Probiotics Lactobacillus rhamnosus GG, Lactobacillus acidophilus suppresses DMH-induced procarcinogenic fecal enzymes and preneoplastic aberrant crypt foci in early colon carcinogenesis in Sprague Dawley rats

Analyzing of colorectal cancerrelated genes and microRNAs expression profiles in response to probiotics Lactobacillus acidophilus and Saccharomyces cerevisiae in colon cancer cell lines

BACKGROUND

Colorectal cancer is the world's third most frequent cancer and the fourth cause of mortality. Probiotics play an important function in preventing metastasis as well as the growth and proliferation of malignant cancer cells.

METHODS AND RESULTS

The study investigated the anticancer effect of Lactobacillus acidophilus supernatant and Saccharomyces cerevisiae yeast on colorectal cell lines, including HT29 and SW480 as a colorectal cancer model. The extract from the Lactobacillus acidophilus and Saccharomyces cerevisiae standard probiotics were prepared, and probiotics characterization was confirmed by morphological and Biochemical tests. The viability of HT29 and SW480 colon cancer cell lines on effecting probiotic supernatant was evaluated by measuring the MTT colorimetric method. Comparison of the expression profile of several genes involved in apoptosis, cell cycle, and metastatic pathway in HT29 and SW480 cell lines with the treatment of probiotics extract showed an upregulation in the BAX, CASP3, and CASP9 and down regulation BCl-2, MMP2, and MMP9 genes. Also, a comparison of microRNA expression profiles indicated an increase of miR 34, 135, 25, 16, 195, 27, 98, let7 and a decrease of miR 9, 106b, 17, 21, 155, 221.

CONCLUSIONS AND DISCUSSION

The findings of this study indicate that probiotics can effectively suppress the proliferation of colorectal cancer cells and even reverse their development. Additionally, the study of cellular genes and miRNA profiles associated with colorectal cancer have demonstrated that our probiotics play a crucial role in CRC prevention by increasing the expression of tumor suppressor microRNAs and their target genes while decreasing oncogenes.

Probiotics intervention in colorectal cancer: From traditional approaches to novel strategies

ABSTRACT

The intestine harbors a large population of microorganisms that interact with epithelial cells to maintain host healthy physiological status. These intestinal microbiota engage in the fermentation of non-digestible nutrients and produce beneficial metabolites to regulate host homeostasis, metabolism, and immune response. The disruption of microbiota, known as dysbiosis, has been implicated in many intestinal diseases, including colorectal cancer (CRC). As the third most common cancer and the second leading cause of cancer-related death worldwide, CRC poses a significant health burden. There is an urgent need for novel interventions to reduce CRC incidence and improve clinical outcomes. Modulating the intestinal microbiota has emerged as a promising approach for CRC prevention and treatment. Current research efforts in CRC probiotics primarily focus on reducing the incidence of CRC, alleviating treatment-related side effects, and potentiating the efficacy of anticancer therapy, which is the key to successful translation to clinical practice. This paper aims to review the traditional probiotics and new interventions, such as next-generation probiotics and postbiotics, in the context of CRC. The underlying mechanisms of probiotic anti-cancer effects are also discussed, including the restoration of microbial composition, reinforcement of gut barrier integrity, induction of cancer cell apoptosis, inactivation of carcinogens, and modulation of host immune response. This paper further evaluates the novel strategy of probiotics as an adjuvant therapy in boosting the efficacy of chemotherapy and immunotherapy. Despite all the promising findings presented in studies, the evaluation of potential risks, optimization of delivery methods, and consideration of intra-patient variability of gut microbial baseline must be thoroughly interpreted before bench-to-bedside translation.

Lactobacillus rhamnosus probiotic treatment modulates gut and liver inflammatory pathways in a hepatocellular carcinoma murine model. A preliminary study

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is a growing global concern with an increasing incidence rate. The intestinal microbiota has been identified as a potential culprit in modulating the effects of antitumoral drugs. We aimed to assess the impact of adding Lactobacillus rhamnosus probiotic to regorafenib in mice with HCC.

METHODS

Cirrhosis and HCCs were induced in 56 male Swiss mice via diethylnitrosamine injection and carbon tetrachloride administration. Mice were divided into four groups: treated with vehicle (VC), regorafenib (Rego), L. rhamnosus probiotic, and a combination of regorafenib and probiotic (Rego-Pro). After 3 weeks of treatment, liver and intestinal fragments were collected for analysis.

RESULTS

Regorafenib elevated gut permeability, an effect mitigated by probiotic intervention, which exhibited a notable correlation with reduced inflammation (p < 0.01). iNOS levels were also reduced by adding the probiotic with respect to the mice treated with regorafenib only (p < 0.001). Notably, regorafenib substantially increased IL-6, TNF-a and TLR4 in intestinal fragments (p < 0.01). The administration of the probiotic effectively restored IL-6 to its initial levels (p < 0.001).

CONCLUSION

Reducing systemic and intestinal inflammation by administering L. rhamnosus probiotic may alleviate tumoral resistance and systemic adverse effects.

Purine nucleosidase (PNase) activity, probiotics potential, and food applicability of a newly-isolated Levilactobacillus brevis LAB42

Hyperuricemia, a condition characterized by elevated levels of uric acid in the blood, is known as a risk factor for gout disease. In this study, we isolated a total of 72 MRS-grown colonies and evaluated their purine nucleosidase (PNase) activity. Among the isolated bacteria, Levilactobacillus (L.) brevis LAB42 displayed the highest PNase activity. Our findings also indicate that PNase activity can vary among lactic acid bacterial strains and during different growth phases. Based on the kinetics study, LAB42 consistently exhibits the highest PNase activity. Due to its ability to attach to Caco-2 cells and its resistance to acidic environments and bile exposure, L. brevis LAB42 was chosen for further studies and showed that with the right combination of additives, it has the potential to be an appropriate starter for milk fermentation.

Association between Probiotics and Modulation of Gut Microbial Community Composition in Colorectal Cancer Animal Models: A Systematic Review (2010-2021)

Background

Colorectal cancer (CRC) is one of the most prevalent gastrointestinal malignancies and is considered the third major cause of mortality globally. Probiotics have been shown to protect against the CRC cascade in numerous studies.

Aims

The goal of this systematic review was to gather the preclinical studies that examined the impact of probiotics on the alteration of gut microbiota profiles (bacterial communities) and their link to colorectal carcinogenesis as well as the potential processes involved.

Methods

The search was performed using Scopus, Web of Science, and PubMed databases. Five parameters were used to develop search filters: "probiotics," "prebiotics," "synbiotics," "colorectal cancer," and "animal model."

Results

Of the 399 full texts that were screened, 33 original articles met the inclusion criteria. According to the current findings, probiotics/synbiotics could significantly attenuate aberrant crypt foci (ACF) formation, restore beneficial bacteria in the microbiota population, increase short-chain fatty acids (SCFAs), and change inflammatory marker expression.

Conclusions

The present systematic review results indicate that probiotics could modulate the gut microbial composition and immune regulation to combat/inhibit CRC in preclinical models. However, where the evidence is more limited, it is critical to transfer preclinical research into clinical data.

Why Does Obesity as an Inflammatory Condition Predispose to Colorectal Cancer?

Obesity is a complex and multifactorial problem of global importance. Additionally, obesity causes chronic inflammation, upregulates cell growth, disturbs the immune system, and causes genomic instability, increasing the risk of carcinogenesis. Colorectal cancer is one of the most common cancers, and it has become a global problem. In 2018, there were around 1.8 million new cases and around 881,000 deaths worldwide. Another risk factor of colorectal cancer associated with obesity is poor diet. A Western diet, including a high intake of red and processed meat and a low consumption of whole grains, fruits, vegetables, and fiber, may increase the risk of both colorectal cancer and obesity. Moreover, the Western diet is associated with a proinflammatory profile diet, which may also affect chronic low-grade inflammation. In fact, people with obesity often present gut dysbiosis, increased inflammation, and risk of colorectal cancer. In this article, the association between obesity and colorectal cancer is discussed, including the most important mechanisms, such as low-grade chronic inflammation, gut dysbiosis, and poor diet.

Implication of Obesity and Gut Microbiome Dysbiosis in the Etiology of Colorectal Cancer

The complexity and variety of gut microbiomes within and among individuals have been extensively studied in recent years in connection to human health and diseases. Our growing understanding of the bidirectional communication between metabolic diseases and the gut microbiome has also highlighted the significance of gut microbiome dysbiosis in the genesis and development of obesity-related cancers. Therefore, it is crucial to comprehend the possible role of the gut microbiota in the crosstalk between obesity and colorectal cancer (CRC). Through the induction of gut microbial dysbiosis, gut epithelial barrier impairment, metabolomic dysregulation, chronic inflammation, or dysregulation in energy harvesting, obesity may promote the development of colorectal tumors. It is well known that strategies for cancer prevention and treatment are most effective when combined with a healthy diet, physical activity, and active lifestyle choices. Recent studies also suggest that an improved understanding of the complex linkages between the gut microbiome and various cancers as well as metabolic diseases can potentially improve cancer treatments and overall outcomes. In this context, we herein review and summarize the clinical and experimental evidence supporting the functional role of the gut microbiome in the pathogenesis and progression of CRC concerning obesity and its metabolic correlates, which may pave the way for the development of novel prognostic tools for CRC prevention. Therapeutic approaches for restoring the microbiome homeostasis in conjunction with cancer treatments are also discussed herein.

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.

Exploiting lactic acid bacteria for colorectal cancer: a recent update

Colorectal cancer (CRC) is the third most common cancer in the world. Currently, chemotherapy and radiotherapy used to treat CRC exhibit many side effects, hence, it is an urgent need to design effective therapies to prevent and treat CRC. Lactic acid bacteria (LAB) can regulate gut microbiota, intestinal immunity, and intestinal mechanical barrier, which is becoming a hot product for the prevention and treatment of CRC, whereas comprehensive reviews of their anti-CRC mechanisms are limited. This review systematically reveals the latest incidence, mortality, risk factors, and molecular mechanisms of CRC, then summarizes the roles of probiotics in alleviating CRC in animal and clinical studies and critically reviews the possible mechanisms by which these interventions exert their activities. It then shows the limitations in mechanisms and clinical studies, and the suggestions for future research are also put forward, which will play an important role in guiding and promoting the basic and clinical research of remising CRC by LAB and the development of LAB products.

IP6 reduces colorectal cancer metastasis by mediating the interaction of gut microbiota with host genes

Inositol hexaphosphate (IP6) is a phytochemical widely found in grains and legumes that plays an anti-cancer role. However, the mechanism underlying the inhibition of colorectal cancer metastasis by IP6 through host genes, gut microbiota, and their interactions remain elusive. In this study, 16S rRNA sequencing was used to study the effect of IP6 on gut microbiota in an orthotopic transplantation model of colorectal cancer mice. The transcriptome was used to study the changes of host genes in metastasis and the relationship with gut microbiota. The results showed that the gut microbiota composition of model mice was significantly different from that of normal mice. The beta diversity partly tended to return to the normal level after IP6 intervention. Especially, Lactobacillus helveticus and Lactococcus lactis were recovered after IP6-treated. Enrichment analysis showed that the enrichment score of the Cytokine-Cytokine receptor interaction signal pathway decreased after IP6 treatment compared to the model group. Further analysis of differentially expressed genes (DEGs) in this pathway showed that IP6 reduced the expression of the Tnfrsf1b gene related to the area of liver metastasis, and the Tnfrsf1b gene was negatively correlated with the relative abundance of Lactobacillus helveticus. Our results presented that host gene, microbiome and their interaction may serve as promising targets for the mechanism of IP6 intervention in colorectal cancer metastasis.

Tumor Microenvironment Shapes Colorectal Cancer Progression, Metastasis, and Treatment Responses

Colorectal cancer (CRC) is one of the most devastating diseases that accounts for numerous deaths worldwide. Tumor cell-autonomous pathways, such as the oncogenic signaling activation, significantly contribute to CRC progression and metastasis. Recent accumulating evidence suggests that the CRC microenvironment also profoundly promotes or represses this process. As the roles of the tumor microenvironment (TME) in CRC progression and metastasis is gradually uncovered, the importance of these non-cell-autonomous signaling pathways is appreciated. However, we are still at the beginning of this TME function exploring process. In this review, we summarize the current understanding of the TME in CRC progression and metastasis by focusing on the gut microbiota and host cellular and non-cellular components. We also briefly discuss TME-remodeling therapies in CRC.

An Update on the Effects of Probiotics on Gastrointestinal Cancers

Because of their increasing prevalence, gastrointestinal (GI) cancers are regarded as an important global health challenge. Microorganisms residing in the human GI tract, termed gut microbiota, encompass a large number of living organisms. The role of the gut in the regulation of the gut-mediated immune responses, metabolism, absorption of micro- and macro-nutrients and essential vitamins, and short-chain fatty acid production, and resistance to pathogens has been extensively investigated. In the past few decades, it has been shown that microbiota imbalance is associated with the susceptibility to various chronic disorders, such as obesity, irritable bowel syndrome, inflammatory bowel disease, asthma, rheumatoid arthritis, psychiatric disorders, and various types of cancer. Emerging evidence has shown that oral administration of various strains of probiotics can protect against cancer development. Furthermore, clinical investigations suggest that probiotic administration in cancer patients decreases the incidence of postoperative inflammation. The present review addresses the efficacy and underlying mechanisms of action of probiotics against GI cancers. The safety of the most commercial probiotic strains has been confirmed, and therefore these strains can be used as adjuvant or neo-adjuvant treatments for cancer prevention and improving the efficacy of therapeutic strategies. Nevertheless, well-designed clinical studies are still needed for a better understanding of the properties and mechanisms of action of probiotic strains in mitigating GI cancer development.

Dietary Patterns and Associated Microbiome Changes that Promote Oncogenesis

The recent increases in cancer incidences have been linked to lifestyle changes that result in obesity and metabolic syndrome. It is now evident that these trends are associated with the profound changes that occur in the intestinal microbiome, producing altered microbial population signatures that interact, directly or indirectly, with potentially pro-carcinogenic molecular pathways of transcription, proliferation, and inflammation. The effects of the entire gut microbial population on overall health are complex, but individual bacteria are known to play important and definable roles. Recent detailed examinations of a large number of subjects show a tight correlation between habitual diets, fecal microbiome signatures, and markers of metabolic health. Diets that score higher in healthfulness or diversity such as plant-based diets, have altered ratios of specific bacteria, including an increase in short-chain fatty acid producers, which in turn have been linked to improved metabolic markers and lowered cancer risk. Contrarily, numerous studies have implicated less healthy, lower-scoring diets such as the Western diet with reduced intestinal epithelial defenses and promotion of specific bacteria that affect carcinogenic pathways. In this review, we will describe how different dietary patterns affect microbial populations in the gut and illustrate the subsequent impact of bacterial products and metabolites on molecular pathways of cancer development, both locally in the gut and systemically in distant organs.

Probiotic consumption influences universal adaptive mutations in indigenous human and mouse gut microbiota

The adaptive evolution in indigenous intestinal microbes derived from probiotics is critical to safety and efficacy evaluation of probiotics, yet it is still largely underexplored. Here, through 11 publicly accessible datasets, we demonstrated that probiotic consumption can lead to widespread single-nucleotide variants (SNVs) in the native microbiota. Interestingly, the same probiotic strains introduced far more SNVs in mouse gut than humans. Furthermore, the pattern of probiotics-induced SNVs was highly probiotic-strain specific, and 17 common SNVs in Faecalibacterium prausnitzii genome were identified cross studies, which might lead to changes in bacterial protein structure. Further, nearly 50% of F. prausnitzii SNVs can be inherited for six months in an independent human cohort, whereas the other half only transiently occurred. Collectively, our study substantially extended our understanding of co-evolution of the probiotics and the indigenous gut microbiota, highlighting the importance of assessment of probiotics efficacy and safety in an integrated manner.

Chenchen Ma, Chengcheng Zhang, and Denghui Chen et al. examine how probiotic consumption impacts gut microbiota composition in human and mice through a global, cross-cohort metagenomic analysis. Their results suggest that probiotic consumption may result in widespread variation among the native microbiota in both the human and mouse gut.

Polyphenol-Enriched Blueberry Preparation Controls Breast Cancer Stem Cells by Targeting FOXO1 and miR-145

Scientific evidence supports the early deregulation of epigenetic profiles during breast carcinogenesis. Research shows that cellular transformation, carcinogenesis, and stemness maintenance are regulated by epigenetic-specific changes that involve microRNAs (miRNAs). Dietary bioactive compounds such as blueberry polyphenols may modulate susceptibility to breast cancer by the modulation of CSC survival and self-renewal pathways through the epigenetic mechanism, including the regulation of miRNA expression. Therefore, the current study aimed to assay the effect of polyphenol enriched blueberry preparation (PEBP) or non-fermented blueberry juice (NBJ) on the modulation of miRNA signature and the target proteins associated with different clinical-pathological characteristics of breast cancer such as stemness, invasion, and chemoresistance using breast cancer cell lines. To this end, 4T1 and MB-MDM-231 cell lines were exposed to NBJ or PEBP for 24 h. miRNA profiling was performed in breast cancer cell cultures, and RT-qPCR was undertaken to assay the expression of target miRNA. The expression of target proteins was examined by Western blotting. Profiling of miRNA revealed that several miRNAs associated with different clinical-pathological characteristics were differentially expressed in cells treated with PEBP. The validation study showed significant downregulation of oncogenic miR-210 expression in both 4T1 and MDA-MB-231 cells exposed to PEBP. In addition, expression of tumor suppressor miR-145 was significantly increased in both cell lines treated with PEBP. Western blot analysis showed a significant increase in the relative expression of FOXO1 in 4T1 and MDA-MB-231 cells exposed to PEBP and in MDA-MB-231 cells exposed to NBJ. Furthermore, a significant decrease was observed in the relative expression of N-RAS in 4T1 and MDA-MB-231 cells exposed to PEBP and in MDA-MB-231 cells exposed to NBJ. Our data indicate a potential chemoprevention role of PEBP through the modulation of miRNA expression, particularly miR-210 and miR-145, and protection against breast cancer development and progression. Thus, PEBP may represent a source for novel chemopreventative agents against breast cancer.

Intestinal microbiota and its association with colon cancer and red/processed meat consumption

The human colon harbors a high number of microorganisms that were reported to play a crucial role in colorectal carcinogenesis. In the recent decade, molecular detection and metabolomic techniques have expanded our knowledge on the role of specific microbial species in promoting tumorigenesis. In this study, we reviewed the association between microbial dysbiosis and colorectal carcinoma (CRC). Various microbial species and their association with colorectal tumorigenesis and red/processed meat consumption have been reviewed. The literature demonstrated a significant abundance of Fusobacterium nucleatum, Streptococcus bovis/gallolyticus, Escherichia coli, and Bacteroides fragilis in patients with adenoma or adenocarcinoma compared to healthy individuals. The mechanisms in which each organism was postulated to promote colon carcinogenesis were collated and summarized in this review. These include the microorganisms' ability to adhere to colon cells; modulate the inhibition of tumor suppressor genes, the activations of oncogenes, and genotoxicity; and activate downstream targets responsible for angiogenesis. The role of these microorganisms in conjugation with meat components including N-nitroso compounds, heterocyclic amines, and heme was also evident in multiple studies. The outcome of this review supports the role of red meat consumption in modulating CRC progression and the possibility of gut microbiome influencing the relationship between CRC and diet. The study also demonstrates that microbiota analysis could potentially complement existing screening methods when detecting colonic lesions.

Update on Strategies of Probiotics for the Prevention and Treatment of Colorectal Cancer

In recent years, with the further research on probiotics, probiotics may become an indispensable part in the prevention and treatment of colorectal cancer (CRC) in the future. As one of the most common cancer, the incidence of CRC is still rising in developing countries. Nowadays, there are lacking in prevention methods with low side effect. Surgery and chemotherapy, as the main treatment of CRC, bring many complications and affect the quality of life of patients. Probiotics has provided new ideas to solve these problems. Probiotics have anti-inflammatory, immune-enhancing, tumor-suppressing and other beneficial effects. Probiotics may provide some safe and effective prevention strategies for CRC. In addition, probiotics can also reduce the complications of surgery and chemotherapy, and improve the effectiveness of chemotherapy. Target administration with probiotics or probiotics cooperated with TRAIL to treat CRC. This article aims to review the mechanisms of probiotics for the prevention and treatment of CRC, as well as specific ways to use probiotics, in order to provide more new strategies for the prevention and treatment of CRC in the future, and reduce the incidence of and improve the quality of life of patients.

The Role of Probiotics in Cancer Prevention

Simple Summary

Cancer is considered one of the leading causes of human mortality in the world and is the subject of much research. The risk of developing cancer depends on genetic factors, as well as the body’s immune status. The intestinal microbiome plays very important role in maintaining homeostasis in the human body. Probiotics have gained increasing medical significance due to the beneficial effect on the human body associated with the prevention and support of the treatment of many chronic diseases, including cancer in the absence of side effects. The aim of this review was to summarize the knowledge about the effect of probiotic microorganisms in the prevention of cancer. There is a lot of evidence that the use of probiotics can play an important role in cancer prevention and support anti-cancer therapies.

Abstract

The gut microbiome can play important role in maintaining homeostasis in the human body. An imbalance in the gut microbiome can lead to pro-inflammatory immune responses and the initiation of disease processes, including cancer. The research results prove some strains of probiotics by modulating intestinal microbiota and immune response can be used for cancer prevention or/and as adjuvant treatment during anticancer chemotherapy. This review presents the latest advances in research into the effectiveness of probiotics in the prevention and treatment support of cancer. The described issues concern to the anticancer activity of probiotic microorganisms and their metabolites. In addition, we described the potential mechanisms of probiotic chemoprevention and the advisability of using probiotics.

The Protective Role of Probiotics against Colorectal Cancer

Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths worldwide and a major global public health problem. With the rapid development of the economy, the incidence of CRC has increased linearly. Accumulating evidence indicates that changes in the gut microenvironment, such as undesirable changes in the microbiota composition, provide favorable conditions for intestinal inflammation and shaping the tumor growth environment, whereas administration of certain probiotics can reverse this situation to a certain extent. This review summarizes the roles of probiotics in the regulation of CRC, such as enhancing the immune barrier, regulating the intestinal immune state, inhibiting pathogenic enzyme activity, regulating CRC cell proliferation and apoptosis, regulating redox homeostasis, and reprograming intestinal microbial composition. Abundant studies have provided a theoretical foundation for the roles of probiotics in CRC prevention and treatment, but their mechanisms of action remain to be investigated, and further clinical trials are warranted for the application of probiotics in the target population.

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.

Administration of Metabiotics Extracted From Probiotic Lactobacillus rhamnosus MD 14 Inhibit Experimental Colorectal Carcinogenesis by Targeting Wnt/β-Catenin Pathway

Background and Objective: The cellular microenvironment, diet, and lifestyle play a key role in the occurrence of colorectal cancer. Due to its rising trend, attempts are being made to devise novel biointerventions as adjunct to conventional therapies to prevent this deadly disease. “Metabiotics,” the beneficial metabolic signatures of probiotics are emerging as potential anticancer agent due to their ability to alter metabolic processes in the gut lumen and reduce the severity of colon carcinogenesis. Although beneficial attributes of metabiotics have been elucidated in vitro, yet their anticancer mechanism in vivo needs to be explored. Thus, the present study was performed to envisage anticancer potential of metabiotic extract obtained from indigenous probiotic, Lactobacillus rhamnosus MD 14, in early experimental colon carcinogenesis.

Materials and Methods: Sprague–Dawley rats were daily administered with low, medium, and high dose of metabiotic extract orally along with a single dose of weekly intraperitoneal injection of 1,2-dimethylhydrazine up to 6 weeks and monitored for the markers of early colon carcinogenesis.

Results: It was observed that the medium dose of metabiotic extract attenuated early colon carcinogenesis by reducing fecal procarcinogenic enzymes, oxidants, aberrant crypt foci, vis-à-vis downregulating oncogenes [K-ras, β-catenin, Cox-2, nuclear factor kappa B (NF-κB)] and upregulating tumor suppressor p53 gene leading to almost normal colon histology.

Conclusions: It can be suggested that metabiotics modulate experimental colorectal cancer and could be used as a promising alternative of probiotics, particularly in immunocompromised individuals.

Isolation, characterization and anti-inflammatory mechanism of probiotics in lipopolysaccharide-stimulated RAW 264.7 macrophages

Probiotics are known to modulate gut microbiota, intestinal barrier function and host immune response, but due to the species and strain specific response their mechanisms are not clearly understood. Thus, the present study was designed to isolate, assess the anti-inflammatory potential and underlying modulatory mechanisms of indigenous probiotics in murine macrophage cell line, RAW 264.7. Forty lactic acid bacteria (LAB) were isolated from different sources and monitored for their anti-inflammatory potential against lipopolysaccharide (LPS) induced inflammatory stress employing RAW 264.7 cells. Among these isolates, only four LAB isolates exhibited more than 90% nitric oxide inhibition and possessed the probiotic attributes. Further, these selected LAB isolates reduced the level of pro-inflammatory cytokines, TNF-α, IL-1β and IL-6, inhibited the phosphorylation of Mitogen Activated Protein Kinases (MAPKs) i.e. p38 MAPK, ERK1/2 and SAPK/JNK and expression of cyclooxygenase-2 (COX-2) in LPS stimulated RAW 264.7 cells. The in vitro analysis suggested that the selected probiotic isolates attenuated the LPS-induced inflammation by downregulating MAPK pathway vis-a-vis inhibiting COX-2 and can be employed as anti-inflammatory agents in various inflammatory diseases.

The Role of Probiotics in Colorectal Cancer Management

Colorectal cancer (CRC) is one of the most common cancerous diseases worldwide and causes leading cancer-associated deaths. Several factors are related to the incidence of CRC such as unhealthy diet and lifestyle, heredity, metabolic disorders, and genetic factors. Even though several advanced medical procedures are available for CRC treatment, the survival rates are poor with many adverse treatments associated side effects, which affects the quality of life. Probiotics are a well-known bioactive candidate for the treatment of several diseases and ill-health conditions. The recent scientific evidence suggested that probiotic supplementation protects the CRC patients from treatment-associated adverse effects. The manuscript summarizes the influence of probiotic supplementation on the health status of CRC patients and discusses the possible mechanism behind the protective effect of probiotics against CRC. The literature survey revealed that beneficial impact of probiotic supplementation depends on several factors such as strain, dosage, duration of the intervention, host physiology, and other food supplements. The probiotic intervention improves the microbiota, releases antimicrobials and anticarcinogenic agents, helps to remove carcinogens, and improves the intestinal permeability, tight junction function, and enzyme activity in CRC patients. Besides, not all probiotic strains exhibit anti-CRC activities; it is necessary to screen the potent strain for the development of a probiotic-based therapeutic agent to control or prevent the incidence of CRC.

Oral supplementation with lactobacilli to prevent colorectal cancer in preclinical models

Colorectal cancer (CRC) is still a major threat for public health, as it is the third most common cancer in men and the second in women and it ranks second among tumors in terms of mortality. Evidence from the last decades emphasizes the complex role of gut microbial composition in CRC development. Historically, it is believed that dairy products, a source of lactobacilli and other lactic acid bacteria, are beneficial for human health and help in preventing CRC. We searched online literature for trials evaluating the preventive role of lactobacilli in CRC animal models. Most of selected studied assessed a relevant role of lactobacilli in preventing CRC and precursor lesions. Mechanisms through which this effect was achieved are supposed to regard immunomodulation, regulation of apoptosis, gut microbial modulation, genes expression, reduction of oxidative stress and others. Lactobacilli oral supplementation is reported to be effective in preventing CRC in animal models, even if the underlying mechanisms of action are still not fully understood.

Isolation, characterization and identification of antigenotoxic and anticancerous indigenous probiotics and their prophylactic potential in experimental colon carcinogenesis

Colorectal cancer, the third most commonly diagnosed cancer, is a lifestyle disease where diet and gut microbiome contribute intricately in its initiation and progression. Prophylactic bio-interventions mainly probiotics offer an alternate approach towards reducing or delaying its progression. Therefore, the present study was designed wherein a robust protocol for the isolation, characterization, and identification of indigenous probiotics having antigenotoxic and anticancerous activity was followed along with their prophylactic potential assessment in early experimental colorectal carcinogenesis. Among forty-six isolated lactic acid bacterial strains, only three were selected on the basis of antigenotoxicity against N,N-Dimethyl dihydrazine dihydrochloride and 4-Nitroquinoline 1-oxide and probiotic attributes. All three selected probiotic strains exhibited anticancerous potential as is evident by the reduced Aberrant Crypt Foci, reduced fecal pH, enhanced fecal lactic acid bacteria and altered fecal enzymes (β-glucuronidase, nitroreductase, β-glucosidase) that modulated gut microbiota and microenvironment resulting into restored histoarchitecture of the colon. The results are a clear indicator of the prophylactic potential of selected indigenous probiotics which may be used as an alternative prophylactic biological therapy against colon carcinogenesis particularly in highly susceptible individuals.

Probiotic supplementation attenuates the aggressiveness of chemically induced colorectal tumor in rats

To evaluate the effect of a probiotic on the aggressiveness of a chemically induced colorectal tumor in rats. Twenty-five male Fisher 344 rats, 250 g, provided with feed and water ad libitum, were randomly divided into 5 groups (5 rats/group): G_Control, no treatment; G_Tumor, tumor induction; G_Tumor+5FU, tumor induction, 5-Fluorouracil applied; G_Tumor+Prob, induction of the tumor, supplemented with probiotic; G_{Tumor+5-FU+Prob}, tumor induction, 5-Fluorouracil applied, supplemented with probiotic. For tumor induction 20 mg/kg of 1,2-dimethylhydrazine was applied intraperitoneally over 4 weeks, followed by an interval of 15 days, and then repeated for a further 4 weeks. Five weeks after the final dose of the carcinogen, treatment was initiated with 5-Fluorouracil (15 mg/kg, intraperitoneally/week) and a commercial probiotic (1 × 10⁹ CFU, daily/gavage). Data were analyzed by One Way Variance Analysis and means compared by Dunnett's test. GraphPad Prism statistical software was used. The histopathological analyzes were evaluated by the chi-square test. A 5% type-I error was considered statistically significant. Compared with the G_Tumor, the G_Tumor+Prob (p < 0.0373) and G_{Tumor+5-FU+Prob} (p < 0.0003) demonstrated an attenuated effect on the aggressiveness of the colorectal tumor, with a reduction in the count of Aberrant Crypt foci; and a lower percentage of malignant neoplastic lesions in the G_Tumor+Prob (40% low grade tubular adenoma, 40% carcinoma in situ, 20% low grade adenocarcinoma) and G_{Tumor+5-FU+Prob} (40% low grade tubular adenoma and 60% carcinoma in situ). Probiotic supplementation has the potential to decrease the formation of aberrant crypts and ameliorate tumor malignancy, enhancing the antitumor effect of 5-Fluorouracil chemotherapy in colic segments.

Dysbiosis of the Gut Microbiome in Lung Cancer

Lung cancer (LC) is one of the most serious malignant tumors, which has the fastest growing morbidity and mortality worldwide. A role of the lung microbiota in LC pathogenesis has been analyzed, but a comparable role of the gut microbiota has not yet been investigated. In this study, the gut microbiota of 30 LC patients and 30 healthy controls were examined via next-generation sequencing of 16S rRNA and analyzed for diversity and biomarkers. We found that there was no decrease in significant microbial diversity (alpha diversity) in LC patients compared to controls (P observed = 0.1422), while the composition (beta diversity) differed significantly between patients and controls (phylum [stress = 0.153], class [stress = 0.16], order [stress = 0.146], family [stress = 0.153]). Controls had a higher abundance of the bacterial phylum Actinobacteria and genus Bifidobacterium, while patients with LC showed elevated levels of Enterococcus. These bacteria were found as possible biomarkers for LC. A decline of normal function of the gut microbiome in LC patients was also observed. These results provide the basic guidance for a systematic, multilayered assessment of the role of the gut microbiome in LC, which has a promising potential for early prevention and targeted intervention.

Probiotics and Colon Cancer

Literature has recently highlighted the enormous scientific interest on the relationship between the gut microbiota and colon cancer, and how the use of some selected probiotics can have a future impact on the adverse events which occur during this disease. Although there is no clear evidence to claim that probiotics are effective in people with cancer, recent reviews have found that probiotics can significantly reduce the incidence of diarrhea and the average frequency of daily bowel movements. However, most of this evidence needs to be more clinically convincing and further discussed. Undoubtedly, some probiotics, when properly dosed and administered, can have a strong rebalance effect on the gut microbiota and as a consequence a possible positive action on immune modulation of the gastrointestinal tract and on inflammation of the intestinal mucosa. Many recent findings indeed support the hypothesis that the daily use of some selected probiotics can be a feasible approach to effectively protect patients against the risk of some severe consequences due to radiation therapy or chemotherapy. This paper aims to review the most recent articles in order to consider a possible adjuvant approach for the use of certain well-balanced probiotics to help prevent colon cancer and the adverse effects caused by related therapies.

Beneficial effect of synbiotics on experimental colon cancer in rats

BACKGROUND/AIMS

The aim of this study was to investigate the influence of a synbiotic preparation (a mixture of six probiotics and a prebiotic) on aberrant crypt foci (ACF) formation, dysplasia, inflammation, and colitis-like lesions in experimental colon cancer in rats.

MATERIALS AND METHODS

Sixty male rats were categorized into three groups of 20 animals each. Group A was administered 1,2-dimethylydrazine, 15 mg/kg body weight (BW), once a week for 2 weeks. Group B was administered 1,2-dimethylydrazine at the same dose plus synbiotic, started after the second dose of carcinogen and lasted for 5 weeks. Group C was administered synbiotic plus carcinogen from the beginning of the experiment and lasted for 7 weeks. Animals were killed at the end of week 7.

RESULTS

At the end of the experiment, the animals that received carcinogen plus the synbiotic had 100%, whereas the animals that received only carcinogen has 70% survival. Animals of groups B and C had significantly lower percentage of inflammation, colitis-like lesions, and ACF dysplasia than animals of group A, whereas those of group C had the least pathological lesions.

CONCLUSION

Synbiotics seem to protect against the appearance of preneoplastic colon lesions in rats. The results of this experimental study suggest that treatment with a synbiotic preparation exerts significant antimutagenic properties against the development of preneoplastic lesions in rats.

Immunotherapeutic advances in gastrointestinal malignancies

Cancer is an important global issue with increasing incidence and mortality, placing a substantial burden on the healthcare system. Colorectal cancer is the third most common cancer diagnosed among men and women in US. It is estimated that in 2018 there will be 319,160 new diagnosis and 160,820 deaths related to cancer of the digestive system including both genders in the United States alone. Considering limited success of chemotherapy, radiotherapy, and surgery in treatment of these cancer patients, new therapeutic avenues are under constant investigation. Therapy options have consistently moved away from typical cytotoxic chemotherapy where patients with a given type and stage of the disease were treated similarly, to an individualized approach where a tumor is defined by its specific tissue characteristics /epigenetic profile, protein expression and genetic mutations. This review takes a deeper look at the immune-biological aspects of cancers in the gastrointestinal tract (entire digestive tract extending from esophagus/stomach to rectum, including pancreatico-biliary apparatus) and discusses the different treatment modalities that are available or being developed to target the immune system for better disease outcome.

Probiotics in the Treatment of Colorectal Cancer

The human microbiome plays many roles in inflammation, drug metabolism, and even the development of cancer that we are only beginning to understand. Colorectal cancer has been a focus for study in this field as its pathogenesis and its response to treatment have both been linked to the functioning of microbiota. This literature review evaluates the animal and human studies that have explored this relationship. By manipulating the microbiome with interventions such as probiotic administration, we may be able to reduce colorectal cancer risk and improve the safety and effectiveness of cancer therapy even though additional clinical research is still necessary.

Probiotics (Lactobacillus acidophilus and Lactobacillus rhamnosus GG) in Conjunction with Celecoxib (selective COX-2 inhibitor) Modulated DMH-Induced Early Experimental Colon Carcinogenesis

Epidemiological and experimental observations have shown that nonsteroidal anti-inflammatory drugs especially selective cyclooxygenase-2 (COX-2) inhibitors and probiotics reduce the incidence risk of colon cancer. Therefore, the present study was designed to assess the prophylactic potentials of probiotics (Lactobacillus acidophilus and Lactobacillus rhamnosus GG) in conjunction with celecoxib, a selective cox-2 inhibitor in 1,2 dimethylhydrazine dihydrochloride (DMH)-induced experimental colon carcinogenesis, a well-established, well appreciated and widely used model for colorectal cancer that shares many similarities to human sporadic colorectal cancer with respect to response to some promotional and preventive agents. More specifically, it was observed that L. rhamnosus GG + celecoxib + DMH-treated animals had significantly reduced aberrant crypt foci (ACF) count and the expression of procarcinogenic molecular markers (β-catenin, NF-κB, and COX-2) in early experimental colon carcinogenesis compared with probiotic-DMH, celecoxib-DMH or DMH-treated animals. This is the first ever such study to demonstrate that probiotic in conjunction with celecoxib can be opted as an alternate prophylactic strategy in highly susceptible individuals to reduce both the incidence and severity of the life style diseases as prevention is better than cure.

Microbiota modification by probiotic supplementation reduces colitis associated colon cancer in mice

AIM

To investigate the effect of probiotic supplementation during the development of an experimental model of colitis associated colon cancer (CAC).

METHODS

C57BL/6 mice received an intraperitoneal injection of azoxymethane (10 mg/kg), followed by three cycles of sodium dextran sulphate diluted in water (5% w/v). Probiotic group received daily a mixture of Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium bifidum. Microbiota composition was assessed by 16S rRNA Illumina HiSeq sequencing. Colon samples were collected for histological analysis. Tumor cytokines was assessed by Real Time-PCR (Polymerase Chain Reaction); and serum cytokines by Multiplex assay. All tests were two-sided. The level of significance was set at P < 0.05. Graphs were generated and statistical analysis performed using the software GraphPad Prism 5.0. The project was approved by the institutional review board committee.

RESULTS

At day 60 after azoxymethane injection, the mean number of tumours in the probiotic group was 40% lower than that in the control group, and the probiotic group exhibited tumours of smaller size (< 2 mm) (P < 0.05). There was no difference in richness and diversity between groups. However, there was a significant difference in beta diversity in the multidimensional scaling analysis. The abundance of the genera Lactobacillus, Bifidobacterium, Allobaculum, Clostridium XI and Clostridium XVIII increased in the probiotic group (P < 0.05). The microbial change was accompanied by reduced colitis, demonstrated by a 46% reduction in the colon inflammatory index; reduced expression of the serum chemokines RANTES and Eotaxin; decreased p-IKK and TNF-α and increased IL-10 expression in the colon.

CONCLUSION

Our results suggest a potential chemopreventive effect of probiotic on CAC. Probiotic supplementation changes microbiota structure and regulates the inflammatory response, reducing colitis and preventing CAC.

Antitumor mechanisms of bifidobacteria

Cancer remains one of the most common causes of mortality globally. Chemotherapy, one of the major treatment strategies for cancer, primarily functions by targeting the cancer cells and affecting them physiologically, but also affects normal cells, which is a major concern at present. Therefore, adverse effects of chemotherapy drugs, including myelosuppression and liver and kidney damage, are of concern. Now, microbial products have attracted attention in cancer treatment research. Notably, carcinogenesis is considered to be associated with microbial dysbiosis, particularly the positive antitumor effects of bifidobacteria. Although there remains a substantial amount to be understood about the regulation of bifidobacteria, bifidobacteria remain an attractive and novel source of cancer therapeutics. The present review focuses on introducing the latest information on the antitumor effects of bifidobacteria and to propose future strategies for using bifidobacteria in the development of cancer therapeutics.

The microbiome in dermatology

The skin supports a delicate ecosystem of microbial elements. Although the skin typically acts as a barrier, these microbes interact with the internal body environment and imbalances from the "healthy" state that have been linked to several dermatologic diseases. Understanding the changes in microbial flora in disease states allows for the potential to treat by restoring equilibrium. With the rising popularity of holistic and natural consumerism, prebiotics, probiotics, symbiotic, and other therapies are under study to find alternative treatments to these skin disorders through manipulation or supplementation of the microbiome.

Protective Effect of Lactobacillus casei on DMH-Induced Colon Carcinogenesis in Mice

The administration of probiotics is a promising approach to reduce the prevalence of colon cancer, a multifactorial disease, with hereditary factors, as well as environmental lifestyle-related risk factors. Biogenic polyamines, putrescine, spermidine, and spermine are small cationic molecules with great roles in cell proliferation and differentiation as well as regulation of gene expression. Ornithine decarboxylase is the first rate-limiting enzyme for polyamine synthesis, and upregulation of ornithine decarboxylase activity and polyamine metabolism has been associated with abnormal cell proliferation. This paper is focused on studying the protective role of Lactobacillus casei ATCC 393 in a chemically induced mouse model of colon carcinogenesis, directing our attention on aberrant crypt foci as preneoplastic markers, and on polyamine metabolism as a possible key player in carcinogenesis. BALB/c mice were administered 1,2-dimethylhydrazine dihydrochloride (DMH) to induce colon cancer (20 mg/kg body weight, subcutaneous, twice a week for 24 weeks). L. casei ATCC 393 was given orally (10⁶ CFU, twice a week), 2 weeks before DMH administration. Hematoxylin and eosin staining, high-performance liquid chromatography, and Western blotting were used to evaluate aberrant crypt foci, urinary polyamines, and ornithine decarboxylase expression in the colon. The experimental data showed that the preventive administration of L. casei ATCC 393 may delay the onset of cancer as it significantly reduced the number of DMH-induced aberrant crypt foci, the levels of putrescine, and the expression of ornithine decarboxylase. Hence, this probiotic strain has a prospective role in protection against colon carcinogenesis, and its antimutagenic activity may be associated with the maintenance of polyamine metabolism.

Pretreatment with probiotic Bifico ameliorates colitis-associated cancer in mice: Transcriptome and gut flora profiling

Individuals with inflammatory bowel disease are at high risk of developing colitis‐associated cancer (CAC). Strategies to block the process from inflammatory bowel disease to CAC should be considered. In the experiment, we aim to explore the chemopreventive efficacy of the probiotic cocktail Bifico and its potential mechanism in azoxymethane and dextran sodium sulphate‐induced CAC in mice. Oral pretreatment of Bifico was adopted to evaluate its protective effect. The colorectums of 35 C57BL/6 mice were collected and examined for the degree of inflammation and tumorigenesis. Comparative 16S rRNA sequencing was carried out to observe Bifico‐target alterations in gene expression and microbiota structure. We found that pretreatment of Bifico alleviated intestinal inflammation and reduced tumor formation. Furthermore, we identified a subset of genes as potential targets of Bifico treatment, including CXCL1,CXCL2,CXCL3, and CXCL5, which are all ligands of C‐X‐C motif receptor 2 (CXCR2). The 16S rRNA sequencing showed that Bifico decreased the abundance of genera Desulfovibrio, Mucispirillum, and Odoribacter, and a bloom of genus Lactobacillus was detected. Notably, we found that an abundance of these Bifico‐target taxa was significantly associated with the expression of CXCR2 ligand genes. Our studies indicate that Bifico, given orally, can ameliorate CAC in mice through intervening with the possible link between Desulfovibrio, Mucispirillum, Odoribacter, Lactobacillus, and CXCR2 signaling.

Dietary components that counteract the increased risk of colorectal cancer related to red meat consumption

Western-style diets are associated with an increased risk of colorectal cancer (CRC). In particular, a strong correlation has been documented between CRC and the consumption of large amounts of red meat, especially processed red meat. Compared with white meat, red meat contains high levels of haem iron, a molecule that can exert a variety of genotoxic and other adverse effects on the colonic epithelium. According to current international guidelines, the reduction of red meat intake combined with the consumption of food containing antioxidant and chemoprotective substances may significantly reduce the risk of developing CRC. The dietary strategies that can help to contrast the harmful effects of haem iron are reported and discussed in this review.

Gut Microbe-Mediated Suppression of Inflammation-Associated Colon Carcinogenesis by Luminal Histamine Production

Microbiome-mediated suppression of carcinogenesis may open new avenues for identification of therapeutic targets and prevention strategies in oncology. Histidine decarboxylase (HDC) deficiency has been shown to promote inflammation-associated colorectal cancer by accumulation of CD11b⁺Gr-1⁺ immature myeloid cells, indicating a potential antitumorigenic effect of histamine. Here, we demonstrate that administration of hdc⁺Lactobacillus reuteri in the gut resulted in luminal hdc gene expression and histamine production in the intestines of Hdc^-/- mice. This histamine-producing probiotic decreased the number and size of colon tumors and colonic uptake of [¹⁸F]-fluorodeoxyglucose by positron emission tomography in Hdc^-/- mice. Administration of L. reuteri suppressed keratinocyte chemoattractant (KC), Il22, Il6, Tnf, and IL1α gene expression in the colonic mucosa and reduced the amounts of proinflammatory, cancer-associated cytokines, keratinocyte chemoattractant, IL-22, and IL-6, in plasma. Histamine-generating L. reuteri also decreased the relative numbers of splenic CD11b⁺Gr-1⁺ immature myeloid cells. Furthermore, an isogenic HDC-deficient L. reuteri mutant that was unable to generate histamine did not suppress carcinogenesis, indicating a significant role of the cometabolite, histamine, in suppression of chronic intestinal inflammation and colorectal tumorigenesis. These findings link luminal conversion of amino acids to biogenic amines by gut microbes and probiotic-mediated suppression of colorectal neoplasia.

Lactobacillus rhamnosus ATCC 7469 exopolysaccharides synergizes with low level ionizing radiation to modulate signaling molecular targets in colorectal carcinogenesis in rats

Combination therapy that targets cellular signaling pathway represents an alternative therapy for the treatment of colon cancer (CRC). The present study was therefore aimed to investigate the probable interaction of Lactobacillus rhamnosus ATCC 7469 exopolysaccharides (EPS) with low level ionizing γ radiation (γ-R) exposure against dimethylhydrazine (DMH)- induced colorectal carcinogenesis in rats. Colon cancer was induced with 20mg DMH/kg BW. Rats received daily by gastric gavage 100mg EPS/Kg BW concomitant with 1Gy γ-R over two months. Colonic oxidative and inflammatory stresses were assessed. The change in the expression of p-p38 MAPK, p-STAT3, β-catenin, NF-kB, COX-2 and iNOS was evaluated by western blotting and q-PCR. It was found that DMH treatment significantly induced colon oxidative injury accompanied by inflammatory disturbance along with increased protein expression of the targeted signaling factors p-p38 MAPK, p-STAT3 and β-catenin. The mRNA gene expression of NF-kB, COX-2 and iNOS was significantly higher in DMH-treated animals. It's worthy to note that colon tissues with DMH treatment showed significant dysplasia and anaplasia of the glandular mucosal lining epithelium with loses of goblet cells formation, pleomorphism in the cells and hyperchromachia in nuclei. Interestingly, EPS treatment with γ-R exposure showed statistically significant amelioration of the oxidative and inflammatory biomarkers with modulated signaling molecular factors accompanied by improved histological structure against DMH-induced CRC. In conclusion, our findings showed that Lactobacillus rhamnosus ATCC 7469 EPS with low level γ-R in synergistic interaction are efficacious control against CRC progression throughout the modulation of key signaling growth factors associated with inflammation via antioxidant mediated anti-inflammatory and anti-proliferative activities.

Lactobacillus casei Zhang and vitamin K2 prevent intestinal tumorigenesis in mice via adiponectin-elevated different signaling pathways

The incidence of colon cancer has increased considerably and the intestinal microbiota participate in the development of colon cancer. We showed that the L. casei Zhang or vitamin K2 (Menaquinone-7) intervention significantly alleviated intestinal tumor burden in mice. This was associated with increased serum adiponectin levels in both treatments. But osteocalcin level was only increased by L. casei Zhang. Furthermore, the anti-carcinogenic actions of L. casei Zhang were mediated by hepatic Chloride channel-3(CLCN3)/Nuclear Factor Kappa B(NF-κB) and intestinal Claudin15/Chloride intracellular channel 4(CLIC4)/Transforming Growth Factor Beta(TGF-β) signaling, while the vitamin K2 effect involved a hepatic Vitamin D Receptor(VDR)-phosphorylated AMPK signaling pathway. Fecal DNA sequencing by the Pacbio RSII method revealed there was significantly lower Helicobacter apodemus, Helicobacter mesocricetorum, Allobaculum stercoricanis and Adlercreutzia equolifaciens following both interventions compared to the model group. Moreover, different caecum acetic acid and butyric acid levels and enrichment of other specific microbes also determined the activity of the different regulatory pathways. Together these data show that L. casei Zhang and Vitamin K2 can suppress gut risk microbes and promote beneficial microbial metabolites to reduce colonic tumor development in mice.

Capacity of lactic acid bacteria in immunity enhancement and cancer prevention

Lactic acid bacteria are associated with the human gastrointestinal tract. They are important for maintaining the balance of microflora in the human gut. An increasing number of published research reports in recent years have denoted the importance of producing interferon-gamma and IgA for treatment of disease. These agents can enhance the specific and nonspecific immune systems that are dependent on specific bacterial strains. The mechanisms of these effects were revealed in this investigation, where the cell walls of these bacteria were modulated by the cytokine pathways, while the whole bacterial cell mediated the host cell immune system and regulated the production of tumor necrosis factors and interleukins. A supplement of highly active lactic acid bacteria strains provided significant potential to enhance host's immunity, offering prevention from many diseases including some cancers. This review summarizes the current understanding of the function of lactic acid bacteria immunity enhancement and cancer prevention.

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.