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

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.

Kefir modulates gut microbiota and reduces DMH-associated colorectal cancer via regulation of intestinal inflammation in adulthood offsprings programmed by neonatal overfeeding

Obesity is associated with chronic inflammation, intestinal dysbiosis, and colorectal cancer risk. The anti-cancer effects of kefir are highlighted. Here, lactating Wistar rats were divided into: Normal litter (NL); Kefir normal litter (KNL); Small litter (SL); Kefir small litter (KSL). The NL and SL groups received 1 mL of water/day; KNL and KSL received kefir milk daily (10⁸ CFU/mL) during lactation. After weaning, the pups continued to receive the same treatments until 60 days. At 67 days old, colorectal carcinogenesis was induced through intraperitoneal injection of 1,2-dimethylhydrazine. At 240 days, visceral adipose tissue was higher in SL compared to NL, KNL, and KSL. Kefir intake was found to suppress the number of tumors in both KNL and KSL groups (-100% and -71.43%; p < 0.01, respectively). IL-1β, IL-6, TNF-α, and NO levels in the colon were higher in the NL and SL compared to the KNL and KSL. The gut microbiota in cecal samples of SL was enriched with Alloprevotella, Acinetobacter, and Bacteroides. In contrast, the cecal contents of KSL and KNL were higher Romboutsia. Thus, neonatal overfeeding leads to greater adiposity, inflammation and number of colon tumors in adulthood. Early-life nutrition based on kefir reverted these alterations.

Probiotic potential of Weissella paramesenteroides MYPS5.1 isolated from customary dairy products and its therapeutic application

Probiotics are viable microorganisms that confer general health benefits to the host when consumed in an adequate concentration. Probiotics may also possess strain-specific therapeutic properties and therefore finding novel strains with probiotic properties is becoming increasingly important. The present study has focused on the isolation of probiotic bacteria from dairy products which possessed potential therapeutic properties. Of the 79 strains isolated, eight were selected for further studies based on a number of traits including biofilm formation, deoxyribonuclease (DNase) activity, agglutination activity, auto-aggregation activity, antibiotic resistance, and antagonistic activity. Strain MYPS5.1 was selected from the eight isolates as the best potential probiotic candidate strain and was subsequently identified as Weissella paramesenteroides by 16S rDNA gene sequencing and sequence analysis. W. paramesenteroides strain MYPS5.1 was resistant to a number of antibiotics and the strain produced a high concentration of exopolysaccharide (EPS) (380.42 mg/L). The functional groups C-H, C = C, N = N, N-H, and C-O in the EPS were identified by using Fourier transform infrared (FTIR) spectroscopy. Computational studies showed that it interacted with cyclin-dependent kinase (CDK), a molecule which is thought to play a role in cancer pathogenesis (REF). Collectively, these results suggest that Weissella paramesenteroides MYPS5.1 is a potential probiotic strain with potential therapeutic properties.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03074-2.

Emerging prospects of macro- and microalgae as prebiotic

Macro- and microalgae-based foods are becoming popular due to their high nutritious value. The algal biomass is enriched with polysaccharides, protein, polyunsaturated fatty acids, carotenoids, vitamins and minerals. However, the most promising fraction is polysaccharides (PS) or their derivatives (as dietary fibers) which are not entirely fermented by colonic bacteria hence act as potential prebiotic. Primarily, algae become famous as prominent protein sources. Recently, these are widely adopted as functional food (e.g., desserts, dairy products, oil-derivatives, pastas etc.) or animal feed (for poultry, cattle, fish etc.). Besides prebiotic and balanced amino acids source, algae derived compounds implied as therapeutics due to comprising bioactive properties to elicit immunomodulatory, antioxidative, anticancerous, anticoagulant, hepato-protective, and antihypertensive responses. Despite the above potentials, broader research determinations are inevitable to explore these algal compounds until microalgae become a business reality for broader and specific applications in all health domains. However, scale up of algal bioprocess remains a major challenge until commercial affordability is accomplished which can be possible by discovering their hidden potentials and increasing their value and application prospects. This review provides an overview of the significance of algae consumption for several health benefits in humans and animals mainly as prebiotics, however their functional food and animal feed potential are briefly covered. Moreover, their potential to develop an algal-based food industry to meet the people's requirements not only as a sustainable food solution with several health benefits but also as therapeutics is inevitable.

Preclinical and clinical relevance of probiotics and synbiotics in colorectal carcinogenesis: a systematic review

CONTEXT

Recent evidence suggests that modulation of the gut microbiota may help prevent colorectal cancer.

OBJECTIVE

The aim of this systematic review was to investigate the role of probiotics and synbiotics in the prevention of colorectal cancer and to clarify potential mechanisms involved.

DATA SOURCES

The PubMed, ScienceDirect, and LILACS databases were searched for studies conducted in humans or animal models and published up to August 15, 2018.

STUDY SELECTION

Clinical trials and placebo-controlled experimental studies that evaluated the effects of probiotics and synbiotics in colorectal cancer and cancer associated with inflammatory bowel disease were included. Of 247 articles identified, 31 remained after exclusion criteria were applied. A search of reference lists identified 5 additional studies, for a total of 36 included studies.

DATA EXTRACTION

Two authors independently assessed risk of bias of included studies and extracted data. Data were pooled by type of study, ie, preclinical or clinical.

RESULTS

The results showed positive effects of probiotics and synbiotics in preventing colorectal cancer. The main mechanisms identified were alterations in the composition and metabolic activity of the intestinal microbiota; reduction of inflammation; induction of apoptosis and inhibition of tumor growth; modulation of immune responses and cell proliferation; enhanced function of the intestinal barrier; production of compounds with anticarcinogenic activity; and modulation of oxidative stress.

CONCLUSIONS

Probiotics or synbiotics may help prevent colorectal cancer, but additional studies in humans are required to better inform clinical practice.

Preclinical Evidence of Probiotics in Colorectal Carcinogenesis: A Systematic Review

BACKGROUND

Colorectal cancer, the second major cause of cancer deaths, imposes a major health burden worldwide. There is growing evidence that supports that the use of probiotics is effective against various diseases, especially in gastrointestinal diseases, including the colorectal cancer, but the differences between the strains, dose, and frequency used are not yet clear.

AIMS

To perform a systematic review to compile the results of studies carried out in animal models and investigated the effect of probiotics on colorectal carcinogenesis.

METHODS

Studies were selected in PubMed/MEDLINE and Scopus according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search filters were developed using three parameters: probiotics, colorectal cancer, and animal model.

RESULTS

From a structured search, we discovered 34 original articles and submitted them to a risk of bias analysis using SYRCLE's tool. The studies show a great diversity of models, most were conducted in rats (55.8%) and used 1,2 dimethylhydrazine as the drug to induce colorectal carcinogenesis (61.7%). The vast majority of trials investigated Lactobacillus (64%) and Bifidobacterium (29.4%) strains. Twenty-six (86.6%) studies found significant reduction in lesions or tumors in the animals that received probiotics. The main methodological limitation was the insufficient amount of information for the adequate reproducibility of the trials, which indicated a high risk of bias due to incomplete characterization of the experimental design.

CONCLUSIONS

The different probiotics' strains showed anti-carcinogenic effect, reduced the development of lesions and intestinal tumors, antioxidant and immunomodulatory activity, and reduced fecal bacterial enzymes.

Antioxidant and Anticancer Activities of Lactobacillus Hilgardii Strain AG12a

Background

It has been proven that probiotic Lactobacillus bacteria have inhibitory effects on human cancer cell lines. The aim of this study is to isolate and characterize the antioxidant probiotic Lactobacillus and determine the possible anticancer activities of the selected strain.

Methods

One of the Lactobacillus strain isolated from camel doogh sample showed the high antioxidant activity by using of different methods such as resistance to hydrogen peroxide, hydroxyl radical and superoxide anions. The antioxidant strain was characterized by sequencing of 16S rRNA V2-V3 regions and the 16S-23S intergenic spacer (ITS). The methanol extract of this strain supernatant was fractionated using thin layer chromatography (TLC) and antioxidant activity of fractions was detected by 0.1% of DPPH through TLC-DPPH bioautography. In vitro anticancer activity of each fraction was investigated by using MTT and flow cytometry methods.

Results

According to the phylogenetic results, the antioxidant Lactobacillus strain was closely related to Lactobacillus hilgardii strain E91 (Accession No. EF536365). After fractionation and anti-proliferation assessments of Lactobacillus hilgardii strain AG12a extracellular materials, one of the antioxidant fraction (F4) showed maximum DPPH radical scavenging activity (IC₅₀ of 535.27 μg/mL). MTT assay of the F4 fraction demonstrated cytotoxic activity against Caco-2 with the IC50 value of 299.05 μg/mL. The cell death activity of the fraction was confirmed by flow cytometry with 30.925.

Conclusions

In this study, the anticancer and apoptotic properties of Lactobacillus hilgardii against Caco-2 cell line was reported for the first time. The isolated bioactive fraction from the extracellular methanol extract needs to be further investigated in human studies of cancer therapy.

The Relationship between Prevention and Treatment of Colorectal Cancer and Cancerous Toxin Pathogenesis Theory Basing on Gut Microbiota

Gut microbiota is a diverse consortium of bacteria, fungi, protozoa, and viruses in the gut of all mammals. Gut microbiota remains in steady state under normal conditions. Changes in the internal and external environment may cause gut Microbiota to be out of tune. Malignant tumors are one of the major diseases currently endangering human health. CRC (colorectal cancer) has a significant upward trend in morbidity and mortality in many parts of the world. Technological advances have not yet brought about a breakthrough in the efficacy of CRC. The development of colon cancer is closely related to gut microbiota imbalance. According to more than 60 years of clinical practice, Professor Zhongying Zhou first proposed the pathogenesis theory of "cancerous toxin" in the 1990s and believed that cancerous toxin was a key pathogenesis of tumor development. Under the guidance of the theory of cancerous toxin, combined with clinical practice, Professor Zhou created an effective anticancer Chinese herbal compound, Jiedu Xiaoai Prescription. This paper summarizes recent hotspots related to gut microbiota and the occurrence, development, and prevention of colon cancer at home and abroad. The relationship between gut microbiota and cancerous toxin theory is proposed, and the feasibility of further studying the biological basis of cancerous toxin pathogenesis theory from the perspective of gut microbiota is pointed out.

Microbiome and Breast Cancer: New Role for an Ancient Population

There are many risk factors associated with breast cancer (BC) such as the familial history of BC, using hormone replacement therapy, obesity, personal habits, and other clinical factors; however, not all BC cases are attributed to these risk factors. Recent researches show a correlation between patient microbiome and BC suggested as a new risk factor. The present review article aimed at evaluating the role of the microbiome as a risk factor in the occurrence of BC, investigating the proposed mechanisms of interaction between the microbiome and human genes involved in BC, and assessing the impact of the altered composition of breast, gut, and milk microbiome in the physiological status of normal breast as well as cancerous or non-cancerous breast lesions. The study also evaluated the growing evidence that these altered populations may hinder chemotherapeutic treatment. The role of microbiome in the development and maintenance of inflammation, estrogen metabolism, and epigenetic alterations was properly investigated. Finally, clinical and therapeutic applications of the microbiome- e.g., probiotics, microbiome genome modulation, and engineered microbiome enzymes in the management of BC were reviewed.

Intestinal microbiota: a novel perspective in colorectal cancer biotherapeutics

It is believed that genetic factors, immune system dysfunction, chronic inflammation, and intestinal microbiota (IM) dysbiosis contribute to the pathogenesis of colorectal cancer (CRC). The beneficial role played by the direct regulation of IM in inflammatory bowel disease treatment is identified by the decreased growth of harmful bacteria and the increased production of anti-inflammatory factors. Interestingly, gut microbiota has been proven to inhibit tumor formation and progression in inflammation/carcinogen-induced CRC mouse models. Recently, evidence has indicated that IM is involved in the negative regulation of tumor immune response in tumor microenvironment, which then abolishes or accelerates anticancer immunotherapy in several tumor animals. In clinical trials, a benefit of IM-based CRC therapies in improving the intestinal immunity balance, epithelial barrier function, and quality of life has been reported. Meanwhile, specific microbiota signature can modulate host's sensitivity to chemo-/radiotherapy and the prognosis of CRC patients. In this review, we aim to 1) summarize the potential methods of IM-based therapeutics according to the recent results; 2) explore its roles and underlying mechanisms in combination with other therapies, especially in biotherapeutics; 3) discuss its safety, deficiency, and future perspectives.

Vitamin D/VDR, Probiotics, and Gastrointestinal Diseases

Vitamin D is an important factor in regulating inflammation, immune responses, and carcinoma inhibition via action of its receptor, vitamin D receptor (VDR). Recent studies have demonstrated the role of vitamin D/VDR in regulating host-bacterial interactions. Probiotics are beneficial bacteria with the power of supporting or favoring life on the host. In the current review, we will discuss the recent progress on the roles of vitamin D/VDR in gut microbiome and inflammation. We will summarize evidence of probiotics in modulating vitamin D/VDR and balancing gut microbiota in health and gastrointestinal diseases. Moreover, we will review the clinical application of probiotics in prevention and therapy of IBD or colon cancer. Despite of the gains, there remain several barriers to advocate broad use of probiotics in clinical therapy. We will also discuss the limits and future direction in scientific understanding of probiotics, vitamin D/VDR, and host responses.

Review of the mechanisms of probiotic actions in the prevention of colorectal cancer

The purpose of this review is to discuss the potential mechanisms of probiotics action in colorectal cancer prevention. In this regard, the composition of the intestinal microbiota is considered as an important risk factor in the development of colorectal cancer, and probiotics are able to positively modulate the composition of this microbiota. Studies have shown that the regular consumption of probiotics could prevent the development of colorectal cancer. In this respect, in vitro and experimental studies suggest some potential mechanisms responsible for this anticarcinogenic action. The mechanisms include modification of the intestinal microbiota composition, changes in metabolic activity of the microbiota, binding and degradation of carcinogenic compounds present in the intestinal lumen, production of compounds with anticarcinogenic activity, immunomodulation, improvement of the intestinal barrier, changes in host physiology, inhibition of cell proliferation, and induction of apoptosis in cancer cells. In contrast, very few reports demonstrate adverse effects of probiotic oral supplementation. In light of the present evidence, more specific studies are needed on probiotic bacteria, especially regarding the identification of the bacterial strains with greater anticarcinogenic potential; the verification of the viability of these strains after passing through the gastrointestinal tract; the investigation of potential adverse effects in immunocompromised individuals; and finally establishing the dosage and frequency of use.

Characterization of Lactobacillus plantarum Lb41, an isolate from kimchi and its application as a probiotic in cottage cheese

Lactobacillus plantarum Lb41 was determined probiotic properties and applied to cottage cheese. L. plantarum Lb41 showed high viability (>80%) in artificial gastric (pH 2.5, 0.3% pepsin for 3 h) and bile (0.3% oxgall for 24 h) acids, and adhered strongly to HT-29 cells (7.5% adhesion). It did not produce β-glucuronidase and was resistant to several antibiotics. L. plantarum Lb41 did not inhibit proliferation of normal MRC-5 cells, but showed antiproliferative effects on AGS, HT-29, and LoVo cells, based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. In addition, L. plantarum Lb41 reduced nitric oxide production by macrophages. Cottage cheese containing this strain did not show significant differences in physicochemical properties, but the number of lactic acid bacteria was maintained longer than that in control cheese. These results indicate that L. plantarum Lb41 could potentially be used as a probiotic in foods.

The Potential Role of Probiotics in Cancer Prevention and Treatment

The human gut microbiota has a significant effect on many aspects of human physiology such as metabolism, nutrient absorption, and immune function. Imbalance of the microbiota has been implicated in many disorders including inflammatory bowel disease, obesity, asthma, psychiatric illnesses, and cancers. As a kind of functional foods, probiotics have been shown to play a protective role against cancer development in animal models. Clinical application of probiotics indicated that some probiotic strains could diminish the incidence of postoperative inflammation in cancer patients. Chemotherapy or radiotherapy-related diarrhea was relieved in patients who were administered oral probiotics. The present review summarizes the up-to-date studies on probiotic effects and the underlying mechanisms related to cancer. At present, it is commonly accepted that most commercial probiotic products are generally safe and can improve the health of the host. By modulating intestinal microbiota and immune response, some strains of probiotics can be used as an adjuvant for cancer prevention or/and treatment.

Associations of Probiotics with Vitamin D and Leptin Receptors and their Effects on Colon Cancer

Colorectal cancer (CRC) is one of most common causes of cancer-related death worldwide. Recent studies have suggested that microbial and environmental factors including diet and lifestyle can impact on colon cancer development. Vitamin D deficiency and dysfunction of vitamin D receptor (VDR) also correlate with colon cancer. Moreover, leptin, a 16-kDa polypeptide, participates in the regulation of food intake and is associated with other environmental factors affecting colon cancer through the leptin receptor. Altered levels of serum leptin and patterns of expression of its receptor (LPR) may be observed in human colon tumours. Furthermore, the collected data from in vitro and in vivo studies have indicated that consuming probiotic non-pathogenic lactic acid bacteria have beneficial effects on colon cancer. Probiotics, inflammation and vitamin D/VDR have been correlated with leptin and its receptor and are also with colon cancer. Thus, in this paper, we review recent progress on the roles of probiotic, vitamin D/VDR and leptin/LPR in inflammation and colon cancer.

Probiotics against neoplastic transformation of gastric mucosa: Effects on cell proliferation and polyamine metabolism

Gastric cancer is still the second leading cause of cancer death worldwide, accounting for about 10% of newly diagnosed neoplasms. In the last decades, an emerging role has been attributed to the relations between the intestinal microbiota and the onset of both gastrointestinal and non-gastrointestinal neoplasms. 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. The internationally accepted definition of probiotics is live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The possible effects on the gastrointestinal tract following probiotic administration have been investigated in vitro and in animal models, as well as in healthy volunteers and in patients suffering from different human gastrointestinal diseases. Although several evidences are available on the use of probiotics against the carcinogen Helicobacter pylori, little is still known about the potential cross-interactions among probiotics, the composition and quality of intestinal flora and the neoplastic transformation of gastric mucosa. In this connection, a significant role in cell proliferation is played by polyamines (putrescine, spermidine, and spermine). These small amines are required in both pre-neoplastic and neoplastic tissue to sustain the cell growth and the evidences here provided suggest that probiotics may act as antineoplastic agents in the stomach by affecting also the polyamine content and functions. This review will summarize data on the most widely recognized effects of probiotics against neoplastic transformation of gastric mucosa and in particular on their ability in modulating cell proliferation, paying attention to the polyamine metabolism.

The interrelationships of the gut microbiome and inflammation in colorectal carcinogenesis

The cause of colorectal cancer (CRC) is multifactorial, with genetic, molecular, inflammatory, and environmental risk factors. Recently, the gut microbiota has been recognized as a new environmental contributor to CRC in both animal models and human studies. An additional interplay of the gut microbiome with inflammation is also evident in studies that have shown that inflammation alone or the presence of bacteria/bacterial metabolites alone is not enough to promote tumorigenesis. Rather, complex interrelationships with the gut microbiome, inflammation, genetics, and other environmental factors are evident in progression of colorectal tumors.

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.

Physiological Properties and Salmonella Growth Inhibition of Probiotic Bacillus Strains Isolated from Environmental and Poultry Sources

The objective of the present study was to describe the physiological properties of seven potential probiotic strains of Bacillus spp. Isolates were characterized morphologically, biochemically, and by 16S rRNA sequence analyses for identification. Tolerance to acidic pH, high osmotic concentrations of NaCl, and bile salts were tested. Isolates were also evaluated for their ability to metabolize different carbohydrates sources. The antimicrobial sensitivity profiles were determined. Inhibition of gastrointestinal Salmonella colonization in an avian model was also evaluated. Five strains of Bacillus were tolerant to acidic conditions (pH 2.0) and all strains were tolerant to a high osmotic pressure (NaCl at 6.5%). Moreover, all strains were able to tolerate concentration of 0.037% bile salts after 24 h of incubation. Three strains were able to significantly reduce Salmonella Typhimurium levels in the crop and in the ceca of broiler-type chickens. Among the 12 antibiotics tested for antibiotic resistance, all strains were resistant to bacitracin and susceptible to gentamycin, neomycin, ormethoprim, triple sulfa, and spectinomycin. Bacterial spore formers have been shown to prevent gastrointestinal diseases in animals and humans. The results obtained in this study show important characteristics to be evaluated when selecting Bacillus spp. candidates to be used as probiotics.

Identifying molecular targets of lifestyle modifications in colon cancer prevention

One in four deaths in the United States is cancer-related, and colorectal cancer (CRC) is the second leading cause of cancer-associated deaths. Screening strategies are utilized but have not reduced disease incidence or mortality. In this regard, there is an interest in cancer preventive strategies focusing on lifestyle intervention, where specific etiologic factors involved in cancer initiation, promotion, and progression could be targeted. For example, exposure to dietary carcinogens, such as nitrosamines and polycyclic aromatic hydrocarbons influences colon carcinogenesis. Furthermore, dietary deficiencies could alter sensitivity to genetic damage and influence carcinogen metabolism contributing to CRC. High alcohol consumption increases the risk of mutations including the fact that acetaldehyde, an ethanol metabolite, is classified as a group 1 carcinogen. Tobacco smoke exposure is also a risk factor for cancer development; approximately 20% of CRCs are associated with smoking. Additionally, obese patients have a higher risk of cancer development, which is further supported by the fact that physical activity decreases CRC risk by 55%. Similarly, chronic inflammatory conditions also increase the risk of CRC development. Moreover, the circadian clock alters digestion and regulates other biochemical, physiological, and behavioral processes that could influence CRC. Taken together, colon carcinogenesis involves a number of etiological factors, and therefore, to create effective preventive strategies, molecular targets need to be identified and beleaguered prior to disease progression. With this in mind, the following is a comprehensive review identifying downstream target proteins of the above lifestyle risk factors, which are modulated during colon carcinogenesis and could be targeted for CRC prevention by novel agents including phytochemicals.

The role of gut microbiota in the pathogenesis of colorectal cancer

The human gastrointestinal tract harbors a complex and abundant microbial community that can reach levels as high as 10(13)-10(14) microorganisms in the colon. These microorganisms are essential to a host's well-being in terms of nutrition and mucosa immunity. However, numerous studies have also implicated members of the colonic microbiota in the development of colorectal cancer (CRC). While CRC involves a genetic component where damaged DNA and genetic instability initiates a malignant transformation, environmental factors can also contribute to the onset of CRC. Furthermore, considering the constant exposure of the colonic mucosa to the microbiome and/or its metabolites, the mucosa has long been proposed to contribute to colon tumorigenesis. However, the mechanistic details of these associations remain unknown. Fortunately, due to technical and conceptual advances, progress in characterizing the taxonomic composition, metabolic capacity, and immunomodulatory activity of human gut microbiota have been made, thereby elucidating its role in human health and disease. Furthermore, the use of experimental animal models and clinical/epidemiological studies of environmental etiological factors has identified a correlation between gut microbiota composition and gastrointestinal cancers. Bacteria continuously stimulate activated immunity in the gut mucosa and also contribute to the metabolism of bile and food components. However, the highest levels of carcinogen production are also associated with gut anaerobic bacteria and can be lowered with live lactobacilli supplements. In this review, evidence regarding the relationship between microbiota and the development of CRC will be discussed, as well as the role for microbial manipulation in affecting disease development.

Potential probiotic lactic acid bacteria of human origin induce antiproliferation of colon cancer cells via synergic actions in adhesion to cancer cells and short-chain fatty acid bioproduction

The activities and modes of probiotic action of lactic acid bacteria isolated from infant feces were investigated for alternative application in the prevention and biotherapy of colon cancer. From a total of 81 isolates of Gram-positive rod and cocci bacteria obtained from healthy infants, only 15 isolates had the probiotic criteria which included growth inhibition against eight food-borne pathogens, no blood hemolysis, and tolerance to gastrointestinal tract properties such as pH 2.5 and 0.3 % bile salt. Four probiotic bacteria showed antiproliferation of colon cancer cells with the use of MTT and Trypan blue exclusion assay at the rates of 17-35 %. Through comparison of probiotic 16S rRNA sequences, they were identified as Pediococcus pentosaceus FP3, Lactobacillus salivarius FP25, L. salivarius FP35, and Enterococcus faecium FP51. Finding the mechanism of proliferative inhibition of colon cancer cells in this study indicated synergic induction by probiotic bacteria directly adhered to these cancer cells and triggered the bioproduction of short-chain fatty acids, mainly butyric and propionic acids. This study suggested that the use of these probiotics may be suitable as an alternative bioprophylactic and biotherapeutic strategy for colon cancer.

[Gut microbial influence and probiotics on colorectal cancer]

The human intestinal microbiota is a community of 10(13)-10(14) microorganisms that harbor in the intestine and normally participate in a symbiotic relationship with human. Technical and conceptual advances have enabled rapid progress in characterizing the taxonomic composition, metabolic capacity and immunomodulatory activity of the human intestinal microbiota. Their collective genome, defined as microbiome, is estimated to contain ≥150 times as many genes as 2.85 billion base pair human genome. The intestinal microbiota and its microbiome form a diverse and complex ecological community that profoundly impact intestinal homeostasis and disease states. It is becoming increasingly evident that the large and complex bacterial population of the large intestine plays an important role in colorectal carcinogenesis. Numerous studies show that gut immunity and inflammation have impact on the development of colorectal cancer. Additionally, bacteria have been linked to colorectal cancer by the production of toxic and genotoxic bacterial metabolite. In this review, we discuss the multifactorial role of intestinal microbiota in colorectal cancer and role for probiotics in the prevention of colorectal cancer.

Spore-forming bacteria and their utilisation as probiotics

In this review article, the beneficial application of bacterial spore formers as probiotics in the food industry is discussed based on the knowledge gleaned from current publications. The summary of new scientific results provides evidence of the advantages of the utilisation of Bacillus or Clostridium strains in the food industry. Both bacteria are able to produce a very stable duration form: the endospore. Compared to the widely used lactic acid bacteria, bacterial spores offer the advantage of a higher survival rate during the acidic stomach passage and better stability during the processing and storage of the food product. In many food products, germination of the spores does not occur. Hence the product quality of the food is not affected because of their inactive metabolism. Besides the possible utilisation and functional properties, an overview of the fast-developing knowledge about the mechanisms of the beneficial health effects of spore-forming bacteria is provided.

Gut microbiota and probiotics in colon tumorigenesis

The human gastrointestinal tract harbors a complex and abundant microbial community reaching as high as 10(13)-10(14) microorganisms in the colon. This endogenous microbiota forms a symbiotic relationship with their eukaryotic host and this close partnership helps maintain homeostasis by performing essential and non-redundant tasks (e.g. nutrition/energy and, immune system balance, pathogen exclusion). Although this relationship is essential and beneficial to the host, various events (e.g. infection, diet, stress, inflammation) may impact microbial composition, leading to the formation of a dysbiotic microbiota, further impacting on health and disease states. For example, Crohn's disease and ulcerative colitis, collectively termed inflammatory bowel diseases (IBD), have been associated with the establishment of a dysbiotic microbiota. In addition, extra-intestinal disorders such as obesity and metabolic syndrome are also associated with the development of a dysbiotic microbiota. Consequently, there is an increasing interest in harnessing the power of the microbiome and modulating its composition as a means to alleviate intestinal pathologies/disorders and maintain health status. In this review, we will discuss the emerging relationship between the microbiota and development of colorectal cancer as well as present evidence that microbial manipulation (probiotic, prebiotic) impacts disease development.

The anticancer effect of probiotic Bacillus polyfermenticus on human colon cancer cells is mediated through ErbB2 and ErbB3 inhibition

A wealth of data implicates that ErbB receptors have essential roles in tumor development. Probiotic bacteria are known to exert an anticancer activity in animal studies. Bacillus polyfermenticus (B.P.), a probiotic bacterium, has been clinically used for a variety of gastrointestinal disorders in East Asia. Here, we investigated the effect of B.P. on the growth of tumors and its putative mechanism of actions. Conditioned medium of B.P. cultures (B.P. CM) inhibited the growth of human colon cancer cells including HT-29, DLD-1 and Caco-2 cells. Moreover, B.P. CM suppressed colony formation of HT-29 cells cultured on soft agar and reduced carcinogen-induced colony formation of normal colonocytes. Furthermore, data from the mouse xenograft model of human colon cancer cells showed reduced tumor size in B.P. CM-injected mice when compared to E. coli conditioned medium-injected mice. Exposure of B.P. CM to HT-29 cells for 24 hr, 48 hr and 2 weeks reduced ErbB2 and ErbB3 protein expression as well as mRNA levels. Moreover, cyclin D1 expression that is required for ErbB-dependent cell transformation was decreased by B.P. CM. Furthermore, transcription factor E2F-1 that regulates cyclin D1 expression was also decreased by B.P. CM. These results show that B.P. inhibits tumor growth and its anticancer activity occurs, at least in part, through suppressing ErbB2 and ErbB3. Taken together, our study suggests that this probiotic may be clinically used as a prophylactic treatment to prevent colon cancer development.

The angiogenic effect of probiotic Bacillus polyfermenticus on human intestinal microvascular endothelial cells is mediated by IL-8

Angiogenesis is required for wound healing and repair, but dysregulated angiogenesis is involved in gastrointestinal inflammation. Bacillus polyfermenticus (B.P.) is a probiotic bacterium clinically used for a variety of intestinal disorders in East Asia. Here we investigated the effect of B.P. on angiogenesis of human intestinal microvascular endothelial cells (HIMECs) and wound healing in intestinal mucosa. Exposure of HIMECs to the conditioned medium of B.P. cultures (B.P. CM) increased cell migration, permeability, and tube formation. Production of the proangiogenic cytokine IL-8 was increased by B.P. CM, and neutralizing antibodies against IL-8 or IL-8 receptor CXCR2 reduced tube formation as well as actin stress fiber formation. B.P. CM also increased NF-kappaB activation, and inhibitors of NF-kappaB suppressed B.P. CM-induced tube formation and IL-8 production. Furthermore, B.P. facilitated recovery of mice from colitis as shown by increased body weight and reduced rectal bleeding and histological severity. B.P. also increased angiogenesis and mouse IL-8 production in the mucosal layer. Collectively, these results show that B.P. increases angiogenesis of HIMECs in a NF-kappaB/IL-8/CXCR2-dependent manner. Moreover, B.P. promotes angiogenesis in the mucosa during recovery of mice from colitis, suggesting that this probiotic may be clinically used to facilitate intestinal wound healing.

Probiotics for the prevention of respiratory tract infections: a systematic review

We evaluated the clinical evidence regarding probiotic use for the prevention of respiratory tract infections (RTIs). Randomised controlled trials (RCTs) studying the effects of probiotics for the prevention of upper or lower RTIs were systematically identified. Fourteen RCTs (twelve involving healthy subjects and two involving patients with RTIs) were included. Various Lactobacillus strains were used in seven RCTs, combinations of Lactobacillus and Bifidobacterium strains were used in five RCTs, and a Bifidobacterium strain and a non-pathogenic Enterococcus faecalis strain were used in one RCT, respectively. In ten RCTs no difference was found regarding the incidence of RTIs in the probiotic arm compared with the control arm, whereas the remaining four RCTs favoured the use of probiotics. Reduction in the severity of symptoms related to RTIs was noted in five of six RCTs that provided relevant data. In three of nine RCTs that provided relevant data, the clinical course of RTIs was shorter in the probiotic arm, whereas no difference was found in the remaining six RCTs. In conclusion, probiotics may have a beneficial effect on the severity and duration of symptoms of RTIs but do not appear to reduce the incidence of RTIs.