Use of HT-29, a cultured human colon cancer cell line, to study the effect of fermented milks on colon cancer cell growth and differentiation

Probiotic immunonutrition impacts on colon cancer immunotherapy and prevention

The important role of the immune system in treating cancer has attracted the attention of researchers to the emergence of oncology research. Immunotherapy has shown that the immune system is important in the fight against cancer. The challenge has led researchers to analyze the impact of immunotherapy on improving the status of the immune system, modifying the resulting safety response, reducing toxicity, and improving the results. This study aimed to discuss the potential mechanisms of probiotics in preventing colon cancer. The mechanisms include the change in intestinal microbiota, the metabolic activity of microbiota, the binding and degradation of the carcinogenic compounds present in the lumen of the intestine, the production of compounds with anticancer activity, immune system modification, intestinal dysfunction, changes in host physiology, and inhibition of cell proliferation and induction of apoptosis in cancerous cells. By contrast, very few reports have shown the harmful effects of oral probiotic supplements. According to available evidence, further studies on probiotics are needed, especially in identifying bacterial species with anticancer potential, studying the survival of the strains after passing the digestive tract, reviewing potential side effects in people with a weak immune system, and ultimately consuming and repeating its use. This study emphasizes that the nutritional formula can modulate inflammatory and immune responses in cancer patients. This effect reduces acute toxicity, although the pathways and measurement of this immune response are unclear. Nutrition safety is an emerging field in oncology, and further research is required.

Discovery of 8-(6-Methoxypyridin-3-yl)-1-(4-(piperazin-1-yl)-3-(trifluoromethyl)phenyl)-1,5-dihydro-4H-[1,2,3]triazolo[4,5-c]quinolin-4-one (CQ211) as a Highly Potent and Selective RIOK2 Inhibitor

RIOK2 is an atypical kinase implicated in multiple human cancers. Although recent studies establish the role of RIOK2 in ribosome maturation and cell cycle progression, its biological functions remain poorly elucidated, hindering the potential to explore RIOK2 as a therapeutic target. Here, we report the discovery of CQ211, the most potent and selective RIOK2 inhibitor reported so far. CQ211 displays a high binding affinity (K_d = 6.1 nM) and shows excellent selectivity to RIOK2 in both enzymatic and cellular studies. It also exhibits potent proliferation inhibition activity against multiple cancer cell lines and demonstrates promising in vivo efficacy in mouse xenograft models. The crystal structure of RIOK2-CQ211 sheds light on the molecular mechanism of inhibition and informs the subsequent optimization. The study provides a cell-active chemical probe for verifying RIOK2 functions, which may also serve as a leading molecule in the development of therapeutic RIOK2 inhibitors.

Probiotics, prebiotics and synbiotics: Safe options for next-generation therapeutics

Abstract

Probiotics have been considered as an economical and safe alternative for the treatment of a large number of chronic diseases and improvement of human health. They are known to modulate the host immunity and protect from several infectious and non-infectious diseases. The colonization, killing of pathogens and induction of host cells are few of the important probiotic attributes which affect several functions of the host. In addition, prebiotics and non-digestible food substances selectively promote the growth of probiotics and human health through nutrient enrichment, and modulation of gut microbiota and immune system. This review highlights the role of probiotics and prebiotics alone and in combination (synbiotics) in the modulation of immune system, treatment of infections, management of inflammatory bowel disease and cancer therapy.

Key points

• Probiotics and their derivatives against several human diseases.

• Prebiotics feed probiotics and induce several functions in the host.

• Discovery of novel and biosafe products needs attention for human health.

Chemical Compounds, Antitumor and Antimicrobial Activities of Dry Ethanol Extracts from Koelreuteria paniculata Laxm

Koelreuteria paniculata Laxm. is used in traditional medicine and has various established biological activities, however, the species is considered to be a potentially invasive alien tree species for Bulgarian flora. However, there is still much to be studied about the phytochemical and biological characteristics of the species. The present study aimed to determine the chemical composition of the ethanol extracts of aerial plant parts, by GC-MS analysis, and to thereby evaluate their in vitro antitumor and antibacterial properties. All three extracts were tested against the HT-29 and PC3 tumor cell lines using the MTT assay. Fifty-six components were identified from leaf, flower, and stem bark extracts, and over 10% were the following constituents: pyrogallol, α-terpinyl acetate, neryl acetate, and α-terpinyl isobutanoate. The oxygenated monoterpenes predominated in the extracts, followed by the oxygenated aliphatics and phenylpropanoids. Significant antiproliferative activity on the HT-29 cell line (IC₅₀-21.44 µg/mL and 23.63 µg/mL, respectively) was found for the flower and leaf extracts. Antibacterial activity was established for the following bacteria strains: Bacillus subtilis ATCC 6633, Bacillus cereus NCTC 10320, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 6027, and Proteus vulgaris ATCC 6380. The stem bark and flower extracts showed better antimicrobial potential. K. paniculata could be considered as a potential source of biologically active substances with antitumor and antibacterial properties.

Exploring the Role of Gut Microbiome in Colon Cancer

Dysbiosis of the gut microbiome has been associated with the development of colorectal cancer (CRC). Gut microbiota is involved in the metabolic transformations of dietary components into oncometabolites and tumor-suppressive metabolites that in turn affect CRC development. In a healthy colon, the major of microbial metabolism is saccharolytic fermentation pathways. The alpha-bug hypothesis suggested that oncogenic bacteria such as enterotoxigenic Bacteroides fragilis (ETBF) induce the development of CRC through direct interactions with colonic epithelial cells and alterations of microbiota composition at the colorectal site. Escherichia coli, E. faecalis, F. nucleatum, and Streptococcus gallolyticus showed higher abundance whereas Bifidobacterium, Clostridium, Faecalibacterium, and Roseburia showed reduced abundance in CRC patients. The alterations of gut microbiota may be used as potential therapeutic approaches to prevent or treat CRC. Probiotics such as Lactobacillus and Bifidobacterium inhibit the growth of CRC through inhibiting inflammation and angiogenesis and enhancing the function of the intestinal barrier through the secretion of short-chain fatty acids (SCFAs). Crosstalk between lifestyle, host genetics, and gut microbiota is well documented in the prevention and treatment of CRC. Future studies are required to understand the interaction between gut microbiota and host to the influence and prevention of CRC. However, a better understanding of bacterial dysbiosis in the heterogeneity of CRC tumors should also be considered. Metatranscriptomic and metaproteomic studies are considered a powerful omic tool to understand the anti-cancer properties of certain bacterial strains. The clinical benefits of probiotics in the CRC context remain to be determined. Metagenomic approaches along with metabolomics and immunology will open a new avenue for the treatment of CRC shortly. Dietary interventions may be suitable to modulate the growth of beneficial microbiota in the gut.

Anti-cancer effects of Bifidobacterium species in colon cancer cells and a mouse model of carcinogenesis

INTRODUCTION

Probiotics are suggested to prevent colorectal cancer (CRC). This study aimed to investigate the anticancer properties of some potential probiotics in vitro and in vivo.

MATERIALS AND METHODS

Anticancer effects of the following potential probiotic groups were investigated in LS174T cancer cells compared to IEC-18 normal cells. 1. a single strain of Bifidobacterium. breve, 2. a single strain of Lactobacillus. reuteri, 3. a cocktail of 5 strains of Lactobacilli (LC), 4. a cocktail of 5 strains of Bifidobacteria (BC), 5. a cocktail of 10 strains from Lactobacillus and Bifidobacterium (L+B). Apoptosis rate, EGFR, HER-2 and PTGS-2 (COX-2 protein) expression levels were assessed as metrics of evaluating anticancer properties. Effect of BC, as the most effective group in vitro, was further assessed in mice models.

RESULTS

BC induced ~21% and only ~3% apoptosis among LS174T and IEC-18 cells respectively. BC decreased the expression of EGFR by 4.4 folds, HER-2 by 6.7 folds, and PTGS-2 by 20 folds among the LS174T cells. In all these cases, BC did not interfere significantly with the expression of the genes in IEC-18 cells. This cocktail has caused only 1.1 folds decrease, 1.8 folds increase and 1.7 folds decrease in EGFR, HER-2 and PTGS-2 expression, respectively. Western blot analysis confirmed these results in the protein level. BC significantly ameliorated the disease activity index, restored colon length, inhibited the increase in incidence and progress of tumors to higher stages and grades.

CONCLUSIONS

BC was the most efficient treatment in this study. It had considerable "protective" anti-cancer properties and concomitantly down regulated EGFR, HER-2 and PTGS-2 (COX-2), while having significant anti-CRC effects on CRC mice models. In general, this potential probiotic could be considered as a suitable nutritional supplement to treat and prevent CRC.

Anticancer and Antimigration Effects of a Combinatorial Treatment of 5-Fluorouracil and Lactobacillus paracasei subsp. paracasei NTU 101 Fermented Skim Milk Extracts on Colorectal Cancer Cells

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Metabolites of lactic acid bacteria (LAB) have anticancer and antimetastasis capacities. This study aimed to investigate the chemotherapeutic effects of Lactobacillus paracasei subsp. paracasei NTU 101-fermented skim milk (NTU101-FM) extracts in combination with the chemotherapeutic drug 5-fluorouracil (5-FU) in a cellular CRC model. The NTU101-FM extracts effectively reduced CRC cell viability but were not cytotoxic to colon epithelial cells. Moreover, they increased RAW 264.7 cell viability. Notably, the cell viability of CRC cells was decreased by 5-FU in combination with the NTU101-FM extracts; the combinatorial treatment inhibited cell viability significantly more than 5-FU alone ( p < 0.05). An ethanol extract of NTU101-FM effectively attenuated CT26 cell migration. In conclusion, the ethanol extract prepared from NTU101-FM has a potential application as an anticancer agent in CRC.

Inhibitory Effects of Probiotic Lactobacillus on the Growth of Human Colonic Carcinoma Cell Line HT-29

This study was conducted to investigate the inhibitory effect of Lactobacillus cells and supernatants on the growth of the human colon cancer cell line HT-29. Our study results indicated that the PM153 strain exhibits the best adhesion ability and the highest survival in the gastrointestinal tract simulation experiment. Furthermore, after an 8-h co-culture of PM153 and HT-29 cells, the PM153 strain can induce the secretion of nitric oxide from the HT-29 cells. In addition, after the co-culture of the BCRC17010 strain (10⁸ cfu/mL) and HT-29 cells, the Bax/Bcl-2 ratio in the HT-29 cells was 1.19, which showed a significant difference from the other control and LAB groups (p < 0.05), which therefore led to the inference that the BCRC17010 strain exerts a pro-apoptotic effect on the HT-29 cells. Upon co-culture with HT-29 cells for 4, 8 and 12 h, the BCRC14625 strain (10⁸ cfu/mL) demonstrated a significant increase in lactate dehydrogenase (LDH) activity (p < 0.05), causing harm to the HT-29 cell membrane; further, after an 8-h co-culture with the HT-29 cells, it induced the secretion of nitric oxide (NO) from the HT-29 cells. Some lactic acid bacteria (LAB) strains have ability to inhibit the growth of the colorectal cancer cell line HT-29 Bax/Bcl-2 pathway or NO production. In summary, we demonstrated that the BCRC17010 strain, good abilities of adhesion and increased LDH release, was the best probiotic potential for inhibition of HT-29 growth amongst the seven LAB strains tested in vitro.

Effect of pulsed electric fields - assisted extraction on anti-inflammatory and cytotoxic activity of brown rice bioactive compounds

The bioactive compounds of brown rice exhibit many beneficial health effects, ranging from antioxidant to cytotoxic activities. Pulsed Electric Field (PEF) pretreatment can significantly enhance their extraction, through the induction of the electro-permeabilization of the cell membranes. This paper aims to demonstrate that PEF-assisted extraction of brown rice enables not only enhanced yields of antioxidant compounds, such as γ-oryzanol, polyphenols and phenolic acids, and of saturated and unsaturated fatty acids, but also increased cytotoxic effects on cancer cells. Initially, the PEF-assisted extraction conditions have been defined by the assessment of the cell permeabilization index via impedance measurements and the DPPH antioxidant activity. Subsequently, the biological effects of PEF have been evaluated on the cytotoxicity and anti-inflammatory properties against human colon cancer cell line HT29. The results show that PEF-assisted extraction, enhancing the yield of bioactive compounds, with respect to untreated extracts, significantly promotes their antioxidant activity, which is correlated with an increased HT29 cells cytotoxicity. In addition, PEF extracts of brown rice substantially inhibit also gene expression and interleukin production in colon cancer cells, suggesting their exploitation as natural anti-inflammatory agents. The integration of PEF pretreatment in the solvent extraction process of bioactives from brown rice appears, therefore, as a promising practice to significantly enhance their biological activity.

Immunomodulatory effects of Lactobacillus strains: emphasis on their effects on cancer cells

Lactobacilli are a group of normal microbiota whose immunomodulatory effects have been known for a long time. Recently, they have gained more attention for their direct and indirect effects on cancer cells. Several cell line experiments, animal model studies as well as clinical trials have indicated their inhibitory effects on cancer initiation and progression. Different lactobacilli strains could modulate innate and adoptive immune system. Such effects have been documented in modulation of function of T cells, dendritic cells and macrophages as well as cytokine production. In this review, the various immunomodulatory effects of lactobacilli on tumor cells as well as their direct cytotoxic effects on cancer cells are discussed.

Mechanisms and therapeutic effectiveness of lactobacilli

The gut microbiome is not a silent ecosystem but exerts several physiological and immunological functions. For many decades, lactobacilli have been used as an effective therapy for treatment of several pathological conditions displaying an overall positive safety profile. This review summarises the mechanisms and clinical evidence supporting therapeutic efficacy of lactobacilli. We searched Pubmed/Medline using the keyword ‘Lactobacillus’. Selected papers from 1950 to 2015 were chosen on the basis of their content. Relevant clinical and experimental articles using lactobacilli as therapeutic agents have been included. Applications of lactobacilli include kidney support for renal insufficiency, pancreas health, management of metabolic imbalance, and cancer treatment and prevention. In vitro and in vivo investigations have shown that prolonged lactobacilli administration induces qualitative and quantitative modifications in the human gastrointestinal microbial ecosystem with encouraging perspectives in counteracting pathology-associated physiological and immunological changes. Few studies have highlighted the risk of translocation with subsequent sepsis and bacteraemia following probiotic administration but there is still a lack of investigations on the dose effect of these compounds. Great care is thus required in the choice of the proper Lactobacillus species, their genetic stability and the translocation risk, mainly related to inflammatory disease-induced gut mucosa enhanced permeability. Finally, we need to determine the adequate amount of bacteria to be delivered in order to achieve the best clinical efficacy decreasing the risk of side effects.

Orally delivered microencapsulated probiotic formulation favorably impacts polyp formation in APC (Min/+) model of intestinal carcinogenesis

The development of intestinal polyps in an orthotopic colorectal mouse model, receiving a probiotic yogurt formulation containing microencapsulated live Lactobacillus acidophilus cells was investigated. The expression of various immunohistochemical markers namely CD8, Mac-1, Ki-67, and cleaved caspase-3, was evaluated. Results suggest that the probiotic formulation decreases overall intestinal inflammation. Mice receiving the probiotic formulation were found to develop almost two-fold fewer tumors in the small intestines. In the large intestine, however, there was no significant difference observed among polyp numbers. The formulation appears to have potential application in the prevention of various GI pathological conditions.

Iodine-125 induces apoptosis via regulating p53, microvessel density, and vascular endothelial growth factor in colorectal cancer

Background

Iodine interstitial brachytherapy has been widely reported for treating colorectal cancer (CRC). However, the inhibitory molecular mechanism of iodine-125 (I-125) on CRC has not been reported.

Methods

To illustrate the inhibitory mechanism of iodine-125 (I-125) on CRC, we established the animal models of CRC via the injection of HCT-8 cells into nude mice. Subsequently, the I-125 granules were implanted into the tumor of the animal model at different dosages. Proliferating cell nuclear antigen and terminal transferase dUTP nick end labeling were used to detect the apoptosis of the tumor cells. Immunohistochemistry SP staining was used to measure the expression of p53 protein. The protein levels were examined with western blot and ELISA. Meanwhile, microvessel density (MVD) was counted by endothelial cells immunostained by anti-CD34 antibody.

Results

The results showed that I-125 protests against CRC via increasing the protein level of p53 and decreasing the level of vascular endothelial growth factor (VEGF), leading to the decrease of MVD in CRC (P <0.0001). An effective inhibition dosage of I-125 ranged from 0.4 to 0.8 mCi.

Conclusions

The inhibitory mechanisms of iodine on CRC acted through an increase in the level of p53 and a decrease in the level of VEGF, resulting in a decrease of MVD.

Gastrointestinal cancers: influence of gut microbiota, probiotics and prebiotics

Cancers of the gastrointestinal (GI) tract continue to represent a major health problem, despite progress in therapy. Gut microbiota is a key element related to the genesis of GI cancers, countless papers addressing this burning issue across the world. We provide an updated knowledge of the involvement of gut microbiota in GI tumorigenesis, including its underlying mechanisms. We present also a comprehensive review of the evidence from animal and clinical studies using probiotics and/or prebiotics in the prevention and/or therapy of GI tumours, of GI cancer therapy-related toxicity and of post-operative complications. We summarize the anticarcinogenic mechanisms of these biotherapeutics from in vitro, animal and clinical interventions. More research is required to reveal the interactions of microflora with genetic, epigenetic and immunologic factors, diet and age, before any firm conclusion be drawn. Well-designed, randomized, double blind, placebo-controlled human studies using probiotics and/or prebiotics, with adequate follow-up are necessary in order to formulate directions for prevention and therapy.

Intestinal microbiota, probiotics and human gastrointestinal cancers

INTRODUCTION

Cancers of the gastrointestinal tract account for 25 % of all cancers and for 9 % of all causes of cancer death in the world, so gastrointestinal cancers represent a major health problem. In the past decades, an emerging role has been attributed to the interactions between the gastrointestinal content and the onset of neoplasia.

METHODS

Thus, exogenous microbial administration of peculiar bacterial strains (probiotics) has been suggested as having a profound influence on multiple processes associated with a change in cancer risk. Probiotics are mono or mixed cultures of live microorganisms that might beneficially affect the host by improving the characteristics of indigenous microflora. Although the effects of probiotic administration has been intensively investigated in vitro, in animal models, in healthy volunteers, and in some human gastrointestinal diseases, very little is still known about the possible cross-interactions among probiotic administration, changes of intestinal flora, and the neoplastic transformation of gastrointestinal mucosa.

RESULTS

Theoretically, probiotics are able to reduce cancer risk by a number of mechanisms: (a) binding and degradation of potential carcinogens; (b) quantitative, qualitative and metabolic alterations of the intestinal microflora; (c) production of anti-tumorigenic or anti-mutagenic compounds; (d) competitive action towards pathogenic bacteria; (e) enhancement of the host's immune response; (f) direct effects on cell proliferation.

CONCLUSION

This review will attempt to highlight the literature on the most widely recognized effects of probiotics against neoplastic transformation of gastrointestinal mucosa and in particular on their effects on cell proliferation.

Treating colon cancer with injectable PLGA-PEG-PLGA as a carrier for iodine-125

PURPOSE OF WORK

Provide a safer way for treating various cancers with PLGA-PEG-PLGA (PPP)-embedded iodine-125. To improve the safety of iodine treatment for colon cancer, iodine-125 solution was embedded into PLGA-PEG-PLGA (PPP) (synthesized by bulk co-polymerization of DL-polylactide glycolide and PEG). Xenograft-carrying nude mice were then treated with iodine-125-PPP. Proliferating cell nuclear antigen and Terminal Transferase dUTP Nick-End Labeling were used to measure proliferation and apoptosis in the tumors, respectively. Simultaneously, immunohistochemistry SP was used to detect the expression levels of p53. In addition, the microvessel density (MVD) of the tumors was recorded. PPP-embedded iodine-125 induced apoptosis by increasing the expression of p53, and by decreasing the levels of VEGF and MVD in the colon cancer tumors (P < 0.01). Significant inhibition of tumor growth is seen with iodine-125 from 0.4 to 0.8 mCi. PPP-embedded iodine-125 has a similar inhibitory efficiency to using the iodine-125 seeds for the treatment of colon tumors (P > 0.05). The findings therefore provide a potentially safer method for treating various tumors with radioactive iodine.

Potential role of probiotics on colorectal cancer prevention

Background

Colorectal cancer represents the most common malignancy of the gastrointestinal tract. Owing to differences in dietary habits and lifestyle, this neoplasm is more common in industrialized countries than in developing ones. Evidence from a wide range of sources supports the assumption that the link between diet and colorectal cancer may be due to an imbalance of the intestinal microflora.

Discussion

Probiotic bacteria are live microorganisms that, when administered in adequate amounts, confer a healthy benefit on the host, and they have been investigated for their protective anti-tumor effects. In vivo and molecular studies have displayed encouraging findings that support a role of probiotics in colorectal cancer prevention.

Summary

Several mechanisms could explain the preventive action of probiotics against colorectal cancer onset. They include: alteration of the intestinal microflora; inactivation of cancerogenic compounds; competition with putrefactive and pathogenic microbiota; improvement of the host’s immune response; anti-proliferative effects via regulation of apoptosis and cell differentiation; fermentation of undigested food; inhibition of tyrosine kinase signaling pathways.

The effects of probiotics on colon cancer development

While several effects beneficial to health have been attributed to the probiotic lactic acid bacteria, perhaps the most interesting and controversial remains that of anti-cancer activity. The vast majority of studies in this area deal with protective effects against colon cancer. There is no direct experimental evidence for cancer suppression in human subjects as a result of the consumption of probiotic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies. Reports in the literature, regarding the anti-cancer effects of lactic acid bacteria, fall into the following categories: in vitro studies, animal studies, epidemiological studies and human dietary intervention studies. Examples of these reports will be given in the present review. The mechanisms by which probiotic bacteria may inhibit colon cancer are still poorly understood. However, several potential mechanisms are being discussed in the literature and these will also be addressed in the present review.

Diadenosine 5',5''-(boranated)polyphosphonate analogues as selective nucleotide pyrophosphatase/phosphodiesterase inhibitors

Nucleotide pyrophosphatase/phosphodiesterases (NPPs) hydrolyze extracellular nucleotides and dinucleotides and thus control purinergic signaling. Enhanced NPP activity is implicated in health disorders such as osteoarthritis and cancer. We designed novel diadenosine polyphosphonate derivatives as potential NPP inhibitors. Analogues 1-4 bear a phosphonate and/or boranophosphate group and/or a 2'-H atom instead of a 2'-OH group. In comparison to ATP, analogues 1-4 were barely hydrolyzed by human NTPDase1, -2, -3, and -8 (<5% hydrolysis) and NPP1 and -3 (≤ 13%) and were not hydrolyzed by ecto-5'-nucleotidase, unlike AMP. These derivatives did not affect NTPDase activity, and analogues 1 and 2 did not inhibit ecto-5'-nucleotidase. All analogues blocked ∼80% of the NPP2-dependent hydrolysis of pnp-TMP, a specific NPP substrate, and inhibited the catabolism of pnp-TMP (K(i) and IC₅₀ both found to be between 10 and 60 μM), Ap₅A, and ATP by NPP1. The activity of NPP3 was inhibited to a lesser extent by the new analogues, with compounds 1 and 4 being the most effective in that respect. The analogues dramatically reduced the level of hydrolysis of pnp-TMP at the cell surface of both osteocarcinoma and colon cancer cells. Importantly, analogues 1-4 exhibited significantly reduced agonistic activity toward human P2Y₁,₁₁) receptors (except for analogue 1) and no activity with human P2Y₂ receptor. Our data provide strong evidence that analogue 2 is the first specific NPP inhibitor to be described.

Probiotic Lactobacillus acidophilus and L. casei mix sensitize colorectal tumoral cells to 5-fluorouracil-induced apoptosis

To assess the potential of Lactobacillus acidophilus and Lactobacillus casei strains to increase the apoptosis of a colorectal cancer cell line in the presence of 5-fluorouracil (5-FU), LS513 colorectal cancer cells were treated for 48 h with increasing concentrations of these lactic acid bacteria (LAB) in the presence of 100 mu g/ml of 5-FU. In the presence of 10(8) CFU/ml of live LAB, the apoptotic efficacy of the 5-FU increased by 40%, and the phenomenon was dose dependent. Moreover, irradiation-inactivated LAB caused the same level of induction, whereas microwave-inactivated LAB reduced the apoptotic capacity of the 5-FU. When cells were treated with a combination of live LAB and 5-FU, a faster activation of caspase-3 protein was observed, and the p21 protein seems to be downregulated. These results suggest that live L. acidophilus and L. casei are able to increase the apoptosis-induction capacity of 5-FU. The mechanisms of action are still not elucidated, and more research is needed to understand them. This is the first set of experiments demonstrating that some strains of LAB can enhance the apoptosis-induction capacity of the 5-FU. Based on these results, it is possible to speculate that LAB or probiotics could be used as an adjuvant treatment during anticancer chemotherapy.

Novel perspectives in probiotic treatment: the efficacy and unveiled mechanisms of the physiological functions

Probiotics are defined as "live microorganisms which confer a health benefit on the host" when administered in adequate amounts, and have potential effects for maintaining intestinal development, nutrition, and treating intestinal inflammations, functional disorders, and other extra-intestinal diseases. Although the benefits of probiotics for human health were first noted over 100 years ago, the analysis of probiotic functions began in earnest only 20 years ago. Probiotics, such as some strains of Lactobacillus, Bifidobacterium, Escherichia coli, and Bacillus subtilis, inhibit the growth of pathogenic bacteria, induce competitive effects for the adherent of pathogenic bacteria and their toxins to intestinal epithelia, induce cytoprotective heat shock proteins, enhance the intestinal barrier function, and modulate the host immune responses. The crosstalk between the host and the probiotics appears to be mediated by bacteria-derived effectors, which can be sensed with multiple systems, including the Toll-like receptors and cell membrane transporters. Future analyses will identify more probiotic-derived effectors, the recognition mechanisms of these effectors, and the subsequent changes of the intestinal epithelia and immune cells for each probiotic treatment. For clinical use, a procedure that objectively evaluates the ability of each probiotic effect will help establish a standard for choosing the most valuable strain and its proper dose for each individual patient.

Role of probiotics, prebiotics and synbiotics in chemoprevention for colorectal cancer

Colorectal cancer is the third most common form of cancer. Current treatments are all associated with a high risk of complications and a low success rate. Recently, synbiotics have been proposed as a new preventive and therapeutic option. There is no direct experimental evidence for cancer suppression in humans as a result of the consumption of pro-, pre- or synbiotics. However, there is a wealth of evidence emerging from laboratory studies. The mechanisms by which pro-, pre- and synbiotics may inhibit colon cancer are now beginning to be understood and will be addressed in the present review.

Roles of probiotics and prebiotics in colon cancer prevention: Postulated mechanisms and in-vivo evidence

Probiotics are live bacteria that could exert health beneficial effects upon consumption. In additional to their conventional use as gut modulators, probiotics are investigated for their role to prevent cancer. In-vivo and molecular studies have demonstrated encouraging outcomes, mainly attributed to its antimicrobial effects against carcinogen-producing microorganisms, antimutagenic properties, and alteration of the tumor differentiation processes. Prebiotics are indigestible food components that could promote the growth of beneficial bacteria including probiotics. Present studies have suggested that prebiotics also possess protective effect against colon carcinogenesis, mainly attributed to the production of short chain fatty acids upon its fermentation by gut microflora, and alteration of gene-expressions in tumor cells. Synbiotic (combination of probiotic and prebiotic) has been found to exert a synergistic effect in improving colon carcinogenesis compared to when both were used individually. This paper highlights the colon cancer preventive effects by probiotics, prebiotics and synbiotics. In addition, the controversial outcomes on the insignificant effect of these food adjuncts will be discussed.

Impact of lactic acid bacteria on oxidative DNA damage in human derived colon cells

It is assumed that reactive oxygen species (ROS) play a key role in inflammatory bowel diseases and colon cancer and a number of studies indicate that lactic acid bacteria (LAB) possess antioxidant properties and may prevent these diseases. In the present study, we developed a model which allowed us to investigate the prevention of oxidative DNA damage in human derived colon (HT29) cells by LAB. Furthermore, we investigated if these effects correlate with superoxide (O2(-)) resistance of the strains. The protective properties of 55 strains were monitored in single cell gel electrophoresis (SCGE) assays. After preincubation of the cells with LAB (60 min), oxidative damage was induced by exposure to plumbagin (5.0 microM, 120 min) which releases O2(-) or by hydrogen peroxide (50 microM, 10 min); O2(-) resistance was monitored in plate growth inhibition assays. 25 strains (45%) reduced plumbagin induced DNA migration while only few of them (20%) were protective towards hydrogen peroxide induced damage. The strongest effects (up to 60% reduction of O2(-) induced DNA migration) were observed with representatives of the species Streptococcus thermophilus. The prevention of DNA damage in the colon cells by the bacteria did not correlate with their O2(-) resistance. Additional experiments indicate that the reduction of oxidative damage is only seen with viable bacteria but not with heat inactivated cells and that it takes also place when the colon cells are separated from the LAB by permeable filter membranes indicating that the bacteria release ROS protective factors into the medium. Dose response experiments showed that the protection depends on the concentration of the bacteria; significant effects were observed with titers 3 x 10(6-7)cells/ml. Unexpectedly, we found that a substantial fraction of the strains (13%) induced DNA damage in untreated cells, some of them increased also the effects of the ROS generating chemicals. Preliminary experiments with tetramethylbenzidine (TMB) agar indicate that this phenomenon may be due to release of hydrogen peroxide by the bacteria. Overall, our study shows that the impact of LAB on DNA damage in human derived colon cells is ambivalent; while the majority of strains was protective against oxidative damage some of them induced per se pronounced DNA migration. Since the effects were seen with bacterial concentrations which may be reached in the intestinal tract after consumption of fermented milk products, it is likely that the effects we observed in the present study are relevant for humans.

Adherence and anticarcinogenic effects of Bacillus polyfermenticus SCD in the large intestine

AIMS

To investigate the probiotic properties of Bacillus polyfermenticus SCD such as their adherence to Caco-2 cells and anticarcinogenic effects on human colon cancer cells and rat colon cancer carcinogenesis.

METHODS AND RESULTS

The cell surface hydrophobicity and cell agglutination of B. polyfermenticus SCD was 64.04 +/- 1.25% and 297.3 +/- 8.7 mg ml(-1), respectively. This strain was strongly adherent to Caco-2 cells. Bacillus polyfermenticus SCD was also found to inhibit the growth of colon cancer cells in a dose-dependent manner as detected by the MTT assay. After 10 weeks of B. polyfermenticus SCD supplementation with 3 x 10(6) CFU day(-1) in F344 male rats, dimethylhydrazine-induced aberrant crypts and preneoplastic lesions decreased by 40% compared with the control rats.

CONCLUSIONS

Bacillus polyfermenticus SCD has strong adherent properties in the colon, and anticarcinogenic effects in vitro and in vivo.

SIGNIFICANCE AND IMPACT OF THE STUDY

These new findings on the characteristics of B. polyfermenticus SCD will be valuable in the evaluation of this commercial probiotic. Also, B. polyfermenticus SCD can be useful for the inhibition of colon cancer cells as an ingredient of medicinal foods or new drugs.

Probiotics and the incidence of colorectal cancer: when evidence is not evident

BACKGROUND

Colorectal cancer (CRC) is the second major cause of death from cancer in Europe and in the USA. Dietary factors and colonic microflora seem to play an important role in colorectal carcinogenesis, making the potential protective role of probiotics of overwhelming interest. METHODS AND AIM: This article analyzes existing data from basic science (animal and in vitro models) and human (epidemiological and interventional) studies to highlight areas for which more evidence is necessary. We interrogated Medline for studies analysing the risk of CRC and the use of probiotics and also screened the references of identified papers.

RESULTS

As far as regards animal models, we identified 29 studies aimed at evaluating the effect of probiotics administration on the incidence of CRC and/or of precursor lesions. All but one study using an animal model with spontaneous tumour growth in the background of colitis employed carcinogens, and most studies employed Lactobacilli or Bifidobacteria. All but 3 studies had positive results, and when prebiotics were evaluated too, the combination led to an important synergistic effect. The protective effect of probiotics seemed more important when they were administered before, and not after the carcinogen, and the putative mechanisms are not fully elucidated. Five papers evaluated the effect of probiotics on CRC cell lines in vitro, with results suggesting the ability of probiotics to modulate important cell functions and in a complex interplay. There are few human epidemiological studies specifically designed to analyze the effect of probiotics on CRC incidence, with important confounding factors, such as role of fibers, other dairy products and vitamin D often present. Overall, these studies fail to detect significant effects of fermented milks against CRC. Interventional studies suggest reduction of surrogate markers for CRC risk. However, one recent study showed no significant difference in the development of new CRC following administration of either fibers or probiotics in patients previously treated for colon neoplasm. A single randomised, double blind, placebo controlled pilot interventional trial aimed to evaluate the reduction in cancer risk biomarkers obtainable with the consumption of a symbiotic has been designed and started but a complete final report is not yet available.

CONCLUSIONS

In our search of the literature few and conflicting epidemiologic data regarding the impact of fermented dairy products consumption in humans have been gathered. There are no positive data from interventional studies so far. Therefore, even though an ample body of evidence supports the potential anticarcinogenic action of probiotics on the basis of the results obtained in both in vitro and in vivo models, further evidence is very much needed.

Review article: bifidobacteria as probiotic agents -- physiological effects and clinical benefits

Bifidobacteria, naturally present in the dominant colonic microbiota, represent up to 25% of the cultivable faecal bacteria in adults and 80% in infants. As probiotic agents, bifidobacteria have been studied for their efficacy in the prevention and treatment of a broad spectrum of animal and/or human gastrointestinal disorders, such as colonic transit disorders, intestinal infections, and colonic adenomas and cancer. The aim of this review is to focus on the gastrointestinal effects of bifidobacteria as probiotic agents in animal models and man. The traditional use of bifidobacteria in fermented dairy products and the GRAS ('Generally Recognised As Safe') status of certain strains attest to their safety. Some strains, especially Bifidobacterium animalis strain DN-173 010 which has long been used in fermented dairy products, show high gastrointestinal survival capacity and exhibit probiotic properties in the colon. Bifidobacteria are able to prevent or alleviate infectious diarrhoea through their effects on the immune system and resistance to colonization by pathogens. There is some experimental evidence that certain bifidobacteria may actually protect the host from carcinogenic activity of intestinal flora. Bifidobacteria may exert protective intestinal actions through various mechanisms, and represent promising advances in the fields of prophylaxis and therapy.

Fermented milks, probiotic cultures, and colon cancer

Colorectal cancer (CRC) is a major cause of death from cancer in the Western world. Approximately 70% of CRC is associated with environmental factors, probably mainly the diet. There is interest in the potential protective role of fermented milks containing probiotic cultures against CRC. This article analyzes the existing data from human, animal, and in vitro studies that explore whether consumption of milks fermented with probiotic cultures could play a role in colon cancer risk reduction. Cohort studies have failed to detect significant effects, but most case-control studies favor a protective role of fermented milks against colon cancer. Interventional studies have shown a shift of intermediate markers of CRC risk in human subjects from a high- to low-risk pattern after ingestion of fermented milks or probiotics. Animal studies consistently show a reduction in chemically induced colorectal tumor incidence and aberrant crypt formation accompanying probiotic administration. In vitro studies also provide evidence of protection, and permit a better understanding of active compounds involved, and of the mechanisms underlying their anticarcinogenic effects. Probiotics may beneficially modulate several major intestinal functions: detoxification, colonic fermentation, transit, and immune status, which may accompany the development of colon cancer. Although the evidence is not conclusive and much further research is required, the data reviewed constitute a promising body of evidence supporting the protective role of milks fermented with probiotic cultures in colon cancer risk reduction.

Inhibitory effect of yoghurt and soya yoghurt containing bifidobacteria on the proliferation of Ehrlich ascites tumour cells in vitro and in vivo in a mouse tumour model

The effect of yoghurt and soya yoghurt containing Bifidobacterium lactis Bb-12 or B. longum Bb-46 on Ehrlich ascites tumour cell proliferation was investigated in vitro and in vivo. Tumour cells were incubated with B. lactis Bb-12 or B. longum Bb-46 cultivated in de Mann Rogosa Sharpe (MRS) broth medium, or with their centrifuged supernatant fractions or sediments, for 2 h at 37 degrees C. Treatment resulted in the inhibition of tumour cell proliferation by 85.42 (SD 0.78) and 85.10 (SD 1.28) % by intact micro-organisms, 77.61 (SD 0.29) and 71.43 (SD 1.75) % by their supernatant fractions, but only 4.00 (SD 0.19) and 9.09 (SD 1.24) % by the two sedimented bacteria, respectively. The incubation of tumour cells with yoghurt and soya yoghurt containing Bb-12 for 2 h resulted in 83.01 (SD 0.11) and 88.23 (SD 0.06) % inhibition, respectively, while it was 83.82 (SD 0.24) and 86.36 (SD 0.06) %, respectively for the same products containing Bb-46. Corresponding values for plain yoghurt and soya milk (without bifidobacteria) were 32.81 (SD 0.14) and 5.55 (SD 0.12) %, respectively. The differences between yoghurt or soya yoghurt containing Bb-12 or Bb-46 and plain yoghurt, soya milk or control treatments were statistically significant (n 3; P<0.05). Female Swiss albino mice were injected intraperitoneally with the same tumour cells. The lifespan of mice fed diets supplemented with yoghurt or soya yoghurt containing Bb-12 or Bb-46 was prolonged by 16, 23, 34 and 39 %, respectively compared with that of the positive control group (n 6; P<0.05). The lifespan of groups fed plain yoghurt or soya milk was prolonged by 15 and 8 %, respectively. Prolongation of lifespan was positively correlated with faeces bifidobacterial count in the groups fed yoghurt or soya yoghurt containing bifidobacteria (r 0.917; P<0.05).

N/A

N/A

Probiotics and colon cancer

Although a myriad of health-promoting effects have been attributed to the probiotic lactic acid bacteria, perhaps the most interesting and controversial is that of anticancer activity, the vast majority of studies in this area dealing with protective effects against colon cancer. There is no direct experimental evidence for cancer suppression in humans as a result of the consumption of probiotic cultures in fermented or unfermented dairy products, but there is a wealth of indirect evidence, based largely on laboratory studies. Reports in the literature regarding the anticancer effects of lactic acid bacteria fall into the categories of in vitro studies, animal studies, epidemiological studies and human dietary intervention studies. Examples of these reports will be given in the current paper. The mechanisms by which probiotic bacteria may inhibit colon cancer are still poorly understood, but, several potential mechanisms are being discussed in the literature, and these will also be addressed in this review.

Lactic acid bacteria and cancer: mechanistic perspective

Colorectal cancer is one of the most important causes of cancer morbidity and mortality in Western countries. While a myriad of healthful effects have been attributed to the probiotic lactic acid bacteria (LAB), perhaps the most controversial remains that of anticancer activity. It should be pointed out that there is no direct experimental evidence for cancer suppression in man as a result of consumption of lactic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature. The precise mechanisms by which LAB may inhibit colon cancer are presently unknown. However, such mechanisms might include: alteration of the metabolic activities of intestinal microflora; alteration of physico-chemical conditions in the colon; binding and degrading potential carcinogens; quantitative and/or qualitative alterations in the intestinal microflora incriminated in producing putative carcinogen(s) and promoters (e.g. bile acid-metabolising bacteria); production of antitumourigenic or antimutagenic compounds; enhancing the host's immune response; and effects on physiology of the host. These potential mechanisms are addressed in the present paper.

Anti-proliferative effect of two lactic acid bacteria strains of human origin on the growth of a myeloma cell line

AIMS

Twenty lactic acid bacteria strains were isolated from human faeces and tested by MTT assay for stimulation or inhibition of the proliferation of Vero and myeloma cells.

METHODS AND RESULTS

None of the strains significantly affected the proliferation of Vero cells. However, two isolates (HN1 and HA8) showed a strong inhibition of myeloma cell proliferation (16.7 and 5.0%, respectively) by MTT assay.

CONCLUSION

Both strains have an anti-proliferative effect on a tumoral cell line.

SIGNIFICANCE AND IMPACT OF THE STUDY

The beneficial effect of LAB cancer therapy has been linked to their ability for immunomodulation.

The role of probiotic bacteria in cancer prevention

Colorectal cancer is one of the most important causes of cancer morbidity and mortality in western countries [1]. A myriad of healthful effects have been attributed to the probiotic lactic acid bacteria; perhaps the most controversial remains that of anticancer activity. There is no direct experimental evidence for cancer suppression in humans as a result of consumption of lactic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature and this will be summarised in the present paper.