An interleukin 2/sodium butyrate combination as immunotherapy for rat colon cancer peritoneal carcinomatosis

Fatty Acids as a Tool to Boost Cancer Immunotherapy Efficacy

Although immunotherapy represents one of the most potent therapeutic anti-cancer approaches, only a limited number of patients shows clinical benefit. Recent evidence suggests that patients' nutritional status plays a major role in immunotherapy outcome. Fatty acids are essential in a balanced diet and well-known to influence the immune response. Moreover, short-chain fatty acids (SCFAs) show beneficial effects in metabolic disorders as well as in cancer and polyunsaturated fatty acids (PUFAs) contribute to body weight and fat free mass preservation in cancer patients. In line with these data, several studies imply a role for SCFAs and PUFAs in boosting the outcome of immunotherapy. In this review, we specifically focus on mechanistic data showing that SCFAs modulate the immunogenicity of tumor cells and we discuss the direct effects of SCFAs and PUFAs on the immune system in the context of cancer. We provide preclinical and clinical evidence indicating that SCFAs and PUFAs may have the potential to boost immunotherapy efficacy. Finally, we describe the challenges and address opportunities for successful application of nutritional interventions focusing on SCFAs and PUFAs to increase the therapeutic potential of immunotherapeutic approaches for cancer.

In vitro digestibility and prebiotic activities of a bioactive polysaccharide from Moringa oleifera leaves

In this study, the digestion and fermentation properties of a bioactive polysaccharide (MOP-2) purified from Moringa oleifera leaves and its impact on the human colonic microbiota were determined using simulated saliva-gastrointestinal digestion and human fecal fermentation models in vitro. The results showed that the simulated saliva and gastric juices had no effect on the average molecular weight (MW) of MOP-2. The MW of MOP-2 slightly decreased from 155.29 to 145.02 kDa during intestinal digestion, and the reducing sugar content increased from 0.159 to 0.234 mg/ml, indicating that MOP-2 was partially degraded during intestinal digestion. During fermentation, MOP-2 was largely used by human fecal inoculums. Notably, MOP-2 could significantly regulate the structure of the microbial community by improving the relative abundances of some beneficial gut microbiota, such as Phascolarctobacterium, Coprococcus, Roseburia, and Bacteroides. Additionally, after fermentation for 48 hr, MOP-2 could significantly improve the production of short-chain fatty acids, especially n-butyric acid, acetic acid, propionic acid, and n-valeric acid. These results suggested that MOP-2 could potentially be a gut microbiota manipulator aimed at promoting gut health. PRACTICAL APPLICATIONS: Gut microbial community is an important part of the human intestinal environment. The health of gut microbiota is closely associated with host heath. This work reported that a polysaccharide (MOP-2) purified from Moringa oleifera leaves could modulate the microbial structure by improving the relative abundances of some beneficial gut microbiota, which provided useful information for the application of MOP-2 as a prebiotic additive in food industry.

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.

Impact of HDAC Inhibitors on Protein Quality Control Systems: Consequences for Precision Medicine in Malignant Disease

Lysine acetylation is one of the major posttranslational modifications (PTM) in human cells and thus needs to be tightly regulated by the writers of this process, the histone acetyl transferases (HAT), and the erasers, the histone deacetylases (HDAC). Acetylation plays a crucial role in cell signaling, cell cycle control and in epigenetic regulation of gene expression. Bromodomain (BRD)-containing proteins are readers of the acetylation mark, enabling them to transduce the modification signal. HDAC inhibitors (HDACi) have been proven to be efficient in hematologic malignancies with four of them being approved by the FDA. However, the mechanisms by which HDACi exert their cytotoxicity are only partly resolved. It is likely that HDACi alter the acetylation pattern of cytoplasmic proteins, contributing to their anti-cancer potential. Recently, it has been demonstrated that various protein quality control (PQC) systems are involved in recognizing the altered acetylation pattern upon HDACi treatment. In particular, molecular chaperones, the ubiquitin proteasome system (UPS) and autophagy are able to sense the structurally changed proteins, providing additional targets. Recent clinical studies of novel HDACi have proven that proteins of the UPS may serve as biomarkers for stratifying patient groups under HDACi regimes. In addition, members of the PQC systems have been shown to modify the epigenetic readout of HDACi treated cells and alter proteostasis in the nucleus, thus contributing to changing gene expression profiles. Bromodomain (BRD)-containing proteins seem to play a potent role in transducing the signaling process initiating apoptosis, and many clinical trials are under way to test BRD inhibitors. Finally, it has been demonstrated that HDACi treatment leads to protein misfolding and aggregation, which may explain the effect of panobinostat, the latest FDA approved HDACi, in combination with the proteasome inhibitor bortezomib in multiple myeloma. Therefore, proteins of these PQC systems provide valuable targets for precision medicine in cancer. In this review, we give an overview of the impact of HDACi treatment on PQC systems and their implications for malignant disease. We exemplify the development of novel HDACi and how affected proteins belonging to PQC can be used to determine molecular signatures and utilized in precision medicine.

Intestinal Microbiota Is Altered in Patients with Gastric Cancer from Shanxi Province, China

BACKGROUND

Many diseases have been associated with intestinal microbial dysbiosis. Host-microbial interactions regulate immune function, which influences the development of gastric cancer.

AIMS

The aims were to investigate the characteristics of intestinal microbiota composition in gastric cancer patients and correlations between the intestinal microbiota and cellular immunity.

METHODS

Fecal samples were collected from 116 gastric cancer patients and 88 healthy controls from Shanxi Province, China. The intestinal microbiota was investigated by 16S rRNA gene sequencing. Peripheral blood samples were also collected from the 66 gastric cancer patients and 46 healthy controls. The populations of peripheral T lymphocyte subpopulations and NK cells were analyzed by flow cytometry.

RESULTS

The intestinal microbiota in gastric cancer patients was characterized by increased species richness, decreased butyrate-producing bacteria, and the enrichment of other symbiotic bacteria, especially Lactobacillus, Escherichia, and Klebsiella. Lactobacillus and Lachnospira were key species in the network of gastric cancer-associated bacterial genera. The combination of the genera Lachnospira, Lactobacillus, Streptococcus, Veillonella, and Tyzzerella_3 showed good performance in distinguishing gastric cancer patients from healthy controls. There was no significant difference in enterotype distribution between healthy controls and gastric cancer patients. The percentage of CD3⁺ T cells was positively correlated with the abundance of Lactobacillus and Streptococcus, and CD3⁺ T cells, CD4⁺ T cells, and NK cells were associated with Lachnospiraceae taxa.

CONCLUSIONS

Our study revealed a dysbiotic intestinal microbiota in gastric cancer patients. The abundance of some intestinal bacterial genera was correlated with the population of peripheral immune cells.

Bacterial ghosts as adjuvant to oxaliplatin chemotherapy in colorectal carcinomatosis

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer mortality worldwide. At late stage of the disease CRC often shows (multiple) metastatic lesions in the peritoneal cavity which cannot be efficiently targeted by systemic chemotherapy. This is one major factor contributing to poor prognosis. Oxaliplatin is one of the most commonly used systemic treatment options for advanced CRC. However, drug resistance - often due to insufficient drug delivery - is still hampering successful treatment. The anticancer activity of oxaliplatin includes besides DNA damage also a strong immunogenic component. Consequently, the aim of this study was to investigate the effect of bacterial ghosts (BGs) as adjuvant immunostimulant on oxaliplatin efficacy. BGs are empty envelopes of gram-negative bacteria with a distinct immune-stimulatory potential. Indeed, we were able to show that the combination of BGs with oxaliplatin treatment had strong synergistic anticancer activity against the CT26 allograft, resulting in prolonged survival and even a complete remission in this murine model of CRC carcinomatosis. This synergistic effect was based on an enhanced induction of immunogenic cell death and activation of an efficient T-cell response leading to long-term anti-tumor memory effects. Taken together, co-application of BGs strengthens the immunogenic component of the oxaliplatin anticancer response and thus represents a promising natural immune-adjuvant to chemotherapy in advanced CRC.

The current status of immunotherapy in peritoneal carcinomatosis

INTRODUCTION

Peritoneal carcinomatosis (PC) is a cancer disease with an urgent need for effective treatment. Conventional chemotherapy failed to show acceptable results. Cytoreductive surgery and hyperthermic chemoperfusion (HIPEC) are only beneficial in few patients with resectable peritoneal metastasis. Immunotherapy could be attractive against PC, as all requirements for immunotherapy are available in the peritoneal cavity.

AREAS COVERED

This review analyzes the present literature for immunotherapy of PC. Advances from immune stimulators, radionucleotide-conjugated- and bispecific antibodies to future developments like adoptive engineered T-cells with chimeric receptors are discussed. The clinical development of catumaxomab, which was the first intraperitoneal immunotherapy to be approved for clinical treatment, is discussed. The requirements for future developments are illustrated. Expert commentary: Immunotherapy of peritoneal carcinomatosis is manageable, showing striking cancer cell killing. Improved profiles of adverse events by therapy-induced cytokine release, enhanced specific killing and optimal treatment schedules within multimodal treatment will be key factors.

A Prebiotic Formula Improves the Gastrointestinal Bacterial Flora in Toddlers

We aimed to investigate the effect of enriched 3-prebiotic formula (including inulin, fructooligosaccharides, and galactooligosaccharides) on toddler gut health by measuring fecal microbiota. Our results revealed that the consumption of 3-prebiotic formula three times per day giving total intake of 1.8 g prebiotic ingredients significantly showed the increased number of probiotic Bifidobacterium spp. colonies and the reduced populations of both C. perfringens and total anaerobic bacteria on the fecal bacterial flora in toddlers at 18~36 months. In addition, total organic acids in the fecal samples significantly increased which improves the utilization of bifidus under acidic conditions after consumption of the 3-prebiotic formula. Therefore, using the formula enriched with prebiotic may maintain gut health in toddlers.

Sodium butyrate and short chain fatty acids in prevention of travellers' diarrhoea: a randomized prospective study

INTRODUCTION

Travellers' diarrhoea (TD) remains a considerable concern among international travellers. Known methods of prevention include dietary precautions, administration of vaccines and antibiotic agents.

AIM

To assess the efficacy of sodium butyrate (SB) and short-chain fatty acids (SCFA) in prevention of TD.

MATERIAL AND METHODS

67 adult patients planning to travel to subtropical countries were originally enrolled in the study. After eliminating 7 patients for not fulfilling the inclusion criteria, 60 patients were randomized into a study group receiving SB with SCFA and a placebo group. Patients were requested to complete previously distributed questionnaire daily. After elimination of 18 patients who did not return questionnaires, 42 patients completed the study (22 study, 20 placebo).

RESULTS

In comparison to the control arm, the study arm noted significantly reduced occurrence of TD (4.5% vs. 40%, p = 0.008), was associated with a significant decrease in number of stools per day in travellers (1.9 vs. 4.2, p = 0.04), as well as a decrease in gastrointestinal symptoms including pain, bloating and nausea with fevers (0.7 vs. 1.4, p = 0.01). We recorded a trend towards decrease in diarrhoea related utilization of medical care in subjects from the study arm. There were no adverse effects noted regarding the use of SB and SCFA.

CONCLUSIONS

Administration of SB with SCFA decreases occurrence of travellers' diarrhoea. It is safe and may constitute a new method of travellers' diarrhoea prevention.

Nitric oxide as a target of complementary and alternative medicines to prevent and treat inflammation and cancer

Nitric oxide (NO) and associated reactive nitrogen species (RNS) are involved in many physiological functions. There has been an ongoing debate to whether RNS can inhibit or perpetuate chronic inflammation and associated carcinogenesis. Although the final outcome depends on the genetic make-up of its target, the surrounding microenvironment, the activity and localization of nitric oxide synthase (NOS) isoforms, and overall levels of NO/RNS, evidence is accumulating that in general, RNS drive inflammation and cancers associated with inflammation. To this end, many complementary and alternative medicines (CAMs) that work in chemoprevention associated with chronic inflammation, are inhibitors of excessive NO observed in inflammatory conditions. Here, we review recent literature outlining a role of NO/RNS in chronic inflammation and cancer, and point toward NO as one of several targets for the success of CAMs in treating chronic inflammation and cancer associated with this inflammation.

Dietary Fiber and the Relationship to Chronic Diseases

Preventative medicine is targeting chronic diseases such as heart disease, cancer, diabetes, and obesity. Populations that consume more dietary fiber have less chronic disease. Intake of dietary fiber has beneficial effects on the risk factors for developing several chronic diseases. Dietary reference intakes recommend the consumption of 14 g of dietary fiber per 1000 kcal, or 25 g for women and 38 g for men, based on the goal of protection against cardiovascular disease. Usual intake of dietary fiber is only 16 g per day. Viscous fibers decrease the glycemic response and may assist in diabetes care. High-fiber diets provide bulk, are more satiating, and have been linked to lower body weights. Evidence that fiber decreases cancer is mixed, and further research is needed. Dietary messages to increase consumption of high-fiber foods such as whole grains, legumes, fruits, and vegetables should be broadly supported by the medical profession. Consumers are also turning to fiber supplements and bulk laxatives as additional fiber sources. As many fiber supplements have not been studied for physiological effectiveness, the best advice is to consume fiber in foods.

Cholesterylbutyrate solid lipid nanoparticles as a butyric acid prodrug

Cholesterylbutyrate (Chol-but) was chosen as a prodrug of butyric acid. Butyrate is not often used in vivo because its half-life is very short and therefore too large amounts of the drug would be necessary for its efficacy. In the last few years butyric acid's anti-inflammatory properties and its inhibitory activity towards histone deacetylases have been widely studied, mainly in vitro. Solid Lipid Nanoparticles (SLNs), whose lipid matrix is Chol-but, were prepared to evaluate the delivery system of Chol-but as a prodrug and to test its efficacy in vitro and in vivo. Chol-but SLNs were prepared using the microemulsion method; their average diameter is on the order of 100-150 nm and their shape is spherical. The antineoplastic effects of Chol-but SLNs were assessed in vitro on different cancer cell lines and in vivo on a rat intracerebral glioma model. The anti-inflammatory activity was evaluated on adhesion of polymorphonuclear cells to vascular endothelial cells. In the review we will present data on Chol-but SLNs in vitro and in vivo experiments, discussing the possible utilisation of nanoparticles for the delivery of prodrugs for neoplastic and chronic inflammatory diseases.

Carbohydrate digestibility and metabolic effects

There is a history of interest in the metabolic effects of alterations in small intestinal digestion and colonic fermentation of carbohydrate. It is believed that the rate of digestion of carbohydrate determines the place and form in which carbohydrate is absorbed. Slowly absorbed or lente carbohydrate sources may reduce postprandial glucose surges and the need for insulin with important implications for lowering coronary heart disease risk and reducing diabetes incidence. Carbohydrates that are not digested in the small intestine will enter the colon, and those that are fermentable will be salvaged as short-chain fatty acids in the colon and at the same time may stimulate colonic microflora, such as bifidobacteria. This process may have metabolic effects in the gut and throughout the host, possibly related to short-chain fatty acid products, although these effects are less well documented. One important aspect of colonic fermentation is the stimulation of certain populations of the colonic microflora, which may assist in the biotransformation of bioactive food components including the cleaving of plant phenolics from their glycone to produce the more rapidly absorbed aglycone. However, human studies have been limited. Therefore, further studies are required to explore these important aspects of metabolism related to the rate of carbohydrate absorption and fermentation and their implications in health and disease.

Colonic health: fermentation and short chain fatty acids

Interest has been recently rekindled in short chain fatty acids (SCFAs) with the emergence of prebiotics and probiotics aimed at improving colonic and systemic health. Dietary carbohydrates, specifically resistant starches and dietary fiber, are substrates for fermentation that produce SCFAs, primarily acetate, propionate, and butyrate, as end products. The rate and amount of SCFA production depends on the species and amounts of microflora present in the colon, the substrate source and gut transit time. SCFAs are readily absorbed. Butyrate is the major energy source for colonocytes. Propionate is largely taken up by the liver. Acetate enters the peripheral circulation to be metabolized by peripheral tissues. Specific SCFA may reduce the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease. Acetate is the principal SCFA in the colon, and after absorption it has been shown to increase cholesterol synthesis. However, propionate, a gluconeogenerator, has been shown to inhibit cholesterol synthesis. Therefore, substrates that can decrease the acetate: propionate ratio may reduce serum lipids and possibly cardiovascular disease risk. Butyrate has been studied for its role in nourishing the colonic mucosa and in the prevention of cancer of the colon, by promoting cell differentiation, cell-cycle arrest and apoptosis of transformed colonocytes; inhibiting the enzyme histone deacetylase and decreasing the transformation of primary to secondary bile acids as a result of colonic acidification. Therefore, a greater increase in SCFA production and potentially a greater delivery of SCFA, specifically butyrate, to the distal colon may result in a protective effect. Butyrate irrigation (enema) has also been suggested in the treatment of colitis. More human studies are now needed, especially, given the diverse nature of carbohydrate substrates and the SCFA patterns resulting from their fermentation. Short-term and long-term human studies are particularly required on SCFAs in relation to markers of cancer risk. These studies will be key to the success of dietary recommendations to maximize colonic disease prevention.

Does butyrate protect from colorectal cancer?

Butyrate, the four-carbon fatty acid, is formed in the human colon by bacterial fermentation of carbohydrates (including dietary fiber), and putatively suppresses colorectal cancer (CRC). Butyrate has diverse and apparently paradoxical effects on cellular proliferation, apoptosis and differentiation that may be either pro-neoplastic or anti-neoplastic, depending upon factors such as the level of exposure, availability of other metabolic substrate and the intracellular milieu. In humans, the relationship between luminal butyrate exposure and CRC has been examined only indirectly in case-control studies, by measuring fecal butyrate concentrations, although this may not accurately reflect effective butyrate exposure during carcinogenesis. Perhaps not surprisingly, results of these investigations have been mutually contradictory. The direct effect of butyrate on tumorigenesis has been assessed in a number of in vivo animal models, which have also yielded conflicting results. In part, this may be explained by methodological differences in the amount and route of butyrate administration, which are likely to significantly influence delivery of butyrate to the distal colon. Nonetheless, there appears to be some evidence that delivery of an adequate amount of butyrate to the appropriate site protects against early tumorigenic events. Future study of the relationship between butyrate and CRC in humans needs to focus on risk stratification and the development of feasible strategies for butyrate delivery.

Evolving anticancer drug valproic acid: insights into the mechanism and clinical studies

The short chain fatty acid valproic acid (VPA) and VPA-analogs modulate the biology of diverse tumor cell entities by inducing differentiation, inhibiting proliferation, increasing apoptosis, and immunogenicity and by decreasing metastatic and angiogenetic potential. This review updates an earlier one in 2002, reflecting the interest in VPA as a potent anticancer drug. A number of in vitro studies show that the types of known tumor cells susceptible to VPA is steadily increasing. Of special note is the strong antineoplastic activity of VPA in chemoresistant cancer cells. A novel and promising approach is combining VPA with other drugs to achieve a broad therapeutic index. Clinical studies are underway and the preliminary results indicate that VPA alone or in combination offers a promising avenue of treatment, both in solid and hematopoetic malignancies.

Apc+/Min colonic epithelial cells express TNF receptors and ICAM-1 when they are co-cultured with large intestine intra-epithelial lymphocytes

Adenomatous polyposis coli (APC) functions are involved in the heterotypic interactions occurring between intestinal epithelial cells (IECs) and intra-epithelial lymphocytes (IELs). These interactions may be of interest in cancer prevention, since recent data provide evidence for lymphocyte mediated immunosurveillance of epithelial cancers. The present study attempts to determine if APC inactivation induces changes in the cross-talk between IEC and large intestine IEL (LI-IEL) through intercellular adhesion molecule (ICAM-1)/leukocyte function-associated (LFA-1) interactions. Mouse Apc+/+ and Apc+/Min colonocytes were co-cultivated with LI-IEL. When co-cultured with LI-IEL Apc+/Min IEC but not Apc+/+ IEC expressed high levels of ICAM-1. The presence of ICAM-1 was linked to TNFalpha production in both co-cultures and TNFR expression only in co-cultivated Apc+/Min IEC. Finally, butyrate enhanced the expression of ICAM-1 in Apc+/Min IEC co-cultured with LI-IEL, and the secretion of TNFalpha by both types of co-cultures. These events could participate in determining the Apc+/Min IEC immunogenicity under different in vivo conditions.

Anti-cancer effects of butyrate: use of micro-array technology to investigate mechanisms

Epidemiological evidence suggests that a high intake of resistant starch and NSP protects against colo-rectal cancer. The mechanisms underlying this protection are thought to be mediated by the short-chain fatty acid butyrate, which is present in the colonic lumen in millimolar concentrations as a result of bacterial fermentation of carbohydrates that have resisted digestion in the small intestine. In vitro studies have shown that butyrate displays a host of chemo-preventative properties including increased apoptosis, reduced proliferation, down regulation of angiogenesis, enhanced immunosurveillance and anti-inflammatory effects in colo-rectal cancer cell lines. However, the molecular mechanisms underlying the apparent chemo-preventative actions of butyrate are largely unknown. The evidence supporting the role of butyrate as an anti-cancer agent is reviewed, with particular emphasis on those studies that have attempted to elucidate the mechanism of action of butyrate. Our understanding of the mechanistic action of butyrate and its role in cancer prevention is likely to advance considerably in this post-genomic era with the application of genomic and proteomic technologies. Studies are described that have used gene array and proteomic techniques to investigate the response of colo-rectal cancer cells to butyrate. These pioneering studies illustrate the potential of these technologies to help characterise the molecular responses of the cancer cell to butyrate, and to define the role of butyrate (and other nutrients) in the prevention of colo-rectal cancer.

Nutritional aspects of short-chain fructooligosaccharides: natural occurrence, chemistry, physiology and health implications

Short-chain fructooligosaccharides occur in a number of edible plants, such as chicory, onions, asparagus, wheat... They are a group of linear fructose oligomers with a degree of polymerisation ranging from n = 1 up to 5 (oligosaccharides). Short-chain fructooligosaccharides, to a large extent, escape digestion in the human upper intestine and reach the colon where they are totally fermented mostly to lactate, short chain fatty acids (acetate, propionate and butyrate), and gas, like dietary fibres. As a consequence of their fermentation, their caloric value is approximately 2 Kcal/g. A faecal bulking effect of fructooligosaccharides has been observed in humans. An important property of short-chain fructooligosaccharides is the stimulation of bifidobacterial growth specifically while suppressing the growth of potentially harmful species such as, for example, Clostridium perfringens in the colon. It is associated with a decrease in faecal pH, an increase in faecal or colonic organic acids, a decrease in the production of nitrogenous end products in urine and stools, a decrease in faecal bacterial enzymatic activities and a modification in faecal neutral sterols. The short-chain fructooligosaccharides enhance magnesium absorption in humans and have been shown, in animal models, to reduce colon tumour development by enhancing both colon butyrate concentrations and local immune system effectors.

Genes modulated by histone acetylation as new effectors of butyrate activity

A wealth of evidence correlates the chemopreventive activity of a fiber-rich diet with the production of butyrate. In order to identify the genes transcriptionally modulated by the molecule, we analyzed the expression profile of butyrate-treated colon cancer cells by means of cDNA expression arrays. Moreover, the effect of trichostatin A, a specific histone deacetylase inhibitor, was studied. A superimposable group of 23 genes out of 588 investigated is modulated by both butyrate and trichostatin A. Among them, a major target was tob-1, a gene involved in the control of cell cycle. tob-1 is also up-regulated by butyrate in a neuroblastoma-derived cell line, and its overexpression in the colon cells caused growth arrest. Our findings represent an extensive analysis of genes modulated by butyrate and identify completely new effectors of its biological activities.

Dietary sugar beet fiber prevents the increase in aberrant crypt foci induced by gamma-irradiation in the colorectum of rats treated with an immunosuppressant

We demonstrated recently that gamma-irradiation can induce aberrant crypt foci (ACF) in the rat colorectum. The aim of this study was to evaluate the effect of dietary sugar beet fiber (SBF) on the distribution of the CD8(+) intraepithelial lymphocyte (IEL) in the colorectum and on the number of gamma-irradiation-induced ACF of rats administered anti-asialo GM1 (alpha AGM1) as an immunosuppressant. Wistar/ST rats fed a fiber-free diet or the diet supplemented with SBF (100 g/kg diet) were administrated alpha AGM1 or normal rabbit serum as a control during the initiation period with gamma-irradiation. At 5 and 9 wk after the first irradiation, ACF and total aberrant crypts (AC) per area in the colorectum were counted. The numbers of ACF (P = 0.0010) and AC (P = 0.0635) per unit area were lower in the SBF-fed group than in the rats fed the fiber-free diet. alpha AGM1 administration significantly raised the number of ACF (P = 0.0001) and AC (P = 0.0006) per area in the colorectum. Moreover, alpha AGM1 administration during the initiation period reduced the number of CD8(+) IEL per 100 cells in the epithelial layer (P = 0.0001) of the colon. These results demonstrate that reduction of the number of CD8(+) IEL per 100 cells in the epithelial layer as a result of alpha AGM1 administration promotes the formation of irradiation-induced ACF in the colorectum. The number of CD8(+) IEL per 100 cells in epithelial layer was lower in the group fed the fiber-free diet than in the SBF-fed group (P = 0.0522). These results indicated that the ingestion of dietary SBF suppressed gamma-irradiation-induced ACF formation through the immune surveillance in the colorectal mucosa.

Kill and cure: dietary augmentation of immune defences against colon cancer

At its most fundamental, cancer is a genetic disease resulting from inherited or acquired mutations in tumour suppressor genes and proto-oncogenes. Environmental factors, including ingested food components, interact with genetic inheritance to determine individual cancer risk. There is growing evidence that the immune system exerts selective pressure during neoplastic development. Tumour cells that evade this immunosurveillance because they are non-antigenic or because they defend themselves successfully against immune attack have a survival advantage. Effective chemopreventative agents will include dietary components that enhance the immune system's ability to identify transformed cells and to target them for apoptosis.

Feasibility of therapeutic pneumoperitoneum in a large animal model using a microvaporisator

BACKGROUND

Multimodal therapy is used increasingly in advanced gastrointestinal tumors. Potential benefits of using an intraoperative adjuvant therapy during laparoscopy for cancer have been documented in animal studies. The aim of this study was to develop a device that could deliver such an intraoperative drug therapy.

METHODS

We developed a micropump suitable for minimally invasive surgery procedures that allowed microdroplets of therapeutic substance to be distributed into the pneumoperitoneum (CO2), creating a "therapeutic pneumoperitoneum." A closed-loop control system regulates drug delivery according to the gas flow. In vitro, the micropump is able to aerosolize various aqueous and ethanol solutions, including cytostatic and bacteriostatic drugs and adhesion-modulating agents. The size of the microdroplets has been optimized to prevent visual artifacts.

RESULTS

The micropump was tested in an animal model (pig). The system was inserted into a 5-mm trocar. After insufflation of a 12-mm CO2 pneumoperitoneum, laparoscopic sigmoid colon resections could be performed with no special difficulties. No fog developed, and no system-related complication was observed. At autopsy, the active principle was distributed to all exposed peritoneal surfaces.

CONCLUSIONS

As opposed to conventional peritoneal washing, therapeutic pneumoperitoneum reaches the entire peritoneal surface, allowing an optimal drug distribution. Drug diffusion into the tissues is enhanced by the intraperitoneal pressure. Precise determination of the instantaneous and total drug quantity is possible. Therefore, this drug delivery system has several advantages over conventional irrigation. Its potential domains of application are locoregional cancer therapy, prevention of port-site recurrences, immunomodulation, analgesia, peritonitis, and prevention of postoperative adhesions.

T cell status influences colon tumor occurrence in min mice fed short chain fructo-oligosaccharides as a diet supplement

We have previously shown that addition of short chain fructo-oligosaccharides (indigestible carbohydrates) to food prevented colon tumors in C57BL/6-Apc(Min/+) mice, a model for human colon cancer. As gut-associated lymphoid tissue was concomitantly developed, we suggested that the immune response generated by this food may interfere with carcinogenesis due to involvement of mucosal cells in the regulation of tissue homeostasis. In the present experiment, we tested whether T cell status may influence colon tumor formation in Min mice fed a food supplement of short chain fructo-oligosaccharides. Min mice depleted of CD4(+) and CD8(+) lymphocytes developed twice as many tumors as immunocompetent mice (0.8 as compared with 0.4, the mean number in 7-week-old Min mice when food supplementation began; P = 0.02). It is concluded that food supplementation with a substrate (a known prebiotic) fermented in the colon may stimulate a mechanism of immunosurveillance that would otherwise remain inefficient.

Production and characterisation of a monoclonal antibody specific for apoptotic bodies derived from several tumour cell lines

We have recently shown that apoptotic bodies (apobodies) derived from rat colon carcinoma cell lines (PROb) after sodium butyrate (NaB) treatment were able to cure rats with induced peritoneal carcinomatosis ( [BOISTEAU] ). A specific immune response was assumed to be involved since the serum of cured rats contained antibodies specific for apobodies. In the present study, a mAb (clone 6E8) produced by immunisation of rats with apobodies strongly recognized apobodies but had little reactivity with parental tumour cell lines, as demonstrated by enzyme-linked immunosorbent assay (ELISA), immunostaining and flow cytometry. Immunoelectron microscopy showed that 6E8 mAb mainly stained the hyaloplasm or cytosol of apobodies. A protein was detected at 67 kDa by immunoprecipitation of apobodies with mAb, followed by immunoblotting, using serum of rats immunised with apobodies. The 6E8 mAb recognized apobodies derived from several rat or human colon cancer cell lines and a rat glioma cell line, regardless of the apoptosis stimulus used (NaB, staurosporine or UV). Our results clearly show that 6E8 mAb defines an epitope specifically generated during apoptosis, which suggests that the protein recognized may be involved in the molecular cascade of apoptotic cell death.

Inhibitory effect of microfibril wheat bran on azoxymethane-induced colon carcinogenesis in CF1 mice

Microfibril wheat bran (MFW), a processed dietary fiber prepared by milling of coarse wheat bran (WB), is softer and has a more pleasant taste than WB. In this study, we examined the inhibitory effect of MFW on azoxymethane (AOM)-induced colon carcinogenesis in female CF1 mice and compared its effect with that of WB and cellulose (CL). The mice were fed a modified AIN 76 A diet supplemented with either MFW, WB, or CL at a final concentration of 20% (w/w). Six weekly s.c. injections of AOM (10 mg/kg body weight) were administered per mouse commencing 1 week after the start of the feeding period. Control mice were injected with saline only. Thirty-three weeks after the initial injection, the mice were sacrificed, examined for tumors, and the cecal contents were analyzed to determine the moisture content and the concentrations of short-chain fatty acids (SCFA). The average number of total tumors per mouse in the MFW (2.9 +/- 0.6, P = 0.017) and WB (5.3 +/- 1.3, P = 0.373) diet groups was lower than that of the CL diet group (7.5 +/- 1.3), though there was no significant difference in tumor incidence (94.7%, 90.0% and 94.7%, respectively) between the groups. More than 90% of the tumors in each group were adenocarcinomas. The incidence of adenoma and that of carcinoma in situ in the MFW diet group (5.3% and 0%, respectively) were also lower than those in the CL diet group (26.3 and 26.3%, respectively; P = 0.180 and P = 0.046, respectively). Analysis of the cecal contents revealed a significantly higher moisture content and significantly higher concentrations of SCFA, butyrate in particular, in the MFW and WB diet groups. The results of this study indicate that the source and texture of dietary fiber can influence tumor development in CF1 mice, and more specifically that MFW is a promising and useful dietary supplement with properties serving to protect against the development of colon cancer.

Conjugated linoleic acid and other anticarcinogenic agents of bovine milk fat

Prevention is an important strategy for conquering cancer. Milk fat contains a number of components, such as conjugated linoleic acid, sphingomyelin, butyric acid, ether lipids, beta-carotene, and vitamins A and D that have anticancer potential. Conjugated linoleic acid inhibits the growth of a number of human cancer cell lines and suppresses chemically-induced tumor development at a number of sites in animal models. As little as 0.1% of dietary conjugated linoleic acid inhibits the development of rat mammary tumors, independent of the amount and type of fat in the diet. Sphingomyelin, through its metabolites ceramide and sphingosine, participates in multiple antiproliferative pathways associated with suppression of carcinogenesis. Dietary sphingomyelin inhibits murine colon tumor development. Butyric acid, uniquely present in ruminant milk, is a potent antineoplastic agent and may ameliorate its potency through synergy with other milk fat components. Dietary butyric acid inhibits mammary carcinoma development in rats. In humans, ether lipids, beta-carotene, and vitamins A and D are associated with anticancer effects. Cows have the ability to extract anticarcinogenic components from pasture and feed and transfer them to milk. Use of genetic engineering and other techniques to increase the range and level of anticarcinogens in pasture and supplements may increase the anticancer potential of milk.

Interleukin-2/sodium butyrate treatment cures rats bearing liver tumors after acquired 5-fluorouracil resistance

We studied the effect of immunotherapy using recombinant interleukin-2 (rIL-2) in combination with a differentiating agent, sodium butyrate (NaBut), on experimental 5-fluorouracil (5-FU)-resistant liver metastasis from colorectal cancer in rats. For this purpose, we used direct liver injection of 5-FU resistant cells, PRObRI, in syngeneic BDIX rats to establish liver tumors. The growth of liver metastasis was followed before and after NaBut/rIL-2 treatment by magnetic resonance imaging (MRI). The presence of liver tumors was checked by MRI 7 days after tumor cell injection. Evaluable rats were then assigned randomly to a control and an experimental group. The different treatments were started on day 10 and administered intraperitoneally (i.p.). Combined NaBut/rIL-2 treatment followed by MRI on days 56 and 91 was shown both to significantly reduce the growth of liver tumors and to prevent extrahepatic spread. In addition, NaBut/rIL-2 treatment induced a complete regression in 50% of the rats which remained free of disease.

Role of butyric acid and its derivatives in the treatment of colorectal cancer and hemoglobinopathies

Butyric acid, a short chain fatty acid (SCFA), is a natural component of the animal metabolism. Physiological concentrations induce multiple and reversible biological effects. They concern regulatory mechanisms of gene expression conducing to promote markers of cell differentiation, apoptosis and cell growth control. The described hyperacetylation of histones and the induction of several immune or non-immune cell-activating mediators are consistent with the pleiotropic stimulatory effect of the agent. Butyric acid is considered as a biological response modifier (BRM) and is an interesting tool for biological studies. The history of butyric acid as a putative medication in human health is spanning since 60 years and is confusing in part because of conflicting data between exciting experimental results and clinical trials. In light of minimal impact of systemic therapy and the short half-life of the saline molecule used, it is evident that continuous infusions of butyrate are required to improve the efficacy of the treatment. Butyric acid has been viewed with skepticism because of less convenient for long-term chronic therapy. New experimental data from several studies conduced within the past decade with butyric derivatives, delivery systems, and long-acting prodrugs, have demonstrated the practical value of the therapeutic concept. To support issues regarding clinical development, it was of interest to evaluate the recent information, showing butyric acid currently considered as therapeutic purposes in the treatment of colorectal cancer and hemoglobinopathies.

Induction of antigen presentation by macrophages after phagocytosis of tumour apoptotic cells

Due to their resistance to classical chemotherapies, most human colorectal cancers have a high incidence and a poor prognosis. Immunotherapy using interleukin 2 (IL2) has provided disappointing results in the treatment of these cancers. Recently, however, we have demonstrated that a treatment combining a cell-differentiating agent, sodium butyrate (NaBut) with IL2 resulted in a remission of established peritoneal colorectal carcinomatosis in rats. Separately, neither NaBut nor IL2 treatment cured these tumour-bearing rats. NaBut is known to induce cell differentiation and subsequent apoptosis in epithelial cells, while IL2 stimulates the immune cells capable of participating in tumour rejection. We postulated that the significant therapeutic effect of NaBut/IL2 treatment could be attributed to a NaBut-induced increase in the immunogenicity of the cancer cells. We report here that NaBut induced an apoptotic process in rat colon tumour cells in vivo and in vitro. We observed, in an efficient cure, colocalization of apoptotic bodies and monocytes/macrophages at the periphery of the tumour. We propose that these apoptotic bodies are phagocytosed in vivo by the macrophages. We also showed in vitro that a subpopulation of macrophages involved in the phagocytic clearance of apoptotic cells expresses cell surface molecules associated with antigen presentation and stimulates the proliferation of naive splenocytes. Our data suggest that therapies that recruit massive induction of the apoptotic process in tumour cells could favour tumour antigen presentation via their specific phagocytosis by antigen-presenting cells (APCs). We propose that the development of specific therapies that stimulate both tumour cell apoptosis and the immune system could offer new opportunities in anti-cancer treatments of poorly immunogenic cancer cells.

Suppression of the number of aberrant crypt foci of rat colorectum by ingestion of sugar beet fiber regardless of administration of anti-asialo GM1

Anti-asialo GM1 serum (AGM1) reduces natural killer (NK) activity in vitro and in vivo. We investigated the effect of ingestion of sugar beet fiber (SBF) on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) and whether the effect was maintained under NK-reducing conditions by AGM1 injection. The ingestion of SBF decreased the number of ACF in the colorectum at 4 weeks after treatment with DMH. Dietary SBF had a suppressive effect on the formation of ACF regardless of the administration of AGM1. These results suggest that the suppressive effect created by the ingestion of SBF may overwhelm the effect of AGM1 treatment on ACF formation.

5-Fluorouracil-resistant colonic tumors are highly responsive to sodium butyrate/interleukin-2 bitherapy in rats

Advanced colorectal cancer is generally refractory to 5-fluorouracil (5-FU) chemotherapy. This is linked to the emergence of resistant cell populations, probably due to a selection process. The identification of molecular markers and the improvement of alternative therapies thus remain important. We have used as an experimental model a rat colon cancer cell line (PROb), which exhibits features similar to those of the human situation. 5-FU treatment of rats bearing PROb tumors enhanced their survival but did not lead to cure. A PROb 5-FU-resistant subline (PRObR1) was obtained by continuous in vitro exposure to 5-FU. Resistance to 5-FU was accompanied by a 2-fold increase in thymidylate synthase activity and a substantially higher incorporation of thymidine in the presence of 5-FU, compared with parental PROb cells. Unexpectedly, in syngeneic rats, PRObR1 tumors exhibited delayed growth when compared with parental PROb tumors. This was ascribed to an increased sensitivity of PRObR1 cells to host immune response since no growth delay was observed in immunocompromised nude mice and since there was no detectable difference in proliferation rates between PROb and PRObR1 cells. 5-FU treatment was inefficient in prolonging the survival of rats bearing PRObR1 tumors. In contrast, an immunotherapeutic protocol combining sodium butyrate and recombinant interleukin-2 (NaBut/rIL-2) cured 80% of the rats bearing established PRObR1 tumors. Our results suggest that NaBut/rIL-2 treatment is efficient against 5-FU-chemoresistant rat colon cancer.

Overexpression of adenovirus-encoded transgenes from the cytomegalovirus immediate early promoter in irradiated tumor cells

Efficient expression of therapeutic genes in irradiated tumor cells would facilitate the conversion of a malignant tumor nodule into a cancer vaccine in situ. We reported previously that transgene expression from an adenoviral vector could be markedly enhanced by treating transduced tumor cells with butyrate. In this study, we demonstrated that a similar butyrate effect could be achieved in irradiated tumor cells. In addition, irradiating cells at doses of 2-40 Gy prior to transduction could also amplify recombinant adenoviral transgene products in a cell-type-specific manner. This suggests that adenovirus-mediated gene therapy, radiation therapy, and butyrate-mediated cancer therapy may potentially be formulated into one synergistic protocol for cancer treatment.

Interleukin-2-activated killer cell activity in colorectal tumor patients: evaluation of in vitro effects by prothymosin alpha1

The effects of prothymosin alpha1 (Pro alpha1) in combination with interleukin-2 (IL-2) on peripheral blood lymphocytes from 50 colorectal tumor patients at different stages were studied with respect to immunocytotoxicity, adhesion to cultured SW620 colon carcinoma cells, secretion of cytokines and expression of adhesion and surface marker molecules. On average, the patients showed lower natural killer (NK) cell activity than healthy donors, which was associated with a lower adhesion capacity to the tumor target cells. The NK cell activity of the patients was inversely related to the tumor stage. The generation of lymphokine(IL-2)-activated killer (LAK) cell activity was found to be comparable on lymphocytes from healthy individuals and patients and was not correlated to tumor stage. Pro alpha1 stimulated patients' LAK cell activity only, primarily at the early stage (Dukes A/B). The Pro alpha1 effect was associated with an increased adhesion of lymphocytes to tumor target cells and an increased secretion of the deficient IL-2-induced IFN gamma secretion. No significant effects on the low level of TNF alpha secretion was noted. By flow cytometry, Pro alpha1 in combination with IL-2 augmented the expression of the NK cell markers CD56, CD16/56, the subset CD3/16/56 and CD25 on lymphocytes of the patients. In contrast, Pro alpha1 was equally effective by increasing the expression of CD18 and CD11a on lymphocytes from the patients and from normal controls. In conclusion, Pro alpha1, in combination with IL-2, can partially normalize lymphocyte deficiencies of colon cancer patients in vitro. This potential might provide an experimental basis for applying Pro alpha1 or related thymic peptides in selected immunotherapies against colorectal tumors.

Butyrate inhibits seeding and growth of colorectal metastases to the liver in mice

BACKGROUND

The short-chain fatty acid butyrate inhibits growth of colorectal carcinoma cells in vitro. Mevalonate, a short-chain fatty acid structurally and metabolically related to butyrate, is important in signal transduction and is essential for cell growth. We investigated butyrate's effects on seeding and growth of colorectal tumor cells metastatic to the liver in vivo and hypothesized that butyrate's antiproliferative effects are associated with inhibition of mevalonate-mediated cell growth.

METHODS

Hepatic metastases were induced by injecting 1 x 10(5) MC-26 (N-methyl-N-nitrosourea-induced murine colorectal carcinoma) cells into the spleen of BALB/c mice. Mice were treated with a continuous intravenous infusion of butyrate (2 gm/kg/day) for 7 days starting 24 hours before tumor cells were injected. Study variables included liver weight and number of hepatic surface metastases. Proliferation studies on MC-26 cells were performed in vitro to examine the effects of butyrate alone or combined with mevalonate or mevastatin (an inhibitor of mevalonate synthesis).

RESULTS

Butyrate reduced seeding and growth of colorectal tumor cells in vivo. Mevalonate diminished butyrate's antiproliferative action in vitro, whereas mevastatin potentiated this effect.

CONCLUSIONS

These studies (1) show that butyrate inhibits seeding and growth of hepatic colorectal metastases in vivo, (2) associate butyrate's antiproliferative effects with inhibition of mevalonate-mediated cell growth, and (3) indicate that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors may have synergistic antiproliferative effects when combined with butyrate.

Immunization against a rat colon carcinoma by sodium butyrate-treated cells but not by interleukin 2-secreting cells

BACKGROUND & AIMS

Vaccination of patients with colon cancer with irradiated autologous tumor cells and bacille Calmette-Guérin (BCG) was reported to augment mean survival. It was recently observed that a local treatment combining recombinant interleukin 2 and the differentiation agent sodium butyrate cured rats with colon cancer peritoneal carcinomatosis. To optimize vaccination protocols, the comparison of the efficacy of irradiated tumor cells mixed with BCG with that of interleukin 2-gene-transfected cells and of tumor cells pretreated with sodium butyrate was performed.

METHODS

The poorly immunogenic rat colon carcinoma cells PROb were used in a vaccination assay. Interleukin 2-transfected PROb cells, either proliferating or irradiated, were used. The efficiency of irradiated PROb cells mixed with BCG, of interleukin 2-transfected cells, or of cells pretreated with sodium butyrate was tested.

RESULTS

Vaccination with irradiated parental cells and BCG did not provide protection. Irradiated interleukin 2-transfected cells were poorly efficient in the vaccination assay. Conversely, vaccination with irradiated parental cells pretreated with sodium butyrate before injection provided good protection.

CONCLUSIONS

Interleukin 2-secreting cells efficiently vaccinated animals when injected while replicating but not after irradiation. Conversely, sodium butyrate pretreatment provided a simple and efficient vaccination scheme that generated a long-term immune memory and allowed the use of irradiated cells.

Role of short-chain fatty acids in the prevention of colorectal cancer

Short-chain fatty acids (SCFAs: acetate, propionate, n-butyrate) arising in the large bowel during bacterial fermentation of dietary fibre and starch have paradoxical effects on colonic epithelial proliferation. While the three major SCFAs stimulate proliferation of normal crypt cells, n-butyrate and, to a lesser degree, propionate inhibit growth of colon cancer cell lines. At the molecular level, n-butyrate causes histone acetylation, favours differentiation, induces apoptosis and regulates the expression of various oncogenes. To understand the complex effects of SCFAs on carcinogenesis, it is important to study the intermediate stages of the adenoma-carcinoma sequence where a "switch" from stimulation to suppression of cell proliferation must occur.