British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

The emerging role of the Nrf2-Keap1 signaling pathway in cancer

The Nrf2–Keap1 signaling pathway is key to cell defense and survival pathways. Nrf2 can protect cells and tissues from toxicants and carcinogens, and several Nrf2 activators are currently being tested as chemopreventive compounds. However, several studies also suggest that Nrf2 may protect cancer cells from chemotherapeutic agents and promote cancer cell proliferation. Here, Jaramillo and Zhang provide an overview of the Nrf2–Keap1 signaling pathway in cancer. They discuss the dual role of Nrf2 in cancer and the challenges in developing Nrf2-based drugs for chemoprevention and therapy.

The Nrf2 (nuclear factor erythroid 2 [NF-E2]-related factor 2 [Nrf2])–Keap1 (Kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1) signaling pathway is one of the most important cell defense and survival pathways. Nrf2 can protect cells and tissues from a variety of toxicants and carcinogens by increasing the expression of a number of cytoprotective genes. As a result, several Nrf2 activators are currently being tested as chemopreventive compounds in clinical trials. Just as Nrf2 protects normal cells, studies have shown that Nrf2 may also protect cancer cells from chemotherapeutic agents and facilitate cancer progression. Nrf2 is aberrantly accumulated in many types of cancer, and its expression is associated with a poor prognosis in patients. In addition, Nrf2 expression is induced during the course of drug resistance. Collectively, these studies suggest that Nrf2 contributes to both intrinsic and acquired chemoresistance. This discovery has opened up a broad spectrum of research geared toward a better understanding of the role of Nrf2 in cancer. This review provides an overview of (1) the Nrf2–Keap1 signaling pathway, (2) the dual role of Nrf2 in cancer, (3) the molecular basis of Nrf2 activation in cancer cells, and (4) the challenges in the development of Nrf2-based drugs for chemoprevention and chemotherapy.

Role of the microenvironment in the pathogenesis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver tumor and the third greatest cause of cancer-related death worldwide, and its incidence is increasing. Despite the significant improvement in management of HCC over the past 30 years, there are no effective chemoprevention strategies, and only one systemic therapy has been approved for patients with advanced tumors. This drug, sorafenib, acts on tumor cells and the stroma. HCC develops from chronically damaged tissue that contains large amounts of inflammation and fibrosis, which also promote tumor progression and resistance to therapy. Increasing our understanding of how stromal components interact with cancer cells and the signaling pathways involved could help identify new therapeutic and chemopreventive targets.

Anthocyanins and their role in cancer prevention

Anthocyanins are the most abundant flavonoid constituents of fruits and vegetables. The conjugated bonds in their structures, which absorb light at about 500 nm, are the basis for the bright red, blue and purple colors of fruits and vegetables, as well as the autumn foliage of deciduous trees. The daily intake of anthocyanins in residents of the United States is estimated to be about 200 mg or about 9-fold higher than that of other dietary flavonoids. In this review, we summarize the latest developments on the anti-carcinogenic activities of anthocyanins and anthocyanin-rich extracts in cell culture models and in animal model tumor systems, and discuss their molecular mechanisms of action. We also suggest reasons for the apparent lack of correlation between the effectiveness of anthocyanins in laboratory model systems and in humans as evidenced by epidemiological studies. Future studies aimed at enhancing the absorption of anthocyanins and/or their metabolites are likely to be necessary for their ultimate use for chemoprevention of human cancer.

Apigenin: a promising molecule for cancer prevention

Apigenin, a naturally occurring plant flavone, abundantly present in common fruits and vegetables, is recognized as a bioactive flavonoid shown to possess anti-inflammatory, antioxidant and anticancer properties. Epidemiologic studies suggest that a diet rich in flavones is related to a decreased risk of certain cancers, particularly cancers of the breast, digestive tract, skin, prostate and certain hematological malignancies. It has been suggested that apigenin may be protective in other diseases that are affected by oxidative process, such as cardiovascular and neurological disorders, although more research needs to be conducted in this regard. Human clinical trials examining the effect of supplementation of apigenin on disease prevention have not been conducted, although there is considerable potential for apigenin to be developed as a cancer chemopreventive agent.

Repeat dose study of the cancer chemopreventive agent resveratrol in healthy volunteers: safety, pharmacokinetics, and effect on the insulin-like growth factor axis

Resveratrol, a naturally occurring polyphenol, has cancer chemopreventive properties in preclinical models. It has been shown to downregulate the levels of insulin-like growth factor-1 (IGF-I) in rodents. The purpose of the study was to assess its safety, pharmacokinetics, and effects on circulating levels of IGF-I and IGF-binding protein-3 (IGFBP-3) after repeated dosing. Forty healthy volunteers ingested resveratrol at 0.5, 1.0, 2.5, or 5.0 g daily for 29 days. Levels of resveratrol and its metabolites were measured by high performance liquid chromatography-UV in plasma obtained before and up to 24 hours after a dose between days 21 and 28. IGF-I and IGFBP-3 were measured by ELISA in plasma taken predosing and on day 29. Resveratrol was safe, but the 2.5 and 5 g doses caused mild to moderate gastrointestinal symptoms. Resveratrol-3-O-sulfate, resveratrol-4'-O-glucuronide, and resveratrol-3-O-glucuronide were major plasma metabolites. Maximal plasma levels and areas under the concentration versus time curve for the metabolites dramatically exceeded those for resveratrol, in the case of areas under the concentration versus time curve, by up to 20.3-fold. Compared with predosing values, the ingestion of resveratrol caused a decrease in circulating IGF-I and IGFBP-3 (P<0.04 for both), respectively, in all volunteers. The decrease was most marked at the 2.5 g dose level. The results suggest that repeated administration of high doses of resveratrol generates micromolar concentrations of parent and much higher levels of glucuronide and sulfate conjugates in the plasma. The observed decrease in circulating IGF-I and IGFBP-3 might contribute to cancer chemopreventive activity.

The Role of Resveratrol in Cancer Therapy

Natural product compounds have recently attracted significant attention from the scientific community for their potent effects against inflammation-driven diseases, including cancer. A significant amount of research, including preclinical, clinical, and epidemiological studies, has indicated that dietary consumption of polyphenols, found at high levels in cereals, pulses, vegetables, and fruits, may prevent the evolution of an array of diseases, including cancer. Cancer development is a carefully orchestrated progression where normal cells acquires mutations in their genetic makeup, which cause the cells to continuously grow, colonize, and metastasize to other organs such as the liver, lungs, colon, and brain. Compounds that modulate these oncogenic processes can be considered as potential anti-cancer agents that may ultimately make it to clinical application. Resveratrol, a natural stilbene and a non-flavonoid polyphenol, is a phytoestrogen that possesses anti-oxidant, anti-inflammatory, cardioprotective, and anti-cancer properties. It has been reported that resveratrol can reverse multidrug resistance in cancer cells, and, when used in combination with clinically used drugs, it can sensitize cancer cells to standard chemotherapeutic agents. Several novel analogs of resveratrol have been developed with improved anti-cancer activity, bioavailability, and pharmacokinetic profile. The current focus of this review is resveratrol’s in vivo and in vitro effects in a variety of cancers, and intracellular molecular targets modulated by this polyphenol. This is also accompanied by a comprehensive update of the various clinical trials that have demonstrated it to be a promising therapeutic and chemopreventive agent.

Natural Products as a Vital Source for the Discovery of Cancer Chemotherapeutic and Chemopreventive Agents

Throughout history, natural products have played a dominant role in the treatment of human ailments. For example, the legendary discovery of penicillin transformed global existence. Presently, natural products comprise a large portion of current-day pharmaceutical agents, most notably in the area of cancer therapy. Examples include Taxol, vinblastine, and camptothecin. These structurally unique agents function by novel mechanisms of action; isolation from natural sources is the only plausible method that could have led to their discovery. In addition to terrestrial plants as sources for starting materials, the marine environment (e.g., ecteinascidin 743, halichondrin B, and dolastatins), microbes (e.g., bleomycin, doxorubicin, and staurosporin), and slime molds (e.g., epothilone B) have yielded remarkable cancer chemotherapeutic agents. Irrespective of these advances, cancer remains a leading cause of death worldwide. Undoubtedly, the prevention of human cancer is highly preferable to treatment. Cancer chemoprevention, the use of vaccines or pharmaceutical agents to inhibit, retard, or reverse the process of carcinogenesis, is another important approach for easing this formidable public health burden. Similar to cancer chemotherapeutic agents, natural products play an important role in this field. There are many examples, including dietary phytochemicals such as sulforaphane and phenethyl isothiocyanate (cruciferous vegetables) and resveratrol (grapes and grape products). Overall, natural product research is a powerful approach for discovering biologically active compounds with unique structures and mechanisms of action. Given the unfathomable diversity of nature, it is reasonable to suggest that chemical leads can be generated that are capable of interacting with most or possibly all therapeutic targets.

Aflatoxin: a 50-year odyssey of mechanistic and translational toxicology

Since their discovery 50 years ago, the aflatoxins have become recognized as ubiquitous contaminants of the human food supply throughout the economically developing world. The adverse toxicological consequences of these compounds in populations are quite varied because of a wide range of exposures leading to acute effects, including rapid death, and chronic outcomes such as hepatocellular carcinoma. Furthermore, emerging studies describe a variety of general adverse health effects associated with aflatoxin, such as impaired growth in children. Aflatoxin exposures have also been demonstrated to multiplicatively increase the risk of liver cancer in people chronically infected with hepatitis B virus (HBV) illustrating the deleterious impact that even low toxin levels in the diet can pose for human health. The public health impact of aflatoxin exposure is pervasive. Aflatoxin biomarkers of internal and biologically effective doses have been integral to the establishment of the etiologic role of this toxin in human disease through better estimates of exposure, expanded knowledge of the mechanisms of disease pathogenesis, and as tools for implementing and evaluating preventive interventions.

Multi-targeted therapy of cancer by genistein

Soy isoflavones have been identified as dietary components having an important role in reducing the incidence of breast and prostate cancers in Asian countries. Genistein, the predominant isoflavone found in soy products, has been shown to inhibit the carcinogenesis in animal models. There is a growing body of experimental evidence showing that the inhibition of human cancer cell growth by genistein is mediated via the modulation of genes that are related to the control of cell cycle and apoptosis. It has been shown that genistein inhibits the activation of NF-kappaB and Akt signaling pathways, both of which are known to maintain a homeostatic balance between cell survival and apoptosis. Moreover, genistein antagonizes estrogen- and androgen-mediated signaling pathways in the processes of carcinogenesis. Furthermore, genistein has been found to have antioxidant properties, and shown to be a potent inhibitor of angiogenesis and metastasis. Taken together, both in vivo and in vitro studies have clearly shown that genistein, one of the major soy isoflavones is a promising agent for cancer chemoprevention and further suggest that it could be an adjunct to cancer therapy by virtue of its effects on reversing radioresistance and chemoresistance. In this review, we attempt to provide evidence for these preventive and therapeutic effects of genistein in a succinct manner highlighting comprehensive state-of-the-art knowledge regarding its multi-targeted biological and molecular effects in cancer cells.

Kaempferol: A Key Emphasis to Its Anticancer Potential

A marked decrease in human cancers, including breast cancer, bone cancer, and cervical cancer, has been linked to the consumption of vegetable and fruit, and the corresponding chemoprotective effect has been associated with the presence of several active molecules, such as kaempferol. Kaempferol is a major flavonoid aglycone found in many natural products, such as beans, bee pollen, broccoli, cabbage, capers, cauliflower, chia seeds, chives, cumin, moringa leaves, endive, fennel, and garlic. Kaempferol displays several pharmacological properties, among them antimicrobial, anti-inflammatory, antioxidant, antitumor, cardioprotective, neuroprotective, and antidiabetic activities, and is being applied in cancer chemotherapy. Specifically, kaempferol-rich food has been linked to a decrease in the risk of developing some types of cancers, including skin, liver, and colon. The mechanisms of action include apoptosis, cell cycle arrest at the G2/M phase, downregulation of epithelial-mesenchymal transition (EMT)-related markers, and phosphoinositide 3-kinase/protein kinase B signaling pathways. In this sense, this article reviews data from experimental studies that investigated the links between kaempferol and kaempferol-rich food intake and cancer prevention. Even though growing evidence supports the use of kaempferol for cancer prevention, further preclinical and clinical investigations using kaempferol or kaempferol-rich foods are of pivotal importance before any public health recommendation or formulation using kaempferol.

The chemistry and biology of nitroxide compounds

Cyclic nitroxides are a diverse group range of stable free radicals that have unique antioxidant properties. Because of their ability to interact with free radicals, they have been used for many years as biophysical tools. During the past 15-20 years, however, many interesting biochemical interactions have been discovered and harnessed for therapeutic applications. Biologically relevant effects of nitroxides have been described, including their ability to degrade superoxide and peroxide, inhibit Fenton reactions, and undergo radical-radical recombination. Cellular studies defined the activity of nitroxides in vitro. By modifying oxidative stress and altering the redox status of tissues, nitroxides have been found to interact with and alter many metabolic processes. These interactions can be exploited for therapeutic and research use, including protection against ionizing radiation, as probes in functional magnetic resonance imaging, cancer prevention and treatment, control of hypertension and weight, and protection from damage resulting from ischemia/reperfusion injury. Although much remains to be done, many applications have been well studied and some are currently being tested in clinical trials. The therapeutic and research uses of nitroxide compounds are reviewed here with a focus on the progress from initial development to modern trials.

Pharmacokinetics of curcumin conjugate metabolites in healthy human subjects

BACKGROUND

Curcumin is a polyphenol, found in the spice turmeric, that has promising anticancer properties, but previous studies suggest that absorption of curcumin may be limited.

METHODS

This study examined the pharmacokinetics of a curcumin preparation in healthy human volunteers 0.25 to 72 h after a single oral dose. Curcumin was administered at doses of 10 g (n = 6) and 12 g (n = 6). Subjects were randomly allocated to dose level for a total of six subjects at each dose level. Serum samples were assayed for free curcumin, for its glucuronide, and for its sulfate conjugate. The data were fit to a one-compartment absorption and elimination model.

RESULTS

Using a high-performance liquid chromatography assay with a limit of detection of 50 ng/mL, only one subject had detectable free curcumin at any of the 14 time points assayed, but curcumin glucuronides and sulfates were detected in all subjects. Based on the pharmacokinetic model, the area under the curve for the 10 and 12 g doses was estimated (mean +/- SE) to be 35.33 +/- 3.78 and 26.57 +/- 2.97 mug/mL x h, respectively, whereas C(max) was 2.30 +/- 0.26 and 1.73 +/- 0.19 mug/mL. The T(max) and t(1/2) were estimated to be 3.29 +/- 0.43 and 6.77 +/- 0.83 h. The ratio of glucuronide to sulfate was 1.92:1. The curcumin conjugates were present as either glucuronide or sulfate, not mixed conjugates.

CONCLUSION

Curcumin is absorbed after oral dosing in humans and can be detected as glucuronide and sulfate conjugates in plasma.

Multi-targeted prevention of cancer by sulforaphane

Isothiocyanates are found in cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower, and cabbage. Epidemiologic studies suggest that cruciferous vegetable intake may lower overall cancer risk, including colon and prostate cancer. Sulforaphane (SFN) is an isothiocyanate found in cruciferous vegetables and is especially high in broccoli and broccoli sprouts. SFN has proved to be an effective chemoprotective agent in cell culture, carcinogen-induced and genetic animal cancer models, as well as in xenograft models of cancer. Early research focused on the "blocking activity" of SFN via Phase 2 enzyme induction, as well as inhibition of enzymes involved in carcinogen activation, but there has been growing interest in other mechanisms of chemoprotection by SFN. Recent studies suggest that SFN offers protection against tumor development during the "post-initiation" phase and mechanisms for suppression effects of SFN, including cell cycle arrest and apoptosis induction are of particular interest. In humans, a key factor in determining the efficacy of SFN as a chemoprevention agent is gaining an understanding of the metabolism, distribution and bioavailability of SFN and the factors that alter these parameters. This review discusses the established anti-cancer properties of SFN, with an emphasis on the possible chemoprevention mechanisms. The current status of SFN in human clinical trials also is included, with consideration of the chemistry, metabolism, absorption and factors influencing SFN bioavailability.

Inhibition of prostate carcinogenesis in TRAMP mice by oral infusion of green tea polyphenols

Development of effective chemopreventive agents against prostate cancer (CaP) for humans requires conclusive evidence of their efficacy in animal models that closely emulates human disease. The autochthonous transgenic adenocarcinoma of the mouse prostate (TRAMP) model, which spontaneously develops metastatic CaP, is one such model that mimics progressive forms of human disease. Employing male TRAMP mice, we show that oral infusion of a polyphenolic fraction isolated from green tea (GTP) at a human achievable dose (equivalent to six cups of green tea per day) significantly inhibits CaP development and increases survival in these mice. In two separate experiments, the cumulative incidence of palpable tumors at 32 weeks of age in 20 untreated mice was 100% (20 of 20). In these mice, 95% (19 of 20), 65% (13 of 20), 40% (8 of 20), and 25% (5 of 20) of the animals exhibited distant site metastases to lymph nodes, lungs, liver, and bone, respectively. However, 0.1% GTP (wt/vol) provided as the sole source of drinking fluid to TRAMP mice from 8 to 32 weeks of age resulted in (i) significant delay in primary tumor incidence and tumor burden as assessed sequentially by MRI, (ii) significant decrease in prostate (64%) and genitourinary (GU) (72%) weight, (iii) significant inhibition in serum insulin-like growth factor-I and restoration of insulin-like growth factor binding protein-3 levels, and (iv) marked reduction in the protein expression of proliferating cell nuclear antigen (PCNA) in the prostate compared with water-fed TRAMP mice. The striking observation of this study was that GTP infusion resulted in almost complete inhibition of distant site metastases. Furthermore, GTP consumption caused significant apoptosis of CaP cells, which possibly resulted in reduced dissemination of cancer cells, thereby causing inhibition of prostate cancer development, progression, and metastasis of CaP to distant organ sites.

Metformin prevents tobacco carcinogen--induced lung tumorigenesis

Activation of the mammalian target of rapamycin (mTOR) pathway is an important and early event in tobacco carcinogen-induced lung tumorigenesis, and therapies that target mTOR could be effective in the prevention or treatment of lung cancer. The biguanide metformin, which is widely prescribed for the treatment of type II diabetes, might be a good candidate for lung cancer chemoprevention because it activates AMP-activated protein kinase (AMPK), which can inhibit the mTOR pathway. To test this, A/J mice were treated with oral metformin after exposure to the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Metformin reduced lung tumor burden by up to 53% at steady-state plasma concentrations that are achievable in humans. mTOR was inhibited in lung tumors but only modestly. To test whether intraperitoneal administration of metformin might improve mTOR inhibition, we injected mice and assessed biomarkers in liver and lung tissues. Plasma levels of metformin were significantly higher after injection than oral administration. In liver tissue, metformin activated AMPK and inhibited mTOR. In lung tissue, metformin did not activate AMPK but inhibited phosphorylation of insulin-like growth factor-I receptor/insulin receptor (IGF-1R/IR), Akt, extracellular signal-regulated kinase (ERK), and mTOR. This suggested that metformin indirectly inhibited mTOR in lung tissue by decreasing activation of insulin-like growth factor-I receptor/insulin receptor and Akt upstream of mTOR. Based on these data, we repeated the NNK-induced lung tumorigenesis study using intraperitoneal administration of metformin. Metformin decreased tumor burden by 72%, which correlated with decreased cellular proliferation and marked inhibition of mTOR in tumors. These studies show that metformin prevents tobacco carcinogen-induced lung tumorigenesis and support clinical testing of metformin as a chemopreventive agent.

Aspirin inhibits mTOR signaling, activates AMP-activated protein kinase, and induces autophagy in colorectal cancer cells

BACKGROUND & AIMS

Aspirin reduces the incidence of and mortality from colorectal cancer (CRC) by unknown mechanisms. Cancer cells have defects in signaling via the mechanistic target of rapamycin (mTOR), which regulates proliferation. We investigated whether aspirin affects adenosine monophosphate-activated protein kinase (AMPK) and mTOR signaling in CRC cells.

METHODS

The effects of aspirin on mTOR signaling, the ribosomal protein S6, S6 kinase 1 (S6K1), and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) were examined in CRC cells by immunoblotting. Phosphorylation of AMPK was measured; the effects of loss of AMPKα on the aspirin-induced effects of mTOR were determined using small interfering RNA (siRNA) in CRC cells and in AMPK(α1/α2-/-) mouse embryonic fibroblasts. LC3 and ULK1 were used as markers of autophagy. We analyzed rectal mucosa samples from patients given 600 mg aspirin, once daily for 1 week.

RESULTS

Aspirin reduced mTOR signaling in CRC cells by inhibiting the mTOR effectors S6K1 and 4E-BP1. Aspirin changed nucleotide ratios and activated AMPK in CRC cells. mTOR was still inhibited by aspirin in CRC cells after siRNA knockdown of AMPKα, indicating AMPK-dependent and AMPK-independent mechanisms of aspirin-induced inhibition of mTOR. Aspirin induced autophagy, a feature of mTOR inhibition. Aspirin and metformin (an activator of AMPK) increased inhibition of mTOR and Akt, as well as autophagy in CRC cells. Rectal mucosal samples from patients given aspirin had reduced phosphorylation of S6K1 and S6.

CONCLUSIONS

Aspirin is an inhibitor of mTOR and an activator of AMPK, targeting regulators of intracellular energy homeostasis and metabolism. These could contribute to its protective effects against development of CRC.

Risk for colorectal cancer in ulcerative colitis: changes, causes and management strategies

The risk of colorectal cancer for any patient with ulcerative colitis is known to be elevated, and is estimated to be 2% after 10 years, 8% after 20 years and 18% after 30 years of disease. Risk factors for cancer include extent and duration of ulcerative colitis, primary sclerosing cholangitis, a family history of sporadic colorectal cancer, severity of histologic bowel inflammation, and in some studies, young age at onset of colitis. In this review, the authors discuss recent epidemiological trends and causes for the observed changes. Population-based studies published within the past 5 years suggest that this risk has decreased over time, despite the low frequency of colectomies. The crude annual incidence rate of colorectal cancer in ulcerative colitis ranges from approximately 0.06% to 0.16% with a relative risk of 1.0-2.75. The exact mechanism for this change is unknown; it may partly be explained by the more widespread use of maintenance therapy and surveillance colonoscopy.

Plants vs. cancer: a review on natural phytochemicals in preventing and treating cancers and their druggability

Cancer remains to be one of the leading causes of death in the United States and around the world. The advent of modern drug-targeted therapies has undeniably improved cancer patients' cares. However, advanced metastasized cancer remains untreatable. Hence, continued searching for a safer and more effective chemoprevention and treatment is clearly needed for the improvement of the efficiency and to lower the treatment cost for cancer care. Cancer chemoprevention with natural phytochemical compounds is an emerging strategy to prevent, impede, delay, or cure cancer. This review summarizes the latest research in cancer chemoprevention and treatment using the bioactive components from natural plants. Relevant molecular mechanisms involved in the pharmacological effects of these phytochemicals are discussed. Pharmaceutical developmental challenges and opportunities in bringing the phytochemicals into the market are also explored. The authors wish to expand this research area not only for their scientific soundness, but also for their potential druggability.

Contribution to Tumor Angiogenesis From Innate Immune Cells Within the Tumor Microenvironment: Implications for Immunotherapy

The critical role of angiogenesis in promoting tumor growth and metastasis is strongly established. However, tumors show considerable variation in angiogenic characteristics and in their sensitivity to antiangiogenic therapy. Tumor angiogenesis involves not only cancer cells but also various tumor-associated leukocytes (TALs) and stromal cells. TALs produce chemokines, cytokines, proteases, structural proteins, and microvescicles. Vascular endothelial growth factor (VEGF) and inflammatory chemokines are not only major proangiogenic factors but are also immune modulators, which increase angiogenesis and lead to immune suppression. In our review, we discuss the regulation of angiogenesis by innate immune cells in the tumor microenvironment, specific features, and roles of major players: macrophages, neutrophils, myeloid-derived suppressor and dendritic cells, mast cells, γδT cells, innate lymphoid cells, and natural killer cells. Anti-VEGF or anti-inflammatory drugs could balance an immunosuppressive microenvironment to an immune permissive one. Anti-VEGF as well as anti-inflammatory drugs could therefore represent partners for combinations with immune checkpoint inhibitors, enhancing the effects of immune therapy.

Protection against beta-amyloid peptide toxicity in vivo with long-term administration of ferulic acid

1. beta-Amyloid peptide (A beta), a 39 -- 43 amino acid peptide, is believed to induce oxidative stress and inflammation in the brain, which are postulated to play important roles in the pathogenesis of Alzheimer's disease. Ferulic acid is an antioxidant and anti-inflammatory agent derived from plants; therefore, the potential protective activity of ferulic acid against A beta toxicity in vivo was examined. 2. Mice were allowed free access to drinking water (control) or water containing ferulic acid (0.006%). After 4 weeks, A beta 1-42 (410 pmol) was administered via intracerebroventricular injection. 3. Injection of control mice with A beta 1-42 impaired performance on the passive avoidance test (35% decrease in step-through latency), the Y-maze test (19% decrease in alternation behaviour), and the water maze test (32% decrease in percentage time in platform-quadrant). In contrast, mice treated with ferulic acid prior to A beta 1-42 administration were protected from these changes (9% decrease in step-through latency; no decrease in alternation behaviour; 14% decrease in percentage time in platform-quadrant). A beta 1-42 induced 31% decrease in acetylcholine level in the cortex, which was tended to be ameliorated by ferulic acid. 4. In addition, A beta 1-42 increased immunoreactivities of the astrocyte marker glial fibrillary acidic protein (GFAP) and interleukin-1 beta (IL-1 beta) in the hippocampus, effects also suppressed by pretreatment with ferulic acid. 5. Administration of ferulic acid per se unexpectedly induced a transient and slight increase in GFAP and IL-1 beta immunoreactivity in the hippocampus on day 14, which returned to basal levels on day 28. A slight (8%) decrease in alternation behaviour was observed on day 14. 6. These results demonstrate that long-term administration of ferulic acid induces resistance to A beta 1-42 toxicity in the brain, and suggest that ferulic acid may be a useful chemopreventive agent against Alzheimer's disease.

The benefit of mass eradication of Helicobacter pylori infection: a community-based study of gastric cancer prevention

OBJECTIVE

To evaluate the benefit of mass eradication of Helicobacter pylori infection in reducing premalignant gastric lesions.

DESIGN

Mass eradication of H pylori infection was started from 2004 for a Taiwanese population with prevalent H pylori infection, who were >30 years of age. Participants positive for the (13)C-urea breath test underwent endoscopic screening and 1-week clarithromycin-based triple therapy. For subjects whose initial treatment failed, 10-day levofloxacin-based triple therapy was administered. The main outcome measures were changes in the prevalence of H pylori infection and premalignant gastric lesions, and changes in the incidence of premalignant gastric lesions and gastric cancer before (1995-2003) and after (2004-2008) chemoprevention using various comparators.

RESULTS

The reduction in H pylori infection was 78.7% (95% CI 76.8% to 80.7%), and the estimated incidence of re-infection/recrudescence was 1% (95% CI 0.6% to 1.4%) per person-year. The effectiveness of reducing the incidence of gastric atrophy resulting from chemoprevention was significant at 77.2% (95% CI 72.3% to 81.2%), while the reduction in intestinal metaplasia was not significant. Compared with the 5-year period before chemoprevention and in the absence of endoscopic screening, the effectiveness in reducing gastric cancer incidence during the chemoprevention period was 25% (rate ratio 0.753, 95% CI 0.372 to 1.524). The reduction in peptic ulcer disease was 67.4% (95% CI 52.2% to 77.8%), while the incidence of oesophagitis was 6% (95% CI 5.1% to 6.9%) after treatment.

CONCLUSIONS

Population-based eradication of H pylori infection has led to a significant reduction in gastric atrophy at the expense of increased oesophagitis. The ultimate benefit in reducing gastric cancer incidence and its mortality should be validated by a further long-term follow-up.

Multitargeted therapy of cancer by silymarin

Silymarin, a flavonolignan from milk thistle (Silybum marianum) plant, is used for the protection against various liver conditions in both clinical settings and experimental models. In this review, we summarize the recent investigations and mechanistic studies regarding possible molecular targets of silymarin for cancer prevention. Number of studies has established the cancer chemopreventive role of silymarin in both in vivo and in vitro models. Silymarin modulates imbalance between cell survival and apoptosis through interference with the expressions of cell cycle regulators and proteins involved in apoptosis. In addition, silymarin also showed anti-inflammatory as well as anti-metastatic activity. Further, the protective effects of silymarin and its major active constituent, silibinin, studied in various tissues, suggest a clinical application in cancer patients as an adjunct to established therapies, to prevent or reduce chemotherapy as well as radiotherapy-induced toxicity. This review focuses on the chemistry and analogues of silymarin, multiple possible molecular mechanisms, in vitro as well as in vivo anti-cancer activities, and studies on human clinical trials.

The cancer preventative agent resveratrol is converted to the anticancer agent piceatannol by the cytochrome P450 enzyme CYP1B1

Resveratrol is a cancer preventative agent that is found in red wine. Piceatannol is a closely related stilbene that has antileukaemic activity and is also a tyrosine kinase inhibitor. Piceatannol differs from resveratrol by having an additional aromatic hydroxy group. The enzyme CYP1B1 is overexpressed in a wide variety of human tumours and catalyses aromatic hydroxylation reactions. We report here that the cancer preventative agent resveratrol undergoes metabolism by the cytochrome P450 enzyme CYP1B1 to give a metabolite which has been identified as the known antileukaemic agent piceatannol. The metabolite was identified by high performance liquid chromatography analysis using fluorescence detection and the identity of the metabolite was further confirmed by derivatisation followed by gas chromatography-mass spectrometry studies using authentic piceatannol for comparison. This observation provides a novel explanation for the cancer preventative properties of resveratrol. It demonstrates that a natural dietary cancer preventative agent can be converted to a compound with known anticancer activity by an enzyme that is found in human tumours. Importantly this result gives insight into the functional role of CYP1B1 and provides evidence for the concept that CYP1B1 in tumours may be functioning as a growth suppressor enzyme.

PGAM5 tethers a ternary complex containing Keap1 and Nrf2 to mitochondria

Eukaryote cells balance production of reactive oxygen species (ROS) with levels of anti-oxidant enzyme activity to maintain cellular redox homeostasis. Mitochondria are a major source of ROS, while many anti-oxidant genes are regulated by the Nrf2 transcription factor. Keap1, a redox-regulated substrate adaptor for a cullin-based ubiquitin ligase, targets Nrf2 for proteosome-mediated degradation and represses Nrf2-dependent gene expression. We have previously identified a member of the phosphoglycerate mutase family, PGAM5, as a Keap1-binding protein. In this report, we demonstrate that PGAM5 is targeted to the outer membrane of mitochondria by an N-terminal mitochondrial-localization sequence. Furthermore, we provide evidence that PGAM5 forms a ternary complex containing both Keap1 and Nrf2, in which the dimeric Keap1 protein simultaneously binds both PGAM5 and Nrf2 through their conserved E(S/T)GE motifs. Knockdown of either Keap1 or PGAM5 activates Nrf2-dependent gene expression. We suggest that this ternary complex provides a molecular framework for understanding how nuclear anti-oxidant gene expression is regulated in response to changes in mitochondrial function(s).