Preclinical Evidence of Probiotics in Colorectal Carcinogenesis: A Systematic Review

Current and emerging therapeutic approaches for colorectal cancer: A comprehensive review

Colorectal cancer (CRC) affects 1 in 23 males and 1 in 25 females, making it the third most common cancer. With roughly 608000 deaths worldwide, CRC accounts for 8% of all cancer-related deaths, making it the second most common cause of death due to cancer. Standard and conventional CRC treatments include surgical expurgation for resectable CRC and radiotherapy, chemotherapy, immunotherapy, and their combinational regimen for non-resectable CRC. Despite these tactics, nearly half of patients develop incurable recurring CRC. Cancer cells resist the effects of chemotherapeutic drugs in a variety of ways, including drug inactivation, drug influx and efflux modifications, and ATP-binding cassette transporter overexpression. These constraints necessitate the development of new target-specific therapeutic strategies. Emerging therapeutic approaches, such as targeted immune boosting therapies, non-coding RNA-based therapies, probiotics, natural products, oncolytic viral therapies, and biomarker-driven therapies, have shown promising results in preclinical and clinical studies. We tethered the entire evolutionary trends in the development of CRC treatments in this review and discussed the potential of new therapies and how they might be used in conjunction with conventional treatments as well as their advantages and drawbacks as future medicines.

Substituting meat for mycoprotein reduces genotoxicity and increases the abundance of beneficial microbes in the gut: Mycomeat, a randomised crossover control trial

PURPOSE

The high-meat, low-fibre Western diet is strongly associated with colorectal cancer risk. Mycoprotein, produced from Fusarium venanatum, has been sold as a high-fibre alternative to meat for decades. Hitherto, the effects of mycoprotein in the human bowel have not been well considered. Here, we explored the effects of replacing a high red and processed meat intake with mycoprotein on markers of intestinal genotoxicity and gut health.

METHODS

Mycomeat (clinicaltrials.gov NCT03944421) was an investigator-blind, randomised, crossover dietary intervention trial. Twenty healthy male adults were randomised to consume 240 g day^-1 red and processed meat for 2 weeks, with crossover to 2 weeks 240 g day^-1 mycoprotein, separated by a 4-week washout period. Primary end points were faecal genotoxicity and genotoxins, while secondary end points comprised changes in gut microbiome composition and activity.

RESULTS

The meat diet increased faecal genotoxicity and nitroso compound excretion, whereas the weight-matched consumption of mycoprotein decreased faecal genotoxicity and nitroso compounds. In addition, meat intake increased the abundance of Oscillobacter and Alistipes, whereas mycoprotein consumption increased Lactobacilli, Roseburia and Akkermansia, as well as the excretion of short chain fatty acids.

CONCLUSION

Replacing red and processed meat with the Fusarium-based meat alternative, mycoprotein, significantly reduces faecal genotoxicity and genotoxin excretion and increases the abundance of microbial genera with putative health benefits in the gut. This work demonstrates that mycoprotein may be a beneficial alternative to meat within the context of gut health and colorectal cancer prevention.

Survival effect of probiotics in a rat model of colorectal cancer treated with capecitabine

BACKGROUND

Probiotics are used to manage a number of gastrointestinal disorders due to their beneficial properties. Clinical reports showed that probiotics also improve the life quality of patients with colorectal cancer (CRC) subjected to oncologic treatment. In a CRC animal model, probiotics supplementation has the potential to decrease the formation of aberrant crypts and ameliorate tumor malignancy, enhancing the antitumor effect of 5-fluorouracil (5-FU) chemotherapy. Based on these data, we hypothesize that the administration of probiotics impact positively in the overall survival and life quality of rats with CRC under the treatment of capecitabine, which is the pro drug of 5-FU.

AIM

To evaluate the probiotics effects in a rat CRC model treated with capecitabine and followed until the end of life.

METHODS

1,2-Dimethylhidrazine dihydrochloride (1,2-DMH) was employed as carcinogen inductor of CRC. Fifty male Wistar-Lewis rats were randomly assigned to one of five following groups: Control (n = 5), Control + probiotics (Control-P group, n = 5), 1,2-DMH alone (DMH group, n = 10), 1,2-DMH + capecitabine (DMH-C group, n = 10), 1,2-DMH + probiotics (DMH-P group, n = 10) and 1,2-DMH + capecitabine + probiotics (DMH-C-P group, n = 10). All parametric data were expressed as the mean ± SD. The statistical significance of differences was analyzed using one-way ANOVA. Data were analyzed with InfoStat software. The results were considered statistically significant at P < 0.05. Overall survival was evaluated with the Kaplan-Meier estimator with the log-rank test.

RESULTS

The data of mean overall survival for DMH, DMH-P, DMH-C, DMH-C-P, Control and Control-P groups were 250 d [95% confidence interval (CI): 242.5-253.1], 268 d (95%CI: 246.3-271.4), 380 d (95%CI: 337.8-421.9), 480 d (95%CI: 436.9-530.7), 588 d (95%CI: 565.8-609.3) and 590 d (95%CI: 564.3-612.9), respectively, with a significant difference between DMH-C and DMH-C-P groups (P = 0.001). Comparing all groups by Kaplan-Meier estimator, we found a significantly different in the overall survival of DMH and DMH-P groups respect to DMH-C (P = 0.001) and DMH-C-P (P = 0.001) groups; interestingly, there were no meaningful differences between Control, Control-P and DMH-C-P groups (P = 0.012). The tendency of change in body weight gain of the rats at 90 d of finishing DMH administration was similar in Control group compared with DMH-C and DMH-C-P groups; however, and of relevance, DMH-C-P group has experienced a higher body weight gain at the end of animal’s life than DMH-C group (P = 0.001). In DMH-C-P group we found a positive effect of probiotics in clinical manifestations since diarrhea, constipation and blood stool were absenting. Also, the tumor burden was lower in DMH-C-P than DMH-C, DMH-P or DMH groups (1.25 vs 1.81 vs 3.9 vs 4.8 cm², respectively). DMH-C and DMH-C-P groups showed only mucinous carcinoma type while in other DMH groups the tumor types were variable. However, mucinous carcinoma from DMH-C-P group showed invasion until muscularis propria layer. Interestingly, metastatic lymph node was observed in DMH, DMH-C and DMH-P groups but not in DMH-C-P. All animals in Control group died from natural causes without objective injuries. All animals of DMH and DMH-P groups died from tumor complications (i.e., obstruction or intestinal perforation); however, this cause was seen only in 44.5% of DMH-C and DMH-C-P groups

CONCLUSION

Probiotics administration improves life quality of rats with CRC under capecitabine treatment and also has a positive effect in the overall survival of these animals treated with this drug.

Probiotics: A Promising Candidate for Management of Colorectal Cancer

Colorectal cancer (CRC) is the World's third most frequently diagnosed cancer type. It accounted for about 9.4% mortality out of the total incidences of cancer in the year 2020. According to estimated facts by World Health Organization (WHO), by 2030, 27 million new CRC cases, 17 million deaths, and around 75 million people living with the disease will appear. The facts and evidence that establish a link between the intestinal microflora and the occurrence of CRC are quite intuitive. Current shortcomings of chemo- and radiotherapies and the unavailability of appropriate treatment strategies for CRC are becoming the driving force to search for an alternative approach for the prevention, therapy, and management of CRC. Probiotics have been used for a long time due to their beneficial health effects, and now, it has become a popular candidate for the preventive and therapeutic treatment of CRC. The probiotics adopt different strategies such as the improvement of the intestinal barrier function, balancing of natural gut microflora, secretion of anticancer compounds, and degradation of carcinogenic compounds, which are useful in the prophylactic treatment of CRC. The pro-apoptotic ability of probiotics against cancerous cells makes them a potential therapeutic candidate against cancer diseases. Moreover, the immunomodulatory properties of probiotics have created interest among researchers to explore the therapeutic strategy by activating the immune system against cancerous cells. The present review discusses in detail different strategies and mechanisms of probiotics towards the prevention and treatment of CRC.

Probiotics supplementation in patients with colorectal cancer: a systematic review of randomized controlled trials

CONTEXT

Colorectal cancer (CRC) is a leading cause of cancer deaths. Recently, much attention has been given to the microbiome and probiotics as preventive and therapeutic approaches to CRC and the mechanisms involved.

OBJECTIVES

To interpret the findings of randomized controlled trials (RCTs) of probiotics relative to patients with CRC and to outline challenges of and future directions for using probiotics in the management and prevention of CRC.

DATA SOURCES

Web of Science, PubMed, ProQuest, Wile, y and Scopus databases were searched systematically from January 17-20, 2020, in accordance with PRISMA guidelines.

STUDY SELECTION

Primacy RCTs that reported the effects of administration to patients with CRC of a probiotic vs a placebo were eligible to be included.

DATA EXTRACTION

The studies were screened and selected independently by 2 authors on the basis of prespecified inclusion and exclusion criteria. The data extraction and risk-of-bias assessment were also performed independently by 2 authors.

RESULTS

A total of 23 RCTs were eligible for inclusion. Probiotics supplementation in patients with CRC improved their quality of life, enhanced gut microbiota diversity, reduced postoperative infection complications, and inhibited pro-inflammatory cytokine production. The use of certain probiotics in patients with CRC also reduced the side effects of chemotherapy, improved the outcomes of surgery, shortened hospital stays, and decreased the risk of death. Bifidobacteria and Lactobacillus were the common probiotics used across all studies.

CONCLUSION

Probiotics have beneficial effects in patients with CRC regardless of the stage of cancer. There is an opportunity for probiotics to be used in mainstream health care as a therapy in the fight against CRC, especially in early stages; however, larger clinical trialsof selected or a cocktail of probiotics are needed to confirm the efficacy, dosage, and interactions with chemotherapeutics agents.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020166865.

Role of probiotics in patients with colorectal cancer: a systematic review protocol of randomised controlled trial studies

INTRODUCTION

Colorectal cancer is one of the leading causes of cancer-related morbidity worldwide and it has been reported to be associated with poor lifestyle habits which include excess tobacco and alcohol intake as well as genetics and age factors. Probiotics such as the lactic acid bacteria and Bifidobacterium as well as probiotic containing foods (kombucha, kefir, miso etc) have received lots of attention as anticancer agents for prevention and treatment. The effects of the administration of probiotics to patients with colorectal cancer is the primary goal of this systematic review. The overall aim is to assess how the use of probiotics in patients with colorectal cancer helps in the management of colorectal cancer and its effect on the diversity of gut microbiota. The final systematic review will provide a comprehensive evidence base for the use and efficacy of probiotics in patient with colorectal cancer care.

METHODS AND ANALYSIS

The systematic review, will be conducted by extensively searching different databases such as PubMed, Web of Science, Scopus, Wiley and ProQuest to identify randomised controlled trials (with no time frame) which relate to the administration of probiotics to patients with colorectal cancer. The search strategy will include words like colorectal cancer, probiotics, Bifidobacterium, clinical trials etc. A systematic search of databases was performed between 17 and 20 January 2020. Two reviewers will independently review the studies and also search the reference lists of the eligible studies to obtain more references. Data will be extracted from the eligible studies using standardised data extraction form. After assessing the risk of bias, qualitative analysis will be used to synthesise the systematic review.

ETHICS AND DISSEMINATION

This is a protocol for a systematic review; therefore, it doesn't require any ethics approval. We intend to disseminate the protocol in a peer reviewed journal.

A Fragile Balance: The Important Role of the Intestinal Microbiota in the Prevention and Management of Colorectal Cancer

BACKGROUND

Colorectal cancer is the second leading cause of cancer-related death worldwide. In recent years, researchers have focussed on the role of the intestinal microbiota in both the prevention and the treatment of colorectal cancer.

SUMMARY

The evidence in the literature supports that there is a fragile balance between different species of bacteria in the human gut. A disturbance of this balance towards increased levels of the bacteria Fusobacterium nucleatum and Bacteroides fragilis is associated with an increased risk of colorectal cancer. The mechanisms involved include the release of toxins which activate inflammation and the regulation of specific miRNAs (with an increase in the expression of oncogenic miRNAs and a decrease in the expression of tumour suppressor miRNAs), thereby increasing cell proliferation and leading to tumorigenesis. On the other hand, Lactobacillus and Bifidobacterium have a protective effect against the development of colorectal cancer through mechanisms that involve an increase in the levels of anticarcinogenic metabolites such as butyrate and a decrease in the activity of proinflammatory pathways. Even though preliminary studies support that the use of probiotics in the prevention and management of colorectal cancer is promising, more research is needed in this field. Key Message: The association between the intestinal microbiota, diet and colorectal cancer remains an active area of research with expected future applications in the use of probiotics for the prevention and management of this significant disease.