Molecular mechanisms for chemoprevention of colorectal cancer by natural dietary compounds

Synthesis and antitumor activity of bis(hydroxymethyl)propionate analogs of pterostilbene in cisplatin-resistant human oral cancer cells

The aim of this study was to develop a new drug substance with low toxicity and effective inhibitory activity against cisplatin-resistant oral cancer. The naturally produced pterostilbene was selected as the lead compound for design and synthesis of a series of bis(hydroxymethyl)propionate-based prodrugs. All derivatives were screened for antiproliferative effects against the cisplatin-resistant oral squamous (CAR) cell line and the results indicated that several compounds demonstrated superior inhibitory activity compared with pterostilbene and resveratrol. Among them, the most promising compound, 12, was evaluated for in vivo antitumor activity in a CAR xenograft nude mouse model. Obvious antitumor activity was observed at the lowest oral dose (25 mg/kg/day). Increasing the dose of 12 to 100 mg/kg/day reduced the tumor size to 22% of the control group. Based on these findings as well as the extremely low toxicity seen in the in vivo studies, we believe that compound 12 could serve as a new lead for further development.

Pharmacokinetics, bioavailability, tissue distribution and excretion of tangeretin in rat

Tangeretin, 4′,5,6,7,8-pentamethoxyflavone, is one of the major polymethoxyflavones (PMFs) existing in citrus fruits, particularly in the peels of sweet oranges and mandarins. Tangeretin has been reported to possess several beneficial bioactivities including anti-inflammatory, anti-proliferative and neuroprotective effects. To achieve a thorough understanding of the biological actions of tangeretin in vivo, our current study is designed to investigate the pharmacokinetics, bioavailability, distribution and excretion of tangeretin in rats. After oral administration of 50 mg/kg bw tangeretin to rats, the C_max, T_max and t_1/2 were 0.87 ± 0.33 μg/mL, 340.00 ± 48.99 min and 342.43 ± 71.27 min, respectively. Based on the area under the curves (AUC) of oral and intravenous administration of tangeretin, calculated absolute oral bioavailability was 27.11%. During tissue distribution, maximum concentrations of tangeretin in the vital organs occurred at 4 or 8 h after oral administration. The highest accumulation of tangeretin was found in the kidney, lung and liver, followed by spleen and heart. In the gastrointestinal tract, maximum concentrations of tangeretin in the stomach and small intestine were found at 4 h, while in the cecum, colon and rectum, tangeretin reached the maximum concentrations at 12 h. Tangeretin excreted in the urine and feces was recovered within 48 h after oral administration, concentrations were only 0.0026% and 7.54%, respectively. These results suggest that tangeretin was mainly eliminated as metabolites. In conclusion, our study provides useful information regarding absorption, distribution, as well as excretion of tangeretin, which will provide a good base for studying the mechanism of its biological effects.

Butyrate, a dietary fiber derivative that improves irinotecan effect in colon cancer cells

A diet rich in fiber is associated with a low risk of developing colorectal cancer. Dietary fiber fermentation by intestinal microflora results in the production of butyrate, which has been reported as a chemopreventive agent and a histone deacetylase inhibitor (HDACi). Irinotecan is used as second-line treatment and induces adverse effects with serious life-threatening toxicities in at least 36% of patients. Our study intends to find a synergy that could improve the efficacy and decrease the toxicity of chemotherapy. Results demonstrate that milimolar concentrations of butyrate has an anti-proliferative effect in all three colon cancer cell lines under study, leading to a decrease on cell viability, expression of P21, P53 and β-catenin, being able to modulate P-glycoprotein activity and to induce apoptosis by modulation of BAX/BCL-2 ratio. Combined therapy has a cytotoxic potential, resulting in a synergistic effect, and allows a reduction in irinotecan concentration needed to reduce IC₅₀. This potential was verified in terms of cell viability and death, cell cycle and expression of P21 and P53. Butyrate and irinotecan act synergistically in the three cancer cell lines, despite the different genetic background and location, and inhibited tumor growth in a xenograft model. Butyrate is able to influence the mechanism of LS1034 cell line chemoresistance. Butyrate in combination with chemotherapeutic agents has an important role for the treatment of colorectal cancer. Such understanding can guide decisions about which patients with colorectal cancer may benefit from therapy with butyrate demonstrating the important role of diet in colorectal cancer treatment.

Chemopreventive Effect of Aster glehni on Inflammation-Induced Colorectal Carcinogenesis in Mice

Although Aster glehni is a common dietary herb that has various bioactivities, including anti-diabetic, anti-adipogenic, and anti-inflammatory effects, A. glehni has not been studied in colon cancer. Therefore, we hypothesized the chemopreventive effects of an ethanol extract of A. glehni (AG) on azoxymethane/dextran sulfate sodium (AOM/DSS)-induced colitis-associated cancer (CAC) in mice. In this study, we found that treatment with AG significantly attenuated the AOM/DSS-induced enlargement of the spleen and shortening of the colon. In addition, colonic tumor formation, colonic damage, and increased muscle thickness were significantly reduced in AOM/DSS-induced mice fed AG. Treatment with AG also reduced intestinal interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α production and decreased inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 protein expression in mice with AOM/DSS-induced CAC. Furthermore, AG reduced nuclear factor (NF)-κB activation via phosphorylation and degradation of inhibitor of kappa Bα (IκBα), leading to inhibition of NF-κB p65 nuclear translocation. It also downregulated the expression of NF-κB-related proteins, including the B-cell lymphoma 2 (Bcl-2) family and inhibitors of apoptosis proteins (IAPs), in mice with AOM/DSS-induced CAC. Taken together, these findings suggest that the treatment with AG inhibited colitis-associated colon carcinogenesis in mice, and this chemopreventive effect was strongly mediated by suppression of the NF-κB signaling pathway, indicating that AG could be a promising protective agent against CAC.

Wnt Signalling-Targeted Therapy in the CMS2 Tumour Subtype: A New Paradigm in CRC Treatment?

Colorectal cancers (CRC) belonging to the consensus molecular subtype 2 (CMS2) have the highest incidence rate, affect mainly the distal colon and rectum, and are characterized by marked Wnt/β-catenin/Transcription Factor 7-Like 2 (TCF7L2) pathway activation and also by activation of epidermal growth factor receptor (EGFR) signalling. Despite having the highest overall survival, CMS2 tumours are often diagnosed at stage III when an adjuvant chemotherapy-based regimen is recommended. Nevertheless, colorectal cancer stem cells (CSCs) and circulating tumour cells may still evade the current therapeutic options and metastasize, stressing the need to develop more tailored therapeutic strategies. For example, activation of EGFR signalling is being used as a target for tailored therapy, however, therapy resistance is frequently observed. Therefore, targeting the Wnt signalling axis represents an additional therapeutic strategy, considering that CMS2 tumours are "Wnt-addicted". Several efforts have been made to identify Wnt antagonists, either of synthetic or natural origin. However, an inverse gradient of Wnt/β-catenin/TCF7L2 signalling activity during CRC progression has been suggested, with early stage and metastatic tumours displaying high and low Wnt signalling activities, respectively, which lead us to revisit the "just-right" signalling model. This may pinpoint the use of Wnt signalling agonists instead of antagonists for treatment of metastatic stages, in a context-dependent fashion. Moreover, the poor immunogenicity of these tumours challenges the use of recently emerged immunotherapies. This chapter makes a journey about CMS2 tumour characterization, their conventional treatment, and how modulation of Wnt signalling or immune response may be applied to CRC therapy. It describes the newest findings in this field and indicates where more research is required.

Polymethoxyflavones prevent benzo[a]pyrene/dextran sodium sulfate-induced colorectal carcinogenesis through modulating xenobiotic metabolism and ameliorate autophagic defect in ICR mice

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental carcinogenic pollutants and they have become an important issue in food contamination. Dietary intake of PAHs has been recognized as a major route of human exposure. However, the mechanisms behind dietary PAH-induced colorectal cancer (CRC) remain unclear. Several studies have shown that polymethoxyflavones (PMFs) are effective in preventing carcinogen-induced CRC or colitis. In this study, we investigated the preventive effect of PMFs on benzo[a]pyrene/dextran sulfate sodium (BaP/DSS)-induced colorectal tumorigenesis in ICR mice. We found that PMFs significantly prevented BaP/DSS-induced colorectal tumor formation. BaP mutagenic metabolite and DNA adducts were found to be reduced in colonic tissue in the PMFs-treated groups through the modulation of BaP metabolism. At the molecular level, the results of RNA-sequencing indicated that PMFs ameliorated BaP/DSS-induced abnormal molecular mechanism change including activated inflammation, downregulated anti-oxidation targets, and induced metastasis genes. The autophagic defect caused by BaP/DSS-induced tumorigenesis was improved by pretreatment with PMFs. We found BaP/DSS-induced CRC may be a Wnt/β-catenin independent process. Additionally, consumption of PMFs extracts also altered the composition of gut microbiota and made it similar to that in the control group by increasing butyrate-producing probiotics and decreasing CRC-related bacteria. BaP in combination with DSS significantly induced colorectal tumorigenesis through induced DNA adduct formation, abnormal gene expression, and imbalanced gut microbiota composition. PMFs were a powerful preventive agent that suppressed BaP/DSS-induced CRC via modulating multiple pathways as well as ameliorating autophagic defect. These results demonstrated for the first time the chemopreventive efficacy and comprehensive mechanisms of dietary PMFs for preventing BaP/DSS-induced colorectal carcinogenesis.

Anti-inflammatory and anticancer effects of flavonol glycosides from Diplotaxis harra through GSK3β regulation in intestinal cells

CONTEXT AND OBJECTIVE

Diplotaxis harra (Forssk.) Boiss. (Brassicaceae) is traditionally used as an antidiabetic, anti-inflammatory or anticancer agent. In these pathologies, the glycogen synthase kinase 3 β (GSK3β) is overactivated and represents an interesting therapeutic target. Several flavonoids can inhibit GSK3β and the purpose of this study was to search for the compounds in Diplotaxis harra which are able to modulate GSK3β.

MATERIALS AND METHODS

Methanol extracts from D. harra flowers were prepared and the bio-guided fractionation of their active compounds was performed using inflammatory [protease-activated receptor 2 (PAR₂)-stimulated IEC6 cells] and cancer (human Caco-2 cell line) intestinal cells. 50-100 μg/mL of fractions or compounds purified by HPLC were incubated with cells whose inhibited form of GSK3β (Pser9 GSK3β) and survival were analyzed by Western blot at 1 h and colorimetric assay at 24 h, respectively. LC-UV-MS profiles and MS-MS spectra were used for the characterization of extracts and flavonoids-enriched fractions, and the identification of pure flavonoids was achieved by MS and NMR analysis.

RESULTS

The methanol extract from D. harra flowers and its flavonoid-enriched fraction inhibit GSK3β in PAR₂-stimulated IEC6 cells. GSK3β inhibition by the flavonoid-enriched D. harra fraction was dependent on PKC activation. The flavonoid-enriched D. harra fraction and its purified compound isorhamnetin-3,7-di-O-glucoside induced a 20% decrease of PAR₂-stimulated IEC6 and Caco-2 cell survival. Importantly, normal cells (non-stimulated IEC6 cells) were spared by these treatments.

CONCLUSION

This work indicates that flavonoids from D. harra display cytotoxic activity against inflammatory and cancer intestinal cells which could depend on GSK3β inhibition.

3'-Hydroxypterostilbene Suppresses Colitis-Associated Tumorigenesis by Inhibition of IL-6/STAT3 Signaling in Mice

3'-Hydroxypterostilbene (trans-3,5-dimethoxy-3',4'-hydroxystilbene) presents in Sphaerophysa salsula, Pterocarpus marsupium, and honey bee propolis and has been reported to exhibit several biological activities. Herein, we aimed to explore the chemopreventive effects of dietary 3'-hydroxypterostilbene and underlying molecular mechanisms on colitis-associated cancer using the azoxymethane (AOM)/dextran sodium sulfate (DSS) model. 3'-Hydroxypterostilbene administration effectively ameliorated the colon shortening and number of tumors in AOM/DSS-treated mice (3.2 ± 1.2 of the high-dose treatment versus 13.8 ± 5.3 of the AOM/DSS group, p < 0.05). Molecular analysis exhibited the anti-inflammatory activity of 3'-hydroxypterostilbene by a significant decrease in the levels of inducible nitric oxide synthase, cyclooxygenase-2, and interleukin-6 (IL-6) (p < 0.05). Moreover, dietary 3'-hydroxypterostilbene also significantly diminished IL-6/signal transducer and activator of transcription signaling and restored colonic suppressor of cytokine signaling 3 levels in the colonic tissue of mice (p < 0.05). Collectively, these results demonstrated for the first time the in vivo chemopreventive efficacy and molecular mechanisms of dietary 3'-hydroxypterostilbene against colitis-associated colonic tumorigenesis.

Bioaccessibility, bioavailability, and anti-inflammatory effects of anthocyanins from purple root vegetables using mono- and co-culture cell models

SCOPE

Immune-inflammatory signaling and metabolic effects are the main pillars for bioactivity of anthocyanins derived from highly pigmented root vegetables. This study aims to assess the bioaccessibility and bioavailability of purple carrot and potato derived anthocyanins and the molecular mechanisms of their ability to ameliorate cellular inflammation in a mono- and co-culture cell models.

METHODS AND RESULTS

An in vitro gastrointestinal model was used and demonstrated bioaccessibility of 44.62 and 71.8% for anthocyanins of purple carrot and potato, respectively. These accessible anthocyanins significantly inhibited cellular inflammation in Caco-2 cells. Intact cyanidinglycoside or petunidinglycoside (respectively from carrots and potatoes) were transported across a transmembrane cell model and detected by LC-MS/MS. Computational docking and glucose uptake analyses suggested uptake of anthocyanins was mediated by hexose transporters. Subsequent experiment using an inflamed Caco-2 BBe1/THP-1 co-culture cell model showed these transported anthocyanins inhibited IL-8 and TNF-α secretion,and expression of pro-inflammatory cytokines by blocking NF-κB, and MAPK mediated inflammatory cellular signaling cascades, but with varying degrees due to structural features.

CONCLUSION

Anthocyanins from purple carrots and potatoes possess a promising anti-inflammatory effect in model gut system. They can be absorbed and act differently but are in general beneficial for inflammation-mediated diseases.

BRM270, a Compound from Natural Plant Extracts, Inhibits Glioblastoma Stem Cell Properties and Glioblastoma Recurrence

Glioblastoma multiforme (GBM) is one of the most aggressive and lethal human brain tumors, and the median survival of patients with GBM is only 14 months. Glioblastoma stem cells (GSCs) are regarded as a main cause of GBM recurrence, because of their self-renewal and drug resistance properties. Therefore, targeting GSCs is an important therapeutic strategy for GBM. In this study, we show the effects of BRM270, a compound from natural plant extracts, on GSCs in vitro and GBM recurrence in vivo. BRM270 induced apoptotic cell death and inhibited cell growth and "stemness" both in vitro and in vivo. Combining BRM270 treatment with concurrent chemoradiotherapy (CCRT) dramatically increased mice survival and tumor growth inhibition. Taken together, our results suggested that BRM270 synergizes with CCRT as a therapeutic agent to target GSCs.

New Insights toward Colorectal Cancer Chemotherapy Using Natural Bioactive Compounds

Combination therapy consists in the simultaneous administration of a conventional chemotherapy drug (or sometimes, a radiotherapy protocol) together with one or more natural bioactives (usually from plant or fungal origin) of small molecular weight. This combination of anticancer drugs may be applied to cell cultures of tumor cells, or to an animal model for a cancer type (or its xenograft), or to a clinical trial in patients. In this review, we summarize current knowledge describing diverse synergistic effects on colorectal cancer cell cultures, animal models, and clinical trials of various natural bioactives (stilbenes, flavonoids, terpenes, curcumin, and other structural families), which may be important with respect to diminish final doses of the chemotherapy drug, although maintaining its biological effect. This is important as these approaches may help reduce side effects in patients under conventional chemotherapy. Also, these molecules may exerts their synergistic effects via different cell cycle pathways, including different ones to those responsible of resistance phenotypes: transcription factors, membrane receptors, adhesion and structural molecules, cell cycle regulatory components, and apoptosis pathways.

Inhibition of NF-κB and metastasis in irinotecan (CPT-11)-resistant LoVo colon cancer cells by thymoquinone via JNK and p38

Clinically used chemotherapeutics can effectively eliminate most tumor cells. However, they cause unwanted side effects and result in chemoresistance. To overcome such problems, phytochemicals are now used to treat cancers by means of targeted therapy. Thymoquinone (TQ) is used to treat different cancers (including colon cancer) and is an NF-κB inhibitor. Irinotecan resistant (CPT-11-R) LoVo colon cancer cell line was previous constructed by step-wise CPT-11 challenges to un-treated parental LoVo cells and expresses EGFR/IKKα/β/NF-κB pathway. TQ resulted in reduced total and phosphorylation of IKKα/β and NF-κB and decreased metastasis in CPT-11-R cells. TQ not only reduced activity of ERK1/2 and PI3K but also activated JNK and p38. Furthermore, TQ was also found to suppress metastasis through activation of JNK and p38. Therefore, TQ suppressed metastasis through NF-κB inhibition and activation of JNK and p38 in CPT-11-R LoVo colon cancer cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 669-678, 2017.

The Gastrointestinal Tract as a Key Target Organ for the Health-Promoting Effects of Dietary Proanthocyanidins

Proanthocyanidins (PACs) are polymers of flavan-3-ols abundant in many vegetable foods and beverages widely consumed in the human diet. There is increasing evidence supporting the beneficial impact of dietary PACs in the prevention and nutritional management of non-communicable chronic diseases. It is considered that PACs with a degree of polymerization >3 remain unabsorbed in the gastrointestinal (GI) tract and accumulate in the colonic lumen. Accordingly, the GI tract may be considered as a key organ for the healthy-promoting effects of dietary PACs. PACs form non-specific complexes with salivary proteins in mouth, originating the sensation of astringency, and with dietary proteins, pancreatic enzymes, and nutrient transporters in the intestinal lumen, decreasing the digestion and absorption of carbohydrates, proteins, and lipids. They also exert antimicrobial activities, interfering with cariogenic or ulcerogenic pathogens in the mouth (Streptococcus mutans) and stomach (Helicobacter pylori), respectively. Through their antioxidant and antiinflammatory properties, PACs decrease inflammatory processes in animal model of gastric and colonic inflammation. Interestingly, they exert prebiotic activities, stimulating the growth of Lactobacillus spp. and Bifidobacterium spp. as well as some butyrate-producing bacteria in the colon. Finally, PACs are also metabolized by the gut microbiota, producing metabolites, mainly aromatic acids and valerolactones, which accumulate in the colon and/or are absorbed into the bloodstream. Accordingly, these compounds could display biological activities on the colonic epithelium or in extra-intestinal tissues and, therefore, contribute to part of the beneficial effects of dietary PACs.

Effects of Prunus mume Sieb. et Zucc. extract and its biopolymer encapsulation on a mouse model of colitis

BACKGROUND

Prunus mume suppresses various diseases caused by inflammation response and exhibits antioxidant and free radical-scavenging activities. Therefore this study determined the effect of an aqueous P. mume (PM) extract in a mouse colitis model and investigated the value of biopolymer encapsulation, facilitating targeted delivery to the colon. Colitis was induced by administration of 30 g kg^-1 dextran sulfate sodium to male BALB/c mice for 7 days prior to treatment with vehicle, 50 mg kg^-1 PM extract or biopolymer-encapsulated PM extract, or 50 mg kg^-1 sulfasalazine.

RESULTS

Histological examination of the colon in BALB/c mice showed epithelial destruction and mucosal infiltration of inflammatory cells. These changes were attenuated in PM-treated mice, which had lower levels of inflammatory cytokines, cyclooxygenase 2 and immunoglobulins (IgA, IgM and IgE) compared with the vehicle-treated colitis group. The PM extract showed concentration-dependent radical scavenging and superoxide dismutase-like antioxidant activities.

CONCLUSION

These results indicated that the effects of the PM extract on colitis were not influenced by biopolymer encapsulation and that this PM extract could be a potential therapeutic agent for inflammatory bowel disease. © 2016 Society of Chemical Industry.

Chemopreventive effect of natural dietary compounds on xenobiotic-induced toxicity

Contaminants (or pollutants) that affect human health have become an important issue, spawning a myriad of studies on how to prevent harmful contaminant-induced effects. Recently, a variety of biological functions of natural dietary compounds derived from consumed foods and plants have been demonstrated in a number of studies. Natural dietary compounds exhibited several beneficial effects for the prevention of disease and the inhibition of chemically-induced carcinogenesis. Contaminant-induced toxicity and carcinogenesis are mostly attributed to the mutagenic activity of reactive metabolites and the disruption of normal biological functions. Therefore, the metabolic regulation of hazardous chemicals is key to reducing contaminant-induced adverse health effects. Moreover, promoting contaminant excretion from the body through Phase I and II metabolizing enzymes is also a useful strategy for reducing contaminant-induced toxicity. This review focuses on summarizing the natural dietary compounds derived from common dietary foods and plants and their possible mechanisms of action in the prevention/suppression of contaminant-induced toxicity.

Anti-Oxidant, Pro-Oxidant and Anti-Inflammatory Effects of Unpolished Rice Relevant to Colorectal Cancer

Colorectal cancer (CRC) is a major worldwide health problem owing to its high prevalence and mortality rates. Carcinogenesis in the colon is a multistage and multifactorial process. An imbalance between free radical exposure and anti-oxidant defense systems may leads to oxidative stress and attack of macromolecules which can alter signal transduction pathways and gene expression. Consequently, oxidative damage can lead to cellular dysfunction and contribute to pathophysiological processes in a variety of diseases including CRC. One factor tightly associated with CRC is chronic inflammation, which can be present from the earliest stage of tumor onset. Unpolished rice is an attractive chemoprevention in CRC due to their anti-oxidant and anti-inflammatory activities. The aim of this paper is to review evidence linking oxidative stress and inflammation to CRC and to provide essential background information for understanding future research on oxidative stress and inflammation on CRC. Mechanisms of action of unpolished rice in CRC carcinogenesis are also discussed.

Comparative effectiveness of chemopreventive interventions for colorectal cancer: protocol for a systematic review and network meta-analysis of randomised controlled trials

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide and is associated with substantial socioeconomic burden. Despite considerable research, including numerous randomised controlled trials (RCTs) and systematic reviews assessed the effect of various chemopreventive interventions for CRC, there remains uncertainty regarding the comparative effectiveness of these agents. No network meta-analytic study has been published to evaluate the efficacies of these agents for CRC. Therefore, the aim of this study is to summarise the direct and indirect evidence for these interventions to prevent CRC in average-high risk individuals, and to rank these agents for practical consideration.

METHODS

We will acquire eligible studies through a systematic search of MEDLINE, EMBASE, the Cochrane Central Registry of Controlled Trials, CINAHL plus, IPA and clinicaltrials.gov website. The Cochrane Risk of Bias Tool will be used to assess the quality of included studies. The primary outcomes are the incidence of CRC, the incidence/recurrence of any adenoma or change in polyp burden (number or size). Quantitative synthesis or meta-analysis will be considered. We will also construct a network meta-analysis (NMA) to improve precision of the comparisons among chemo-preventive interventions by combining direct and indirect evidence. The probability of each treatment being the best and/or safest, the number-needed-to-treat [NNT; 95% credible interval (CrIs)], and the number-needed-to-harm (NNH; 95% CrIs) will be calculated to provide measures of treatment efficacy. The GRADE approach will be used to rate the quality of evidence of estimates derived from NMA.

RESULTS

This protocol has been registered (registration number: CRD42015025849) with the PROSPERO (International Prospective Register of Systematic Reviews). The procedures of this systematic review and NMA will be conducted in accordance with the PRISMA-compliant guideline. The results of this systematic review and NMA will be submitted to a peer-reviewed journal for publication.

CONCLUSIONS

To the best of our knowledge, this study will be the first NMA to identify the comparative effectiveness of interventions for the prevention of CRC. The results of our study will update evidence for chemoprevention of CRC, identify key areas for future research, and provide a framework for conducting large systematic reviews involving indirect comparisons.

Targeting CRMP-4 by lentivirus-mediated RNA interference inhibits SW480 cell proliferation and colorectal cancer growth

The aim of the present study was to investigate the expression level of collapsin response mediator protein 4 (CRMP-4) in human colorectal cancer (CRC) tissue and to evauluate its impact on SW480 cell proliferation, in addition to tumor growth in a mouse xenograft model. Clinical CRC tissue samples were collected to detect the CRMP-4 protein expression levels using western blot and immunohistochemistry analyses. A specific small interfering RNA sequence targeting the CRMP-4 gene (DPYSL3) was constructed and transfected into an SW480 cell line using a lentivirus vector to obtain a stable cell line with low expression of CRMP-4. The effectiveness of the interference was evaluated using western blot and reverse transcription-quantitative polymerase chain reaction, and the cell proliferation was determined using MTT and BrdU colorimetric methods. Tumor growth was assessed by subcutaneously inoculating the constructed cells into BALB/c nude mice. The protein expression levels of CRMP-4 were markedly increased in colon tumor tissue of the human samples. The proliferation of SW480 cells and the tumor growth rate in nude mice of the si-CPMR-4 group were evidently depressed compared with the si-scramble group. Thus, the present results suggest that CRMP-4 may be involved in the pathogenesis of CRC.

Early detection of high oxidative activity in patients with adenomatous intestinal polyps and colorectal adenocarcinoma: myeloperoxidase and oxidized low-density lipoprotein in serum as new markers of oxidative stress in colorectal cancer

OBJECTIVES

To detect whether signs of oxidative stress appear at early stages of colorectal adenocarcinoma (CRC), particularly in the polyp stage. We also aimed to evaluate the specific entities myeloperoxidase (MPO) and oxidized low-density lipoprotein (oxLDL) as novel markers of oxidation in the plasma of patients with CRC and to study the relationship between oxidative status in plasma and patient survival.

METHODS

We assayed serum or plasma specimens from healthy control subjects (n = 14), from patients with intestinal polyps (n = 39), and from patients with CRC (n = 128) to calculate the modified oxidative balance score (MOBS) using several serum markers (β-carotene, lycopene, vitamin A, vitamin E, MPO, and oxLDL). We also assayed the levels of C-reactive protein (CRP) and obtained lipid profiles. Finally, we studied the survival of patients in relationship to oxidative status (antioxidants and pro-oxidants) and inflammation markers, and added theses data to the lipid profile for each patient.

RESULTS

Oxidative stress levels increased as disease stage advanced. This increase was detected early in the polyp stage, before polyps progressed to cancer, and could be measured by the increase of such new markers as MPO and oxLDL, the decrease in antioxidants, and the MOBS value. Higher levels of oxidation correlated with lower survival.

CONCLUSION

The oxidation process, which can cause mutations leading to CRC, begins development in the polyp stage. This process may be detected early by monitoring serum markers such as MPO and oxLDL.

Plum polyphenols inhibit colorectal aberrant crypt foci formation in rats: potential role of the miR-143/protein kinase B/mammalian target of rapamycin axis

The nutritional prevention of aberrant crypt foci by polyphenols may be a crucial step to dietary cancer prevention. The objective of this study was to determine the underlying mechanisms that contribute to the anti-inflammatory and antitumorigenic properties of plum (Prunus salicina L.) polyphenols, including chlorogenic acid and neochlorogenic acid, in azoxymethane (AOM)-treated rats. The hypothesis was that plum polyphenolics suppress AOM-induced aberrant crypt foci formation through alterations in the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway and relative micro-RNA expressions. Sprague-Dawley rats (n=10/group) received plum beverage (1346mg gallic acid equivalents/L) or a control beverage ad libitum for 10 weeks with subcutaneous injections of AOM (15mg/kg) at weeks 2 and 3. Results show that the consumption of the plum beverage decreased the number of dysplastic aberrant crypt foci by 48% (P<.05) and lowered proliferation of mucosal cells by 24% (P<.05). The plum beverage decreased the activity of glutathione peroxidase, superoxide dismutase, and catalase in mucosal scrapings, as well as the superoxide dismutase activity in serum. The results were accompanied by a down-regulation of proinflammatory enzymes nuclear factor κB, nitric oxide synthase, cyclooxygenase-2, and vascular cell adhesion molecule 1 messenger RNA. Plum inhibited the expression of AKT and mTOR messenger RNA, phosphorylated AKT, mTOR, and hypoxia-inducible factor-1α protein levels, and the ratio of the phosphorylated/total protein expression of mTOR. Also, the plum beverage increased the expression of miR-143, which is involved in the regulation of AKT. These results suggest that plum polyphenols may exhibit a chemopreventive potential against colon carcinogenesis by impacting the AKT/mTOR pathway and miR-143.

Effect of Cocoa and Its Flavonoids on Biomarkers of Inflammation: Studies of Cell Culture, Animals and Humans

Chronic inflammation has been identified as a necessary step to mediate atherosclerosis and cardiovascular disease and as a relevant stage in the onset and progression of several types of cancer. Considerable attention has recently been focused on the identification of dietary bioactive compounds with anti-inflammatory activities as an alternative natural source for prevention of inflammation-associated diseases. The remarkable capacity of cocoa flavanols as antioxidants, as well as to modulate signaling pathways involved in cellular processes, such as inflammation, metabolism and proliferation, has encouraged research on this type of polyphenols as useful bioactive compounds for nutritional prevention of cardiovascular disease and cancer. Data from numerous studies suggest that cocoa and cocoa-derived flavanols can effectively modify the inflammatory process, and thus potentially provide a benefit to individuals with elevated risk factors for atherosclerosis/cardiovascular pathology and cancer. The present overview will focus on the most recent findings about the effects of cocoa, its main constituents and cocoa derivatives on selected biomarkers of the inflammatory process in cell culture, animal models and human cohorts.

Hepatoprotective effects of polymethoxyflavones against acute and chronic carbon tetrachloride intoxication

In the present study, we explore the protective effects of Citrus aurantium L. extract (CAE) against acute and chronic CCl4-induced hepatotoxicity. The quantitative analysis of CAE was performed using HPLC-UV to determine the nobiletin content was approximately 27%. For the acute model, the male ICR mice were orally treated with water, silymarin (positive control, 200 mg/kg) and CAE (50 and 200 mg/kg) for 3 days prior to CCl4 (1 mL/kg, 50% v/v in olive oil) IP injection. For the chronic model (n = 6/group), the mice were treated with each treatment for 28 consecutive days and CCl4 (1 mL/kg, 20%) was injected twice a week. In both the acute and chronic models, the CCl4 alone treated group showed histopathologic alterations with a significantly increase in serum hepatic enzyme levels together with a disrupted anti-oxidative status. In contrast, the CAE treatments restored pathologic alterations and recovered the oxidative status by enhancing antioxidant enzymes and reducing lipid peroxidation levels. Furthermore, CAE enhanced nuclear factor E2-related factor 2 (Nrf2) and its related cytoprotective signals, including NAD(P)H quinone oxidoreductase 1, UDP-glucuronosyltransferase, and γ-glutamylcysteine synthetase. Taken together, the present study demonstrates that CAE exerts a protective effect against CCl4-induced hepatotoxicity with its anti-oxidant, anti-inflammatory, and anti-apoptotic activity.

Preventive Effects of Cocoa and Cocoa Antioxidants in Colon Cancer

Colorectal cancer is one of the main causes of cancer-related mortality in the developed world. Carcinogenesis is a multistage process conventionally defined by the initiation, promotion and progression stages. Natural polyphenolic compounds can act as highly effective antioxidant and chemo-preventive agents able to interfere at the three stages of cancer. Cocoa has been demonstrated to counteract oxidative stress and to have a potential capacity to interact with multiple carcinogenic pathways involved in inflammation, proliferation and apoptosis of initiated and malignant cells. Therefore, restriction of oxidative stress and/or prevention or delayed progression of cancer stages by cocoa antioxidant compounds has gained interest as an effective approach in colorectal cancer prevention. In this review, we look over different in vitro and in vivo studies that have identified potential targets and mechanisms whereby cocoa and their flavonoids could interfere with colonic cancer. In addition, evidence from human studies is also illustrated.

Polyphenols from pinecones of Pinus koraiensis induce apoptosis in colon cancer cells through the activation of caspase in vitro

The present study reports the antitumor effects of PPP-40 (the purified polyphenols from P. koraiensis pinecones by 40% ethanol) on LOVO cells and revealed its antitumor mechanism, which involved the apoptosis of cells associated with the activation of the caspase pathway.

Molecular docking analysis of known flavonoids as duel COX-2 inhibitors in the context of cancer

Cyclooxygenase-2 (COX-2) catalyzed synthesis of prostaglandin E2 and it associates with tumor growth, infiltration, and metastasis in preclinical experiments. Known inhibitors against COX-2 exhibit toxicity. Therefore, it is of interest to screen natural compounds like flavanoids against COX-2. Molecular docking using 12 known flavanoids against COX-2 by FlexX and of ArgusLab were performed. All compounds showed a favourable binding energy of >-10 KJ/mol in FlexX and > -8 kcal/mol in ArgusLab. However, this data requires in vitro and in vivo verification for further consideration.

Colon Cancer Chemoprevention by Sage Tea Drinking: Decreased DNA Damage and Cell Proliferation

Salvia officinalis and some of its isolated compounds have been found to be preventive of DNA damage and increased proliferation in vitro in colon cells. In the present study, we used the azoxymethane model to test effects of S. officinalis on colon cancer prevention in vivo. The results showed that sage treatment reduced the number of ACF formed only if administered before azoxymethane injection, demonstrating that sage tea drinking has a chemopreventive effect on colorectal cancer. A decrease in the proliferation marker Ki67 and in H2 O2 -induced and azoxymethane-induced DNA damage to colonocytes and lymphocytes were found with sage treatment. This confirms in vivo the chemopreventive effects of S. officinalis. Taken together, our results show that sage treatment prevented initiation phases of colon carcinogenesis, an effect due, at least in part, to DNA protection, and reduced proliferation rates of colon epithelial cell that prevent mutations and their fixation through cell replication. These chemopreventive effects of S. officinalis on colon cancer add to the many health benefits attributed to sage and encourage its consumption.

Carvacrol inhibits proliferation and induces apoptosis in human colon cancer cells

Colon cancer is one of the most common malignancies worldwide and has a high mortality rate. Carvacrol is a major component of oregano and thyme essential oils and shows antitumor properties. Here, we investigated the effects of carvacrol on the proliferation and apoptosis of two human colon cancer cell lines, HCT116 and LoVo, and studied the molecular mechanisms of its antitumor properties. We found that carvacrol inhibited the proliferation and migration of the two colon cancer cell lines in a concentration-dependent manner. Cell invasion was suppressed after carvacrol treatment by decreasing the expression of matrix metalloprotease-2 (MMP-2) and MMP-9. Carvacrol treatment also caused cell cycle arrest in the G2/M phase and decreased cyclin B1 expression. Finally, carvacrol induced cell apoptosis in a dose-dependent manner. At the molecular level, carvacrol downregulated the expression of Bcl-2 and induced the phosphorylation of the extracellular-regulated protein kinase and protein kinase B (p-Akt). In parallel, carvacrol upregulated the expression of Bax and c-Jun N-terminal kinase. These results indicate that carvacrol might induce apoptosis in colon cancer cells through the mitochondrial apoptotic pathway and the MAPK and PI3K/Akt signaling pathways. Together, our results suggest that carvacrol may have therapeutic potential for the prevention and treatment of colon cancer.

Onset of the lymphocytic infiltration and hyperplasia preceding the proliferation in F1 mouse lungs from the N-ethyl-N-nitrosourea exposed mothers: Prevention during the lactation period by inositol hexaphosphate

Maternal exposure to a carcinogen is associated with increased risk of different cancers in the offspring. The foetus is highly sensitive to carcinogens and this contributes to the foetal basis of the onset of disease. The better understanding of the molecular mechanisms involved in the early stage of lung tumourigenesis in the offspring is needed for the newer preventive strategies. We evaluated the effects of N-ethyl-N-nitrosourea (ENU) given on the 17th day of gestation and antitumour agent inositol hexaphosphate (IP6) to the mothers at the early stage of lung tumourigenesis in F1 mice. There was no treatment related effects on the litter size or body weight of the F1 mice at the PND12 or 24. Analysis of PCNA, NF-κB (p50), IL-6, COX-2, pSTAT3, STAT3, caspase-3, caspase-9, PARP, Akt signalling and downstream cyclin D1 along with miR-155, suggested the modulation of proliferation, inflammation and apoptosis at PND12 and 24. IP6 administration to the predisposed mothers prevented the proliferation, inflammation and enhanced apoptosis in F1 lung as showed by a reduction in PCNA, NF-κB (p50), IL-6, COX-2, pSTAT3, STAT3, miR-155 and increase in caspases, cleavage of poly (ADP-ribose) polymerase. IP6 administration also inhibited the activation of Akt and cyclin D1. Our study shows that tumourigenic changes take place in the lungs of the F1 generation from the carcinogen predisposed mothers even before the onset of tumours and the simultaneous intake of chemopreventive agent during the gestation or lactation period could prevent the lymphocytic infiltration and hyperplasia preceding the tumourigenesis.

Thymoquinone induces caspase-independent, autophagic cell death in CPT-11-resistant lovo colon cancer via mitochondrial dysfunction and activation of JNK and p38

Chemotherapy causes unwanted side effects and chemoresistance, limiting its effectiveness. Therefore, phytochemicals are now used as alternative treatments. Thymoquinone (TQ) is used to treat different cancers, including colon cancer. The irinotecan-resistant (CPT-11-R) LoVo colon cancer cell line was previously constructed by stepwise CPT-11 challenges to untreated parental LoVo cells. TQ dose-dependently increased the total cell death index and activated apoptosis at 2 μM, which then diminished at increasing doses. The possibility of autophagic cell death was then investigated. TQ caused mitochondrial outer membrane permeability (MOMP) and activated autophagic cell death. JNK and p38 inhibitors (SP600125 and SB203580, respectively) reversed TQ autophagic cell death. TQ was also found to activate apoptosis before autophagy, and the direction of cell death was switched toward autophagic cell death at initiation of autophagosome formation. Therefore, TQ resulted in caspase-independent, autophagic cell death via MOMP and activation of JNK and p38 in CPT-11-R LoVo colon cancer cells.

Influence of processing parameters on morphology of polymethoxyflavone in emulsions

Polymethoxyflavones (PMFs) are groups of compounds isolated from citrus peels that have been documented with wide arrays of health-promoting bioactivities. Because of their hydrophobic structure and high melting point, crystallized PMFs usually have poor systemic bioavailability when consumed orally. To improve the oral efficiency of PMFs, a viscoelastic emulsion system was formulated. Because of the crystalline nature, the inclusion of PMFs into the emulsion system faces great challenges in having sufficient loading capacity and stabilities. In this study, the process of optimizing the quality of emulsion-based formulation intended for PMF oral delivery was systematically studied. With alteration of the PMF loading concentration, processing temperature, and pressure, the emulsion with the desired droplet and crystal size can be effectively fabricated. Moreover, storage temperatures significantly influenced the stability of the crystal-containing emulsion system. The results from this study are a good illustration of system optimization and serve as a great reference for future formulation design of other hydrophobic crystalline compounds.

PAC exhibits potent anti-colon cancer properties through targeting cyclin D1 and suppressing epithelial-to-mesenchymal transition

Colorectal cancer (CRC) is a major cause of cancer morbidity and mortality worldwide. Although response rates and overall survival have been improved in recent years, resistance to multiple drug combinations is inevitable. Therefore, the development of more efficient drugs, with fewer side effects is urgently needed. To this end, we have investigated in the present report the effect of PAC, a novel cucumin analogue, on CRC cells both in vitro and in vivo. We have shown that PAC induces apoptosis, mainly via the internal mitochondrial route, and inhibits cell proliferation through delaying the cell cycle at G2/M phase. Interestingly, the pro-apoptotic effect was mediated through STAT3-dependent down-regulation of cyclin D1 and its downstream target survivin. Indeed, change in the expression level of cyclin D1 modulated the expression of survivin and the response of CRC cells to PAC. Furthermore, using the ChIP assay, we have shown PAC-dependent reduction in the binding of STAT3 to the cyclin D1 promoter in vivo. Additionally, PAC suppressed the epithelial-to-mesenchymal process through down-regulating the mesenchymal markers (N-cadherin, vimentin and Twist1) and inhibiting the invasion/migration abilities of the CRC cells via repressing the pro-migration/invasion protein kinases AKT and ERK1/2. In addition, PAC inhibited tumor growth and repressed the JAK2/STAT3, AKT/mTOR and MEK/ERK pathways as well as their common downstream effectors cyclin D1 and survivin in humanized CRC xenografts. Collectively, these results indicate that PAC has potent anti-CRC effects, and therefore could constitute an effective alternative chemotherapeutic agent, which may consolidate the adjuvant treatment of colon cancer.

γ-Glutamyl cysteine and γ-glutamyl valine inhibit TNF-α signaling in intestinal epithelial cells and reduce inflammation in a mouse model of colitis via allosteric activation of the calcium-sensing receptor

BACKGROUND

The extracellular calcium-sensing receptor (CaSR) is distributed throughout the gastrointestinal tract, and its activation has been shown to promote intestinal homeostasis, suggesting that CaSR may be a promising target for novel therapies to prevent chronic intestinal inflammation such as inflammatory bowel disease (IBD). The γ-glutamyl dipeptides γ-glutamyl cysteine (γ-EC) and γ-glutamyl valine (γ-EV) are dietary flavor enhancing compounds, and have been shown to activate CaSR via allosteric ligand binding. The aim of this study was to examine the anti-inflammatory effects of γ-EC and γ-EV in vitro in intestinal epithelial cells and in a mouse model of intestinal inflammation.

RESULTS

In vitro, treatment of Caco-2 cells with γ-EC and γ-EV resulted in the CaSR-mediated reduction of TNF-α-stimulated pro-inflammatory cytokines and chemokines including IL-8, IL-6, and IL-1β, and inhibited phosphorylation of JNK and IκBα, while increasing expression of IL-10. In vivo, using a mouse model of dextran sodium sulfate (DSS)-induced colitis, γ-EC and γ-EV treatment ameliorated DSS-induced clinical signs, weight loss, colon shortening and histological damage. Moreover, γ-EC and γ-EV reduced the expression of TNF-α, IL-6, INF-γ, IL-1β, and IL-17, and increased the expression of IL-10 in the colon, in a CaSR-dependent manner. The CaSR-mediated anti-inflammatory effects of γ-EC were abrogated in β-arrestin2 knock-down Caco-2 cells, and involvement of β-arrestin2 was found to inhibit TNF-α-dependent signaling via cross-talk with the TNF-α receptor (TNFR).

CONCLUSIONS

Thus CaSR activation by γ-EC and γ-EV can aid in maintaining intestinal homeostasis and reducing inflammation in chronic inflammatory conditions such as IBD.

The ellagic acid-derived gut microbiota metabolite, urolithin A, potentiates the anticancer effects of 5-fluorouracil chemotherapy on human colon cancer cells

The ellagic acid-derived gut microbiota metabolite, urolithin A, at concentrations achievable in the human colorectum, enhances the anticancer effects of 5-FU-chemotherapy on three different colon cancer cells.

Apple polysaccharide reduces NF-Kb mediated colitis-associated colon carcinogenesis

Nuclear factor-kappa B (NF-κB) is an important molecule in mediating inflammatory colitis, which can lead to colorectal cancer (CRC). The aim of this study was to evaluate the chemopreventive efficacy of apple polysaccharide extract (AP) in inhibiting NF-κB-mediated inflammation pathways in CRC. We evaluated AP in vitro in HT-29 and SW620 human CRC cells. We also used the azoxymethane and dextran sodium sulphate (AOM/DSS) model to induce colon carcinogenesis in vivo. The chemoprotective effects of AP were assessed using Western blot, immunofluorescence assay, real-time PCR, electrophoretic mobility shift assay, and flow cytometry. AP reduced AOM/DSS-associated toxicities, prevented carcinogenesis, and decreased the expression of TLR4, MD2, MyD88, TRAM, TRIF-related adapter molecule, interferon-β, tumor necrosis factor-α, and interleukin-6. The protective effects of AP may be related to the inhibition of TLR4/MD2-mediated signaling, including MyD88 and TRIF, as well as the inhibition of NF-κB-mediated inflammatory signaling pathways. Therefore, AP could be used in combination therapy for the prevention of colitis-associated colon cancer.

Differential control of growth, apoptotic activity and gene expression in human colon cancer cells by extracts derived from medicinal herbs, Rhazya stricta and Zingiber officinale and their combination

AIM

To investigate the effects of extracts from Rhazya stricta (R. stricta) and Zingiber officinale (Z. officinale) on human colorectal cancer cells.

METHODS

Human colorectal cancer cells (HCT116) were subjected to increasing doses of crude alkaloid extracts from R. stricta (CAERS) and crude flavonoid extracts from Z. officinale (CFEZO). Cells were then harvested after 24, 48 or 72 h and cell viability was examined by trypan blue exclusion dye test; clonogenicity and soft agar colony-forming assays were also carried out. Nuclear stain (Hoechst 33342), acridine orange/ethidium bromide double staining, agarose gel electrophoresis and comet assays were performed to assess pro-apoptotic potentiality of the extracts. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR), using gene-specific primers and Western blot analyses were performed to assess the impact of CAERS and CFEZO on the expression levels of key regulatory proteins in HCT116 cells.

RESULTS

Treatment with a combination of CAERS and CFEZO synergistically suppressed the proliferation, colony formation and anchorage-independent growth of HCT116 cells. Calculated IC50, after 24, 48 and 72 h, were 70, 90 and 130 μg/mL for CAERS, 65, 85 and 120 μg/mL for CFEZO and 20, 25 and 45 μg/mL for both agents, respectively. CAERS- and CFEZO-treated cells exhibited morphologic and biochemical features of apoptotic cell death. The induction of apoptosis was associated with the release of mitochondrial cytochrome c, an increase in the Bax/Bcl-2 ratio, activation of caspases 3 and 9 and cleavage of poly ADP-ribose polymerase. CAERS and CFEZO treatments downregulated expression levels of anti-apoptotic proteins including Bcl-2, Bcl-X, Mcl-1, survivin and XIAP, and upregulated expression levels of proapoptotic proteins such as Bad and Noxa. CAERS and CFEZO treatments elevated expression levels of the oncosuppressor proteins, p53, p21 and p27, and reduced levels of the oncoproteins, cyclin D1, cyclin/cyclin-dependent kinase-4 and c-Myc.

CONCLUSION

These data suggest that a combination of CAERS and CFEZO is a promising treatment for the prevention of colon cancer.

Reducing mortality from colorectal cancer: screening versus primary prevention

SUMMARY 

Screening reduces mortality from colorectal cancer but, like breast and prostate cancer screening, does not significantly prolong life expectancy. It is cost effective though, as polyp removal prevents cancer development and its associated cost and morbidity. Given the lack of impact of screening on overall life expectancy, prevention of colorectal cancer by lifestyle adjustment, particularly dietary, should still be considered as an alternative strategy. Avoidance of excessive calories and increased fiber intake would probably reduce risk not only for colorectal cancer but also for cardiovascular and cerebrovascular disease and substantially reduce all-cause mortality. We need better knowledge though of how specific dietary components impact on colon cancer risk and for this we probably need better understanding of the role of bacteria.

The effects of selected drugs and dietary compounds on proliferation and apoptosis in colorectal carcinoma

Like many malignancies, the development of colorectal carcinoma (CRC) can be considered as an imbalance between the compromised process of programmed cell death (apoptosis) and excessive, uncontrolled proliferation. Several mutations and epigenetic alterations are acquired during colorectal carcinogenesis. These are responsible for the cell cycle regulation, cellular sensitivity to pro- and antiapoptotic factors, cell proliferation, angiogenesis, invasiveness, as well as metastatic potential. The molecular alterations, along with their morphological expressions, have been recognised in detail, and most of the CRC cases can be attributed to either adenoma-carcinoma or serrated neoplasia pathways: in the first, the antiapoptotic features prevail; while in the second, the proliferative activity is of the utmost importance. The aim of the work is to discuss the influence of selected drugs and dietary compounds on the proliferation and apoptosis in CRC.

Garcinol suppresses inflammation-associated colon carcinogenesis in mice

SCOPE

Garcinol is a polyisoprenylated benzophenone derivative isolated from the fruit rind of Garcinia indica and has exhibited chemopreventive effects on azoxymethane)-induced colonic aberrant crypt foci in mice. In this study, we investigated whether garcinol protects against dextran sulfate sodium (DSS) induced colitis/inflammation and azoxymethane/DSS-induced inflammation-related colon tumorigenesis in male ICR mice. We also aimed to delineate the possible molecular mechanisms responsible for these effects.

METHODS AND RESULTS

Treatment with garcinol prevented shortening of the colon length and the formation of aberrant crypt foci and improved the inflammation score in the mouse colon stimulated by DSS. Moreover, administration of garcinol markedly decreased DSS-induced inducible nitric oxide synthase, cyclooxygenase-2, and proliferating cell nuclear antigen protein expression. The dietary administration of garcinol effectively reduced the tumor size and incidence in the mouse colon. Western blot and immunohistochemical analysis revealed that administration of garcinol significantly downregulated cyclooxygenase-2, cyclin D1, and vascular endothelial growth factor expression via inhibition of the extracellular signal-regulated protein kinase 1/2, phosphatidylinositol 3 kinase/Akt/p70 ribosomal S6 kinase, and Wnt/β-catenin signaling pathways.

CONCLUSION

Our results suggest that garcinol may merit further clinical investigation as a chemoprophylactic food that helps prevent colitis-associated colon cancer.

Epicatechin gallate induces cell death via p53 activation and stimulation of p38 and JNK in human colon cancer SW480 cells

The tea flavonoid epicatechin gallate (ECG) exhibits a wide range of biological activities. In this study, the in vitro anticancer effects of ECG on SW480 colon cancer cell line was investigated by analyzing the cell cycle, apoptosis, key proteins involved in cellular survival/proliferation, namely AKT/phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinases (MAPKs), and the role of p53 in these processes. ECG induced cell cycle arrest at the G0/G1-S phase border associated with the stimulation of p21, p-p53, and p53 and the suppression of cyclins D1 and B1. Exposure of SW480 cells to ECG also led to apoptosis as determined by time-dependent changes in caspase-3 activity, MAPKs [extracellular regulated kinase (ERK), p38, and c-jun amino-terminal kinase (JNK)], p21 and p53 activation, and AKT inhibition. The presence of pifithrin, an inhibitor of p53 function, blocked ECG-induced apoptosis as was manifested by restored cell viability and caspase-3 activity to control values and reestablished the balance among Bcl-2 anti- and proapoptotic protein levels. Interestingly, ECG also inhibited p53 protein and RNA degradation, contributing to the stabilization of p53. In addition, JNK and p38 have been identified as necessary for ECG-induced apoptosis, upon activation by p53. The results suggest that the activation of the p53-p38/JNK cascade is required for ECG-induced cell death in SW480 cells.