms by which CA derivatives including caffeic acid phenethyl ester (CAPE) and caffeic acid phenylpropyl ester (CAPPE), exert inhibitory effects on the proliferation of human colorectal cancer (CRC) cells have yet to be elucidated. Methodology/Principal Findings CAPE and CAPPE were evaluated for their ability to modulate these signaling pathways and suppress the proliferation of CRC cells both in vitro and in vivo. Anti-cancer effects of these CA derivatives were measured by using proliferation assays, cell cycle analysis, western blotting assay, reporter gene assay and immunohistochemical (IHC) staining assays both in vitro and in vivo. This study demonstrates that CAPE and CAPPE exhibit a dose-dependent inhibition of proliferation and survival of CRC cells through the induction of G0/G1 cell cycle arrest and augmentation of apoptotic pathways. Consumption of CAPE and CAPPE significantly inhibited the growth of colorectal tumors in a mouse xenograft model. The mechanisms of action included a modulation of PI3-K/Akt, AMPK and m-TOR signaling cascades both in vitro and in vivo. In conclusion, the results demonstrate novel anti-cancer mechanisms of CA derivatives against the growth of human CRC cells. Conclusions CA derivatives are potent anti-cancer agents that augment AMPK activation and promote apoptosis in human CRC cells. The structure of CA derivatives can be used for the rational design of novel inhibitors that target human CRC cells.

Consumption of high-fat diet induces tumor progression and epithelial-mesenchymal transition of colorectal cancer in a mouse xenograft model.

Epidemiologic studies suggest that intake of high-fat diet (HFD) promotes colon carcinogenesis. Epithelial-mesenchymal transition (EMT) and inflammation play important roles during tumor progression of colorectal cancer (CRC). Oncogenic pathways such as phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR and mitogen-activated protein kinase (MAPK)/ERK signaling cascades induce EMT and inflammation in cancer. No experimental evidence has been demonstrated regarding HFD-mediated tumor progression including EMT in CRC so far. Our results demonstrated that HFD consumption could induce tumor growth and progression, including EMT and inflammation, in a mouse xenograft tumor model. The molecular mechanisms were through activation of MAPK/ERK and PI3K/Akt/mTOR signaling pathways. HFD induced up-regulation of cyclooxygenase-2, cyclin D1 and proliferating cell nuclear antigen proteins concomitant with increases in expression of nuclear factor-κB p65 (RelA) and β-catenin proteins. Surprisingly, HFD consumption could suppress p21(CIP1/WAF1) expression through increases in nuclear histone deacetylase complex (HDAC). Moreover, HFD could mediate the disassembly of E-cadherin adherent complex and the up-regulation of Vimentin and N-cadherin proteins in tumor tissues. Taken together, our novel findings support evidence for HFD-mediated modulation of HDAC activity and activation of oncogenic cascades, which involve EMT and inflammation in CRC, playing important roles in tumor growth and progression in a mouse xenograft model.

Pretreatment with alanyl-glutamine suppresses T-helper-cell-associated cytokine expression and reduces inflammatory responses in mice with acute DSS-induced colitis

T-helper (Th) cells play a major role in initiating and shaping the pathologic response in inflammatory bowel disease (IBD). Glutamine (GLN) is a nutrient with immune-modulating effects. This study investigated the effect of GLN on cytokine expressions and inflammatory responses of three subsets of Th cells in dextran sulfate sodium (DSS)-induced IBD. There were one normal control (NC) and two DSS groups. Mice in the DSS groups drank distilled water containing 3% DSS for 5 days, whereas the NC group received distilled water. Mice in the G-DSS group were given intraperitoneal injection of 0.5 g GLN/kg/d for 3 days before receiving DSS water. The other DSS group (C-DSS) received an identical amount of amino acid solution without GLN. After induction of IBD, the mice were allowed to recover for 3 days and then were sacrificed. Blood and colon samples were collected for further analysis. The C-DSS group had higher percentages of blood interleukin (IL)-17A, IL-17F, IL-22, IL-4 and interferon-γ than the NC group. The G-DSS group had lower Th1/Th17/Th2 cytokine expressions, which showed no differences from the NC group. Plasma haptoglobin, colon immunoglobin G and chemokine levels and myeloperoxidase activities were higher in the DSS groups than the NC group. These parameters were significantly lower in the G-DSS than the C-DSS group. These results suggest that pretreatment with GLN suppressed Th-associated cytokine expressions and may consequently reduce inflammatory mediator production and leukocyte infiltration into tissues, thus ameliorating the severity of acute DSS-induced colitis.

Consumption of S-allylcysteine inhibits the growth of human non-small-cell lung carcinoma in a mouse xenograft model.

Lung cancer is one of the leading causes of cancer death in the world. Human non-small-cell lung carcinoma (NSCLC) accounts for almost 80% of lung cancer cases. Aberrant phosphoinositide 3-kinase (PI3K)/Akt/mTOR signaling pathways play important roles and have been widely observed in the development of NSCLC. Previous studies indicated that garlic extracts such as diallyl disulfide (DADS) and diallyl trisulfide (DATS) could inhibit the proliferation of several types of cancer in vitro. However, the inhibitory effects of S-allylcysteine (SAC) on the growth of NSCLC have not been demonstrated yet. Therefore, this study investigated whether consumption of SAC could prevent the growth of NSCLC in both in vitro and in vivo models. It was found that SAC significantly inhibited the proliferation of human NSCLC A-549 cells in vitro. Treatment of the NF-κB inhibitor, Bay-11-7082, could significantly inhibit the proliferation of NSCLC A-549 cells. The results demonstrated that SAC significantly suppressed the activation of mTOR, NF-κB, and cyclin D1 molecules in vitro. Furthermore, the results demonstrated that consumption of SAC significantly inhibited the growth of highly metastatic human NSCLC cells in tumor-bearing mice. Bioluminescence imaging and pathological and immunohistochemical (IHC) staining results also indicated that SAC could effectively suppress the growth and malignant progression of human NSCLC in vivo. The chemopreventive effects of SAC were associated with suppression of mTOR and NF-κB molecules in vivo. These results suggested that SAC could act as an effective agent against the malignant progression of human NSCLC in both in vitro and in vivo models.

Organosulfur garlic compounds induce neovasculogenesis in human endothelial progenitor cells through a modulation of MicroRNA 221 and the PI3-K/Akt signaling pathways

Human endothelial progenitor cells (EPCs) play crucial roles in the prevention of ischemic injury via neovasculogenesis. Frequent garlic consumption is reportedly associated with a low incidence of cardiovascular diseases (CVD). However, the molecular mechanisms by which garlic extracts, including diallyl disulfide (DADS) and diallyl trisulfide (DATS), exert an effect on neovasculogenesis have not been elucidated yet. The current study investigated the effects of these organosulfur compounds on neovasculogenesis by using vascular tube formation assay, Western blotting assay, real-time polymerase chain reaction (RT-PCR), and immunohistochemical (IHC) staining assays in both in vitro and in vivo models. The current study demonstrates that DADS and DATS dose-dependently enhance the neovasculogenesis of human EPCs in vitro. The mechanism of actions included the up-regulation of the c-kit protein, as well as the phosphorylation (i.e., activation) of the Akt and ERK 1/2 signaling molecules in human EPCs. Furthermore, DATS suppressed the expression of microRNA (miR) 221 in vitro. In a mouse xenograft model of neovasculogenesis, DATS consumption induced the formation of new blood vessels at a dosage of 10 mg/kg of body weight/day. It is suggested that garlic consumption enhances neovasculogenesis in human EPCs and thereby probably exerts a preventive effect against ischemic injuries.

Effect of arginine on angiogenesis induced by human colon cancer: In vitro and in vivo studies

This study investigated the effect of arginine (Arg) supplementation on angiogenesis in human colon cancer. The in vitro study investigated the effects of different Arg levels and inducible nitric oxide (iNO) synthase inhibitor on angiogenic protein expressions stimulated by SW480 cells. The results showed that the production of vascular endothelial growth factor (VEGF), basic fibroblast growth factor with 100 and 1000 micromol/L Arg and matrix metalloproteinase (MMP)-2 with 1000 micromol/L Arg was lower than that with 0 and 50 micromol/L Arg. Inhibition of iNO resulted in higher angiogenic protein expressions comparable with groups with low Arg administration, indicating that Arg administration at levels similar to or higher than physiological concentrations reduced the progression of colon cancer, and iNO may partly play a role in reducing angiogenesis. The in vivo study used a human colon cancer xenograft model in nude mice. Mice were inoculated with 1x10(7) SW480 cells and assigned to two groups. The control group was fed a semipurified diet, while the experimental group was supplied an Arg-supplemented diet. After 5 weeks, tumors were harvested and spleens were excised for further analysis. Results showed that the MMP-2, MMP-9 and VEGF receptor levels in tumors were significantly lower, whereas tumor NO levels and spleen natural killer (NK) cell activities were higher in the Arg group than in the control group. These results were consistent with the in vitro study that dietary Arg supplementation inhibits the progression of colon cancer possibly by increasing NO secretion and consequently enhancing NK cell activity.

S-Allylcysteine inhibits tumour progression and the epithelial-mesenchymal transition in a mouse xenograft model of oral cancer

Oral cancer is prevalent worldwide. Studies have indicated that an increase in the osteopontin (OPN) plasma level is correlated with the progression of oral cancer. Our previous report showed that the aqueous garlic extract S-allylcysteine (SAC) inhibited the epithelial-mesenchymal transition (EMT) of human oral cancer CAL-27 cells in vitro. Therefore, the present study investigated whether SAC consumption would help prevent tumour growth and progression, including the EMT, in a mouse xenograft model of oral cancer. The results demonstrated that SAC dose-dependently inhibited the growth of oral cancer in tumour-bearing mice. The histopathological and immunohistochemical staining results indicated that SAC was able to effectively suppress the tumour growth and progression of oral cancer in vivo. The chemopreventive effect of SAC was associated with the suppression of carcinogenesis factors such as N-methylpurine DNA glycosylase and OPN. SAC significantly suppressed the phosphorylation of Akt, mammalian target of rapamycin, inhibitor of κBα and extracellular signal-regulated kinase 1/2 in tumour tissues. The results demonstrated that the SAC-mediated suppression of cyclin D1 protein was associated with an augmented expression of the cell-cycle inhibitor p16(Ink4). Furthermore, SAC inhibited the expression of cyclo-oxygenase-2, vimentin and NF-κB p65 (RelA). These results show that SAC has potential as an agent against tumour growth and the progression of oral cancer in a mouse xenograft model.

Glutamine administration modulates lung γδ T lymphocyte expression in mice with polymicrobial sepsis.

ABSTRACT This study investigated the effects of glutamine (GLN) administration on regulating lung &ggr;&dgr; T cells in polymicrobial sepsis. Mice were randomly assigned to normal group (NC), septic saline group (SS), and septic GLN group (SG). All mice were fed with chow diet. Sepsis was induced by cecal ligation and puncture (CLP). The SS and SG groups were, respectively, injected with saline and 0.75 g GLN/kg body weight once via tail vein 1 h after CLP. Mice were killed 12 and 24 h after CLP. Their lungs were collected for further analysis. The results showed that, compared with normal mice, sepsis resulted in higher lung &ggr;&dgr; T cell and neutrophil percentages and higher cytokine expressed by &ggr;&dgr; T cells. Histopathologic findings showed that the extent of inflammatory lesions of the lung alveolar was less severe in the SG group than the SS group after CLP. The SG group had a higher &ggr;&dgr; T cell percentage and lower &ggr;&dgr; T cell apoptotic rates as well as lower neutrophil numbers in the lungs. Also, interleukin 17A (IL-17A), interferon &ggr;, and IL-10 expressed by &ggr;&dgr; T cells and CXC receptor 2 expressed by neutrophils decreased in the SG group. Moreover, GLN reduced IL-17A, IL-1&bgr;, and IL-23 concentrations and myeloperoxidase activity in lung tissues. Our results suggest that GLN administration after initiation of sepsis affects lung &ggr;&dgr; T cell percentage and cytokine secretion and prevented apoptosis of &ggr;&dgr; T cells and neutrophil infiltration to the lungs, which may partly be responsible for ameliorating acute lung injury induced by sepsis.