The interaction of butyrate with TNF-α during differentiation and apoptosis of colon epithelial cells: Role of NF-κB activation

Microbial dysbiosis and epigenetics modulation in cancer development - A chemopreventive approach

An overwhelming number of research articles have reported a strong relationship of the microbiome with cancer. Microbes have been observed more commonly in the body fluids like urine, stool, mucus of people with cancer compared to the healthy controls. The microbiota is responsible for both progression and suppression activities of various diseases. Thus, to maintain healthy human physiology, host and microbiota relationship should be in a balanced state. Any disturbance in this equilibrium, referred as microbiome dysbiosis becomes a prime cause for the human body to become more prone to immunodeficiency and cancer. It is well established that some of these microbes are the causative agents, whereas others may encourage the formation of tumours, but very little is known about how these microbial communications causing change at gene and epigenome level and trigger as well as encourage the tumour growth. Various studies have reported that microbes in the gut influence DNA methylation, DNA repair and DNA damage. The genes and pathways that are altered by gut microbes are also associated with cancer advancement, predominantly those implicated in cell growth and cell signalling pathways. This study exhaustively reviews the current research advancements in understanding of dysbiosis linked with colon, lung, ovarian, breast cancers and insights into the potential molecular targets of the microbiome promoting carcinogenesis, the epigenetic alterations of various potential targets by altered microbiota, as well as the role of various chemopreventive agents for timely prevention and customized treatment against various types of cancers.

Effects of dietary butyrate supplementation and oral nonsteroidal anti-inflammatory drug administration on serum inflammatory markers and productivity of dairy cows during the calving transition

Dairy cattle experience inflammation during the calving transition period, and butyrate and nonsteroidal anti-inflammatory drugs (NSAID) are expected to reduce the inflammation. Our objective was to evaluate the effects of dietary butyrate supplementation and oral NSAID administration on feed intake, serum inflammatory markers, plasma metabolites, and milk production of dairy cows during the calving transition period. Eighty-three Holstein cows were used in the experiment with a 2 × 2 factorial arrangement of treatments. The cows were blocked by parity and calving date, and randomly assigned to a dietary butyrate or control supplement, and NSAID or a placebo oral administration. Experimental diets were iso-energetic containing calcium butyrate at 1.42% of diet dry matter (DM) or the control supplement (1.04% commercial fat supplement and 0.38% calcium carbonate of diet DM). The close-up diets contained 13.3% starch and 42.4% neutral detergent fiber on a DM basis, and were fed from 28 d before expected calving date until calving. The postpartum diets contained 22.1% starch and 34.1% neutral detergent fiber on a DM basis and were fed from calving to 24 d after calving. Oral NSAID (1 mg of meloxicam/kg of body weight) or placebo (food dye) was administered 12 to 24 h after calving. Dietary butyrate supplementation and oral NSAID administration did not affect milk yield or postpartum serum concentrations of amyloid A and haptoglobin. However, butyrate-fed cows increased plasma fatty acid concentration on d -4 relative to calving (501 vs. 340 μEq/L) and tended to increase serum haptoglobin concentration (0.23 vs. 0.10 mg/mL). There was a supplement by drug interaction effect on plasma glucose concentration on d 4; in cows administered the placebo drug, butyrate supplementation decreased plasma glucose concentration compared with control-fed cows (62.8 vs. 70.1 mg/dL). Butyrate-fed cows tended to have lower milk crude protein yield compared with cows fed the control diet (1.21 vs. 1.27 kg/d). Dietary butyrate supplementation and oral NSAID administration did not have overall positive effects on production performance of dairy cows during the calving transition period.

Tumor Necrosis Factor Alpha Signaling and Organogenesis

Tumor necrosis factor alpha (TNF-α) plays important roles in processes such as immunomodulation, fever, inflammatory response, inhibition of tumor formation, and inhibition of viral replication. TNF-α and its receptors are ubiquitously expressed in developing organs and they regulate the survival, proliferation, and apoptosis of embryonic stem cells (ESCs) and progenitor cells. TNF-α is an important inflammatory factor that also regulates the inflammatory response during organogenesis, and its cytotoxic effects can interfere with normal developmental processes, even leading to the onset of diseases. This review summarizes the various roles of TNF-α in organogenesis in terms of its secreting pattern, concentration-dependent activities, and interactions with other signaling pathways. We also explored new potential functions of TNF-α.

Microbial Alterations and Risk Factors of Breast Cancer: Connections and Mechanistic Insights

Breast cancer-related mortality remains high worldwide, despite tremendous advances in diagnostics and therapeutics; hence, the quest for better strategies for disease management, as well as the identification of modifiable risk factors, continues. With recent leaps in genomic technologies, microbiota have emerged as major players in most cancers, including breast cancer. Interestingly, microbial alterations have been observed with some of the established risk factors of breast cancer, such as obesity, aging and periodontal disease. Higher levels of estrogen, a risk factor for breast cancer that cross-talks with other risk factors such as alcohol intake, obesity, parity, breastfeeding, early menarche and late menopause, are also modulated by microbial dysbiosis. In this review, we discuss the association between known breast cancer risk factors and altered microbiota. An important question related to microbial dysbiosis and cancer is the underlying mechanisms by which alterations in microbiota can support cancer progression. To this end, we review the involvement of microbial metabolites as effector molecules, the modulation of the metabolism of xenobiotics, the induction of systemic immune modulation, and altered responses to therapy owing to microbial dysbiosis. Given the association of breast cancer risk factors with microbial dysbiosis and the multitude of mechanisms altered by dysbiotic microbiota, an impaired microbiome is, in itself, an important risk factor.

Effects of butyrate supplementation on blood glucagon-like peptide-2 concentration and gastrointestinal functions of lactating dairy cows fed diets differing in starch content

The objective of this study was to evaluate effects of butyrate supplementation on plasma concentration of glucagon-like peptide-2 (GLP-2), apparent total-tract digestibility, and responses to a grain challenge of lactating dairy cows fed diets differing in starch content. Eight Holstein cows averaging 58.6 ± 9.96 d in milk (4 primiparous cows fitted with rumen cannula and 4 multiparous intact cows) were blocked by parity and assigned to one of two 4 × 4 Latin squares balanced for carryover effects with a 2 × 2 factorial arrangement of treatments. Treatments were dietary starch content [20.6 vs. 27.5%, respectively, for low starch (LS) and high starch (HS)] and butyrate supplementation (butyrate vs. control) with 21-d periods. Butyrate was provided as Gustor BP70 WS (Norel, S.A., Madrid, Spain), containing 70% sodium butyrate and 30% fatty acid mixture, at 2% of dietary dry matter (providing butyrate at 1.1% of dietary dry matter), and control premix contained 70% wheat bran and 30% fatty acid mixture. Feeds, orts, and fecal samples were collected from d 17 to 19 to determine apparent total-tract nutrient digestibility. Blood and rumen fluid samples were collected on d 19. The baseline of dry matter intake (DMI) was determined as average DMI from d 17 to 19 for each cow, and cows were feed-restricted at 60% of the baseline DMI on d 20, and a grain challenge was conducted by providing steam-flaked corn grain at 0.6% of body weight, on an as-fed basis, in addition to each treatment diet on d 21, and blood and ruminal fluid samples were collected. The interaction of dietary starch content by butyrate supplementation was significant for plasma GLP-2 concentration, being greater for cows fed butyrate with the HS diet than those fed the other 3 diets. Cows fed butyrate increased n-butyrate concentration in the ruminal fluid and tended to increase dry matter and organic matter digestibility compared with the control. During the grain challenge, rumen endotoxin concentration increased over time and was higher for cows fed the HS diets compared with those fed LS diets. However, response variables related to inflammation were not affected by the grain challenge. However, serum haptoglobin, lipopolysaccharide-binding protein, and serum amyloid-A concentrations were greater for cows fed butyrate with the LS diet, but not for those fed the HS diet. These results indicate that butyrate supplementation may increase plasma GLP-2 concentration for cows fed HS diets, and total-tract digestibility regardless of dietary starch content. However, butyrate supplementation did not mitigate inflammation in this study.

Dietary vitamin A affects growth performance, intestinal development, and functions in weaned piglets by affecting intestinal stem cells

Vitamin A (VA) is an important nutrient for weaning piglets. It plays a significant role in the normal formation, development, and maintenance of epithelial cells. Previous studies have shown that VA supplements could improve the host's intestinal barrier function. Therefore, we hypothesized that VA supplements can affect intestinal function in weaned piglets by regulating intestinal stem cells. Thirty-two 21-d-old weaned [(Yorkshire × Landrace) × Duroc] piglets with an average weight of 8.34 ± 0.13 kg were randomly divided into 4 treatment groups, with 1) 2 mg/kg (control), 2) 4 mg/kg, 3) 8 mg/kg, and 4) 16 mg/kg doses of VA, respectively. The experiment lasted for 14 d. Weaned piglets were given ad libitum access to food and water during the test. The ADG (linear, P = 0.020) and G:F (linear, P = 0.005) of the piglets were found to increase significantly from days 8 to 14. The Lgr5+ gene expression (P = 0.012) in the jejunum mucosa of the 16 mg/kg VA group was increased. The jejunum villus height (P = 0.027) and villi surface area (P = 0.035) were significantly increased in the 4 mg/kg VA treatment group. The crypt depth increased significantly in the 4 and 8 mg/kg VA treatment groups (quadratic, P = 0.043), and the ratios of villus height to crypt depth significantly increased in the 16 mg/kg VA group (quadratic, P = 0.015). The maltase (P = 0.032), sucrose (P = 0.041), and alkaline phosphatase activity (linear, P = 0.024) were significantly increased when further supplemented with 4 mg/kg VA. Slc2a2 mRNA abundance was significantly increased in the 2 mg/kg VA group (linear, P = 0.024). Moreover, the budding rates, buddings number per organoid, and Chromogranin A and Muc2 expression of piglet intestinal organoids were significantly reduced (P < 0.05) by VA and its metabolites (retinoic acid). Compared with the control group, the expression of Spp1 and Trop2 increased. These results indicated that VA may increase the stemness of intestinal stem cell in vitro. This study suggested that VA could affect growth performance and intestinal function by regulating intestinal stem cells in the jejunum of weaned piglets.

Butyrate upregulates the TLR4 expression and the phosphorylation of MAPKs and NK-κB in colon cancer cell in vitro

Microbiota and its induced inflammation in colorectal mucosa have been considered risk factors for the development of colorectal carcinogenesis. Previous studies demonstrated that the coexisting elements of microbiota in the gut, such as short chain fatty acids (SCFAs) and lipopolysaccharides (LPS), which exhibited regulatory effects on the intestinal epithelial cells individually. Unfortunately, the association between butyrate and the toll-like receptor (TLR) signaling pathway in the development of colon cancer is not fully elucidated. In the present study, by culturing human colon cancer SW480 cells or mouse colon cancer CT26 cells with butyrate and/or TLR4 ligand LPS in vitro, it was identified that butyrate suppressed the growth and promoted apoptosis of these cancer cells. Notably, the expression levels of TLR4 and CD14 were markedly increased on these butyrate-treated cells, but not on LPS-alone treated cells. Additionally, butyrate treatment induced the phosphorylation of extracellular signal-regulated kinase, tumor protein 38, c-Jun NH2-terminal kinase and nuclear factor-κB (NF-κB) p65, and then promoted the pro-inflammatory cytokine tumor necrosis factor-α, but not interleukin 6 secretion in SW480 and CT26 cells. Therefore, butyrate treatment regulates the expression of TLR4, mitogen-activated protein kinase and NF-κB signal pathway activation and pro-inflammatory response in vitro. Although the exact mechanisms have not been fully explored, these results suggested that butyrate and LPS-TLR4 signaling mediated innate immunity in colon cancer cells through two distinct but inter-regulated pathways. Thus, butyrate can further initiate innate immunity against tumor cells by upregulating the TLR4 expression and activation to preserve intestinal homeostasis.

Butyrate Supplementation at High Concentrations Alters Enteric Bacterial Communities and Reduces Intestinal Inflammation in Mice Infected with Citrobacter rodentium

The study findings provide evidence that administration of butyrate in a dose-dependent manner can improve the weight gain of infected mice, enhance clearance of the infection, reduce inflammation through altered cytokine expression, and enhance tissue repair and mucus secretion. Moreover, butyrate treatment also affected the abundance of bacterial populations in both noninflamed and inflamed intestines. Notably, this investigation provides foundational information that can be used to determine the effects of prebiotics and other functional foods on the production of butyrate by enteric bacteria and their impact on intestinal health and host well-being.

Butyrate is a short-chain fatty acid by-product of the microbial fermentation of dietary fermentable materials in the large intestine; it is the main energy source for enterocyte regeneration, modulates the enteric microbial community, and contributes to increasing host health via mechanisms that are relatively poorly defined. Limited research has examined the therapeutic potential of butyrate using models of enteric inflammation incited by pathogenic organisms. We used Citrobacter rodentium to incite acute Th1/Th17 inflammation to ascertain the impact of butyrate on the host-microbiota relationship. Rectal administration of 140 mM butyrate to mice increased fecal concentrations of butyrate and increased food consumption and weight gain in mice infected with C. rodentium. Histological scores of colonic inflammation were lower in infected mice administered 140 mM butyrate. Expression of Il10, Tgfβ, and Muc2 was elevated in noninfected mice administered butyrate in comparison to mice not administered butyrate. Infected mice administered butyrate displayed elevated expression of genes necessary for pathogen clearance (i.e., Il17A and Il1β) and of genes involved in epithelial barrier repair and restoration (i.e., Relmβ, Tff3, and Myd88). Butyrate supplemented to inflamed colons increased the abundances of Proteobacteria and Lachnospiraceae and reduced the abundance of Clostridiaceae species. Mice with enteritis that were administered butyrate also exhibited an increased abundance of mucus-associated bacteria. In summary, rectal administration of butyrate increased feed consumption and weight gain, ameliorated C. rodentium-induced cell injury through enhanced expression of immune regulation and tissue repair mechanisms, and increased the abundance of butyrate-producing bacteria in mice with enteritis.

IMPORTANCE The study findings provide evidence that administration of butyrate in a dose-dependent manner can increase weight gain in infected mice, enhance clearance of the infection, reduce inflammation through altered cytokine expression, and enhance tissue repair and mucus secretion. Moreover, butyrate treatment also affected the abundance of bacterial populations in both noninflamed and inflamed intestines. Notably, this investigation provides foundational information that can be used to determine the effects of prebiotics and other functional foods on the production of butyrate by enteric bacteria and their impact on intestinal health and host well-being.

Influences of diet and the gut microbiome on epigenetic modulation in cancer and other diseases

Epigenetic modulation of gene activity occurs in response to non-genetic factors such as body weight status, physical activity, dietary factors, and environmental toxins. In addition, each of these factors is thought to affect and be affected by the gut microbiome. A primary mechanism that links these various factors together in mediating control of gene expression is the production of metabolites that serve as critical cofactors and allosteric regulators of epigenetic processes. Here, we review the involvement of the gut microbiota and its interactions with dietary factors, many of which have known cellular bioactivity, focusing on particular epigenetic processes affected and the influence they have on human health and disease, particularly cancer and response to treatment. Advances in DNA sequencing have expanded the capacity for studying the microbiome. Combining this with rapidly improving techniques to measure the metabolome provides opportunities to understand complex relationships that may underlie the development and progression of cancer as well as treatment-related sequelae. Given broad reaching and fundamental biology, both at the cellular and organismal levels, we propose that interactive research programs, which utilize a wide range of mutually informative experimental model systems—each one optimally suited for answering particular questions—provide the best path forward for breaking ground on new knowledge and ultimately understanding the epigenetic significance of the gut microbiome and its response to dietary factors in cancer prevention and therapy.

Alkaline phosphatase in stem cells

Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. In humans and other mammals, determinations of the expression and activity of alkaline phosphatase have frequently been used for cell determination in developmental studies and/or within clinical trials. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail. First, we briefly summarize contemporary knowledge of mammalian alkaline phosphatases in general. Second, we focus on the known facts of its role in and potential significance for the identification of stem cells.

Interaction of dietary fatty acids with tumour necrosis factor family cytokines during colon inflammation and cancer

Intestinal homeostasis is precisely regulated by a number of endogenous regulatory molecules but significantly influenced by dietary compounds. Malfunction of this system may result in chronic inflammation and cancer. Dietary essential n-3 polyunsaturated fatty acids (PUFAs) and short-chain fatty acid butyrate produced from fibre display anti-inflammatory and anticancer activities. Both compounds were shown to modulate the production and activities of TNF family cytokines. Cytokines from the TNF family (TNF- α, TRAIL, and FasL) have potent inflammatory activities and can also regulate apoptosis, which plays an important role in cancer development. The results of our own research showed enhancement of apoptosis in colon cancer cells by a combination of either docosahexaenoic acid (DHA) or butyrate with TNF family cytokines, especially by promotion of the mitochondrial apoptotic pathway and modulation of NF κ B activity. This review is focused mainly on the interaction of dietary PUFAs and butyrate with these cytokines during colon inflammation and cancer development. We summarised recent knowledge about the cellular and molecular mechanisms involved in such effects and outcomes for intestinal cell behaviour and pathologies. Finally, the possible application for the prevention and therapy of colon inflammation and cancer is also outlined.

ICAD deficiency in human colon cancer and predisposition to colon tumorigenesis: linkage to apoptosis resistance and genomic instability

We previously showed that DNA fragmentation factor, which comprises a caspase-3-activated DNase (CAD) and its inhibitor (ICAD), may influence the rate of cell death by generating PARP-1-activating DNA breaks. Here we tested the hypothesis that ICAD-deficient colon epithelial cells exhibiting resistance to death stimuli may accumulate additional genetic modifications, leading to a tumorigenic phenotype. We show that ICAD deficiency may be associated with colon malignancy in humans. Indeed, an examination of ICAD expression using immunohistochemistry in an array of both colon cancer and normal tissues revealed that ICAD expression levels were severely compromised in the cancerous tissues. Upon DNA damage caused by a low dose of irradiation, ICAD cells acquire a tumorigenic phenotype. Colon epithelial cells derived from ICAD mice showed a significant resistance to death induced by the colon carcinogen dimethylhydrazine in vitro and in mice. Such resistance was associated with a decrease in PARP-1 activation. In an animal model of dimethylhydrazine-induced colon tumorigenesis, ICAD^−/− mice developed significantly higher numbers of tumors with markedly larger sizes than the wild-type counterparts. Interestingly, the phenotype of the ICAD^−/− mice was not associated with a significant increase in the precancerous aberrant crypt foci suggesting a potential link to tumor progression rather than initiation. More importantly, ICAD deficiency was associated with severe genomic instability as assessed by array comparative genomic hybridization. Such genomic instability consisted most prominently of amplifications but with sizable deletions as compared to the wild-type counterparts affecting several cancer-related genes including RAF-1, GSN, LMO3, and Fzd6 independently of p53. Altogether, our results present a viable case for the involvement of ICAD deficiency in colon carcinogenesis and show that apoptosis and genomic instability may comprise the means by which such deficiency may contribute to the process of increasing susceptibility to carcinogen-induced tumorigenesis.

Impact of early reoperation after resection for colorectal cancer on long-term oncological outcomes

AIM

Whether reoperation in the postoperative period adversely affects oncologic outcomes for colorectal cancer patients undergoing resection has not been well characterized. The aim of this study was to determine whether long-term oncological outcomes are affected for patients who undergo repeat surgery in the early postoperative period.

METHOD

From a prospective colorectal cancer database, patients who underwent resection for colorectal cancer between 1982 and 2008 and were reoperated within 30 days after surgery (group A) were matched for age (±5 years), gender, year of surgery (±2 years), American Society of Anesthesiology score, tumor site (colon or rectum), cancer stage and differentiation with patients who did not undergo reoperation (group B). The two groups were compared for overall survival (OS), disease-free survival (DFS) and local recurrence (LR).

RESULTS

In total, 89 reoperated patients (45 rectal, 44 colon cancer) were matched to an equal number of non-reoperated patients. Anterior resection (39.2%) and right hemicolectomy (19.1%) were predominant primary operations. Indications for reoperation were anastomotic leak/abscess (n=40, 45%), massive bleeding (n=15, 16.9%), bowel obstruction (n=11, 12.4%), wound complications (n=9, 10.1%) and other indications (n=14, 15.6%). Group A had significantly greater overall morbidity (100% vs 27%, P=0.001) and required more blood transfusions (20.2% vs 7.9%, P=0.045). Adjuvant therapy use, on the other hand, was more common in group B (23.6% vs 12.3%, P=0.1). The 5-year OS and DFS were lower in the reoperated group (OS 55.3% vs 66.4%, P=0.02; DFS 50.8% vs 60.8%, P=0.06, respectively). Five-year LR was slightly lower in the reoperated group (2.9% vs 6.3%, P=0.34).

CONCLUSIONS

Compared with non-reoperated patients matched for patient, tumour and operative characteristics, patients reoperated in the early postoperative period have worse long-term oncological outcomes. Adoption of strategies to reduce the risk of reoperation may be associated with the additional advantage of improved oncological outcomes in addition to the short-term advantages.

Synbiotic intervention of Bifidobacterium lactis and resistant starch protects against colorectal cancer development in rats

This study evaluated the effect of a probiotic bacteria 'Bifidobacterium lactis', the carbohydrate 'resistant starch' (RS) and their combination (synbiotic), on their ability to protect against colorectal cancer (CRC). Bifidobacterium lactis has been shown previously to utilize RS as a substrate and up-regulate the acute apoptotic response to a carcinogen in the colon [Le Leu et al. (2005) J. Nutr., 135, 996-1001]. Sprague-Dawley rats were divided into six equal groups and fed semi-purified diets for 30 weeks. Colonic neoplasms were induced by 2 weekly injections of azoxymethane (15 mg/kg body wt). The experimental groups were as follows: control-no added dietary fibre or RS; RS in two forms-Hi-maize 958 or Hi-maize 260; B.lactis (lyophilized)-added to control and RS diets (six treatment groups in all). Rats fed RS in combination with B.lactis showed significantly lowered incidence and multiplicity of colonic neoplasms (P < 0.01) by >50% compared with the control group. There was a trend for protection by RS alone (P = 0.07), whereas no protection against cancer was seen in the group supplemented with only B.lactis. Fermentation events [short-chain fatty acid (SCFA), pH] were altered by the inclusion of RS into the diet, whereas the inclusion of B.lactis into the diet had no significant effect on the fermentation parameters. The synbiotic combination of RS and B.lactis significantly protects against the development of CRC in the rat-azoxymethane model. Synbiotic combination of prebiotic and probiotic seems likely to be a superior preventive strategy to prebiotic alone.

Monocytic differentiation of leukemic HL-60 cells induced by co-treatment with TNF-alpha and MK886 requires activation of pro-apoptotic machinery

The block of hematopoietic differentiation program in acute myeloid leukemia cells can be overcome by differentiating agent like retinoic acid, but it has several side effects. A study of other differentiation signaling pathways is therefore useful to predict potential targets of anti-leukemic therapy. We demonstrated previously that the co-treatment of HL-60 cells with Tumor necrosis factor-alpha (TNF-alpha) (1 ng/mL) and inhibitor of 5-lipoxygenase MK886 (5 microm) potentiated both monocytic differentiation and apoptosis. In this study, we detected enhanced activation of three main types of mitogen-activated protein kinases (MAPKs) (p38, c-Jun amino-terminal kinase [JNK], extracellular signal-regulated kinase [ERK]), so we assessed their role in differentiation using appropriate pharmacologic inhibitors. The inhibition of pro-apoptotic MAPKs (p38 and JNK) suppressed the effect of MK886 + TNF-alpha co-treatment. On the other hand, down-regulation of pro-survival ERK pathway led to increased differentiation. Those effects were accompanied by increased activation of caspases in cells treated by MK886 + TNF-alpha. Pan-caspase inhibitor ZVAD-fmk significantly decreased both number of apoptotic and differentiated cells. The same effect was observed after inhibition of caspase 9, but not caspase 3 and 8. To conclude, we evidenced that the activation of apoptotic processes and pathways supporting apoptosis (p38 and JNK MAPKs) is required for the monocytic differentiation of HL-60 cells.