Distribution of alcohol dehydrogenase isoenzymes in the human liver acinus

Effect of ADHI on hepatic stellate cell activation and liver fibrosis in mice

The relationship between alcohol dehydrogenase (ADH) and liver fibrosis has been studied, but the mechanism of ADH involvement in liver fibrosis remains unclear. The aim of the present study was to explore the role of ADHI, the classical liver ADH, in hepatic stellate cell (HSC) activation and the effect of 4-methylpyrazole (4-MP), an ADH inhibitor, on liver fibrosis induced by carbon tetrachloride (CCl₄) in mice. The results showed that overexpression of ADHI significantly increases proliferation, migration, adhesion and invasion rates of HSC-T6 cells as compared with controls. When HSC-T6 cells were activated by ethanol, TGF-β1 or LPS, the expression of ADHI was elevated significantly (P < 0.05). Overexpression of ADHI significantly increased the levels of COL1A1 and α-SMA, markers of HSC activation. Moreover, the expression of COL1A1 and α-SMA was decreased significantly by transfection of ADHI siRNA (P < 0.01). In a liver fibrosis mouse model ADH activity increased significantly and was highest in the 3rd week. The activity of ADH in the liver was correlated with its activity in the serum (P < 0.05). 4-MP significantly decreased ADH activity and ameliorated liver injury, and ADH activity was positively correlated with the Ishak score of liver fibrosis. In conclusion, ADHI plays an important role in the activation of HSC, and inhibition of ADH ameliorates liver fibrosis in mice.

The alcohol dehydrogenase isoenzyme (ADH I) as a marker of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is an important pregnancy liver disorder. The alterations of different enzymes activity in the hepatocytes in the course of liver diseases are reflected in an increase in the activity of the corresponding enzymes in the blood. In present study we assayed the activity of alcohol dehydrogenase (ADH) and its isoenzyme in the serum of patients with ICP. Serum were collected from 100 pregnancies with ICP in the second or third trimester of pregnancy. Serum samples were also taken from 100 healthy pregnant women. The activity of ADH I was measured by spectrofluorometric method, ADH total was measured by photometric method. There was significant increase in the activity of ADH I (2.79 mU/l vs. 1.72 mU/l) and total ADH activity (1103 mU/l vs. 682 mU/l) in the sera of women with ICP compared to the healthy pregnant women. Importantly, the sensitivity and specificity of ADH I for diagnosis of ICP were 85% and 91%, respectively. Area under the Receiver Operating Curve for ADH I in ICP was 0.81. The activity of ADH I in the sera of women with ICP is statistically significantly increased, which may have a diagnostic significance for ICP patients.

The role of alcohol dehydrogenase 1C in regulating inflammatory responses in ulcerative colitis

Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease caused by an interaction of genetics, immune responses, and environmental factors. However, the precise pathogenesis of UC remains poorly understood. The aim of the present study was to explore the potential target genes implicated in UC and to elucidate its underlying pathogenic mechanism. Firstly, three UC-associated microarray datasets (GSE75214, GSE87466, and GSE92517) were obtained to screen the differentially expressed genes (DEGs). As a result, alcohol dehydrogenase 1C (ADH1C) was the most significantly downregulated DEG in UC. We confirmed that ADH1C was downregulated in colonic tissue taken from patients with UC and colitis mice. Moreover, ADH1C expression was also decreased in colonic cell lines (NCM460 and HT29) treated with mixed proinflammatory cytokines (TNF-α, IFN-γ, IL-1β). Interestingly, we found that overexpression of ADH1C could distinctly decrease the production of IL-6 and IL-8. To elucidate the molecular mechanism of ADH1C in UC, gene set enrichment analysis (GSEA) was performed and demonstrated that immune-related pathways were mainly enriched in the low ADH1C group. Further studies displayed that STAT1/NF-κB pathway was activated in colitis mice and inflammatory cell model. Importantly, overexpression of ADH1C could suppress the phosphorylation of STAT1 and IκB. Therefore, ADH1C might regulate inflammatory responses through STAT1/NF-κB pathway. In conclusion, ADH1C was downregulated during inflammation, and its increased expression could inhibit the activation of STAT1/NF-κB pathway, thereby alleviating the secretion of IL-6 and IL-8. These findings indicate that ADH1C may be a potential therapeutic target for UC therapy.

Higher Activity of Alcohol Dehydrogenase Is Correlated with Hepatic Fibrogenesis

Hepatofibrosis can progress to cirrhosis and hepatocellular carcinoma (HCC). Prevention, stabilization, and reversal of disease progression are vital for patients with hepatofibrosis, and identifying the risk factors for hepatofibrosis is urgently needed. In this study, we examined the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in the fibrotic livers of HCC patients (n = 88) and comparied these results with activities in patients with normal livers (n = 74). A fibrosis-carcinoma rat model was used to study the activity of ADH in fibrosis and HCC and the relationship between innate ADH activity and the extent of hepatofibrosis or HCC. Substantial interindividual variations were found in the activities of ADH and ALDH in normal livers. The activity levels of total ADH, ADHI, and ADHII in fibrotic livers were significantly higher than those in normal livers (P < 0.001), whereas the activity of ALDH was slightly greater. The positive rates of ADHI and ADHII were 84.1% and 77.3%, respectively; the areas under the receiver operator characteristics (ROC) curve were 0.943 and 0.912, respectively. For the rat model compared with controls, ADH activity in liver was significantly increased at the fibrotic and HCC stages, and no significant difference was noted between ADH activity in the liver at these two stages. The innate activity of ADH in serum was well correlated with the extent of hepatofibrosis as indicated by Masson area%, Ki67⁺%, proliferating cell nuclear antigen ⁺%, and GST-p average density at fibrotic stage but not at HCC stage. A higher level of activity of ADH is a risk factor for hepatofibrogenesis and might be a prevention target for hepatofibrosis.

Activity of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in sera of patients with hepatitis C

INTRODUCTION

The changes of enzyme activity in the hepatocytes in the course of different liver diseases are reflected by increase of the corresponding enzyme activity in the plasma. For example, the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) correlate with the severity of the condition during cirrhosis. In this study we measured the activity of ADH isoenzymes and ALDH in the sera of patients with hepatitis C.

MATERIAL AND METHODS

Serum samples were taken from 60 patients suffering from viral hepatitis C and from 66 control subjects. Total ADH activity and class III and IV isoenzymes were measured by the photometric method and ALDH activity, ADH I and II by the fluorometric method.

RESULTS

The ADH activity was significantly higher in patients with hepatitis C than in healthy (p < 0.001). The total activity of ADH was 1284 mU/l in patients, and 745 mU/l (controls). The activity of isoenzymes classes ADH I and ADH II in the hepatitis C group increased respectively 55% (4.24 vs. 1.88 mU/l; p < 0.001) and 47% (26.63 vs. 14.11 mU/l; p < 0.001) in the comparison to the control. There was significant increase in the activity of ADH I isoenzyme (4.96 vs. 3.81 mU/l; p < 0.001) and ADH total (1833 vs. 1105 mU/l; p < 0.001) in patients with high viral load in comparison to patients with low viral load.

CONCLUSIONS

The activity of class I and II ADH isoenzymes in the sera of patients with hepatitis C is increased, and it seems to be caused by the release of these isoenzymes from damaged liver cells.

Alcohol metabolism and oesophageal cancer: a systematic review of the evidence

Alcohol is a major risk factor for oesophageal squamous cell carcinoma (OSCC), the most prevalent histological subtype of oesophageal cancer (OC) worldwide. The metabolism of alcohol is regulated by specific enzymes whose activity and expression is influenced by genetic polymorphisms. We conducted a systematic review of current epidemiological evidence of the relationship between alcohol intake and OC risk, including the role of tobacco smoking and functional polymorphisms of alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs). Potential biological mechanisms underlying oesophageal carcinogenesis are also discussed. Frequency and intensity of alcohol intake have been consistently associated with an increased risk of OSCC in regions with low and high incidence of the disease. The highest risk was reported among tobacco smokers, whereas the association between alcohol and OSCC risk was weak in the absence of tobacco use. The ADH1B, ADH1C and ALDH2 gene polymorphisms influence the risk of OSCC through modulation of acetaldehyde metabolism and propensity to alcohol intake. These functional variants may be suitable proxies of alcohol exposure for use in Mendelian randomization studies if complemented by reported alcohol intake data. Recent epidemiological and experimental studies investigating the role of alcohol consumption in OC development have implicated the microbiome as a new promising avenue for research, which entail novel potential mechanisms of alcohol-related oesophageal carcinogenesis. Microbial communities associated with alcohol consumption might be used as biomarkers to raise the potential of intervening among susceptible individuals.

Alcohol and Hepatocellular Carcinoma: Adding Fuel to the Flame

Primary tumors of the liver represent the fifth most common type of cancer in the world and the third leading cause of cancer-related death. Case-control studies from different countries report that chronic ethanol consumption is associated with an approximately 2-fold increased odds ratio for hepatocellular carcinoma (HCC). Despite the substantial epidemiologic data in humans demonstrating that chronic alcohol consumption is a major risk factor for HCC development, the pathways causing alcohol-induced liver cancer are poorly understood. In this overview, we summarize the epidemiological evidence for the association between alcohol and liver cancer, review the genetic, oncogenic, and epigenetic factors that drive HCC development synergistically with ethanol intake and discuss the essential molecular and metabolic pathways involved in alcohol-induced liver tumorigenesis.

Alcohol dehydrogenase and aldehyde dehydrogenase in malignant neoplasms

According to International Agency for Research on Cancer, ethanol and acetaldehyde belong to group 1 of human carcinogens. The accurate mechanism by which alcohol consumption enhances carcinogenesis is still unexplained. Alcohol is oxidized primarily by alcohol dehydrogenase (ADH) to acetaldehyde, a substance capable of initiating carcinogenesis by forming adducts with proteins and DNA and causing mutations. Next, acetaldehyde is metabolized by aldehyde dehydrogenase (ALDH) to acetate. In tissues of many cancers, we can observe significantly higher activity of total alcohol dehydrogenase with any change in aldehyde dehydrogenase activity in comparison with healthy cells. Moreover, in malignant diseases of digestive system, significantly increased activity of ADH isoenzymes class I, III and IV was found. The gynecological, brain and renal cancers exhibit increased activity of class I ADH. ADH and ALDH can play also a crucial regulatory role in initiation and progression of malignant diseases by participation in retinoic acid synthesis and elimination of toxic acetaldehyde. Besides, changes of enzymes activities in tumor cells are reflected in serum of cancer patients, which create the possibilities of application ADH isoenzymes as cancer markers.

Non-(13)CO2 targeted breath tests: a feasibility study

Breath tests allow a non-invasive and fast diagnostic of different specific enzymes' phenotypic functionality. Over the last decade several 13C-breath tests were successfully tested, with the (13)C-urea breath test being approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). The use of other targets than labeled (13)CO2 in exhaled breath offers additional possibilities. High sensitivity analytical technologies, such as proton-transfer reaction time-of-flight mass spectrometry, enable the detection of different volatile targets in the low ppb (parts per billion) range in real-time.In the current study volunteers received 0.8 mg deuterated 2-propanol, which was converted to d3-acetone (m/z 62.08) by alcohol dehydrogenase. D3-acetone (m/z 62.08) appeared in exhaled breath concentrations up to 30 ppb (at maximum). Parallel consumption of ethanol seems to reduce the activity of the enzyme, resulting in approximately 15-30% reduction of the produced d3-acetone. Phenotypic determination of enzyme activities is important, since the functionality of enzymes is influenced by factors such as age, sex, life-style, diet, organ function, metabolism, etc, which cannot be entirely accounted for by genetic factors.

The activity of class I, II, III and IV of alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in the wall of abdominal aortic aneurysms

OBJECTIVE

Human blood vessels contain a huge amount of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which play a significant role in the metabolism of many biological substances and participate in various metabolic pathways. The aim of this study was the investigation of the differences between the activities of ADH and ALDH in the wall of aortic aneurysm and wall of healthy aorta, that can explain the pathological background of aneurysm development.

METHODS

For the measurement of the activity of class I and II ADH isoenzymes and ALDH activity the fluorometric methods was employed. The total ADH activity and activity of class III and IV isoenzymes was measured by the photometric method. The study material consisted of vessels wall samples obtained from 45 abdominal aortic aneurysm.

RESULTS

The activity of the class I ADH isoenzyme was significantly lower in the wall of aortic aneurysm than in healthy aorta. The other tested classes of ADH showed the tendency to lower level of the activity in aneurysm tissue than that in wall of unchanged aorta. The activities of total ADH and ALDH were also not significantly lower in the aneurysms.

CONCLUSION

The decrease of the activity of class I ADH isoenzymes in the wall of aortic aneurysm may be a factor of some disorders in metabolic pathways with participation of these isoenzymes.

Alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase activity in the sera of patients with esophageal cancer

Various alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) exist in the human esophageal mucosa. In our last experiments we have shown that ADH and ALDH are present also in the esophageal cancer cells. Moreover, the activities of total ADH and class IV isoenzymes were significantly higher in cancer tissue than in healthy mucosa, which suggests that these changes may be reflected by enzyme activity in the serum. Therefore, we measured the activity of total alcohol dehydrogenase, and classes I-IV of this enzyme and aldehyde dehydrogenase in the sera of patients with this cancer. Serum samples were taken for routine biochemical investigation from 67 patients with esophageal cancer before treatment. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorometric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes, we employed the fluorometric methods, with class-specific fluorogenic substrates. The activity of class III alcohol dehydrogenase was measured by the photometric method with formaldehyde and class IV with m-nitrobenzaldehyde as a substrate. A statistically significant increase of class IV alcohol dehydrogenase isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased by about 26.5% (7.42 mU/l) in comparison to the control level (5.46 mU/l). The total alcohol dehydrogenase activity was significantly higher (30%) among patients with cancer. The activities of other tested ADH isoenzymes and total ALDH were unchanged. The activity of the class I ADH isoenzyme was significantly higher in the sera of drinkers with esophageal cancer than non-drinking patients. The increased total activity of alcohol dehydrogenase and class IV isoenzyme in the sera of patients with esophageal cancer probably can be caused by release of this isoenzyme from cancer cells or might be stimulated by alcohol drinking.

The activity of class I, II, III, and IV alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) in liver cancer

BACKGROUND

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are most abundant in the liver, are the main enzymes involved in ethanol and acetaldehyde metabolism.

AIMS

The purpose of this study was to compare the activity of ADH isoenzymes and ALDH between liver carcinoma cells and healthy hepatocytes.

PATIENTS

Samples were taken from 44 liver cancer patients (19 drinkers, 25 nondrinkers). Seventeen patients had primary liver tumors and 27 had metastatic liver tumors.

METHODS

Fluorimetric methods were used for measurement of the activity of class I and II ADH isoenzymes and ALDH activity. Total ADH activity and activity of class III and IV isoenzymes were measured by a photometric method.

RESULTS

The activities of total ADH, ALDH, and class I ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH showed a tendency toward higher activity in cancer than in normal cells. The differences between enzymes of drinkers and nondrinkers in both cancer and healthy tissue, were not significant.

CONCLUSION

Differences in the activities of total ADH, ALDH and class I ADH isoenzyme between cancer liver tissues and healthy hepatocytes might be a factor in ethanol metabolism disorders, which can intensify carcinogenesis.

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) activity in the sera of patients with liver cancer

The principal enzymes catalyzing the conversion of ethanol to acetate are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). The activities of these enzymes are elevated in the serum during the course of alcoholism or cirrhosis. In previous investigations we have found elevated levels of ADH, ALDH, and class I ADH activity in liver cancer cells. It can suggest that these changes may be reflected by enzyme activity in the serum. In this work, the activity of ADH isoenzymes, and ALDH in the sera of patients with liver cancer was measured. Serum samples were taken from 64 patients (28 drinkers, 36 nondrinkers), with liver cancer. 25 patients had primary and 39 metastatic liver tumors. Total ADH activity was measured by photometric method with p-nitrosodimethylaniline (NDMA) as a substrate and ALDH activity by the fluorimetric method with 6-methoxy-2-naphtaldehyde as a substrate. For the measurement of the activity of class I and II isoenzymes we employed the fluorimetric methods, with class-specific fluorogenic substrates. The activity of class III ADH was measured by the photometric method with formaldehyde and class IV with m-nitrobenzaldehyde as a substrate. A statistically significant increase of class I ADH isoenzymes was found in the sera of cancer patients. The median activity of this class isoenzyme in the total cancer group increased about 51% (2.94 mU/L) in the comparison to the control level (1.43 mU/L). The activity of the class I ADH isoenzyme was significantly higher in the sera of patients with metastatic tumors than with primary cancers. The activity of this class in the sera of drinkers and group of moderate drinkers was significantly higher in comparison to the control group and higher in the sera of heavy drinkers when compared with moderate drinking patients. The total ADH activity was significantly higher (44%) among patients with cancer than healthy ones. The activity of class I ADH isoenzymes was elevated only in the serum of patients with metastatic liver cancer. This increase of activity seems to be caused by the enzyme released from liver cancer cells and primary tumors originating in other organs.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in the cancer diseases

Epidemiological data have identified chronic alcohol consumption as a significant risk factor for cancer in humans. The exact mechanism of ethanol-associated carcinogenesis has remained unknown. The metabolism of ethanol leads to generation of acetaldehyde (AA), which is highly toxic and carcinogenic. The amount of acetaldehyde to which cells or tissues are exposed after alcohol ingestion may be of great importance and may, among others, affects carcinogenesis. Ethanol is metabolized to acetaldehyde by alcohol dehydrogenase (ADH). The enzyme responsible for oxidation of acetaldehyde is aldehyde dehydrogenase (ALDH). Both formation and degradation of acetaldehyde depends on the activity of these enzymes. The total alcohol dehydrogenase activity is significantly higher in cancer tissues than in this healthy organs (e.g. liver, stomach, esophagus, colorectum). Moreover the activity of ADH is much higher than the activity of ALDH. This suggests that cancer cells have a greater capability for ethanol oxidation but less ability to remove acetaldehyde than normal tissues. In addition significant differences of ADH isoenzymes activities between cancer tissues and healthy organs may be a factor intensifying carcinogenesis by the increased ability to acetaldehyde formation from ethanol and disorders in metabolism of some biologically important substances (e.g. retinoic acid). The changes in activity of particular ADH isoenzymes in the sera of patients with different cancers, seem to be caused by release of these isoenzymes from cancer cells, and may be useful for diagnostics of this cancer. The particular isoenzymes of ADH present in the serum may indicate the cancer localization.

A multiple reaction monitoring method for absolute quantification of the human liver alcohol dehydrogenase ADH1C1 isoenzyme

Although significant progress has been made in protein quantification using mass spectrometry during recent years, absolute protein quantification in complex biological systems remains a challenging task in proteomics. The use of stable isotope-labeled standard peptide is the most commonly used strategy for absolute quantification, but it might not be suitable in all instances. Here we report an alternative strategy that employs a stable isotope-labeled intact protein as an internal standard to absolutely quantify the alcohol dehydrogenase (ADH) expression level in a human liver sample. In combination with a new targeted proteomics approach employing the method of multiple reaction monitoring (MRM), we precisely and quantitatively measured the absolute protein expression level of an ADH isoenzyme, ADH1C1, in human liver. Isotope-labeled protein standards are predicted to be particularly useful for measurement of highly homologous isoenzymes such as ADHs where multiple signature peptides can be examined by MRM in a single experiment.

High and complementary expression patterns of alcohol and aldehyde dehydrogenases in the gastrointestinal tract: implications for Parkinson's disease

Parkinson's disease (PD) is a heterogeneous movement disorder characterized by progressive degeneration of dopamine neurons in substantia nigra. We have previously presented genetic evidence for the possible involvement of alcohol and aldehyde dehydrogenases (ADH; ALDH) by identifying genetic variants in ADH1C and ADH4 that associate with PD. The absence of the corresponding mRNA species in the brain led us to the hypothesis that one cause of PD could be defects in the defense systems against toxic aldehydes in the gastrointestinal tract. We investigated cellular expression of Adh1, Adh3, Adh4 and Aldh1 mRNA along the rodent GI tract. Using oligonucleotide in situ hybridization probes, we were able to resolve the specific distribution patterns of closely related members of the ADH family. In both mice and rats, Adh4 is transcribed in the epithelium of tongue, esophagus and stomach, whereas Adh1 was active from stomach to rectum in mice, and in duodenum, colon and rectum in rats. Adh1 and Adh4 mRNAs were present in the mouse gastric mucosa in nonoverlapping patterns, with Adh1 in the gastric glands and Adh4 in the gastric pits. Aldh1 was found in epithelial cells from tongue to jejunum in rats and from esophagus to colon in mice. Adh3 hybridization revealed low mRNA levels in all tissues investigated. The distribution and known physiological functions of the investigated ADHs and Aldh1 are compatible with a role in a defense system, protecting against alcohols, aldehydes and formaldehydes as well as being involved in retinoid metabolism.

Gender-related differences in hepatic activity of alcohol dehydrogenase isoenzymes and aldehyde dehydrogenase in humans

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are most abundant in the liver, are the main enzymes involved in ethanol metabolism in humans. Gender-related differences in total liver ADH and ALDH activity among different animal species have been observed in many studies. We measured total ADH and ALDH activity, and the activity of class I-IV ADH in the livers of male and female patients. Total ADH and class I and II ADH activities were significantly higher in males than in females (P=0.0052, P=0.0074, P=0.020, respectively). Class III and IV ADH and total ALDH activities were not significantly different between the genders (P=0.2917, P=0.0590, P=0.2940, respectively). The results of our study clearly show that there is a difference in enzymatic activity between male and female patients for those isoenzymes that actively participate in ethanol oxidation in the liver (class I and II ADH), although the main form of ADH in this organ is class III ADH.

Changes in the activity of alcohol dehydrogenase isoenzymes during the estrus cycle in the vagina of the rat

In rodents, the vaginal epithelium undergoes cyclical changes with an alternating pattern of keratinization and mucification. It has been known for decades that vitamin A and its active form retinoic acid are responsible for normal epithelial homeostasis. However, it has not so far been certain which enzymes catalyze the first and rate-limiting step in retinoic acid synthesis. By means of microdissection and ultrathin-layer gel electrophoresis, alcohol dehydrogenase isoenzyme activity was determined quantitatively in the various layers of the vaginal mucous membrane. It was found that, in the rat, only alcohol dehydrogenase 3 and 4 are expressed. Marked cyclical changes of alcohol dehydrogenase 4 activity in the stratum germinativum of the vaginal epithelium strongly support the assumption that this isoenzyme is responsible for retinoic acid synthesis, and that it is essential for the changes accompanying keratinization and mucification.