Effects of sodium butyrate on expression of members of the IGF-binding protein superfamily in human mammary epithelial cells

Faecal Microbiota of Dogs Offered a Vegetarian Diet with or without the Supplementation of Feather Meal and either Cornmeal, Rye or Fermented Rye: A Preliminary Study

Anthropomorphism of dogs has affected feeding and the choice of components present in diets for dogs. Conflicting trends are present: raw or vegetarian appear more prevalent. Animal-derived proteins seem to have unfavourable impacts on intestinal microflora by decreasing the presence of Bacteroidetes. This preliminary study evaluates whether effects of diets with animal proteins on intestinal microbiota can be compensated by the addition of certain carbohydrates to dog diet. Eight female beagles were included in a cross-over study and fed a vegetarian diet or the same diet supplemented with feather meal (2.7%) and either 20% of cornmeal, fermented or non-fermented rye (moisture content of the diets about 42%). A 16S rRNA gene amplification was performed within the hypervariable region V4 on faecal samples and sequenced with the Illumina MiSeq platform. The Firmicutes/Bacteroidetes ratio tended to shift to the advantage of Firmicutes when feather meal and cornmeal were added (Firmicutes/Bacteroidetes ratio of 5.12 compared to 2.47 when offered the vegetarian diet) and tended to switch back to the advantage of Bacteroidetes if rye: fermented (2.17) or not (1.03) was added. The addition of rye might have the potential to compensate possible unfavourable effects of diets with animal proteins on intestinal microbiota of dogs.

Analysis of the IGF-system in milk from farm animals - Occurrence, regulation, and biomarker potential

IGFs and IGF-binding proteins (IGFBPs) are abundantly present in milk and in dairy products. Compared to the IGFs, the IGFBP have received less attention in milk, although truncated IGFBPs and IGFBP-glycosylation have been described in milk. Thereby, complex control of local IGF-effects can be assumed on the levels of IGFBPs, proteases, and protease inhibitors. The present review collects the current knowledge both on presence and regulation of IGFs and IGFBPs in milk particularly from dairy animal species. As a rule higher levels of IGF-I, IGF-II, and IGFBPs are measured around parturition if compared to later time-points of lactation. In all farm animal species included in this review, it is found that the relative abundancies of IGFBPs in milk and serum are similar, with IGFBP-3 and -2 characterized by higher concentrations if compared to IGFBP-4 or -5. The concentrations of IGFs and IGFBPs in milk or dairy products can be altered by hormones, dairy processing, or fermentation. Because milk can be used for non-invasive biomarker research, quality management, and health monitoring, we discuss novel directions of IGF-analysis and potential on-site biomarker research in milk.

The histone deacetylase inhibitor, sodium butyrate, exhibits neuroprotective effects for ischemic stroke in middle-aged female rats

Background

Sodium butyrate (NaB) is a histone deacetylase (HDAC) inhibitor exhibiting anti-inflammatory and neuroprotective effects in a rat ischemic model of stroke as well as a myocardial ischemia model. Although clinical evidence shows that older women are at higher risk for stroke occurrence and greater stroke severity, no studies have evaluated the effectiveness of NaB either in females or in older animals.

Methods

To determine the effects of NaB on stroke in older females, acyclic middle-aged Sprague-Dawley female rats (9–11 months old, constant diestrus) were subject to middle cerebral artery occlusion (MCAo) by intracerebral injection of recombinant endothelin-1. Rats were treated with NaB (300 mg/kg, i.p.) at 6 and 30 h following ET-1 injection. Animals were sacrificed at the early (2 days) or late (5 days) acute phase after MCAo. Serum and tissue lysates were collected for biochemical analyses.

Results

NaB treatment reduced infarct volume and ameliorated sensory motor impairment in middle-aged female rats, when measured at 2 and 5 days post MCAo. At the early acute phase (2 days post stroke), NaB treatment decreased brain lipid peroxides, and reduced serum levels of GFAP, a surrogate marker of blood-brain barrier (BBB) permeability. NaB also reduced expression of the inflammatory cytokine IL-1beta in circulation and IL-18 in the ischemic hemisphere. At the late acute phase (5 days post stroke), NaB treatment further suppressed MCAo-induced increase of IL-1beta, IL-17A, and IL-18 in brain lysates (cortex and striatum) from the ischemic hemisphere, and decreased ischemia-induced upregulation of IL-1beta and IL-18 in circulation, indicating a potent anti-inflammatory effect of the HDAC inhibitor. Moreover, NaB treatment also increased expression of IGF-1, a known neuroprotectant, in peripheral tissue including serum, liver, and spleen at the late acute phase.

Conclusions

These data provide the first evidence that delayed (>6 h) NaB treatment post-stroke is neuroprotective in older female rats. Additionally, these data also show that in addition to its well-known anti-inflammatory actions, NaB may exert a biphasic effect after stroke, operating initially to reduce BBB permeability and oxidative stress in the brain, and later, elevating IGF-1 expression in peripheral tissues.

Effects of Na-butyrate supplementation in milk formula on plasma concentrations of GH and insulin, and on rumen papilla development in calves

Although the growth-promoting action of sodium-butyrate (Na-butyrate) used as a feed additive has been observed in calves and pigs, the precise mechanisms involved remain to be clarified. In this study, pre-weaning calves were given milk formula (MF) supplemented with butyrate for 6 weeks to investigate its effects on postprandial changes in the plasma concentrations of metabolic hormones, and, simultaneously, on growth performance, the weight of the digestive organs and rumen papilla development. Ingestion of MF increased (P<0.05) the plasma concentrations of GH and insulin as well as the glucose level, but decreased the non-esterified fatty acid concentration. Na-butyrate supplementation in MF or in lactose solution (with the same quantity of lactose contained in the MF, 5%) suppressed the increase in plasma insulin and GH concentrations, and the plasma IGF1 level was not changed. The length of the rumen papilla and the weight of the perirenal fat tended to increase in the calves fed with Na-butyrate-supplemented MF, but the weight of the liver, spleen, and stomach were not changed. In addition, there was no difference in the expression of mRNA for sodium-dependent glucose transporter-1 in the small intestinal epithelial tissues. We conclude that the accelerated growth performance related to the intake of Na-butyrate used as a feed additive reported previously in several species is partly due to improved insulin sensitivity and a better digestive functional development. These data could be applicable to animal and human nutrition.

From the gut to the peripheral tissues: the multiple effects of butyrate

Butyrate is a natural substance present in biological liquids and tissues. The present paper aims to give an update on the biological role of butyrate in mammals, when it is naturally produced by the gastrointestinal microbiota or orally ingested as a feed additive. Recent data concerning butyrate production delivery as well as absorption by the colonocytes are reported. Butyrate cannot be detected in the peripheral blood, which indicates fast metabolism in the gut wall and/or in the liver. In physiological conditions, the increase in performance in animals could be explained by the increased nutrient digestibility, the stimulation of the digestive enzyme secretions, a modification of intestinal luminal microbiota and an improvement of the epithelial integrity and defence systems. In the digestive tract, butyrate can act directly (upper gastrointestinal tract or hindgut) or indirectly (small intestine) on tissue development and repair. Direct trophic effects have been demonstrated mainly by cell proliferation studies, indicating a faster renewal of necrotic areas. Indirect actions of butyrate are believed to involve the hormono-neuro-immuno system. Butyrate has also been implicated in down-regulation of bacteria virulence, both by direct effects on virulence gene expression and by acting on cell proliferation of the host cells. In animal production, butyrate is a helpful feed additive, especially when ingested soon after birth, as it enhances performance and controls gut health disorders caused by bacterial pathogens. Such effects could be considered for new applications in human nutrition.

Unraveling insulin-like growth factor binding protein-3 actions in human disease

The IGF system plays critical roles in somatic growth in an endocrine fashion (somatomedin hypothesis) as well as proliferation and differentiation of normal and malignant cells in a paracrine/autocrine fashion. IGFBP-3 is known to modulate the actions of IGFs in circulation as well as the immediate extracellular environment. Interestingly, apart from the ability to inhibit or enhance IGF actions, IGFBP-3 also exhibits very clear, distinct biological effects independent of the IGF/IGF-I receptor axis. Over the past decade it has become widely appreciated that IGF/IGF-IR-independent actions of IGFBP-3 (antiproliferative and proapoptotic effects) contribute to improving the pathophysiology of a variety of human diseases, such as cancer, diabetes, and malnutrition. Recent studies have implicated interaction of IGFBP-3 with a variety of proteins or signaling cascades critical to cell cycle control and apoptosis; however, the actual mechanism of IGFBP-3 action is still unclear. This review reinforces the concept in support of the IGF/IGF-IR axis-independent actions of IGFBP-3 and delineates potential underlying mechanisms involved and subsequent biological significance, focusing in particular on functional binding partners and the clinical significance of IGFBP-3 in the assessment of cancer risk.

Lignans and human health

This review focuses on the possible role in human health of the consumption of lignan-rich foods. Most of the plant lignans in human foods are converted by the intestinal microflora in the upper part of the large bowel to enterolactone and enterodiol, called mammalian or enterolignans. The protective role of these compounds, particularly in chronic Western diseases, is discussed. Evidence suggests that fiber- and lignan-rich whole-grain cereals, beans, berries, nuts, and various seeds are the main protective foods. Many factors, in addition to diet, such as intestinal microflora, smoking, antibiotics, and obesity affect circulating lignan levels in the body. Lignan-rich diets may be beneficial, particularly if consumed for life. Experimental evidence in animals has shown clear anticarcinogenic effects of flaxseed or pure lignans in many types of cancer. Many epidemiological results are controversial, partly because the determinants of plasma enterolactone are very different in different countries. The source of the lignans seems to play a role because other factors in the food obviously participate in the protective effects. The results are promising, but much work is still needed in this area of medicine.

Multiple pathways regulating the anti-apoptotic protein clusterin in breast cancer

Cancer chemotherapy inhibits tumor growth, in part, by triggering apoptosis, and anti-apoptotic proteins reduce the effectiveness of chemotherapy. Clusterin, a chaperone-like protein that binds to apoptotic and DNA repair proteins, is induced by chemotherapy and promotes tumor cell survival. Histone deacetylase inhibitors (HDIs) such as sodium butyrate and suberoylanilide hydroxamic acid (SAHA) are pharmacological agents that induce differentiation and apoptosis in cancer cells by altering chromatin structure, and we have found that combinations of chemotherapeutic drugs such as doxorubicin and HDIs efficiently induce apoptosis, even though they paradoxically induce high levels of clusterin. The hyper-expressed form of clusterin localizes to mitochondria, inhibits cytochrome c release, and is inhibited by the proteasome. When HDIs are used as single agents, clusterin suppresses cytochrome c release and apoptosis. However, doxorubicin/HDI-induced apoptosis is not inhibited by clusterin, and clusterin-resistant apoptosis corresponds with markers of the extrinsic/receptor-mediated apoptotic pathway. Thus, chemotherapy-HDI combinations are capable of overcoming an innate anti-apoptotic pathway of tumor cells, suggesting that chemotherapy-HDI combinations have potential for treating advanced stage breast cancer.

Growth inhibitory concentrations of androgens up-regulate insulin-like growth factor binding protein-3 expression via an androgen response element in LNCaP human prostate cancer cells

IGF binding protein-3 (IGFBP-3), the most abundant circulating IGF binding protein, inhibits cell growth and induces apoptosis by both IGF-I-dependent and -independent pathways. The ability of IGFBP-3 to inhibit tumor growth has been demonstrated in many cancers including prostate cancer (PCa). High concentrations of androgens, which inhibit the growth of the LNCaP human PCa cell line, have been shown to have both positive and negative effects on IGFBP-3 expression by different laboratories. To further explore the relationship between IGFBP-3 and androgens, we examined IGFBP-3 expression in LNCaP cells. We demonstrate that IGFBP-3 expression can be induced by 10 nm of the synthetic androgen R1881 or dihydrotestosterone. Transactivation assays show that the 6-kb IGFBP-3 promoter sequence directly responds to androgen treatment. In silico analysis identified a putative androgen response element (ARE) at -2,879/-2,865 in the IGFBP-3 promoter. A single point mutation in this ARE disrupted transactivation by R1881. Combining the data obtained from EMSA, chromatin immunoprecipitation and mutational analysis, we conclude that a novel functional ARE is present in the IGFBP-3 promoter that directly mediates androgen induction of IGFBP-3 expression. Furthermore, we found that the combination of androgens and calcitriol significantly potentiated the IGFBP-3 promoter activity, suggesting that enhanced induction of the expression of the endogenous IGFBP-3 gene may contribute to the greater inhibition of LNCaP cell growth by combined calcitriol and androgens. Because androgens are well known to stimulate PCa growth and androgen deprivation therapy causes PCa to regress, the stimulation by androgens of this antiproliferative and proapoptotic protein is paradoxical and raises interesting questions about the role of androgen-stimulated IGFBP-3 in PCa.

Effects of butyrate, avilamycin, and a plant extract combination on the intestinal equilibrium of early-weaned pigs1

We evaluated the effects of 3 additives, sodium butyrate (AC), avilamycin (AB), and a combination of plant extracts (XT), on the productive performance and the intestinal environment of the early-weaned pig. The XT was a standardized mixture with 5% (wt/wt) carvacrol (from Origanum spp.), 3% cinnamaldehyde (from Cinnamonum spp.), and 2% capsicum oleoresin (from Capsicum annum). Pigs (n = 32) weaned at 18 to 22 d of age with an initial BW of 6.0 +/- 0.10 kg were allocated to 8 pens that, in turn, were allocated to 4 treatments. The treatments included a basal diet (CT) or the basal diet supplemented with 0.3% of AC, 0.04% of AB, or 0.03% of XT. Productive performance was determined during the initial 14 d postweaning. On d 19 and 21 of the experiment, the pigs were killed to allow collection of digesta and intestinal tissue to evaluate variables indicative of aspects of the gastrointestinal environment. Treatments AB and AC improved G:F (P = 0.012 and 0.003, respectively) compared with the CT. Butyrate included in the diet was only detected in the stomach but not in cranial jejunum. When compared with CT, AC produced a lower ileal starch digestibility (P = 0.002) and a lower whole-tract OM and starch digestibility (P = 0.001 and 0.003, respectively), related to a lower VFA concentration in the cranial colon (P = 0.082) and a numerically reduced branched VFA percentage in the rectum. The AB treatment diminished propionate production in caudal colon (P = 0.002) and rectum (P = 0.012) compared with CT. The AC group exhibited deeper crypt depth in the jejunum without variations in villus height compared with CT (P = 0.042). The AC and AB groups also increased goblet cell presence in the colon (P = 0.001 and 0.032, respectively). On the other hand, AB and XT diminished intraepithelial lymphocytes in the jejunum (P = 0.003 and 0.034, respectively). The XT increased lymphocyte presence in the colon (P = 0.003). These results show the important influence of AB and AC on productive performance and on pig gut dynamics. The intestinal modifications observed for AB and AC compared with CT suggest distinct modes of action for each additive.

Butyrate-induced collagen biosynthesis in cultured fibroblasts is independent on alpha2beta1 integrin signalling and undergoes through IGF-I receptor cascade

The potential role of butyrate to modulate cellular metabolism through integrin receptor led to evaluation of its effect on collagen biosynthesis in cultured fibroblasts. Confluent human dermal fibroblasts were treated with 2 mM and 4 mM of sodium butyrate (NaB) for 48 h. It was found that butyrate induced collagen biosynthesis and prolidase activity independently of alpha2beta1 integrin signaling. The expressions of both alpha2 and beta1 integrin subunits as well as integrin-induced activation of focal adhesion kinase (FAK) were not affected in the cells treated with NaB. Since insulin-like growth factor-I (IGF-I) is the most potent stimulator of collagen biosynthesis in fibroblasts, the effect of butyrate on IGF-I receptor (IGF-IR) expression was evaluated. It was found that the exposure of the cells to 4 mM butyrate contributed to a distinct increase in IGF-IR. It was accompanied by a parallel increase in the expression of Sos protein and MAP-kinases (ERK1, ERK2). The data suggests that butyrate-dependent stimulation of collagen biosynthesis in cultured human skin fibroblasts undergoes through IGF-IR signaling.

EGF-mediated regulation of IGFBP-3 determines esophageal epithelial cellular response to IGF-I

IGF and EGF regulate various physiological and pathological processes. IGF binding protein (IGFBP)-3 regulates cell proliferation in IGF-dependent and -independent fashions. Recently, we identified IGFBP-3 as a novel EGF receptor (EGFR) downstream target molecule in primary and immortalized human esophageal epithelial cells, suggesting an interplay between the EGF and IGF signaling pathways. However, the regulatory mechanisms for IGFBP-3 expression and its functional role in esophageal cell proliferation remain to be elucidated. Herein, we report that IGFBP-3 mRNA and protein were induced upon growth factor deprivation in primary and immortalized human esophageal cells through mechanisms requiring p53-independent de novo mRNA transcription and protein synthesis. This occurred in the face of the activated phosphatidylinositol 3-OH-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. Secreted IGFBP-3 neutralized IGFs and prevented IGF-I receptor (IGF-IR) activation. In contrast, EGF suppressed IGFBP-3 mRNA and protein expression through activation of MAPK in an EGFR-tyrosine kinase-dependent manner to restore the cellular response to IGF-I. When stably overexpressed, wild-type IGFBP-3 but not I56G/L80G/L81G (GGG) mutant IGFBP-3, which has a reduced affinity to IGFs, prevented IGF-I from activating IGF-IR and Akt as well as stimulating cell proliferation. However, unlike other cell types where IGFBP-3 exerts antiproliferative effects, neither wild-type nor GGG mutant IGFBP-3 alone affected cell proliferation or EGFR activity. These results indicate that IGF signaling is subject to negative regulation through IGFBP-3 and positive regulation by EGF, the latter of which suppresses IGFBP-3. This provides a platform for understanding the novel cross talk between EGF- and IGF-mediated pathways.

Rye bread enhances the production and plasma concentration of butyrate but not the plasma concentrations of glucose and insulin in pigs

The present investigation was undertaken to study the gastrointestinal and physiologic properties of diets based on soft and crisp wheat and rye breads similar in dietary fiber (DF; 230-235 g/kg dry matter) but with different proportions of the main DF polymers: in wheat, cellulose, and in rye, arabinoxylans (AX). The 2 diets provided all macronutrients; consequently, they had lower fat and sugar contents and a higher DF content than human mixed diets. The nutritional properties were studied in experiments in which pigs with cannulated ilea and catheterized portal veins and mesenteric arteries served as models for humans. The characteristics studied were degradation of nutrients, flow at the ileum, fecal output, absorption of nutrients deriving from the assimilation of cereal carbohydrates, and the insulin response. Apparent viscosity at the terminal small intestine, the ileal flow of water, flow and digestibility of noncarbohydrate constituents, but not of carbohydrates at the terminal ileum or the plasma concentrations of glucose and insulin, were higher when pigs consumed the rye compared with the wheat diet. The 2 diets provided approximately equal amounts of carbohydrates available for fermentation in the large intestine but because AX from the rye diet was more degradable than cellulose from the wheat diet, the quantitative degradation in the large intestine was more than twice as high when pigs consumed the former compared with the latter diet. The consequences included moister feces and significantly enhanced gut production and plasma concentrations of butyrate when pigs consumed the rye diet compared with the wheat diet.

Epidermal growth factor-mediated inhibition of follicle-stimulating hormone-stimulated StAR gene expression in porcine granulosa cells is associated with reduced histone H3 acetylation

Steroidogenic acute regulatory protein (StAR) mediates cholesterol transport into the mitochondria and is essential for ovarian steroidogenesis. Epidermal growth factor (EGF) has been reported to inhibit FSH-stimulated differentiation in porcine granulosa cells. Previous studies have demonstrated FSH stimulates StAR mRNA accumulation and gene promoter activation in granulosa cells. Treatment of granulosa cells with FSH (5 ng/ml, 6 h) increased StAR mRNA, whereas coaddition of EGF (10 ng/ ml) significantly reduced (P < 0.05) FSH-stimulated mRNA accumulation by 62.7% +/- 13.9%. Under these same conditions, FSH-stimulated cAMP accumulation in cultures was unaltered by coincubation with EGF. RNA stability studies showed that cotreatment with FSH and EGF did not alter the StAR mRNA half-life compared with FSH alone, t(1/2) = 1.9-3.8 and 2.7-4.1 h, respectively. EGF significantly inhibited (P < 0.05) FSH-stimulated StAR heterogeneous nuclear RNA levels by 47.6% +/- 6.8 %, implicating a repressive effect on transcription. Surprisingly, EGF (1-50 ng/ml) did not affect FSH stimulation of a 1423-base pair StAR gene promoter-luciferase construct in transient transfection assays in porcine granulosa cells. To evaluate FSH and EGF effects on the endogenous StAR gene, chromatin immunoprecipitation assays were performed in combination with real-time polymerase chain reaction. FSH increased histone H3 acetylation (lysines 9, 14) within the proximal region of the StAR gene promoter and coincubation with EGF blocked this effect. Dimethylation (lysine 9) of histone H3 was not influenced by treatments. In conclusion, EGF repression of FSH-stimulated StAR transcription in porcine granulosa cells is accompanied by reductions in histone H3 acetylation associated with the StAR gene promoter.

Identification of a Functional Vitamin D Response Element in the Human Insulin-Like Growth Factor Binding Protein-3 Promoter

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] plays a critical role in maintaining calcium and phosphate homeostasis and bone formation but also exhibits antiproliferative activity on many cancer cells, including prostate cancer. We have shown that the antiproliferative actions of 1,25-(OH)2D3 in the LNCaP human prostate cancer cell line are mediated in part by induction of IGF binding protein-3 (IGFBP-3). The purpose of this study was to determine the molecular mechanism involved in 1,25-(OH)2D3 regulation of IGFBP-3 expression and to identify the putative vitamin D response element (VDRE) in the IGFBP-3 promoter. We cloned approximately 6 kb of the IGFBP-3 promoter sequence and demonstrated its responsiveness to 1,25-(OH)2D3 in transactivation assays. Computer analysis identified a putative VDRE between -3296/-3282 containing the direct repeat motif GGTTCA ccg GGTGCA that is 92% identical with the rat 24-hydroxylase distal VDRE. In EMSAs, the vitamin D receptor (VDR) showed strong binding to the putative IGFBP-3 VDRE in the presence of 1,25-(OH)2D3. Supershift assays confirmed the presence of VDR in the IGFBP-3 VDRE complex. Chromatin immunoprecipitation assay demonstrated that 1,25-(OH)2D3 recruited the VDR/retinoid X receptor heterodimer to the VDRE site in the natural IGFBP-3 promoter in intact cells. In transactivation assays, the putative VDRE coupled to a heterologous simian virus 40 promoter construct was induced 2-fold by 1,25-(OH)2D3. Mutations in the VDRE resulted in a loss of inducibility confirming the critical hexameric sequence. In conclusion, we have identified a functional VDRE in the distal region of the human IGFBP-3 promoter. The induction of IGFBP-3 by 1,25-(OH)2D3 appears to be directly mediated via VDR interaction with this VDRE.

P21(WAF1/CIP1) is dispensable for G1 arrest, but indispensable for apoptosis induced by sodium butyrate in MCF-7 breast cancer cells

Sodium butyrate (NaB) has been proposed as a potential anticancer agent. However, its mechanism of action is not totally elucidated. Here, we showed that NaB-induced cell cycle arrest and apoptosis were associated with an increase of P21(waf1/cip1) in MCF-7 breast cancer cells. This increase was more important in the nuclei, as revealed by immunofluorescence analysis. Transient transfections of MCF-7 cells with p21 deficient for interaction with CDK, but not with p21 deficient for interaction with PCNA (p21PCNA-), abrogated NaB-induced cell cycle arrest. This indicated that cell cycle blockage involved the interaction of P21(waf1/cip1) with CDK. However, P21(waf1/cip1) was dispensable, since p21 antisense did not modify cell cycle arrest. On the other hand, NaB-induced apoptosis was abolished by p21 antisense or p21PCNA-. In addition, NaB decreased PCNA levels, but increased the association of PCNA with P21(waf1/cip1). These results suggested that NaB-induced apoptosis required P21(waf1/cip1) and its interaction with PCNA.

New insight into butyrate metabolism

Butyrate is a C4 acid produced by microbial fermentation of carbohydrates and protein in the large intestine of all animal species. The factor of prime importance for the production rate of butyrate in the lower gut is type and levels of non-digestible carbohydrates entering the large intestine. It was previously believed that 85-90 % of the butyrate produced in the gut was cleared when passing the gut epithelium, but recent studies with catheterised pigs have shown that the concentration of butyrate in the portal vein is strongly influenced by the production rate in the large intestine. Increased gut production of butyrate further raises the circulating level of butyrate. For good reason it is not possible with current technologies to perform direct measurements of the variation in the butyrate concentration in the portal vein of human subjects, but short-chain fatty acid levels in portal blood from sudden-death victims, subjects undergoing emergency surgery or planned surgery have indicated a higher gut production and absolute and relative concentration of butyrate in non-fasted as compared with fasted human subjects. However, despite an expected higher gut production of butyrate when feeding a high-fibre rye-bread-based diet as compared with a low-fibre wheat-bread-based diet, there was no difference in absolute or relative levels of butyrate in the peripheral blood of human subjects.

Trichostatin A, a histone deacetylase inhibitor, activates the IGFBP-3 promoter by upregulating Sp1 activity in hepatoma cells: alteration of the Sp1/Sp3/HDAC1 multiprotein complex

We determined the molecular mechanisms by which trichostatin A (TSA) induced insulin-like growth factor-binding protein 3 (IGFBP-3) gene expression in Hep3B cells, a p53-mutant human hepatocellular carcinoma (HCC) cell line. TSA induced the expressions of the IGFBP-3 mRNA and protein and the activation of its promoter. Using IGFBP-3 promoter deletion constructs, the TSA-responsive element was mapped to a region between -115 and -30, relative to the transcription start site. Promoter mutation analysis confirmed that the TSA-responsive element coincides with the Sp1/GC-rich region on the IGFBP-3 promoter. This transcriptional activation appears to be mediated by both the Sp1 and Sp3 transcription factors and, in particular, by the phosphorylation of Sp1, because treatment of Hep3B cells and Schneider (SL2) cells with TSA significantly activated phosphorylation of Sp1 in a dose-dependent manner. Consistent with the transcriptional activation of the IGFBP-3 promoter by TSA, TSA treatment led to the release of HDAC1 and Sp3 from the Sp1 transcriptional factor complex, indicating the involvement of multiprotein complexes containing Sp1, Sp3, p300, and HDAC-1 in IGFBP-3 activation by TSA. Taken together, these results show that Sp1 phosphorylation and the modulation of the Sp1/Sp3/HDAC1 multiprotein complex play a pivotal role in the transcriptional activation of the IGFBP-3 promoter through the Sp1/GC-rich site by TSA.

Differential activation of the IGF binding protein-3 promoter by butyrate in prostate cancer cells

Sodium butyrate (NaB), a dietary micronutrient, is a potent growth inhibitor that initiates cell differentiation in many cell types, including prostate cancer cells. The molecular mechanisms by which these effects occur remain largely unknown. In this study, we investigated the effects of NaB on the expression of IGF binding protein (IGFBP)-3, a known growth regulator, in two human prostate cancer cell lines (PC-3 and LNCaP). Treatment with NaB (0-10 mM) caused a dose-dependent stimulation of IGFBP-3 mRNA expression and parallel increases in protein levels. A specific histone deacetylase inhibitor, trichostatin A (TSA) similarly induced IGFBP-3 expression, indicating that histone hyperacetylation may be critical in the regulation of IGFBP-3 expression. To investigate the molecular mechanism of NaB-regulated IGFBP-3 expression, 1.87 kb of the human IGFBP-3 gene promoter was cloned into the pGL2-basic luciferase reporter vector. In both PC-3 and LNCaP cells, NaB (10 mM) significantly increased luciferase activity 20- to 30-fold, compared with the untreated control. However, using 5' sequential deletion constructs of the IGFBP-3 promoter, the NaB response sequences in the IGFBP-3 promoter were different in PC-3 and LNCaP cells. Our studies identified a region, -75 to +69 from the start of transcription (+1), that is fully inducible by NaB treatment in LNCaP cells, but not in PC-3 cells. Unlike other well characterized NaB-regulated genes, Sp1 DNA sequences are not involved in NaB up-regulation of IGFBP-3 gene in LNCaP cells. Further deletion studies identified two independent regions critical for NaB-induced transactivation in LNCaP cells. These regions contain consensus binding sites for p53 and GATA, respectively, but mutational analyses and gel shift assays suggested that, while the p53 response element is required for NaB responsiveness, neither p53 nor GATA are involved. In summary, we have demonstrated that 1) NaB significantly up-regulates IGFBP-3 mRNA and protein levels in PC-3 and LNCaP prostate cancer cells; and 2) novel butyrate- responsive elements lacking consensus Sp1 sites are used in LNCaP cells.

In vitro effects of cholesteryl butyrate solid lipid nanospheres as a butyric acid pro-drug on melanoma cells: evaluation of antiproliferative activity and apoptosis induction

Literature data show that butyric acid derivatives bear a dose-dependent differentiative anti-proliferative activity on cancer cell lines and that apoptosis induction may play a major role. Although it was recently shown that solid lipid nanospheres (SLNs) are a suitable tool for several in vivo drug administration routes, there is little available information on melanoma cell lines. This study was aimed at evaluating the anti-proliferative and apoptotic in vitro effects of cholesteryl butyrate (chol-but) SLNs on melanoma cells. Increasing concentrations of chol-but SLNs were used to test two melanoma cell lines. Both cell lines were treated with Na-butyrate (Na-but) and chol-but SLNs for viability. Those tested with chol-but SLNs were more effective than Na-butirate (3 to 72 h). The apoptotic effects of chol-but SLNs were evaluated between 3 and 72 h by annexin-V (ANX-V)/propidium iodide (PI) staining and the antiproliferative effect by PI staining. Apoptosis anti-proliferative-regulatory proteins as bcl-2, Fas/APO1 (CD95) and PCNA (PC10) were also investigated. Flow cytometric analyses evidenced a G(0/1)-S transition block and a 'sub-G(0/1)' apoptotic peak from 0.5 to 1.0 mM butyric acid. In ANX-V/PI flow cytometric staining, a dose- and time-dependent increase in the apoptotic cell percentage (ANX-V+) coupled with a down-regulation of PC10 and bcl-2 and a parallel up-regulation of Fas/APO1 (CD95) were found in both lines started after 3 to 24 h of chol-but SLNs treatment. Results show that chol-but SLNs exerts a dose/time-dependent effect in melanoma cell apoptosis induction between 3 and 24 h and a dose but not time-dependent effect after 24 h of treatment.

Butyrate, a histone deacetylase inhibitor, activates the human IGF binding protein-3 promoter in breast cancer cells: molecular mechanism involves an Sp1/Sp3 multiprotein complex

Specific cell growth stimulators and inhibitors regulate IGF binding protein-3 (IGFBP-3), where in turn IGFBP-3 mediates their biological effects. The molecular mechanism(s) by which these factors regulate IGFBP-3 are unknown. Sodium butyrate, a histone deacetylase inhibitor causing growth arrest and differentiation, increases IGFBP-3 expression. We investigated the molecular mechanism of this induction using an IGFBP-3 promoter reporter system in MCF-7 and Hs578T breast cancer cells. IGFBP-3 promoter activity was induced up to 40-fold following a 24-h treatment with sodium butyrate and 46-fold in cells treated with trichostatin A, a pure histone deacetylase inhibitor. Deletion analysis of the IGFBP-3 promoter identified key sodium butyrate-responsive element(s) to a 45-bp region containing consensus binding sites for Sp1 and activating protein-2. Sp1 binding to the Sp1 site and Sp3 to the activating protein-2/GA-box played a functional role in sodium butyrate's activation of the IGFBP-3 promoter, however, with no change in binding direct sodium butyrate regulation was attributed to cofactors. The histone acetyltransferase p300 and histone deacetylase-1 were identified in multiprotein complexes containing DNA bound Sp1 and Sp3, with p300 accumulating following sodium butyrate treatment. Taken together, these data suggest that sodium butyrate increases IGFBP-3 expression by activating the IGFBP-3 promoter via an Sp1/Sp3 multiprotein complex, a mechanism that may be important for other key regulators of IGFBP-3.