Role of natural products in breast cancer related symptomology: Targeting chronic inflammation

Breast cancer is the most common cancer in women worldwide. There have been many advancements in the treatment of breast cancer leading to an increased population of patients living with this disease. Accumulating evidence suggests that cancer diagnosis and aftermath experienced stress could not only affect the quality of life of cancer patients, but it could also influence their disease outcome. The magnitude of stress experienced by breast cancer patients is often compared to the post-traumatic stress disorder-like symptoms suggested to be mediated by the chronic inflammation including NF-κB, AKt, p53 and other inflammatory pathways. Here, we describe the symptomology of PTSD-like symptoms in breast cancer patients and argue that they may in fact be caused by or maintained through aspects of chronic inflammation mediated by the pro-inflammatory markers. Evidence exists that natural products that might attenuate or lessen the effects of chronic inflammation abound in the diet. We summarize some possible agents that might abate the genesis of symptoms experienced by breast cancer patients while mitigating the effect of inflammation.

The Highly Pure Neem Leaf Extract, SCNE, Inhibits Tumorigenesis in Oral Squamous Cell Carcinoma via Disruption of Pro-tumor Inflammatory Cytokines and Cell Signaling

Oral squamous cell carcinoma (OSCC) is a deadly disease that comprises 60% of all head and neck squamous cell cancers. The leaves of the Neem tree (Azadirachta indica) have been used in traditional Ayurvedic medicine for centuries to treat numerous oral maladies and are known to have significant anti-inflammatory properties. We hypothesize that a highly pure super critical CO₂ Neem leaf extract (SCNE) prevents initiation and progression of OSCC via downregulation of intra-tumor pro-inflammatory pathways, which promote tumorigenesis. Hence, we investigated the anticancer effects of SCNE using in vitro and in vivo platforms. OSCC cell lines (SCC4, Cal27, and HSC3) were treated with SCNE while inflammation, proliferation, and migration were analyzed over time. SCNE treatment significantly inhibited OSCC cell proliferation and migration and reduced MMP activity in vitro, suggesting its potential to inhibit tumor growth and metastasis. The preventive effects of SCNE in ectopic xenograft and 4NQO-1 (4-Nitroquinoline-1-oxide) carcinogen-induced mouse models of OSCC were also evaluated. Indeed, xenografted nude mice showed significant reduction of OSCC tumor volumes. Likewise, SCNE significantly reduced the incidence of tongue dysplasia in the 4NQO-1 OSCC initiation model. In both OSCC animal models, SCNE significantly depressed circulating pro-cancer inflammatory cytokines (host and tumor-secreted) including NFkB, COX2, IL-1, IL-6, TNFα, and IFNγ. In addition, we demonstrate that SCNE downregulates STAT3 and AKT expression and activity in vitro. We also demonstrate that the primary active component, nimbolide (NIM), has significant anticancer activity in established OSCC xenografts. Lastly, we show that SCNE induces an M1 phenotype in tumor associated macrophages (TAMS) in vivo. Taken together, these data strongly support SCNE as means of preventing OSCC via downregulation of pro-cancer inflammatory cascades and NIM as a potential new therapy for existing OSCC.

Abstract 3020: Natural & synthetic glucocorticoids induce therapy resistance in breast cancer in vitro

BACKGROUND: Research indicates that chronic psychological stress, mediated by the excessive release of glucocorticoid (GC) cortisol, may play a role in cancer progression and patient survival. Thus, synthetic GCs, such as dexamethasone, are widely used in conjugation with cancer therapy due to their ability to induce apoptosis. Surprisingly, recent evidence suggest that GCs can induce therapy-resistance in solid tumors, although the precise mechanisms are not well defined. Therefore, there is an urgent need for both clinical and detailed mechanistic studies elucidating the role of GCs in cancer treatment. The goal of this study was to investigate the role of natural and synthetic GCs on resistance to cytotoxic therapy in breast cancer in vitro.

METHODS: We either pre-treated or co-treated human breast cancer cells (MCF7, MDA-MB-231) with physiological and therapeutic doses of cortisol and dexamethasone (0.1-10 µM) alone or in combination with chemotherapy drug Fluorouracil (5FU) for 48-96 hours. We performed cell viability, proliferation, cell cycle and apoptosis assays. Thus, we used the glucocorticoid receptor (GR) antagonist (RU-486) to assess the role of GC receptor signaling. The expression of GR was confirmed by western blots.

RESULTS: Our results indicate that GCs alone or in combination with 5FU enhanced cell proliferation, especially in MDA-MB-231 cells (p<0.01). Furthermore, GCs also modulated cell cycle and apoptosis. Finally, RU-486, which antagonizes the action of GR, restored the apoptosis sensitivity of the GCs treated cells.

CONCLUSIONS: Our study suggests that in contrast to the pro-apoptotic effect of GCs in lymphoid cells, co-treatment of GCs protected breast cancer cells from 5FU-induced apoptosis. Given our results, it is difficult to conclude whether the primary detrimental effect of GCs is on cell viability and apoptosis. We cannot rule out the possibility that GCs my enhance resistance to chemotherapeutic drugs by modifying inflammation, angiogenesis or cell migration. Therefore, our current studies are aimed at investigating the possible pathways mediating GCs induced resistance to therapy in vitro. Our ultimate goal is to elucidate the molecular mechanisms of the glucocorticoids mediated inhibition of chemotherapy-induced cell death thereby proposing the ways of reversing this process. The literature suggest that around 35-45 % of cancer patients experience significant level of stress which manifests in elevated production of natural GC cortisol. Furthermore, given that GCs are widely accepted as an adjuvant treatment during chemotherapy or radiotherapy for reducing side effects, it is critical to investigate the conditions upon which they exert either pro-apoptotic or anti-apoptotic action in different cancer types. Although more data is needed, our findings imply careful consideration for the profligate use of GCs combination therapy in the treatment of cancer patients.

Citation Format: Kristina Andrijauskaite, Michael J. Wargovich. Natural & synthetic glucocorticoids induce therapy resistance in breast cancer in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3020.

Reduction in promotor methylation utilizing EGCG (epigallocatechin-3-gallate) restores RXRα expression in human colon cancer cells

Silencing of regulatory genes through hypermethylation of CpG islands is an important mechanism in tumorigenesis. In colon cancer, RXRα, an important dimerization partner with other nuclear transcription factors, is silenced through this mechanism. We previously found that colon tumors in Apc^Min/+ mice had diminished levels of RXRα protein and expression levels of this gene were restored by treatment with a green tea intervention, due to reduced promoter methylation of RXRα. We hypothesized that CIMP+ cell lines, which epigenetically silence key regulatory genes would also evidence silencing of RXRα and EGCG treatment would restore its expression. We indeed found EGCG to restore RXRα activity levels in the human cell lines, in a dose dependent manner and reduced RXRα promoter methylation. EGCG induced methylation changes in several other colon cancer related genes but did not cause a decrease in global methylation. Numerous epidemiological reports have shown the benefits of green tea consumption in reducing colon cancer risk but to date no studies have shown that the risk reduction may be related to the epigenetic restoration by tea polyphenols. Our results show that EGCG modulates the reversal of gene silencing involved in colon carcinogenesis providing a possible avenue for colon cancer prevention and treatment.

Abstract B06: Trajectories of inflammatory biomarkers: A randomized longitudinal 12-months intervention promoting anti-inflammatory food consumption among breast cancer survivors

U.S. breast cancer survivors (BCSs) are expected to increase to 4 million in the next 5-10 years. Cancer recurrence risk is highest in obese survivors. Inflammatory (Pro-I) biomarkers including C-reactive protein (CRP), Interleukins -3, -6, and -8 (IL-3, IL-6, IL-8), and Tumor Necrosis Factor (TNF)-α have been associated with cancer severity and recurrence. Nutritional interventions aimed at reducing inflammation may contribute to reduced recurrence risk and increase survival rates. However, studies have been limited to animal models. The goals of this one-year culinary-based intervention were to: 1) decrease Pro-I biomarkers and increase anti-inflammatory (AI) cytokines like IL10, by promoting AI food incorporation into BCS dietary routines; and 2) examine effects on potential cancer risk factors including body mass index (BMI) and circulating adipose stromal cells (ASCs).

A total of 153 BCSs was recruited. Overweight and obese women aged 18 or older, diagnosed with Stage 0-III breast cancer and at least 2 months post-systemic therapy at time of enrollment were randomized into Intervention (IG; n=76) and Control (CG; n=77) groups. CG received monthly nutritional brochures from the American Institute for Cancer Research. IG attended 6 monthly workshops (brief lectures on AI topics and chef-prepared food demonstrations), and received monthly tailored newsletters and telephone calls incorporating Motivational Interviewing techniques. At baseline, 6- and 12-month assessments, fasting serum was collected and assayed for Pro-I/AI marker and ASC levels; BMI was calculated from measured height and weight.

We examined trajectories of inflammatory biomarkers and whether these are affected by intervention group assignment and potential confounders. For each biomarker, we identified groups of trajectories from baseline to 12 months by modeling log-transformed longitudinal data using a discrete mixture model with censored normal distribution. Model fit diagnostics based on Bayesian information criterion, classification measures, and clinical judgement were used to determine the number of groups. Then, we investigated the association between trajectory group classification and covariates using chi-square test for categorical variables and ANOVA for continuous variables.

Participants' mean age at baseline was 56.6 (SD=9.4); mean BMI 32.4 kg/m2 (SD=4.9). There were no significant differences between groups on demographic variables. Intervention resulted in small changes in expected direction for CRP and IL-6 markers overall at 6 and 12 months, and for IL-8 only at 6 months. Between two and five trajectory patterns (linear or quadratic) were identified across all biomarkers. These patterns suggest that distinct BCS subpopulations that benefit differentially from nutritional interventions exist; therefore, suggesting tailoring strategies for future interventions. Future studies in larger samples are needed to provide more robust parameter estimation and facilitate generalizability of results.

Citation Format: Amelie G. Ramirez, Edgar Munoz, Dorothy Long-Parma, Alan EC Holden, Michael J. Wargovich. Trajectories of inflammatory biomarkers: A randomized longitudinal 12-months intervention promoting anti-inflammatory food consumption among breast cancer survivors. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr B06.

Chemoprevention in gastrointestinal physiology and disease. Targeting the progression of cancer with natural products: a focus on gastrointestinal cancer

The last decade has witnessed remarkable progress in the utilization of natural products for the prevention and treatment of human cancer. Many agents now in the pipeline for clinical trial testing have evolved from our understanding of how human nutritional patterns account for widespread differences in cancer risk. In this review, we have focused on many of these promising agents arguing that they may provide a new strategy for cancer control: natural products once thought to be only preventive in their mode of action now are being explored for efficacy in tandem with cancer therapeutics. Natural products may reduce off-target toxicity of therapeutics while making cancers more amenable to therapy. On the horizon is the use of certain natural products, in their own right, as mitigants of late-stage cancer, a new frontier for small-molecule natural product drug discovery.

Abstract A66: An anti-inflammatory dietary intervention to reduce breast cancer recurrence risk: Preliminary data from a pilot study

Background: U.S. breast cancer survivors (BCSs) are expected to increase from 3 to 4 million in the next 5-10 years. Cancer recurrence risk is highest in obese survivors. Pro-inflammatory biomarkers including C-reactive protein (CRP), Interleukins -3, -6, and -8 (IL-3, IL-6, IL-8), and Tumor Necrosis Factor (TNF)α have been associated with cancer severity and recurrence. Nutritional interventions aimed at reducing inflammation (INF) may contribute to reduced recurrence risk and potentially increase survival rates. However, studies to date have been conducted predominantly in animal models. The primary goal of this one-year culinary-based pilot intervention is to improve BCS biomarker profiles -- decrease pro-inflammatory biomarkers and increase anti-inflammatory (AI) cytokines like IL-10 -- by promoting incorporation of AI foods into dietary routines. The secondary goal is to examine effects on potential cancer risk factors including body mass index (BMI), stress and depression levels.

Methods: A total of 153 BCSs was recruited. Overweight and obese women aged 18 or older, diagnosed with Stage 0-III breast cancer who were at least 2 months post-systemic therapy at time of enrollment were randomized into Intervention (IG; n=76) and Control (CG; n=77) groups. The CG received monthly nutritional brochures from the American Institute for Cancer Research. IG participants attended 6 monthly workshops consisting of brief lectures on AI topics and chef-prepared food demonstrations, and received monthly tailored newsletters and follow-up telephone calls incorporating Motivational Interviewing techniques. At baseline and 6- and 12-month follow-up assessments, fasting blood samples were collected from all participants and assayed for inflammatory marker levels. BMI and waist circumference were measured, and self-reported data on dietary habits, demographics, physical activity (PA), perceived stress (PSS) and depression levels were collected. Violin plots of baseline, 6- and 12-month BMI were generated in R version 3.1.3 (R Core Team, 2013) for participants who had completed all three assessments (n=46). Path Analysis and Structural Equation Modeling were conducted using both R and Stata version 13 (Stata Corp, College Station, TX, 2014) to test hypothesized relationships among latent and observed variables.

Results: Participants were characterized at baseline by mean age of 56.6 ± 9.4 years and mean BMI of 32.4 ± 4.9 kg/m2. Women self-identified as U.S. Latino or Anglo (41.2% and 43.1%, respectively), had college-level education or bachelor's degree (65.4%), were employed full-time (51.6%) and privately insured (80.9%). There were no significant differences between groups. All Interleukins were significant predictors of INF (standardized coefficient βs>0.83, p<0.001). Although not significant, INF had positive relationships with BMI (βs=0.06) and PSS (βs=0.10), and negative relationships with PA (βs=-0.01) and AI diet (βs=-0.03). AI diet was negatively correlated with depression (r=-0.47). The IG plots (n=20) showed a progressive decrease in median BMI from baseline to 12 months (32.3, 31.6, 30.6, respectively; Interquartile ranges [IQR] 7.3, 6.2, 7.7). In contrast, the CG (n=26) demonstrated minimal change (median BMI=30.0, 30.7, 30.5, respectively; IQR=4.3, 5.2, 5.3).

Conclusion: Ongoing analyses will determine relationship significance over the entire study period. Future studies are needed in larger populations with increased INF-related morbidity and mortality risks, to provide more robust estimation of parameters and fit statistics and facilitate generalizability of results.

Citation Format: Amelie G. Ramirez, Edgar Muñoz, Dorothy Long-Parma, Kristin D. Mendoza, Alan E.C. Holden, Michael J. Wargovich. An anti-inflammatory dietary intervention to reduce breast cancer recurrence risk: Preliminary data from a pilot study. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr A66.

Natural Agents Used in Chemoprevention of Aerodigestive and GI Cancers

Aerodigestive cancers are on an increasing level in both occurrence and mortality. A major cause in many of these cancers is disruption of the inflammatory pathway, leading to increased cell proliferation, and epigenetic silencing of normal regulatory genes. Here we review the research on several natural products: silibinin, silymarin, quercetin, neem & nimbolide, gingerol, epigallatecatechin-3- gallate, curcumin, genistein and resveratrol conducted on aerodigestive cancers. These types of cancers are primarily those from oral cavity, esophagus/windpipe, stomach, small and large intestine, colon/rectum and bile/pancreas tissues. We report on the utilization in vivo and in vitro systems to research these dose effects on the inflammatory and epigenetic pathway components within the aerodigestive cancer. To follow up on the basic research we will discuss remaining research questions and future directions involving these natural products as putative stand alone or in combination with clinical agents.

Abstract CT122: RCT of an herbal mouthrinse for radiotherapy induced oral mucositis in cancer patients

Objectives: Primary aim of the ongoing study (NCT01898091) is to determine whether a mouthrinse containing extract of neem leaf (Azadirachta indica A. Juss.), a tropical evergreen tree with anti-inflammatory and anti-microbial medicinal properties, will lessen the severity of oral mucositis (OM) in patients undergoing radiation therapy (RT) to the head and neck. Secondary aims are to assess the effects of the neem mouthrinse on the microbial environment of the oral cavity and on quality of life.

Methods: Design is a double-blind, controlled, randomized, parallel-group Phase II clinical trial at a single NCI designated center. Block-randomization was used for patient assignment, stratified by tobacco use. Eligibles were adults with histologically confirmed head and neck cancer (HNC) whose treatment includes RT for 7 weeks. HNC includes malignancy of the oral cavity, oro-pharynx and larynx (ICD-9 codes 140 - 149, 161; ICD-O morphology code of 2 or 3). Exclusion criteria include prior HNC radiotherapy, baseline mouth and throat soreness (MTS) score of >3, ECOG performance status >2, allergy or inability to use mouthrinse, and language barrier. Evaluable participants receive > 40 Gy RT and participate to week 6 RT. Study duration is 12 weeks with visits at baseline, weekly during RT, 3 telephone visits post RT, and one-month follow-up visit. Data were collected using the Oral Mucositis Daily Questionnaire, Functional Assessment of Cancer Therapy-Head and Neck, and Symptom Distress Scale questionnaires; CariScreen for oral microbial load, and ELISA and flow cytometry for salivary analyte measures.

Results: Of 53 patients enrolled, 3 screen failed and 8 withdrew leaving 42 with evaluable data. Neem (n = 23) and placebo (n = 19) groups were not statistically different for demographic and clinical variables. Major hypothesis assessed as the maximum change in MTS score from baseline during 6 weeks of RT resulted in a larger change, 1.91 with SD 1.34 for neem group vs. 1.71 with SD 1.29 for placebo group based on a Wilcoxon rank sum test with one-sided alpha = 0.05. Preliminary results suggest no difference in the maximum change in severity from baseline (p = 0.85). Neem group had higher adherence to mouthrinse protocol measured as ≥4 days mouthrinse use per week for six weeks (OR 2.56, p = 0.19). Additional outcomes of ongoing comparisons across groups include time to maximum OM severity, time to onset of OM, percent of patients with MTS scores <3, and percent of patients by levels of change in MTS score. Regression analyses will be used to assess relationships between maximum and temporal changes in MTS score and mouthrinse group, adjusted for baseline characteristics and pertinent events. Relationships between changes in MTS score and mouthrinse usage over the time-course of the study will also be explored by graphical comparisons and regression approaches. Time to event outcomes will be assessed using Kaplan-Meier curves and comparisons will be made by log rank tests. Due to sample size, these latter analyses will be exploratory.

Citation Format: Susan G. Reed, Joan E. Cunningham, Elizabeth Garrett-Mayer, Jennifer L. Mulligan, Laura D. Fields, Lynsey R. Boyle, Sarah P. Daanen, John H. Keller, Casey L. Roach, Whitney C. Pasquini, Lauren Lawrence, Howell Harmon, Ahmad R. Garrett, Michael J. Wargovich, Anand K. Sharma. RCT of an herbal mouthrinse for radiotherapy induced oral mucositis in cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT122. doi:10.1158/1538-7445.AM2015-CT122

Abstract 410: Epigallocatechin gallate inhibits colon cancer cell proliferation by modulating epigenetic enzymes (DNMTs, HDACs, and HATs)

Epigallocatechin gallate (EGCG), a major constituent of green tea, has been shown to exhibit antioxidant and antitumorigenic properties using in vitro and in vivo models of colon cancer and in small cohort studies of colorectal cancer patients. The development of colon cancer is influenced by both genetic and epigenetic factors, with increased risk associated with age, lifestyle, and environmental exposures. Thus, parsing the interactions of genetic components and epigenetic modulators of gene expression in colon cancer development and progression is essential. The mechanism by which EGCG exerts antitumorigenic activity against colon cancer has not been completely elucidated. This study investigates potential mechanism(s) by which EGCG inhibits proliferation of HCT-116 and HT-29 colon cancer cell lines, via epigenetic pathways.

Briefly, HCT-116 and HT-29 cells were treated with EGCG (5-150 µM) and control drugs: 5-FU (50-200 µg/mL), 5-AZA (5 µM), SAHA (1-10 µM), and anacardic acid (10 µM) for 48-72 h. Cell proliferation (MTT), cell cycle and apoptosis (PI-FC and TUNEL), enzyme activity, gene and protein expression were measured. EGCG inhibited proliferation of HCT-116 and HT-29 by promoting S-phase cell cycle arrest and apoptosis. Expression and global enzyme activity of DNMTs (1, 3a, 3b), HDACs (1-4), and HATs (P300, PCAF, P400) were differentially expressed in both cell lines. A consistent upregulation of DNMT3b and downregulation of HDAC3 in both cell lines were observed. Global and gene-specific regulation of DNA methylation and histone acetylation by EGCG is under current study in our lab.

The antiproliferative effects of EGCG can potentially be attributed to restoring normal global and gene-specific methylation/acetylation pattern in colon cancer cells by regulating DNMTs, HDACs, and HATs. This study provides evidence for the utilization of EGCG as a potential chemopreventive agent against colon cancer. Furthermore, identifying mechanisms by which EGCG overrides tumor-driven genetic deregulation to inhibit carcinogenesis expands our knowledge on pathways contributing to colon cancer and plausible targets for epigenetic therapy/prevention.

This project is supported by NIH: RO1CA96694 and P30CA054174.

Citation Format: April B. Cabang, Yuan Fang, Jay Morris, Michael J. Wargovich. Epigallocatechin gallate inhibits colon cancer cell proliferation by modulating epigenetic enzymes (DNMTs, HDACs, and HATs). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 410. doi:10.1158/1538-7445.AM2014-410

Green tea polyphenol epigallocatechin 3-gallate, contributes to the degradation of DNMT3A and HDAC3 in HCT 116 human colon cancer cells

BACKGROUND

Colon cancer is still the second leading cause of cancer deaths in the United States. Epigenetic gene silencing involving DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) plays an important role in the progression of colon cancer.

MATERIALS AND METHODS

In the present study we found that the sensitivity of colon cancer cells to methylation plays a role in its response to alternative therapy involving the green tea polyphenol, epigallocatechin 3-gallate. HDAC and DNMT protein expression were reduced when methylation-sensitive HCT 116 human colon cancer cells was treated with EGCG, but was relatively stable in the HT-29 cell line. This decrease in expression may be partially explained by our finding that DNMT3A and HDAC3 are degraded in the methylation-sensitive colon cancer cells in part by inhibiting their association with the E3 ubiquitin ligase, UHRF1.

CONCLUSION

These findings provide a rationale for the development of a targeted therapy for methylation-sensitive colon cancer that can include EGCG in combination with other DNMT and HDAC inhibitors.

Epigenetic mechanisms underlying diet-sourced compounds in the prevention and treatment of gastrointestinal cancer

The development of colon cancer, the third most diagnosed cancer and third leading cause of cancer deaths in the United States, can be influenced by genetic predispositions and environmental exposures. As 80% of colon cancer cases are sporadic in nature, much interest lies in determining risk factors that may foster its development, as well as identifying compounds that could inhibit colon cancer development or halt progression. A major risk factor for sporadic colon cancer is a high fat, Western diet which has been linked to a cancer-prone, pro-inflammatory state. Cultures which place an emphasis on fresh fruits and vegetables demonstrate lower colon cancer incidences. Diet not only has the potential to encourage colon cancer development, but recent evidence demonstrates that certain dietary natural products can halt colon cancer development and progression via epigenetic regulation. Epigenetic dysregulation may contribute to inflammation-driven diseases, such as cancer, and can lead to the inappropriate silencing of genes necessary to inhibit cancer development. Natural compounds have shown the ability to reverse epigenetic dysregulation in in vitro and in vivo models. As current allopathic medicines aimed at reversing epigenetic silencing are accompanied with the risk of toxicity and side effects, much interest lies in being able to harness the disease preventing properties in natural products. Here, we discuss the epidemiology of colon cancer, describe the need for natural approaches to inhibit disease development and highlight natural products which have been shown to inhibit gastrointestinal cancer initiation and progression in vitro or in vivo through epigenetic modulation.

Vitamin D receptor and retinoid X receptor α status and vitamin D insufficiency in models of murine colitis

The anti-inflammatory actions of vitamin D have long been recognized and its importance in modulating colon cancer and colitis development is becoming apparent. The vitamin D receptor (VDR) is downregulated in human ulcerative colitis and colitis-associated cancer (CAC); however, its status in murine models of colitis has yet to be explored. Snail and Snail2, zinc-finger transcription factors regulated by inflammatory pathways and able to transcriptionally silence VDR, are upregulated in human Ulcerative Colitis and are associated with localized VDR silencing. To signal, VDR must heterodimerize with retinoid X receptor α (RXRα). If either VDR or RXRα are compromised, vitamin D cannot regulate inflammatory pathways. RXRα is downregulated in human colorectal cancer, yet its expression in human and murine colitis has yet to be investigated. To explore the importance of vitamin D and VDR in murine colitis, we used acute and chronic azoxymethane/dextran sulfate sodium models of murine colitis. VDR was downregulated early in the onset of colitis, whereas RXRα downregulation only occurred as colitis became chronic and developed into CAC. Receptor downregulation was associated with an early increase in the expression of the inflammatory markers, Snail and Snail2. The acute colitis model induced in combination with a vitamin D-deficient diet resulted in increased morbidity, receptor downregulation, inflammatory marker expression, and Snail and Snail2 upregulation. These experiments show the importance of vitamin D and VDR in modulating murine colitis development.

Racial disparities in advanced-stage colorectal cancer survival

PURPOSE

African-Americans (AA) have a higher incidence of and lower survival from colorectal cancer (CRC) compared with European Americans (EA). In the present study, statewide, population-based data from South Carolina Central Cancer Registry are used to investigate the relationship between race and age on advanced-stage CRC survival.

METHODS

The study population was comprised of 3,865 advanced pathologically documented colon and rectal adenocarcinoma cases diagnosed between 01 January 1996 and 31 December 2006: 2,673 (69 %) EA and 1,192 (31 %) AA. Kaplan-Meier methods were used to generate median survival time and corresponding 95 % confidence intervals (CI) by race, age, and gender. Factors associated with survival were evaluated by fitting Cox proportional hazards regression models to generate hazard ratios (HR) and 95 % CI.

RESULTS

We observed a significant interaction between race and age on CRC survival (p = 0.04). Among younger patients (<50 years), AA race was associated with a 1.34 times (95 % CI 1.06-1.71) higher risk of death compared with EA. Among older patients, we observed a modest increase in risk of death among AA men compared with EA [HR 1.16 (95 % CI 1.01-1.32)] but no difference by race between women [HR 0.94 (95 % CI 0.82-1.08)]. Moreover, we observed that the disparity in survival has worsened over the past 15 years.

CONCLUSIONS

Future studies that integrate clinical, molecular, and treatment-related data are needed for advancing understanding of the racial disparity in CRC survival, especially for those <50 years old.

Homeostatic imbalance and colon cancer: the dynamic epigenetic interplay of inflammation, environmental toxins, and chemopreventive plant compounds

The advent of modern medicine has allowed for significant advances within the fields of emergency care, surgery, and infectious disease control. Health threats that were historically responsible for immeasurable tolls on human life are now all but eradicated within certain populations, specifically those that enjoy higher degrees of socio-economic status and access to healthcare. However, modernization and its resulting lifestyle trends have ushered in a new era of chronic illness; one in which an unprecedented number of people are estimated to contract cancer and other inflammatory diseases. Here, we explore the idea that homeostasis has been redefined within just a few generations, and that diseases such as colorectal cancer are the result of fluctuating physiological and molecular imbalances. Phytochemical-deprived, pro-inflammatory diets combined with low-dose exposures to environmental toxins, including bisphenol-A (BPA) and other endocrine disruptors, are now linked to increasing incidences of cancer in westernized societies and developing countries. There is recent evidence that disease determinants are likely set in utero and further perpetuated into adulthood dependent upon the innate and environmentally-acquired phenotype unique to each individual. In order to address a disease as multi-factorial, case-specific, and remarkably adaptive as cancer, research must focus on its root causes in order to elucidate the molecular mechanisms by which they can be prevented or counteracted via plant-derived compounds such as epigallocatechin-3-gallate (EGCG) and resveratrol. The significant role of epigenetics in the regulation of these complex processes is emphasized here to form a comprehensive view of the dynamic interactions that influence modern-day carcinogenesis, and how sensibly restoring homeostatic balance may be the key to the cancer riddle.

Abstract LB-168: A hexane fraction of American ginseng suppresses colon cancer associated with colitis

Patients with Ulcerative Colitis (UC) have a high risk of colon cancer. We have recently shown American Ginseng (AG) suppresses colitis, and prevents colon cancer in mice. In the present study we isolated a Hexane Fraction of AG and found this to have particularly potent anti-oxidant and pro-apoptotic properties. The Hexane Fraction of AG was effective in inducing apoptosis of human epithelial colon cancer cell, HCT-116 and inflammatory cells. As well, this fraction was shown to suppress azoxymethane (AOM)/DSS-induced colon cancer. We performed two studies with mice: a short term (Day 35) and long term (Day 50) cancer prevention study. Mice fed the Hexane fraction of AG had significantly less inflammatory and ulcerative lesions, as well as cancerous lesions compared with the vehicle-treated group in both the short and long-term cancer prevention studies. Results are consistent with the hypothesis that the Hexane fraction of AG has anti-inflammatory and anti-cancer properties, and prevents the progression of colon cancer in AOM/DSS mouse model. Interestingly, at Day 35, following isolation of CD45- epithelial cells from colons of mice treated with either AOM+DSS+Vehicle or AOM+DSS+Hexane fraction of AG, there was a 24% increase in the putatative tumor suppressor miRNA-16 with treatment with the Hexane fraction of AG. When looking at putative miRNAs with oncogenic properties (miRNA-21 and -155), levels were decreased in epithelial cells by 25% and 12% respectively in the Hexane fraction of AG-treated mice. This study provides additional pre-clincal data, and mechanistic studies that support the possible use of this complementary and alternative medicine in the treatment of colitis, and the prevention of colon cancer associated with colitis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-168. doi:1538-7445.AM2012-LB-168

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.

Abstract A40: Epigenetic modification of human colon cancer by the green tea polyphenol EGCG

Silencing of regulatory genes through hypermethylation of CpG islands is an important mechanism in tumorigenesis of numerous cancers. We have previously shown that Retinoid X Receptor alpha (RXRα) is silenced in tumors of the colon cancer AOM-APC/min+ mouse model. Upon treatment with green tea, RXRα expression was restored and intestinal tumorigenesis was inhibited. We examined human colonic tumor microarrays by immunohistochemcial staining and found a marked decrease in RXR expression in tumor tissue compared to normal matched tissues, inversely β-Catenin levels increased. To determine how RXRα loss is reversed in human cancers by green tea, we treated HT-29 (methylation insensitive) and HCT116 (methylation sensitive) human colon cancer cell lines with different concentrations of Epigallocatechin gallate (EGCG - major polyphenolic compound in green tea). We found by western blotting nuclear protein fractions that EGCG can restore RXRα levels in HCT116 cells in a dose dependant manner. Using these same lysates, we probed for presence of the most common DNA Methyltransferases (DNMTs) and Histone Deacetylases (HDACs). We found that expression of DNMTs as well as HDACs was inhibited in a dose dependent manner following treatment with EGCG. Additionally we examined by real time PCR, the message levels of DNMTs in cells treated with EGCG to determine if they correlate with the observed downregulation in protein expression. We can conclude that the silencing of RXRα may be due in part to by repressing effects of EGCG on DNMT as well as HDAC activity. Our results here show that EGCG, a common dietary compound, can modulate the reversal of gene-silencing involved colon carcinogenesis and maybe a possible avenue for colon cancer therapy and demonstrates be one potential mechanism of cancer chemoprevention in green tea that outlines a new epigenetic pathway.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):A40.

Abstract 4616: A hexane extract of American ginseng suppresses mouse colitis

Ulcerative colitis (UC) is a dynamic, idiopathic, chronic inflammatory condition associated with a high colon cancer risk. We have previously shown that American Ginseng (AG) extract prevents and treats colitis. The aim of this study was to better understand the components of American ginseng that suppress colitis. In this study we show that among five different fractions of AG (Butanol, Hexane, Ethylacetate, Dicholoromethane and Water), the Hexane fraction of American ginseng (HAG) has the most effective anti-oxidation and pro-apoptotic effect. This effect of HAG was shown in a mouse macrophage cell line (ANA-1 cells) and in an ex-vivo model (activated primary effector T cells, CD4+/CD25- T cells). Importantly, compared with the entire AG extract, the HAG was more potent in treating colitis in a dextran sulfate sodium (DSS) mouse model. Results from this study move us closer to understanding the molecular components of AG that suppress colitis, and perhaps prevent colon cancer associated with colitis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4616. doi:10.1158/1538-7445.AM2011-4616

Aberrant crypt foci: the case for inclusion as a biomarker for colon cancer

Aberrant crypt foci (ACF) are one of the earliest histopathological manifestations of colon cancer. In this review, we critically present the molecular, cellular, histopathological, and chemopreventive evidence that ACF are relevant biomarkers for colon cancer. The laboratory and clinical evidence are highly suggestive that ACF are in the pathway leading to colon cancer, but not all ACF will do so. The possible fate and outcome of ACF in the progression toward colon cancer may be dependent on a number of features that define their predictive power for the prevention or progression of cancer.

Abstract A95: Epigenetic changes in colon cancer cell lines treated with the green tea polyphenolic, EGCG

Retinoids are known for their role in regulating cell growth and proliferation and for activating tumor suppressor genes. We have previously shown that Retinoid X Receptor alpha (RXRα) is silenced in tumors of the colon cancer AOM-APCMin/+ mouse model. Upon treatment with green tea, RXR expression was restored and intestinal tumorigenesis was inhibited. We hypothesize that tea polyphenols, especially epigallocatechin gallate (EGCG), induce modification of gene expression through effects of DNA methyltransferases (DNMTs) as well as Histone Deacetylases (HDACs). We treated HT-29 and HCT116 colon cancer cells with EGCG concentrations of 0, 50, 100 or 150µM or 5µM of the DNMT inhibitor 5-aza-2dC for 48, 72 and 96 hours as well as for two, three and four doubling times. The cell lines were chosen based on their methylation status. HCT116 cells are more sensitive to promoter region methylation compared to HT-29 cells. Using nuclear fractions of the cell lysates, we probed for presence of the most common DNMTs and HDACs using western blotting. We found that expression of DNMTs as well as HDACs was inhibited in a dose dependent manner following treatment with EGCG. We also found that treatments according to doubling times showed a more profound difference in expression levels when compared to traditional time points. We can conclude that the silencing of RXRα may be due in part to by repressing effects of EGCG on DNMT as well as HDAC activity. This could be one potential mechanism of cancer chemoprevention in green tea that outlines a new epigenetic pathway.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A95.

Epigenetic modulation of the retinoid X receptor alpha by green tea in the azoxymethane-Apc Min/+ mouse model of intestinal cancer

We investigated the possible mechanisms of inhibition of colorectal carcinogenesis by green tea (GT) in azoxymethane-treated (AOM) Apc(Min/+) mice. Mice received water or a 0.6% (w/v) solution of GT as the only source of beverage. GT treatment commenced at the 8th week of age and lasted for 8 wk. The treatment caused a statistically significant reduction in the number of newly formed tumors (28%, P < 0.05). Immunohistochemical analysis showed that GT decreased the levels of beta-catenin and its downstream target cyclin D1. To probe a mechanism, we further investigated the expression of retinoic X receptor alpha (RXR alpha) in AOM/Apc(Min/+) tumors. Our results show that RXR alpha is selectively downregulated in AOM/Apc(Min/+) mouse intestinal tumors. In contrast, other retinoic receptors including retinoic acid receptor alpha (RAR alpha), RAR beta, RXR beta, and RXR gamma were all expressed in Apc(Min/+) adenomas. Furthermore, our results show that RXR alpha downregulation is an early event in colorectal carcinogenesis and is independent of beta-catenin expression. GT significantly increased the protein levels of RXR alpha. In addition, RT-PCR analysis showed that GT induced a similar increase in the levels of RXR alpha mRNA. Genomic bisulfite treatment of colonic DNA followed by pyrosequencing of 24 CpG sites in the promoter region of RXR alpha gene showed a significant decrease in CpG methylation with GT treatment. The results suggest that a low concentration of GT is sufficient to desilence RXR alpha and inhibit intestinal tumorigenesis in the Apc(Min/+) mouse.

Khayanolides from African mahogany Khaya senegalensis (Meliaceae): A revision

Five khayanolides (1-O-acetylkhayanolide B 1, khayanolide B 2, khayanolide E 3, 1-O-deacetylkhayanolide E 4, 6-dehydroxylkhayanolide E 5) were isolated from the stem bark of African mahogany Khaya senegalensis (Meliaceae). Their structures and absolute configurations were determined through extensive spectroscopic analyses including MS, NMR, and single-crystal X-ray diffraction experiments. The results established that two previously reported khayanolides, 1alpha-acetoxy-2beta,3alpha,6,8alpha,14beta-pentahydroxy-[4.2.1(10,30).1(1,4)]-tricyclomeliac-7-oate 6 and 1alpha,2beta,3alpha,6,8alpha,14beta-hexahydroxy-[4.2.1(10,30).1(1,4)]-tricyclomeliac-7-oate 7, were, in fact, 1-O-acetylkhayanolide B 1 and khayanolide B 2, and that the two reported phragmalin derivatives, methyl 1alpha-acetoxy-6,8alpha,14beta,30beta-tetrahydroxy-3-oxo-[3.3.1(10,2).1(1,4)]-tricyclomeliac-7-oate 8 and methyl 1alpha,6,8alpha,14beta,30beta-pentahydroxy-3-oxo-[3.3.1(10,2).1(1,4)]-tricyclomeliac-7-oate 9, were, in fact, khayanolide E 3 and 1-O-deacetylkhayanolide E 4, respectively. Based on the results from this study and consideration of the biogenetic pathway, the methyl 6-hydroxyangolensate in African mahogany K. senegalensis should have a C-6 S configuration while methyl 6-hydroxyangolensate in genuine mahogany Swietenia species should have a C-6 R configuration.

American ginseng suppresses inflammation and DNA damage associated with mouse colitis

Ulcerative colitis (UC) is a dynamic, idiopathic, chronic inflammatory condition associated with a high colon cancer risk. American ginseng has antioxidant properties and targets many of the players in inflammation. The aim of this study was to test whether American ginseng extract prevents and treats colitis. Colitis in mice was induced by the presence of 1% dextran sulfate sodium (DSS) in the drinking water or by 1% oxazolone rectally. American ginseng extract was mixed in the chow at levels consistent with that currently consumed by humans as a supplement (75 p.p.m., equivalent to 58 mg daily). To test prevention of colitis, American ginseng extract was given prior to colitis induction. To test treatment of colitis, American ginseng extract was given after the onset of colitis. In vitro studies were performed to examine mechanisms. Results indicate that American ginseng extract not only prevents but it also treats colitis. Inducible nitric oxide synthase and cyclooxygenase-2 (markers of inflammation) and p53 (induced by inflammatory stress) are also downregulated by American ginseng. Mucosal and DNA damage associated with colitis is at least in part a result of an oxidative burst from overactive leukocytes. We therefore tested the hypothesis that American ginseng extract can inhibit leukocyte activation and subsequent epithelial cell DNA damage in vitro and in vivo. Results are consistent with this hypothesis. The use of American ginseng extract represents a novel therapeutic approach for the prevention and treatment of UC.

Ginkgo biloba extract EGb 761 has anti-inflammatory properties and ameliorates colitis in mice by driving effector T cell apoptosis

Ulcerative colitis is a dynamic, chronic inflammatory condition of the colon associated with an increased colon cancer risk. Ginkgo biloba is a putative antioxidant and has been used for thousands of years to treat a variety of ailments. The aim of this study was to test whether the standardized G.biloba extract, EGb 761, is an antioxidant that can be used to prevent and treat colitis in mice. Here, we show that EGb 761 suppresses the activation of macrophages and can be used to both prevent and treat mouse colitis. Markers of inflammation (iNOS, Cox-2 and tumor necrosis factor-alpha) and inflammatory stress (p53 and p53-phospho-serine 15) are also downregulated by EGb 761. Furthermore, we show that EGb 761 reduces the numbers of CD4+/CD25-/Foxp3- effector T cells in the colon. Interestingly, EGb 761 drives CD4+ effector T cell apoptosis in vitro and in vivo, providing a mechanistic explanation to the reduction in numbers of this cell type in the colon. This current study is in agreement with previous studies supporting a use of EGb 761 as a complementary and alternative strategy to abate colitis and associated colon cancer.

Effect of orlistat on fecal fat, fecal biliary acids, and colonic cell proliferation in obese subjects

BACKGROUND & AIMS

Orlistat is a weight management agent that selectively inhibits gastrointestinal lipase activity. Because of orlistat's mode of action, increased fecal fat is presented to the colonic mucosa, and fecal bile acid and free fatty acid composition may be altered during treatment. Our aim was to assess the effect of treatment of obese subjects with orlistat 120 mg 3 times a day for 6 weeks on fecal lipid and bile acid parameters and colonic mucosal cell proliferation.

METHODS

Twenty-four obese (body mass index, 30-40 kg/m2) but otherwise healthy male and female subjects were enrolled in a single-center, randomized, double-blind, placebo-controlled, parallel-group study. Participants were hospitalized during days 1-3 and 33-42 of treatment and were treated as outpatients for the remaining days.

RESULTS

Treatment with orlistat for 6 weeks resulted in significantly greater increases in fecal weight, total fecal fat, and fecal free fatty acids than placebo. Total fecal bile acid amounts decreased slightly with orlistat, and increased significantly with placebo treatment (P < .05 between-group difference). Orlistat did not alter colonic cell proliferation as assessed by the 3 proliferative indices (5-bromo-2-deoxyuridine, whole crypt mitotic count, and proliferating cell nuclear antigen).

CONCLUSIONS

Biochemical changes in fecal composition related to the pharmacodynamic mode of action of orlistat are not accompanied by altered colonic cell proliferation, a putative biomarker of colon cancer risk.

Clinical validation of breast cancer biomarkers using tissue microarray technology

The results of previous studies done in our laboratory on breast cancer gene expression profile, using DNA microarrays, led to the discovery of several genes associated with breast cancer progression. Further evaluation of these genes and their involvement at various stages of cancer progression required performance of immunohistochemistry on thousands of different tissue blocks. Tissue microarray (TMA) technology facilitates rapid translation of DNA microarrays results to clinical specimens by using immunohistochemical analysis of protein expression. DNA microarray analysis done in our laboratory showed a significantly higher expression of prostatic-specific antigen (PSA) in invasive ductal carcinomas as compared to ductal carcinoma in situ, a finding contrary to the previously published data for PSA immunoreactivity in breast carcinomas. To find out whether TMA strategy could be used to explore the expression of the candidate genes involved in the breast cancer progression, we constructed a breast cancer progression TMA. It consisted of 2 normal ductal epithelium, 8 ductal carcinoma in situ, 19 invasive ductal carcinomas, and 3 metastatic ductal carcinomas of breast in triplets. Two prostatic adenocarcinomas and 2 normal colons were used as positive and negative controls, respectively. We first used well-documented and well-tested markers, such as antibodies to estrogen receptor, progesterone receptor, and p53. Results of these 3 antibodies were according to the previously published data. To validate our result, we then used antibody to PSA and looked for the expression of this protein on breast cancer progression TMA. Except for the 2 positive controls all 98 cores were found to be negative for PSA expression highlighting the importance of validation studies for DNA microarray results.

Green tea selectively targets initial stages of intestinal carcinogenesis in the AOM-ApcMin mouse model

One of the liabilities of the Apc(Min) mouse as a model for colon cancer is its lack of a robust tumor response in the large bowel. In our protocol, we treated the Apc(Min) mouse with azoxymethane, a colon-selective carcinogen. This protocol induced a 4-fold increase in the number of colon tumors. We utilized this protocol to investigate the possible mechanisms of inhibition of colorectal carcinogenesis by green tea. Mice received water or a 0.6% (w/v) solution of green tea as the only source of beverage. Green tea treatment commenced at the eighth week of age and lasted for either 4 or 8 weeks. Green tea significantly inhibited the formation of new adenomas, but was ineffective against larger tumors. Mechanistically, we investigated the effects of green tea on the expression of biomarkers involved in colon carcinogenesis. Western blotting analysis showed that green tea decreased the total levels of the early carcinogenesis biomarker beta-catenin and its downstream target cyclin D1. In contrast, the expression of COX-2 was not altered. Immunohistochemical analysis showed that green tea inhibited the formation of adenomas overexpressing beta-catenin and cyclin D1, but did not reduce the number of COX-2-expressing adenomas. Our results suggest that green tea specifically targets initial stages of colon carcinogenesis; the time of administration of green tea is pivotal for effective chemoprevention. Beverage levels of green tea do not inhibit the progress of any large adenomas or adenocarcinomas existing prior to the tea administration.

Anticancer activity of limonoid from Khaya senegalensis

Two limonoids were isolated from the methanol extract of Khaya senegalensis (Meliaceae), and their structures were identified as 3alpha,7alpha-dideacetylkhivorin (1) and 1-O-acetylkhayanolide B (2) on the basis of MS and NMR spectral data. Complete assignments of (1)H and (13)C chemical shifts for compounds 1 and 2 were achieved by means of 1D and 2D NMR including DEPT, (1)H-(1)H COSY, HMQC, HMBC experiments. Compound 1 showed significant growth inhibitory activities against MCF-7, SiHa and Caco-2 cells with IC(50) values in the range of 0.07-0.14 microm (35-69 ppm) while compound 2 did not.

Inflammation, cancer, and targets of ginseng

Chronic inflammation is associated with a high cancer risk. At the molecular level, free radicals and aldehydes, produced during chronic inflammation, can induce deleterious gene mutation and posttranslational modifications of key cancer-related proteins. Other products of inflammation, including cytokines, growth factors, and transcription factors such as nuclear factor kappaB, control the expression of cancer genes (e.g., suppressor genes and oncogenes) and key inflammatory enzymes such as inducible nitric oxide synthase and cyclooxygenase-2. These enzymes in turn directly influence reactive oxygen species and eicosanoid levels. The procancerous outcome of chronic inflammation is increased DNA damage, increased DNA synthesis, cellular proliferation, disruption of DNA repair pathways and cellular milieu, inhibition of apoptosis, and promotion of angiogenesis and invasion. Chronic inflammation is also associated with immunosuppression, which is a risk factor for cancer. Current treatment strategies for reactive species overload diseases are frequently aimed at treating or preventing the cause of inflammation. Although these strategies have led to some progress in combating reactive species overload diseases and associated cancers, exposure often occurs again after eradication, treatment to eradicate the cause fails, or the treatment has long-term side effects. Therefore, the identification of molecules and pathways involved in chronic inflammation and cancer is critical to the design of agents that may help in preventing the progression of reactive species overload disease and cancer associated with disease progression. Here, we use ginseng as an example of an antiinflammatory molecule that targets many of the key players in the inflammation-to-cancer sequence.

Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits cyclooxygenase-2 expression in colon carcinogenesis

Tea, one of the most widely consumed beverages worldwide, has been shown to have anti-cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX-2) occurs during colon tumorigenesis and inhibition of COX-2 by non-steroidal anti-inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti-cancer effect associated with green tea impacted COX-2 expression levels, human colorectal cancer cell lines HT-29 and HCA-7, were treated with (-)-epigallocatechin-3-gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX-2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX-2 expression were examined. We observed that EGCG down regulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX-2 expression resulted in decreased COX-2 promoter activity via inhibition of nuclear factor kappaB (NF-kappaB) activation. EGCG also promoted rapid mRNA decay mediated through the COX-2 3'untranslated region (3'UTR). In conclusion, these data suggest that inhibition of COX-2 is a mechanism for the anti-proliferative effect of green tea and emphasizes the role that dietary factors have as anti-cancer agents.

Chemopreventive effects of Khaya senegalensis bark extract on human colorectal cancer

An extract of the bark of Khaya senegalensis is commonly used in African traditional medicine for pain and inflammation. Khaya senegalensis bark extract (KSBE) was hypothesized to contain inhibitors of the cyclooxygenase-2 (COX-2) gene and to be useful in the prevention and treatment of colorectal cancer. The diphenyl-2-picrylhydrazyl (DPPH)- free radical activity and the total phenolic content of KSBE were measured, followed by an investigation of cell growth inhibition, COX and prostaglandin E 2 (PGE2) suppression, as well as apoptosis by Western blot analysis and ELISA. Our data clearly showed that KSBE displays anti-proliferative, antiinflammatory and pro-apoptotic effects on HT-29, HCT-15 and HCA-7 cells. Since all three cell lines, irrespective of COX-2 status (HCT-15 is COX-2-deficient), were affected by the treatment, it can be concluded that both COX-dependent and COX-independent pathways are activated by KSBE.

Diallylsulfide and allylmethylsulfide are uniquely effective among organosulfur compounds in inhibiting CYP2E1 protein in animal models

Garlic is a popular culinary herb that is also used throughout the world as a traditional medicine for the prevention and treatment of disease. Epidemiologic studies have suggested that long-term consumption of garlic reduces risk for certain cancers, most notably stomach and colon cancer. This article summarizes the key findings behind one important mechanism explaining the anticarcinogenic effects of garlic-derived agents in animal models: the inhibition of cytochrome p4502E1 (CYP2E1), with some commentary on other aspects of carcinogen metabolism modified by these unique phytochemicals.

Modulation of cytochrome P450 enzymes by organosulfur compounds from garlic

Organosulfur compounds (OSCs) derived from garlic have been studied for the ability to inhibit experimental cancer in various animal models, primarily through modification of carcinogen detoxification enzymes, such as cytochrome P450 (CYP) enzymes. OSCs vary in structural and physical properties, and a detailed analysis of these properties has not been performed with respect to their ability of inhibit chemically-induced colon cancer development. Gastric intubation of rats with a single dose of 200 mg/kg diallyl sulfide (DAS), diallyl disulfide (DADS), and allyl methyl sulfide (AMS) decreased hepatic CYP2E1 protein by 45%, 25% and 47%, respectively, and this inhibition was sustained after 1, 4 and 8 weeks of treatment by these compounds. Dipropyl sulfide (DPS), dipropyl disulfide (DPDS), propyl methyl sulfide (PMS) and S-allylcysteine (SAC) did not inhibit hepatic CYP2E1 protein expression, nor did any of the OSCs affect CYP2E1 mRNA levels. A single dose of 200 mg/kg DAS and AMS increased hepatic CYP1A2 protein (but not mRNA) by 282% and 70%, and DAS increased CYP1A1 protein levels by 684%. Daily treatment for 1, 4 and 8 weeks with 200 mg/kg DAS and AMS resulted in time-dependent increases in hepatic CYP1A1 and CYP1A2 protein levels to a maximum of 600% and 50% for DAS, and 1600% and 240% for AMS after 8 weeks. Dosing with 200 mg/kg of each of the OSCs used in this study increased hepatic CYP3A2 protein levels at all time points. Dosing for 8 weeks with 200 mg/kg DAS, but not AMS or lower doses of DAS, induced bile duct obstruction and focal areas of necrosis. These results indicate that OSCs present in garlic, including DAS and AMS, may be beneficial in inhibiting chemically-induced colon cancer, but that longer dosing with higher concentrations of DAS may elicit minor hepatic toxicity.

Sphingosine kinase 1 is up-regulated in colon carcinogenesis

Sphingosine kinase 1 (SK1) phosphorylates sphingosine to form sphingosine 1-phosphate (S1P), which has the ability to promote cell proliferation and survival and stimulate angiogenesis. The SK1/S1P pathway also plays a critical role in regulation of cyclooxygenase-2 (COX-2), a well-established pathogenic factor in colon carcinogenesis. Therefore, we examined the expression of SK1 and COX-2 in rat colon tumors induced by azoxymethane (AOM) and the relationship of these two proteins in normal and malignant intestinal epithelial cells. Strongly positive SK1 staining was found in 21/28 (75%) of rat colon adenocarcinomas induced by AOM, whereas no positive SK1 staining was observed in normal mucosa. The increase in SK1 and COX-2 expression in AOM-induced rat colon adenocarcinoma was confirmed at the level of mRNA by real-time RT-PCR. In addition, it was found that 1) down-regulation of SK1 in HT-29 human colon cancer cells by small interfering RNA (siRNA) decreases COX-2 expression and PGE2 production; 2) overexpression of SK1 in RIE-1 rat intestinal epithelial cells induces COX-2 expression; and 3) S1P stimulates COX-2 expression and PGE2 production in HT-29 cells. These results suggest that the SK1/S1P pathway may play an important role in colon carcinogenesis, in part, by regulating COX-2 expression and PGE2 production.

Anti-proliferative effects of green tea polyphenol EGCG on Ha-Ras-induced transformation of intestinal epithelial cells

Oncogenic Ras mutations are frequently observed in colorectal cancer and participate in neoplastic transformation of intestinal epithelial cells. Accumulating evidence demonstrates the chemopreventive properties of green tea on colon carcinogenesis. Here we investigated the major green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), to inhibit proliferation of intestinal epithelial cells (RIE-1) transfected with an inducible Ha-Ras(Val12) cDNA. EGCG inhibited cell proliferation induced by oncogenic Ras and blocked cell cycle transition at G1 phase via inhibition of cyclin D1 expression. The EGCG IC(50) was 42microM in transformed cells and 81microM in non-transformed cells. EGCG also promoted E-cadherin expression, which is downregulated by Ras transformation. This study demonstrates the potential of the natural compound EGCG as an effective adjuvant therapy for colon tumors bearing Ras mutations.

Novel genetic variations of the p53R2 gene in patients with colorectal adenoma and controls

AIM: p53-Inducible ribonucleotide reductase small subunit 2 (p53R2) encodes a 351-amino-acid peptide, which catalyzes conversion of ribonucleoside diphosphates to the corresponding deoxyribonucleotides required for DNA replication and repair. A recent study reported that a point mutation (G/T) in the p53 binding sequence in a colon cancer cell line completely impaired p53R2 protein activity.

METHODS: We screened the p53R2 gene coding regions and a regulatory region which contains a p53 binding sequence in 100 patients with colorectal adenoma and 100 control subjects using PCR, cold SSCP, and direct DNA sequencing.

RESULTS: Although we did not identify genetic variation in all nine exons, four regulatory-region variants were found, of which three were single nucleotide polymorphisms (SNPs) (nt 1 789 C/G, nt 1 928 A/G, 1 933 T/C), and one was 20 bp insertion which replaced a ATTTT between nt 1 831 and 1 835. Additionally, we determined the frequency of these p53R2 variants in a recently concluded case-control study of incident sporadic colorectal adenomas (163 cases and 210 controls).

CONCLUSION: Although more detailed functional characterizations of these polymorphisms remain to be undertaken, these polymorphic sites may be useful for identifying alleles associated with mis-splicing, additional transcript factors and, more generally, in cancer-susceptibility association studies.

Histamine receptor antagonists and incident colorectal adenomas

BACKGROUND

Prior studies suggest that histamines may modulate the development of colorectal neoplasia.

AIM

To assess whether histamine receptor antagonist use was associated with adenoma formation.

METHODS

Patients (n = 2366) were drawn from three adenoma chemoprevention trials. All underwent baseline colonoscopy with removal of adenoma(s) and were deemed free of remaining lesions; they were followed with surveillance colonoscopy. Medication use was assessed by questionnaire. Adjusted risk ratios for adenoma formation related to histamine receptor antagonist use (histamine H1 and H2 receptor, H1RA and H2RA) were determined using log linear models.

RESULTS

In pooled analyses, H1RA exposure was not associated with subsequent adenoma risk (RR = 1.10; 95% CI 0.97-1.25) or multiple adenoma formation (RR = 0.85; 95% CI 0.67-1.07). H2RA use also was not associated with adenoma (RR = 0.90; 95% CI 0.77-1.06), or multiple adenoma (RR = 0.77; 95% CI 0.57-1.04) in the pooled analyses, but H2RA users in the first trial had a decreased risk of adenoma (RR = 0.70; 95% CI 0.48-1.03) and multiple adenoma (RR = 0.31; 95% CI 0.12-0.79).

CONCLUSION

H2RA use was associated with reduced risk for adenoma in one trial, but not in the pooled analyses. Further study would be warranted before undertaking randomized trials of H2RAs for adenoma chemoprevention.

Modulation of aberrant crypt foci and apoptosis by dietary herbal supplements (quercetin, curcumin, silymarin, ginseng and rutin)

It is estimated that one-third of Americans use dietary herbal supplements on a regular basis. Diets rich in bioactive phytochemicals are associated with reduced risk of certain cancers, notably, colon cancer. Herbal supplements have not been directly tested as sources of bioactive cancer preventives. Hence, this study compares the ability of four herbal flavonoids (quercetin, curcumin, rutin and silymarin) and one whole herb mixture (ginseng powder) to suppress aberrant crypt foci (ACF) in an azoxymethane (AOM)-induced rat colon cancer model. Second, this study examines the effect of these herbal compounds on apoptosis and the mechanisms by which these compounds evoke apoptosis. The results of this study show that diets containing quercetin, curcumin, silymarin, ginseng and rutin decreased the number of ACFs by 4-, 2-, 1.8-, 1.5- and 1.2-fold, respectively compared with control. Histological analysis of the colon mucosa revealed that all the herbal supplements, except silymarin, induced apoptosis, with quercetin being the most potent (3x increase compared with control). Furthermore, ginseng and curcumin were region-specific in inducing apoptosis. The ability of quercetin and curcumin to modulate ACFs correlates well with their ability to induce apoptosis. Western blot analysis of caspase 9, Bax (proapoptotic) and Bcl-2 (antiapoptotic) proteins from the colon scraping suggests that quercetin and curcumin induce apoptosis via the mitochondrial pathway. Taken together, the results of this study suggest that these herbal supplements may exert significant and potentially beneficial effects on decreasing the amount of precancerous lesions and inducing apoptosis in the large intestine.

Expression of cellular adhesion proteins and abnormal glycoproteins in human aberrant crypt foci

Aberrant crypt foci (ACFs) may be the earliest recognizable histologic precursor lesion for colon cancer. ACF may develop from a complex of events, including the development of cryptal hyperproliferation, defects in the rate of apoptosis, and abnormalities in cellular adhesion. In this study, we hypothesized that human ACF would exhibit discrete differences in cell adhesion proteins compared with normal mucosa of biologic markers associated with colon cancer. ACFs were isolated from resected colon mucosa from 45 patients undergoing surgery for colon cancer. We evaluated the protein expression of 3 biologic markers that may be related to the progression of aberrant crypt foci to tumors: carcinoembryonic antigen, E-cadherin, and sialyl Tn antigen. In general, ACFs located near cancers in the right colon were more often hyperplastic than dysplastic; this was more noticeable in the left colon. Carcinoembryonic antigen expression was found to be more intense in apical portions of ACF crypts, with sialyl Tn antigen moderately increased, whereas E-cadherin diffusely stained throughout crypts within ACFs. There are significant biologic changes in potential tumor markers that accompany the early transformation of the normal glandular epithelium, some of which are expressed very early in the colon at the stage of appearance of ACF.

Methodologic considerations in the study of diet as part of complementary and alternative medicine modalities

Diet is an essential component of most comprehensive health systems. Food figures prominently in the consciousness of most individuals, and the sensations of taste and smell are fundamentally important in human emotion. Complex configurations of dietary sanctions and strictures exist in virtually every human society, providing additional force to the power of diet. A wide variety of epidemiologic and laboratory-based studies have implicated a number of specific dietary factors in health and disease, with the former producing much in the way of equivocal evidence on most diet-health relationships and the latter often focusing so narrowly as to call into question the relevance of findings to human health. Assessing the role of diet as an important component of complementary and alternative medical treatment and preventive strategies will require a broad understanding of methodologic issues. Careful consideration of what is required to answer substantive questions in this intriguing and important area also will serve to advance the study of complementary and alternative modalities more generally.

Combinatorial chemoprevention: efficacy of lovostatin and exisulind on the formation and progression of aberrant crypt foci

BACKGROUND

There are several advantages to combinatorial chemoprevention strategies over monotherapeutic approaches. Both the HMG-CoA reductase inhibitor (HRI) lovastatin (LOV) and the selective apoptotic antineoplastic drug (SAAND) exisulind (EXS) have shown remarkable chemopreventive effects in previous studies, in cell lines and limited studies in rodents. Here, experiments were designed to assess the potential use of these two compounds in combinatorial chemoprevention therapy, using two bio-assays in which inhibition of the carcinogen-induced preneoplastic lesions, aberrant crypt foci (ACF), was used to quantitate efficacy.

MATERIALS AND METHODS

ACF were induced by the carcinogen azoxymethane (AOM) in F344 rats by two sequential weekly i.p. injections at a dose of 15 mg/kg. F344 rats were fed seven experimental diets containing LOV @ 50 parts per million (ppm), EXS @ 100, 250 and 1000 ppm and combination diets containing EXS at 100, 250 and 1000 ppm, each combined with LOV @ 50 ppm. Quantification of ACF number and type (singlet, doublet, triplet and four or more) was performed on whole mounts of rat colons stained with 1.0% methylene blue.

RESULTS

During the initiation protocol, administration of LOV @ 50 ppm alone and the combination of LOV @ 50 ppm with EXS @ 1000 ppm significantly decreased the mean number of ACF when compared to the positive control by 49% and 47%, respectively; however EXS @ 250 ppm displayed tumor promoting effects by significantly increasing the mean number of ACF by 64%. The post-initiation protocol administration of EXS @ 100, 250 and 1000 ppm and the combinations of LOV @ 50 ppm with EXS @ 100 and 250 ppm significantly increased the mean number of ACF when compared to the positive control by 44%, 48%, 55%, 49% and 40%, respectively.

CONCLUSION

LOV shows greater promise than EXS in fulfilling the role as a supplemental chemopreventive agent in combinatorial chemopreventive strategies for cancers such as colon cancer. EXS did not augment this activity, failing to enhance chemopreventive therapy in this animal model.

Polymorphism of the cyclin D1 gene, CCND1, and risk for incident sporadic colorectal adenomas

Cyclin D1, encoded by the CCND1 gene and activated by the adenomatous polyposis coli-beta-catenin-T-cell factor/lymphoid enhancing factor pathway, induces G(1) to S-phase cell cycle transition, promoting cell proliferation. A recently described codon 242, exon 4, G to A single nucleotide polymorphism (A870G) produces a longer half-life cyclin D1. To investigate whether CCND1 genotype influences risk for colorectal adenoma, we genotyped CCND1 by PCR/RFLP on 161 incident sporadic adenoma cases and 213 controls ages 30-74 years in a North Carolina colonoscopy-based case-control study. At least one polymorphic A allele was found in 68% of cases and 60% of controls. Having an A allele was associated with increased risk for adenoma: the age- and sex-adjusted odds ratio (OR) was 1.5 [95% confidence interval (CI) 1.0-2.4], a finding that was stronger for those whose adenomas were multiple (OR 2.9, 95% CI 1.4-6.0), larger (>or=1 cm; OR 2.4, 95% CI 1.2-4.8), had moderate to severe dysplasia (OR 2.1, 95% CI 1.1-3.8), or were in the right side of the colon (OR 3.6, 95% CI 1.3-10.0). Joint risk factor multivariate analyses revealed stronger positive associations among those who were older (>57 years; OR 2.8, 95% CI 1.4-5.5), male (OR 2.8, 95% CI 1.3-5.7), currently smoked (OR 2.7, 95% CI 1.3-5.7), or currently drank alcohol (OR 2.2, 95% CI 1.2-4.2) if they had an A allele and stronger inverse associations among those who used nonsteroidal anti-inflammatory drugs (OR 0.4, 95% CI 0.2-0.9) or had higher calcium intakes (OR 0.4, 95% CI 0.2-0.9) if they had no A allele. These data support the hypothesis that the CCND1 A870G polymorphism may increase risk for colorectal neoplasms.

The Role of Dietary Supplements during Cancer Therapy

This guide was compiled after recommendations by the American Institute for Cancer Research (AICR) Cancer Resource Advisory Council. It encompasses the AICR position on current issues in nutrition for cancer survivors during treatment and is intended to provide advice about dietary supplements for cancer survivors who are still being treated. Current scientific findings about the safety and effectiveness of some commonly used dietary antioxidants and nonantioxidant supplements during chemotherapy are presented and assessed. Use of dietary supplements during cancer treatment remains controversial. Patients are cautioned that vitamin and mineral supplements as therapies are not substitutes for established medicine. The current recommendation for cancer patients is to only take moderate doses of supplements because evidence from human clinical studies that confirm their safety and benefits is limited. A daily multivitamin containing supplements at the levels of the Dietary Reference Intakes can be used safely as part of a program of healthy nutrition. In addition, the AICR Cancer Resource Advisory Council concluded that further scientific research is needed to provide a set of firm guidelines for the use of vitamin and mineral supplements by cancer patients during treatment.

Diet, individual responsiveness and cancer prevention

Dietary recommendations for the prevention of cancer have been based predominantly on large epidemiological studies of diet and lifestyle, conducted 20, and in some cases, almost 30 years ago. Government programs have been successful in educating the public about the benefits of eating fruits and vegetables, yet despite these efforts, Americans have become heavier, diabetes is more prevalent and general health indicators have not greatly improved. Individual response to dietary recommendations may be complicated by a variety of factors. Polymorphisms in genes related to drug activation and detoxification, folate metabolism, DNA repair, vitamin receptors and other cellular receptors could account for a lack of benefit at the level of the individual for consuming cancer preventive foods. Beyond consideration of genetic polymorphisms, the last half century has brought stark changes in lifestyle that depart from normal diurnal cycle and periodic fluctuations in food availability. Thus, modern times may be characterized as being constantly in a "feast" environment. The cellular consequences may be an increase in risk for several diseases including cancer.