beta-Carotene downregulates the steady-state and heregulin-alpha-induced COX-2 pathways in colon cancer cells

Combination of oxaliplatin and β-carotene suppresses colorectal cancer by regulating cell cycle, apoptosis, and cancer stemness in vitro

BACKGROUND/OBJECTIVES

Colorectal cancer (CRC) is the third most common cancer worldwide with a high recurrence rate. Oxaliplatin (OXA) resistance is one of the major reasons hindering CRC therapy. β-Carotene (BC) is a provitamin A and is known to have antioxidant and anticancer effects. However, the combined effect of OXA and BC has not been investigated. Therefore, this study investigated the anticancer effects and mechanism of the combination of OXA and BC on CRC.

MATERIALS/METHODS

In the present study, the effects of the combination of OXA and BC on cell viability, cell cycle arrest, and cancer stemness were investigated using HCT116, HT29, OXA-resistant cells, and human CRC organoids.

RESULTS

The combination of OXA and BC enhanced apoptosis, G2/M phase cell cycle arrest, and inhibited cancer cell survival in human CRC resistant cells and CRC organoids without toxicity in normal organoids. Cancer stem cell marker expression and self-replicating capacity were suppressed by combined treatment with OXA and BC. Moreover, this combined treatment upregulated apoptosis and the stem cell-related JAK/STAT signaling pathway.

CONCLUSIONS

Our results suggest a novel potential role of BC in reducing resistance to OXA, thereby enhances the anticancer effects of OXA. This enhancement is achieved through the regulation of cell cycle, apoptosis, and stemness in CRC.

Caesalpinia pulcherrima lowered serum carcinoembryonic antigen and antigen 125 in 7,12-Dimethylbenz[a]anthracene-induced Mammary Carcinogenesis in Female Albino Rats

Aim

This study is aimed at evaluating the anticancer effect of the aqueous extract of Caesalpinia pulcherrima (L.) Sw in 7,12-Dimethlbenz[a]anthracene (DMBA) - induced mammary cancer.

Methods

Tumors were induced via a single intraperitoneal injection of DMBA (dissolved in olive oil) at a dose of 80 mg/kg body weight to the test rats and allowed to develop for about four months. They were treated with cyclophosphamide and an aqueous extract of Caesalpinia pulcherrima at doses of 10 and 250 mg/kg body weight, respectively, for 28 days. Serum levels of cancer antigen 125 (CA125), carcinoembryonic antigen (CEA) activity, cyclooxygenase-2 (COX-2), and cytochrome p450 oxidase (cytp450) activity, as well as other diagnostic enzymes, were estimated.

Results

The result revealed that DMBA is associated with a significant (p < 0.05) increase in the serum levels of CA125, CEA, COX-2, cytp450, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) of the rats, thus suggesting tumor-promoting and hepatotoxic effects of DMBA. There was also a significant (p < 0.05) reduction of serum levels of these cancer and liver biomarker enzymes in the groups treated with cyclophosphamide and Caesalpinia pulcherrima compared to the untreated group, thus suggesting anticancer activity of Caesalpinia pulcherrima. The anticancer effect of Caesalpinia pulcherrima was further confirmed by the disappearance of infiltrative fibrous cells and the absence of inflammatory cells from the photomicrographs of the rats treated with Caesalpinia pulcherrima.

Conclusion

Our findings show that Caesalpinia pulcherrima possesses anticancer activity, and could protect against mammary cancer.

Emerging Paradigms in Inflammatory Disease Management: Exploring Bioactive Compounds and the Gut Microbiota

The human gut microbiota is a complex ecosystem of mutualistic microorganisms that play a critical role in maintaining human health through their individual interactions and with the host. The normal gastrointestinal microbiota plays a specific physiological function in host immunomodulation, nutrient metabolism, vitamin synthesis, xenobiotic and drug metabolism, maintenance of structural and functional integrity of the gut mucosal barrier, and protection against various pathogens. Inflammation is the innate immune response of living tissues to injury and damage caused by infections, physical and chemical trauma, immunological factors, and genetic derangements. Most diseases are associated with an underlying inflammatory process, with inflammation mediated through the contribution of active immune cells. Current strategies to control inflammatory pathways include pharmaceutical drugs, lifestyle, and dietary changes. However, this remains insufficient. Bioactive compounds (BCs) are nutritional constituents found in small quantities in food and plant extracts that provide numerous health benefits beyond their nutritional value. BCs are known for their antioxidant, antimicrobial, anticarcinogenic, anti-metabolic syndrome, and anti-inflammatory properties. Bioactive compounds have been shown to reduce the destructive effect of inflammation on tissues by inhibiting or modulating the effects of inflammatory mediators, offering hope for patients suffering from chronic inflammatory disorders like atherosclerosis, arthritis, inflammatory bowel diseases, and neurodegenerative diseases. The aim of the present review is to summarise the role of natural bioactive compounds in modulating inflammation and protecting human health, for their safety to preserve gut microbiota and improve their physiology and behaviour.

The effects of FTO gene rs9939609 polymorphism on the association between colorectal cancer and dietary intake

Background

FTO gene is associated with obesity, dietary intake, and the risk of colorectal cancer (CRC). In this study, patients with colorectal cancer were assessed for the interactions between FTO gene polymorphisms and dietary intake.

Methods

This case-control study was carried out on 450 participants aged 35-70 years including 150 patients with colorectal cancer and 300 healthy controls. Blood samples were collected in order to extract DNA and genotyping of FTO gene for rs9939609 polymorphism. A validated 168-item food frequency questionnaire (FFQ) and the Nutritionist-IV software were used to assess dietary intake.

Results

In the participants with the TT genotype of FTO rs9939609 polymorphism, CRC risk was significantly associated with higher intake of dietary fat (OR:1.87 CI95%:1.76-1.99, p = 0.04), vitamin B3 (OR:1.20 CI95%:1.08-1.65, p = 0.04), and vitamin C (OR:1.06 CI95%:1.03-1.15, p = 0.04) and lower intake of β-carotene (OR:0.98 CI95%:0.97-0.99, p = 0.03), vitamin E (OR:0.77 CI95%:0.62-0.95, p = 0.02), vitamin B1 (OR:0.15 CI95%:0.04-0.50, p < 0.01), and biotin (OR:0.72 CI95%:0.0.57-0.92, p = 0.01). No significant association was found between CRC and dietary intake in carriers of AA/AT genotypes after adjustments for the confounders.

Conclusion

CRC risk may be decreased by β-carotene, vitamins E, B1, and biotin only in those without the risk allele of the FTO gene. The association of CRC and diet may be influenced by FTO genotype. Further studies are warranted.

Inhibition of Colon Cancer Cells Via Apoptosis Pathway by Ethanolic Extract of Andaliman (Zanthoxylum Acanthopodium Dc.) Fruits

Andaliman (Zanthoxylum acanthopodium DC.) is an exotic spice from North Sumatra (Indonesia) commonly added to enrich the flavor of Bataknese ethnic food because of its unique aroma and trigeminal sensation. Traditionally, it is also known to have health benefits in the gastrointestinal tract; however no studies have reported it. Therefore, this study aimed to investigate the potency of Andaliman fruit to inhibit the proliferation of HCT-116 and WiDr colon cancer cells and its underlying mechanism of inhibition. Andaliman fruits were extracted using ethanol. The anti-proliferative effect was evaluated using the MTT test, and the underlying mechanism of inhibition was examined using the Real-Time Polymerase Chain Reaction (RT-PCR) and Hoechst staining. Bax and Bcl-2 proteins were used as the markers for the pro-apoptotic and anti-apoptotic gene expression analysis, respectively. Andaliman ethanolic extract showed potential bioactivity to inhibit the growth of WiDr and HCT-116 cells in vitro with IC50 of 95.61 μg.mL-1 and 94.64 μg.mL-1, respectively. The cytotoxicity effect of andaliman was rationalized by the gene expression of Bax and Bcl-2 in a non-dose-dependent manner. In addition, Andaliman extract could increase the apoptotic gene marker expression in both cells at half of their IC50, i.e. 47.81 μg.mL-1 and 47.32 μg.mL-1 for WiDr and HCT-116 cells, respectively. This study demonstrated that Andaliman fruit could be potentially developed as a functional food ingredient to prevent colon cancer by inducing the apoptosis mechanism.

Association of Retinol and Carotenoids Content in Diet and Serum With Risk for Colorectal Cancer: A Meta-Analysis

Background

Colorectal cancer (CRC) risk is linked to serum and dietary retinol and carotenoids, according to clinical and epidemiological research. However, the findings are not consistent. As a result, we did this meta-analysis to determine the link between them.

Methods

From 2000 through 2022, the PubMed, Web of Science, and Embase databases, as well as pertinent article references, were searched and filtered based on inclusion and exclusion criteria and literature quality ratings. High and low intake were used as controls, and OR (odds ratio) or RR (relative risk) and 95% confidence interval were extracted. The extracted data were plotted and analyzed using Stata12.0 software.

Results

A total of 22 relevant studies were included, including 18 studies related to diet and 4 studies related to serum. For high and low intake or concentration controls, the pooled OR was as follows: β-carotene (OR = 0.89, 95% CI: 0.78–1.03), α-carotene (OR = 0.87, 95% CI: 0.72–1.03), lycopene (OR = 0.93, 95% CI: 0.81–1.07), lutein/zeaxanthin (OR = 0.96, 95% CI: 0.87–1.07), β-cryptoxanthin (OR = 0.70, 95% CI: 0.48–1.01), total carotenoids (OR = 0.97, 95% CI: 0.81–1.15), retinol (OR = 0.99, 95% CI: 0.89–1.10), serum carotenoids (OR = 0.73, 95% CI: 0.58–0.93), serum retinol (OR = 0.62, 95% CI: 0.26–1.49). Subgroup analysis was performed according to tumor type, study type and sex.

Conclusion

Total carotenoid intake and Lutein/Zeaxanthin intake were not associated with CRC risk. High β-carotene, α-carotene, lycopene, and β-cryptoxanthin all tended to reduce CRC risk. Serum carotenoid concentrations were significantly inversely associated with CRC risk.

β-Carotene Attenuates Apoptosis and Autophagy via PI3K/AKT/mTOR Signaling Pathway in Necrotizing Enterocolitis Model Cells IEC-6

Background

Necrotizing enterocolitis (NEC) is a devastating disease affecting the gastrointestinal tract in the newborn period. In recent years, the role of apoptosis and autophagy in intestinal mucosal barrier dysfunction has come into prominence in research regarding the pathogenesis of NEC. β-Carotene is a well-known vitamin A precursor, and its content in breast milk is relatively high, especially in the colostrum. In the present study, we investigated the protective effect of β-carotene on necrotizing enterocolitis model cells IEC-6 induced by lipopolysaccharide (LPS).

Methods

CCK-8 assay was performed to evaluate cell viability. The Annexin V-FITC/PI method was used to detect apoptosis. Western blotting was utilized to measure the expression levels of proteins. Immunofluorescence analysis was used to assess the autophagy of IEC-6 cells.

Results

Our findings indicated that β-carotene inhibited the apoptosis of IEC-6 cells by downregulating cleaved caspase-3 levels and Bax levels and upregulating Bcl-2 levels, reducing cell autophagy via downregulating LC3II/I ratio and upregulating p62 levels. In addition, the expression of p-PI3K, p-AKT, and p-mTOR was upregulated after β-carotene treatment. Interestingly, these changes induced by β-carotene were partially reversed by rapamycin and voxtalisib.

Conclusion

In conclusion, our findings indicated that β-carotene can attenuate apoptosis and autophagy of IEC-6 cells induced by LPS via activating the PI3K/AKT/mTOR signaling pathway. Therefore, β-carotene may be a promising drug used in the clinical treatment of NEC.

Gloeothece sp.-Exploiting a New Source of Antioxidant, Anti-Inflammatory, and Antitumor Agents

Bioactive lipidic compounds of microalgae, such as polyunsaturated fatty acids (PUFA) and carotenoids, can avoid or treat oxidation-associated conditions and diseases like inflammation or cancer. This study aimed to assess the bioactive potential of lipidic extracts obtained from Gloeothece sp.–using Generally Recognized as Safe (GRAS) solvents like ethanol, acetone, hexane:isopropanol (3:2) (HI) and ethyl lactate. The bioactive potential of extracts was assessed in terms of antioxidant (ABTS^•+, DPPH^•, ^•NO and O₂^•assays), anti-inflammatory (HRBC membrane stabilization and Cox-2 screening assay), and antitumor capacity (death by TUNEL, and anti-proliferative by BrdU incorporation assay in AGS cancer cells); while its composition was characterized in terms of carotenoids and fatty acids, by HPLC-DAD and GC-FID methods, respectively. Results revealed a chemopreventive potential of the HI extract owing to its ability to: (I) scavenge ^-NO^• radical (IC₅₀, 1258 ± 0.353 µg·mL⁻¹); (II) inhibit 50% of COX-2 expression at 130.2 ± 7.4 µg·mL⁻¹; (III) protect 61.6 ± 9.2% of lysosomes from heat damage, and (IV) induce AGS cell death by 4.2-fold and avoid its proliferation up to 40% in a concentration of 23.2 ± 1.9 µg·mL⁻¹. Hence, Gloeothece sp. extracts, namely HI, were revealed to have the potential to be used for nutraceutical purposes.

Enhancement of Biological and Pharmacological Properties of an Encapsulated Polyphenol: Curcumin

There is a dearth of natural remedies available for the treatment of an increasing number of diseases facing mankind. Natural products may provide an opportunity to produce formulations and therapeutic solutions to address this shortage. Curcumin (CUR), diferuloylmethane; I,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione is the major pigment in turmeric powder which has been reported to exhibit a number of health benefits including, antibacterial, antiviral, anti-cancer, anti-inflammatory and anti-oxidant properties. In this review, the authors attempt to highlight the biological and pharmacological properties of CUR in addition to emphasizing aspects relating to the biosynthesis, encapsulation and therapeutic effects of the compound. The information contained in this review was generated by considering published information in which evidence of enhanced biological and pharmacological properties of nano-encapsulated CUR was reported. CUR has contributed to a significant improvement in melanoma, breast, lung, gastro-intestinal, and genito-urinary cancer therapy. We highlight the impact of nano-encapsulated CUR for efficient inhibition of cell proliferation, even at low concentrations compared to the free CUR when considering anti-proliferation. Furthermore nano-encapsulated CUR exhibited bioactive properties, exerted cytotoxic and anti-oxidant effects by acting on endogenous and cholinergic anti-oxidant systems. CUR was reported to block Hepatitis C virus (HCV) entry into hepatic cells, inhibit MRSA proliferation, enhance wound healing and reduce bacterial load. Nano-encapsulated CUR has also shown bioactive properties when acting on antioxidant systems (endogenous and cholinergic). Future research is necessary and must focus on investigation of encapsulated CUR nano-particles in different models of human pathology.

A Comprehensive Overview of Colon Cancer- A Grim Reaper of the 21st Century

A few decades ago, the incidence of colorectal cancer (CRC) was low and is now the fourth in the list of deadly cancers producing nearly a million deaths annually. A population that is aging along with risk factors such as smoking, obesity, sedentary lifestyle with little or no physical activity, and non-healthy food habits of developed countries can increase the risk of colorectal cancer. The balance in gut microbiota and the metabolites produced during bacterial fermentation within the host plays a significant role in regulating intestinal diseases as well as colorectal cancer development. Recent progress in the understanding of illness resulted in multiple treatment options such as surgery, radiation, and chemotherapy, including targeted therapy and multitherapies. The treatment plan for CRC depends on the location, stage and grade of cancer as well as genomic biomarker tests. Despite all the advancements made in the genetic and molecular aspects of the disease, the knowledge seems inadequate as the drug action as well as the wide variation in drug response did not appear strongly correlated with the individual molecular and genetic characteristics, which suggests the requirement of comprehensive molecular understanding of this complex heterogeneous disease. Furthermore, multitherapies or a broad spectrum approach, which is an amalgamation of the various promising as well as effective therapeutic strategies that can tackle heterogeneity and act on several targets of the disease, need to be validated in clinical studies. The latest treatment options have significantly increased the survival of up to three years in the case of advanced disease. The fact that colorectal cancer is developed from a polypoid precursor, as well as the symptoms of the disease that occur at an advanced stage, underlines how screening programs can help early detection and decrease mortality as well as morbidity from CRC.

Soy-tomato enriched diet reduces inflammation and disease severity in a pre-clinical model of chronic pancreatitis

Chronic pancreatitis (CP) is a fibro-inflammatory syndrome in individuals who develop persistent pathological responses to parenchymal injury or stress. Novel therapeutic or dietary interventions that could lessen inflammation in this disease could significantly improve quality of life in patients with CP. Complex dietary foods like soy and tomatoes are composed of active metabolites with anti-inflammatory effects. Data from our group reports that bioactive agents in soy and tomatoes can reduce pro-inflammatory cytokines and suppressive immune populations. Additionally, our team has developed a novel soy-tomato juice currently being studied in healthy individuals with no toxicities, and good compliance and bioavailability. Thus, we hypothesize that administration of a soy-tomato enriched diet can reduce inflammation and severity of CP. C57BL/6 mice were injected intraperitoneally with 50 μg/kg caeurlein (7 hourly injections, twice weekly) for 6 weeks to induce CP. After 4 weeks of caerulein injections, mice were administered a control or a soy-tomato enriched diet for 2 weeks. Disease severity was measured via immunohistochemical analysis of pancreata measuring loss of acini, fibrosis, inflammation, and necrosis. Serum lipase and amylase levels were analyzed at the end of the study. Inflammatory factors in the serum and pancreas, and immune populations in the spleen of mice were analyzed by cytokine multiplex detection, qRT-PCR, and flow cytometry respectively. Infra-red (IR) sensing of mice was used to monitor spontaneous activity and distress of mice. Mice fed a soy-tomato enriched diet had a significantly reduced level of inflammation and severity of CP (p = 0.032) compared to mice administered a control diet with restored serum lipase and amylase levels (p < 0.05). Mice with CP fed a soy-tomato diet had a reduction in inflammatory factors (TNF-α, IL-1β, IL-5) and suppressive immune populations (myeloid-derived suppressor cells; MDSC) compared to control diet fed mice (p < 0.05). Infra-red sensing to monitor spontaneous activity of mice showed that soy-tomato enriched diet improved total activity and overall health of mice with CP (p = 0.055) and CP mice on a control diet were determined to spend more time at rest (p = 0.053). These pre-clinical results indicate that a soy-tomato enriched diet may be a novel treatment approach to reduce inflammation and pain in patients with CP.

Inhibitory Effect of β-Carotene on Helicobacter pylori-Induced TRAF Expression and Hyper-Proliferation in Gastric Epithelial Cells

Helicobacter pylori infection causes the hyper-proliferation of gastric epithelial cells that leads to the development of gastric cancer. Overexpression of tumor necrosis factor receptor associated factor (TRAF) is shown in gastric cancer cells. The dietary antioxidant β-carotene has been shown to counter hyper-proliferation in H. pylori-infected gastric epithelial cells. The present study was carried out to examine the β-carotene mechanism of action. We first showed that H. pylori infection decreases cellular IκBα levels while increasing cell viability, NADPH oxidase activity, reactive oxygen species production, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, and TRAF1 and TRAF2 gene expression, as well as protein–protein interaction in gastric epithelial AGS cells. We then demonstrated that pretreatment of cells with β-carotene significantly attenuates these effects. Our findings support the proposal that β-carotene has anti-cancer activity by reducing NADPH oxidase-mediated production of ROS, NF-κB activation and NF-κB-regulated TRAF1 and TRAF2 gene expression, and hyper-proliferation in AGS cells. We suggest that the consumption of β-carotene-enriched foods could decrease the incidence of H. pylori-associated gastric disorders.

β-carotene Inhibits Expression of c-Myc and Cyclin E in Helicobacter pylori-infected Gastric Epithelial Cells

Background

Helicobacter pylori infection is a major risk factor in the development of gastric cancer. H. pylori infection of gastric epithelial cells increases the levels of reactive oxygen species (ROS), activates oncogenes, and leads to β-catenin-mediated hyper-proliferation. β-Carotene reduces ROS levels, inhibits oxidant-mediated activation of inflammatory signaling and exhibits anticancer properties. The present study was carried out to determine if β-carotene inhibits H. pylori-induced cell proliferation and the expression of oncogenes c-myc and cyclin E by reducing the levels of β-catenin and phosphorylated glycogen synthase kinase 3β (p-GSK3β).

Methods

Gastric epithelial AGS cells were pre-treated with β-carotene (5 and 10 μM) for 2 hours prior to H. pylori infection and cultured for 6 hours (for determination of the levels of p-GSK3β, GSK3β, and β-catenin) and 24 hours (for determination of cell viability and protein levels of c-myc and cyclin E). Cell viability was determined by the MTT assay and protein levels were determined via western blot-based analysis.

Results

β-Carotene inhibited H. pylori-induced increases in the percentage of viable cells, phosphorylated GSK3β (p-GSK3β), and the levels of β-catenin, c-myc and cyclin E.

Conclusions

β-Carotene inhibits H. pylori-induced hyper-proliferation of gastric epithelial cells by suppressing β-catenin signaling and oncogene expression.

Microalgae in modern cancer therapy: Current knowledge

Cancer is an everyday medical concern which requires an appropriate treatment strategy. The malfunction of cell cycle is a well-established cause for cancer induction. Chemotherapy and radiation are the standard available therapeutic approach for cancer treatment; however severe side effects were reported in association to such treatments, for instance, the efficacy of patients' immune system is adversely affected in apart by radiation. These side effects may be minimized by providing novel remedial preparations. Complementary and alternative medicinal compounds, which were obtained from fresh or marine flora particularly micro and macro algae, were reported to its anti-cancerous activities. Several types of bioactive molecules are also present in microalgae, such as carotenoids, various forms of polysaccharides, vitamins, sterol, fibres, minerals…ect; the great unused biomass of microalgae and their excellent diversity of chemical constituents may introduce a major step in developing of anti-malignant drugs. Previously, such characteristic of microalgal bio-diversity was commercially exploited to make food supplements and gelling substances. However, recently, several investigations were designed to study the potential anti-carcinogenic effect of microalgal extracts, where they mostly concluded their ability to induce apoptotic cancer cell death via caspase dependent or independent pathways. In this review paper, we reported the various species of microalgae that possessed anti-tumor activity, the tumor cell lines altered through using microalgal extracts along with the levels of such extracts that reported to its inhibitor effect against cell cycle and proliferation.

Protective and Restorative Effects of Nutrients and Phytochemicals

Intoroduction:

Dietary intake fundamentally provides reintegration of energy and essential nutrients to human organisms. However, its qualitative and quantitative composition strongly affects individual’s health, possibly being either a preventive or a risk factor. It was shown that nutritional status resulting from long-term exposition to specific diet formulations can outstandingly reduce incidences of most common and most important diseases of the developed world, such as cardiovascular and neoplastic diseases. Diet formulations result from different food combinations which bring specific nutrient molecules. Numerous molecules, mostly but not exclusively from vegetal foods, have been characterized among nutritional components as being particularly responsible for diet capabilities to exert risk reduction. These “bioactive nutrients” are able to produce effects which go beyond basic reintegration tasks, i.e. energetic and/or structural, but are specifically pharmacologically active within pathophysiological pathways related to many diseases, being able to selectively affect processes such as cell proliferation, apoptosis, inflammation, differentiation, angiogenesis, DNA repair and carcinogens activation.

Conclusion:

The present review was aimed to know the molecular mechanisms and pathways of activity of bioactive molecules; which will firstly allow search for optimal food composition and intake, and then use them as possible therapeutical targets and/or diagnostics. Also, the present review discussed the therapeutic effect of both nutrients and phytochemicals.

Mechanisms of Phytonutrient Modulation of Cyclooxygenase-2 (COX-2) and Inflammation Related to Cancer

The link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways. Cyclooxygenase-2 (COX-2), a key enzyme in fatty acid metabolism, is upregulated during both inflammation and cancer. COX-2 is induced by pro-inflammatory cytokines at the site of inflammation and enhanced COX-2-induced synthesis of prostaglandins stimulates cancer cell proliferation, promotes angiogenesis, inhibits apoptosis, and increases metastatic potential. As a result, COX-2 inhibitors are a subject of intense research interest toward potential clinical applications. Epidemiological studies highlight the potential benefits of diets rich in phytonutrients for cancer prevention. Plants contain numerous phytonutrient secondary metabolites shown to modulate COX-2. Studies have shown that these metabolites, some of which are used in traditional medicine, can reduce inflammation and carcinogenesis. This review describes the molecular mechanisms by which phytonutrients modulate inflammation, including studies of carotenoids, phenolic compounds, and fatty acids targeting various inflammation-related molecules and pathways associated with cancer. Examples of pathways include those of COX-2, mitogen-activated protein kinase kinase kinase, mitogen-activated protein kinase, pro-inflammatory cytokines, and transcription factors like nuclear factor kappa B. Such phytonutrient modulation of COX-2 and inflammation continue to be explored for applications in the prevention and treatment of cancer.

Chemopreventive effects of some popular phytochemicals on human colon cancer: a review

The present review summarizes (1) the epidemiology and etiology of colon cancer, (2) generalized cancer chemoprotective mechanisms, and (3) the chemopreventive properties of some popular phytochemicals as well as some phytochemicals developed by our research group recently.

Plant Sterol Esters in Extruded Food Model Inhibits Colon Carcinogenesis by Suppressing Inflammation and Stimulating Apoptosis

Plant sterols in their free forms are known to inhibit colon cancer. Whether these activities persist when compounds are incorporated into processed food is not reported yet. This study aimed to test the ability of plant sterol esters (PSE) incorporated into a nonpuffed extruded food (NPE) model to inhibit colon carcinogenesis. PSE was added into NPE at four concentrations (0.0%, 0.7%, 1.4%, and 2.1%). PSE-NPE activity was tested in azoxymethane/dextran sodium sulfate-induced Balb/c mice. The groups given PSE-NPE did not show any colon tumor formation. Immunohistochemistry results revealed that the group fed with 1.4% PSE had the lowest histoscore for cyclooxygenase-2 expression and the highest histoscore for cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9expressions. The results of this study indicated that even after incorporation into a food system, which is processed using high pressure and temperature, PSE retained its chemopreventive activity. The proposed mechanisms are by suppressing inflammation and inducing apoptosis.

Terpenoids as anti-colon cancer agents - A comprehensive review on its mechanistic perspectives

Multistep model of colon carcinogenesis has provided the framework to advance our understanding of the molecular basis of colon cancer. This multistage process of carcinogenesis takes a long period to transform from a normal epithelial cell to invasive carcinoma. Thus, it provides enough time to intervene the process of carcinogenesis especially through dietary modification. In spite of the in-depth understanding of the colon cancer etiology and pathophysiology and its association with diet, colon cancer remains a major cause of cancer mortality worldwide. Phytochemicals and their derivatives are gaining attention in cancer prevention and treatment strategies because of cancer chemotherapy associated adverse effects. Being the largest group of phytochemicals traditionally used for medicinal purpose in India and China, terpenoids are recently being explored as anticancer agents. Anticancer properties of terpenoids are associated with various mechanisms like counteraction of oxidative stress, potentiating endogenous antioxidants, improving detoxification potential, disrupting cell survival pathways and inducing apoptosis. This review gives a comprehensive idea of naturally occurring terpenoids as useful agents for the prevention of colon cancer with reference to their classes, sources and molecular targets. Based on the explored molecular targets further research in colon cancer chemoprevention is warranted.

Bioactive Compounds Isolated from Microalgae in Chronic Inflammation and Cancer

The risk of onset of cancer is influenced by poorly controlled chronic inflammatory processes. Inflammatory diseases related to cancer development include inflammatory bowel disease, which can lead to colon cancer, or actinic keratosis, associated with chronic exposure to ultraviolet light, which can progress to squamous cell carcinoma. Chronic inflammatory states expose these patients to a number of signals with tumorigenic effects, including nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) activation, pro-inflammatory cytokines and prostaglandins release and ROS production. In addition, the participation of inflammasomes, autophagy and sirtuins has been demonstrated in pathological processes such as inflammation and cancer. Chemoprevention consists in the use of drugs, vitamins, or nutritional supplements to reduce the risk of developing or having a recurrence of cancer. Numerous in vitro and animal studies have established the potential colon and skin cancer chemopreventive properties of substances from marine environment, including microalgae species and their products (carotenoids, fatty acids, glycolipids, polysaccharides and proteins). This review summarizes the main mechanisms of actions of these compounds in the chemoprevention of these cancers. These actions include suppression of cell proliferation, induction of apoptosis, stimulation of antimetastatic and antiangiogenic responses and increased antioxidant and anti-inflammatory activity.

Selective anti-cancer effects of palm phytonutrients on human breast cancer cells

Palm TRF exhibited higher potential to induce death by apoptosis and cleavage of the PARP enzyme as well as suppress expression of NF-κB induced by exposure to TNF-α in human breast cancer cells compared to carotenoids, squalene and co-enzyme Q10.

Antiinflammatory Activity of Gynura bicolor ( Hóng Fèng Cài) Ether Extract Through Inhibits Nuclear Factor Kappa B Activation

This study investigated effects of the Gynura bicolor (Roxb. and Willd.) DC. ether extract (GBEE) on nitric oxide (NO) and prostaglandin (PG)E2 production on the lipopolysaccharide (LPS)-induced inflammatory response in RAW 264.7 cells. A composition analysis of GBEE showed that the major compounds were b-carotene, chlorophyll, and quercetin, respectively. Furthermore, NO and PGE2 levels of 120 μg/ml GBEE-treated cells were 70% and 9.8%, respectively, than those of cells treated with LPS alone. Immunoblots assays showed that the GBEE dose-dependently suppressed LPS-induced inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 protein levels. The GBEE significantly decreased cytosolic phosphorylated (p)-IκBa and nuclear p65 protein expressions. Electrophoresis mobility shift assays indicated that the GBEE effectively inhibited nuclear factor kappa B (NF-κB) activation induced by LPS. These results support a role of the GBEE in suppressing activation of NF-κB to inhibit NO and PGE2 production in the LPS-induced inflammatory response by RAW 264.7 cells.

Microalgal compounds modulate carcinogenesis in the gastrointestinal tract

Gastrointestinal cancers rank second in overall cancer-related deaths. Carotenoids, sulfated polysaccharides, and polyunsaturated fatty acids (PUFAs) from microalgae exhibit cancer chemopreventive features at different stages of carcinogenesis. For instance, sulfated polysaccharides bear a prophylactic potential via blocking adhesion of pathogens to the gastric surface, whereas carotenoids are effective against Helicobacter pylori infection. This effect is notable because H. pylori has been targeted as the primary cause of gastric cancer. Recent results on antitumor and antibacterial compounds synthesized by microalgae are reviewed here, with an emphasis on their impact upon H. pylori infection and derived pathologies accompanying the progression of gastric carcinogenesis.

Dietary derived compounds in cancer chemoprevention

Cancer chemoprevention is defined as the application of natural or synthetic agents to suppress or reverse cancer development and progression. In this field especially diet derived compounds have recently attracted researchers' attention as potential therapeutics generally exerting low toxicity compared with regular drugs. This review presents a survey of recent findings concerning the most promising dietary chemopreventive agents such as green tea polyphenols (i.e. catechins), long-chain polyunsaturated fatty acids, carotenoids, glucosinolates/isothiocyanates, vitamins (i.e. vitamin D and folate) and minerals (i.e. calcium and selenium). Molecular targets involved in intrinsic pathways affected by these natural compounds are also shortly discussed.

β-Carotene and lutein inhibit hydrogen peroxide-induced activation of NF-κB and IL-8 expression in gastric epithelial AGS cells

Reactive oxygen species (ROS) including hydrogen peroxide (H(2)O(2)) are involved in the pathogenesis of gastric inflammation. Interleukin-8 (IL-8) is a potent mediator of the inflammatory response by activating and recruiting neutrophils to the site of infection. Oxidant-sensitive transcription factor NF-κB regulates the expression of IL-8 in the immune and inflammatory events. Carotenoids (carotenes and oxygenated carotenoids) show antioxidant and anti-inflammatory activities. Low intake of β-carotene leads to high risk of gastric cancer. Oxygenated carotenoid lutein inhibited NF-κB activation in experimental uveitis. The present study aims to investigate whether β-carotene and lutein inhibit H(2)O(2)-induced activation of NF-κB and expression of IL-8 in gastric epithelial AGS cells. The cells were treated with carotenoids 2 h prior to the treatment of H(2)O(2). mRNA expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and real time RT-PCR analyses. IL-8 level in the medium was determined by enzyme-linked immunosorbent assay. NF-κB activation was assessed by electrophoretic mobility shift assay. ROS levels of the cells were detected by confocal microscopic analysis for fluorescent dichlorofluorescein. As a result, H(2)O(2 )induced the activation of NF-κB and expression of IL-8 in AGS cells time-dependently. β-Carotene and lutein showed inhibitory effects on H(2)O(2)-induced increase in intracellular ROS levels, activation of NF-κB, and IL-8 expression in AGS cells. In conclusion, supplementation of carotenoids such as β-carotene and lutein may be beneficial for the treatment of oxidative stress-mediated gastric inflammation.

The Mediterranean diet: effects on proteins that mediate fatty acid metabolism in the colon

A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.

Dietary astaxanthin inhibits colitis and colitis-associated colon carcinogenesis in mice via modulation of the inflammatory cytokines

Astaxanthin (AX) is one of the marine carotenoid pigments, which possess powerful biological antioxidant, anti-inflammatory and anti-cancer properties. The purpose of this study is to investigate possible inhibitory effect of AX against inflammation-related mouse colon carcinogenesis and dextran sulfate sodium (DSS)-induced colitis in male ICR mice. We conducted two different experiments. In the first experiment, we evaluated the effects of AX at three dose levels, 50, 100 and 200 ppm in diet, on colitis-associated colon carcinogenesis induced by azoxymethane (AOM)/DSS in mice. In the second, the effects of the AX (100 and 200 ppm) in diet on DSS-induced colitis were determined. We found that dietary AX significantly inhibited the occurrence of colonic mucosal ulcers, dysplastic crypts, and colonic adenocarcinoma at week 20. AX-feeding suppressed expression of inflammatory cytokines, including nuclear factor (NF)-κB, tumor necrosis factor (TNF)-α and interleukin (IL)-1β, inhibited proliferation, and induced apoptosis in the colonic adenocarcinomas. Feeding with 200 ppm AX, but not 100 ppm, significantly inhibited the development of DSS-induced colitis. AX feeding (200 ppm in diet) also lowered the protein expression of NF-κB, and the mRNA expression of inflammatory cytokines, including IL-1β, IL-6, and cyclooxygenase (COX)-2. Our results suggest that the dietary AX suppresses the colitis and colitis-related colon carcinogenesis in mice, partly through inhibition of the expression of inflammatory cytokine and proliferation. Our findings suggest that AX is one of the candidates for prevention of colitis and inflammation-associated colon carcinogenesis in humans.

Targeting COX-2 expression by natural compounds: a promising alternative strategy to synthetic COX-2 inhibitors for cancer chemoprevention and therapy

Cyclooxygenase (COX)-2 is a pro-inflammatory immediate early response protein, chronically up-regulated in many pathological conditions. In autoimmune diseases, it is responsible for degenerative effects whereas in cancer, it correlates with poor prognosis. A constitutive expression of COX-2 is triggered since the earliest steps of carcinogenesis. Consequently, strategies aimed at inhibiting COX-2 enzymatic activity have been clinically applied for the treatment of autoimmune disorders; in addition, the same approaches are currently investigated for anti-cancer purposes. However, COX-2 protein inhibitors (i.e., NSAIDs and COXIBs) are not amenable to prolonged administration since they may cause severe side effects, and efforts are underway to identify alternative approaches for chemoprevention/therapy. COX-2 expression is a multi-step process, highly regulated at transcriptional and post-transcriptional levels. Defects in the modulation of one or both of these steps may be found in pathological conditions. Targeting COX-2 expression may therefore represent a promising strategy, by which the same preventive and therapeutic benefits may be gained while avoiding the severe side effects of COX-2 enzymatic inhibition. Naturally occurring compounds derived from plants/organisms represent a huge source of biologically active molecules, that remains largely unexplored. Derived from plants/organisms used in traditional forms of medicine or as dietary supplements, these compounds have been experimentally investigated for their anti-inflammatory and anti-cancer potential. In this review, we will analyze how natural compounds may modulate the multistep regulation of COX-2 gene expression and discuss their potential as a new generation of COX-2 targeting agents alternative to the synthetic COX-2 inhibitors.

Growth-inhibitory effects of the astaxanthin-rich alga Haematococcus pluvialis in human colon cancer cells

The growth-inhibitory effects of the astaxanthin-rich Haematococcus pluvialis were studied in HCT-116 colon cancer cells. H. pluvialis extract (5-25 microg/ml) inhibited cell growth in a dose- and time-dependent manner, by arresting cell cycle progression and by promoting apoptosis. At 25 microg/ml of H. pluvialis extract, an increase of p53, p21(WAF-1/CIP-1) and p27 expression (220%, 160%, 250%, respectively) was observed, concomitantly with a decrease of cyclin D1 expression (58%) and AKT phosphorylation (21%). Moreover, the extract, at the same concentration, strongly up-regulated apoptosis by modifying the ratio of Bax/Bcl-2 and Bcl-XL, and increased the phosphorylation of p38, JNK, and ERK1/2 by 160%, 242%, 280%, respectively. Growth-inhibitory effects by H. pluvialis were also observed in HT-29, LS-174, WiDr, SW-480 cells. This study suggests that H. pluvialis may protect from colon cancer.

NMR metabolomic analysis of fecal water from subjects on a vegetarian diet

A vegetarian diet rich in phytochemicals may prevent colon carcinogenesis by affecting biochemical processes in the colonic mucosa. Compounds passing the digestive system reaching the colon could potentially be detected in fecal water. We previously reported that intact fecal water samples from human volunteers significantly decreased prostaglandin production and COX-2 protein expression in colonic cells. The aim with the present study was to further study the composition of the fecal waters, using NMR spectroscopy and multivariate data analysis, and to trace the COX-2 inhibiting activity. Intact fecal water samples and fractions thereof were analyzed for their ability to inhibit prostaglandin E2 production in the human colon cell line HT-29. The majority of the tested aqueous phases derived from intact fecal water showed ability to inhibit prostaglandin production in cells (13.8+/-1.34% inhibition, p=0.01). NMR analysis indicated the presence of significant quantities of amino acids and fatty acids. Major metabolites included; acetic acid, butanoic acid, propanoic acid, glutamic acid and alanine. Smaller amounts of glycine and fumaric acid, which are known to have anti-inflammatory and anti-tumorigenic properties, were also detected. This study describes for the first time NMR metabolomic analysis of fecal water from subjects on a vegetarian diet.

beta-Carotene induces apoptosis and up-regulates peroxisome proliferator-activated receptor gamma expression and reactive oxygen species production in MCF-7 cancer cells

Although the pharmacological role of beta-carotene in the prevention and treatment of many cancer cells has received increasing attention, the molecular mechanisms underlying such chemopreventive activity are not clear. Since peroxisome proliferator-activated receptor gamma (PPAR-gamma) has been implicated in regulating breast cancer cell differentiation and apoptosis, the effects of beta-carotene on the PPAR-gamma-mediated pathway and its association with reactive oxygen species production in MCF-7 cells were investigated in the present study. The results demonstrated that beta-carotene significantly increased PPAR-gamma mRNA and protein levels in time-dependent manner. In addition, beta-carotene increased the cyclin-dependent kinase inhibitor p21(WAF1/CIP1) expression and decreased the prostanoid synthesis rate-limiting enzyme cyclooxygenase-2 expression. 2-chloro-5-nitro-N-phenylbenzamide (GW9662), an irreversible PPAR-gamma antagonist, partly attenuated the cell death caused by beta-carotene. Further, reactive oxygen species (ROS) production was induced by beta-carotene, resulting in mitochondrial dysfunction and cytochrome C release. Reduced glutathione (GSH) treatment decreases the intracellular ROS and prevents cytochrome C release and cell apoptosis induced by beta-carotene. In total, these observations suggest that the synergistic effect of PPAR-gamma expression and ROS production may account for beta-carotene-mediated anticancer activities.

Anticancer effects of Chinese red yeast rice versus monacolin K alone on colon cancer cells

Chinese red yeast rice (RYR) is a food herb made by fermenting Monascus purpureus Went yeast with white rice. RYR contains a mixture of monacolins, one of which--monacolin K (MK)--is identical to lovastatin (LV). Epidemiological studies show that individuals taking statins have a reduced risk of colon cancer. In the present study, LV decreased cellular proliferation (P<.001) and induced apoptosis (P<.05) in HCT-116 and HT-29 human colon cancer cells. RYR inhibited both tumor cell growths (P<.001) and enhanced apoptosis (P<.05) in HCT-116 cells. Inhibition of proliferation was reversed by mevalonate (MV) in LV-treated cells, since LV is a 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGCR) inhibitor. However, RYR with MV did not reverse the observed inhibition of growth. MK-free RYR did not reverse the observed LV-mediated inhibition of cancer cell growth. These observations suggest that other components in RYR, including other monacolins, pigments or the combined matrix effects of multiple constituents, may affect intracellular signaling pathways differently from purified crystallized LV in colon cancer cells. RYR was purified into two fractions: pigment-rich fraction of Chinese red yeast rice (PF-RYR) and monacolin-rich fraction of Chinese red yeast rice (MF-RYR). The effect of MF-RYR was similar to that of LV, while the effect of PF-RYR was similar to the effect of the whole RYR extract on the proliferation, apoptosis and mRNA level of HMGCR and sterol response element binding protein-2. These results suggest that the matrix effects of RYR beyond MK alone may be active in inhibiting colon cancer growth. RYR with or without MK may be a botanical approach to colon cancer chemoprevention worthy of further investigation.

Inhibition of p38/CREB phosphorylation and COX-2 expression by olive oil polyphenols underlies their anti-proliferative effects

We investigated the anti-proliferative effects of an olive oil polyphenolic extract on human colon adenocarcinoma cells. Analysis indicated that the extract contained hydroxytyrosol, tyrosol and the various secoiridoid derivatives, including oleuropein. This extract exerted a strong inhibitory effect on cancer cell proliferation, which was linked to the induction of a G2/M phase cell cycle block. Following treatment with the extract (50 microg/ml) the number of cells in the G2/M phase increased to 51.82+/-2.69% relative to control cells (15.1+/-2.5%). This G2/M block was mediated by the ability of olive oil polyphenols (50 microg/ml) to exert rapid inhibition of p38 (38.7+/-4.7%) and CREB (28.6+/-5.5%) phosphorylation which led to a downstream reduction in COX-2 expression (56.9+/-9.3%). Our data suggest that olive oil polyphenols may exert chemopreventative effects in the large intestine by interacting with signalling pathways responsible for colorectal cancer development.

A highly polar xanthophyll of 9'-cis-neoxanthin induces apoptosis in HCT116 human colon cancer cells through mitochondrial dysfunction

Highly polar xanthophylls of 9'-cis-neoxanthin (neoxanthin) and fucoxanthin, which have the characteristic structure of an epoxy group and an allenic bond, were previously found to induce apoptosis in human prostate cancer cells. In the present study, we found apoptosis induction by neoxanthin in HCT116 human colon cancer cells and examined the induction mechanism. The cells exposed to 20 microM neoxanthin clearly showed chromatin condensation, DNA fragmentation, and an increase in hypodiploid cells. Neoxanthin treatment increased the activities of caspase-3, -8 and -9, and the protein levels of their active subunits, except in the case of caspase-8. The treatment also caused the loss of mitochondrial transmembrane potential at an early stage and subsequently the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to cytosol. The exposure of neoxanthin directly to mitochondria isolated from the cells enhanced the release of cytochrome c and AIF in a dose-dependent manner. Approximately 50% of the neoxanthin taken up into the HCT116 cells accumulated in the mitochondrial fraction. These results suggest that the accumulation of neoxanthin in mitochondria causes the loss of mitochondrial transmembrane potential and thereafter releases cytochrome c and AIF, leading to the execution of apoptosis.

Dietary supplementation with antioxidants improves functions and decreases oxidative stress of leukocytes from prematurely aging mice

OBJECTIVES

Aging is accompanied by chronic inflammation and oxidative stress, which lead to a marked impairment of immune function and therefore increased mortality. This study assessed the effect of dietary supplementation, for 15 wk, with 5% and 20% (w/w) of biscuits enriched with nutritional doses of vitamins C and E, zinc, selenium, and beta-carotenes on function and oxidative stress parameters of peritoneal leukocytes from middle-aged, prematurely aging mice (PAM) and non-prematurely aging mice (NPAM).

METHODS

After supplementation we measured leukocyte functions (adherence, chemotaxis, phagocytosis, intracellular reactive oxygen species levels, lymphoproliferation, natural killer activity, and interleukin-2 release), antioxidant defenses (superoxide dismutase, glutathione peroxidase, and reduced glutathione), oxidant compounds (extracellular O(2)(-), glutathione disulfide, glutathione disulfide/reduced glutathione ratio, tumor necrosis factor-alpha, nitric oxide, and prostaglandin E(2)), and lipid and DNA oxidative damage, measured by malondialdehyde and 8-oxo,7,8-dihydro-2'-deoxyguanosine levels, respectively.

RESULTS

In general, leukocyte functions were improved and redox homeostasis was restored after intake of antioxidants. In consequence, malondialdehyde and 8-oxo,7,8-dihydro-2'-deoxyguanosine in PAM and NPAM were strikingly decreased after 5% and 20% supplementation (malondialdehyde, P < 0.001 in PAM; P < 0.01 in NPAM after both treatments; 8-oxo,7,8-dihydro-2'-deoxyguanosine, P < 0.01 after 5% supplementation and P < 0.001 after 20% supplementation in PAM and NPAM). Moreover, the effect of the antioxidants was stronger in PAM than in NPAM, and 20% supplementation was more effective than 5%.

CONCLUSION

Our data suggest that improvement of leukocyte function and restoration of redox balance after consumption of adequate levels of antioxidants from adulthood may be useful to attain healthy aging, especially in animals with premature aging.

Oxidative stress in leukocytes from young prematurely aging mice is reversed by supplementation with biscuits rich in antioxidants

Aging is associated with a progressive dysregulation of immune responses as a result of increased oxidative stress. Therefore, we have assessed the oxidative stress status of peritoneal leukocytes from young prematurely aging mice (PAM) as compared with non-prematurely aging mice (NPAM), as well as the effects on this oxidative stress of a dietary supplementation with biscuits rich in antioxidants (vitamin C, vitamin E, beta-carotenes, zinc and selenium). We found that, in the peritoneal leukocytes, the levels of several parameters of oxidation such as extracellular superoxide anion (O(2)(-)), Prostaglandin E(2) (PGE(2)), nitric oxide, oxidized glutathione (GSSG) and lipid peroxidation (malondialdehyde, MDA) were higher in PAM as compared with NPAM, whereas the antioxidant defences such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, as well as reduced glutathione (GSH) levels, were decreased. Consequently, young PAM showed an oxidative stress in their leukocytes, which is characteristic of mice of an older chronological age. Antioxidant diet supplementation was able to restore redox homeostasis, increasing the antioxidant and decreasing the oxidant levels. Accordingly, supplementation with adequate levels of antioxidants, from an early age, could be useful to preserve health, especially in prematurely aging populations.

Lycopene induces apoptosis in immortalized fibroblasts exposed to tobacco smoke condensate through arresting cell cycle and down-regulating cyclin D1, pAKT and pBad

There is a lot of interest in the health benefits of dietary carotenoids and on the relationship of these compounds with smoke. In particular, it is unknown if the enhanced cancer risk observed in smokers following beta-carotene supplementation can be also found using other carotenoids. Here, we studied the effects of the tomato carotenoid lycopene on molecular pathways involved in cell cycle progression, apoptosis and survival in immortalized RAT-1 fibroblasts exposed to cigarette smoke condensate (TAR). Lycopene (0.5-2.0 microM) inhibited cell growth in a dose-and time-dependent manner, by arresting cell cycle progression and by promoting apoptosis in cells exposed to TAR. The arrest of cell cycle was independent of p53 and of 8-OH-dG DNA damage and related to a decreased expression of cyclin D1. Moreover, the carotenoid up-regulated apoptosis and down-regulated the phosphorylation of AKT and Bad in cells exposed to TAR. Such an effect was associated to an inhibition of TAR-induced expression of Cox-2 and hsp90, which is known to maintain AKT activity. This study suggests that lycopene, differently from beta-carotene, can exert protective effects against cigarette smoke condensate.

Tobacco use and associations of beta-carotene and vitamin intakes with colorectal adenoma risk

The effects of vitamins and beta-carotene on the risk of colorectal adenomas have not been fully investigated. Recent data suggest that smoking could modulate the effect of beta-carotene supplements on adenoma recurrence. We investigated the effect of dietary vitamins and beta-carotene on the risk of adenomas, and a potential interaction with smoking status as part of a case-control study of environmental factors associated with the risk of colorectal adenomas and cancers. We compared nutrient intakes in polyp-free controls (n = 427) and adenoma cases (n = 362) globally and using models stratified by smoking status, adjusted for age, sex, BMI, and energy and alcohol intakes. Folate and vitamins C and B-6 were inversely related to adenoma risk (P for trend = 0.005, 0.03, and 0.02, respectively), whereas vitamin D tended to be inversely associated with risk (P for trend = 0.05). There was a significant interaction between beta-carotene and smoking (P interaction = 0.04). In nonsmokers, beta-carotene was inversely associated with adenoma risk, especially that of colon adenomas [odds ratios (ORs) in low vs. high consumers and 95% CI 0.4 (0.2-0.9)], whereas in past or current smokers, beta-carotene was associated with a nonsignificant (P for trend = 0.19) increase in the risk of colon adenomas [corresponding OR = 1.9 (95% CI = 0.9-4.1)]. Our findings support a protective effect of folate and vitamins C and B-6 irrespective of smoking habits, and a protective effect of beta-carotene in nonsmokers only. They suggest an adverse effect of beta-carotene in smokers, who should be cautious about taking high doses of this micronutrient.

Dual Association of beta-carotene with risk of tobacco-related cancers in a cohort of French women

BACKGROUND

Intervention studies have demonstrated that, in smokers, beta-carotene supplements had a deleterious effect on risk of lung cancer and may have a deleterious effect on digestive cancers as well. We investigated a potential interaction between beta-carotene intake and smoking on the risk of tobacco-related cancers in women.

METHODS

A total of 59,910 women from the French Etude Epidémiologique de Femmes de la Mutuelle Générale de l'Education Nationale (E3N) prospective investigation were studied from 1994. After a median follow-up of 7.4 years, 700 women had developed cancers known to be associated with smoking. Diet, supplement use, and smoking status at baseline were assessed by self-report. beta-carotene intake was classified into four groups: first (low intake), second, and third tertiles of dietary intake, and use of supplements (high intake). Unadjusted and multivariable Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals (CIs) for cancer risk. All statistical tests were two-sided.

RESULTS

Among never smokers, multivariable hazard ratios of all smoking-related cancers were 0.72 (95% CI = 0.57 to 0.92), 0.80 (95% CI = 0.64 to 1.01), and 0.44 (95% CI = 0.18 to 1.07) for the second and third tertiles of dietary intake, and high beta-carotene intake, respectively, compared with low intake (Ptrend = .03). Among ever smokers, multivariable hazard ratios were 1.43 (95% CI = 1.05 to 1.96), 1.20 (95% CI = 0.86 to 1.67), and 2.14 (95% CI = 1.16 to 3.97) for the second and third tertiles of dietary intake, and high beta-carotene intake, respectively, compared with low intake (Ptrend = .09). Tests for interaction between beta-carotene intake and smoking were statistically significant (Ptrend =.017). In this population, the absolute rates over 10 years in those with low and high beta-carotene intake were 181.8 and 81.7 cases per 10,000 women in never smokers and 174.0 and 368.3 cases per 10,000 women in ever smokers.

CONCLUSIONS

beta-carotene intake was inversely associated with risk of tobacco-related cancers among nonsmokers with a statistically significant dose-dependent relationship, whereas high beta-carotene intake was directly associated with risk among smokers.