The chemopreventive activity of the histone deacetylase inhibitor tributyrin in colon carcinogenesis involves the induction of apoptosis and reduction of DNA damage

Ripe papaya pectins inhibit the proliferation of colon cancer spheroids and the formation of chemically induced aberrant crypts in rats colons

Pectins are a class of soluble polysaccharides that can have anticancer properties through several mechanisms. This study aimed to characterize the molecular structure of water-soluble fractions (WSF) derived from ripe and unripe papayas and assess their biological effects in two models: the 3D colon cancer spheroids to measure cell viability and cytotoxicity, and the in vivo model to investigate the inhibition of preneoplastic lesions in rats. WSF yield was slightly higher in ripe papaya, and both samples mainly consisted of pectin. Both pectins inhibited the growth of colon cancer HT29 and HCT116 spheroids. Unripe pectin disturbed HT29/NIH3T3 spheroid formation, decreased HCT116 spheroid viability, and increased spheroid cytotoxicity. Ripe pectin had a more substantial effect on the reduction of spheroid viability for HT29 spheroids. Furthermore, in vivo experiments on a rat model revealed a decrease in aberrant crypt foci (ACF) formation for both pectins and increased apoptosis in colonocytes for ripe papaya pectins. The results suggest potential anticancer properties of papaya pectin, with ripe pectin showing a higher potency.

Exploring the gut microbiota and its potential as a biomarker in gliomas

Gut microbiome alterations are associated with various cancers including brain tumours such as glioma and glioblastoma. The gut communicates with the brain via a bidirectional pathway known as the gut-brain axis (GBA) which is essential for maintaining homeostasis. The gut microbiota produces many metabolites including short chain fatty acids (SCFAs) and essential amino acids such as glutamate, glutamine, arginine and tryptophan. Through the modulation of these metabolites the gut microbiome is able to regulate several functions of brain cells, immune cells and tumour cells including DNA methylation, mitochondrial function, the aryl hydrocarbon receptor (AhR), T-cell proliferation, autophagy and even apoptosis. Here, we summarise current findings on gut microbiome with respect to brain cancers, an area of research that is widely overlooked. Several studies investigated the relationship between gut microbiota and brain tumours. However, it remains unclear whether the gut microbiome variation is a cause or product of cancer. Subsequently, a biomarker panel was constructed for use as a predictive, prognostic and diagnostic tool with respect to multiple cancers including glioma and glioblastoma multiforme (GBM). This review further presents the intratumoural microbiome, a fascinating microenvironment within the tumour as a possible treatment target that can be manipulated to maximise effectiveness of treatment via personalised therapy. Studies utilising the microbiome as a biomarker and therapeutic strategy are necessary to accurately assess the effectiveness of the gut microbiome as a clinical tool with respect to brain cancers.

The Role of Gut Microbiome-Derived Short-Chain Fatty Acid Butyrate in Hepatobiliary Diseases

The short-chain fatty acid butyrate, produced from fermentable carbohydrates by gut microbiota in the colon, has multiple beneficial effects on human health. At the intestinal level, butyrate regulates metabolism, helps in the transepithelial transport of fluids, inhibits inflammation, and induces the epithelial defense barrier. The liver receives a large amount of short-chain fatty acids via the blood flowing from the gut via the portal vein. Butyrate helps prevent nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, inflammation, cancer, and liver injuries. It ameliorates metabolic diseases, including insulin resistance and obesity, and plays a direct role in preventing fatty liver diseases. Butyrate has different mechanisms of action, including strong regulatory effects on the expression of many genes by inhibiting the histone deacetylases and modulating cellular metabolism. The present review highlights the wide range of beneficial therapeutic and unfavorable adverse effects of butyrate, with a high potential for clinically important uses in several liver diseases.

Butyrate-containing structured lipids act on HDAC4, HDAC6, DNA damage and telomerase activity during promotion of experimental hepatocarcinogenesis

Hepatocellular carcinoma (HCC) presents with a high treatment resistance and poor prognosis. Early diagnosis and preventive approaches such as chemoprevention are essential for the HCC control. Therefore, we evaluated the chemopreventive effects of butyrate-containing structured lipids (STLs) administered during the promotion stage of hepatocarcinogenesis in rats submitted to the 'resistant hepatocyte' (RH) model. Administration of butyrate-containing STLs inhibited the incidence and mean number of visible hepatic nodules per rat and reduced the number and area of glutathione S-transferase placental form-positive (GST-P+) preneoplastic focal lesions in the livers. This was accompanied by the induction of apoptosis and an increased level of hepatic butyric acid. Treatment with butyrate-containing STLs resulted in increased histone H3 lysine 9 (H3K9) acetylation, reduction of total histone deacetylase (HDAC) activity, and lower levels of HDAC4 and HDAC6 proteins. The chemopreventive effect of butyrate-containing STLs was also associated with the increased nuclear compartmentalization of p53 protein and reduced expression of the Bcl-2 protein. In addition, rats treated with butyrate-containing STLs showed decreased DNA damage and telomerase activity in the livers. These results demonstrate that the suppressive activity of butyrate-containing STLs is associated with inhibition of elevated during hepatocarcinogenesis chromatin-modifying proteins HDAC4 and HDAC6, subcellular redistribution of the p53 protein, and decreased DNA damage and telomerase activity.

An efficient system for intestinal on-site butyrate production using novel microbiome-derived esterases

Short-chain fatty acids, especially butyrate, play beneficial roles in sustaining gastrointestinal health. However, due to limitations associated with direct consumption of butyrate, there has been interest in using prodrugs of butyrate. Tributyrin (TB), a triglyceride composed of three butyrate molecules and a glycerol, is a well-studied precursor of butyrate. We screened a metagenome library consisting of 5760 bacterial artificial chromosome clones, with DNA inserts originating from mouse microbiomes, and identified two clones that efficiently hydrolyse TB into butyrate. Nucleotide sequence analysis indicated that inserts in these two clones are derived from unknown microbes. BLASTp analysis, however, revealed that each insert contains a gene homologous to acetylesterase or esterase genes, from Clostridium spp. and Bacteroides spp., respectively. Predicted structures of these two proteins both contain serine-histidine-aspartate catalytic triad, highly conserved in the family of esterases. Escherichia coli host expressing each of the two candidate genes invariably produced greater amounts of butyrate in the presence of TB. Importantly, administration of TB together with cloned E. coli cells alleviated inflammatory symptoms in a mouse model of acute colitis. Based on these results, we established an efficient on-site and real-time butyrate production system that releases butyrate in a controlled manner inside the intestine.

Death by histone deacetylase inhibitor quisinostat in tongue squamous cell carcinoma via apoptosis, pyroptosis, and ferroptosis

Tongue cancer is one of the most common oral malignancies. Quisinostat is a histone deacetylase inhibitor with antitumor activity. The aim of this study was to evaluate the effects of quisinostat on the viability of tongue squamous cell carcinoma (TSCC) cells (CAL-27, TCA-8113) in vitro and in vivo. Cell viability, cell morphological observation, scratch wound-healing assay, transwell migration assay, transmission electron microscope, flow cytometry and cellular reactive oxygen species were assessed in vitro. The results showed that quisinostat can significantly inhibit the viability, growth and migration of TSCC cells. And quisinostat could significantly induce TSCC cells apoptosis, pyroptosis, and ferroptosis. Quisinostat significantly inhibited tumor tissue growth in animal experiments. Up-regulation of the expression of Bax, cleaved-caspase3, caspase-1, p53, phospho-p53 and down-regulated of the expression of caspase-3, Bcl-2, GPX4 in cell lines and tumor tissues of nude mice were observed by Western blotting analysis. Up-regulation of the expression of caspase-1, Bax, cleaved-caspase3, p53 and down-regulated of the expression of ki67, caspase-3, Bcl-2, GPX4 in tumor tissues of nude mice were observed by immunohistochemistry. TUNEL analysis showed that quisinostat could increase the apoptosis rate in the tumor tissues of nude mice. Up-regulation of the expression of p53 and down-regulated expression of GPX4 in cell lines were observed by immunofluorescent staining, and the expression locations of p53 and GPX4 proteins in TSCC cells were observed. Based on these findings, quisinostat may be a potential drug for the treatment of tongue squamous cell carcinoma.

Antiangiogenic effects of the chemopreventive agent tributyrin, a butyric acid prodrug, during the promotion phase of hepatocarcinogenesis

Agents that inhibit angiogenic factors may prevent the development of hepatocellular carcinoma (HCC). Thus, the objective of this study was to kinetically evaluate the antiangiogenic activity of tributyrin (TB), a butyric acid prodrug, in the promotion stage of hepatocarcinogenesis. For this purpose, the resistant hepatocyte (RH) model was used for induction of preneoplastic lesions in Wistar rats. During the promotion phase, the animals received TB or maltodextrin (MD) as control daily. The rats were killed at three time-points (P1, P2 and P3). Increased expression of Vegfa and Vegfr2 was observed during promotion phase of hepatocarcinogenesis, which was not reversed by TB treatment. However, TB treatment reduced the expression of cluster of differentiation (CD) 34-positive vessels at P3 and α-smooth muscle actin (α-SMA)-positive vessels at P2 compared with MD. Enhanced levels of hypoxia inducible factor-1α (HIF-1α) and phosphorylated extracellular signal-regulated kinases (pERK) were detected at P3 when compared with P1 and P2 in the MD treatment. TB treatment reduced the levels of HIF-1α and pERK at P3 relative to the MD control. Experiments with human umbilical vein endothelial cells (HUVEC) showed that sodium butyrate (NaBu) inhibited cell migration and tube formation, confirming the antiangiogenic activity of its prodrug TB. In conclusion, antiangiogenic activity of TB is an early event that already occurs in preneoplastic livers, reinforcing its potential chemopreventive effects against HCC.

Effect of Short Chain Fatty Acids on Age-Related Disorders

Recent studies have indicated a prominent role of intestinal microbiota in regulation of several physiological aspects of the host including development and activation of the immune system and control of metabolism. In this review, we focused our discussion on bacterial metabolites produced from dietary fiber fermentation called short-chain fatty acids, which act as a link between the microbiota and host cells. Specifically, we described how modifications in their intestinal levels are associated with development of age-related pathologies including metabolic diseases and type 2 diabetes, hypertension, cardiovascular and neurodegenerative diseases. We also highlight their impact on the development of cancer.

Tributyrin Inhibits Ethanol-Induced Epigenetic Repression of CPT-1A and Attenuates Hepatic Steatosis and Injury

Ethanol-mediated down-regulation of carnitine palmitoyltransferase-1 (CPT-1A) gene expression plays a major role in the development of hepatic steatosis; however, the underlying mechanisms are not completely elucidated. Tributyrin, a butyrate prodrug that can inhibit histone deacetylase (HDAC) activity, attenuates hepatic steatosis and injury. The present study examined the beneficial effect of tributyrin/butyrate in attenuating ethanol-induced pathogenic epigenetic mechanisms affecting CPT-1A promoter-histone modifications and gene expression and hepatic steatosis/injury.

METHODS

Mice were fed a liquid Lieber-DeCarli diet (Research Diet Inc, New Brunswick, NJ) with or without ethanol for 4 weeks. In a subset of mice, tributyrin (2 g/kg) was administered orally by gavage. Primary rat hepatocytes were treated with 50 mmol/L ethanol and/or 2 mmol/L butyrate. Gene expression and epigenetic modifications at the CPT-1A promoter were analyzed by chromatin immunoprecipitation analysis.

RESULTS

In vivo, ethanol induced hepatic CPT-1A promoter histone H3K9 deacetylation, which is indicative of a repressive chromatin state, and decreased CPT-1A gene expression. Our data identified HDAC1 as the predominant HDAC causing CPT-1A promoter histone H3K9 deacetylation and epigenetic down-regulation of gene expression. Significantly, Specificity Protein 1 (SP1) and Hepatocyte Nuclear Factor 4 Alpha (HNF4α) participated in the recruitment of HDAC1 to the proximal and distal regions of CPT-1A promoter, respectively, and mediated transcriptional repression. Importantly, butyrate, a dietary HDAC inhibitor, attenuated ethanol-induced recruitment of HDAC1 and facilitated p300-HAT binding by enabling SP1/p300 interaction at the proximal region and HNF4α/peroxisomal proliferator-activated receptor-γ coactivator-1α/p300 interactions at the distal region, leading to promoter histone acetylation and enhanced CPT-1A transcription.

CONCLUSIONS

This study identifies HDAC1-mediated repressive epigenetic mechanisms that underlie an ethanol-mediated decrease in CPT-1A expression. Importantly, tributyrin/butyrate inhibits HDAC1, rescues CPT-1A expression, and attenuates ethanol-mediated hepatic steatosis and injury, suggesting its potential use in therapeutic strategies for alcoholic liver disease.

Milk fat components with potential anticancer activity-a review

During many years, the milk fat has been unfairly undervalued due to its association with higher levels of cardiovascular diseases, dyslipidaemia or obesity, among others. However, currently, this relationship is being re-evaluated because some of the dairy lipid components have been attributed potential health benefits. Due to this, and based on the increasing incidence of cancer in our society, this review work aims to discuss the state of the art concerning scientific evidence of milk lipid components and reported anticancer properties. Results from the in vitro and in vivo experiments suggest that specific fatty acids (FA) (as butyric acid and conjugated linoleic acid (CLA), among others), phospholipids and sphingolipids from milk globule membrane are potential anticarcinogenic agents. However, their mechanism of action remains still unclear due to limited and inconsistent findings in human studies.

Role of short-chain fatty acids in colonic inflammation, carcinogenesis, and mucosal protection and healing

Short-chain fatty acids (SCFAs), mainly acetate, propionate, and butyrate, produced by microbial fermentation of undigested food substances are believed to play a beneficial role in human gut health. Short-chain fatty acids influence colonic health through various mechanisms. In vitro and ex vivo studies show that SCFAs have anti-inflammatory and anticarcinogenic effects, play an important role in maintaining metabolic homeostasis in colonocytes, and protect colonocytes from external harm. Animal studies have found substantial positive effects of SCFAs or dietary fiber on colonic disease, but convincing evidence in humans is lacking. Most human intervention trials have been conducted in the context of inflammatory bowel disease. Only a limited number of those trials are of high quality, showing little or no favorable effect of SCFA treatment over placebo. Opportunities for future research include exploring the use of combination therapies with anti-inflammatory drugs, prebiotics, or probiotics; the use of prodrugs in the setting of carcinogenesis; or the direct application of SCFAs to improve mucosal healing after colonic surgery.

Effects of monobutyrin and tributyrin on liver lipid profile, caecal microbiota composition and SCFA in high-fat diet-fed rats

Butyric acid has been shown to have suppressive effects on inflammation and diseases related to the intestinal tract. The aim of the present study was to investigate whether supplementation of two glycerol esters, monobutyrin (MB) and tributyrin (TB), would reach the hindgut of rats, thus having an effect on the caecal profile of SCFA, microbiota composition and some risk markers associated with chronic inflammation. For this purpose, rats were fed high-fat diets after adding MB (1 and 5 g/kg) and TB (5 g/kg) to a diet without any supplementation (high-fat control; HFC). A low-fat (LF) diet was also included. In the liver, total cholesterol concentrations, LDL-cholesterol concentrations, LDL:HDL ratio, and succinic acid concentrations were reduced in rats given the MB and TB (5 g/kg) diets, compared with the group fed the HFC diet. These effects were more pronounced in MB than TB groups as also expressed by down-regulation of the gene Cyp8b1. The composition of the caecal microbiota in rats fed MB and TB was separated from the group fed the HFC diet, and also the LF diet, as evidenced by the absence of the phylum TM7 and reduced abundance of the genera Dorea (similar to LF-fed rats) and rc4-4. Notably, the caecal abundance of Mucispirillum was markedly increased in the MB group compared with the HFC group. The results suggest that dietary supplementation of MB and TB can be used to counteract disturbances associated with a HFC diet, by altering the gut microbiota, and decreasing liver lipids and succinic acid concentrations.