GABA and hepatocellular carcinoma

Heat-killed Prevotella intermedia promotes the progression of oral squamous cell carcinoma by inhibiting the expression of tumor suppressors and affecting the tumor microenvironment

BACKGROUND

Oral microbial dysbiosis contributes to the development of oral squamous cell carcinoma (OSCC). Our previous study showed that Prevotella intermedia (P. intermedia) were enriched in the oral mucosal surface, plaque, and saliva of patients with OSCC. Intratumoral microbiome could reshape the immune system and influence the development of various tumors. However, the invasion status of human OSCC tissues by P. intermedia and the pathway through which intratumoral P. intermedia potentiates tumor progression remain unexplored.

METHODS

P. intermedia in human OSCC or normal tissues was detected by FISH. A mouse OSCC cell line SCC7 was adopted to investigate the effects of heat-killed P. intermedia treatment on cell proliferation, invasion, and cytokine release by using CCK-8 assay, transwell invasion assay and ELISA. Moreover, we established a mouse transplanted tumor model by using SCC7 cells, injected heat-killed P. intermedia into tumor tissues, and investigated the effects of heat-killed P. intermedia on tumor growth, invasion, cytokine levels, immune cell infiltrations, and expression levels by using gross observation, H&E staining, ELISA, immunohistochemistry, mRNA sequencing, and transcriptomic analysis.

RESULTS

Our results indicated that P. intermedia were abundant in OSCC and surrounding muscle tissues. Heat-killed P. intermedia promoted SCC7 cell proliferation, invasion and proinflammatory cytokine secretions, accelerated transplanted tumor growth in mice, exacerbate muscle and perineural invasion of OSCC, elevated the serum levels of IL-17A, IL-6, TNF-α, IFN-γ, and PD-L1, induced Treg cells M2 type macrophages in mouse transplanted tumors. The data of transcriptomic analysis revealed that heat-killed P. intermedia increased the expression levels of inflammatory cytokines and chemokines while reduced the expression levels of some tumor suppressor genes in mouse transplanted tumors. Additionally, IL-17 signaling pathway was upregulated whereas GABAergic system was downregulated by heat-killed P. intermedia treatment.

CONCLUSIONS

Taken together, our results suggest that P. intermedia could inhibit the expression of tumor suppressors, alter the tumor microenvironment, and promote the progression of OSCC.

GABA Administration Ameliorates the Toxicity of Doxorubicin on CSF and the Brain of Albino Rats

Background

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the mammalian brain and is a non-proteinogenic amino acid. Doxorubcin (DOX) or adriamycin is one of the most potent chemotherapy drugs for breast cancer.

Purpose

This study focused on diminishing the brain injury and neurotoxicity of doxorubicin (DOX) by GABA administration.

Methods

Rats were randomly divided into four groups (8 rats each), which were the control group, DOX group (3 mg/kg for 4 weeks, then 2 mg/kg for 2 weeks), GABA group (2 mg/kg for 21 days), and DOX + GABA group (treated as the second and third groups). Neurotoxicity and brain injury were assessed by determining CSF biomarkers, serum inflammatory markers, and histopathological evaluation of the cerebral cortex.

Results

DOX treatment significantly increased the levels of all CSF biomarkers (S100B, IL-1β, ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), glial fibrillary acidic protein (GFAP), spectrin breakdown products (SBDP145), and C-C motif chemokine ligand 2 (CCL2) and all inflammatory markers (IL-6, TNF-α, and IFN-γ), causing extensive neutrophilic infiltration and great alteration in the cerebral cortex architecture as evidence of neurotoxicity. The oral administration of GABA significantly reduced the levels of all CSF biomarkers and inflammatory markers and restored the normal architecture of the cerebral cortex, with observed ameliorations in neutrophilic infiltration.

Conclusion

GABA administration can ameliorate neurotoxicity and protect the brain against the negative effects of DOX treatment.

Effects of fungal based bioactive compounds on human health: Review paper

Since the first years of history, microbial fermentation products such as bread, wine, yogurt and vinegar have always been noteworthy regarding their nutritional and health effects. Similarly, mushrooms have been a valuable food product in point of both nutrition and medicine due to their rich chemical components. Alternatively, filamentous fungi, which can be easier to produce, play an active role in the synthesis of some bioactive compounds, which are also important for health, as well as being rich in protein content. Therefore, this review presents some important bioactive compounds (bioactive peptides, chitin/chitosan, β-glucan, gamma-aminobutyric acid, L-carnitine, ergosterol and fructooligosaccharides) synthesized by fungal strains and their health benefits. In addition, potential probiotic- and prebiotic fungi were researched to determine their effects on gut microbiota. The current uses of fungal based bioactive compounds for cancer treatment were also discussed. The use of fungal strains in the food industry, especially to develop innovative food production, has been seen as promising microorganisms in obtaining healthy and nutritious food.

Regulation of Gamma-Aminobutyric Acid Transaminase Expression and Its Clinical Significance in Hepatocellular Carcinoma

Background

Gamma-aminobutyric acid transaminase (ABAT) catalyzes the conversion of gamma-aminobutyric acid (GABA) into succinic semialdehyde. Although some evidence supports a key role of ABAT in the progression of hepatocellular carcinoma (HCC), no systematic analysis is available. Thus, this study aimed to investigate the possible mechanisms related to low ABAT expression and the prognostic value and potential functions of ABAT in HCC.

Methods

We obtained relevant datasets from the Encyclopedia of RNA Interactomes, MethSurv, cBioPortal, TISIDB and The Cancer Genome Atlas and used bioinformatic methods to analyze DNA methylation, copy number variation, gene mutation, and upstream microRNAs (miRNAs) of ABAT, exploring the potential relationship between ABAT expression and the prognosis, glycolysis, and immune infiltration in HCC.

Results

The results indicated that ABAT expression was lower in HCC tumor tissues than in normal tissues or adjacent tissues. Low ABAT expression was related to patient age, T stage classification, pathologic stage, histological grade, and alpha-fetoprotein level of HCC. Kaplan-Meier survival analyses indicated that low ABAT expression was correlated with poor HCC prognosis. ABAT was also verified as an independent risk factor in HCC via Cox multivariate analysis. Gene set enrichment analysis showed enrichment in various signaling pathways. Furthermore, DNA methylation, copy number variation, and gene mutation potentially induced low ABAT expression; miR-135a-5p was a potential upstream miRNA of ABAT. Additionally, ABAT expression was associated with glycolysis-related genes, infiltrated immune cells, immunoinhibitors, and immunostimulators in HCC.

Conclusions

Our study reveals that deficient ABAT expression is correlated with disease progression and poor prognosis in HCC because of its role in tumorigenesis and tumor immunity.

Production of Anserine-Rich Fish Sauce from Giant Masu Salmon, Oncorhynchus masou masou and γ-Aminobutyric Acid (GABA)-Enrichment by Lactobacillus plantarum Strain N10

Previously, we developed a novel production technique for giant masu salmon (GMS). This study aimed to develop a fish sauce from GMS to explore ways to efficiently utilize the salmon and to enrich the fish sauce with γ-aminobutyric acid (GABA) by microbial fermentation. The minced bodies of GMS were autolyzed by endogenous protease at 55 °C and 60 °C. During autolysis, the changes in total free amino acids and protein size was monitored by LC-MS and SDS-PAGE analysis, respectively. After 96 h, fish sauce was prepared by heating, and the amino acid composition was analyzed by LC-MS. To enrich the fish sauce with GABA, Lactobacillus plantarum strain N10 was added and incubated at 28 °C for 48 h. The total free amino acids content significantly increased for 96 h. SDS-PAGE analysis showed that major bands at 200 kDa and 48 kDa detected at 0 h gradually disappeared over time. The ratio of anserine to total amino acids in the fish sauce was approximately 36%. The concentration of GABA in the fish sauce significantly increased through the addition of strain N10. Thus, anserine-rich fish sauce could be quickly produced from GMS, and the fish sauce was enriched with GABA by microbial fermentation.

Induction of functional erythropoietin and erythropoietin receptor gene expression by gamma-aminobutyric acid and piperine in kidney epithelial cells

AIMS

The aim of this study was to evaluate gamma-aminobutyric acid (GABA)- and piperine-induced erythropoietin (EPO) and EPO-receptor expression.

MATERIALS AND METHODS

The effect of GABA and piperine on cell viability was examined using kidney epithelial cells. Expression levels of EPO and EPO-R mRNA and protein were evaluated in response to GABA and piperine treatments. GABA- and piperine-mediated activation of the mitogen-activated protein kinase (MAPK) signaling pathway was investigated. Additionally, EPO function was evaluated using conditioned media containing EPO. The GABA receptor type involved in this process was identified.

KEY FINDINGS

Messenger RNA and protein expression levels of EPO and EPO-R significantly increased in response to treatment with GABA, piperine, or the combination of both, compared with control. GABA plus piperine synergistically enhanced EPO and EPO-R expression through p38 and c-Jun N-terminal kinase (JNK) MAPK signaling pathways, but not through the extracellular signal-regulated kinase (ERK) MAPK pathway. SB203580 and SP600125 (p38 and JNK pathway inhibitors, respectively) attenuated GABA plus piperine-induced EPO and EPO-R expression. Treatment of macrophages with EPO-containing conditioned media induced mRNA expression of interleukin (IL)-10 and nuclear factor (NF)-κB due to the interaction between EPO and EPO-R. Interestingly, GABA-induced EPO and EPO-R expression was mediated through GABA_A, not GABA_B, receptor activation.

SIGNIFICANCE

These findings demonstrate that GABA plus piperine-mediated p38 and JNK MAPK activation increases EPO and EPO-R expression, resulting in up-regulation of IL-10 and NF-κB.

A label-retaining but unipotent cell population resides in biliary compartment of mammalian liver

Cells with slow proliferation kinetics that retain the nuclear label over long time periods-the label-retaining cells (LRCs)-represent multipotent stem cells in a number of adult tissues. Since the identity of liver LRCs (LLRCs) had remained elusive we utilized a genetic approach to reveal LLRCs in normal non-injured livers and characterized their regenerative properties in vivo and in culture. We found that LLRCs were located in biliary vessels and participated in the regeneration of biliary but not hepatocyte injury. In culture experiments the sorted LLRCs displayed an enhanced self-renewal capacity but a unipotent biliary differentiation potential. Transcriptome analysis revealed a unique set of tumorigenesis- and nervous system-related genes upregulated in LLRCs when compared to non-LRC cholangiocytes. We conclude that the LLRCs established during the normal morphogenesis of the liver do not represent a multipotent primitive somatic stem cell population but act as unipotent biliary progenitor cells.

A miRNAs panel promotes the proliferation and invasion of colorectal cancer cells by targeting GABBR1

MicroRNAs (miRNAs) have been implicated in the regulation of colorectal cancer. Despite the expression of miR-17-92 cluster in cancer has been gradually revealed, the role of each individual miRNAs in colorectal cancer still remains unclear. We studied the impact of miR-106a/b, miR-20a/b, and miR-17 of miR-17-92 cluster on colorectal cancer cells. Real-time quantitative polymerase chain reactions (RT-PCR) were used to test these five miRNAs expression in colorectal cancer cell line HCT116. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assays, Bromodeoxyuridine (BrdU), and Transwell invasion assays were used to explore the effects of these five miRNAs in colorectal cancer cells. Luciferase reporter assay, RT-PCR, and western blotting were performed to validate the interaction of these five miRNAs with the gamma-amino-butyric acid type B receptor 1(GABBR1). We found that these five miRNAs were significantly upregulated in colorectal cancer samples compared with normal tissues. Forced expression of these five miRNAs significantly promoted HCT116 and HT-29 cells proliferation and invasion. We further found that these five miRNAs function as oncogenes in colorectal cancer by specifically binding to the 3-untranslated regions (3'UTR) of GABBR1.Furthermore, inhibition of GABBR1 could mimic the function of miRNAs in HCT116 cells, while overexpression of GABBR1 blocked the function of miRNAs-promoted proliferation and invasion. In conclusion, miR-106a/b, miR-20a/b, and miR-17 contribute to the proliferation and invasion of colorectal cancer by targeting their common target gene, GABBR1, and played a critical role in the proliferation and invasion of colorectal cancer.

A study on quality components and sleep-promoting effects of GABA black tea

The aims of this study were to analyze the changes in quality components of gamma (γ)-aminobutyric acid (GABA) black tea during processing, and to investigate the effect of three dosages of GABA black tea on sleep improvement.

Metabolomic Analysis of Liver Tissue from the VX2 Rabbit Model of Secondary Liver Tumors

Purpose. The incidence of liver neoplasms is rising in USA. The purpose of this study was to determine metabolic profiles of liver tissue during early cancer development. Methods. We used the rabbit VX2 model of liver tumors (LT) and a control group consisting of sham animals implanted with Gelfoam into their livers (LG). After two weeks from implantation, liver tissue from lobes with and without tumor was obtained from experimental animals (LT+/LT−) as well as liver tissue from controls (LG+/LG−). Peaks obtained by Gas Chromatography-Mass Spectrometry were subjected to identification. 56 metabolites were identified and their profiles compared between groups using principal component analysis (PCA) and a mixed-effect two-way ANOVA model. Results. Animals recovered from surgery uneventfully. Analyses identified a metabolite profile that significantly differs in experimental conditions after controlling the False Discovery Rate (FDR). 16 metabolites concentrations differed significantly when comparing samples from (LT+/LT−) to samples from (LG+/LG−) livers. A significant difference was also shown in 20 metabolites when comparing samples from (LT+) liver lobes to samples from (LT−) liver lobes. Conclusion. Normal liver tissue harboring malignancy had a distinct metabolic signature. The role of metabolic profiles on liver biopsies for the detection of early liver cancer remains to be determined.

Integrating transcriptomics and metabonomics to unravel modes-of-action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in HepG2 cells

BACKGROUND

The integration of different 'omics' technologies has already been shown in several in vivo studies to offer a complementary insight into cellular responses to toxic challenges. Being interested in developing in vitro cellular models as alternative to animal-based toxicity assays, we hypothesize that combining transcriptomics and metabonomics data improves the understanding of molecular mechanisms underlying the effects caused by a toxic compound also in vitro in human cells. To test this hypothesis, and with the focus on non-genotoxic carcinogenesis as an endpoint of toxicity, in the present study, the human hepatocarcinoma cell line HepG2 was exposed to the well-known environmental carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

RESULTS

Transcriptomics as well as metabonomics analyses demonstrated changes in TCDD-exposed HepG2 in common metabolic processes, e.g. amino acid metabolism, of which some of the changes only being confirmed if both 'omics' were integrated. In particular, this integrated analysis identified unique pathway maps involved in receptor-mediated mechanisms, such as the G-protein coupled receptor protein (GPCR) signaling pathway maps, in which the significantly up-regulated gene son of sevenless 1 (SOS1) seems to play an important role. SOS1 is an activator of several members of the RAS superfamily, a group of small GTPases known for their role in carcinogenesis.

CONCLUSIONS

The results presented here were not only comparable with other in vitro studies but also with in vivo studies. Moreover, new insights on the molecular responses caused by TCDD exposure were gained by the cross-omics analysis.

Relieving occupational fatigue by consumption of a beverage containing γ-amino butyric acid

To elucidate the effect of γ-aminobutyric acid (GABA) on both psychological and physical fatigue and on the performance advances for task solving, we assigned an arithmetic task for the Uchida-Kraepelin Psychodiagnostic Test (UKT) to 30 healthy Japanese subjects, 9 of whom were diagnosed as having chronic fatigue. The subjects were administered 250 mL of a test beverage containing GABA at the dose of 0, 25, and 50 mg before assigning task for the UKT. Psychological fatigue assessed by the Visual Analogue Scale (VAS) was significantly lower in the group administrated the beverage containing 50 mg GABA than in the control group (p<0.05). The results of the Profile of Mood States (POMS) also indicated that psychological fatigue was significantly reduced in the 50-mg-GABA group. The salivary secretion levels of chromogranin A and cortisol-markers of physical fatigue-in both 25-mg and 50-mg-GABA groups were significantly lower than those in the control group. The 50-mg-GABA group also showed higher score on UKT by solving the arithmetic task more accurately than the control group (p<0.01). The results suggest that intake of GABA-containing beverages, especially those containing 50 mg of GABA, may help reduce both psychological and physical fatigue and improve task-solving ability.

Protective role of γ-aminobutyric acid against chronic renal failure in rats

The protective effect of γ-aminobutyric acid (GABA) against chronic renal failure (CRF) was investigated using a remnant kidney model with 5/6 nephrectomized rats. Nephrectomy led to renal dysfunction, which was evaluated via several parameters including serum urea nitrogen, creatinine (Cr) and Cr clearance. However, the administration of GABA ameliorated renal dysfunction, and a longer administration period of GABA increased its protective effect. In addition, nephrectomized control rats showed an elevation in the fractional excretion of sodium (FENa) with an increase in urinary sodium, while GABA led to a significant decline in FENa. Moreover, nephrectomy resulted in a decrease of serum albumin and an increase of urinary protein with a change in the urinary protein pattern, whereas the rats administered GABA showed improvement in these changes associated with CRF caused by nephrectomy. This suggests that GABA would inhibit the disease progression and have a protective role against CRF. As one of the risk factors for CRF progression, hypertension was also regulated by GABA. The results also indicate that GABA may play a protective role against CRF through improvement of the serum lipid profile, with reductions in triglyceride and total cholesterol. Furthermore, nephrectomy led to renal oxidative stress with a decrease in the activity of antioxidative enzymes and elevation of lipid peroxidation. The administration of GABA attenuated oxidative stress induced by nephrectomy through an increase in superoxide dismutase and catalase, and decrease in lipid peroxidation. The histopathological lesions, including glomerular, tubular and interstitial lesions, under nephrectomy were also improved by GABA with the inhibition of fibronectin expression. This study demonstrated that GABA attenuated renal dysfunction via regulation of blood pressure and lipid profile, and it also ameliorated the oxidative stress induced by nephrectomy, suggesting the promising potential of GABA in protecting against renal failure progression.

Baclofen, a GABAB receptor agonist, inhibits human hepatocellular carcinoma cell growth in vitro and in vivo

Gamma aminobutyric acid (GABA) has been reported to affect cancer development, but the activation of its type B receptor (GABABR) has shown contradictory effects on the progress of human carcinoma. In this study, we investigated the antitumor effect of the GABABR agonist baclofen (Bac) on growth of human hepatocellular carcinoma (HCC) in vitro and in vivo. We found Bac induced G(0)/G(1) phase arrest which was associated with down-regulation of intracellular cAMP level, and up-regulation of p21(WAF1) protein expression as well as its phosphorylation level. These in vitro effects could be abrogated by pretreatment with the specific GABABR antagonist phaclofen (Pha). Moreover, systemic administration of Bac significantly suppressed Bel-7402 xenograft tumor growth. Our data support the inhibitory effect of GABABR activation on HCC development, which would raise the possibility to develop Bac as a therapeutic drug for the treatment of HCC.

Regulatory effects of corticosterone on ornithine decarboxylase activity during liver regeneration in rats

AIMS

The regulation of ornithine decarboxylase (ODC) gene expression and enzyme activity by corticosterone during rat liver regeneration induced by partial hepatectomy (PH) was evaluated.

METHODS

Bilateral adrenalectomies were performed on ether-anesthetized rats 3 days before PH. Corticosterone in sesame oil was injected subcutaneously to adrenalectomized rats. ODC mRNA, ODC protein and enzyme activity were detected by in situ hybridization, Western blot and high performance liquid chromatography (HPLC), respectively.

RESULTS

The ODC mRNA levels, protein accumulation and enzyme activity were lower in the intact liver compared to the regenerating liver. After PH, mRNA levels were remarkably enhanced in all groups and peaked at 5 h post-PH, and presented a persistent increase only in adrenalectomy rats during the regeneration process. Corticosterone treatment resulted in a dose-dependent decrease in ODC mRNA content after 5 h post-PH. ODC protein accumulation in adrenalectomy rats was higher than that in sham-adrenalectomy rats, but it decreased in corticosterone-treated (10 mg/kg) rats until 24 h post-PH, with a strong decline seen in 40 mg/kg corticosterone-treated rats. ODC activity was rapidly promoted, and the highest levels were observed at 6 h after PH in all groups. After corticosterone treatment, the activities declined significantly at 6 h post-PH, with the lowest value found in the 40 mg/kg group.

CONCLUSIONS

Corticosterone treatment results in dose-dependent decreases in ODC mRNA and enzyme protein both in the intact liver and the regenerating liver. The change in ODC activity is partially related to alterations of ODC mRNA and protein accumulation.

Relaxation and immunity enhancement effects of gamma-aminobutyric acid (GABA) administration in humans

The effect of orally administrated gamma-aminobutyric acid (GABA) on relaxation and immunity during stress has been investigated in humans. Two studies were conducted. The first evaluated the effect of GABA intake by 13 subjects on their brain waves. Electroencephalograms (EEG) were obtained after 3 tests on each volunteer as follows: intake only water, GABA, or L-theanine. After 60 minutes of administration, GABA significantly increases alpha waves and decreases beta waves compared to water or L-theanine. These findings denote that GABA not only induces relaxation but also reduces anxiety. The second study was conducted to see the role of relaxant and anxiolytic effects of GABA intake on immunity in stressed volunteers. Eight acrophobic subjects were divided into 2 groups (placebo and GABA). All subjects were crossing a suspended bridge as a stressful stimulus. Immunoglobulin A (IgA) levels in their saliva were monitored during bridge crossing. Placebo group showed marked decrease of their IgA levels, while GABA group showed significantly higher levels. In conclusion, GABA could work effectively as a natural relaxant and its effects could be seen within 1 hour of its administration to induce relaxation and diminish anxiety. Moreover, GABA administration could enhance immunity under stress conditions.

Protective effect of γ-aminobutyric acid against glycerol-induced acute renal failure in rats

To investigate the effect of gamma-aminobutyric acid (GABA) on acute renal failure, we used a rat model of acute tubular necrosis induced by glycerol. After deprivation of water for 6h, the rats received an injection of 50% glycerol into the muscle of the rear limb at 10 ml/kg body weight. GABA was then administered orally to the rats (100 or 500 mg/kg body weight/day) once every 12h for 3 days. The rats with acute renal failure showed arrested body weight gain and an increase of kidney weight, whereas oral administration of GABA attenuated the physiological changes induced by acute renal failure. However, GABA administration had no significant effect on increased urine volume. Oral administration of GABA at a dose of 100 or 500 mg/kg body weight/day for 3 days significantly improved the markedly elevated levels of blood urea nitrogen and creatinine and the reduced creatinine clearance related to progression of renal failure. Moreover, the rats with acute renal failure exhibited high levels of fractional excretion of sodium (FE(Na)) due to alteration of tubule function following injection of glycerol. However, administration of GABA lowered the FE(Na) levels dose-dependently. Furthermore, urine osmolarity was markedly reduced in control rats with acute renal failure as compared with normal rats, whereas it was significantly increased by administration of GABA at a dose of 500 mg/kg body weight/day. These results indicate that GABA has potential as a therapeutic agent against the renal damage involved in acute renal failure.

A new role for GABA: inhibition of tumor cell migration

GABA, the main inhibitory neurotransmitter in the vertebrate brain, participates outside the CNS in diverse functions such as platelet aggregation and the acrosomal reaction in spermatozoa. A recent study now demonstrates that GABA inhibits the migration of colon carcinoma cells, paving the way to the development of specific pharmacological agents that delay or inhibit invasion and metastasis of various cancer types.