Biotin supplementation increases expression of the cytochrome P450 1B1 gene in Jurkat cells, increasing the occurrence of single-stranded DNA breaks

CYP1B1 affects the integrity of the blood-brain barrier and oxidative stress in the striatum: An investigation of manganese-induced neurotoxicity

AIMS

Excessive influx of manganese (Mn) into the brain across the blood-brain barrier induces neurodegeneration. CYP1B1 is involved in the metabolism of arachidonic acid (AA) that affects vascular homeostasis. We aimed to investigate the effect of brain CYP1B1 on Mn-induced neurotoxicity.

METHOD

Brain Mn concentrations and α-synuclein accumulation were measured in wild-type and CYP1B1 knockout mice treated with MnCl2 (30 mg/kg) and biotin (0.2 g/kg) for 21 continuous days. Tight junctions and oxidative stress were analyzed in hCMEC/D3 and SH-SY5Y cells after the treatment with MnCl2 (200 μM) and CYP1B1-derived AA metabolites (HETEs and EETs).

RESULTS

Mn exposure inhibited brain CYP1B1, and CYP1B1 deficiency increased brain Mn concentrations and accelerated α-synuclein deposition in the striatum. CYP1B1 deficiency disrupted the integrity of the blood-brain barrier (BBB) and increased the ratio of 3, 4-dihydroxyphenylacetic acid (DOPAC) to dopamine in the striatum. HETEs attenuated Mn-induced inhibition of tight junctions by activating PPARγ in endothelial cells. Additionally, EETs attenuated Mn-induced up-regulation of the KLF/MAO-B axis and down-regulation of NRF2 in neuronal cells. Biotin up-regulated brain CYP1B1 and reduced Mn-induced neurotoxicity in mice.

CONCLUSIONS

Brain CYP1B1 plays a critical role in both cerebrovascular and dopamine homeostasis, which might serve as a novel therapeutic target for the prevention of Mn-induced neurotoxicity.

Human microbiome and prostate cancer development: current insights into the prevention and treatment

The huge communities of microorganisms that symbiotically colonize humans are recognized as significant players in health and disease. The human microbiome may influence prostate cancer development. To date, several studies have focused on the effect of prostate infections as well as the composition of the human microbiome in relation to prostate cancer risk. Current studies suggest that the microbiota of men with prostate cancer significantly differs from that of healthy men, demonstrating that certain bacteria could be associated with cancer development as well as altered responses to treatment. In healthy individuals, the microbiome plays a crucial role in the maintenance of homeostasis of body metabolism. Dysbiosis may contribute to the emergence of health problems, including malignancy through affecting systemic immune responses and creating systemic inflammation, and changing serum hormone levels. In this review, we discuss recent data about how the microbes colonizing different parts of the human body including urinary tract, gastrointestinal tract, oral cavity, and skin might affect the risk of developing prostate cancer. Furthermore, we discuss strategies to target the microbiome for risk assessment, prevention, and treatment of prostate cancer.

Nanoformulated Single-Stranded RNA-Based Adjuvant with a Coordinative Amphiphile as an Effective Stabilizer: Inducing Humoral Immune Response by Activation of Antigen-Presenting Cells

As agonists of TLR7/8, single-stranded RNAs (ssRNAs) are safe and promising adjuvants that do not cause off-target effects or innate immune overactivation. However, low stability prevents them from mounting sufficient immune responses. This study evaluates the adjuvant effects of ssRNA derived from the cricket paralysis virus intergenic region internal ribosome entry site, formulated as nanoparticles with a coordinative amphiphile, containing a zinc/dipicolylamine complex moiety as a coordinative phosphate binder, as a stabilizer for RNA-based adjuvants. The nanoformulated ssRNA adjuvant was resistant to enzymatic degradation in vitro and in vivo, and that with a coordinative amphiphile bearing an oleyl group (CA-O) was approximately 100 nm, promoted effective recognition, and improved activation of antigen-presenting cells, leading to better induction of neutralizing antibodies following single immunization. Hence, CA-O may increase the efficacy of ssRNA-based adjuvants, proving useful to meet the urgent need for vaccines during pathogen outbreaks.

Cytochrome P450 1B1: role in health and disease and effect of nutrition on its expression

This review summarizes the available literature stating CYP1B1 to provide the readers with a comprehensive understanding of its role in different diseases, as well as the importance of nutrition in their control in terms of the influence of different nutrients on its expression. CYP1B1, a member of the cytochrome P450 enzyme family is expressed in different human tissues and is known to contribute to different life alarming pathologies. Particularly, till now much attention has been paid to its involvement in the development of primary congenital glaucoma (PCG) and cancer. However, recently there are some reports highlighting CYP1B1 as a potential regulator in energy homeostasis and adipogenesis thus promoting obesity and hypertension as well. Therefore, seeking out effective strategies to modulate the expression of CYP1B1 is a challenging task. In this context, nutrients based strategies will be the best choice as they are mostly harmless and are easily available in one's diet. In conclusion, this article will be helpful in providing a base for further research that is needed to identify the role of CYP1B1 in progression of different diseases, hypertension and obesity in particular, and then to present the effectiveness, mechanisms, and biologic plausibility of nutrients against its expression.

Metabolic Biosynthesis Pathways Identified from Fecal Microbiome Associated with Prostate Cancer

BACKGROUND

The fecal microbiome is associated with prostate cancer risk factors (obesity, inflammation) and can metabolize and produce various products that may influence cancer but have yet to be defined in prostate cancer.

OBJECTIVE

To investigate gut bacterial diversity, identify specific metabolic pathways associated with disease, and develop a microbiome risk profile for prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

After prospective collection of 133 rectal swab samples 2 wk before the transrectal prostate biopsy, we perform 16S rRNA amplicon sequencing on 105 samples (64 with cancer, 41 without cancer). Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was applied to infer functional categories associated with taxonomic composition. The p values were adjusted using the false discovery rate. The α- and β-diversity analyses were performed using QIIME. The Mann-Whitney U test was employed to evaluate the statistical significance of β-diversity distances within and between groups of interest, and least absolute shrinkage and selection operator (LASSO) regression analysis was used to determine pathway significance.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The detection of prostate cancer on transrectal prostate needle biopsy and 16s microbiome profile.

RESULTS AND LIMITATIONS

We identified significant associations between total community composition and cancer/non-cancer status (Bray-Curtis distance metric, p<0.01). We identified significant differences in enrichments of Bacteroides and Streptococcus species in cancer (all p<0.04). Folate (LDA 3.8) and arginine (LDA 4.1) were the most significantly altered pathways. We formed a novel microbiome-derived risk factor for prostate cancer based on 10 aberrant metabolic pathways (area under curve=0.64, p=0.02).

CONCLUSIONS

Microbiome analyses on men undergoing prostate biopsy noted mostly similar bacterial species diversity among men diagnosed with and without prostate cancer. The microbiome may have subtle influences on prostate cancer but are likely patient-specific and would require paired analysis and precise manipulation, such as improvement of natural bacterial folate production.

PATIENT SUMMARY

Microbiome evaluation may provide patients with personalized data regarding the presence or absence of particular bacteria that have metabolic functions and implications regarding prostate cancer risk. The study provides a basis to investigate the manipulation of aberrant microbiomes to reduce prostate cancer risk.

Modulation of the rat hepatic cytochrome P4501A subfamily using biotin supplementation

Studies have found that biotin favors glucose and lipid metabolism, and medications containing biotin have been developed. Despite the use of biotin as a pharmacological agent, few studies have addressed toxicity aspects including the possible interaction with cytochrome P450 enzyme family. This study analyzed the effects of pharmacological doses of biotin on the expression and activity of the cytochrome P4501A subfamily involved in the metabolism of xenobiotics. Wistar rats were treated daily with biotin (2 mg/kg, i.p.), while the control groups were treated with saline. All of the rats were sacrificed by cervical dislocation after 1, 3, 5, or 7 days of treatment. CYP1A1 and CYP1A2 mRNAs were modified by biotin while enzyme activity and protein concentration were not affected. The lack of an effect of biotin on CYP1A activity was confirmed using other experimental strategies, including (i) cotreatment of the animals with biotin and a known CYP1A inducer; (ii) the addition of biotin to the reaction mixtures for the measurement of CYP1A1 and CYP1A2 activities; and (iii) the use of an S9 mixture that was prepared from control and biotin-treated rats to analyze the activation of benzo[a]pyrene (BaP) into mutagenic metabolites using the Ames test. The results suggest that biotin does not influence the CYP1A-mediated metabolism of xenobiotics.

The influence of micronutrients in cell culture: a reflection on viability and genomic stability

Micronutrients, including minerals and vitamins, are indispensable to DNA metabolic pathways and thus are as important for life as macronutrients. Without the proper nutrients, genomic instability compromises homeostasis, leading to chronic diseases and certain types of cancer. Cell-culture media try to mimic the in vivo environment, providing in vitro models used to infer cells' responses to different stimuli. This review summarizes and discusses studies of cell-culture supplementation with micronutrients that can increase cell viability and genomic stability, with a particular focus on previous in vitro experiments. In these studies, the cell-culture media include certain vitamins and minerals at concentrations not equal to the physiological levels. In many common culture media, the sole source of micronutrients is fetal bovine serum (FBS), which contributes to only 5-10% of the media composition. Minimal attention has been dedicated to FBS composition, micronutrients in cell cultures as a whole, or the influence of micronutrients on the viability and genetics of cultured cells. Further studies better evaluating micronutrients' roles at a molecular level and influence on the genomic stability of cells are still needed.

Biotin requirements for DNA damage prevention

Biotin serves as a covalently bound coenzyme in five human carboxylases; biotin is also attached to histones H2A, H3, and H4, although the abundance of biotinylated histones is low. Biotinylation of both carboxylases and histones is catalyzed by holocarboxylase synthetase. Human biotin requirements are unknown. Recommendations for adequate intake of biotin are based on the typical intake of biotin in an apparently healthy population, which is only a crude estimate of the true intake due to analytical problems. Importantly, intake recommendations do not take into account possible effects of biotin deficiency on impairing genome stability. Recent studies suggest that biotin deficiency causes de-repression of long terminal repeats, thereby causing genome instability. While it was originally proposed that these effects are caused by loss of biotinylated histones, more recent evidence suggests a more immediate role of holocarboxylase synthetase in forming multiprotein complexes in chromatin that are important for gene repression. Holocarboxylase synthetase appears to interact physically with the methyl-CpG-binding domain protein 2 and, perhaps, histone methyl transferases, thereby creating epigenetic synergies between biotinylation and methylation events. These observations might offer a mechanistic explanation for some of the birth defects seen in biotin-deficient animal models.

Biological Effects of Pharmacological Concentrations of Biotin

Understanding the molecular mechanisms of vitamins has opened new perspectives regarding the relationship between nutritional signals and biological functions, which, in turn, has led to the development of new therapeutic agents. Although little is known about water-soluble vitamins as genetic modulators, evidence about their effects on gene expression has grown. In the case of biotin, besides its role as a carboxylase prosthetic group, it also affects gene expression and has a wide repertoire of effects on biological functions. Only recently, the role of pharmacological concentrations of biotin on systemic functions has attracted attention, and it is now being reconsidered with the help of new technologies. This novel approach could lead to new perspectives in its use as a therapeutic agent. The present review is focused on the effects of pharmacological concentrations of biotin on several biological functions and on the biotin signaling pathways that participate in gene expression.

Biotin deficiency and biotin excess: effects on the female reproductive system

Biotin deficiency and biotin excess have both been found to affect reproduction and cause teratogenic effects. In the reproductive tract, however, the effects of biotin have not been well established yet. We investigated the effects of varying biotin content diets on the oestrus cycle, ovarian morphology, estradiol and progesterone serum levels, and the uterine mRNA abundance of their nuclear receptors, as well as on the activity of the estradiol-degrading group of enzymes cytochrome P450 (CYP) in the liver. Three-week-old female BALB/cAnN Hsd mice were fed a biotin-deficient, a biotin-control, or a biotin-supplemented diet (0, 7.2 or 400 micromol of free biotin/kg diet, respectively) over a period of nine weeks. Striking effects were observed in the biotin-deficient group: mice showed arrested estrous cycle on the day of diestrus and changes in ovary morphology. Estradiol serum concentration increased 49.2% in biotin-deficient mice compared to the control group, while the enzymatic activities of CYP1A2 and CYP2B2 increased (P<0.05). The mRNA abundance of nuclear estrogen and progesterone receptors decreased in the biotin-deficient mice. In the biotin-supplemented group we found that, in spite of a significant (P<0.05) decrease in the number of primary and Graafian follicles and in CYP1A2 activities, mice exhibited 105.4% higher serum estradiol concentration than the control group. No changes in the expression of the nuclear receptors were observed. No significant differences were observed in serum progesterone among the groups. Our results indicate that both the deficiency and the excess of biotin have significant effects on the female mouse reproductive system.

Cytochrome P450 1B1 Expression in Glial Cell Tumors: An Immunotherapeutic Target

PURPOSE

Among central nervous system malignancies, cytochrome P450 1B1 (CYP1B1) expression has only been characterized in medulloblastoma. An immunotherapeutic agent targeting this antigen was shown to safely stimulate a good immune response. To evaluate the viability of further research efforts targeting this antigen, we examined the expression of CYP1B1 in glial cell malignancies.

EXPERIMENTAL DESIGN

We studied the frequency and extent of CYP1B1 expression by immunohistochemical analysis in 269 glial tumors (including all major pathologic types) on a tissue microarray. Results were categorized by percentage of cells stained and intensity of cytoplasmic staining within cells. Correlation of CYP1B1 expression with patient prognosis was evaluated by univariate and multivariate analyses.

RESULTS

Overall, increased CYP1B1 expression in glial tumors was associated with decreased patient survival time (P < 0.0014 for both percentage and intensity of staining). A significant difference existed in percentage and intensity of staining between astrocytic and oligodendroglial tumors (P = 0.0002 and 0.0003, respectively), between grades of tumors (P < 0.0001 and 0.0079), and between pathologic types of tumors (P < 0.0001 and 0.0339). Positive CYP1B1 staining was seen in 81% of glioblastomas, 84% of anaplastic astrocytomas, 61% of oligodendrogliomas, and 67% of anaplastic oligodendrogliomas. Paradoxically, within specific tumor pathologies, there was a trend toward increased survival as CYP1B1 expression increased. However, in the multivariate analysis, this trend disappeared, and CYP1B1 expression seemed prognostically neutral.

CONCLUSION

CYP1B1 is frequently expressed in a variety of gliomas and could be used as a target for immunotherapy.

Biotin supplementation decreases the expression of the SERCA3 gene (ATP2A3) in Jurkat cells, thus, triggering unfolded protein response

Protein folding in the endoplasmic reticulum (ER) depends on Ca(2+); uptake of Ca(2+) into the ER is mediated by sarco/endoplasmic reticulum Ca(2+)-ATPase 3 (SERCA3). The 5'-flanking region of the SERCA3 gene (ATP2A3) contains numerous binding sites for the transcription factors Sp1 and Sp3. Biotin affects the nuclear abundance of Sp1 and Sp3, which may act as transcriptional activators or repressors. Here we determined whether biotin affects the expression of the SERCA3 gene and, thus, protein folding in human lymphoid cells. Jurkat cells were cultured in media containing 0.025 nmol/L biotin (denoted "deficient") or 10 nmol/L biotin ("supplemented"). The transcriptional activity of the full-length human SERCA3 promoter was 50% lower in biotin-supplemented cells compared to biotin-deficient cells. Biotin-dependent repressors bind to elements located 731-1312 bp upstream from the transcription start site in the SERCA3 gene. The following suggest that low expression of SERCA3 in biotin-supplemented cells impaired folding of secretory proteins in the ER, triggering unfolded protein response: (i) sequestration of Ca(2+) in the ER decreased by 14-24% in response to biotin supplementation; (ii) secretion of interleukin-2 into the extracellular space decreased by 75% in response to biotin supplementation; (iii) the nuclear abundance of stress-induced transcription factors increased in response to biotin supplementation; and (iv) the abundance of stress-related proteins such ubiquitin activating enzyme 1, growth arrest and DNA damage 153 gene, X-box binding protein 1 and phosphorylated eukaryotic translation initiation factor 2alpha increased in response to biotin supplementation. Collectively, this study suggests that supplements containing pharmacological doses of biotin may cause cell stress by impairing protein folding in the ER.

Uptake, localization, and noncarboxylase roles of biotin

Evidence is emerging that biotin participates in processes other than classical carboxylation reactions. Specifically, novel roles for biotin in cell signaling, gene expression, and chromatin structure have been identified in recent years. Human cells accumulate biotin by using both the sodium-dependent multivitamin transporter and monocarboxylate transporter 1. These transporters and other biotin-binding proteins partition biotin to compartments involved in biotin signaling: cytoplasm, mitochondria, and nuclei. The activity of cell signals such as biotinyl-AMP, Sp1 and Sp3, nuclear factor (NF)-kappaB, and receptor tyrosine kinases depends on biotin supply. Consistent with a role for biotin and its catabolites in modulating these cell signals, greater than 2000 biotin-dependent genes have been identified in various human tissues. Many biotin-dependent gene products play roles in signal transduction and localize to the cell nucleus, consistent with a role for biotin in cell signaling. Posttranscriptional events related to ribosomal activity and protein folding may further contribute to effects of biotin on gene expression. Finally, research has shown that biotinidase and holocarboxylase synthetase mediate covalent binding of biotin to histones (DNA-binding proteins), affecting chromatin structure; at least seven biotinylation sites have been identified in human histones. Biotinylation of histones appears to play a role in cell proliferation, gene silencing, and the cellular response to DNA repair. Roles for biotin in cell signaling and chromatin structure are consistent with the notion that biotin has a unique significance in cell biology.

Marginal maternal biotin deficiency in CD-1 mice reduces fetal mass of biotin-dependent carboxylases

Marginal maternal biotin deficiency reduces hepatic activity of biotin-dependent carboxylases and causes high rates of fetal birth defects in mice. We tested the hypothesis that the decreased carboxylase activity observed in deficient dams and their offspring is mediated by decreased abundance of biotinylated carboxylases, decreased expression of their mRNAs, or both. During gestation, CD-1 mice were fed a diet that induced biotin deficiency or a biotin-sufficient diet. On gestational d 17, gravid uteri were removed, and each live fetus was examined grossly for defects. The expected high incidence of cleft palate (83%) in offspring was observed. In maternal and fetal liver, acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase, and beta-methylcrotonyl-CoA carboxylase abundances were determined by Western blotting; the content of mRNAs for most of these enzymes and holocarboxylase synthetase was determined by real-time RT-PCR. Biotin deficiency significantly reduced the abundance of the carboxylases in maternal and fetal liver; neither the content of mRNAs for the carboxylases nor holocarboxylase synthetase changed. This study provides evidence that the decrease in carboxylase activities is attributable to a decrease in the abundance of biotinylated carboxylases; further, this effect is more severe in fetuses than dams.

High-throughput immunoblotting identifies biotin-dependent signaling proteins in HepG2 hepatocarcinoma cells

Biotin affects the abundance of mRNA coding for approximately 10% of genes expressed in human-derived hepatocarcinoma (HepG2) cells. Here, we determined whether effects of biotin on gene expression are associated with changes in the abundance of distinct proteins in cell signaling and structure. HepG2 cells were cultured in media containing the following concentrations of biotin: 0.025 nmol/L (denoted "deficient"), 0.25 nmol/L ("physiological" = control), and 10 nmol/L ("pharmacological") for 10 d before harvesting. The abundance of 1009 proteins from whole-cell extracts was quantified by using high-throughput immunoblots. The abundance of 44 proteins changed by at least 25% in biotin-deficient and biotin-supplemented cells compared with physiological controls. One third of these proteins participate in cell signaling. Specifically, proteins associated with receptor tyrosine kinase-mediated signaling were identified as targets of biotin; the abundance of these proteins was greater in biotin-deficient cells than in controls. This was associated with increased DNA-binding activities of the transcription factors Fos and Jun, and increased expression of a reporter gene driven by activator protein (AP)1-binding elements in biotin-deficient cells compared with physiological controls. The abundance of selected signaling proteins was not paralleled by the abundance of mRNA, suggesting that biotin affects expression of these genes at a post-transcriptional step. Additional clusters of biotin-responsive proteins were identified that play roles in cytoskeleton homeostasis, nuclear structure and transport, and neuroscience. This study is consistent with the existence of clusters of biotin-responsive proteins in distinct biological processes, including signaling by Fos/Jun; the latter might mediate the proinflammatory and antiapoptotic effects of biotin deficiency.

Riboflavin deficiency causes protein and DNA damage in HepG2 cells, triggering arrest in G1 phase of the cell cycle

Eukaryotes convert riboflavin to flavin adenine dinucleotide, which serves as a coenzyme for glutathione reductase and other enzymes. Glutathione reductase mediates the regeneration of reduced glutathione, which plays an important role in scavenging free radicals and reactive oxygen species. Here we tested the hypothesis that riboflavin deficiency decreases glutathione reductase activity in HepG2 liver cells, causing oxidative damage to proteins and DNA, and cell cycle arrest. As a secondary goal, we determined whether riboflavin deficiency is associated with gene expression patterns indicating cell stress. Cells were cultured in riboflavin-deficient and riboflavin-supplemented media for 4 days. Activity of glutathione reductase was not detectable in cells cultured in riboflavin-deficient medium. Riboflavin deficiency was associated with an increase in the abundance of damaged (carbonylated) proteins and with increased incidence of DNA strand breaks. Damage to proteins and DNA was paralleled by increased abundance of the stress-related transcription factor GADD153. Riboflavin-deficient cells arrested in G1 phase of the cell cycle. Moreover, oxidative stress caused by riboflavin deficiency was associated with increased expression of clusters of genes that play roles in cell stress and apoptosis. For example, the abundance of the pro-apoptotic pleiomorphic adenoma gene-like 1 gene was 183% greater in riboflavin-deficient cells compared with riboflavin-sufficient controls. We conclude that riboflavin deficiency is associated with oxidative damage to proteins and DNA in liver cells, leading to cell stress and G1 phase arrest.