Deepak Poudyal

Resveratrol suppresses colitis and colon cancer associated with colitis

Resveratrol is a naturally occurring polyphenol that exhibits pleiotropic health beneficial effects, including anti-inflammatory, cardio-protective, and cancer-protective activities. It is recognized as one of the more promising natural molecules in the prevention and treatment of chronic inflammatory and autoimmune disorders. Ulcerative colitis is an idiopathic, chronic inflammatory disease of the colon associated with a high colon cancer risk. Here, we used a dextran sulfate sodium (DSS) mouse model of colitis, which resembles human ulcerative colitis pathology. Resveratrol mixed in food ameliorates DSS-induced colitis in mice in a dose-dependent manner. Resveratrol significantly improves inflammation score, downregulates the percentage of neutrophils in the mesenteric lymph nodes and lamina propria, and modulates CD3+ T cells that express tumor necrosis factor-α and IFN-γ. Markers of inflammation and inflammatory stress (p53 and p53-phospho-Ser15) are also downregulated by resveratrol. Because chronic colitis drives colon cancer risk, we carried out experiments to determine the chemopreventive properties of resveratrol. Tumor incidence is reduced from 80% in mice treated with azoxymethane (AOM) + DSS to 20% in mice treated with AOM + DSS + resveratrol (300 ppm). Tumor multiplicity also decreased with resveratrol treatment. AOM + DSS–treated mice had 2.4 ± 0.7 tumors per animal compared with AOM + DSS + 300 ppm resveratrol, which had 0.2 ± 0.13 tumors per animal. The current study indicates that resveratrol is a useful, nontoxic complementary and alternative strategy to abate colitis and potentially colon cancer associated with colitis. Cancer Prev Res; 3(4); 549–59. ©2010 AACR.

Suppression of colitis in mice by Cl-amidine: a novel peptidylarginine deiminase inhibitor

Inflammatory bowel diseases (IBDs), mainly Crohns disease and ulcerative colitis, are dynamic, chronic inflammatory conditions that are associated with an increased colon cancer risk. Inflammatory cell apoptosis is a key mechanism for regulating IBD. Peptidylarginine deiminases (PADs) catalyze the posttranslational conversion of peptidylarginine to peptidylcitrulline in a calcium-dependent, irreversible reaction and mediate the effects of proinflammatory cytokines. Because PAD levels are elevated in mouse and human colitis, we hypothesized that a novel small-molecule inhibitor of the PADs, i.e., chloramidine (Cl-amidine), could suppress colitis in a dextran sulfate sodium mouse model. Results are consistent with this hypothesis, as demonstrated by the finding that Cl-amidine treatment, both prophylactic and after the onset of disease, reduced the clinical signs and symptoms of colitis, without any indication of toxic side effects. Interestingly, Cl-amidine drives apoptosis of inflammatory cells in vitro and in vivo, providing a mechanism by which Cl-amidine suppresses colitis. In total, these data help validate the PADs as therapeutic targets for the treatment of IBD and further suggest Cl-amidine as a candidate therapy for this disease.

Suppression of colitis-driven colon cancer in mice by a novel small molecule inhibitor of sphingosine kinase

Sphingolipid metabolism is driven by inflammatory cytokines. These cascade of events include the activation of sphingosine kinase (SK), and subsequent production of the mitogenic and proinflammatory lipid sphingosine 1-phosphate (S1P). Overall, S1P is one of the crucial components in inflammation, making SK an excellent target for the development of new anti-inflammatory drugs. We have recently shown that SK inhibitors suppress colitis and hypothesize here that the novel SK inhibitor, ABC294640, prevents the development of colon cancer. In an azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model, there was a dose-dependent decrease in tumor incidence with SK inhibitor treatment. The tumor incidence (number of animals with tumors per group) in the vehicle, ABC294640 (20 mg/kg) and ABC294640 (50 mg/kg) groups were 80, 40 and 30%, respectively. Tumor multiplicity (number of tumors per animal) also decreased from 2.1 ± 0.23 tumors per animal in the AOM + DSS + vehicle group to 1.2 ± 0 tumors per animal in the AOM + DSS + ABC294640 (20 mg/kg) and to 0.8 ± 0.4 tumors per animal in the AOM + DSS + ABC294640 (50 mg/kg) group. Importantly, with ABC294640, there were no observed toxic side effects. To explore mechanisms, we isolated cells from the colon (CD45-, representing primarily colon epithelial cells) and (CD45+, representing primarily colon inflammatory cells) then measured known targets of SK that control cell survival. Results are consistent with the hypothesis that the inhibition of SK activity by our novel SK inhibitor modulates key pathways involved in cell survival and may be a viable treatment strategy for the chemoprevention colitis-driven colon cancer.

American Ginseng Suppresses Colitis through p53-Mediated Apoptosis of Inflammatory Cells

Ulcerative colitis is a dynamic, chronic inflammatory condition associated with an increased colon cancer risk. Inflammatory cell apoptosis is a key mechanism regulating ulcerative colitis. American ginseng (AG) is a putative antioxidant that can suppress hyperactive immune cells. We have recently shown that AG can prevent and treat mouse colitis. Because p53 levels are elevated in inflammatory cells in both mouse and human colitis, we tested the hypothesis that AG protects from colitis by driving inflammatory cell apoptosis through a p53 mechanism. We used isogenic p53+/+ and p53−/− inflammatory cell lines as well as primary CD4+/CD25− effector T cells from p53+/+ and p53−/− mice to show that AG drives apoptosis in a p53-dependent manner. Moreover, we used a dextran sulfate sodium (DSS) model of colitis in C57BL/6 p53+/+ and p53−/− mice to test whether the protective effect of AG against colitis is p53 dependent. Data indicate that AG induces apoptosis in p53+/+ but not in isogenic p53−/− cells in vitro. In vivo, C57BL/6 p53+/+ mice are responsive to the protective effects of AG against DSS-induced colitis, whereas AG fails to protect from colitis in p53−/− mice. Furthermore, terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling of inflammatory cells within the colonic mesenteric lymph nodes is elevated in p53+/+ mice consuming DSS + AG but not in p53−/− mice consuming DSS + AG. Results are consistent with our in vitro data and with the hypothesis that AG drives inflammatory cell apoptosis in vivo, providing a mechanism by which AG protects from colitis in this DSS mouse model. Cancer Prev Res; 3(3); 339–47

A multi-targeted approach to suppress tumor-promoting inflammation.

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

A Key Role of microRNA-29b for the Suppression of Colon Cancer Cell Migration by American Ginseng

Metastasis of colon cancer cells increases the risk of colon cancer mortality. We have recently shown that American ginseng prevents colon cancer, and a Hexane extract of American Ginseng (HAG) has particularly potent anti-inflammatory and anti-cancer properties. Dysregulated microRNA (miR) expression has been observed in several disease conditions including colon cancer. Using global miR expression profiling, we observed increased miR-29b in colon cancer cells following exposure to HAG. Since miR-29b plays a role in regulating the migration of cancer cells, we hypothesized that HAG induces miR-29b expression to target matrix metalloproteinase-2 (MMP-2) thereby suppressing the migration of colon cancer cells. Results are consistent with this hypothesis. Our study supports the understanding that targeting MMP-2 by miR-29b is a mechanism by which HAG suppresses the migration of colon cancer cells.

A Hexane Fraction of American Ginseng Suppresses Mouse Colitis and Associated Colon Cancer: Anti-inflammatory and Proapoptotic Mechanisms

Ulcerative colitis is a chronic inflammatory condition associated with a high colon cancer risk. We have previously reported that American ginseng extract significantly reduced the inflammatory parameters of chemically induced colitis. The aim of this study was to further delineate the components of American ginseng that suppress colitis and prevent colon cancer. Among five different fractions of American ginseng (butanol, hexane, ethylacetate, dichloromethane, and water), a hexane fraction has particularly potent antioxidant and proapoptotic properties. The effects of this fraction were shown in a mouse macrophage cell line (ANA-1 cells), in a human lymphoblastoid cell line (TK6), and in an ex vivo model (CD4+/CD25− primary effector T cells). A key in vivo finding was that compared with the whole American ginseng extract, the hexane fraction of American ginseng was more potent in treating colitis in a dextran sodium sulfate (DSS) mouse model, as well as suppressing azoxymethane/DSS-induced colon cancer. Furthermore, terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling (TUNEL) labeling of inflammatory cells within the colonic mesenteric lymph nodes was elevated in mice consuming DSS + the hexane fraction of American ginseng. Results are consistent with our in vitro data and with the hypothesis that the hexane fraction of American ginseng has anti-inflammatory properties and drives inflammatory cell apoptosis in vivo, providing a mechanism by which this fraction protects from colitis in this DSS mouse model. This study moves us closer to understanding the molecular components of American ginseng that suppress colitis and prevent colon cancer associated with colitis. Cancer Prev Res; 5(4); 685–96. ©2012 AACR.

Mechanistic insight into the ability of American ginseng to suppress colon cancer associated with colitis

We have recently shown that American ginseng (AG) prevents and treats mouse colitis. Because both mice and humans with chronic colitis have a high colon cancer risk, we tested the hypothesis that AG can be used to prevent colitis-driven colon cancer. Using the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of ulcerative colitis, we show that AG can suppress colon cancer associated with colitis. To explore the molecular mechanisms of the anticancer effects of AG, we also carried out antibody array experiments on colon cells isolated at a precancerous stage. We found there were 82 protein end points that were either significantly higher (41 proteins) or significantly lower (41 proteins) in the AOM + DSS group compared with the AOM-alone (control) group. In contrast, there were only 19 protein end points that were either significantly higher (10 proteins) or significantly lower (9 proteins) in the AOM + DSS + AG group compared with the AOM-alone (control) group. Overall, these results suggest that AG keeps the colon environment in metabolic equilibrium when mice are treated with AOM + DSS and gives insight into the mechanisms by which AG protects from colon cancer associated with colitis.

Suppression of DNA damage in human peripheral blood lymphocytes by a juice concentrate: A randomized, double‐blind, placebo‐controlled trial

Chronic inflammation contributes to many prevalent diseases worldwide, and it is widely accepted that inflammatory molecules contribute to DNA damage. In this ancillary study, we investigated the influence of an encapsulated fruit and vegetable juice powder concentrate on peripheral blood lymphocytes (PBL) DNA damage. Using a double-blind, placebo-controlled approach, subjects were randomly assigned capsules containing placebo, or one of two formulations of the juice powder. Blood was drawn at baseline and after 60 days of capsule consumption. We found DNA damage in isolated PBL is suppressed after consumption of the encapsulated juice powder, and damage was correlated with the level of systemic inflammation. These data suggest a potential health benefit by consuming the juice concentrate capsules through their ability to suppress DNA damage as measured in surrogate tissues (PBL).

A Limited Role of p53 on the Ability of a Hexane Fraction of American Ginseng to Suppress Mouse Colitis

Ulcerative colitis (UC) is debilitating and carries a high colon cancer risk. Apoptosis of inflammatory cells is a key mechanism regulating UC. We have recently shown that American ginseng (AG), and to a greater extent, a Hexane fraction of AG (HAG) can cause apoptosis and suppress mouse colitis through a p53-mediated mechanism. Here, we tested the hypothesis that HAG suppresses colitis through a p53 mechanism. We found only a limited impact of p53 in the ability of HAG to induce inflammatory cell apoptosis and suppress mouse colitis in vitro and in vivo. Finally, we asked whether HAG could cause cell cycle arrest of HCT116 colon cancer cells in vitro. Interestingly, HAG caused a G1 arrest of such cells independent of p53 status. Findings are significant because HAG suppresses colitis and associated colon cancer, and mutation in p53 is observed in most colitis-driven colon cancers. Therefore, HAG might be very effective in targeting the inflammatory cells and cancer cells since it induces apoptosis of inflammatory cells and cell cycle arrest in both p53−/− and WT p53 colon cancer cells.