The role of antioxidants and pro-oxidants in colon cancer

Gut Microbiota Fermentation of Digested Almond-Psyllium-Flax Seed-Based Artisan Bread Promotes Mediterranean Diet-Resembling Microbial Community

Different modifications of the standard bread recipe have been proposed to improve its nutritional and health benefits. Here, we utilized the in vitro Human Gut Simulator (HGS) to assess the fermentation of one such artisan bread by human gut microbiota. Dried and milled bread, composed of almond flour, psyllium husks, and flax seeds as its three main ingredients, was first subjected to an in vitro protocol designed to mimic human oro-gastro-intestinal digestion. The bread digest was then supplied to complex human gut microbial communities, replacing the typical Western diet-based medium (WM) of the GHS system. Switching the medium from WM to bread digest resulted in statistically significant alterations in the community structure, encoded functions, produced short-chain fatty acids, and available antioxidants. The abundances of dietary fiber degraders Enterocloster, Mitsuokella, and Prevotella increased; levels of Gemmiger, Faecalibacterium, and Blautia decreased. These community alterations resembled the previously revealed differences in the distal gut microbiota of healthy human subjects consuming typical Mediterranean vs. Western-pattern diets. Therefore, the consumption of bread high in dietary fiber and unsaturated fatty acids might recapitulate the beneficial effects of the Mediterranean diet on the gut microbiota.

Chemopreventive Effect of an In Vitro Digested and Fermented Plant Sterol-Enriched Wholemeal Rye Bread in Colon Cancer Cells

Diet is crucial for the prevention of colorectal cancer. Whole grains are the source of beneficial compounds for this, such as fiber. The enrichment of wholemeal rye bread with plant sterols (PSs) could increase its beneficial effects. This study aimed to assess the potential antiproliferative effect of this enriched food on colon adenocarcinoma cells (Caco-2) compared with a non-enriched one. After a human oral chewing, simulated semi-dynamic gastrointestinal digestion and colonic fermentation in a simgi® system, fermentation liquids (FLs) obtained were used as treatment for cells. Cytotoxicity assay showed that samples diluted 1/5 (v/v) with DMEM are not toxic for non-tumoral cells, whereas they damage tumoral cells. Samples with PS (FLPS) produced a higher chemopreventive effect (vs. blank) in MTT and apoptosis assays, as well as higher gene expression of TP53 and Casp8. Nevertheless, FL0 (without PS) produced a higher chemopreventive effect in a cell cycle and reduced glutathione and calcium assays, besides producing higher gene expression of Casp3 and lower CCND1. The distinct antiproliferative effect of both FLs is attributed to differences in PSs, short chain fatty acids (lower concentration in FLPS vs. FL0) and antioxidant compounds. These results may support wholemeal rye bread consumption as a way of reducing the risk of colorectal cancer development, although further research would be needed.

Association between oxidative stress exposure and colorectal cancer risk in 98,395 participants: results from a prospective study

Background

The intricate role of oxidative stress (OS) in colorectal cancer (CRC) initiation is underscored by an imbalance between pro-oxidants and antioxidants. Utilizing the Oxidative Balance Score (OBS) as a metric, this study aims to investigate the association between OS exposure and CRC risk, while also examining potential sex-specific differences in a large U.S. cohort.

Methods

The study included 98,395 adults from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. To construct the OBS, 14 dietary and lifestyle factors intricately associated with oxidative stress were quantified. A higher OBS value indicated a more favorable oxidative balance pattern or diminished OS exposure. Due to sex-specific differences in OBS, associations were evaluated separately for men and women based on Cox regression analysis. Subgroup analyses were conducted to elucidate potential modifiers.

Results

During 867,963.4 person-years of follow-up, 1,054 CRCs occurred. The mean (SD) age and OBS were 65.52 (5.73) years and 14.09 (3.95) points, respectively. In the fully adjusted Cox model, we observed an inverse association between OBS and CRC incidence in women (HRQ5vsQ1: 0.72; 95% CI: 0.52, 0.99; P for trend = 0.018) but not men. Subgroup analyses revealed the inverse association was more pronounced among women without versus with a family history of CRC (HRQ5 vsQ1: 0.66, 95% CI: 0.47-0.93; P for trend = 0.001; P for interaction = 0.001). The results remained robust after several sensitivity analyses.

Conclusion

Higher OBS was associated with lower CRC risk in women but not men; this inverse association was stronger among women without a family history of CRC. These findings suggest exposure to OS may confer sex-specific CRC risk effects, especially for women without a family history of CRC.

Prediagnostic serum glyceraldehyde-derived advanced glycation end products and mortality among colorectal cancer patients

Glyceraldehyde-derived advanced glycation end products (glycer-AGEs) could contribute to colorectal cancer development and progression due to their pro-oxidative and pro-inflammatory properties. However, the association of glycer-AGEs with mortality after colorectal cancer diagnosis has not been previously investigated. Circulating glycer-AGEs were measured by competitive ELISA. Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for associations of circulating glycer-AGEs concentrations with CRC-specific and all-cause mortality among 1034 colorectal cancer (CRC) cases identified within the European Prospective Investigation into Cancer and Nutrition (EPIC) study between 1993 and 2013. During a mean of 48 months of follow-up, 529 participants died (409 from CRC). Glycer-AGEs were statistically significantly positively associated with CRC-specific (HRQ5 vs Q1  = 1.53, 95% CI: 1.04-2.25, Ptrend  = .002) and all-cause (HRQ5 vs Q1  = 1.62, 95% CI: 1.16-2.26, Ptrend  < .001) mortality among individuals with CRC. There was suggestion of a stronger association between glycer-AGEs and CRC-specific mortality among patients with distal colon cancer (per SD increment: HRproximal colon  = 1.02, 95% CI: 0.74-1.42; HRdistal colon  = 1.51, 95% CI: 1.20-1.91; Peffect modification  = .02). The highest HR was observed among CRC cases in the highest body mass index (BMI) and glycer-AGEs category relative to lowest BMI and glycer-AGEs category for both CRC-specific (HR = 1.78, 95% CI: 1.02-3.01) and all-cause mortality (HR = 2.15, 95% CI: 1.33-3.47), although no statistically significant effect modification was observed. Our study found that prediagnostic circulating glycer-AGEs are positively associated with CRC-specific and all-cause mortality among individuals with CRC. Further investigations in other populations and stratifying by tumor location and BMI are warranted.

Resveratrol Attenuates the Mitochondrial RNA-Mediated Cellular Response to Immunogenic Stress

Human mitochondria contain a circular genome that encodes 13 subunits of the oxidative phosphorylation system. In addition to their role as powerhouses of the cells, mitochondria are also involved in innate immunity as the mitochondrial genome generates long double-stranded RNAs (dsRNAs) that can activate the dsRNA-sensing pattern recognition receptors. Recent evidence shows that these mitochondrial dsRNAs (mt-dsRNAs) are closely associated with the pathogenesis of human diseases that accompany inflammation and aberrant immune activation, such as Huntington's disease, osteoarthritis, and autoimmune Sjögren's syndrome. Yet, small chemicals that can protect cells from a mt-dsRNA-mediated immune response remain largely unexplored. Here, we investigate the potential of resveratrol (RES), a plant-derived polyphenol with antioxidant properties, on suppressing mt-dsRNA-mediated immune activation. We show that RES can revert the downstream response to immunogenic stressors that elevate mitochondrial RNA expressions, such as stimulation by exogenous dsRNAs or inhibition of ATP synthase. Through high-throughput sequencing, we find that RES can regulate mt-dsRNA expression, interferon response, and other cellular responses induced by these stressors. Notably, RES treatment fails to counter the effect of an endoplasmic reticulum stressor that does not affect the expression of mitochondrial RNAs. Overall, our study demonstrates the potential usage of RES to alleviate the mt-dsRNA-mediated immunogenic stress response.

Jaboticaba (Myrciaria cauliflora) Fruit Extract Suppressed Aberrant Crypt Formation in 1,2-Dimetylhydrazine-Induced Rats

Early intervention can significantly improve the colorectal cancer survival rate. Foods rich in phenolic compounds, such as jaboticaba (Myrciaria cauliflora), may prevent tumorigenesis. We investigated the effectivity of jaboticaba whole fruit ethanolic extract (FEX) in suppressing aberrant crypt foci (ACF), the earliest lesion of colorectal cancer (CRC), in 1,2-dimethylhydrazine (DMH)-induced rats and the underlying mechanisms related to the gut microbiota composition and short chain fatty acid (SCFA). This study was approved by the Institutional Animal Care and Use Committee (IACUC) of Providence University (Trial Registration Number 20180419A01, registration date: 22 December 2018). The FEX contains gallic acid and an especially high ellagic acid concentration of 54.41 ± 1.80 and 209.79 ± 2.49 mg/100 g FEX. The highest total ACF number (150.00 ± 43.86) was recorded in the DMH control (D) group. After 56 days of oral FEX treatment, the total ACF number in the low FEX dosage (DL) group was significantly lower compared to the D group (p < 0.05). The large-sized ACF (> 5 foci), which has a higher probability of progressing to later stage, was significantly decreased in the high FEX dosage (DH) group. The 16s rDNA metagenomic sequencing of the cecal material revealed that the CRC biomarker Lachnoclostridium was significantly suppressed in the DH group (p < 0.05), whereas some SCFA-producing taxa and the cecal butyrate concentration were significantly elevated in the DL and DH groups (p < 0.05). This study demonstrated the potential of jaboticaba whole fruit in CRC prevention, especially in the initial stage, by shifting gut microbiota composition and improving cecal butyrate level.

CeO2-Azacrown Conjugate as a Nanoplatform for Combined Radiopharmaceuticals

This study is one of the first attempts to assess CeO₂ nanoparticles as a nanoplatform for radiopharmaceuticals with radionuclides. The process of functionalization using a bifunctional azacrown ligand is described, and the resulting conjugates are characterized by IR and Raman spectroscopy. Their complexes with ²⁰⁷Bi show a high stability in medically relevant media, thus encouraging the further study of these conjugates in vivo as potential combined radiopharmaceuticals.

Copper Nanoparticles Induce Apoptosis and Oxidative Stress in SW480 Human Colon Cancer Cell Line

Cu nanoparticles (CuNPs) have various applications in biomedicine, owing to their unique properties. As the effect of CuNPs on the induction of oxidative stress and apoptosis in the human colorectal cancer cell line SW480 has not yet been studied, we investigated the toxicity and mechanism of action of these NPs in SW480 cells. MTT assay was performed to assess the effect of the particles on the viability of SW480 cells. The levels of oxidative stress were assessed after 24 h of treatment with CuNPs by evaluating the Reactive Oxygen Specious (ROS) production. The antioxidant enzyme activity was assessed using a colorimetric method. To investigate the effect of NPs on cellular apoptosis, Hoechst33258 staining was performed, and the expression of Bax, Bcl-2, and p53 was evaluated by qRT-PCR. The MTT assay results showed that CuNPs inhibited the viability of SW480 cells. Moreover, the increase in ROS production at all three concentrations (31, 68, and 100 μg/ml) was significant. It has been observed that CuNPs lead to increased expression of Bax and p53, and decreased expression of Bcl-2. Hoechst staining was performed to confirm apoptosis. In conclusion, the induction of apoptosis demonstrated the anticancer potential of the CuNPs.

Synthesis and Evaluation of Some New 4H-Pyran Derivatives as Antioxidant, Antibacterial and Anti-HCT-116 Cells of CRC, with Molecular Docking, Antiproliferative, Apoptotic and ADME Investigations

Colorectal cancer oncogenesis is linked to dysbiosis, oxidative stress and overexpression of CDK2. The 4H-pyran scaffold is considered an antitumoral, antibacterial and antioxidant lead as well as a CDK2 inhibitor. Herein, certain 4H-pyran derivatives were evaluated as antibacterial, antioxidant and cytotoxic agents against HCT-116 cells. Derivatives 4g and 4j inhibited all the tested Gram-positive isolates, except for B. cereus (ATCC 14579), with lower IC₅₀ values (µM) than ampicillin. In addition, 4g and 4j demonstrated the strongest DPPH scavenging and reducing potencies, with 4j being more efficient than BHT. In cell viability assays, 4d and 4k suppressed the proliferation of HCT-116 cells, with the lowest IC₅₀ values being 75.1 and 85.88 µM, respectively. The results of molecular docking simulations of 4d and 4k, inhibitory kinase assays against CDK2, along with determination of CDK2 protein concentration and the expression level of CDK2 gene in the lysates of HCT-116 treated cells, suggested that these analogues blocked the proliferation of HCT-116 cells by inhibiting kinase activity and downregulating expression levels of CDK2 protein and gene. Moreover, 4d and 4k were found to induce apoptosis in HCT-116 cells via activation of the caspase-3 gene. Lastly, compounds 4g, 4j, 4d and 4k were predicted to comply with Lipinski’s rule of five, and they are expected to possess excellent physiochemical and pharmacokinetic properties suitable for in vivo bioavailability, as predicted by the SwissADME web tool.

Colorectal Cancer Chemoprevention by S-Allyl Cysteine–Caffeic Acid Hybrids: In Vitro Biological Activity and In Silico Studies

Conventional chemotherapy for colorectal cancer (CRC) gives only a small increase in patient survival, since it is often diagnosed at late stages, when the tumor has disseminated to other organs. Moreover, it is common to observe that malignant cells may acquire resistance to conventional chemotherapies through different mechanisms, including reducing drug activation or accumulation (by enhancing efflux), inducing alterations in molecular targets, and inhibiting the DNA damage response, among other strategies. Considering these facts, the discovery of new molecules with therapeutic potential has become an invaluable tool in chemoprevention. In this context, we previously evaluated two hybrids (SAC-CAFA-MET and SAC-CAFA-PENT) that exhibited selective cytotoxicity against SW480 cells, with better results than the conventional chemotherapeutic agent (5-fluorouracil; 5-FU). Here, we investigated the possible mechanisms of these molecules in greater depth, to identify whether they could be valuable therapeutic scaffolds in the search for new molecules with chemopreventive potential for the treatment of CRC. Both compounds reduced ROS formation, which could be related to antioxidant effects. Further evaluations showed that SAC-CAFA-MET induces cell death independent of caspases and the tumor-suppressor protein p53, but probably mediated by the negative regulation of the pro-apoptotic Bcl-2. In addition, the lack of activation of caspase-8 and the positive regulation of caspase-3 induced by SAC-CAFA-PENT suggest that this compound acts through an apoptotic mechanism, probably initiated by intrinsic pathways. Furthermore, the downregulation of IL-6 by SAC-CAFA-PENT suggests that it also induces a significant anti-inflammatory process. In addition, docking studies would suggest caspase-3 modulation as the primary mechanism by which SAC-CAFA-PENT elicits apoptosis in SW480human colorectal adenocarcinoma cells. Meanwhile, density functional theory (DFT) calculations suggest that both hybrids would produce effects in the modulation of ROS in SW480 cells via the hydrogen atom transfer (HAT) pathway. The present work notes that SAC-CAFA-MET and SAC-CAFA-PENT could be potential candidates for further investigations in the search for potential chemopreventive agents.

Dietary Intake of Advanced Glycation End Products (AGEs) and Mortality among Individuals with Colorectal Cancer

Advanced glycation end-products (AGEs) may promote oxidative stress and inflammation and have been linked to multiple chronic diseases, including cancer. However, the association of AGEs with mortality after colorectal cancer (CRC) diagnosis has not been previously investigated. Multivariable Cox proportional hazards models were used to calculate hazard ratios and corresponding 95% confidence intervals for associations between dietary intake of AGEs with CRC-specific and all-cause mortality among 5801 participant cases diagnosed with CRC in the European Prospective Investigation into Cancer and Nutrition study between 1993 and 2013. Dietary intakes of AGEs were estimated using country-specific dietary questionnaires, linked to an AGE database, that accounted for food preparation and processing. During a median of 58 months of follow-up, 2421 cases died (1841 from CRC). Individually or combined, dietary intakes of AGEs were not associated with all-cause and CRC-specific mortality among cases. However, there was a suggestion for a positive association between AGEs and all-cause or CRC-specific mortality among CRC cases without type II diabetes (all-cause, Pinteraction = 0.05) and CRC cases with the longest follow-up between recruitment and cancer diagnosis (CRC-specific, Pinteraction = 0.003; all-cause, Pinteraction = 0.01). Our study suggests that pre-diagnostic dietary intakes of AGEs were not associated with CRC-specific or all-cause mortality among CRC patients. Further investigations using biomarkers of AGEs and stratifying by sex, diabetes status, and timing of exposure to AGEs are warranted.

Microenvironmental Reactive Oxygen Species in Colorectal Cancer: Involved Processes and Therapeutic Opportunities

Colorectal cancer (CRC) is the fourth most common cause of cancer deaths worldwide. Although screening programs have reduced mortality rates, there is a need for research focused on finding the main factors that lead primary CRC to progress and metastasize. During tumor progression, malignant cells modify their habitat, corrupting or transforming cells of different origins and creating the tumor microenvironment (TME). Cells forming the TME like macrophages, neutrophils, and fibroblasts generate reactive oxygen species (ROS) that modify the cancer niche. The effects of ROS in cancer are very diverse: they promote cellular proliferation, epithelial-to-mesenchymal transition (EMT), evasion of cell death programs, migration, and angiogenesis. Due to the multifaceted role of ROS in cancer cell survival and function, ROS-modulating agents such as antioxidants or pro-oxidants could have therapeutic potential in cancer prevention and/or as a complement to systemic treatments. In this review, we will examine the main ROS producer cells and their effects on cancer progression and metastasis. Furthermore, we will enumerate the latest clinical trials where pro-oxidants and antioxidants have therapeutic uses in CRC.

Antioxidant and Antigenotoxic Actions of Gum Arabic on the Intestinal Mucosa, Liver and Bone Marrow of Swiss Mice Submitted to Colorectal Carcinogenesis

Colorectal carcinogenesis is characterized by oxidative stress and the formation of aberrant crypts in its initial stages. Gum arabic (GA) is a natural product with antioxidant properties, and, therefore, supposed antitumor action. The aim of this study was to evaluate the effects of GA on the formation of aberrant crypts, as well as the local, hepatic, and systemic genotoxicity and oxidative stress. We induced colorectal carcinogenesis in Swiss male mice, afterwards treated them with water, 2.5% GA or 5% GA via gavage for twelve weeks and then performed surgery in order to obtain samples to analysis (proximal and distal colon, liver, blood, and bone marrow). The number of aberrant crypts in the GA-treated animals was lower than in the control groups. Likewise, there was a decline of colonic, hepatic, and systemic genotoxicity and oxidative stress. These results reflect the antioxidant role of GA and may lead to the development of treatments that inhibit colorectal carcinogenesis.

Role of Stress-Survival Pathways and Transcriptomic Alterations in Progression of Colorectal Cancer: A Health Disparities Perspective

Every year, more than a million individuals are diagnosed with colorectal cancer (CRC) across the world. Certain lifestyle and genetic factors are known to drive the high incidence and mortality rates in some groups of individuals. The presence of enormous amounts of reactive oxygen species is implicated for the on-set and carcinogenesis, and oxidant scavengers are thought to be important in CRC therapy. In this review, we focus on the ethnicity-based CRC disparities in the U.S., the negative effects of oxidative stress and apoptosis, and gene regulation in CRC carcinogenesis. We also highlight the use of antioxidants for CRC treatment, along with screening for certain regulatory genetic elements and oxidative stress indicators as potential biomarkers to determine the CRC risk and progression.

Tobacco Smoking and the Fecal Microbiome in a Large, Multi-ethnic Cohort

BACKGROUND

Increasing evidence suggests that tobacco smoking, a well-known driver of carcinogenesis, influences the gut microbiome; however, these relationships remain understudied in diverse populations. Thus, we performed an analysis of smoking and the gut microbiome in a subset of 803 adults from the multi-ethnic NYU FAMiLI study.

METHODS

We assessed fecal microbiota using 16S rRNA gene sequencing, and clustered samples into Amplicon Sequence Variants using QIIME2. We evaluated inferred microbial pathway abundance using PICRUSt. We compared population β-diversity, and relative taxonomic and functional pathway abundance, between never smokers, former smokers, and current smokers.

RESULTS

We found that the overall composition of the fecal microbiome in former and current smokers differs significantly from that of never smokers. The taxa Prevotella and Veillonellaceae were enriched in current and former smokers, whereas the taxa Lachnospira and Tenericutes were depleted, relative to never smokers. These shifts were consistent across racial and ethnic subgroups. Relative to never smokers, the abundance of taxa enriched in current smokers were positively correlated with the imputed abundance of pathways involving smoking-associated toxin breakdown and response to reactive oxygen species (ROS).

CONCLUSIONS

Our findings suggest common mechanisms of smoking associated microbial change across racial subgroups, regardless of initial microbiome composition. The correlation of these differentials with ROS exposure pathways may suggest a role for these taxa in the known association between smoking, ROS and carcinogenesis.

IMPACT

Smoking shifts in the microbiome may be independent of initial composition, stimulating further studies on the microbiome in carcinogenesis and cancer prevention.

Dietary and Lifestyle Oxidative Balance Scores and Incident Colorectal Cancer Risk among Older Women; the Iowa Women's Health Study

BACKGROUND

Basic science literature strongly supports a role of oxidative stress in colorectal cancer (CRC) etiology, but in epidemiologic studies, associations of most individual exposures with CRC have been weak or inconsistent. However, recent epidemiologic evidence suggests that the collective effects of these exposures on oxidative balance and CRC risk may be substantial.

METHODS

Using food frequency and lifestyle questionnaire data from the prospective Iowa Women's Health Study (1986-2012), we investigated associations of 11-component dietary and 4-component lifestyle oxidative balance scores (OBS) with incident CRC using multivariable Cox proportional hazards regression.

RESULTS

Of the 33,736 cancer-free women aged 55-69 years at baseline, 1,632 developed CRC during follow-up. Among participants in the highest relative to the lowest dietary and lifestyle OBS quintiles (higher anti-oxidant relative to pro-oxidant exposures), the adjusted hazard ratios (HRs) and their 95% confidence intervals (CI) were, respectively, 0.77 (0.63, 0.94) (P_trend=0.02) and 0.61 (0.52, 0.71) (P_trend<0.0001). Among those in the highest relative to the lowest joint lifestyle/dietary OBS quintile, the HR was 0.45 (95% CI 0.26, 0.77).

CONCLUSIONS

Our findings suggest that a predominance of antioxidant over pro-oxidant dietary and lifestyle exposures-separately and especially jointly-may be inversely associated with CRC risk among older women.

Experimental Evaluation of the Effectiveness of Resveratrol as an Antioxidant in Colon Cancer Prevention

According to the WHO, cancer is the second leading cause of death globally and the third most common cancer is colorectal. A significant etiological factor for carcinogenesis might be oxidative stress. Chemoprevention by consuming natural antioxidants has great perspectives in the struggle to control cancer because it is available and affordable for the wide population. Studies by diverse research groups discovered that grapes, as well as grape-based products, are exceptional sources of the polyphenolic compound resveratrol, which has powerful antioxidant properties. Despite the great number of publications on the anticancer effectiveness of resveratrol, they were all aimed at studying its action once the condition was established. This experiment was the first to study the dynamics of the anticancer activity of resveratrol in the development of chemically induced colorectal cancer. Administrating resveratrol along with 1,2-dimethylhydrazine (DMH) during 30 weeks led to the inhibition of oxidative stress manifestations, in particular, lipid peroxidation. Our research showed that the level of thiobarbituric acid reactive substances in blood serum was 85.1%, 214.6%, and 276.9% lower on the third, fifth, and seventh months of the experiment in the group of rats that obtained resveratrol, compared with the animals affected only by DMH. In the fifth month of the experiment, we noticed that the GPx activity in blood serum was 1.54 times higher than the DMH-control level. During the next 8 weeks, this indicator decreased. The activity of glutathione reductase increased by 2 times in the seventh month, compared with the DMH-control. Histologically resveratrol decelerated the development of the tumor. After 30 weeks of experiment, rats that were receiving only DMH had developed colon adenocarcinoma in situ. In contrast to them, morphological changes in the colon tissue of the animals that obtained resveratrol + DMH could be characterized as signs of mucous colitis.

Pro-Oxidant Therapeutic Activities of Cerium Oxide Nanoparticles in Colorectal Carcinoma Cells

Given that basal levels of reactive oxygen species (ROS) are higher in cancer cells, there is a growing school of thought that endorses pro-oxidants as potential chemotherapeutic agents. Intriguingly, cerium oxide (CeO2) nanoparticles can manifest either anti- or pro-oxidant activity as a function of differential pH of various subcellular localizations. In an acidic pH environment, for example, in extracellular milieu of cancer cells, CeO2 would function as a pro-oxidant. Based on this concept, the present study is designed to investigate the pro-oxidant activities of CeO2 in human colorectal carcinoma cell line (HCT 116). For comparison, we have also studied the effect of ceria nanoparticles on human embryonic kidney (HEK 293) cells. Dose-dependent viability of cancerous as well as normal cells has been assessed by treating them independently with CeO2 nanoparticles of different concentrations (5-100 μg/mL) in the culture media. The half maximal inhibitory concentration (IC50) of nanoceria for HCT 116 is found to be 50.48 μg/mL while that for the HEK 293 cell line is 92.03 μg/mL. To understand the intricate molecular mechanisms of CeO2-induced cellular apoptosis, a series of experiments have been conducted. The apoptosis-inducing ability of nanoceria has been investigated by Annexin V-FITC staining, caspase 3/9 analysis, cytochrome c release, intracellular ROS analysis, and mitochondrial membrane potential analysis using flow cytometry. Experimental data suggest that CeO2 treatment causes DNA fragmentation through enhanced generation of ROS, which ultimately leads to cellular apoptosis through the p53-dependent mitochondrial signaling pathway.

Dietary probiotic and metabolites improve intestinal homeostasis and prevent colorectal cancer

Metabolites from Lactobacillus casei display substantial antioxidant and anti-inflammatory activities, inhibit colorectal cancer cell proliferation and growth, and modulate gut microfloral composition, specifically reducing sulfidogenic bacteria.

Senescence-associated tissue microenvironment promotes colon cancer formation through the secretory factor GDF15

The risk of colorectal cancer (CRC) varies between people, and the cellular mechanisms mediating the differences in risk are largely unknown. Senescence has been implicated as a causative cellular mechanism for many diseases, including cancer, and may affect the risk for CRC. Senescent fibroblasts that accumulate in tissues secondary to aging and oxidative stress have been shown to promote cancer formation via a senescence-associated secretory phenotype (SASP). In this study, we assessed the role of senescence and the SASP in CRC formation. Using primary human colon tissue, we found an accumulation of senescent fibroblasts in normal tissues from individuals with advanced adenomas or carcinomas in comparison with individuals with no polyps or CRC. In in vitro and ex vivo model systems, we induced senescence using oxidative stress in colon fibroblasts and demonstrated that the senescent fibroblasts secrete GDF15 as an essential SASP factor that promotes cell proliferation, migration, and invasion in colon adenoma and CRC cell lines as well as primary colon organoids via the MAPK and PI3K signaling pathways. In addition, we observed increased mRNA expression of GDF15 in primary normal colon tissue from people at increased risk for CRC in comparison with average risk individuals. These findings implicate the importance of a senescence-associated tissue microenvironment and the secretory factor GDF15 in promoting CRC formation.

Cigarette smoke extract modulates E-Cadherin, Claudin-1 and miR-21 and promotes cancer invasiveness in human colorectal adenocarcinoma cells

BACKGROUND

Cigarette smoke is considered a risk factor for lung and colorectal cancer. A convincing link between epithelial-to-mesenchymal transition (EMT) with colorectal cancer progression and therapeutic resistance has emerged. Deregulated expression of E-Cadherin and Claudin-1 and increased miR-21 expression and invasiveness represent hallmarks of EMT. The effects of cigarette smoke exposure on EMT in colorectal adenocarcinoma cells are largely unknown.

AIM

The aim of the study is to evaluate the effect of cigarette smoke extract (CSE) on miR-21, Claudin-1 and E-Cadherin, molecules associated to EMT in colorectal cancer cells.

METHODS

A human colorectal adenocarcinoma cell line (Caco-2) was treated with CSE at different concentration (5% and 10%) and for different time points (3 h and 24 h). Metabolic activity (by MTS assay), cell necrosis/cell apoptosis (evaluating Propidium Iodide/Annexin V expression by flow cytometry), miR-21, Claudin-1 and E-Cadherin gene expression were evaluated by Real time PCR. Cell permeability, actin polymerization and cancer cell migration was assessed by Trans-Epitelial Electrical Resistance (TEER), Phalloidin expression and matrigel system, respectively.

RESULTS

CSE at all the tested concentrations and at all time points reduced cell necrosis. CSE at 10% increased miR-21 and reduced the metabolic activity, cell necrosis, Claudin-1 and E-cadherin mRNA at 3 h. Cell permeability, actin polymerization and cancer cell migration were all increased upon CSE exposure.

CONCLUSION

These results showed that CSE increasing miR-21, Claudin-1 and E-Cadherin and enhancing the aggressiveness of cancer cells, may concur to colorectal cancer progression.

Untargeted lipidomic features associated with colorectal cancer in a prospective cohort

BACKGROUND

Epidemiologists are beginning to employ metabolomics and lipidomics with archived blood from incident cases and controls to discover causes of cancer. Although several such studies have focused on colorectal cancer (CRC), they all followed targeted or semi-targeted designs that limited their ability to find discriminating molecules and pathways related to the causes of CRC.

METHODS

Using an untargeted design, we measured lipophilic metabolites in prediagnostic serum from 66 CRC patients and 66 matched controls from the European Prospective Investigation into Cancer and Nutrition (Turin, Italy). Samples were analyzed by liquid chromatography-high-resolution mass spectrometry (LC-MS), resulting in 8690 features for statistical analysis.

RESULTS

Rather than the usual multiple-hypothesis-testing approach, we based variable selection on an ensemble of regression methods, which found nine features to be associated with case-control status. We then regressed each selected feature on time-to-diagnosis to determine whether the feature was likely to be either a potentially causal biomarker or a reactive product of disease progression (reverse causality).

CONCLUSIONS

Of the nine selected LC-MS features, four appear to be involved in CRC etiology and merit further investigation in prospective studies of CRC. Four other features appear to be related to progression of the disease (reverse causality), and may represent biomarkers of value for early detection of CRC.

THE RELATIONSHIP BETWEEN SERUM LEVEL OF MALONDIALDEHYDE AND PROGRESSION OF COLORECTAL CANCER

SUMMARY – The purpose of the study was to assess the level of serum malondialdehyde (MDA) concentration and its association with the stage and histopathologic sizes of colorectal cancer (CRC). One hundred and two patients having undergone surgical treatment of CRC between January 2014 and December 2015 were included in this cross-sectional study. The patients were divided into four groups (stage I-IV) according to the TNM classification. Control group included 30 subjects with no signs of malignancy and inflammatory diseases. In each patient, preoperative blood samples were obtained for determination of MDA concentration by ELISA immunoassay. Serum levels of MDA were progressively increased in patients with CRC, reaching the highest value in the fourth stage of CRC. Serum concentrations of MDA were significantly higher in pT4 group as compared with pT3 and pT2 groups of CRC patients (p<0.01). Significantly higher levels of MDA were found in the N1 and N2 groups of CRC patients as compared with N0 group, as well as in patients with metastatic disease as compared with those without metastasis (p<0.001). In conclusion, the progression of CRC is associated with a significant increase in serum MDA levels.

Protective Role of Carbonic Anhydrases III and VII in Cellular Defense Mechanisms upon Redox Unbalance

Under oxidative stress conditions, several constitutive cellular defense systems are activated, which involve both enzymatic systems and molecules with antioxidant properties such as glutathione and vitamins. In addition, proteins containing reactive sulfhydryl groups may eventually undergo reversible redox modifications whose products act as protective shields able to avoid further permanent molecular oxidative damage either in stressful conditions or under pathological circumstances. After the recovery of normal redox conditions, the reduced state of protein sulfhydryl groups is restored. In this context, carbonic anhydrases (CAs) III and VII, which are human metalloenzymes catalyzing the reversible hydration of carbon dioxide to bicarbonate and proton, have been identified to play an antioxidant role in cells where oxidative damage occurs. Both proteins are mainly localized in tissues characterized by a high rate of oxygen consumption, and contain on their molecular surface two reactive cysteine residues eventually undergoing S-glutathionylation. Here, we will provide an overview on the molecular and functional features of these proteins highlighting their implications into molecular processes occurring during oxidative stress conditions.

Antioxidant and Anticancer Activities of Essential Oil from Gannan Navel Orange Peel

China is one of the leading producers of citrus in the world. Gannan in Jiangxi Province is the top navel orange producing area in China. In the present study, an essential oil was prepared by cold pressing of Gannan navel orange peel followed by molecular distillation. Its chemical composition was analyzed by GC-MS. Twenty four constituents were identified, representing 97.9% of the total oil. The predominant constituent was limonene (74.6%). The anticancer activities of this orange essential oil, as well as some of its major constituents, were investigated by MTT assay. This essential oil showed a positive effect on the inhibition of the proliferation of a human lung cancer cell line A549 and prostate cancer cell line 22RV-1. Some of the oil constituents displayed high anticancer potential and deserve further study.

Fish Oil Contaminated with Persistent Organic Pollutants Induces Colonic Aberrant Crypt Foci Formation and Reduces Antioxidant Enzyme Gene Expression in Rats

Background: Epidemiologic, clinical, and experimental studies have suggested that fish oil (FO), a rich source of n-3 (ω-3) polyunsaturated fatty acids, protects against colon cancer. However, this message is confounded by the FDA's warning that the consumption of certain types of fish should be restricted because of contamination with persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and organochlorine pesticides.Objective: We examined FO contaminated with POPs (PCBs, dichlorodiphenyltrichloroethane, and chlordane) compared with unmodified FO on the risk factors of colon cancer development.Methods: Male Sprague-Dawley rats aged 28 d (n = 30) were allocated into 3 groups and fed 15% corn oil (CO), FO, or POP-contaminated FO for 9 wk with a subcutaneous injection of colon carcinogen azoxymethane at weeks 3 and 4. Colonic aberrant crypt foci (ACF) and cell proliferation were enumerated, and the gene expression of inflammation, antioxidant enzymes, and repair enzymes were determined with the use of real-time quantitative polymerase chain reaction analysis.Results: FO-fed rats had a lower number of ACF (mean ± SE: 29 ± 4.0 for FO compared with 53 ± 8.4 for CO and 44 ± 4.6 for POP FO) and higher-multiplicity ACF than the CO and POP FO groups (4.7 ± 0.9 for FO compared with 11 ± 1.5 for CO and 9.6 ± 1.8 for POP FO) (P < 0.05). FO feeding lowered the proliferation index compared with the CO and POP FO feeding groups (18% ± 1.1% for FO compared with 25% ± 1.6% for CO and 23% ± 0.7% for POP FO) (P = 0.009). Superoxide dismutase [2.4 ± 0.6 relative quantification (RQ) for FO compared with 1.2 ± 0.2 RQ for CO and 1.3 ± 0.3 RQ for POP FO] and catalase gene expression (10 ± 2.0 RQ for FO compared with 5.4 ± 1.1 RQ for CO and 6.6 ± 1.5 RQ for POP FO) were higher in the FO group than in the CO and POP FO groups (P < 0.05). There were no differences between CO and POP FO on the variables.Conclusion: These results indicate that POPs in FO reduce the preventive effects of FO on colon carcinogenesis by increasing preneoplastic lesion formation through the downregulation of antioxidant enzyme expression and increasing cell proliferation in rats.

The association between Dietary Inflammatory Index scores and the prevalence of colorectal adenoma

Objective

The Dietary Inflammatory Index (DII)TM, which was developed to characterize the inflammatory potential of a person’s diet, has been shown to be associated with inflammatory conditions such as cancer. The present study aimed to investigate the association between DII scores and colorectal adenoma (CRA), a pre-cancerous condition.

Design

Responses to baseline dietary questionnaires were used calculate DII scores. In a cross-sectional study design, the association between DII scores and CRA prevalence was determined in men and women separately using logistic regression models.

Setting

Ten cancer screening centres across the USA.

Subjects

Participants were those included in the screening arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.

Results

Among the 44 278 individuals included in these analyses, men with diets in the most inflammatory quartile of DII scores had higher odds of all types of CRA (advanced, non-advanced and multiple (>1)) compared with those with diets in the least inflammatory quartile of DII scores. In fully adjusted models, compared with those with DII scores in quartile 1 (least inflammatory), males with DII scores in quartile 3 (adjusted odds ratio (aOR)=1·28; 95 % CI 1·12, 1·47) and quartile 4 (aOR=1·41; 95 % CI 1·23, 1·62) were more likely to have prevalent distal CRA. Higher DII scores, representing a more inflammatory diet, also were weakly associated with a higher prevalence of CRA in women.

Conclusions

Implementing an anti-inflammatory diet may be an effective means of primary prevention of CRA, especially in men.

α-Tocopheryl Succinate Affects Malignant Cell Viability, Proliferation, and Differentiation

The widespread occurrence of malignant tumors motivates great attention to finding and investigating effective new antitumor preparations. Such preparations include compounds of the vitamin E family. Among them, α-tocopheryl succinate (vitamin E succinate (VES)) has the most pronounced antitumor properties. In this review, various targets and mechanisms of the antitumor effect of vitamin E succinate are characterized. It has been shown that VES has multiple intracellular targets and effects, and as a result VES is able to induce apoptosis in tumor cells, inhibit their proliferation, induce differentiation, prevent metastasizing, and inhibit angiogenesis. However, VES has minimal effects on normal cells and tissues. Due to the variety of targets and selectivity of action, VES is a promising agent against malignant neoplasms. More detailed studies in this area can contribute to development of effective and safe chemotherapeutic preparations.

Main nutrient patterns and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition study

BACKGROUND

Much of the current literature on diet-colorectal cancer (CRC) associations focused on studies of single foods/nutrients, whereas less is known about nutrient patterns. We investigated the association between major nutrient patterns and CRC risk in participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

METHODS

Among 477 312 participants, intakes of 23 nutrients were estimated from validated dietary questionnaires. Using results from a previous principal component (PC) analysis, four major nutrient patterns were identified. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed for the association of each of the four patterns and CRC incidence using multivariate Cox proportional hazards models with adjustment for established CRC risk factors.

RESULTS

During an average of 11 years of follow-up, 4517 incident cases of CRC were documented. A nutrient pattern characterised by high intakes of vitamins and minerals was inversely associated with CRC (HR per 1 s.d.=0.94, 95% CI: 0.92-0.98) as was a pattern characterised by total protein, riboflavin, phosphorus and calcium (HR (1 s.d.)=0.96, 95% CI: 0.93-0.99). The remaining two patterns were not significantly associated with CRC risk.

CONCLUSIONS

Analysing nutrient patterns may improve our understanding of how groups of nutrients relate to CRC.

Insights into the role of reactive sulfhydryl groups of Carbonic Anhydrase III and VII during oxidative damage

Carbonic anhydrases (CAs) III and VII are two cytosolic isoforms of the α-CA family which catalyze the physiological reaction of carbon dioxide hydration to bicarbonate and proton. Despite these two enzymes share a 49% sequence identity and present a very similar three-dimensional structure, they show profound differences when comparing the specific activity for CO₂ hydration reaction, with CA VII being much more active than CA III. Recently, CA III and CA VII have been proposed to play a new role as scavenger enzymes in cells where oxidative damage occurs. Here, we will examine functional and structural features of these two isoforms giving insights into their newly proposed protective role against oxidative stress.

Evaluating Ultra-long-Chain Fatty Acids as Biomarkers of Colorectal Cancer Risk

BACKGROUND

Cross-sectional studies reported a novel set of hydroxylated ultra-long-chain fatty acids (ULCFA) that were present at significantly lower levels in colorectal cancer cases than controls. Follow-up studies suggested that these molecules were potential biomarkers of protective exposure for colorectal cancer. To test the hypothesis that ULCFAs reflect causal pathways, we measured their levels in prediagnostic serum from incident colorectal cancer cases and controls.

METHODS

Serum from 95 colorectal cancer patients and 95 matched controls was obtained from the Italian arm of the European Prospective Investigation into Cancer and Nutrition cohort and analyzed by liquid chromatography-high-resolution mass spectrometry. Levels of 8 ULCFAs were compared between cases and controls with paired t tests and a linear model that used time to diagnosis (TTD) to determine whether case-control differences were influenced by disease progression.

RESULTS

Although paired t tests detected significantly lower levels of four ULCFAs in colorectal cancer cases, confirming earlier reports, the case-control differences diminished significantly with increasing TTD (7 days-14 years).

CONCLUSION

Levels of several ULCFAs were lower in incident colorectal cancer cases than controls. However, because case-control differences decreased with increasing TTD, we conclude that these molecules were likely consumed by processes related to cancer progression rather than causal pathways.

IMPACT

ULCFA levels are unlikely to represent exposures that protect individuals from colorectal cancer. Future research should focus on the diagnostic potential and origins of these molecules. Our use of TTD as a covariate in a linear model provides an efficient method for distinguishing causal and reactive biomarkers in biospecimens from prospective cohorts. Cancer Epidemiol Biomarkers Prev; 25(8); 1216-23. ©2016 AACR.

An Inducible, Large-Intestine-Specific Transgenic Mouse Model for Colitis and Colitis-Induced Colon Cancer Research

BACKGROUND

Animal models are an important tool to understand intestinal biology. Our laboratory previously generated C57BL/6-Tg(Car1-cre)5Flt transgenic mice (CAC) with large-intestine-specific Cre recombinase (Cre) expression as a model to study colon health.

AIM

To expand the utility of the CAC mouse model by determining the impact of chemically induced colitis on CAC transgene expression.

METHODS

CAC mice were crossed to Rosa reporter mice (Rosa26R (flox/flox) ) with a lox-STOP-lox signal controlling β-galactosidase (βgal) expression and then further crossed with Apc(CKO/CKO) mice in some experiments to delete Apc alleles (Apc (Δ580) ). Initially, 8-week-old CAC(Tg/WT);Rosa26R (flox/WT) ;Apc (Δ580/WT) mice were treated with dextran sulfate sodium (DSS) in drinking water (5 days, 0, 0.65, 1.35, or 2.0 %). Colon tissue damage and βgal labeling were analyzed 10 day after stopping DSS. Next, 8-week-old CAC(Tg/WT);Rosa26R(flox/flox) mice were treated with 0 or 1.35 % DSS, and colonic βgal labeling was assessed at 30 day post-DSS treatment. Finally, 10-week-old CAC(Tg/WT);Apc (Δ580/WT) mice were treated with DSS (0 or 2 %) for 5 days and colonic tumors were analyzed at 20 weeks.

RESULTS

CAC(Tg/WT);Rosa26R (flox/WT) ;Apc (Δ580/WT) mice had a DSS dose-dependent increase in colon epithelial damage that correlated with increased epithelial βgal labeling at 10 days (r (2) = 0.9, β = 0.75). The βgal labeling in CAC(Tg/WT);Rosa26R(flox/flox) mice colon remained high at 30 days, especially in the crypts of the healed ulcer. DSS also increased colon tumor incidence and multiplicity in CAC(Tg/WT);Apc (Δ580/WT) mice.

CONCLUSIONS

DSS-mediated epithelial damage induces a persistent, Cre-mediated recombination of floxed alleles in CAC mice. This enables the examination of gene function in colon epithelium during experimental colitis and colitis-induced colon cancer.

Dietary antioxidant capacity and all-cause and cause-specific mortality in the E3N/EPIC cohort study

PURPOSE

The cellular oxidative stress (balance between pro-oxidant and antioxidant) may be a major risk factor for chronic diseases. Antioxidant capacity of human diet can be globally assessed through the dietary non-enzymatic antioxidant capacity (NEAC). Our aim was to investigate the relationship between the NEAC and all-cause and cause-specific mortality, and to test potential interactions with smoking status, a well-known pro-oxidant factor.

METHODS

Among the French women of the E3N prospective cohort study initiated in 1990, including 4619 deaths among 1,199,011 persons-years of follow-up. A validated dietary history questionnaire assessed usual food intake; NEAC intake was estimated using a food composition table from two different methods: ferric ion reducing antioxidant power (FRAP) and total radical-trapping antioxidant parameter (TRAP). Hazard ratio (HR) estimates and 95 % confidence intervals (CI) were derived from Cox proportional hazards regression models.

RESULTS

In multivariate analyses, FRAP dietary equivalent intake was inversely associated with mortality from all-causes (HR for the fourth vs. the first quartile: HR₄ = 0.75, 95 % CI 0.67, 0.83, p _trend < 0.0001), cancer, and cardiovascular diseases. Similar results were obtained with TRAP. There was an interaction between NEAC dietary equivalent intake and smoking status for all-cause and cardiovascular disease mortality, but not cancer mortality (respectively, for FRAP, p _inter = 0.002; 0.013; 0.113, results were similar with TRAP), and the association was the strongest among current smokers.

CONCLUSION

This prospective cohort study highlights the importance of antioxidant consumption for mortality prevention, especially among current smokers.

Prognostic value of carbonic anhydrase VII expression in colorectal carcinoma

BACKGROUND

Carbonic anhydrases (CAs) have been implicated in the pathogenesis of human cancers. Carbonic anhydrase VII (CA7), a member of the CA gene family, was recently demonstrated to be expressed in several human tissues including colon. Nevertheless, the expression and clinical relevance of CA7 in colorectal carcinoma (CRC) has not been investigated.

METHODS

Real-time PCR, western blot, and immunohistochemistry analyses were used to determine CA7 expression in CRC clinical samples. The correlation of CA7 expression with clinicopathologic features was assessed in 228 patients from Luoyang, China (training cohort) and validated in 151 patients from Shanghai, China (validation cohort). Kaplan-Meier and Cox proportional regression analyses were used to estimate the association between CA7 expression and patients' survival.

RESULTS

CA7 expression was frequently downregulated in CRC tissues at both the mRNA and protein levels. Reduced expression of CA7 was significantly correlated with poor differentiation, positive lymph node metastasis, advanced TNM stage and unfavorable clinical outcome not only in the training cohort but also in the validation set. Survival analysis indicated that patients with lower CA7 expression had a significantly shorter disease-specific survival (DSS) than those with higher CA7 expression. Importantly, further stage-based analyses revealed that decreased CA7 expression significantly predicted poor DSS and was an independent adverse prognostic indicator for patients with early stage tumors in both cohorts.

CONCLUSIONS

Our results indicate that decreased expression of CA7 correlates with disease progression and predicts poor prognosis in CRC, especially for patients with early stage tumors.

The shifting perception on antioxidants: the case of vitamin E and β-carotene

Antioxidants are vital for aerobic life, and for decades the expectations of antioxidants as health promoting agents were very high. However, relatively recent meta-analyses of clinical studies show that supplementation of antioxidants does not result in the presumed health benefit, but is associated with increased mortality. The dilemma that still needs to be solved is: what are antioxidants in the end, healthy or toxic? We have evaluated this dilemma by examining the presumed health effects of two individual antioxidants with opposite images i.e. the “poisonous” β-carotene and the “wholesome” vitamin E and focused on one aspect, namely their role in inducing BPDE-DNA adducts. It appears that both antioxidants promote DNA adduct formation indirectly by inhibition of the protective enzyme glutathione-S-transferase π (GST π). Despite their opposite image, both antioxidants display a similar type of toxicity. It is concluded that, in the appreciation of antioxidants, first their benefits should be identified and substantiated by elucidating their molecular mechanism. Subsequently, the risks should be identified including the molecular mechanism. The optimal benefit–risk ratio has to be determined for each antioxidant and each individual separately, also considering the dose.

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To date, the debate on the health benefit of antioxidants continues.

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The effect of vitamin E and β-carotene on BPDE-DNA adduct formation was evaluated.

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Both antioxidants promote DNA adduct formation by inhibition of GST π.

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Accurate benefit–risk analyses give a balanced view on the effects of antioxidants.